Search results for: biodegradable characteristics
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 7758

Search results for: biodegradable characteristics

468 Preliminary Studies on Poloxamer-Based Hydrogels with Oregano Essential Oil as Potential Topical Treatment of Cutaneous Papillomas

Authors: Ana Maria Muț, Georgeta Coneac, Ioana Olariu, Ștefana Avram, Ioana Zinuca Pavel, Ionela Daliana Minda, Lavinia Vlaia, Cristina Adriana Dehelean, Corina Danciu

Abstract:

Oregano essential oil is obtained from different parts of the plant Origanum vulgare (fam. Lamiaceae) and carvacrol and thymol are primary components, widely recognized for their antimicrobial activity, as well as their antiviral and antifungal properties. Poloxamers are triblock copolymers (Pluronic®), formed of three non-ionic blocks with a hydrophobic polyoxypropylene central chain flanked by two polyoxyethylene hydrophilic chains. They are known for their biocompatibility, sensitivity to temperature changes (sol-to-gel transition of aqueous solution with temperature increase), but also for their amphiphilic and surface active nature determining the formation of micelles, useful for solubilization of different hydrophobic compounds such as the terpenes and terpenoids contained in essential oils. Thus, these polymers, listed in European and US Pharmacopoeia and approved by FDA, are widely used as solubilizers and gelling agents for various pharmaceutical preparations, including topical hydrogels. The aim of this study was to investigate the posibility of solubilizing oregano essential oil (OEO) in polymeric micelles using polyoxypropylene (PPO)-polyoxyethylene (PEO)-polyoxypropylene (PPO) triblock polymers to obtain semisolid systems suitable for topical application. A formulation screening was performed, using Pluronic® F-127 in concentration of 20%, Pluronic® L-31, Pluronic® L-61 and Pluronic® L-62 in concentration of 0.5%, 0.8% respectively 1% to obtain the polymeric micelles-based systems. Then, to each selected system, with or without 10% absolute ethanol, 5% or 8% OEO was added. The obtained transparent poloxamer-based hydrogels containing solubilized OEO were further evaluated for pH, rheological characteristics (flow behaviour, viscosity, consistency and spreadability), using consacrated techniques like potentiometric titration, stationary shear flow test, penetrometric method and parallel plate method. Also, in vitro release and permeation of carvacrol from the hydrogels was carried out, using vertical diffusion cells and synthetic hydrophilic membrane and porcine skin respectively. The pH values and rheological features of all tested formulations were in accordance with official requirements for semisolid cutaneous preparations. But, the formulation containing 0.8% Pluronic® L-31, 10% absolute ethanol, 8% OEO and water and the formulation with 1% Pluronic® L-31, 5% OEO and water, produced the highest cumulative amounts of carvacrol released/permeated through the membrane. The present study demonstrated that oregano essential oil can be successfully solubilized in the investigated poloxamer-based hydrogels. These systems can be further investigated as potential topical therapy for cutaneous papillomas. Funding: This research was funded by Project PN-III-P1-1.1-TE2019-0130, Contract number TE47, Romania.

Keywords: oregano essential oil, carvacrol, poloxamer, topical hydrogels

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467 Transient Heat Transfer: Experimental Investigation near the Critical Point

Authors: Andreas Kohlhepp, Gerrit Schatte, Wieland Christoph, Spliethoff Hartmut

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In recent years the research of heat transfer phenomena of water and other working fluids near the critical point experiences a growing interest for power engineering applications. To match the highly volatile characteristics of renewable energies, conventional power plants need to shift towards flexible operation. This requires speeding up the load change dynamics of steam generators and their heating surfaces near the critical point. In dynamic load transients, both a high heat flux with an unfavorable ratio to the mass flux and a high difference in fluid and wall temperatures, may cause problems. It may lead to deteriorated heat transfer (at supercritical pressures), dry-out or departure from nucleate boiling (at subcritical pressures), all cases leading to an extensive rise of temperatures. For relevant technical applications, the heat transfer coefficients need to be predicted correctly in case of transient scenarios to prevent damage to the heated surfaces (membrane walls, tube bundles or fuel rods). In transient processes, the state of the art method of calculating the heat transfer coefficients is using a multitude of different steady-state correlations for the momentarily existing local parameters for each time step. This approach does not necessarily reflect the different cases that may lead to a significant variation of the heat transfer coefficients and shows gaps in the individual ranges of validity. An algorithm was implemented to calculate the transient behavior of steam generators during load changes. It is used to assess existing correlations for transient heat transfer calculations. It is also desirable to validate the calculation using experimental data. By the use of a new full-scale supercritical thermo-hydraulic test rig, experimental data is obtained to describe the transient phenomena under dynamic boundary conditions as mentioned above and to serve for validation of transient steam generator calculations. Aiming to improve correlations for the prediction of the onset of deteriorated heat transfer in both, stationary and transient cases the test rig was specially designed for this task. It is a closed loop design with a directly electrically heated evaporation tube, the total heating power of the evaporator tube and the preheater is 1MW. To allow a big range of parameters, including supercritical pressures, the maximum pressure rating is 380 bar. The measurements contain the most important extrinsic thermo-hydraulic parameters. Moreover, a high geometric resolution allows to accurately predict the local heat transfer coefficients and fluid enthalpies.

Keywords: departure from nucleate boiling, deteriorated heat transfer, dryout, supercritical working fluid, transient operation of steam generators

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466 Effects of Novel Protease Enzyme From Bacillus subtilis on Low Protein and Low Energy Guar Meal (Cyamopsis tetragonoloba) Meal Based Diets on Performance and Nutrients Digestibility in Broilers

Authors: Aqeel Ahmed Shad, Tanveer Ahmad, Muhammad Farooq Iqbal, Muhammad Javaid Asad

Abstract:

The supplemental effects of novel protease produced from Bacillus subtilis K-5 and beta-mannanase were evaluated on growth performance, carcass characteristics, nutrients digestibility, blood profile and intestinal morphometry of broilers fed guar meal (Cyamopsis tetragonoloba) based diets with reduced Crude Protein (CP), Essential Amino Acids (EAAs), and Metabolizable energy (ME) contents. One-day old Ross 308 broiler chicks (n=360) were randomly allotted to thirty six experimental units in a way that each of the nine dietary treatments received four replicates with ten birds per replicate. A control diet without guar meal (0GM) was formulated with standard nutrient specifications of Ross 308 for the starter and finisher phases. Two negative control diets, one with 5% (5GM) and second with 10% (10GM) guar meal, were formulated with reduction of 5% CP, 5% EAAs and 80 Kcal/kg ME. These three basal diets (no enzyme) were supplemented with novel protease enzyme (PROT) and commercial beta-mannanase (Beta-M) enzyme. The birds were reared up to 35d of age. The data on weekly body weight gain (BWG) and feed intake were recorded to compute feed:gain for the starter (0-21d) and finisher (22-35d) phases. At the end of 35d of experimental period, four birds per experimental unit were randomly selected for blood samples collection and later slaughtered for ileal digesta, intestinal tract and carcass trait sampling. The data on overall performance (1-35d) indicated improved (P<0.05) BWG and feed:gain in birds supplemented with PROT (1.41% and 1.67) and Beta-M (2.79% and 1.64) than non-supplemented groups. Improved (P<0.05) carcass yield, breast meat yield and thigh meat yield were noted with the supplementation of Beta-M. However, non-significant (P>0.05) effect on carcass traits was noted in broiler fed guar meal based PROT supplemented diets. Crude protein digestibility, nitrogen retention (Nret) and apparent digestibility coefficient for nitrogen (ADCN) were improved (P<0.05) only with PROT. The improvement in apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen (AMEn) was noted (P<0.05) with both supplemented enzymes. However, no effect (P>0.05) of enzyme addition was noted on blood glucose, total protein and cholesterol. Improved villus height of duodenum, jejunum and ileum was noted (P<0.05) with the addition of both enzymes. The EAAs digestibility was improved (P<0.05) only with PROT. In conclusion, beta-mannanase and protease supplementation better improved the overall bird performance in low nutrient profile guar meal based diets than non-supplemented diets.

Keywords: novel protease, guar meal, broilers, low protein diets, low metabolizable energy diets, nutrients digestibility

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465 Multisensory Science, Technology, Engineering and Mathematics Learning: Combined Hands-on and Virtual Science for Distance Learners of Food Chemistry

Authors: Paulomi Polly Burey, Mark Lynch

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It has been shown that laboratory activities can help cement understanding of theoretical concepts, but it is difficult to deliver such an activity to an online cohort and issues such as occupational health and safety in the students’ learning environment need to be considered. Chemistry, in particular, is one of the sciences where practical experience is beneficial for learning, however typical university experiments may not be suitable for the learning environment of a distance learner. Food provides an ideal medium for demonstrating chemical concepts, and along with a few simple physical and virtual tools provided by educators, analytical chemistry can be experienced by distance learners. Food chemistry experiments were designed to be carried out in a home-based environment that 1) Had sufficient scientific rigour and skill-building to reinforce theoretical concepts; 2) Were safe for use at home by university students and 3) Had the potential to enhance student learning by linking simple hands-on laboratory activities with high-level virtual science. Two main components of the resources were developed, a home laboratory experiment component, and a virtual laboratory component. For the home laboratory component, students were provided with laboratory kits, as well as a list of supplementary inexpensive chemical items that they could purchase from hardware stores and supermarkets. The experiments used were typical proximate analyses of food, as well as experiments focused on techniques such as spectrophotometry and chromatography. Written instructions for each experiment coupled with video laboratory demonstrations were used to train students on appropriate laboratory technique. Data that students collected in their home laboratory environment was collated across the class through shared documents, so that the group could carry out statistical analysis and experience a full laboratory experience from their own home. For the virtual laboratory component, students were able to view a laboratory safety induction and advised on good characteristics of a home laboratory space prior to carrying out their experiments. Following on from this activity, students observed laboratory demonstrations of the experimental series they would carry out in their learning environment. Finally, students were embedded in a virtual laboratory environment to experience complex chemical analyses with equipment that would be too costly and sensitive to be housed in their learning environment. To investigate the impact of the intervention, students were surveyed before and after the laboratory series to evaluate engagement and satisfaction with the course. Students were also assessed on their understanding of theoretical chemical concepts before and after the laboratory series to determine the impact on their learning. At the end of the intervention, focus groups were run to determine which aspects helped and hindered learning. It was found that the physical experiments helped students to understand laboratory technique, as well as methodology interpretation, particularly if they had not been in such a laboratory environment before. The virtual learning environment aided learning as it could be utilized for longer than a typical physical laboratory class, thus allowing further time on understanding techniques.

Keywords: chemistry, food science, future pedagogy, STEM education

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464 Promoting Incubation Support to Youth Led Enterprises: A Case Study from Bangladesh to Eradicate Hazardous Child Labour through Microfinance

Authors: Md Maruf Hossain Koli

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The issue of child labor is enormous and cannot be ignored in Bangladesh. The problem of child exploitation is a socio-economic reality of Bangladesh. This paper will indicate the causes, consequences, and possibilities of using microfinance as remedies of hazardous child labor in Bangladesh. Poverty is one of the main reasons for children to become child laborers. It is an indication of economic vulnerability, inadequate law, and enforcement system and cultural and social inequities along with the inaccessible and low-quality educational system. An attempt will be made in this paper to explore and analyze child labor scenario in Bangladesh and will explain holistic intervention of BRAC, the largest nongovernmental organization in the world to address child labor through promoting incubation support to youth-led enterprises. A combination of research methods were used to write this paper. These include non-reactive observation in the form of literature review, desk studies as well as reactive observation like site visits and, semi-structured interviews. Hazardous Child labor is a multi-dimensional and complex issue. This paper was guided by the answer following research questions to better understand the current context of hazardous child labor in Bangladesh, especially in Dhaka city. The author attempted to figure out why child labor should be considered as a development issue? Further, it also encountered why child labor in Bangladesh is not being reduced at an expected pace? And finally what could be a sustainable solution to eradicate this situation. One of the most challenging characteristics of child labor is that it interrupts a child’s education and cognitive development hence limiting the building of human capital and fostering intergenerational reproduction of poverty and social exclusion. Children who are working full-time and do not attend school, cannot develop the necessary skills. This leads them and their future generation to remain in poor socio-economic condition as they do not get a better paying job. The vicious cycle of poverty will be reproduced and will slow down sustainable development. The outcome of the research suggests that most of the parents send their children to work to help them to increase family income. In addition, most of the youth engaged in hazardous work want to get training, mentoring and easy access to finance to start their own business. The intervention of BRAC that includes classroom and on the job training, tailored mentoring, health support, access to microfinance and insurance help them to establish startup. This intervention is working in developing business and management capacity through public-private partnerships and technical consulting. Supporting entrepreneurs, improving working conditions with micro, small and medium enterprises and strengthening value chains focusing on youth and children engaged with hazardous child labor.

Keywords: child labour, enterprise development, microfinance, youth entrepreneurship

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463 Experimental Field for the Study of Soil-Atmosphere Interaction in Soft Soils

Authors: Andres Mejia-Ortiz, Catalina Lozada, German R. Santos, Rafael Angulo-Jaramillo, Bernardo Caicedo

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The interaction between atmospheric variables and soil properties is a determining factor when evaluating the flow of water through the soil. This interaction situation directly determines the behavior of the soil and greatly influences the changes that occur in it. The atmospheric variations such as changes in the relative humidity, air temperature, wind velocity and precipitation, are the external variables that reflect a greater incidence in the changes that are generated in the subsoil, as a consequence of the water flow in descending and ascending conditions. These environmental variations have a major importance in the study of the soil because the conditions of humidity and temperature in the soil surface depend on them. In addition, these variations control the thickness of the unsaturated zone and the position of the water table with respect to the surface. However, understanding the relationship between the atmosphere and the soil is a somewhat complex aspect. This is mainly due to the difficulty involved in estimating the changes that occur in the soil from climate changes; since this is a coupled process where act processes of mass transfer and heat. In this research, an experimental field was implemented to study in-situ the interaction between the atmosphere and the soft soils of the city of Bogota, Colombia. The soil under study consists of a 60 cm layer composed of two silts of similar characteristics at the surface and a deep soft clay deposit located under the silky material. It should be noted that the vegetal layer and organic matter were removed to avoid the evapotranspiration phenomenon. Instrumentation was carried on in situ through a field disposal of many measuring devices such as soil moisture sensors, thermocouples, relative humidity sensors, wind velocity sensor, among others; which allow registering the variations of both the atmospheric variables and the properties of the soil. With the information collected through field monitoring, the water balances were made using the Hydrus-1D software to determine the flow conditions that developed in the soil during the study. Also, the moisture profile for different periods and time intervals was determined by the balance supplied by Hydrus 1D; this profile was validated by experimental measurements. As a boundary condition, the actual evaporation rate was included using the semi-empirical equations proposed by different authors. In this study, it was obtained for the rainy periods a descending flow that was governed by the infiltration capacity of the soil. On the other hand, during dry periods. An increase in the actual evaporation of the soil induces an upward flow of water, increasing suction due to the decrease in moisture content. Also, cracks were developed accelerating the evaporation process. This work concerns to the study of soil-atmosphere interaction through the experimental field and it is a very useful tool since it allows considering all the factors and parameters of the soil in its natural state and real values of the different environmental conditions.

Keywords: field monitoring, soil-atmosphere, soft soils, soil-water balance

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462 Pricing Effects on Equitable Distribution of Forest Products and Livelihood Improvement in Nepalese Community Forestry

Authors: Laxuman Thakuri

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Despite the large number of in-depth case studies focused on policy analysis, institutional arrangement, and collective action of common property resource management; how the local institutions take the pricing decision of forest products in community forest management and what kinds of effects produce it, the answers of these questions are largely silent among the policy-makers and researchers alike. The study examined how the local institutions take the pricing decision of forest products in the lowland community forestry of Nepal and how the decisions affect to equitable distribution of benefits and livelihood improvement which are also objectives of Nepalese community forestry. The study assumes that forest products pricing decisions have multiple effects on equitable distribution and livelihood improvement in the areas having heterogeneous socio-economic conditions. The dissertation was carried out at four community forests of lowland, Nepal that has characteristics of high value species, matured-experience of community forest management and better record-keeping system of forest products production, pricing and distribution. The questionnaire survey, individual to group discussions and direct field observation were applied for data collection from the field, and Lorenz curve, gini-coefficient, χ²-text, and SWOT (Strong, Weak, Opportunity, and Threat) analysis were performed for data analysis and results interpretation. The dissertation demonstrates that the low pricing strategy of high-value forest products was supposed crucial to increase the access of socio-economically weak households, and to and control over the important forest products such as timber, but found counter productive as the strategy increased the access of socio-economically better-off households at higher rate. In addition, the strategy contradicts to collect a large-scale community fund and carry out livelihood improvement activities as per the community forestry objectives. The crucial part of the study is despite the fact of low pricing strategy; the timber alone contributed large part of community fund collection. The results revealed close relation between pricing decisions and livelihood objectives. The action research result shows that positive price discrimination can slightly reduce the prevailing inequality and increase the fund. However, it lacks to harness the full price of forest products and collects a large-scale community fund. For broader outcomes of common property resource management in terms of resource sustainability, equity, and livelihood opportunity, the study suggests local institutions to harness the full price of resource products with respect to the local market.

Keywords: community, equitable, forest, livelihood, socioeconomic, Nepal

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461 An Audit of Climate Change and Sustainability Teaching in Medical School

Authors: Karolina Wieczorek, Zofia Przypaśniak

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Climate change is a rapidly growing threat to global health, and part of the responsibility to combat it lies within the healthcare sector itself, including adequate education of future medical professionals. To mitigate the consequences, the General Medical Council (GMC) has equipped medical schools with a list of outcomes regarding sustainability teaching. Students are expected to analyze the impact of the healthcare sector’s emissions on climate change. The delivery of the related teaching content is, however, often inadequate and insufficient time is devoted for exploration of the topics. Teaching curricula lack in-depth exploration of the learning objectives. This study aims to assess the extent and characteristics of climate change and sustainability subjects teaching in the curriculum of a chosen UK medical school (Barts and The London School of Medicine and Dentistry). It compares the data to the national average scores from the Climate Change and Sustainability Teaching (C.A.S.T.) in Medical Education Audit to draw conclusions about teaching on a regional level. This is a single-center audit of the timetabled sessions of teaching in the medical course. The study looked at the academic year 2020/2021 which included a review of all non-elective, core curriculum teaching materials including tutorials, lectures, written resources, and assignments in all five years of the undergraduate and graduate degrees, focusing only on mandatory teaching attended by all students (excluding elective modules). The topics covered were crosschecked with GMC Outcomes for graduates: “Educating for Sustainable Healthcare – Priority Learning Outcomes” as gold standard to look for coverage of the outcomes and gaps in teaching. Quantitative data was collected in form of time allocated for teaching as proxy of time spent per individual outcomes. The data was collected independently by two students (KW and ZP) who have received prior training and assessed two separate data sets to increase interrater reliability. In terms of coverage of learning outcomes, 12 out of 13 were taught (with the national average being 9.7). The school ranked sixth in the UK for time spent per topic and second in terms of overall coverage, meaning the school has a broad range of topics taught with some being explored in more detail than others. For the first outcome 4 out of 4 objectives covered (average 3.5) with 47 minutes spent per outcome (average 84 min), for the second objective 5 out of 5 covered (average 3.5) with 46 minutes spent (average 20), for the third 3 out of 4 (average 2.5) with 10 mins pent (average 19 min). A disproportionately large amount of time is spent delivering teaching regarding air pollution (respiratory illnesses), which resulted in the topic of sustainability in other specialties being excluded from teaching (musculoskeletal, ophthalmology, pediatrics, renal). Conclusions: Currently, there is no coherent strategy on national teaching of climate change topics and as a result an unstandardized amount of time spent on teaching and coverage of objectives can be observed.

Keywords: audit, climate change, sustainability, education

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460 Smart Cities, Morphology of the Uncertain: A Study on Development Processes Applied by Amazonian Cities in Ecuador

Authors: Leonardo Coloma

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The world changes constantly, every second its properties vary due either natural factors or human intervention. As the most intelligent creatures on the planet, human beings have transformed the environment and paradoxically –have allowed ‘mother nature’ to lose species, accelerate the processes of climate change, the deterioration of the ozone layer, among others. The rapid population growth, the procurement, administration and distribution of resources, waste management, and technological advances are some of the factors that boost urban sprawl whose gray stain extends over the territory, facing challenges such as pollution, overpopulation and scarcity of resources. In Ecuador, these problems are added to the social, cultural, economic and political anomalies that have historically affected it. This fact can represent a greater delay when trying to solve global problems, without having paid attention to local inconveniences –smaller ones, but ones that could be the key to project smart solutions on bigger ones. This research aims to highlight the main characteristics of the development models adopted by two Amazonian cities, and analyze the impact of such urban growth on society; to finally define the parameters that would allow the development of an intelligent city in Ecuador, prepared for the challenges of the XXI Century. Contrasts in the climate, temperature, and landscape of Ecuadorian cities are fused with the cultural diversity of its people, generating a multiplicity of nuances of an indecipherable wealth. However, we strive to apply development models that do not recognize that wealth, not understanding them and ignoring that their proposals will vary according to where they are applied. Urban plans seem to take a bit of each of the new theories and proposals of development, which, in the encounter with the informal growth of cities, with those excluded and ‘isolated’ societies, generate absurd morphologies - where the uncertain becomes tangible. The desire to project smart cities is ever growing, but it is important to consider that this concept does not only have to do with the use of information and communication technologies. Its success is achieved when advances in science and technology allow the establishment of a better relationship between people and their context (natural and built). As a research methodology, urban analysis through mappings, diagrams and geographical studies, as well as the identification of sensorial elements when living the city, will make evident the shortcomings of the urban models adopted by certain populations of the Ecuadorian Amazon. Following the vision of previous investigations started since 2014 as part of ‘Centro de Acciones Urbanas,’ the results of this study will encourage the dialogue between the city (as a physical fact) and those who ‘make the city’ (people as its main actors). This research will allow the development of workshops and meetings with different professionals, organizations and individuals in general.

Keywords: Latin American cities, smart cities, urban development, urban morphology, urban sprawl

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459 Linguistic Cyberbullying, a Legislative Approach

Authors: Simona Maria Ignat

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Bullying online has been an increasing studied topic during the last years. Different approaches, psychological, linguistic, or computational, have been applied. To our best knowledge, a definition and a set of characteristics of phenomenon agreed internationally as a common framework are still waiting for answers. Thus, the objectives of this paper are the identification of bullying utterances on Twitter and their algorithms. This research paper is focused on the identification of words or groups of words, categorized as “utterances”, with bullying effect, from Twitter platform, extracted on a set of legislative criteria. This set is the result of analysis followed by synthesis of law documents on bullying(online) from United States of America, European Union, and Ireland. The outcome is a linguistic corpus with approximatively 10,000 entries. The methods applied to the first objective have been the following. The discourse analysis has been applied in identification of keywords with bullying effect in texts from Google search engine, Images link. Transcription and anonymization have been applied on texts grouped in CL1 (Corpus linguistics 1). The keywords search method and the legislative criteria have been used for identifying bullying utterances from Twitter. The texts with at least 30 representations on Twitter have been grouped. They form the second corpus linguistics, Bullying utterances from Twitter (CL2). The entries have been identified by using the legislative criteria on the the BoW method principle. The BoW is a method of extracting words or group of words with same meaning in any context. The methods applied for reaching the second objective is the conversion of parts of speech to alphabetical and numerical symbols and writing the bullying utterances as algorithms. The converted form of parts of speech has been chosen on the criterion of relevance within bullying message. The inductive reasoning approach has been applied in sampling and identifying the algorithms. The results are groups with interchangeable elements. The outcomes convey two aspects of bullying: the form and the content or meaning. The form conveys the intentional intimidation against somebody, expressed at the level of texts by grammatical and lexical marks. This outcome has applicability in the forensic linguistics for establishing the intentionality of an action. Another outcome of form is a complex of graphemic variations essential in detecting harmful texts online. This research enriches the lexicon already known on the topic. The second aspect, the content, revealed the topics like threat, harassment, assault, or suicide. They are subcategories of a broader harmful content which is a constant concern for task forces and legislators at national and international levels. These topic – outcomes of the dataset are a valuable source of detection. The analysis of content revealed algorithms and lexicons which could be applied to other harmful contents. A third outcome of content are the conveyances of Stylistics, which is a rich source of discourse analysis of social media platforms. In conclusion, this corpus linguistics is structured on legislative criteria and could be used in various fields.

Keywords: corpus linguistics, cyberbullying, legislation, natural language processing, twitter

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458 Innovation and Entrepreneurship in the South of China

Authors: Federica Marangio

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This study looks at the triangle of knowledge: research-education-innovation as growth engine of an inclusive and sustainable society, where the research is the strategic process which allows the acquisition of knowledge, innovation appraises the knowledge acquired and the education is the enabling factor of the human capital to create entrepreneurial capital. Where does Italy and China stand in the global geography of innovation? Europe is calling on a smart, inclusive and sustainable growth through a specializing process that looks at the social and economic challenges, able to understand the characteristics of specific geographic areas. It is easily questionable why it is not as simple as it looks to come up with entrepreneurial ideas in all the geographic areas. Seen that the technology plus the human capital should be the means through which is possible to innovate and contribute to the boost of innovation culture, then the young educated people can be seen as the society changing agents and it becomes clear the importance of investigating the skills and competencies that lead to innovation. By starting innovation-based activities, other countries on an international level, are able now to be part of an healthy innovative ecosystem which is the result of a strong growth policy which enables innovation. Analyzing the geography of the innovation on a global scale, comes to light that the innovative entrepreneurship is the process which portrays the competitiveness of the regions in the knowledge-based economy as strategic process able to match intellectual capital and market opportunities. The level of innovative entrepreneurship is not only the result of the endogenous growth ability of the enterprises, but also by significant relations with other enterprises, universities, other centers of education and institutions. To obtain more innovative entrepreneurship is necessary to stimulate more synergy between all these territory actors in order to create, access and value existing and new knowledge ready to be disseminate. This study focuses on individual’s lived experience and the researcher believed that she can’t understand the human actions without understanding the meaning that they attribute to their thoughts, feelings, beliefs and so given she needed to understand the deeper perspectives captured through face-to face interaction. A case study approach will contribute to the betterment of knowledge in this field. This case study will represent a picture of the innovative ecosystem and the entrepreneurial mindset as a key ingredient of endogenous growth and a must for sustainable local and regional development and social cohesion. The case study will be realized analyzing two Chinese companies. A structured set of questions will be asked in order to gain details on what generated success or failure in the different situations with the past and at the moment of the research. Everything will be recorded not to lose important information during the transcription phase. While this work is not geared toward testing a priori hypotheses, it is nevertheless useful to examine whether the projects undertaken by the companies, were stimulated by enabling factors that, as result, enhanced or hampered the local innovation culture.

Keywords: Entrepreneurship, education, geography of innovation, education.

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457 Changes of Chemical Composition and Physicochemical Properties of Banana during Ethylene-Induced Ripening

Authors: Chiun-C.R. Wang, Po-Wen Yen, Chien-Chun Huang

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Banana is produced in large quantities in tropical and subtropical areas. Banana is one of the important fruits which constitute a valuable source of energy, vitamins and minerals. The ripening and maturity standards of banana vary from country to country depending on the expected shelf life of market. The compositions of bananas change dramatically during ethylene-induced ripening that are categorized as nutritive values and commercial utilization. Nevertheless, there is few study reporting the changes of physicochemical properties of banana starch during ethylene-induced ripening of green banana. The objectives of this study were to investigate the changes of chemical composition and enzyme activity of banana and physicochemical properties of banana starch during ethylene-induced ripening. Green bananas were harvested and ripened by ethylene gas at low temperature (15℃) for seven stages. At each stage, banana was sliced and freeze-dried for banana flour preparation. The changes of total starch, resistant starch, chemical compositions, physicochemical properties, activity of amylase, polyphenolic oxidase (PPO) and phenylalanine ammonia lyase (PAL) of banana were analyzed each stage during ripening. The banana starch was isolated and analyzed for gelatinization properties, pasting properties and microscopic appearance each stage of ripening. The results indicated that the highest total starch and resistant starch content of green banana were 76.2% and 34.6%, respectively at the harvest stage. Both total starch and resistant starch content were significantly declined to 25.3% and 8.8%, respectively at the seventh stage. Soluble sugars content of banana increased from 1.21% at harvest stage to 37.72% at seventh stage during ethylene-induced ripening. Swelling power of banana flour decreased with the progress of ripening stage, but solubility increased. These results strongly related with the decreases of starch content of banana flour during ethylene-induced ripening. Both water insoluble and alcohol insoluble solids of banana flour decreased with the progress of ripening stage. Both activity of PPO and PAL increased, but the total free phenolics content decreased, with the increases of ripening stages. As ripening stage extended, the gelatinization enthalpy of banana starch significantly decreased from 15.31 J/g at the harvest stage to 10.55 J/g at the seventh stage. The peak viscosity and setback increased with the progress of ripening stages in the pasting properties of banana starch. The highest final viscosity, 5701 RVU, of banana starch slurry was found at the seventh stage. The scanning electron micrograph of banana starch showed the shapes of banana starch appeared to be round and elongated forms, ranging in 10-50 μm at the harvest stage. As the banana closed to ripe status, some parallel striations were observed on the surface of banana starch granular which could be caused by enzyme reaction during ripening. These results inferred that the highest resistant starch was found in the green banana at the harvest stage could be considered as a potential application of healthy foods. The changes of chemical composition and physicochemical properties of banana could be caused by the hydrolysis of enzymes during the ethylene-induced ripening treatment.

Keywords: ethylene-induced ripening, banana starch, resistant starch, soluble sugars, physicochemical properties, gelatinization enthalpy, pasting characteristics, microscopic appearance

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456 Production of Nanocomposite Electrical Contact Materials Ag-SnO2, W-Cu and Cu-C in Thermal Plasma

Authors: A. V. Samokhin, A. A. Fadeev, M. A. Sinaiskii, N. V. Alekseev, A. V. Kolesnikov

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Composite materials where metal matrix is reinforced by ceramic or metal particles are of great interest for use in the manufacturing of electrical contacts. Significant improvement of the composite physical and mechanical properties as well as increase of the performance parameters of composite-based products can be achieved if the nanoscale structure in the composite materials is obtained by using nanosized powders as starting components. The results of nanosized composite powders synthesis (Ag-SnO2, W-Cu and Cu-C) in the DC thermal plasma flows are presented in this paper. The investigations included the following processes: - Recondensation of micron powder mixture Ag + SnO2 in a nitrogen plasma; - The reduction of the oxide powders mixture (WO3 + CuO) in a hydrogen-nitrogen plasma; - Decomposition of the copper formate and copper acetate powders in nitrogen plasma. The calculations of equilibrium compositions of multicomponent systems Ag-Sn-O-N, W-Cu-O-H-N and Cu-O-C-H-N in the temperature range of 400-5000 K were carried to estimate basic process characteristics. Experimental studies of the processes were performed using a plasma reactor with a confined jet flow. The plasma jet net power was in the range of 2 - 13 kW, and the feedstock flow rate was up to 0.35 kg/h. The obtained powders were characterized by TEM, HR-TEM, SEM, EDS, ED-XRF, XRD, BET and QEA methods. Nanocomposite Ag-SnO2 (12 wt. %). Processing of the initial powder mixture (Ag-SnO2) in nitrogen thermal plasma stream allowed to produce nanopowders with a specific surface area up to 24 m2/g, consisting predominantly of particles with size less than 100 nm. According to XRD results, tin was present in the obtained products as SnO2 phase, and also as intermetallic phases AgxSn. Nanocomposite W-Cu (20 wt .%). Reduction of (WO3+CuO) mixture in the hydrogen-nitrogen plasma provides W-Cu nanopowder with particle sizes in the range of 10-150 nm. The particles have mainly spherical shape and structure tungsten core - copper shell. The thickness of the shell is about several nanometers, the shell is composed of copper and its oxides (Cu2O, CuO). The nanopowders had 1.5 wt. % oxygen impurity. Heat treatment in a hydrogen atmosphere allows to reduce the oxygen content to less than 0.1 wt. %. Nanocomposite Cu-C. Copper nanopowders were found as products of the starting copper compounds decomposition. The nanopowders primarily had a spherical shape with a particle size of less than 100 nm. The main phase was copper, with small amount of Cu2O and CuO oxides. Copper formate decomposition products had a specific surface area 2.5-7 m2/g and contained 0.15 - 4 wt. % carbon; and copper acetate decomposition products had the specific surface area 5-35 m2/g, and carbon content of 0.3 - 5 wt. %. Compacting of nanocomposites (sintering in hydrogen for Ag-SnO2 and electric spark sintering (SPS) for W-Cu) showed that the samples having a relative density of 97-98 % can be obtained with a submicron structure. The studies indicate the possibility of using high-intensity plasma processes to create new technologies to produce nanocomposite materials for electric contacts.

Keywords: electrical contact, material, nanocomposite, plasma, synthesis

Procedia PDF Downloads 235
455 Unlocking New Room of Production in Brown Field; ‎Integration of Geological Data Conditioned 3D Reservoir ‎Modelling of Lower Senonian Matulla Formation, RAS ‎Budran Field, East Central Gulf of Suez, Egypt

Authors: Nader Mohamed

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The Late Cretaceous deposits are well developed through-out Egypt. This is due to a ‎transgression phase associated with the subsidence caused by the neo-Tethyan rift event that ‎took place across the northern margin of Africa, resulting in a period of dominantly marine ‎deposits in the Gulf of Suez. The Late Cretaceous Nezzazat Group represents the Cenomanian, ‎Turonian and clastic sediments of the Lower Senonian. The Nezzazat Group has been divided ‎into four formations namely, from base to top, the Raha Formation, the Abu Qada Formation, ‎the Wata Formation and the Matulla Formation. The Cenomanian Raha and the Lower Senonian ‎Matulla formations are the most important clastic sequence in the Nezzazat Group because they ‎provide the highest net reservoir thickness and the highest net/gross ratio. This study emphasis ‎on Matulla formation located in the eastern part of the Gulf of Suez. The three stratigraphic ‎surface sections (Wadi Sudr, Wadi Matulla and Gabal Nezzazat) which represent the exposed ‎Coniacian-Santonian sediments in Sinai are used for correlating Matulla sediments of Ras ‎Budran field. Cutting description, petrographic examination, log behaviors, biostratigraphy with ‎outcrops are used to identify the reservoir characteristics, lithology, facies environment logs and ‎subdivide the Matulla formation into three units. The lower unit is believed to be the main ‎reservoir where it consists mainly of sands with shale and sandy carbonates, while the other ‎units are mainly carbonate with some streaks of shale and sand. Reservoir modeling is an ‎effective technique that assists in reservoir management as decisions concerning development ‎and depletion of hydrocarbon reserves, So It was essential to model the Matulla reservoir as ‎accurately as possible in order to better evaluate, calculate the reserves and to determine the ‎most effective way of recovering as much of the petroleum economically as possible. All ‎available data on Matulla formation are used to build the reservoir structure model, lithofacies, ‎porosity, permeability and water saturation models which are the main parameters that describe ‎the reservoirs and provide information on effective evaluation of the need to develop the oil ‎potentiality of the reservoir. This study has shown the effectiveness of; 1) the integration of ‎geological data to evaluate and subdivide Matulla formation into three units. 2) Lithology and ‎facies environment interpretation which helped in defining the nature of deposition of Matulla ‎formation. 3) The 3D reservoir modeling technology as a tool for adequate understanding of the ‎spatial distribution of property and in addition evaluating the unlocked new reservoir areas of ‎Matulla formation which have to be drilled to investigate and exploit the un-drained oil. 4) This ‎study led to adding a new room of production and additional reserves to Ras Budran field. ‎

Keywords: geology, oil and gas, geoscience, sequence stratigraphy

Procedia PDF Downloads 106
454 Monitoring the Effect of Doxorubicin Liposomal in VX2 Tumor Using Magnetic Resonance Imaging

Authors: Ren-Jy Ben, Jo-Chi Jao, Chiu-Ya Liao, Ya-Ru Tsai, Lain-Chyr Hwang, Po-Chou Chen

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Cancer is still one of the serious diseases threatening the lives of human beings. How to have an early diagnosis and effective treatment for tumors is a very important issue. The animal carcinoma model can provide a simulation tool for the study of pathogenesis, biological characteristics and therapeutic effects. Recently, drug delivery systems have been rapidly developed to effectively improve the therapeutic effects. Liposome plays an increasingly important role in clinical diagnosis and therapy for delivering a pharmaceutic or contrast agent to the targeted sites. Liposome can be absorbed and excreted by the human body, and is well known that no harm to the human body. This study aimed to compare the therapeutic effects between encapsulated (doxorubicin liposomal, LipoDox) and un-encapsulated (doxorubicin, Dox) anti-tumor drugs using Magnetic Resonance Imaging (MRI). Twenty-four New Zealand rabbits implanted with VX2 carcinoma at left thigh were classified into three groups: control group (untreated), Dox-treated group and LipoDox-treated group, 8 rabbits for each group. MRI scans were performed three days after tumor implantation. A 1.5T GE Signa HDxt whole body MRI scanner with a high resolution knee coil was used in this study. After a 3-plane localizer scan was performed, Three-Dimensional (3D) Fast Spin Echo (FSE) T2-Weighted Images (T2WI) was used for tumor volumetric quantification. And Two-Dimensional (2D) spoiled gradient recalled echo (SPGR) dynamic Contrast-enhanced (DCE) MRI was used for tumor perfusion evaluation. DCE-MRI was designed to acquire four baseline images, followed by contrast agent Gd-DOTA injection through the ear vein of rabbits. Afterwards, a series of 32 images were acquired to observe the signals change over time in the tumor and muscle. The MRI scanning was scheduled on a weekly basis for a period of four weeks to observe the tumor progression longitudinally. The Dox and LipoDox treatments were prescribed 3 times in the first week immediately after VX2 tumor implantation. ImageJ was used to quantitate tumor volume and time course signal enhancement on DCE images. The changes of tumor size showed that the growth of VX2 tumors was effectively inhibited for both LipoDox-treated and Dox-treated groups. Furthermore, the tumor volume of LipoDox-treated group was significantly lower than that of Dox-treated group, which implies that LipoDox has better therapeutic effect than Dox. The signal intensity of LipoDox-treated group is significantly lower than that of the other two groups, which implies that targeted therapeutic drug remained in the tumor tissue. This study provides a radiation-free and non-invasive MRI method for therapeutic monitoring of targeted liposome on an animal tumor model.

Keywords: doxorubicin, dynamic contrast-enhanced MRI, lipodox, magnetic resonance imaging, VX2 tumor model

Procedia PDF Downloads 457
453 Stability Assessment of Underground Power House Encountering Shear Zone: Sunni Dam Hydroelectric Project (382 MW), India

Authors: Sanjeev Gupta, Ankit Prabhakar, K. Rajkumar Singh

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Sunni Dam Hydroelectric Project (382 MW) is a run of river type development with an underground powerhouse, proposed to harness the hydel potential of river Satluj in Himachal Pradesh, India. The project is located in the inner lesser Himalaya between Dhauladhar Range in the south and the higher Himalaya in the north. The project comprises two large underground caverns, a Powerhouse cavern (171m long, 22.5m wide and 51.2m high) and another transformer hall cavern (175m long, 18.7m wide and 27m high) and the rock pillar between the two caverns is 50m. The highly jointed, fractured, anisotropic rock mass is a key challenge in Himalayan geology for an underground structure. The concern for the stability of rock mass increases when weak/shear zones are encountered in the underground structure. In the Sunni Dam project, 1.7m to 2m thick weak/shear zone comprising of deformed, weak material with gauge has been encountered in powerhouse cavern at 70m having dip direction 325 degree and dip amount 38 degree which also intersects transformer hall at initial reach. The rock encountered in the powerhouse area is moderate to highly jointed, pink quartz arenite belonging to the Khaira Formation, a transition zone comprising of alternate grey, pink & white quartz arenite and shale sequence and dolomite at higher reaches. The rock mass is intersected by mainly 3 joint sets excluding bedding joints and a few random joints. The rock class in powerhouse mainly varies from poor class (class IV) to lower order fair class (class III) and in some reaches, very poor rock mass has also been encountered. To study the stability of the underground structure in weak/shear rock mass, a 3D numerical model analysis has been carried out using RS3 software. Field studies have been interpreted and analysed to derive Bieniawski’s RMR, Barton’s “Q” class and Geological Strength Index (GSI). The various material parameters, in-situ characteristics have been determined based on tests conducted by Central Soil and Materials Research Station, New Delhi. The behaviour of the cavern has been studied by assessing the displacement contours, major and minor principal stresses and plastic zones for different stage excavation sequences. For optimisation of the support system, the stability of the powerhouse cavern with different powerhouse orientations has also been studied. The numerical modeling results indicate that cavern will not likely face stress governed by structural instability with the support system to be applied to the crown and side walls.

Keywords: 3D analysis, Himalayan geology, shear zone, underground power house

Procedia PDF Downloads 88
452 Measurement of Influence of the COVID-19 Pandemic on Efficiency of Japan’s Railway Companies

Authors: Hideaki Endo, Mika Goto

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The global outbreak of the COVID-19 pandemic has seriously affected railway businesses. The number of railway passengers decreased due to the decline in the number of commuters and business travelers to avoid crowded trains and a sharp drop in inbound tourists visiting Japan. This has affected not only railway businesses but also related businesses, including hotels, leisure businesses, and retail businesses at station buildings. In 2021, the companies were divided into profitable and loss-making companies. This division suggests that railway companies, particularly loss-making companies, needed to decrease operational inefficiency. To measure the impact of COVID-19 and discuss the sustainable management strategies of railway companies, we examine the cost inefficiency of Japanese listed railway companies by applying stochastic frontier analysis (SFA) to their operational and financial data. First, we employ the stochastic frontier cost function approach to measure inefficiency. The cost frontier function is formulated as a Cobb–Douglas type, and we estimated parameters and variables for inefficiency. This study uses panel data comprising 26 Japanese-listed railway companies from 2005 to 2020. This period includes several events deteriorating the business environment, such as the financial crisis from 2007 to 2008 and the Great East Japan Earthquake of 2011, and we compare those impacts with those of the COVID-19 pandemic after 2020. Second, we identify the characteristics of the best-practice railway companies and examine the drivers of cost inefficiencies. Third, we analyze the factors influencing cost inefficiency by comparing the profiles of the top 10 railway companies and others before and during the pandemic. Finally, we examine the relationship between cost inefficiency and the implementation of efficiency measures for each railway company. We obtained the following four findings. First, most Japanese railway companies showed the lowest cost inefficiency (most efficient) in 2014 and the highest in 2020 (least efficient) during the COVID-19 pandemic. The second worst occurred in 2009 when it was affected by the financial crisis. However, we did not observe a significant impact of the 2011 Great East Japan Earthquake. This is because no railway company was influenced by the earthquake in this operating area, except for JR-EAST. Second, the best-practice railway companies are KEIO and TOKYU. The main reason for their good performance is that both operate in and near the Tokyo metropolitan area, which is densely populated. Third, we found that non-best-practice companies had a larger decrease in passenger kilometers than best-practice companies. This indicates that passengers made fewer long-distance trips because they refrained from inter-prefectural travel during the pandemic. Finally, we found that companies that implement more efficiency improvement measures had higher cost efficiency and they effectively used their customer databases through proactive DX investments in marketing and asset management.

Keywords: COVID-19 pandemic, stochastic frontier analysis, railway sector, cost efficiency

Procedia PDF Downloads 74
451 Spectroscopic Autoradiography of Alpha Particles on Geologic Samples at the Thin Section Scale Using a Parallel Ionization Multiplier Gaseous Detector

Authors: Hugo Lefeuvre, Jerôme Donnard, Michael Descostes, Sophie Billon, Samuel Duval, Tugdual Oger, Herve Toubon, Paul Sardini

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Spectroscopic autoradiography is a method of interest for geological sample analysis. Indeed, researchers may face different issues such as radioelement identification and quantification in the field of environmental studies. Imaging gaseous ionization detectors find their place in geosciences for conducting specific measurements of radioactivity to improve the monitoring of natural processes using naturally-occurring radioactive tracers, but also for the nuclear industry linked to the mining sector. In geological samples, the location and identification of the radioactive-bearing minerals at the thin-section scale remains a major challenge as the detection limit of the usual elementary microprobe techniques is far higher than the concentration of most of the natural radioactive decay products. The spatial distribution of each decay product in the case of uranium in a geomaterial is interesting for relating radionuclides concentration to the mineralogy. The present study aims to provide spectroscopic autoradiography analysis method for measuring the initial energy of alpha particles with a parallel ionization multiplier gaseous detector. The analysis method has been developed thanks to Geant4 modelling of the detector. The track of alpha particles recorded in the gas detector allow the simultaneous measurement of the initial point of emission and the reconstruction of the initial particle energy by a selection based on the linear energy distribution. This spectroscopic autoradiography method was successfully used to reproduce the alpha spectra from a 238U decay chain on a geological sample at the thin-section scale. The characteristics of this measurement are an energy spectrum resolution of 17.2% (FWHM) at 4647 keV and a spatial resolution of at least 50 µm. Even if the efficiency of energy spectrum reconstruction is low (4.4%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area. This opens up possibilities for the detailed analysis of heterogeneous geological samples containing natural alpha emitters such as uranium-238 and radium-226. This measurement will allow the study of the spatial distribution of uranium and its descendants in geo-materials by coupling scanning electron microscope characterizations. The direct application of this dual modality (energy-position) of analysis will be the subject of future developments. The measurement of the radioactive equilibrium state of heterogeneous geological structures, and the quantitative mapping of 226Ra radioactivity are now being actively studied.

Keywords: alpha spectroscopy, digital autoradiography, mining activities, natural decay products

Procedia PDF Downloads 151
450 Preparation of Activated Carbon From Waste Feedstock: Activation Variables Optimization and Influence

Authors: Oluwagbemi Victor Aladeokin

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In the last decade, the global peanut cultivation has seen increased demand, which is attributed to their health benefits, rising to ~ 41.4 MMT in 2019/2020. Peanut and other nutshells are considered as waste in various parts of the world and are usually used for their fuel value. However, this agricultural by-product can be converted to a higher value product such as activated carbon. For many years, due to the highly porous structure of activated carbon, it has been widely and effectively used as an adsorbent in the purification and separation of gases and liquids. Those used for commercial purposes are primarily made from a range of precursors such as wood, coconut shell, coal, bones, etc. However, due to difficulty in regeneration and high cost, various agricultural residues such as rice husk, corn stalks, apricot stones, almond shells, coffee beans, etc, have been explored to produce activated carbons. In the present study, the potential of peanut shells as precursors in the production of activated carbon and their adsorption capacity is investigated. Usually, precursors used to produce activated carbon have carbon content above 45 %. A typical raw peanut shell has 42 wt.% carbon content. To increase the yield, this study has employed chemical activation method using zinc chloride. Zinc chloride is well known for its effectiveness in increasing porosity of porous carbonaceous materials. In chemical activation, activation temperature and impregnation ratio are parameters commonly reported to be the most significant, however, this study has also studied the influence of activation time on the development of activated carbon from peanut shells. Activated carbons are applied for different purposes, however, as the application of activated carbon becomes more specific, an understanding of the influence of activation variables to have a better control of the quality of the final product becomes paramount. A traditional approach to experimentally investigate the influence of the activation parameters, involves varying each parameter at a time. However, a more efficient way to reduce the number of experimental runs is to apply design of experiment. One of the objectives of this study is to optimize the activation variables. Thus, this work has employed response surface methodology of design of experiment to study the interactions between the activation parameters and consequently optimize the activation parameters (temperature, impregnation ratio, and activation time). The optimum activation conditions found were 485 °C, 15 min and 1.7, temperature, activation time, and impregnation ratio respectively. The optimum conditions resulted in an activated carbon with relatively high surface area ca. 1700 m2/g, 47 % yield, relatively high density, low ash, and high fixed carbon content. Impregnation ratio and temperature were found to mostly influence the final characteristics of the produced activated carbon from peanut shells. The results of this study, using response surface methodology technique, have revealed the potential and the most significant parameters that influence the chemical activation process, of peanut shells to produce activated carbon which can find its use in both liquid and gas phase adsorption applications.

Keywords: chemical activation, fixed carbon, impregnation ratio, optimum, surface area

Procedia PDF Downloads 145
449 Effects of Virtual Reality Treadmill Training on Gait and Balance Performance of Patients with Stroke: Review

Authors: Hanan Algarni

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Background: Impairment of walking and balance skills has negative impact on functional independence and community participation after stroke. Gait recovery is considered a primary goal in rehabilitation by both patients and physiotherapists. Treadmill training coupled with virtual reality technology is a new emerging approach that offers patients with feedback, open and random skills practice while walking and interacting with virtual environmental scenes. Objectives: To synthesize the evidence around the effects of the VR treadmill training on gait speed and balance primarily, functional independence and community participation secondarily in stroke patients. Methods: Systematic review was conducted; search strategy included electronic data bases: MEDLINE, AMED, Cochrane, CINAHL, EMBASE, PEDro, Web of Science, and unpublished literature. Inclusion criteria: Participant: adult >18 years, stroke, ambulatory, without severe visual or cognitive impartments. Intervention: VR treadmill training alone or with physiotherapy. Comparator: any other interventions. Outcomes: gait speed, balance, function, community participation. Characteristics of included studies were extracted for analysis. Risk of bias assessment was performed using Cochrane's ROB tool. Narrative synthesis of findings was undertaken and summary of findings in each outcome was reported using GRADEpro. Results: Four studies were included involving 84 stroke participants with chronic hemiparesis. Interventions intensity ranged (6-12 sessions, 20 minutes-1 hour/session). Three studies investigated the effects on gait speed and balance. 2 studies investigated functional outcomes and one study assessed community participation. ROB assessment showed 50% unclear risk of selection bias and 25% of unclear risk of detection bias across the studies. Heterogeneity was identified in the intervention effects at post training and follow up. Outcome measures, training intensity and durations also varied across the studies, grade of evidence was low for balance, moderate for speed and function outcomes, and high for community participation. However, it is important to note that grading was done on few numbers of studies in each outcome. Conclusions: The summary of findings suggests positive and statistically significant effects (p<0.05) of VR treadmill training compared to other interventions on gait speed, dynamic balance skills, function and participation directly after training. However, the effects were not sustained at follow up in two studies (2 weeks-1 month) and other studies did not perform follow up measurements. More RCTs with larger sample sizes and higher methodological quality are required to examine the long term effects of VR treadmill effects on function independence and community participation after stroke, in order to draw conclusions and produce stronger robust evidence.

Keywords: virtual reality, treadmill, stroke, gait rehabilitation

Procedia PDF Downloads 274
448 Understanding the Impact of Out-of-Sequence Thrust Dynamics on Earthquake Mitigation: Implications for Hazard Assessment and Disaster Planning

Authors: Rajkumar Ghosh

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Earthquakes pose significant risks to human life and infrastructure, highlighting the importance of effective earthquake mitigation strategies. Traditional earthquake modelling and mitigation efforts have largely focused on the primary fault segments and their slip behaviour. However, earthquakes can exhibit complex rupture dynamics, including out-of-sequence thrust (OOST) events, which occur on secondary or subsidiary faults. This abstract examines the impact of OOST dynamics on earthquake mitigation strategies and their implications for hazard assessment and disaster planning. OOST events challenge conventional seismic hazard assessments by introducing additional fault segments and potential rupture scenarios that were previously unrecognized or underestimated. Consequently, these events may increase the overall seismic hazard in affected regions. The study reviews recent case studies and research findings that illustrate the occurrence and characteristics of OOST events. It explores the factors contributing to OOST dynamics, such as stress interactions between fault segments, fault geometry, and mechanical properties of fault materials. Moreover, it investigates the potential triggers and precursory signals associated with OOST events to enhance early warning systems and emergency response preparedness. The abstract also highlights the significance of incorporating OOST dynamics into seismic hazard assessment methodologies. It discusses the challenges associated with accurately modelling OOST events, including the need for improved understanding of fault interactions, stress transfer mechanisms, and rupture propagation patterns. Additionally, the abstract explores the potential for advanced geophysical techniques, such as high-resolution imaging and seismic monitoring networks, to detect and characterize OOST events. Furthermore, the abstract emphasizes the practical implications of OOST dynamics for earthquake mitigation strategies and urban planning. It addresses the need for revising building codes, land-use regulations, and infrastructure designs to account for the increased seismic hazard associated with OOST events. It also underscores the importance of public awareness campaigns to educate communities about the potential risks and safety measures specific to OOST-induced earthquakes. This sheds light on the impact of out-of-sequence thrust dynamics in earthquake mitigation. By recognizing and understanding OOST events, researchers, engineers, and policymakers can improve hazard assessment methodologies, enhance early warning systems, and implement effective mitigation measures. By integrating knowledge of OOST dynamics into urban planning and infrastructure development, societies can strive for greater resilience in the face of earthquakes, ultimately minimizing the potential for loss of life and infrastructure damage.

Keywords: earthquake mitigation, out-of-sequence thrust, seismic, satellite imagery

Procedia PDF Downloads 88
447 White Individuals' Perception On Whiteness

Authors: Sebastian Del Corral Winder, Kiriana Sanchez, Mixalis Poulakis, Samantha Gray

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This paper seeks to explore White privilege and Whiteness. Being White in the U.S. is often perceived as the norm and it brings significant social, economic, educational, and health privileges that often are hidden in social interactions. One quality of Whiteness has been its invisibility given its intrinsic impact on the system, which becomes only visible when paying close attention to White identity and culture and during cross-cultural interactions. The cross-cultural interaction provides an emphasis on differences between the participants and people of color are often viewed as “the other.” These interactions may promote an increased opportunity for discrimination and negative stereotypes against a person of color. Given the recent increase of violence against culturally diverse groups, there has been an increased sense of otherness and division in the country. Furthermore, the accent prestige theory has found that individuals who speak English with a foreign accent are perceived as less educated, competent, friendly, and trustworthy by White individuals in the United States. Using the consensual qualitative research (CQR) methodology, this study explored the cross-cultural dyad from the White individual’s perspective focusing on the psychotherapeutic relationship. The participants were presented with an audio recording of a conversation between a psychotherapist with a Hispanic accent and a patient with an American English accent. Then, the participants completed an interview regarding their perceptions of race, culture, and cross-cultural interactions. The preliminary results suggested that the Hispanic accent alone was enough for the participants to assign stereotypical ethnic and cultural characteristics to the individual with the Hispanic accent. Given the quality of the responses, the authors completed a secondary analysis to explore Whiteness and White privilege in more depth. Participants were found to be on a continuum in their understanding and acknowledgment of systemic racism; while some participants listed examples of inequality, other participants noted: “all people are treated equally.” Most participants noted their feelings of discomfort in discussing topics of cultural diversity and systemic racism by fearing to “say the ‘wrong thing.” Most participants placed the responsibility of discussing cultural differences with the person of color, which has been observed to create further alienation and otherness for culturally diverse individuals. The results indicate the importance of examining racial and cultural biases from White individuals to promote an anti-racist stance. The results emphasize the need for greater systemic changes in education, policies, and individual awareness regarding cultural identity. The results suggest the importance for White individuals to take ownership of their own cultural biases in order to promote equity and engage in cultural humility in a multicultural world. Future research should continue exploring the role of White ethnic identity and education as they appear to moderate White individuals’ attitudes and beliefs regarding other races and cultures.

Keywords: culture, qualitative research, whiteness, white privilege

Procedia PDF Downloads 158
446 The Role of Structural Poverty in the Know-How and Moral Economy of Doctors in Africa: An Anthropological Perspective

Authors: Isabelle Gobatto

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Based on an anthropological approach, this paper explores the medical profession and the construction of medical practices by considering the multiform articulations between structural poverty and the production of care from a low-resource francophone West African country, Burkina Faso. This country is considered in its exemplary dimension of culturally differentiated countries of the African continent that share the same situation of structural poverty. The objective is to expose the effects of structural poverty on the ways of constructing professional knowledge and thinking about the sense of the medical profession. If doctors are trained to have the same capacities in South and West countries, which are to treat and save lives whatever the cultural contexts of the practice of medicine, the ways of investing their role and of dealing with this context of action fracture the homogenization of the medical profession. In the line of anthropology of biomedicine, this paper outlines the complex effects of structural poverty on health care, care relations, and the moral economy of doctors. The materials analyzed are based on an ethnography including two temporalities located thirty years apart (1990-1994 and 2020-2021), based on long-term observations of care practices conducted in healthcare institutions, interviews coupled with the life histories of physicians. The findings reveal that disabilities faced by doctors to deliver care are interpreted as policy gaps, but they are also considered by physicians as constitutive of the social and cultural characteristics of patients, making their capacities and incapacities in terms of accompanying caregivers in the production of care. These perceptions have effects on know-how, structured around the need to act even when diagnoses are not made so as not to see patients desert health structures if the costs of care are too high for them. But these interpretations of highly individualizing dimensions of these difficulties place part of the blame on patients for the difficulties in using learned knowledge and delivering effective care. These situations challenge the ethics of caregivers but also of ethnologists. Firstly because the interpretations of disabilities prevent caregivers from considering vulnerabilities of care as constituting a common condition shared with their patients in these health systems, affecting them in an identical way although in different places in the production of care. Correlatively, these results underline that these professional conceptions prevent the emergence of a figure of victim, which could be shared between patients and caregivers who, together, undergo working and care conditions at the limit of the acceptable. This dimension directly involves politics. Secondly, structural poverty and its effects on care challenge the ethics of the anthropologist who observes caregivers producing, without intent to arm, experiences of care marked by an ordinary violence, by not giving them the care they need. It is worth asking how anthropologists could get doctors to think in this light in west-African societies.

Keywords: Africa, care, ethics, poverty

Procedia PDF Downloads 69
445 Threats to the Business Value: The Case of Mechanical Engineering Companies in the Czech Republic

Authors: Maria Reznakova, Michala Strnadova, Lukas Reznak

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Successful achievement of strategic goals requires an effective performance management system, i.e. determining the appropriate indicators measuring the rate of goal achievement. Assuming that the goal of the owners is to grow the assets they invested in, it is vital to identify the key performance indicators, which contribute to value creation. These indicators are known as value drivers. Based on the undertaken literature search, a value driver is defined as any factor that affects the value of an enterprise. The important factors are then monitored by both financial and non-financial indicators. Financial performance indicators are most useful in strategic management, since they indicate whether a company's strategy implementation and execution are contributing to bottom line improvement. Non-financial indicators are mainly used for short-term decisions. The identification of value drivers, however, is problematic for companies which are not publicly traded. Therefore financial ratios continue to be used to measure the performance of companies, despite their considerable criticism. The main drawback of such indicators is the fact that they are calculated based on accounting data, while accounting rules may differ considerably across different environments. For successful enterprise performance management it is vital to avoid factors that may reduce (or even destroy) its value. Among the known factors reducing the enterprise value are the lack of capital, lack of strategic management system and poor quality of production. In order to gain further insight into the topic, the paper presents results of the research identifying factors that adversely affect the performance of mechanical engineering enterprises in the Czech Republic. The research methodology focuses on both the qualitative and the quantitative aspect of the topic. The qualitative data were obtained from a questionnaire survey of the enterprises senior management, while the quantitative financial data were obtained from the Analysis Major Database for European Sources (AMADEUS). The questionnaire prompted managers to list factors which negatively affect business performance of their enterprises. The range of potential factors was based on a secondary research – analysis of previously undertaken questionnaire surveys and research of studies published in the scientific literature. The results of the survey were evaluated both in general, by average scores, and by detailed sub-analyses of additional criteria. These include the company specific characteristics, such as its size and ownership structure. The evaluation also included a comparison of the managers’ opinions and the performance of their enterprises – measured by return on equity and return on assets ratios. The comparisons were tested by a series of non-parametric tests of statistical significance. The results of the analyses show that the factors most detrimental to the enterprise performance include the incompetence of responsible employees and the disregard to the customers‘ requirements.

Keywords: business value, financial ratios, performance measurement, value drivers

Procedia PDF Downloads 222
444 Socio-Cultural Economic and Demographic Profile of Return Migration: A Case Study of Mahaboobnagar District in ‘Andhra Pradesh’

Authors: Ramanamurthi Botlagunta

Abstract:

Return migrate on is a process; it’s not a new phenomenal. People are migrating since civilization started. In the case of Indian Diaspora, peoples migrated before the Independence of India. Even after the independence. There are various reasons for the migration. According to the characteristics of the migrants, geographical, political, and economic factors there are many changes occur in the mode of migration. In India currently almost 25 million peoples are outside of the country. But all of them not able to get the immigrants status in their respective host society due to the nature of individual perception and the immigration policies of the host countries. They came back to homeland after spending days/months/years. They are known as the return migrants. Returning migrants are 'persons returning to their country of citizenship after having been international migrants, whether short term or long-term'. Increasingly, migration is seen very differently from what was once believed to be a one-way phenomenon. The renewed interest of return migration can be seen through two aspects one is that growing importance of temporary migration programmers in other countries and other one is that potential role of migrants in developing their home countries. Conceptualized return migration in several ways: occasional return, seasonal return, temporary return, permanent return, and circular return. The reasons for the return migration are retirement, failure to assimilate in the host country, problems with acculturation in the destination country, being unsuccessful in the emigrating country, acquiring the desired wealth, innovate and to serve as change agents in the birth country. With the advent of globalization and the rapid development of transportation systems and communication technologies, this is a process by which immigrants forge and sustain simultaneous multi-stranded social relations that link together their societies of origin and settlement. We can find that Current theories of transnational migration are greatly focused on the economic impacts on the home countries, while social, cultural and political impacts have recently started gaining momentum. This, however, has been changing as globalization is radically transforming the way people move around the world. One of the reasons for the return migration is that lack of proportionate representation of Asian immigrants in positions of authority and decision-making can be a result of challenges confronted in cultural and structural assimilation. The present study mainly focuses socioeconomic and demographic profile of return migration of Indians from other countries in general and particularly on Andhra Pradesh the people who are returning from other countries. Migration is that lack of proportionate representation of Asian immigrants in positions of authority and decision-making can be a result of challenges confronted in cultural and structural assimilation. The present study mainly focuses socioeconomic and demographic profile of return migration of Indians from other countries in general and particularly on Andhra Pradesh the people who are returning from other countries.

Keywords: migration, return migration, globalization, development, socio- economic, Asian immigrants, UN, Andhra Pradesh

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443 The Charge Exchange and Mixture Formation Model in the ASz-62IR Radial Aircraft Engine

Authors: Pawel Magryta, Tytus Tulwin, Paweł Karpiński

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The ASz62IR engine is a radial aircraft engine with 9 cylinders. This object is produced by the Polish company WSK "PZL-KALISZ" S.A. This is engine is currently being developed by the above company and Lublin University of Technology. In order to provide an effective work of the technological development of this unit it was decided to made the simulation model. The model of ASz-62IR was developed with AVL BOOST software which is a tool dedicated to the one-dimensional modeling of internal combustion engines. This model can be used to calculate parameters of an air and fuel flow in an intake system including charging devices as well as combustion and exhaust flow to the environment. The main purpose of this model is the analysis of the charge exchange and mixture formation in this engine. For this purpose, the model consists of elements such: as air inlet, throttle system, compressor connector, charging compressor, inlet pipes and injectors, outlet pipes, fuel injection and model of fuel mixing and evaporation. The model of charge exchange and mixture formation was based on the model of mass flow rate in intake and exhaust pipes, and also on the calculation of gas properties values like gas constant or thermal capacity. This model was based on the equations to describe isentropic flow. The energy equation to describe flow under steady conditions was transformed into the mass flow equation. In the model the flow coefficient μσ was used, that varies with the stroke/valve opening and was determined in a steady flow state. The geometry of the inlet channels and other key components was mapped with reference to the technical documentation of the engine and empirical measurements of the structure elements. The volume of elements on the charge flow path between the air inlet and the exhaust outlet was measured by the CAD mapping of the structure. Taken from the technical documentation, the original characteristics of the compressor engine was entered into the model. Additionally, the model uses a general model for the transport of chemical compounds of the mixture. There are 7 compounds used, i.e. fuel, O2, N2, CO2, H2O, CO, H2. A gasoline fuel of a calorific value of 43.5 MJ/kg and an air mass fraction for stoichiometric mixture of 14.5 were used. Indirect injection into the intake manifold is used in this model. The model assumes the following simplifications: the mixture is homogenous at the beginning of combustion, accordingly, mixture stoichiometric coefficient A/F remains constant during combustion, combusted and non-combusted charges show identical pressures and temperatures although their compositions change. As a result of the simulation studies based on the model described above, the basic parameters of combustion process, charge exchange, mixture formation in cylinders were obtained. The AVL Boost software is very useful for the piston engine performance simulations. This work has been financed by the Polish National Centre for Research and Development, INNOLOT, under Grant Agreement No. INNOLOT/I/1/NCBR/2013.

Keywords: aviation propulsion, AVL Boost, engine model, charge exchange, mixture formation

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442 Petrology, Geochemistry and Formation Conditions of Metaophiolites of the Loki Crystalline Massif (the Caucasus)

Authors: Irakli Gamkrelidze, David Shengelia, Tamara Tsutsunava, Giorgi Chichinadze, Giorgi Beridze, Ketevan Tedliashvili, Tamara Tsamalashvili

Abstract:

The Loki crystalline massif crops out in the Caucasian region and the geological retrospective represent the northern marginal part of the Baiburt-Sevanian terrain (island arc), bordering with the Paleotethys oceanic basin in the north. The pre-Alpine basement of the massif is built up of Lower-Middle Paleozoic metamorphic complex (metasedimentary and metabasite rocks), Upper Devonian quartz-diorites and Late Variscan granites. Earlier metamorphic complex was considered as an indivisible set including suites with different degree of metamorphism. Systematic geologic, petrologic and geochemical investigations of the massif’s rocks suggest the different conception on composition, structure and formation conditions of the massif. In particular, there are two main rock types in the Loki massif: the oldest autochthonous series of gneissic quartz-diorites and cutting them granites. The massif is flanked on its western side by a volcano-sedimentary sequence, metamorphosed to low-T facies. Petrologic, metamorphic and structural differences in this sequence prove the existence of a number of discrete units (overthrust sheets). One of them, the metabasic sheet represents the fragment of ophiolite complex. It comprises transition types of the second and third layers of the Paleooceanic crust: the upper noncumulated part of the third layer gabbro component and the following lowest part of the parallel diabase dykes of the second layer. The ophiolites are represented by metagabbros, metagabbro-diabases, metadiabases and amphibolite schists. According to the content of petrogenic components and additive elements in metabasites is stated that the protolith of metabasites belongs to petrochemical type of tholeiitic series of basalts. The parental magma of metaophiolites is of E-MORB composition, and by petrochemical parameters, it is very close to the composition of intraplate basalts. The dykes of hypabissal leucocratic siliceous and medium magmatic rocks associated with the metaophiolite sheet form the separate complex. They are granitoids with the extremely low content of CaO and quartz-diorite porphyries. According to various petrochemical parameters, these rocks have mixed characteristics. Their formation took place in spreading conditions or in the areas of manifestation of plumes most likely of island arc type. The metamorphism degree of the metaophiolites corresponds to a very low stage of green schist facies. The rocks of the metaophiolite complex are obducted from the Paleotethys Ocean. Geological and paleomagnetic data show that the primary location of the ocean is supposed to be to the north of the Loki crystalline massif.

Keywords: the Caucasus, crystalline massif, ophiolites, tectonic sheet

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441 Assessment of Taiwan Railway Occurrences Investigations Using Causal Factor Analysis System and Bayesian Network Modeling Method

Authors: Lee Yan Nian

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Safety investigation is different from an administrative investigation in that the former is conducted by an independent agency and the purpose of such investigation is to prevent accidents in the future and not to apportion blame or determine liability. Before October 2018, Taiwan railway occurrences were investigated by local supervisory authority. Characteristics of this kind of investigation are that enforcement actions, such as administrative penalty, are usually imposed on those persons or units involved in occurrence. On October 21, 2018, due to a Taiwan Railway accident, which caused 18 fatalities and injured another 267, establishing an agency to independently investigate this catastrophic railway accident was quickly decided. The Taiwan Transportation Safety Board (TTSB) was then established on August 1, 2019 to take charge of investigating major aviation, marine, railway and highway occurrences. The objective of this study is to assess the effectiveness of safety investigations conducted by the TTSB. In this study, the major railway occurrence investigation reports published by the TTSB are used for modeling and analysis. According to the classification of railway occurrences investigated by the TTSB, accident types of Taiwan railway occurrences can be categorized into: derailment, fire, Signal Passed at Danger and others. A Causal Factor Analysis System (CFAS) developed by the TTSB is used to identify the influencing causal factors and their causal relationships in the investigation reports. All terminologies used in the CFAS are equivalent to the Human Factors Analysis and Classification System (HFACS) terminologies, except for “Technical Events” which was added to classify causal factors resulting from mechanical failure. Accordingly, the Bayesian network structure of each occurrence category is established based on the identified causal factors in the CFAS. In the Bayesian networks, the prior probabilities of identified causal factors are obtained from the number of times in the investigation reports. Conditional Probability Table of each parent node is determined from domain experts’ experience and judgement. The resulting networks are quantitatively assessed under different scenarios to evaluate their forward predictions and backward diagnostic capabilities. Finally, the established Bayesian network of derailment is assessed using investigation reports of the same accident which was investigated by the TTSB and the local supervisory authority respectively. Based on the assessment results, findings of the administrative investigation is more closely tied to errors of front line personnel than to organizational related factors. Safety investigation can identify not only unsafe acts of individual but also in-depth causal factors of organizational influences. The results show that the proposed methodology can identify differences between safety investigation and administrative investigation. Therefore, effective intervention strategies in associated areas can be better addressed for safety improvement and future accident prevention through safety investigation.

Keywords: administrative investigation, bayesian network, causal factor analysis system, safety investigation

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440 The Improved Therapeutic Effect of Trans-Cinnamaldehyde on Adipose-Derived Stem Cells without Chemical Induction

Authors: Karthyayani Rajamani, Yi-Chun Lin, Tung-Chou Wen, Jeanne Hsieh, Yi-Maun Subeq, Jen-Wei Liu, Po-Cheng Lin, Horng-Jyh Harn, Shinn-Zong Lin, Tzyy-Wen Chiou

Abstract:

Assuring cell quality is an essential parameter for the success of stem cell therapy, utilization of various components to improve this potential has been the primary goal of stem cell research. The aim of this study was not only to demonstrate the capacity of trans-cinnamaldehyde (TC) to reverse stress-induced senescence but also improve the therapeutic abilities of stem cells. Because of the availability and the promising application potential in regenerative medicine, adipose-derived stem cells (ADSCs) were chosen for the study. We found that H2O2 treatment resulted in the expression of senescence characteristics in the ADSCs, including decreased proliferation rate, increased senescence-associated- β-galactosidase (SA-β-gal) activity, decreased SIRT1 (silent mating type information regulation 2 homologs) expression and decreased telomerase activity. However, TC treatment was sufficient to rescue or reduce the effects of H2O2 induction, ultimately leading to an increased proliferation rate, a decrease in the percentage of SA-β-gal positive cells, upregulation of SIRT1 expression, and increased telomerase activity of the senescent ADSCs at the cellular level. Further recently it was observed that the ADSCs were treated with TC without induction of senescence, all the before said positives were observed. Moreover, a chemically induced liver fibrosis animal model was used to evaluate the functionality of these rescued cells in vivo. Liver dysfunction was established by injecting 200 mg/kg thioacetamide (TAA) intraperitoneally into Wistar rats every third day for 60 days. The experimental rats were separated into groups; normal group (rats without TAA induction), sham group (without ADSC transplantation), positive control group (transplanted with normal ADSCs); H2O2 group (transplanted with H2O2 -induced senescent ADSCs), H2O2+TC group (transplanted with ADSCs pretreated with H2O2 and then further treated with TC) and TC group (ADSC treated with TC without H2O2 treatment). In the transplantation group, 1 × 106 human ADSCs were introduced into each rat via direct liver injection. Based on the biochemical analysis and immunohistochemical staining results, it was determined that the therapeutic effects on liver fibrosis by the induced senescent ADSCs (H2O2 group) were not as significant as those exerted by the normal ADSCs (the positive control group). However, the H2O2+TC group showed significant reversal of liver damage when compared to the H2O2 group 1 week post-transplantation. Further ADSCs without H2O2 treatment but with just TC treatment performed much better than all the groups. These data confirmed that the TC treatment had the potential to improve the therapeutic effect of ADSCs. It is therefore suggested that TC has potential applications in maintaining stem cell quality and could possibly aid in the treatment of senescence-related disorders.

Keywords: senescence, SIRT1, adipose derived stem cells, liver fibrosis

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439 The Dynamics of a Droplet Spreading on a Steel Surface

Authors: Evgeniya Orlova, Dmitriy Feoktistov, Geniy Kuznetsov

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Spreading of a droplet over a solid substrate is a key phenomenon observed in the following engineering applications: thin film coating, oil extraction, inkjet printing, and spray cooling of heated surfaces. Droplet cooling systems are known to be more effective than film or rivulet cooling systems. It is caused by the greater evaporation surface area of droplets compared with the film of the same mass and wetting surface. And the greater surface area of droplets is connected with the curvature of the interface. Location of the droplets on the cooling surface influences on the heat transfer conditions. The close distance between the droplets provides intensive heat removal, but there is a possibility of their coalescence in the liquid film. The long distance leads to overheating of the local areas of the cooling surface and the occurrence of thermal stresses. To control the location of droplets is possible by changing the roughness, structure and chemical composition of the surface. Thus, control of spreading can be implemented. The most important characteristic of spreading of droplets on solid surfaces is a dynamic contact angle, which is a function of the contact line speed or capillary number. However, there is currently no universal equation, which would describe the relationship between these parameters. This paper presents the results of the experimental studies of water droplet spreading on metal substrates with different surface roughness. The effect of the droplet growth rate and the surface roughness on spreading characteristics was studied at low capillary numbers. The shadow method using high speed video cameras recording up to 10,000 frames per seconds was implemented. A droplet profile was analyzed by Axisymmetric Drop Shape Analyses techniques. According to change of the dynamic contact angle and the contact line speed three sequential spreading stages were observed: rapid increase in the dynamic contact angle; monotonous decrease in the contact angle and the contact line speed; and form of the equilibrium contact angle at constant contact line. At low droplet growth rate, the dynamic contact angle of the droplet spreading on the surfaces with the maximum roughness is found to increase throughout the spreading time. It is due to the fact that the friction force on such surfaces is significantly greater than the inertia force; and the contact line is pinned on microasperities of a relief. At high droplet growth rate the contact angle decreases during the second stage even on the surfaces with the maximum roughness, as in this case, the liquid does not fill the microcavities, and the droplet moves over the “air cushion”, i.e. the interface is a liquid/gas/solid system. Also at such growth rates pulsation of liquid flow was detected; and the droplet oscillates during the spreading. Thus, obtained results allow to conclude that it is possible to control spreading by using the surface roughness and the growth rate of droplets on surfaces as varied factors. Also, the research findings may be used for analyzing heat transfer in rivulet and drop cooling systems of high energy equipment.

Keywords: contact line speed, droplet growth rate, dynamic contact angle, shadow system, spreading

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