Search results for: free space optics

Authors: Xin Li, Zhenxue Jiang, Zhuo Li

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Generally, shale gas is trapped within shale systems with low porosity and ultralow permeability as free and adsorbing states. Its production is controlled by properties, in terms of occurrence phases, gas contents, and percolation characteristics. These properties are all influenced by porous features. In this paper, porosity differences of marine shales were explored between Lower Cambrian shale and Lower Silurian shale of Sichuan Basin, South China. Both the two shales were marine shales with abundant oil-prone kerogen and rich siliceous minerals. Whereas Lower Cambrian shale (3.56% Ro) possessed a higher thermal degree than that of Lower Silurian shale (2.31% Ro). Samples were measured by a combination of organic-chemistry geology measurement, organic matter (OM) isolation, X-ray diffraction (XRD), N2 adsorption, and focused ion beam milling and scanning electron microscopy (FIB-SEM). Lower Cambrian shale presented relatively low pore properties, with averaging 0.008ml/g pore volume (PV), averaging 7.99m²/g pore surface area (PSA) and averaging 5.94nm average pore diameter (APD). Lower Silurian shale showed as relatively high pore properties, with averaging 0.015ml/g PV, averaging 10.53m²/g PSA and averaging 18.60nm APD. Additionally, fractal analysis indicated that the two shales presented discrepant pore morphologies, mainly caused by differences in the combination of pore types between the two shales. More specifically, OM-hosted pores with pin-hole shape and dissolved pores with dead-end openings were the main types in Lower Cambrian shale, while OM-hosted pore with a cellular structure was the main type in Lower Silurian shale. Moreover, porous characteristics of isolated OM suggested that OM of Lower Silurian shale was more capable than that of Lower Cambrian shale in the aspect of pore contribution. PV of isolated OM in Lower Silurian shale was almost 6.6 times higher than that in Lower Cambrian shale, and PSA of isolated OM in Lower Silurian shale was almost 4.3 times higher than that in Lower Cambrian shale. However, no apparent differences existed among samples with various matrix compositions. At late diagenetic or metamorphic epoch, extensive diagenesis overprints the effects of minerals on pore properties and OM plays the dominant role in pore developments. Hence, differences of porous features between the two marine shales highlight the effect of diagenetic degree on OM-hosted pore development. Consequently, distinctive pore characteristics may be caused by the different degrees of diagenetic evolution, even with similar matrix basics.

Keywords: marine shale, lower Cambrian, lower Silurian, om isolation, pore properties, om-hosted pore

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Authors: Anamika Sahu

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The Himalayas, like many mountainous regions, is susceptible to multiple hazards. In recent times, the frequency of such disasters is continuously increasing due to extreme weather phenomena. These natural hazards are responsible for irreparable human and economic loss. The Indian Himalayas has repeatedly been ruptured by great earthquakes in the past and has the potential for a future large seismic event as it falls under the seismic gap. Damages caused by earthquakes are different in different localities. It is well known that, during earthquakes, damage to the structure is associated with the subsurface conditions and the quality of construction materials. So, for sustainable mountain development, prior estimation of site characterization will be valuable for designing and constructing the space area and for efficient mitigation of the seismic risk. Both geotechnical and geophysical investigation of the subsurface is required to describe the subsurface complexity. In mountainous regions, geophysical methods are gaining popularity as areas can be studied without disturbing the ground surface, and also these methods are time and cost-effective. The MASW method is used to calculate the Vs30. Vs30 is the average shear wave velocity for the top 30m of soil. Shear wave velocity is considered the best stiffness indicator, and the average of shear wave velocity up to 30 m is used in National Earthquake Hazards Reduction Program (NEHRP) provisions (BSSC,1994) and Uniform Building Code (UBC), 1997 classification. Parameters obtained through geotechnical investigation have been integrated with findings obtained through the subsurface geophysical survey. Joint interpretation has been used to establish inter-relationships among mineral constituents, various textural parameters, and unconfined compressive strength (UCS) with shear wave velocity. It is found that results obtained through the MASW method fitted well with the laboratory test. In both conditions, mineral constituents and textural parameters (grain size, grain shape, grain orientation, and degree of interlocking) control the petrophysical and mechanical properties of rocks and the behavior of shear wave velocity.

Keywords: MASW, mechanical, petrophysical, site characterization

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Authors: Lali Shanshiashvili, Marika Chikviladze, Nino Mamulashvili, Maia Sepashvili, Nana Narmania, David Mikeladze

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Purpose: During demyelinating inflammatory diseases and after the damage of the myelin sheet, myelin-derived proteins, including myelin basic protein (MBP), are secreted into the extracellular space. MBP shows extensive post-translational modifications, including the deimination of arginine residues. Deiminated MBP is structurally less ordered, susceptible to proteolytic attack, and more immunogenic than the unmodified one. It is hypothesized that MBP could change the inflammatory response in astrocytes. Methods: MBP was isolated and purified from bovine brain white matter. Primary astrocyte cultures were prepared from whole brains of 2-day-old Wistar rats. For evaluation of glutamate uptake/release in astrocytes following treatment of cells with MBP charge isomers, Glutamate Assay Kit was used. The expression of EAAT-2 (excitatory amino acid transporters), peroxisome proliferator-activated receptor gamma (PPAR- γ), inhibitor of nuclear factor kappa B (IkB), and high mobility group protein B1 (HMGB1) in astrocytes were assayed by Western Blot analysis. Results: This study investigated the action of deiminated isomer (C8) on the cultured primary astrocytes and compared its effects with the effects of unmodified C1 isomers. The study found that C8 and C1 MBP differently act on the uptake and release of glutamate in astrocytes: nonmodified C1 MBP increases the uptake of glutamate and does not change the release, whereas C8 decreases the release of glutamate but does not alter the uptake. Nevertheless, both isomers increased the expression of PPAR-γ and EAAT2 in the same intensity. However, immunostaining and Western Blots of cell lysates showed a decrease of IkB and increased expression of HMGB1 after the treatment of astrocytes by C8. Moreover, in the presence of C8, astrocytes release more nitric oxide than unmodified C1 isomers. Conclusion: These data suggest that the deiminated isomer of MBP evokes an inflammatory response and enhances the ability of astrocytes to release proinflammatory mediators through activation of NF-kB after the breakdown of myelin sheets. Acknowledgment: This research was supported by the SRNSF Georgia RF17_534 grant.

Keywords: myelin basic protein, glutamate, deimination, astrocytes, inflammation

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Authors: Aastha Paliwal, H. N. Chanakya, S. Dasappa

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Lignocellulose, as an alternate feedstock for biogas production, has been an active area of research. However, lignocellulose poses a lot of operational difficulties- widespread variation in the structural organization of lignocellulosic matrix, amenability to degradation, low bulk density, to name a few. Amongst these, the low bulk density of the lignocellulosic feedstock is crucial to the process operation and optimization. Low bulk densities render the feedstock floating in conventional liquid/wet digesters. Low bulk densities also restrict the maximum achievable organic loading rate in the reactor, decreasing the power density of the reactor. However, during digestion, lignocellulose undergoes very high compaction (up to 26 times feeding density). This first reduces the achievable OLR (because of low feeding density) and compaction during digestion, then renders the reactor space underutilized and also imposes significant mass transfer limitations. The objective of this paper was to understand the effects of compacting lignocellulose on mass transfer and the influence of loss of different components on the bulk density and hence structural integrity of the digesting lignocellulosic feedstock. 10 different lignocellulosic feedstocks (monocots and dicots) were digested anaerobically in a fed-batch, leach bed reactor -solid-state stratified bed reactor (SSBR). Percolation rates of the recycled bio-digester liquid (BDL) were also measured during the reactor run period to understand the implication of compaction on mass transfer. After 95 ds, in a destructive sampling, lignocellulosic feedstocks digested at different SRT were investigated to quantitate the weekly changes in bulk density and lignocellulosic composition. Further, percolation rate data was also compared to bulk density data. Results from the study indicate loss of hemicellulose (r²=0.76), hot water extractives (r²=0.68), and oxalate extractives (r²=0.64) had dominant influence on changing the structural integrity of the studied lignocellulose during anaerobic digestion. Further, feeding bulk density of the lignocellulose can be maintained between 300-400kg/m³ to achieve higher OLR, and bulk density of 440-500kg/m³ incurs significant mass transfer limitation for high compacting beds of dicots.

Keywords: anaerobic digestion, bulk density, feed compaction, lignocellulose, lignocellulosic matrix, cellulose, hemicellulose, lignin, extractives, mass transfer

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Authors: Germans Natuhwera, Peter Ellis, Acuda Wilson, Anne Merriman, Martha Rabwoni

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Objective: The aim of the study was to diagnose the socio-economic burden and impact of a diagnosis of cervical cancer (CC) in rural women in the context of low-resourced country Uganda, using a phenomenological enquiry. Methods: This was a multi-site phenomenological inquiry, conducted at three hospice settings; Mobile Hospice Mbarara in southwestern, Little Hospice Hoima in Western, and Hospice Africa Uganda Kampala in central Uganda. A purposive sample of women with a histologically confirmed diagnosis of CC was recruited. Data was collected using open-ended audio-recorded interviews conducted in the native languages of participants. Interviews were transcribed verbatim in English, and Braun and Clarke’s (2019) framework of thematic analysis was used. Results: 13 women with a mean age of 49.2 and age range 29-71 participated in the study. All participants were of low socioeconomic status. The majority (84.6%) had advanced disease at diagnosis. A fuller reading of transcripts produced four major themes clustered under; (1) socioeconomic characteristics of women, (2) impact of CC on women’s relationships, (3) disrupted and impaired activities of daily living (ADLs), and (4) economic disruptions. Conclusions: A diagnosis of CC introduces significant socio-economic disruptions in a woman’s and her family’s life. CC causes disability, impairs the woman and her family’s productivity hence exacerbating levels of poverty in the home. High and expensive out-of-pocket expenditure on treatment, investigations, and transport costs further compound the socio-economic burden. Decentralizing cancer care services to regional centers, scaling up screening services, subsidizing costs of cancer care services, or making cervical cancer care treatment free of charge, strengthening monitoring mechanisms in public facilities to curb the vice of healthcare workers soliciting bribes from patients, increased mass awareness campaigns about cancer, training more healthcare professionals in cancer investigation and management, and palliative care, and introducing an introductory course on gynecologic cancers into all health training institutions are recommended.

Keywords: activities of daily living, cervical cancer, out-of-pocket, expenditure, phenomenology, socioeconomic

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Authors: J. Satya Eswari, J. Sekhar Babub, Meena Murmu, Govardhan Bhat

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Electrical Discharge Machining (EDM) is an unconventional manufacturing process based on removal of material from a part by means of a series of repeated electrical sparks created by electric pulse generators at short intervals between a electrode tool and the part to be machined emmersed in dielectric fluid. In this paper, a study will be performed on the influence of the factors of peak current, pulse on time, interval time and power supply voltage. The output responses measured were material removal rate (MRR) and surface roughness. Finally, the parameters were optimized for maximum MRR with the desired surface roughness. RSM involves establishing mathematical relations between the design variables and the resulting responses and optimizing the process conditions. RSM is not free from problems when it is applied to multi-factor and multi-response situations. Design of experiments (DOE) technique to select the optimum machining conditions for machining AISI 4140 using EDM. The purpose of this paper is to determine the optimal factors of the electro-discharge machining (EDM) process investigate feasibility of design of experiment techniques. The work pieces used were rectangular plates of AISI 4140 grade steel alloy. The study of optimized settings of key machining factors like pulse on time, gap voltage, flushing pressure, input current and duty cycle on the material removal, surface roughness is been carried out using central composite design. The objective is to maximize the Material removal rate (MRR). Central composite design data is used to develop second order polynomial models with interaction terms. The insignificant coefficients’ are eliminated with these models by using student t test and F test for the goodness of fit. CCD is first used to establish the determine the optimal factors of the electro-discharge machining (EDM) for maximizing the MRR. The responses are further treated through a objective function to establish the same set of key machining factors to satisfy the optimization problem of the electro-discharge machining (EDM) process. The results demonstrate the better performance of CCD data based RSM for optimizing the electro-discharge machining (EDM) process.

Keywords: electric discharge machining (EDM), modeling, optimization, CCRD

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Authors: Laura Amato, Paolo Mulatti, Fabrizio Montarsi, Matteo Mazzucato, Laura Gagliazzo, Michele Brichese, Manlio Palei, Gioia Capelli, Lebana Bonfanti

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West Nile virus (WNV) re-emerged in north-eastern Italy in 2008, after ten years from its first appearance in Tuscany. In 2009, a national surveillance programme was implemented, and re-modulated in north-eastern Italy in 2011. Hereby, we present the results of surveillance activities in 2008-2016 in the north-eastern Italian regions, with inferences on WNV epidemiological trend in the area. The re-modulated surveillance programmes aimed at early detecting WNV seasonal reactivation by searching IgM antibodies in horses. In 2013, the surveillance plans were further modified including a risk-based approach. Spatial analysis techniques, including Bernoulli space-time scan-statistics, were applied to the results of 2010–2012 surveillance on mosquitoes, equines, and humans to identify areas where WNV reactivation was more likely to occur. From 2008 to 2016, residential horses tested positive for anti-WNV antibodies on a yearly basis (503 cases), also in areas where WNV circulation was not detected in mosquito populations. Surveillance activities detected 26 syndromic cases in horses, 102 infected mosquito pools and WNV in 18 dead wild birds. Human cases were also recurrently detected in the study area during the surveillance period (68 cases of West Nile neuroinvasive disease). The recurrent identification of WNV in animals, mosquitoes, and humans indicates the virus has likely become endemic in the area. In 2016, findings of WNV positives in horses or mosquitoes were included as triggers for enhancing screening activities in humans. The evolution of the epidemiological situation prompts for continuous and accurate surveillance measures. The results of the 2013-2016 surveillance indicate that the risk-based approach was effective in early detecting seasonal reactivation of WNV, key factor of the integrated surveillance strategy in endemic areas.

Keywords: arboviruses, horses, Italy, surveillance, west nile virus, zoonoses

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Authors: Soo Min Kim, Soo-Won Chae, Soung-Yon Kim, Haea Lee, Ju Yong Kang, Juneyong Lee, Seung-Ho Han

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Reverse total shoulder arthroplasty (RTSA) has become an effective treatment option for cuff tear arthropathy and massive, irreparable rotator cuff tears and indications for its use are expanding. Numerous methods for optimal fixation of the glenoid component have been suggested, such as inferior overhang, inferior tilt, to maximize initial fixation and prevent glenoid component loosening. The inferior tilt fixation of a glenoid component has been suggested, which is expected to decrease scapular notching and to improve the stability of a glenoid component fixation in reverse total shoulder arthroplasty. Inferior tilt fixation of the glenoid component has been suggested, which can improve stability and, because it provides the most uniform compressive forces and imparts the least amount of tensile forces and micromotion, reduce the likelihood of mechanical failure. Another study reported that glenoid component inferior tilt improved impingement-free range of motion as well as minimized the scapular notching. Several authors have shown that inferior tilt of a glenoid component reduces scapular notching. However, controversy still exists regarding its importance in the literature. In this study the influence of inferior tilt fixation on the primary stability of a glenoid component has been investigated. Finite element models were constructed from cadaveric scapulae and glenoid components were implanted with neutral and 10° inferior tilts. Most previous biomechanical studies regarding the effect of glenoid component inferior tilt used a solid rigid polyurethane foam or sawbones block, not cadaveric scapulae, to evaluate the stability of the RTSA. Relative micromotions at the bone-glenoid component interface, and the distribution of bone stresses under the glenoid component and around the screws were analyzed and compared between neutral and 10° inferior tilt groups. Contact area between bone and screws and cut surface area of the cancellous bone exposed after reaming of the glenoid have also been investigated because of the fact that cancellous and cortical bone thickness vary depending on the resection level of the inferior glenoid bone. The greater relative micromotion of the bone-glenoid component interface occurred in the 10° inferior tilt group than in the neutral tilt group, especially at the inferior area of the bone-glenoid component interface. Bone stresses under the glenoid component and around the screws were also higher in the 10° inferior tilt group than in the neutral tilt group, especially at the inferior third of the glenoid bone surface under the glenoid component and inferior scapula. Thus inferior tilt fixation of the glenoid component may adversely affect the primary stability and longevity of the reverse total shoulder arthroplasty.

Keywords: finite element analysis, glenoid component, inferior tilt, reverse total shoulder arthroplasty

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Authors: Yasir Bashawri, Vincent N. Chigor James McDonald, Merfyn Williams, Davey Jones, A. Prysor Williams

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Resistance to antibiotics has become a threat to public health. As a result of their misuse and overuse, bacteria have become resistant to many common antibiotics. Βeta lactam (β-lactam) antibiotics are one of the most significant classes of antimicrobials in providing therapeutic benefits for the treatment of bacterial infections in both human and veterinary medicine, for approximately 60% of all antibiotics are used. In particular, some Enterobacteriaceae produce Extend Spectrum Beta Lactamases (ESBLs) that enable them to some break down multi-groups of antibiotics. CTX-M enzymes have rapidly become the most important ESBLs, with increases in mainly CTX-M 15 in many countries during the last decade. Global travel by intercontinental medical ‘tourists’, migrant employees and overseas students could theoretically be a risk factor for spreading antibiotic resistance genes in different parts of the world. Bangor city, North Wales, is subject to sudden demographic changes due to a large proportion (>25%) of the population being students, most of which arrive over a space of days. This makes it a suitable location to study the impacts of large demographic change on the presence of ESBLs. The aim of this study is to monitor the presence of ESBLs in Escherichia coli and faecal coliform bacteria isolated from Bangor wastewater treatment plant, before, during and after the arrival week of students to Bangor University. Over a five-week period, water samples were collected twice a week, from the influent, primary sedimentation tank, aeration tank and the final effluent. Isolation and counts for Escherichia coli and other faecal coliforms were done on selective agar (primary UTI agar). ESBL presence will be confirmed by phenotypic and genotypic methods. Sampling at all points of the tertiary treatment stages will indicate the effectiveness of wastewater treatment in reducing the spread of ESBLs genes. The study will yield valuable information to help tackle a problem which many regard to be the one of the biggest threats to modern-day society.

Keywords: extended spectrum β-lactamase, enterobacteriaceae, international travel, wastewater treatment plant

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Authors: M. El-haj, Z. Olama, H. Holail

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Single cell oils (SCOs) accumulated by oleaginous fungi have emerged as a potential alternative feedstock for biodiesel production. Five fungal strains were isolated from the Lebanese environment namely Fusarium oxysporum, Mucor hiemalis, Penicillium citrinum, Aspergillus tamari, and Aspergillus niger that have been selected among 39 oleaginous strains for their potential ability to accumulate lipids (lipid content was more than 40% on dry weight basis). Wide variations were recorded in the environmental factors that lead to maximum lipid production by fungi under test and were cultivated under submerged fermentation on medium containing glucose as a carbon source. The maximum lipid production was attained within 6-8 days, at pH range 6-7, 24 to 48 hours age of seed culture, 4 to 6.107 spores/ml inoculum level and 100 ml culture volume. Eleven culture conditions were examined for their significance on lipid production using Plackett-Burman factorial design. Reducing sugars and nitrogen source were the most significant factors affecting lipid production process. Maximum lipid yield was noticed with 15.62, 14.48, 12.75, 13.68 and 20.41g/l for Fusarium oxysporum, Mucor hiemalis, Penicillium citrinum, Aspergillus tamari, and Aspergillus niger respectively. A verification experiment was carried out to examine model validation and revealed more than 94% validity. The profile of extracted lipids from each fungal isolate was studied using thin layer chromatography (TLC) indicating the presence of monoacylglycerols, diaacylglycerols, free fatty acids, triacylglycerols and sterol esters. The fatty acids profiles were also determined by gas-chromatography coupled with flame ionization detector (GC-FID). Data revealed the presence of significant amount of oleic acid (29-36%), palmitic acid (18-24%), linoleic acid (26.8-35%), and low amount of other fatty acids in the extracted fungal oils which indicate that the fatty acid profiles were quite similar to that of conventional vegetable oil. The cost of lipid production could be further reduced with acid-pretreated lignocellulotic corncob waste, whey and date molasses to be utilized as the raw material for the oleaginous fungi. The results showed that the microbial lipid from the studied fungi was a potential alternative resource for biodiesel production.

Keywords: agro-industrial waste products, biodiesel, fatty acid, single cell oil, Lebanese environment, oleaginous fungi

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Authors: Adline Nkwam-Uwaoma, Mishack Ndukwu

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Traditionally, child rearing in Nigeria closely reflects the ‘spare the rod and spoil the child’ maxim and as such spanking, flogging, slapping, beating and even starving a child as a form of punishment for wrongdoing and as a method of behaviour modification are common. These are not necessarily considered as maltreatment or abuse of the child. Despite the adoption and implementation of the child rights act in Nigeria, violence against children seems to be on a steady increase. Stories of sexual molestation, rape, child labour, infliction of physical injuries and use of children for rituals by parents, guardians or other members of the society abound. Violence against children is considered as those acts by other persons especially adults that undermine and threaten the healthy life and existence of children or those that violet their rights as humans. In Nigeria newspapers are a major source of News, second only to radio and television in coverage, currency and content. National dailies are newspapers with daily publications and national spread or coverage. This study analysed the frequency, length, prominence level, direction and sources of information reported on violence against children in the selected national daily newspapers. It then provided information on the role of the newspapers in Nigeria in the fight against child violence and public awareness of the impact of violence against children on the development of the nation and the attempts to curtail such violence. The composite week sampling technique in which the four weeks of the month are reduced to one and a sample is randomly selected from each day of the week was used. As such 168 editions of Daily Sun and Punch newspapers published from January to December of 2016 were selected. Data were collected using code sheet and analyzed via content analysis. The result showed that the frequency of the newspapers’ reportage of violence against children in Nigeria was low. Again, it was found that the length or space given to reports on violence against children was inadequate, the direction of the few reports on violence against children was in favour of the course or fight against child violence, and these newspapers gave no prominence to reports on violence against children. Finally, it was found that a major source of News about violence against children was through journalism; government and individual sources provided only minimal information.

Keywords: children, newspapers' reportage, Nigeria, violence

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Authors: Dong-An Wang

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All kinds of microspheres have been extensively employed as carriers for drug, gene and therapeutic cell delivery. Most therapeutic cell delivery microspheres rely on a two-step methodology: fabrication of microspheres and subsequent seeding of cells onto them. In this study, we have developed a novel one-step cell encapsulation technique using a convenient and instant water-in-oil single emulsion approach to form cell-encapsulated gelatin microspheres. This technology is adopted for hyaline cartilage tissue engineering, in which autologous chondrocytes are used as therapeutic cells. Cell viability was maintained throughout and after the microsphere formation (75-100 µm diameters) process that avoids involvement of any covalent bonding reactions or exposure to any further chemicals. Further encapsulation of cell-laden microspheres in alginate gels were performed under 4°C via a prompt process. Upon the formation of alginate constructs, they were immediately relocated into CO2 incubator where the temperature was maintained at 37°C; under this temperature, the cell-laden gelatin microspheres dissolved within hours to yield similarly sized cavities and the chondrocytes were therefore suspended within the cavities inside the alginate gel bulk. Hence, the gelatin cell-laden microspheres served two roles: as cell delivery vehicles which can be removable through temperature curing, and as porogens within an alginate hydrogel construct to provide living space for cell growth and tissue development as well as better permeability for mutual diffusions. These cell-laden microspheres, namely “temperature-cured dissolvable gelatin microsphere based cell carriers” (tDGMCs), were further encapsulated in a chondrocyte-laden alginate scaffold system and analyzed by WST-1, gene expression analyses, biochemical assays, histology and immunochemistry stains. The positive results consistently demonstrated the promise of tDGMC technology in delivering these non-anchorage dependent cells (chondrocytes). It can be further conveniently translated into delivery of other non-anchorage dependent cell species, including stem cells, progenitors or iPS cells, for regeneration of tissues in internal organs, such as engineered hepatogenesis or pancreatic regeneration.

Keywords: biomaterials, tissue engineering, microsphere, hydrogel, porogen, anchorage dependence

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Authors: L. N. P. Wedikandage, Mohamed Razmi Zahir

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Technology is a global imperative because of its contributions to human existence and because it has improved global socioeconomic relations. As a result, the mobile phone has become the most important mode of communication today. Smartphones, Internet-enabled devices with built-in computer software and applications, are one of the most significant inventions of the twenty-first century. Technology is advantageous to many people, especially those involved in education. It is an important learning tool for today's schoolchildren. It enables students to access online learning platforms and course resources and interact digitally. Senior secondary students, in particular, have some of the most expensive and sophisticated mobile phones, tablets, and iPads capable of connecting to the internet and various social media platforms, other websites, and so on. At present, the use of mobile phones' potential for effective teaching and learning is growing. This is due to the benefits of mobile learning, including the ability to share knowledge without any limits in space or Time and the capacity to facilitate the development of critical thinking, participatory learning, problem-solving, and the development of lifelong communication skills. However, it is yet unclear how mobile devices may affect education and how they may affect opportunities for learning. As a result, the purpose of this research was to ascertain the relationship between mobile phone usage and the academic Performance of secondary-level students at an international school in Sri Lanka. The study's sample consisted of 523 secondary-level students from an international school, ranging from Form 1 to Upper 6. For the study, a survey research design and questionnaires were used. Google Forms was used to create the students' survey. There were three hypotheses tested to find out the relationship between mobile phone usage and academic preference. The findings show that there is a positive relationship between mobile phone usage and academic performance among secondary school students (the number of students obtaining simple passes is significantly higher when mobile phones are being used for more than 7 hours), no relationship between mobile phone usage and academic performance among secondary school students of different parents' occupations, and a relationship between the frequency of mobile phone usage and academic performance among secondary school students.

Keywords: mobile phone, academic performance, secondary level, international schools

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Authors: B. Vinod, L. Jsudev

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Natural fibers as reinforcement in polymer matrix material is gaining lot of attention in recent years, as they are light in weight, less in cost, and ecologically advanced surrogate material to glass and carbon fibers in composites. Natural fibers like jute, sisal, coir, hemp, banana etc. have attracted substantial importance as a potential structural material because of its attractive features along with its good mechanical properties. Cryogenic applications of natural fiber reinforced polymer composites like cryogenic wind tunnels, cryogenic transport vessels, support structures in space shuttles and rockets are gaining importance. In these unique cryogenic applications, the requirements of polymer composites are extremely severe and complicated. These materials need to possess good mechanical and physical properties at cryogenic temperatures such as liquid helium (4.2 K), liquid hydrogen (20 K), liquid nitrogen (77 K), and liquid oxygen (90 K) temperatures, etc., to meet the high requirements by the cryogenic engineering applications. The objective of this work is to investigate the mechanical behavior of hybrid hemp/jute fibers reinforced epoxy composite material at liquid nitrogen temperature. Hemp and Jute fibers are used as reinforcement material as they have high specific strength, stiffness and good adhering property and has the potential to replace the synthetic fibers. Hybrid hemp/jute fibers reinforced polymer composite is prepared by hand lay-up method and test specimens are cut according to ASTM standards. These test specimens are dipped in liquid nitrogen for different time durations. The tensile properties, flexural properties and impact strength of the specimen are tested immediately after the specimens are removed from liquid nitrogen container. The experimental results indicate that the cryogenic treatment of the polymer composite has a significant effect on the mechanical properties of this material. The tensile properties and flexural properties of the hybrid hemp/jute fibers epoxy composite at liquid nitrogen temperature is higher than at room temperature. The impact strength of the material decreased after subjecting it to liquid nitrogen temperature.

Keywords: liquid nitrogen temperature, polymer composite, tensile properties, flexural properties

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Authors: Bahor Bahriddinovna Turaeva

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The article provides a structural analysis of the titles of the famous Kyrgyz writer Chingiz Aitmatov’s creative works “The Day Lasts More Than a Hundred Years”, “Doomsday”. The author’s creative purpose in naming the work of art, the role of the elements of the plot, and the composition of the novels in revealing the essence of the title are explained. The criteria that are important in naming the author’s works in different genres are classified, and the titles that mean artistic time and artistic space are studied separately. Chronotope is being concerned as the literary-aesthetic category in world literary studies, expressing the scope of the universe interpretation, the author’s outlook and imagination regarding the world foundation, defining personages, and the composition means of expressing the sequence and duration of the events. A creative comprehension of the chronotope as a means of arranging the work composition, structure and constructing an epic field of the text demands a special approach to understanding the aesthetic character of the work. Since the chronotope includes all the elements of a fictional work, it is impossible to present the plot, composition, conflict, system of characters, feelings, and mood of the characters without the description of the chronotope. In the following development of the scientific-theoretical thought in the world, the chronotope is accepted to be one of the poetic means to demonstrate reality as well as to be a literary process that is basic for the expression of reality in the compositional construction and illustration of the plot relying on the writer’s intention and the ideological conception of the literary work. Literary time enables one to cognate the literary world picture created by the author in terms of the descriptive subject and object of the work. Therefore, one of the topical tasks of modern Uzbek literary studies is to describe historical evidence, event, the life of outstanding people, the chronology of the near past based on the literary time; on the example of the creative works of a certain period, creators or an individual writer are analyzed in separate or comparative-typological aspect.

Keywords: novel, title, chronotope, motive, epigraph, analepsis, structural analysis, plot line, composition

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Authors: Eman Nagi Gowid Selim

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Nowadays, the relevance of places to people has been questioned from different perspectives. This is attributed to the fact that many international concrete blocks were used to create multi-use public spaces in neighborhoods based on the techniques of mass-productions concepts that became one of the most effective ways in building construction, replacing the local and traditional built environment. During the last decades, the world has become increasingly globalized and citizen more mobilized, and thus, ignoring the social and environmental dimensions of the local identity. The main enquiries of the research are “How did building technologies affect urban settlement’s identity?” and “What are the impacts of technologies and globalization on local identities in urban spaces? “From this perspective, the research presents firstly, a historical review that shows how old civilizations enhance their local identities using the newly discovered building materials in each era in different urban settlement and fabrics without losing the identity. The second part of the research highlights the different approaches of building technologies and urban design to present a clear understanding of ways of applying and merging between different methodologies to achieve the most efficient urban space design. The third part aims at analyzing some international and national case studies where the form and structure of particular spaces are vital to identifying the morphological elements of urban settlements and the links existing between them. In addition, it determines how the building materials are used to enrich the vocabulary of the local identity. This part ends with the deduction of the guidelines for the integration of the environmental and social dimensions within the building technologies` approaches to enhance the sustainability of local identities and thus, ending up with redefining "Urban Identity" to guide future research in such cultural areas. Finally, the research uses the comparative methodology for applying the deduced guidelines on a national case study namely “Othman`s Towers” in corniche El Maadi, and then ends up by some results in the form of strategies for future researcher, that identifies how to ensure local identity in urban settlements using new building materials and technologies to achieve social and environmental comfort within the cultural areas.

Keywords: building technologies, cultural context, environmental approach, participatory design, social dimension, urban spaces

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Authors: Giannis Arnaoutis, Dimitra Efthymiopoulou, Maria-Foivi Nikolopoulou, Yannis Manios

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AIM: Nitrate-containing supplements have been used extensively as ergogenic in many sports. However, extract fractions from plant-based nutritional sources high in nitrate and their effect on athletic performance, has not been systematically investigated. The purpose of the present study was to examine the possible effect of acute consumption of a “smart mixture” from beetroot and rocket on exercise capacity. MATERIAL & METHODS: 12 healthy, nonsmoking, recreationally active, males (age: 25±4 years, % fat: 15.5±5.7, Fat Free Mass: 65.8±5.6 kg, VO2 max: 45.46.1 mL . kg -1 . min -1) participated in a double-blind, placebo-controlled trial study, in a randomized and counterbalanced order. Eligibility criteria for participation in this study included normal physical examination, and absence of any metabolic, cardiovascular, or renal disease. All participants completed a time to exhaustion cycling test at 75% of their maximum power output, twice. The subjects consumed either capsules containing 360 mg of nitrate in total or placebo capsules, in the morning, under fasted state. After 3h of passive recovery the performance test followed. Blood samples were collected upon arrival of the participants and 3 hours after the consumption of the corresponding capsules. Time until exhaustion, pre- and post-test lactate concentrations, and rate of perceived exertion for the same time points were assessed. RESULTS: Paired-sample t-test analysis found a significant difference in time to exhaustion between the trial with the nitrate consumption versus placebo [16.1±3.0 Vs 13.5±2.6 min, p=0.04] respectively. No significant differences were observed for the concentrations of lactic acid as well as for the values in the Borg scale between the two trials (p>0.05). CONCLUSIONS: Based on the results of the present study, it appears that a nutritional supplement derived from vegetable extracts rich in nitrate, improves athletic performance in recreationally active young males. However, the precise mechanism is not clear and future studies are needed. Acknowledgment: This research has been co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code:T2EDK-00843).

Keywords: sports performance, ergogenic supplements, nitrate, extract fractions

Procedia PDF Downloads 49

Authors: Prashantkumar Waghe, N. Prakash, N. D. Prasada, L. V. Lokesh, M. Vijay Kumar, Vinay Tikare

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Arsenic is a naturally occurring metalloid with potent toxic effects. It is ubiquitous in the environment and released from both natural and anthropogenic sources. It has the potential to cause various health hazards in exposed populations. Arsenic exposure through drinking water is considered as one of the most serious global environmental threats including Southeast Asia. The aim of present study was to evaluate the modulatory role of subacute exposure to sodium (meta) arsenite on the antinociceptive, anti-inflammatory and antipyretic responses mediated by meloxicam in rats. Rats were exposed to arsenic as sodium arsenite through drinking water for 28 days. A single dose of meloxicam (2 mg/kg b. wt.) was administered by oral gavage on the 29th day. The exact time of meloxicam administration depended on the type of test. Rats were divided randomly into 5 groups (n=6). Group I served as normal control and received arsenic free drinking water, while rats in group II were maintained similar to Group I but received meloxicam on 29th day. Groups III, IV and V were pre-exposed to arsenic through drinking water at 0.5, 5.0 and 50 ppm, respectively, for 28 days and was administered meloxicam next day and; pain and inflammation carried out by using formalin-induced nociception and carrageenan-induced inflammatory model(s), respectively by using standard protocol. For assessment of antipyretic effects, one more additional group (Group VI) was taken and given LPS @ 1.8 mg/kg b. wt. for induction of pyrexia (LPS control). Higher dose of arsenic inhibited the meloxicam mediated antinociceptive, anti-inflammatory and antipyretic responses. Further, meloxicam inhibited the arsenic induced level of tumor necrosis factor-α, inetrleukin-1β, interleukin -6 and COX2 mediated prostaglandin E2 in hind paw muscle. These results suggest a functional antagonism of meloxicam by arsenic. This may relate to arsenic mediated local release of tumor necrosis factor-α, inetrleukin-1β, interleukin -6 releases COX2 mediated prostaglandin E2. Based on the experimental study, it is concluded that sub-acute exposure to arsenic through drinking water aggravate pyrexia, inflammation and pain at environment relevant concentration and decrease the therapeutic efficacy of meloxicam at higher level of arsenite exposure. Thus, the observation made has clinical relevance in situations where animals are exposed to arsenite epidemic geographical locations.

Keywords: arsenic, analgesic activity, meloxicam, Wistar rats

Procedia PDF Downloads 166

Authors: Haniyeh Sameie

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In the process of globalization, geographical boundaries gradually lose their importance, and ethnic, local, and regional cultures are integrated with each other and even marginalized. Globalization has many manifestations and aspects, including economic, political, social, etc., but this paper has focused on the cultural aspect of globalization. From this point of view, one of the important issues that have always been raised is the assimilation of diverse and plural cultures, which are gradually disappearing and destroyed in the onslaught of global culture and are dissolved in global culture. In the postmodern paradigm, the tools of the globalized world can be used to preserve and strengthen cultural diversity. For example, the Internet, as a globalization tool, can play an important role in preserving and recognizing local cultures. In today's world, the world nations and ethnic groups are trying to revive their specific and native cultures in different ways in opposition to the rising cultural assimilation and challenge the globalization of culture. One of the manifestations of these actions is addressing the issue of tourism and, specifically, eco-tourism, which is being developed in Iran as well as in other parts of the world, relying on the powerful tool of globalization, the Internet. Considering the significant growth of the ecotourism industry in Iran in recent years, this paper focuses on the role of the Internet in the development of ecotourism in Iran as one of the manifestations of tourism in recent decades and how to preserve and survive diverse local cultures and strengthen local communities against global culture through it. One of the major challenges in the development of communication technology in Iran in the last decade has been the debate over the necessity or non-necessity of access to high-speed Internet in the villages of Iran. Some believe that accessing the broadband internet in the villages may lead to the disappearance of local cultures and can facilitate the spread of western culture among villagers. On the other hand, the speed of expansion of ecotourism in Iran in the last ten years is owed to the development of the Internet in villages. In this regard, we pay attention to the dual role of the Internet in cultural assimilation and, at the same time, the platform that the online space has created for the growth and development of ecotourism accommodations as a source of stable income for local communities, focusing on the Iranian experience in the recent decade.

Keywords: tourism, globalization, internet, ecotourism in Iran, cultural assimilation

Procedia PDF Downloads 58

Authors: M. V. Shivaani, P. K. Jain, Surendra S. Yadav

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Public Sector Undertakings (PSUs), being government-owned organizations have commitments for the economic and social wellbeing of the society; this commitment needs to be reflected in their risk-taking, decision-making and governance structures. Therefore, the primary objective of the study is to suggest measures that may lead to improvement in performance of PSUs. To achieve this objective two normative frameworks (one relating to risk levels and other relating to governance structure) are being put forth. The risk index is based on nine risks, such as, solvency risk, liquidity risk, accounting risk, etc. and each of the risks have been scored on a scale of 1 to 5. The governance index is based on eleven variables, such as, board independence, diversity, risk management committee, etc. Each of them are scored on a scale of 1 to five. The sample consists of 39 PSUs that featured in Nifty 500 index and, the study covers a 10 year period from April 1, 2005 to March, 31, 2015. Return on assets (ROA) and return on equity (ROE) have been used as proxies of firm performance. The control variables used in the model include, age of firm, growth rate of firm and size of firm. A dummy variable has also been used to factor in the effects of recession. Given the panel nature of data and possibility of endogeneity, dynamic panel data- generalized method of moments (Diff-GMM) regression has been used. It is worth noting that the corporate governance index is positively related to both ROA and ROE, indicating that with the improvement in governance structure, PSUs tend to perform better. Considering the components of CGI, it may be suggested that (i). PSUs ensure adequate representation of women on Board, (ii). appoint a Chief Risk Officer, and (iii). constitute a risk management committee. The results also indicate that there is a negative association between risk index and returns. These results not only validate the framework used to develop the risk index but also provide a yardstick to PSUs benchmark their risk-taking if they want to maximize their ROA and ROE. While constructing the CGI, certain non-compliances were observed, even in terms of mandatory requirements, such as, proportion of independent directors. Such infringements call for stringent penal provisions and better monitoring of PSUs. Further, if the Securities and Exchange Board of India (SEBI) and Ministry of Corporate Affairs (MCA) bring about such reforms in the PSUs and make mandatory the adherence to the normative frameworks put forth in the study, PSUs may have more effective and efficient decision-making, lower risks and hassle free management; all these ultimately leading to better ROA and ROE.

Keywords: PSU, risk governance, diff-GMM, firm performance, the risk index

Procedia PDF Downloads 145

Authors: Murad A. Channa, Mehdi Khiadani. Yasir Al-Abdeli

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Considering the severity of water scarcity around the world and its widening at an alarming rate, practical improvements in desalination techniques need to be engineered at the earliest. Atomization is the major aspect of flashing phenomena, yet it has been paid less attention to until now. There is a need to test efficient ways of atomization for the flashing process. Flash evaporation together with reverse osmosis is also a commercially matured desalination technique commonly famous as Multi-stage Flash (MSF). Even though reverse osmosis is massively practical, it is not economical or sustainable compared to flash evaporation. However, flashing evaporation has its drawbacks as well such as lower efficiency of water production per higher consumption of power and time. Flash evaporation is simply the instant boiling of a subcooled liquid which is introduced as droplets in a well-maintained negative environment. This negative pressure inside the vacuum increases the temperature of the liquid droplets far above their boiling point, which results in the release of latent heat, and the liquid droplets turn into vapor which is collected to be condensed back into an impurity-free liquid in a condenser. Atomization is the main difference between pool and spray flash evaporation. Atomization is the heart of the flash evaporation process as it increases the evaporating surface area per drop atomized. Atomization can be categorized into many levels depending on its drop size, which again becomes crucial for increasing the droplet density (drop count) per given flow rate. This review comprehensively summarizes the selective results relating to the methods of atomization and their effectiveness on the evaporation rate from earlier works to date. In addition, the reviewers propose using centrifugal atomization for the flashing application, which brings several advantages viz ultra-fine droplets, uniform droplet density, and the swirling geometry of the spray with kinetically more energetic sprays during their flight. Finally, several challenges of using rotary bell atomizer (RBA) and RBA Sprays inside the chamber have been identified which will be explored in detail. A schematic of rotary bell atomizer (RBA) integration with the chamber has been designed. This powerful centrifugal atomization has the potential to increase potable water production in commercial multi-stage flash evaporators, where it would be preferably advantageous.

Keywords: atomization, desalination, flash evaporation, rotary bell atomizer

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Authors: S. Behnia, S. Fathizadeh, A. Akhshani

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In the recent decades, DNA has increasingly interested in the potential technological applications that not directly related to the coding for functional proteins that is the expressed in form of genetic information. One of the most interesting applications of DNA is related to the construction of nanostructures of high complexity, design of functional nanostructures in nanoelectronical devices, nanosensors and nanocercuits. In this field, DNA is of fundamental interest to the development of DNA-based molecular technologies, as it possesses ideal structural and molecular recognition properties for use in self-assembling nanodevices with a definite molecular architecture. Also, the robust, one-dimensional flexible structure of DNA can be used to design electronic devices, serving as a wire, transistor switch, or rectifier depending on its electronic properties. In order to understand the mechanism of the charge transport along DNA sequences, numerous studies have been carried out. In this regard, conductivity properties of DNA molecule could be investigated in a simple, but chemically specific approach that is intimately related to the Su-Schrieffer-Heeger (SSH) model. In SSH model, the non-diagonal matrix element dependence on intersite displacements is considered. In this approach, the coupling between the charge and lattice deformation is along the helix. This model is a tight-binding linear nanoscale chain established to describe conductivity phenomena in doped polyethylene. It is based on the assumption of a classical harmonic interaction between sites, which is linearly coupled to a tight-binding Hamiltonian. In this work, the Hamiltonian and corresponding motion equations are nonlinear and have high sensitivity to initial conditions. Then, we have tried to move toward the nonlinear dynamics and phase space analysis. Nonlinear dynamics and chaos theory, regardless of any approximation, could open new horizons to understand the conductivity mechanism in DNA. For a detailed study, we have tried to study the current flowing in DNA and investigated the characteristic I-V diagram. As a result, It is shown that there are the (quasi-) ohmic areas in I-V diagram. On the other hand, the regions with a negative differential resistance (NDR) are detectable in diagram.

Keywords: DNA conductivity, Landauer resistance, negative dierential resistance, Chaos theory, mean Lyapunov exponent

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Authors: Dhruvit S. Berawala, Jann R. Ursin, Obrad Slijepcevic

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Shale gas is one of the most rapidly growing forms of natural gas. Unconventional natural gas deposits are difficult to characterize overall, but in general are often lower in resource concentration and dispersed over large areas. Moreover, gas is densely packed into the matrix through adsorption which accounts for large volume of gas reserves. Gas production from tight shale deposits are made possible by extensive and deep well fracturing which contacts large fractions of the formation. The conventional reservoir modelling and production forecasting methods, which rely on fluid-flow processes dominated by viscous forces, have proved to be very pessimistic and inaccurate. This paper presents a new approach to forecast shale gas production by detailed modeling of gas desorption, diffusion and non-linear flow mechanisms in combination with statistical representation of these processes. The representation of the model involves a cube as a porous media where free gas is present and a sphere (SiC: Sphere in Cube model) inside it where gas is adsorbed on to the kerogen or organic matter. Further, the sphere is considered consisting of many layers of adsorbed gas in an onion-like structure. With pressure decline, the gas desorbs first from the outer most layer of sphere causing decrease in its molecular concentration. The new available surface area and change in concentration triggers the diffusion of gas from kerogen. The process continues until all the gas present internally diffuses out of the kerogen, gets adsorbs onto available surface area and then desorbs into the nanopores and micro-fractures in the cube. Each SiC idealizes a gas pathway and is characterized by sphere diameter and length of the cube. The diameter allows to model gas storage, diffusion and desorption; the cube length takes into account the pathway for flow in nanopores and micro-fractures. Many of these representative but general cells of the reservoir are put together and linked to a well or hydraulic fracture. The paper quantitatively describes these processes as well as clarifies the geological conditions under which a successful shale gas production could be expected. A numerical model has been derived which is then compiled on FORTRAN to develop a simulator for the production of shale gas by considering the spheres as a source term in each of the grid blocks. By applying SiC to field data, we demonstrate that the model provides an effective way to quickly access gas production rates from shale formations. We also examine the effect of model input properties on gas production.

Keywords: adsorption, diffusion, non-linear flow, shale gas production

Procedia PDF Downloads 149

Authors: Cristina Munoz-Shuguli, Francisco Rodriguez, Julio Bruna, M. Jose Galotto, Abel Guarda

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The microbial contamination in fruits due to the presence of fungal is the most important cause of their deterioration and loss. The development of active food packaging materials with antifungal properties has been proposed as an innovative strategy in order to prevent this problem. In this way, natural compounds as the essential oils or their derivatives, also called volatile compounds (VC), can be incorporated in the food packaging materials to control the fungal growth during fruit packaging. However, if the VC is incorporated directly in the packaging material, it is released very fast due to VC high volatility. For this reason, the formation of inclusion complexes through the encapsulation of VC into beta-cyclodextrin (β-CD) and their incorporation in package materials is an alternative to maintain an antifungal atmosphere around the packaged fruits for longer times. In this context, the aim of this work was to develop inclusion complexes based in β-CD and VC (β-CD:VC) for further application in the antifungal food packaging materials development. β-CD:VC inclusion complexes were obtained with two different molar ratios 2:1 and 1:1, through co-precipitation method. The entrapment efficiency of β-CD:VC as well the release of antifungal compound from inclusion complexes exposed to different relative humidity (25, 50, and 97 %) to headspace were determined by gaseous chromatography (GC). Also, thermal and antimicrobial properties of β-CD:VC were determined through thermogravimetric analysis (TGA) and antifungal assays against Botrytis cinerea, respectively. GC results showed that β-CD:VC 2:1 had a higher entrapment efficiency than β-CD:VC 1:1, with values of 75.5 ± 3.71 % and 59.6 ± 1.51 %, respectively. It was probably because during the synthesis of β-CD:VC 1:1, there was less molecular space to the movement of VC molecules. Furthermore, the release of VC from β-CD:VC was directly related with the relative humidity. High amount of VC was released when the inclusion complexes were exposed to high humidity, possibly due to the interactions between the water molecules and the β-CD hydrophilic wall. On the other hand, a better thermal stability of VC in inclusion complexes allowed to verify its effective encapsulation into β-CD. Finally, antimicrobial assays showed that the inclusion complexes had a high antifungal activity at very low concentrations. Therefore, the results obtained in this work allow suggesting the β-CD:VC inclusion complexes as potential candidates to the development of fruit antifungal packaging materials, which activity is relative humidity dependent.

Keywords: Botrytis cinerea, fruit packaging, headspace release, volatile compounds

Procedia PDF Downloads 98

Authors: M. Weller Jones, J. Moffat, J. Taylor, J. Hartland, M. Natarajan

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Background: Uganda’s teenage pregnancy rate remains a significant problem for female and maternal health in the country. Teenage pregnancy is linked to higher rates of maternal and neonatal mortality and morbidity, including preterm labour, obstructed labour, vesicovaginal fistulae, infections, and maternal mental health morbidity. In 2015, the National Strategy to End Child Marriage and Teenage Pregnancy was launched in Uganda. Research is needed so that the interventions in this Strategy can be effectively applied at a local level. This study at Kitovu and Villa Maria Hospitals, two local community hospitals near Masaka, Uganda, aimed to measure change in the local teenage pregnancy rate over the past 5 years; and to explore the awareness and attitudes of teenagers and healthcare professionals towards 1) teenage pregnancy and, 2) the challenges female adolescents still currently face. Method: Teenage delivery rate, type of delivery, incidence of complications in labour and neonatal and maternal outcomes were collected from the labour ward admission books, at both hospitals, for a six month time period in 2011 and 2016. At Kitovu Hospital, qualitative data regarding the experience of, and attitudes towards teenage pregnancy was collected from interviews conducted with 12 maternity staff members and with eight female teenagers, aged 16-19, who were pregnant or post-partum. Results: The proportion of total births to teenage mothers fell from 14% in 2011 to 7% in 2016 (Kitovu), but it remains higher in rural locations (19%, Villa Maria). Beliefs about exacerbating factors included: poor access to contraception; misconceptions that contraception is damaging to women’s health; failing sex education in schools; and poor awareness of national campaigns to reduce teenage pregnancy. Staff felt that the best way to tackle teenage pregnancy was to improve sex education in schools and to sensitise families to these issues. Six of the eight teenagers wanted more frequent sex education and easier, cheap access to contraception. Only one teenager saw positive consequences stating that teenage pregnancy would ‘avoid operations later in life.’ Discussion: Teenage pregnancy is a recognised problem and strategies in the Masaka region should focus on improving sex education in schools and initiating an organisation that educates and supplies free contraception to teenagers.

Keywords: adolescents, attitudes, teenage pregnancy, Uganda

Procedia PDF Downloads 156

Authors: C. Hernandez-Garcia, P. Adderley, D. Bullard, J. Grames, M. A. Mamun, G. Palacios-Serrano, M. Poelker, M. Stutzman, R. Suleiman, Y. Wang, , S. Zhang

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High-energy nuclear physics experiments performed at the Jefferson Lab (JLab) Continuous Electron Beam Accelerator Facility require a beam of spin-polarized ps-long electron bunches. The electron beam is generated when a circularly polarized laser beam illuminates a GaAs semiconductor photocathode biased at hundreds of kV dc inside an ultra-high vacuum chamber. The photocathode is mounted on highly polished stainless steel electrodes electrically isolated by means of a conical-shape ceramic insulator that extends into the vacuum chamber, serving as the cathode electrode support structure. The assembly is known as a dc photogun, which has to simultaneously meet the following criteria: high voltage to manage space charge forces within the electron bunch, ultra-high vacuum conditions to preserve the photocathode quantum efficiency, no field emission to prevent gas load when field emitted electrons impact the vacuum chamber, and finally no voltage breakdown for robust operation. Over the past decade, JLab has tested and implemented the use of inverted geometry ceramic insulators connected to commercial high voltage cables to operate a photogun at 200kV dc with a 10 cm long insulator, and a larger version at 300kV dc with 20 cm long insulator. Plans to develop a third photogun operating at 400kV dc to meet the stringent requirements of the proposed International Linear Collider are underway at JLab, utilizing even larger inverted insulators. This contribution describes approaches that have been successful in solving challenging problems related to breakdown and field emission, such as triple-point junction screening electrodes, mechanical polishing to achieve mirror-like surface finish and high voltage conditioning procedures with Kr gas to extinguish field emission.

Keywords: electron guns, high voltage techniques, insulators, vacuum insulation

Procedia PDF Downloads 97

Authors: B. Atli-Veltin, A. Vosteen, D. Megan, A. Jedynska, L. K. Cheng

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Composite materials combine the advantages of being lightweight and possessing high strength. This is in particular of interest for the development of large constructions, e.g., aircraft, space applications, wind turbines, etc. One of the shortcomings of using composite materials is the complex nature of the failure mechanisms which makes it difficult to predict the remaining lifetime. Therefore, condition and health monitoring are essential for using composite material for critical parts of a construction. Different types of sensors are used/developed to monitor composite structures. These include ultrasonic, thermography, shearography and fiber optic. The first 3 technologies are complex and mostly used for measurement in laboratory or during maintenance of the construction. Optical fiber sensor can be surface mounted or embedded in the composite construction to provide the unique advantage of in-operation measurement of mechanical strain and other parameters of interest. This is identified to be a promising technology for Structural Health Monitoring (SHM) or Prognostic Health Monitoring (PHM) of composite constructions. Among the different fiber optic sensing technologies, Fiber Bragg Grating (FBG) sensor is the most mature and widely used. FBG sensors can be realized in an array configuration with many FBGs in a single optical fiber. In the current project, different aspects of using embedded FBG for composite wind turbine monitoring are investigated. The activities are divided into two parts. Firstly, FBG embedded carbon composite laminate is subjected to tensile and bending loading to investigate the response of FBG which are placed in different orientations with respect to the fiber. Secondly, the demonstration of using FBG sensor array for temperature and strain sensing and monitoring of a 5 m long scale model of a glass fiber mono-pile is investigated. Two different FBG types are used; special in-house fibers and off-the-shelf ones. The results from the first part of the study are showing that the FBG sensors survive the conditions during the production of the laminate. The test results from the tensile and the bending experiments are indicating that the sensors successfully response to the change of strain. The measurements from the sensors will be correlated with the strain gauges that are placed on the surface of the laminates.

Keywords: Fiber Bragg Gratings, embedded sensors, health monitoring, wind turbine towers

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Authors: Pauline Bredy, Yves Schuurman, David Farrusseng

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To fulfill climate objectives, the production of synthetic e-fuels using CO₂ as a raw material appears as part of the solution. In particular, Power-to-Liquid (PtL) concept combines CO₂ with hydrogen supplied from water electrolysis, powered by renewable sources, which is currently gaining interest as it allows the production of sustainable fossil-free liquid fuels. The proposed process discussed here is an upgrading of the well-known Fischer-Tropsch synthesis. The concept deals with two cascade reactions in one pot, with first the conversion of CO₂ into CO via the reverse water gas shift (RWGS) reaction, which is then followed by the Fischer-Tropsch Synthesis (FTS). Instead of using a Fe-based catalyst, which can carry out both reactions, we have chosen the strategy to decouple the two functions (RWGS and FT) on two different catalysts within the same reactor. The FTS shall shift the equilibrium of the RWGS reaction (which alone would be limited to 15-20% of conversion at 250°C) by converting the CO into hydrocarbons. This strategy shall enable optimization of the catalyst pair and thus lower the temperature of the reaction thanks to the equilibrium shift to gain selectivity in the liquid fraction. The challenge lies in maximizing the activity of the RWGS catalyst but also in the ability of the FT catalyst to be highly selective. Methane production is the main concern as the energetic barrier of CH₄ formation is generally lower than that of the RWGS reaction, so the goal will be to minimize methane selectivity. Here we report the study of different combinations of copper-based RWGS catalysts with different cobalt-based FTS catalysts. We investigated their behaviors under mild process conditions by the use of high-throughput experimentation. Our results show that at 250°C and 20 bars, Cobalt catalysts mainly act as methanation catalysts. Indeed, CH₄ selectivity never drops under 80% despite the addition of various protomers (Nb, K, Pt, Cu) on the catalyst and its coupling with active RWGS catalysts. However, we show that the activity of the RWGS catalyst has an impact and can lead to longer hydrocarbons chains selectivities (C₂⁺) of about 10%. We studied the influence of the reduction temperature on the activity and selectivity of the tandem catalyst system. Similar selectivity and conversion were obtained at reduction temperatures between 250-400°C. This leads to the question of the active phase of the cobalt catalysts, which is currently investigated by magnetic measurements and DRIFTS. Thus, in coupling it with a more selective FT catalyst, better results are expected. This was achieved using a cobalt/iron FTS catalyst. The CH₄ selectivity dropped to 62% at 265°C, 20 bars, and a GHSV of 2500ml/h/gcat. We propose that the conditions used for the cobalt catalysts could have generated this methanation because these catalysts are known to have their best performance around 210°C in classical FTS, whereas the iron catalysts are more flexible but are also known to have an RWGS activity.

Keywords: cobalt-copper catalytic systems, CO₂-hydrogenation, Fischer-Tropsch synthesis, hydrocarbons, low-temperature process

Procedia PDF Downloads 39

Authors: Ugwu O. C., Mamah R. O., Awudu W. S.

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This work is aimed at enhancing signal reception on a mobile radio network and minimizing outage probability in a mobile radio network using adaptive beamforming antenna arrays. In this research work, an empirical real-time drive measurement was done in a cellular network of Globalcom Nigeria Limited located at Ikeja, the headquarters of Lagos State, Nigeria, with reference base station number KJA 004. The empirical measurement includes Received Signal Strength and Bit Error Rate which were recorded for exact prediction of the signal strength of the network as at the time of carrying out this research work. The Received Signal Strength and Bit Error Rate were measured with a spectrum monitoring Van with the help of a Ray Tracer at an interval of 100 meters up to 700 meters from the transmitting base station. The distance and angular location measurements from the reference network were done with the help Global Positioning System (GPS). The other equipment used were transmitting equipment measurements software (Temsoftware), Laptops and log files, which showed received signal strength with distance from the base station. Results obtained were about 11% from the real-time experiment, which showed that mobile radio networks are prone to signal failure and can be minimized using an Adaptive Beamforming Antenna Array in terms of a significant reduction in Bit Error Rate, which implies improved performance of the mobile radio network. In addition, this work did not only include experiments done through empirical measurement but also enhanced mathematical models that were developed and implemented as a reference model for accurate prediction. The proposed signal models were based on the analysis of continuous time and discrete space, and some other assumptions. These developed (proposed) enhanced models were validated using MATLAB (version 7.6.3.35) program and compared with the conventional antenna for accuracy. These outage models were used to manage the blocked call experience in the mobile radio network. 20% improvement was obtained when the adaptive beamforming antenna arrays were implemented on the wireless mobile radio network.

Keywords: beamforming algorithm, adaptive beamforming, simulink, reception

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Authors: Ziani Borhane Eddine Cherif, Hazzi Mohamed, Mouhouche Fazia

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The vegetal extracts of aromatic and medicinal plants start to have much of interest like potential sources of natural bioactive molecules. Many features are conferred by the nature of the chemical function of their major constituents (phenol, alcohol, aldehyde, cetone). This biopotential lets us to focalize on the study of three main biological activities, the antioxidant, antibiotic and insecticidal activities of six Algerian aromatic plants in the aim of making in evidence by the chromatographic analysis (CPG and CG/SM) the phytochemical compounds implicating in this effects. The contents of Oxygenated monoterpenes represented the most prominent group of constituents in the majority of plants. However, the α-Terpineol (28,3%), Carvacrol (47,3%), pulégone (39,5%), Chrysanthenone (27,4%), Thymol 23,9%, γ-Terpinene 23,9% and 2-Undecanone(94%) were the main components. The antioxyding activity of the Essential oils and no-volatils extracts was evaluated in vitro using four tests: inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) radical-scavenging activity (ABTS•+), the thiobarbituric acid reactive substances (TBARS) assays and the reducing power. The measures of the IC50 of these natural compounds revealed potent activity (between 254.64-462.76mg.l-1), almost similar to that of BHT, BHA, Tocopherol and Ascorbic acid (126,4-369,1 mg.l-1) and so far than the Trolox one (IC50= 2,82mg.l-1). Furthermore, three ethanol extracts were found to be remarkably effective toward DPPH and ABTS inhibition, compared to chemical antioxidant BHA and BHT (IC = 9.8±0.1 and 28±0.7 mg.l-1, respectively); for reducing power test it has also exhibited high activity. The study on the insecticidal activity effect by contact, inhalation, fecundity and fertility of Callosobruchus maculatus and Tribolium confusum showed a strong potential biocide reaching 95-100% mortality only after 24 hours. The antibiotic activity of our essential oils were evaluated by a qualitative study (aromatogramme) and quantitative (MIC, MBC and CML) on four bacteria (Gram+ and Gram-) and one strain of pathogenic yeast, the results of these tests showed very interesting action than that induced by the same reference antibiotics (Gentamycin, and Nystatin Ceftatidine) such that the inhibition diameters and MIC values for tested microorganisms were in the range of 23–58 mm and 0.015–0.25%(v/v) respectively.

Keywords: aromatic plants, essential oils, no-volatils extracts, bioactive molecules, antioxidant activity, insecticidal activity, antibiotic activity

Procedia PDF Downloads 206