Search results for: grid-stiffened composite structures

Authors: Chuanxiang Cheng, Tiantian Min, Jin Yue

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Antimicrobial active packaging enables extensive biological effects to improve food safety. However, the efficacy of antimicrobial packaging hinges on factors including the diffusion rate of the active agent toward the food surface, the initial content in the antimicrobial agent, and the targeted food shelf life. Among the possibilities of antimicrobial packaging design, an interesting approach involves the incorporation of volatile antimicrobial agents into the packaging material. In this case, the necessity for direct contact between the active packaging material and the food surface is mitigated, as the antimicrobial agent exerts its action through the packaging headspace atmosphere towards the food surface. However, it still remains difficult to achieve controlled and precise release of bioactive compounds to the specific target location with required quantity in food packaging applications. Remarkably, the development of stimuli-responsive materials for electrospinning has introduced the possibility of achieving controlled release of active agents under specific conditions, thereby yielding enduring biological effects. Relative humidity (RH) for the storage of food categories such as meat and aquatic products typically exceeds 90%. Consequently, high RH can be used as an abiotic trigger for the release of active agents to prevent microbial growth. Hence, a novel RH - responsive polyvinyl alcohol/chitosan (PVA/CS) composite nanofibrous film incorporated with 4-terpineol/β-cyclodextrin inclusion complexes (4-TA@β-CD ICs) was engineered by electrospinning that can be deposited as a functional packaging materials. The characterization results showed the thermal stability of the films was enhanced after the incorporation due to the hydrogen bonds between ICs and polymers. Remarkably, the 4 wt% 4-TA@β-CD ICs/PVA/CS film exhibited enhanced crystallinity, moderate hydrophilic (Water contact angle of 81.53°), light barrier property (Transparency of 1.96%) and water resistance (Water vapor permeability of 3.17 g mm/m2 h kPa). Moreover, this film also showed optimized mechanical performance with a Young’s modulus of 11.33 MPa, a tensile strength of 19.99 MPa and an elongation at break of 4.44 %. Notably, the antioxidant and antibacterial properties of this packaging material were significantly improved. The film demonstrated the half-inhibitory concentrations (IC50) values of 87.74% and 85.11% for scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic) (ABTS) free radicals, respectively, in addition to an inhibition efficiency of 65% against Shewanella putrefaciens, the characteristic bacteria in aquatic products. Most importantly, the film achieved controlled release of 4-TA under high 98% RH by inducing the plasticization of polymers caused by water molecules, swelling of polymer chains, and destruction of hydrogen bonds within the cyclodextrin inclusion complex. Consequently, low relative humidity is suitable for the preservation of nanofibrous film, while high humidity conditions typical in fresh food packaging environments effectively stimulated the release of active compounds in the film. This film with a long-term antimicrobial effect successfully extended the shelf life of Litopenaeus vannamei shrimp to 7 days at 4 °C. This attractive design could pave the way for the development of new food packaging materials.

Keywords: controlled release, electrospinning, nanofibrous film, relative humidity–responsive, shrimp preservation

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Authors: P. Mounnarath, U. Schmitz, Ch. Zhang

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Fragility analysis is an effective tool for the seismic vulnerability assessment of civil structures in the last several years. The design of the expansion joints according to various bridge design codes is almost inconsistent, and only a few studies have focused on this problem so far. In this study, the influence of the expansion joint clearances between the girder ends and the abutment backwalls on the seismic fragility assessment of continuous integral bridge frames is investigated. The gaps (ranging from 60 mm, 150 mm, 250 mm and 350 mm) are designed by following two different bridge design code specifications, namely, Caltrans and Eurocode 8-2. Five bridge models are analyzed and compared. The first bridge model serves as a reference. This model uses three-dimensional reinforced concrete fiber beam-column elements with simplified supports at both ends of the girder. The other four models also employ reinforced concrete fiber beam-column elements but include the abutment backfill stiffness and four different gap values. The nonlinear time history analysis is performed. The artificial ground motion sets, which have the peak ground accelerations (PGAs) ranging from 0.1 g to 1.0 g with an increment of 0.05 g, are taken as input. The soil-structure interaction and the P-Δ effects are also included in the analysis. The component fragility curves in terms of the curvature ductility demand to the capacity ratio of the piers and the displacement demand to the capacity ratio of the abutment sliding bearings are established and compared. The system fragility curves are then obtained by combining the component fragility curves. Our results show that in the component fragility analysis, the reference bridge model exhibits a severe vulnerability compared to that of other sophisticated bridge models for all damage states. In the system fragility analysis, the reference curves illustrate a smaller damage probability in the earlier PGA ranges for the first three damage states, they then show a higher fragility compared to other curves in the larger PGA levels. In the fourth damage state, the reference curve has the smallest vulnerability. In both the component and the system fragility analysis, the same trend is found that the bridge models with smaller clearances exhibit a smaller fragility compared to that with larger openings. However, the bridge model with a maximum clearance still induces a minimum pounding force effect.

Keywords: expansion joint clearance, fiber beam-column element, fragility assessment, time history analysis

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Authors: Kayode A. Olaniyi, Olabanji F. Omotoye, Adeola A. Ogunleye

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Computer system components such as the CPU, the Controllers, and the operating system, work together as a team, and storage or memory is the essential parts of this team apart from the processor. The memory and storage system including processor caches, main memory, and storage, form basic storage component of a computer system. The characteristics of the different types of storage are inherent in the design and the technology employed in the manufacturing. These memory characteristics define the speed, compatibility, cost, volatility, and density of the various storage types. Most computers rely on a hierarchy of storage devices for performance. The effective and efficient use of the memory hierarchy of the computer system therefore is the single most important aspect of computer system design and use. The memory hierarchy is becoming a fundamental performance and energy bottleneck, due to the widening gap between the increasing demands of modern computer applications and the limited performance and energy efficiency provided by traditional memory technologies. With the dramatic development in the computers systems, computer storage has had a difficult time keeping up with the processor speed. Computer architects are therefore facing constant challenges in developing high-speed computer storage with high-performance which is energy-efficient, cost-effective and reliable, to intercept processor requests. It is very clear that substantial advancements in redesigning the existing memory physical and logical structures to meet up with the latest processor potential is crucial. This research work investigates the importance of computer memory (storage) hierarchy in the design of computer systems. The constituent storage types of the hierarchy today were investigated looking at the design technologies and how the technologies affect memory characteristics: speed, density, stability and cost. The investigation considered how these characteristics could best be harnessed for overall efficiency of the computer system. The research revealed that the best single type of storage, which we refer to as ideal memory is that logical single physical memory which would combine the best attributes of each memory type that make up the memory hierarchy. It is a single memory with access speed as high as one found in CPU registers, combined with the highest storage capacity, offering excellent stability in the presence or absence of power as found in the magnetic and optical disks as against volatile DRAM, and yet offers a cost-effective attribute that is far away from the expensive SRAM. The research work suggests that to overcome these barriers it may then mean that memory manufacturing will take a total deviation from the present technologies and adopt one that overcomes the associated challenges with the traditional memory technologies.

Keywords: cache, memory-hierarchy, memory, registers, storage

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Authors: Grace Scaplehorn, Muhammad Adeel Akhtar, Jane Gibson

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Background: Canoe Slalom entails the skilful navigation of a carbon composite canoe or kayak through a series of 18-25 hanging gates, strategically positioned along the course, either upstream or downstream, amidst currents of whitewater rapids in natural and man-made river settings. Athletes compete individually in timed trials, competing for the fastest course time, typically around 80 to 120 seconds. In the new discipline of Kayak Cross, descents of the course are initiated by groups of four athletes freefalling simultaneously from a starting platform situated 3m above the river. Kayak Cross athletes, in contrast to Canoe Slalom, can make physical contact with suspended gates without incurring time penalties and are required to perform a kayak roll half way down the course. The Canoe Slalom World Championships were held at Lee Valley Whitewater Centre, London, from 19th to 24th September 2023. The event comprised 299 international athletes competing for 10 World Championship titles in Canoe/Kayak Slalom events (Olympic Debut Munich 1972), and the new Kayak Cross discipline (Olympic Debut Paris 2024). The inaugural appearance of Kayak Cross at the World Championships occurred in 2017, in Pau, France. There is limited literature surrounding Kayak Cross and the incidence of athlete injuries compared to traditional Canoe Slalom, hence it was felt important to undertake this review to address the perception that the event is dangerous. Aim: The study aimed to quantify and collate data collected from athletes presenting to the event medical centre. Methods: Athletes’ details were collected at initial assessments from the start of the practice period (16th–18th September) and throughout the event. Demographics such as age, sex and nationality were recorded along with presenting complaints, treatment, medication administered and outcome. Specifically, injuries were then sub-classified into body regions. The data does not include athletes who sought medical attention from their own governing body’s medical team. Results: During the 8-day period, there were 11 individual presentations to the medical centre, 3.7% of the athlete population (n=299). The mean age was 23.9 years (n=7), 6 were male (n=10). The most common presentation was minor injury (n=9), with 6 being musculoskeletal and 3 comprising skin damage, followed by insect sting/allergy (n=1) and pain relief requests (n=1). Five presentations were event-related, all being musculoskeletal injuries; 2 shoulder/arm, 1 head/neck, 1 hand/wrist and 1 other (data was not recorded). Of these injuries, the only intervention was 2 cases of 400mg Ibuprofen, which was given to both shoulder/arm injuries. Four of the 11 presentations were pre-existing injuries, which had been exacerbated due to increased intensity of practice. Two patients were advised to return for review, with 100% compliance. There were no unplanned re-presentations, and no emergency transfers to secondary care. Both the Kayak Cross and Canoe Slalom competitions resulted in 1 new event-related athlete presentation each. Conclusion: The event resulted in a negligible incidence of presentations at the medical centre, for both Kayak Cross and Canoe Slalom. This data holds significance in informing risk assessments and medical protocols necessary for the organisation of canoe slalom events.

Keywords: canoe slalom, kayak cross, athlete injuries, event injuries

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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

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Authors: Safar Ghaedrahmati, Leila Soltani

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Population centralization in urban area and metropolitans, especially in developing countries such as Iran increase metropolitan's problems. For few decades, the population of cities in developing countries, including Iran had a higher growth rate than the total growth rate of countries’ population. While in developed countries, the development of the big cities began decades ago and generally allowed for controlled and planned urban expansion, the opposite is the case in developing countries, where rapid urbanization process is characterized by an unplanned existing urban expansion. The developing metropolitan cities have enormous difficulties in coping both with the natural population growth and the urban physical expansion. Iranian cities are usually the heart of economic and cultural changes that have occurred after the Islamic revolution in 1979. These cities are increasingly having impacts via political–economical arrangement and chiefly by urban management structures. Structural features have led to the population growth of cities and urbanization (in number, population and physical frame) and the main problems in them. On the other hand, the lack of birth control policies and the deceptive attractions of cities, particularly big cities, and the birth rate has shot up, something which has occurred mainly in rural regions and small cities. The population of Iran has increased rapidly since 1956. The 1956 and 1966 decennial censuses counted the population of Iran at 18.9 million and 25.7 million, respectively, with a 3.1% annual growth rate during the 1956–1966 period. The 1976 and 1986 decennial censuses counted Iran’s population at 33.7 and 49.4 million, respectively, a 2.7% and 3.9% annual growth rate during the 1966–1976 and 1976–1986 periods. The 1996 count put Iran’s population at 60 million, a 1.96% annual growth rate from 1986–1996 and the 2006 count put Iran population at 72 million. A recent major policy of urban economic and industrial decentralization is a persistent program of the government. The policy has been identified as a result of the massive growth of Tehran in the recent years, up to 9 million by 2010. Part of the growth of the capitally resulted from the lack of economic opportunities elsewhere and in order to redress the developing primacy of Tehran and the domestic pressures which it is undergoing, the policy of decentralization is to be implemented as quickly as possible. Type of research is applied and method of data collection is documentary and methods of analysis are; population analysis with urban system analysis and urban distribution system

Keywords: population centralization, cities of Iran, urban centralization, urban system

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Authors: Cemil Akcay, Goksun Yerlikaya

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Buildings are the living spaces of people with an active role in every aspect of life in today's world. While some structures have survived from the early ages, most of the buildings that completed their lifetime have not transported to the present day. Nowadays, buildings that do not meet the social, economic, and safety requirements of the age return to life with a transformation process. This transformation is called urban transformation. Urban transformation is the renewal of the areas with a risk of disaster and the technological infrastructure required by the structure. The transformation aims to prevent damage to earthquakes and other disasters by rebuilding buildings that have completed their non-earthquake-resistant economic life. It is essential to decide on other issues related to conversion and transformation in places where most of the building stock should transform into the first-degree earthquake belt, such as Istanbul. In urban transformation, property owners, local authority, and contractor must deal at a common point. Considering that hundreds of thousands of property owners are sometimes in the areas of transformation, it is evident how difficult it is to make the deal and decide. For the optimization of these decisions, the use of game theory is foreseeing. The main problem in this study is that the urban transformation is carried out in place, or the building or buildings are transport to a different location. There are many stakeholders in the Istanbul University Cerrahpaşa Medical Faculty Campus, which is planned to be carried out in the process of urban transformation, was tried to solve the game theory applications. An analysis of the decisions given on a real urban transformation project and the logical suitability of decisions taken without the use of game theory were also supervised using game theory. In each step of this study, many decision-makers are classifying according to a specific logical sequence, and in the game trees that emerged as a result of this classification, Nash balances were tried to observe, and optimum decisions were determined. All decisions taken for this project have been subjected to two significant differentiated comparisons using game theory, and as decisions are taken without the use of game theory, and according to the results, solutions for the decision phase of the urban transformation process introduced. The game theory model developed from beginning to the end of the urban transformation process, particularly as a solution to the difficulty of making rational decisions in large-scale projects with many participants in the decision-making process. The use of a decision-making mechanism can provide an optimum answer to the demands of the stakeholders. In today's world for the construction sector, it is also seeing that the game theory is a non-surprising consequence of the fact that it is the most critical issues of planning and making the right decision in future years.

Keywords: urban transformation, the game theory, decision making, multi-actor project

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Authors: Amir Shariffar, Haider Salman, Tanveer Siddique, Omar Manasreh

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According to the recent studies on metal-oxide memristors, researchers tend to improve the stability, endurance, and uniformity of resistive switching (RS) behavior in memristors. Specifically, the main challenge is to prevent abrupt ruptures in the memristor’s filament during the RS process. To address this problem, we are proposing a low-cost hybrid structure of metal oxide quantum dots (QDs) and thin films to control the formation of filaments in memristors. We aim to use metal oxide quantum dots because of their unique electronic properties and quantum confinement, which may improve the resistive switching behavior. QDs have discrete energy spectra due to electron confinement in three-dimensional space. Because of Coulomb repulsion between electrons, only a few free electrons are contained in a quantum dot. This fact might guide the growth direction for the conducting filaments in the metal oxide memristor. As a result, it is expected that QDs can improve the endurance and uniformity of RS behavior in memristors. Moreover, we use a hybrid structure of intrinsic n-type quantum dots and p-type thin films to introduce a potential barrier at the junction that can smooth the transition between high and low resistance states. A bottom-up approach is used for fabricating the proposed memristor using different types of metal-oxide QDs and thin films. We synthesize QDs including, zinc oxide, molybdenum trioxide, and nickel oxide combined with spin-coated thin films of titanium dioxide, copper oxide, and hafnium dioxide. We employ fluorine-doped tin oxide (FTO) coated glass as the substrate for deposition and bottom electrode. Then, the active layer composed of one type of quantum dots, and the opposite type of thin films is spin-coated onto the FTO. Lastly, circular gold electrodes are deposited with a shadow mask by using electron-beam (e-beam) evaporation at room temperature. The fabricated devices are characterized using a probe station with a semiconductor parameter analyzer. The current-voltage (I-V) characterization is analyzed for each device to determine the conduction mechanism. We evaluate the memristor’s performance in terms of stability, endurance, and retention time to identify the optimal memristive structure. Finally, we assess the proposed hypothesis before we proceed to the optimization process for fabricating the memristor.

Keywords: memristor, quantum dot, resistive switching, thin film

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Authors: Ankit Khurana

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The sufficient heat storage capacity or ability to dissipate heat is the most decisive parameter to have an effective and efficient functioning of Friction-based Brake Disc systems. The primary aim of the research was to analyse the effect of multiple coatings on lightweight disk rotors surface which not only alleviates the mass of vehicle & also, augments heat transfer. This research is projected to aid the automobile fraternity with an enunciated view over the thermal aspects in a braking system. The results of the project indicate that with the advent of modern coating technologies a brake system’s thermal curtailments can be removed and together with forced convection, heat transfer processes can see a drastic improvement leading to increased lifetime of the brake rotor. Other advantages of modifying the surface of a lightweight rotor substrate will be to reduce the overall weight of the vehicle, decrease the risk of thermal brake failure (brake fade and fluid vaporization), longer component life, as well as lower noise and vibration characteristics. A mathematical model was constructed in MATLAB which encompassing the various thermal characteristics of the proposed coatings and substrate materials required to approximate the heat flux values in a free and forced convection environment; resembling to a real-time braking phenomenon which could easily be modelled into a full cum scaled version of the alloy brake rotor part in ABAQUS. The finite element of a brake rotor was modelled in a constrained environment such that the nodal temperature between the contact surfaces of the coatings and substrate (Wrought Aluminum alloy) resemble an amalgamated solid brake rotor element. The initial results obtained were for a Plasma Electrolytic Oxidized (PEO) substrate wherein the Aluminum alloy gets a hard ceramic oxide layer grown on its transitional phase. The rotor was modelled and then evaluated in real-time for a constant ‘g’ braking event (based upon the mathematical heat flux input and convective surroundings), which reflected the necessity to deposit a conducting coat (sacrificial) above the PEO layer in order to inhibit thermal degradation of the barrier coating prematurely. Taguchi study was then used to bring out certain critical factors which may influence the maximum operating temperature of a multi-coated brake disc by simulating brake tests: a) an Alpine descent lasting 50 seconds; b) an Autobahn stop lasting 3.53 seconds; c) a Six–high speed repeated stop in accordance to FMVSS 135 lasting 46.25 seconds. Thermal Barrier coating thickness and Vane heat transfer coefficient were the two most influential factors and owing to their design and manufacturing constraints a final optimized model was obtained which survived the 6-high speed stop test as per the FMVSS -135 specifications. The simulation data highlighted the merits for preferring Wrought Aluminum alloy 7068 over Grey Cast Iron and Aluminum Metal Matrix Composite in coherence with the multiple coating depositions.

Keywords: lightweight brakes, surface modification, simulated braking, PEO, aluminum

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Authors: Anne-Marie Dionne

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Teacher reading aloud to students is a practice that is well established in preschool and primary classrooms. Many benefits of this pedagogical activity have been highlighted in multiple studies. However, it has also been shown that teachers are not keen on choosing informational texts for their read aloud, as their selections for this venue are mainly fictional stories, mostly written in a unique narrative story-like structure. Considering that students soon have to read complex informational texts by themselves as they go from one grade to another, there is cause for concern because those who do not benefit from an early exposure to informational texts could be lacking knowledge of informational text structures that they will encounter regularly in their reading. Exposing students to informational texts could be done in different ways in classrooms. However, since read aloud appears to be such a common and efficient practice in preschool and primary grades, it is important to examine more deeply the factors taken into account by teachers when they are selecting their readings for this important teaching activity. Moreover, it seems critical to know why teachers are not inclined to choose more often informational texts when they are reading aloud to their pupils. A group of 22 preschool or primary grade teachers participated in this study. The data collection was done by a survey and an individual semi-structured interview. The survey was conducted in order to get quantitative data on the read-aloud practices of teachers. As for the interviews, they were organized around three categories of questions (exploratory, analytical, opinion) regarding the process of selecting the texts for the read-aloud sessions. A statistical analysis was conducted on the data obtained by the survey. As for the interviews, they were subjected to a content analysis aiming to classify the information collected in predetermined categories such as the reasons given to favor fictional texts over informative texts, the reasons given for avoiding informative texts for reading aloud, the perceptions of the challenges that the informative texts could bring when they are read aloud to students, and the perceived advantages that they would present if they were chosen more often for this activity. Results are showing variable factors that are guiding the teachers when they are making their selection of the texts to be read aloud. As for example, some of them are choosing solely fictional texts because of their convictions that these are more interesting for their students. They also perceive that the informational texts are not good choices because they are not suitable for pleasure reading. In that matter, results are pointing to some interesting elements. Many teachers perceive that read aloud of fictional or informational texts have different goals: fictional texts are read for pleasure and informational texts are read mostly for academic purposes. These results bring out the urgency for teachers to become aware of the numerous benefits that the reading aloud of each type of texts could bring to their students, especially the informational texts. The possible consequences of teachers’ perceptions will be discussed further in our presentation.

Keywords: fictional texts, informational texts, preschool or primary grade teachers, reading aloud

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Authors: Yulii D. Shikhmurzaev

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The modelling of the non-isothermal free-surface flows coupled with the solidification process has become the topic of intensive research with the advent of additive manufacturing, where complex 3-dimensional structures are produced by successive deposition and solidification of microscopic droplets of different materials. The issue is that both the spreading of liquids over solids and the propagation of the solidification front into the fluid and along the solid substrate pose fundamental difficulties for their mathematical modelling. The first of these processes, known as ‘dynamic wetting’, leads to the well-known ‘moving contact-line problem’ where, as shown recently both experimentally and theoretically, the contact angle formed by the free surfac with the solid substrate is not a function of the contact-line speed but is rather a functional of the flow field. The modelling of the propagating solidification front requires generalization of the classical Stefan problem, which would be able to describe the onset of the process and the non-equilibrium regime of solidification. Furthermore, given that both dynamic wetting and solification occur concurrently and interactively, they should be described within the same conceptual framework. The present work addresses this formidable problem and presents a mathematical model capable of describing the key element of additive manufacturing in a self-consistent and singularity-free way. The model is illustrated simple examples highlighting its main features. The main idea of the work is that both dynamic wetting and solidification, as well as some other fluid flows, are particular cases in a general class of flows where interfaces form and/or disappear. This conceptual framework allows one to derive a mathematical model from first principles using the methods of irreversible thermodynamics. Crucially, the interfaces are not considered as zero-mass entities introduced using Gibbsian ‘dividing surface’ but the 2-dimensional surface phases produced by the continuum limit in which the thickness of what physically is an interfacial layer vanishes, and its properties are characterized by ‘surface’ parameters (surface tension, surface density, etc). This approach allows for the mass exchange between the surface and bulk phases, which is the essence of the interface formation. As shown numerically, the onset of solidification is preceded by the pure interface formation stage, whilst the Stefan regime is the final stage where the temperature at the solidification front asymptotically approaches the solidification temperature. The developed model can also be applied to the flow with the substrate melting as well as a complex flow where both types of phase transition take place.

Keywords: dynamic wetting, interface formation, phase transition, solidification

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Authors: Amanda Aliende da Matta

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This communication presents an aspect of phenomenon selection in an applied hermeneutic phenomenology study on care and vulnerability: the need to consider it as a situated universal. For that, we will first present the study and its methodology. Secondly, we will expose the need to understand phenomena as situation-defined, incorporating feminist thought. In an informatics class for 14 year olds, we explained the exercise: students have to make a 5 slide presentation about a topic of their choice. A does it on streetwear, B on Cristiano Ronaldo, C on Marvel, but J did it on Down Syndrome. Introducing it to the class, J explains the physical and cognitive differences caused by trisomy; when asked to explain it further, he says: "they are angels, teacher," and shows us a poster on his cellphone that says: if you laugh at a different child he will laugh with you because his innocence outweighs your ignorance. The anecdote shows, better than any theoretical explanation, something that some vulnerable people have; something beautiful and special but difficult to define. Let's call this something caring. The research has the main objective of accounting for the experience of caregiving in vulnerability, and it will be carried out with Applied Hermeneutic Phenomenology (AHP). The method's objective is to investigate the lived human experience in its pre-reflexive dimension to know its meaning structures. Contrary to other research methods, AHP does not produce theory about a specific context but seeks the meaning of the lived experience, in its characteristic of human experience. However, it is necessary that we understand care as defined in a concrete situation. We cannot start the research with an a priori definitive concept of care, or we would fall into the mistake of closing ourselves to only what we already know, as explained by Levinas. We incorporate, then, the notion of situated universals. Loyal to phenomenology, the definition of the phenomenon should start with an investigation of the word's etymology: the word cura, in its etymological root, means care. And care comes from the Latin word cogitātus/cōgĭto, which means "to pursue something in mind" and "to consider thoroughly." The verb cōgĭto, meanwhile, is composed of co- (altogether) and agitare (to deal with or think committedly about something, to concern oneself with) / ăgĭto (to set in motion, to move). Care, therefore, has in its origin a meditation on something, a concern about something, a verb that has a sense of action and movement. To care is to act out of concern for something/someone. This etymology, though, is not the final definition of the phenomenon, but only its skeleton. It needs to be embodied in the concrete situation to become a possible lived experience. And that means that the lived experience descriptions (LEDs) should be selected by taking into consideration how and if care was engendered in that concrete experience. Defining the phenomenon has to take into consideration situated knowledge.

Keywords: applied hermeneutic phenomenology, care ethics, hermeneutics, phenomenology, situated universalism

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Authors: Paola Leon, Hugo Garcia, Adan Leon, Samuel Munoz

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The enhanced oil recovery by steam injection was considered a process that only generated physical recovery mechanisms. However, there is evidence of the occurrence of a series of chemical reactions, which are called aquathermolysis, which generates hydrogen sulfide, carbon dioxide, methane, and lower molecular weight hydrocarbons. These reactions can be favored by the addition of a catalyst during steam injection; in this way, it is possible to generate the original oil in situ upgrading through the production increase of molecules of lower molecular weight. This additional effect could increase the oil recovery factor and reduce costs in transport and refining stages. Therefore, this research has focused on the experimental evaluation of the catalytic aquathermolysis on a Colombian heavy oil with 12,8°API. The effects of three different catalysts, reaction time, and temperature were evaluated in a batch microreactor. The changes in the Colombian heavy oil were quantified through nuclear magnetic resonance 1H-NMR. The relaxation times interpretation and the absorption intensity allowed to identify the distribution of the functional groups in the base oil and upgraded oils. Additionally, the average number of aliphatic carbons in alkyl chains, the number of substituted rings, and the aromaticity factor were established as average structural parameters in order to simplify the samples' compositional analysis. The first experimental stage proved that each catalyst develops a different reaction mechanism. The aromaticity factor has an increasing order of the salts used: Mo > Fe > Ni. However, the upgraded oil obtained with iron naphthenate tends to form a higher content of mono-aromatic and lower content of poly-aromatic compounds. On the other hand, the results obtained from the second phase of experiments suggest that the upgraded oils have a smaller difference in the length of alkyl chains in the range of 240º to 270°C. This parameter has lower values at 300°C, which indicates that the alkylation or cleavage reactions of alkyl chains govern at higher reaction temperatures. The presence of condensation reactions is supported by the behavior of the aromaticity factor and the bridge carbons production between aromatic rings (RCH₂). Finally, it is observed that there is a greater dispersion in the aliphatic hydrogens, which indicates that the alkyl chains have a greater reactivity compared to the aromatic structures.

Keywords: catalyst, upgrading, aquathermolysis, steam

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Authors: M. Ekiert, T. Uhl, A. Mlyniec

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Tendons are the biological soft tissue structures composed of collagen, proteoglycan, glycoproteins, water and cells of extracellular matrix (ECM). Tendons, which primary function is to transfer force generated by the muscles to the bones causing joints movement, are exposed to many micro and macro damages. In fact, tendons and ligaments trauma are one of the most numerous injuries of human musculoskeletal system, causing for many people (particularly for athletes and physically active people), recurring disorders, chronic pain or even inability of movement. The number of tendons reconstruction and transplantation procedures is increasing every year. Therefore, studies on soft tissues storage conditions (influencing i.e. tissue aging) seem to be an extremely important issue. In this study, an atomic-scale investigation on the kinetics of decomposition of two selected tendon components – collagen type I (which forms a 60-85% of a tendon dry mass) and elastin protein (which combine with ECM creates elastic fibers of connective tissues) is presented. A molecular model of collagen and elastin was developed based on crystal structure of triple-helical collagen-like 1QSU peptide and P15502 human elastin protein, respectively. Each model employed 4 linear strands collagen/elastin strands per unit cell, distributed in 2x2 matrix arrangement, placed in simulation box filled with water molecules. A decomposition phenomena was simulated with molecular dynamics (MD) method using ReaxFF force field and periodic boundary conditions. A set of NVT-MD runs was performed for 1000K temperature range in order to obtained temperature-depended rate of production of decomposition by-products. Based on calculated reaction rates activation energies and pre-exponential factors, required to formulate Arrhenius equations describing kinetics of decomposition of tested soft tissue components, were calculated. Moreover, by adjusting a model developed for collagen, system scalability and correct implementation of the periodic boundary conditions were evaluated. An obtained results provide a deeper insight into decomposition of selected tendon components. A developed methodology may also be easily transferred to other connective tissue elements and therefore might be used for further studies on soft tissues aging.

Keywords: decomposition, molecular dynamics, soft tissue, tendons

Procedia PDF Downloads 201

Authors: Ozan Ozkan, Hilal Turkoglu Sasmazel

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Natural polymers are widely used in tissue engineering applications, because of their biocompatibility, biodegradability and solubility in the physiological medium. On the other hand, synthetic polymers are also widely utilized in tissue engineering applications, because they carry no risk of infectious diseases and do not cause immune system reaction. However, the disadvantages of both polymer types block their individual usages as tissue scaffolds efficiently. Therefore, the idea of usage of natural and synthetic polymers together as a single 3D hybrid scaffold which has the advantages of both and the disadvantages of none has been entered to the literature. On the other hand, even though these hybrid structures support the cell adhesion and/or proliferation, various surface modification techniques applied to the surfaces of them to create topographical changes on the surfaces and to obtain reactive functional groups required for the immobilization of biomolecules, especially on the surfaces of synthetic polymers in order to improve cell adhesion and proliferation. In a study presented here, to improve the surface functionality and topography of the layer by layer electrospun 3D poly-epsilon-caprolactone/chitosan/poly-epsilon-caprolactone hybrid tissue scaffolds by using atmospheric pressure plasma method, thus to improve cell adhesion and proliferation of these tissue scaffolds were aimed. The formation/creation of the functional hydroxyl and amine groups and topographical changes on the surfaces of scaffolds were realized by using two different atmospheric pressure plasma systems (nozzle type and dielectric barrier discharge (DBD) type) carried out under different gas medium (air, Ar+O2, Ar+N2). The plasma modification time and distance for the nozzle type plasma system as well as the plasma modification time and the gas flow rate for DBD type plasma system were optimized with monitoring the changes in surface hydrophilicity by using contact angle measurements. The topographical and chemical characterizations of these modified biomaterials’ surfaces were carried out with SEM and ESCA, respectively. The results showed that the atmospheric pressure plasma modifications carried out with both nozzle type plasma and DBD plasma caused topographical and functionality changes on the surfaces of the layer by layer electrospun tissue scaffolds. However, the shelf life studies indicated that the hydrophilicity introduced to the surfaces was mainly because of the functionality changes. Therefore, according to the optimized results, samples treated with nozzle type air plasma modification applied for 9 minutes from a distance of 17 cm and Ar+O2 DBD plasma modification applied for 1 minute under 70 cm3/min O2 flow rate were found to have the highest hydrophilicity compared to pristine samples.

Keywords: biomaterial, chitosan, hybrid, plasma

Procedia PDF Downloads 263

Authors: Soumyajit Koley, Kuladeep Rajamudili, Supriyo Ganguly

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In recent years, iron-based shape-memory alloys have been emerging as an inexpensive alternative to costly Ni-Ti alloy and thus considered suitable for many different applications in civil structures. Fe-17Mn-10Cr-5Si-4Ni-0.5V-0.5C alloy contains 37 wt.% of total solute elements. Such complex multi-component metallurgical system often leads to severe solute segregation and solidification cracking. Wire-arc additive manufacturing (WAAM) of Fe-17Mn-10Cr-5Si-4Ni-0.5V-0.5C alloy was attempted using a cold-wire fed plasma arc torch attached to a 6-axis robot. Self-standing walls were manufactured. However, multiple vertical cracks were observed after deposition of around 15 layers. Microstructural characterization revealed open surfaces of dendrites inside the crack, confirming these cracks as solidification cracks. Machine hammer peening (MHP) process was adopted on each layer to cold work the newly deposited alloy. Effect of MHP traverse speed were varied systematically to attain a window of operation where cracking was completely stopped. Microstructural and textural analysis were carried out further to correlate the peening process to microstructure.MHP helped in many ways. Firstly, a compressive residual stress was induced on each layer which countered the tensile residual stress evolved from solidification process; thus, reducing net tensile stress on the wall along its length. Secondly, significant local plastic deformation from MHP followed by the thermal cycle induced by deposition of next layer resulted into a recovered and recrystallized equiaxed microstructure instead of long columnar grains along the vertical direction. This microstructural change increased the total crack propagation length and thus, the overall toughness. Thirdly, the inter-layer peening significantly reduced the strong cubic {001} crystallographic texture formed along the build direction. Cubic {001} texture promotes easy separation of planes and easy crack propagation. Thus reduction of cubic texture alleviates the chance of cracking.

Keywords: Iron-based shape-memory alloy, wire-arc additive manufacturing, solidification cracking, inter-layer cold working, machine hammer peening

Procedia PDF Downloads 60

Authors: A. G. Pershina, P. S. Postnikov, M. E. Trusova, D. O. Burlakova, A. E. Sazonov

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Invention of magnetic-fluorescent nanocomposites is a rapidly developing area of research. The magnetic-fluorescent nanocomposite attractiveness is connected with the ability of simultaneous management and control of such nanocomposites by two independent methods based on different physical principles. These nanocomposites are applied for the solution of various essential scientific and experimental biomedical problems. The aim of this research is development of principle approach to nanobiohybrid structures with magnetic and fluorescent properties design. The surface of carbon-coated iron nanoparticles (Fe@C) were covalently modified by 4-carboxy benzenediazonium tosylate. Recombinant fluorescent protein TagGFP2 (Eurogen) was obtained in E. coli (Rosetta DE3) by standard laboratory techniques. Immobilization of TagGFP2 on the nanoparticles surface was provided by the carbodiimide activation. The amount of COOH-groups on the nanoparticle surface was estimated by elemental analysis (Elementar Vario Macro) and TGA-analysis (SDT Q600, TA Instruments. Obtained nanocomposites were analyzed by FTIR spectroscopy (Nicolet Thermo 5700) and fluorescence microscopy (AxioImager M1, Carl Zeiss). Amount of the protein immobilized on the modified nanoparticle surface was determined by fluorimetry (Cary Eclipse) and spectrophotometry (Unico 2800) with the help of preliminary obtained calibration plots. In the FTIR spectra of modified nanoparticles the adsorption band of –COOH group around 1700 cm-1 and bands in the region of 450-850 cm-1 caused by bending vibrations of benzene ring were observed. The calculated quantity of active groups on the surface was equal to 0,1 mmol/g of material. The carbodiimide activation of COOH-groups on nanoparticles surface results to covalent immobilization of TagGFP2 fluorescent protein (0.2 nmol/mg). The success of immobilization was proved by FTIR spectroscopy. Protein characteristic adsorption bands in the region of 1500-1600 cm-1 (amide I) were presented in the FTIR spectrum of nanocomposite. The fluorescence microscopy analysis shows that Fe@C-TagGFP2 nanocomposite possesses fluorescence properties. This fact confirms that TagGFP2 protein retains its conformation due to immobilization on nanoparticles surface. Magnetic-fluorescent nanocomposite was obtained as a result of unique design solution implementation – the fluorescent protein molecules were fixed to the surface of superparamagnetic carbon-coated iron nanoparticles using original diazonium salts.

Keywords: carbon-coated iron nanoparticles, diazonium salts, fluorescent protein, immobilization

Procedia PDF Downloads 333

Authors: El Hatka Hicham, Hafidi Youssef, Saghiri Khalid, Ittobane Najim

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Flexible polyurethane foam (FPUF) is a low-density cellular material generally used as a cushioning material in many applications such as furniture, bedding, packaging, etc. It is commercially produced during a continuous process, where a reactive mixture of foam chemicals is poured onto a moving conveyor. FPUFs are produced by the catalytic balancing of two reactions involved, the blowing reaction (isocyanate-water) and the gelation reaction (isocyanate-polyol). The microstructure of FPUF is generally composed of soft phases (polyol phases) and rigid domains that separate into two domains of different sizes: the rigid polyurea microdomains and the macrodomains (larger aggregates). The morphological features of FPUF are strongly influenced by the phase separation morphology that plays a key role in determining the global FPUF properties. This phase-separated morphology results from a thermodynamic incompatibility between soft segments derived from aliphatic polyether and hard segments derived from the commonly used aromatic isocyanate. In order to improve the properties of FPUF against the different stresses faced by this material during its use, we report in this work a study of the phase separation phenomenon in FPUF that has been examined using SAXS WAXS and FTIR. Indeed, we have studied with these techniques the effect of water, isocyanates, and alkaline chlorides on the phase separation behavior. SAXS was used to study the morphology of the microphase separated, WAXS to examine the nature of the hard segment packing, and FTIR to investigate the hydrogen bonding characteristics of the materials studied. The prepared foams were shown to have different levels of urea phase connectivity; the increase in water content in the FPUF formulation leads to an increase in the amount of urea formed and consequently the increase of the size of urea aggregates formed. Alkali chlorides (NaCl, KCl, and LiCl) incorporated into FPUF formulations show that is the ability to prevent hydrogen bond formation and subsequently alter the rigid domains. FPUFs prepared by different isocyanate structures showed that urea aggregates are difficult to be formed in foams prepared by asymmetric diisocyanate, while are more easily formed in foams prepared by symmetric and aliphatic diisocyanate.

Keywords: flexible polyurethane foam, hard segments, phase separation, soft segments

Procedia PDF Downloads 143

Authors: Nalluri Lakshmi Ramu, C. Venkat Nihit, Narayana Kumar, Dillep

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Masonry bridges are the iconic heritage transportation infrastructure throughout the world. Continuous increase in traffic loads and speed have kept engineers in dilemma about their structural performance and capacity. Henceforth, research community has an urgent need to propose an effective methodology and validate on real-time bridges. The presented research aims to assess the structural health of an Eighty-year-old masonry railway bridge in India using wireless accelerometer sensors. The bridge consists of 44 spans with length of 24.2 m each and individual pier is 13 m tall laid on well foundation. To calculate the dynamic characteristic properties of the bridge, ambient vibrations were recorded from the moving traffic at various speeds and the same are compared with the developed three-dimensional numerical model using finite element-based software. The conclusions about the weaker or deteriorated piers are drawn from the comparison of frequencies obtained from the experimental tests conducted on alternative spans. Masonry is a heterogeneous anisotropic material made up of incoherent materials (such as bricks, stones, and blocks). It is most likely the earliest largely used construction material. Masonry bridges, which were typically constructed of brick and stone, are still a key feature of the world's highway and railway networks. There are 1,47,523 railway bridges across India and about 15% of these bridges are built by masonry, which are around 80 to 100 year old. The cultural significance of masonry bridges cannot be overstated. These bridges are considered to be complicated due to the presence of arches, spandrel walls, piers, foundations, and soils. Due to traffic loads and vibrations, wind, rain, frost attack, high/low temperature cycles, moisture, earthquakes, river overflows, floods, scour, and soil under their foundations may cause material deterioration, opening of joints and ring separation in arch barrels, cracks in piers, loss of brick-stones and mortar joints, distortion of the arch profile. Few NDT tests like Flat jack Tests are being employed to access the homogeneity, durability of masonry structure, however there are many drawbacks because of the test. A modern approach of structural health assessment of masonry structures by vibration analysis, frequencies and stiffness properties is being explored in this paper.

Keywords: masonry bridges, condition assessment, wireless sensors, numerical analysis modal frequencies

Procedia PDF Downloads 159

Authors: Lauren Kathryn Stretch

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A study was conducted in the underprivileged setting of Nelson Mandela Bay, South Africa in order to monitor the progress of learners whose teachers receive training through the Early Inspiration Training Programme. Through tracking children’s growth & development, the effectiveness of the practitioner-training programme, which focuses on empowering women from underprivileged communities in South Africa, was analyzed. The aim was to identify impact & reach and to assess the effectiveness of this intervention programme through identifying impact on children’s growth and development. A Pre- and Post-Test was administered on about 850 young children in Pre-Grade R and Grade R classes in order to understand children’s ability level & the growth that would be evident as a result of effective teacher training. A pre-test evaluated the level of each child’s abilities, including physical-motor development, language, and speech development, cognitive development including visual perceptual skills, social-emotional development & play development. This was followed by a random selection of the classes of children into experimental and control groups. The experimental group’s teachers (practitioners) received 8-months of training & intervention, as well as mentorship & support. After the 8-month training programme, children from the experimental & control groups underwent post-assessment. The results indicate that the impact of effective practitioner training and enhancing a deep understanding of stimulation on young children, that this understanding is implemented in the classroom, highlighting the areas of growth & development in the children whose teachers received additional training & support, as compared to those who did not receive additional training. Monitoring & Evaluation systems not only track children’s ability levels, but also have a core focus on reporting systems, mentorship and providing ongoing support. As a result of the study, an Online Application (for Apple or Android Devices) was developed which is used to track children’s growth via age-appropriate assessments. The data is then statistically analysed to provide direction for relevant & impactful intervention. The App also focuses on effective reporting strategies, structures, and implementation to support organizations working with young children & maximize on outcomes.

Keywords: early childhood development, developmental child assessments, online application, monitoring and evaluating online

Procedia PDF Downloads 184

Authors: Navid Nasrolah Mazandarani, Faezeh Mohammadi Tahrodi, Jr., Norshida Ujang, Richard Jan Pech

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Human evolution has designed us to be dependent on social and natural settings, but designed of our modern cities often ignore this fact. It is evident that high-rise buildings dominate most metropolitan city centers. As a result urban parks are very limited and in many cases are not socially responsive to our social needs in these urban ‘jungles’. This paper emphasizes the functions of urban morphology in supporting socialization in Lake Garden, one of the main urban parks in Kuala Lumpur, Malaysia. It discusses two relevant theories; first the concept of users’ experience coined by Kevin Lynch (1960) which states that way-finding is related to the process of forming mental maps of environmental surroundings. Second, the concept of social activity coined by Jan Gehl (1987) which holds that urban public spaces can be more attractive when they provide welcoming places in which people can walk around and spend time. Until recently, research on socio-spatial behavior mainly focused on social ties, place attachment and human well-being; with less focus on the spatial dimension of social behavior. This paper examines the socio-spatial behavior within the spatial structure of the urban park by exploring the relationship between way-finding and social activity. The urban structures defined by the paths and nodes were analyzed as the fundamental topological structure of space to understand their effects on the social engagement pattern. The study uses a photo questionnaire survey to inspect the spatial dimension in relation to the social activities within paths and nodes. To understand the legibility of the park, spatial cognition was evaluated using sketch maps produced by 30 participants who visited the park. The results of the sketch mapping indicated that a spatial image has a strong interrelation with socio-spatial behavior. Moreover, an integrated spatial structure of the park generated integrated use and social activity. It was found that people recognized and remembered the spaces where they engaged in social activities. They could experience the park more thoroughly, when they found their way continuously through an integrated park structure. Therefore, the benefits of both perceptual and social dimensions of planning and design happened simultaneously. The findings can assist urban planners and designers to redevelop urban parks by considering the social quality design that contributes to clear mental images of these places.

Keywords: spatial structure, social activities, sketch map, urban park, way-finding

Procedia PDF Downloads 295

Authors: Khodzhaberdi Allaberdiev

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Aromaticity, one of the most important concepts in organic chemistry, has attracted considerable interest from both experimentalists and theoreticians. The geometry optimization of p-substituted o-(N-dialkyl)aminomethylphenols, o-DEAMPH XC₆ H₅CH ₂Y (X=p-OCH₃, CH₃, H, F, Cl, Br, COCH₃, COOCH₃, CHO, CN and NO₂, Y=o-N (C₂H₅)₂, o-DEAMPHs have been performed in the gas phase using the B3LYP/6-311+G(d,p) level. Aromaticities of the considered molecules were investigated using different indices included geometrical (HOMA and Bird), electronic (FLU, PDI and SA) magnetic (NICS(0), NICS(1) and NICS(1)zz indices. The linear dependencies were obtained between some aromaticity indices. The best correlation is observed between the Bird and PDI indices (R² =0.9240). However, not all types of indices or even different indices within the same type correlate well among each other. Surprisingly, for studied molecules in which geometrical and electronic cannot correctly give the aromaticity of ring, the magnetism based index successfully predicts the aromaticity of systems. 1H NMR spectra of compounds were obtained at B3LYP/6–311+G(d,p) level using the GIAO method. Excellent linear correlation (R²= 0.9996) between values the chemical shift of hydrogen atom obtained experimentally of 1H NMR and calculated using B3LYP/6–311+G(d,p) demonstrates a good assignment of the experimental values chemical shift to the calculated structures of o-DEAMPH. It is found that the best linear correlation with the Hammett substituent constants is observed for the NICS(1)zz index in comparison with the other indices: NICS(1)zz =-21.5552+1,1070 σp- (R²=0.9394). The presence intramolecular hydrogen bond in the studied molecules also revealed changes the aromatic character of substituted o-DEAMPHs. The HOMA index predicted for R=NO2 the reduction in the π-electron delocalization of 3.4% was about double that observed for p-nitrophenol. The influence intramolecular H-bonding on aromaticity of benzene ring in the ground state (S0) are described by equations between NICS(1)zz and H-bond energies: experimental, Eₑₓₚ, predicted IR spectroscopical, Eν and topological, EQTAIM with correlation coefficients R² =0.9666, R² =0.9028 and R² =0.8864, respectively. The NICS(1)zz index also correlates with usual descriptors of the hydrogen bond, while the other indices do not give any meaningful results. The influence of the intramolecular H-bonding formation on the aromaticity of some substituted o-DEAMPHs is criteria to consider the multidimensional character of aromaticity. The linear relationships as well as revealed between NICS(1)zz and both pyramidality nitrogen atom, ΣN(C₂H₅)₂ and dihedral angle, φ CAr – CAr -CCH₂ –N, to characterizing out-of-plane properties.These results demonstrated the nonplanar structure of o-DEAMPHs. Finally, when considering dependencies of NICS(1)zz, were excluded data for R=H, because the NICS(1) and NICS(1)zz values are the most negative for unsubstituted DEAMPH, indicating its highest aromaticity; that was not the case for NICS(0) index.

Keywords: aminomethylphenols, DFT, aromaticity, correlations

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Authors: Maria Ahmad, Michael Page, Danë Goodsman

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‘Educational’ debriefing – a construct distinct from clinical debriefing – is used following simulated scenarios and is central to learning and development in fields ranging from aviation to emergency medicine. However, little research into educational debriefing in prehospital medicine exists. This qualitative study explored the facilitation and effects of prehospital educational debriefing and identified obstacles to debriefing, using the London’s Air Ambulance Pre-Hospital Care Course (PHCC) as a model. Method: Ethnographic observations of moulages and debriefs were conducted over two consecutive days of the PHCC in October 2019. Detailed contemporaneous field notes were made and analysed thematically. Subsequently, seven one-to-one, semi-structured interviews were conducted with four PHCC debrief facilitators and three course participants to explore their experiences of prehospital educational debriefing. Interview data were manually transcribed and analysed thematically. Results: Four overarching themes were identified: the approach to the facilitation of debriefs, effects of debriefing, facilitator development, and obstacles to debriefing. The unpredictable debriefing environment was seen as both hindering and paradoxically benefitting educational debriefing. Despite using varied debriefing structures, facilitators emphasised similar key debriefing components, including exploring participants’ reasoning and sharing experiences to improve learning and prevent future errors. Debriefing was associated with three principal effects: releasing emotion; learning and improving, particularly participant compound learning as they progressed through scenarios; and the application of learning to clinical practice. Facilitator training and feedback were central to facilitator learning and development. Several obstacles to debriefing were identified, including mismatch of participant and facilitator agendas, performance pressure, and time. Interestingly, when used appropriately in the educational environment, these obstacles may paradoxically enhance learning. Conclusions: Educational debriefing in prehospital medicine is complex. It requires the establishment of a safe learning environment, an understanding of participant agendas, and facilitator experience to maximise participant learning. Aspects unique to prehospital educational debriefing were identified, notably the unpredictable debriefing environment, interdisciplinary working, and the paradoxical benefit of educational obstacles for learning. This research also highlights aspects of educational debriefing not extensively detailed in the literature, such as compound participant learning, display of ‘professional honesty’ by facilitators, and facilitator learning, which require further exploration. Future research should also explore educational debriefing in other prehospital services.

Keywords: debriefing, prehospital medicine, prehospital medical education, pre-hospital care course

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Authors: Emre Kara, Metehan Demir, Şura Karakuzu, Kadir Koç, Ahmet F. Geylan, Halil Aykul

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While the polymeric foam cored sandwiches have been realized for many years, recently there is a growing and outstanding interest on the use of sandwiches consisting of aluminum foam core because of their some of the distinct mechanical properties such as high bending stiffness, high load carrying and energy absorption capacities. These properties make them very useful in the transportation industry (automotive, aerospace, shipbuilding industry), where the "lightweight design" philosophy and the safety of vehicles are very important aspects. Therefore, in this study, the sandwich panels with aluminum alloy foam core and various types and thicknesses of glass fiber reinforced polymer (GFRP) skins produced via Vacuum Assisted Resin Transfer Molding (VARTM) technique were obtained by using a commercial toughened epoxy based adhesive with two components. The aim of this contribution was the analysis of the bending response of sandwiches with various glass fiber reinforced polymer skins. The three point bending tests were performed on sandwich panels at different values of support span distance using a universal static testing machine in order to clarify the effects of the type and thickness of the GFRP skins in terms of peak load, energy efficiency and absorbed energy values. The GFRP skins were easily bonded to the aluminum alloy foam core under press machine with a very low pressure. The main results of the bending tests are: force-displacement curves, peak force values, absorbed energy, collapse mechanisms and the influence of the support span length and GFRP skins. The obtained results of the experimental investigation presented that the sandwich with the skin made of thicker S-Glass fabric failed at the highest load and absorbed the highest amount of energy compared to the other sandwich specimens. The increment of the support span distance made the decrease of the peak force and absorbed energy values for each type of panels. The common collapse mechanism of the panels was obtained as core shear failure which was not affected by the skin materials and the support span distance.

Keywords: aluminum foam, collapse mechanisms, light-weight structures, transport application

Procedia PDF Downloads 389

Authors: Anjali Uday, Yuting Wang, Andres Alfonso Pena Olare

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The Discrete Element Method is a promising approach to modeling microscopic behaviors of granular materials. The quality of the simulations however depends on the model parameters utilized. The present study focuses on calibration and validation of the discrete element parameters for Cuxhaven sand based on the experimental data from triaxial and oedometer tests. A sensitivity analysis was conducted during the sample preparation stage and the shear stage of the triaxial tests. The influence of parameters like rolling resistance, inter-particle friction coefficient, confining pressure and effective modulus were investigated on the void ratio of the sample generated. During the shear stage, the effect of parameters like inter-particle friction coefficient, effective modulus, rolling resistance friction coefficient and normal-to-shear stiffness ratio are examined. The calibration of the parameters is carried out such that the simulations reproduce the macro mechanical characteristics like dilation angle, peak stress, and stiffness. The above-mentioned calibrated parameters are then validated by simulating an oedometer test on the sand. The oedometer test results are in good agreement with experiments, which proves the suitability of the calibrated parameters. In the next step, the calibrated and validated model parameters are applied to forecast the micromechanical behavior including the evolution of contact force chains, buckling of columns of particles, observation of non-coaxiality, and sample inhomogeneity during a simple shear test. The evolution of contact force chains vividly shows the distribution, and alignment of strong contact forces. The changes in coordination number are in good agreement with the volumetric strain exhibited during the simple shear test. The vertical inhomogeneity of void ratios is documented throughout the shearing phase, which shows looser structures in the top and bottom layers. Buckling of columns is not observed due to the small rolling resistance coefficient adopted for simulations. The non-coaxiality of principal stress and strain rate is also well captured. Thus the micromechanical behaviors are well described using the calibrated and validated material parameters.

Keywords: discrete element model, parameter calibration, triaxial test, oedometer test, simple shear test

Procedia PDF Downloads 111

Authors: Martina Šutovská, Marta Jošková, Ivana Kazimierová, Lenka Pappová, Maroš Adamkov, Soňa Fraňová

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Bronchial asthma is characterized by increased bronchoconstrictor responses to provoking agonists, airway inflammation and remodeling. All these processes involve Ca2+ influx through Ca2+-release-activated Ca2+ channels (CRAC) that are widely expressed in immune, respiratory epithelium and airway smooth muscle (ASM) cells. Our previous study pointed on possible therapeutic potency of CRAC blockers using experimental guinea pigs asthma model. Presented work analyzed complex anti-asthmatic effect of long-term administered CRAC blocker, including impact on allergic inflammation, airways hyperreactivity, and remodeling and mucociliary clearance. Ovalbumin-induced allergic inflammation of the airways according to Franova et al. was followed by 14 days lasted administration of CRAC blocker (3-fluoropyridine-4-carboxylic acid, FPCA) in the dose 1.5 mg/kg bw. For comparative purposes salbutamol, budesonide and saline were applied to control groups. The anti-inflammatory effect of FPCA was estimated by serum and bronchoalveolar lavage fluid (BALF) changes in IL-4, IL-5, IL-13 and TNF-α analyzed by Bio-Plex® assay as well as immunohistochemical staining focused on assessment of tryptase and c-Fos positivity in pulmonary samples. The in vivo airway hyperreactivity was evaluated by Pennock et al. and by organ tissue bath methods in vitro. The immunohistochemical changes in ASM actin and collagen III layer as well as mucin secretion evaluated anti-remodeling effect of FPCA. The measurement of ciliary beat frequency (CBF) in vitro using LabVIEW™ Software determined impact on mucociliary clearance. Long-term administration of FPCA to sensitized animals resulted in: i. Significant decrease in cytokine levels, tryptase and c-Fos positivity similar to budesonide effect; ii.Meaningful decrease in basal and bronchoconstrictors-induced in vivo and in vitro airway hyperreactivity comparable to salbutamol; iii. Significant inhibition of airway remodeling parameters; iv. Insignificant changes in CBF. All these findings confirmed complex anti-asthmatic effect of CRAC channels blocker and evidenced these structures as the rational target in the treatment of allergic bronchial asthma.

Keywords: allergic asthma, CRAC channels, cytokines, respiratory epithelium

Procedia PDF Downloads 511

Authors: Gurkirandeep Kaur, Rana Pratap Yadav

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This experimental study is aimed to examine the radiation characteristics of different plasma structures of a surface wave-driven plasma antenna by an automated measuring system. In this study, a 30 cm long plasma column of argon gas with a diameter of 3 cm is excited by surface wave discharge mechanism operating at 13.56 MHz with RF power level up to 100 Watts and gas pressure between 0.01 to 0.05 mb. The study reveals that a single structured plasma monopole can be modified into an array of plasma antenna elements by forming multiple striations or plasma blobs inside the discharge tube by altering the values of plasma properties such as working pressure, operating frequency, input RF power, discharge tube dimensions, i.e., length, radius, and thickness. It is also reported that plasma length, electron density, and conductivity are functions of operating plasma parameters and controlled by changing working pressure and input power. To investigate the antenna radiation efficiency for the far-field region, an automation-based radiation measuring system has been fabricated and presented in detail. This developed automated system involves a combined setup of controller, dc servo motors, vector network analyzer, and computing device to evaluate the radiation intensity, directivity, gain and efficiency of plasma antenna. In this system, the controller is connected to multiple motors for moving aluminum shafts in both elevation and azimuthal plane whereas radiation from plasma monopole antenna is measured by a Vector Network Analyser (VNA) which is further wired up with the computing device to display radiations in polar plot forms. Here, the radiation characteristics of both continuous and array plasma monopole antenna have been studied for various working plasma parameters. The experimental results clearly indicate that the plasma antenna is as efficient as a metallic antenna. The radiation from plasma monopole antenna is significantly influenced by plasma properties which provides a wider range in radiation pattern where desired radiation parameters like beam-width, the direction of radiation, radiation intensity, antenna efficiency, etc. can be achieved in a single monopole. Due to its wide range of selectivity in radiation pattern; this can meet the demands of wider bandwidth to get high data speed in communication systems. Moreover, this developed system provides an efficient and cost-effective solution for measuring the radiation pattern in far-field zone for any kind of antenna system.

Keywords: antenna radiation characteristics, dynamically reconfigurable, plasma antenna, plasma column, plasma striations, surface wave

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Authors: Zeynep İnan Ocak, Gülsün Tanyeli

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One of the most important architectural types of Islamic architecture is madrasah used as educational institutions, hospital or observatory. This type of buildings has one or two storeys, central open or closed courtyards, four iwans and students cells located among the iwans. The main characteristic of the designs featured in the portals. The Islamic art features and adornments are seen well on these buildings made of stone. The earliest examples date to late 12th century in Anatolia after the Battle of Manzikert. Under the Seljuks rule over the one thousand facilities were built in 12th and 13th centuries and there are one hundred thirty five madrasah in total list. But today no all of them are conserved only forty percent are remained. The Seljuks madrasah located in many Anatolian were registered as immovable cultural property in several times by Turkish Culture and Tourism Ministry. The first Turkish buildings inscribed on the World Heritage List are the Great Mosque and Hospital of Divriği in 1985. Also the nominated site named as Anatolian Seljuks Madrasah is in the tentative list of UNESCO World Heritage in 2014. The property is composed some of notable madrasah such as İnce Minareli Madrasah and Karatay Madrasah in Konya; Çifte Madrasah and Sahibiye Madrasah in Kayseri; Buruciye Madrasah, Çifte Minareli Madrasah and Gök Madrasah in Sivas; Çifte Minareli Madrasah and Yakutiye Madrasah in Erzurum; Cacabey Madrasah in Kirşehir. Certainly the advantage of tourism is important for conducting the preservation of heritage. It offers much kind of cultural heritage products by means of visiting monuments. In spite of advantage of tourism, it can be the negative effects of tourism on sites and places of cultural significance. While assisting and guiding the conservation works of madrasah, it should be get reference to international charters and other doctrinal texts about the relation between heritage and tourism. Thereby the monuments will be conserved in good condition promoting by tourism. It should be plan a project about the correlation of visitors and heritage to focus on theme of Seljuks architecture. This study aims to set out the principles about the conservation of madrasah as world heritage taking advantages of tourism. The madrasah as a heritage should be evaluated not only a monument but also cultural route. So the cultural route for madrasah is determined by means of a journey through space and time, how the heritage of the different Anatolian cities. Also the cultural route is created visiting both the madrasah and the other medieval structures. In this study, the route, the principles, relation of tourism are represented considering the conservation of Seljuks madrasah.

Keywords: architectural heritage, cultural routes, Seljuks madrasah, Anatolia

Procedia PDF Downloads 266

Authors: Youlu Huang, Huanjun Jiang

Abstract:

A large number of old masonry buildings built in the last century still remain in the city. It generates the problems of unsafety, obsolescence, and non-habitability. In recent years, many old buildings have been reconstructed through renovating façade, strengthening, and adding floors. However, most projects only provide a solution for a single problem. It is difficult to comprehensively solve problems of poor safety and lack of building functions. Therefore, a comprehensive functional renovation program of adding reinforced concrete frame story at the bottom via integrally lifting the building and then strengthening the building was put forward. Based on field measurement and YJK calculation software, the seismic performance of an actual three-story masonry structure in Shanghai was identified. The results show that the material strength of masonry is low, and the bearing capacity of some masonry walls could not meet the code requirements. The elastoplastic time history analysis of the structure was carried out by using SAP2000 software. The results show that under the 7 degrees rare earthquake, the seismic performance of the structure reaches 'serious damage' performance level. Based on the code requirements of the stiffness ration of the bottom frame (lateral stiffness ration of the transition masonry story and frame story), the bottom frame story was designed. The integral lifting process of the masonry building was introduced based on many engineering examples. The reinforced methods for the bottom frame structure strengthened by the steel-reinforced mesh mortar surface layer (SRMM) and base isolators, respectively, were proposed. The time history analysis of the two kinds of structures, under the frequent earthquake, the fortification earthquake, and the rare earthquake, was conducted by SAP2000 software. For the bottom frame structure, the results show that the seismic response of the masonry floor is significantly reduced after reinforced by the two methods compared to the masonry structure. The previous earthquake disaster indicated that the bottom frame is vulnerable to serious damage under a strong earthquake. The analysis results showed that under the rare earthquake, the inter-story displacement angle of the bottom frame floor meets the 1/100 limit value of the seismic code. The inter-story drift of the masonry floor for the base isolated structure under different levels of earthquakes is similar to that of structure with SRMM, while the base-isolated program is better to protect the bottom frame. Both reinforced methods could significantly improve the seismic performance of the bottom frame structure.

Keywords: old buildings, adding story, seismic strengthening, seismic performance

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Authors: Lise P. Labéjof, Ivna Mororó, Raquel G. Bastos, Maria Isabel G. Severo, Arno H. de Oliveira

Abstract:

This work presents an alternative mode of intestine mucosa renewal that may allow to better understand the total loss of villi after irradiation. It was tested a morphological method of 3d reconstruction using micrographs of serial sections of rat duodenum. We used hundreds of sections of each specimen of duodenum placed on glass slides and examined under a light microscope. Those containing the detachment, approximately a dozen, were chosen for observation under a transmission electron microscope (TEM). Each of these sections was glued on a block of epon resin and recut into a hundred of 60 nm-thick sections. Ribbons of these ultrathin sections were distributed on a series of copper grids in the same order of appearance than during the process of microstomia. They were then stained by solutions of uranyl and lead salts and observed under a TEM. The sections were pictured and the electron micrographs showing signs of cells detachment were transferred into two softwares, ImageJ to align the cellular structures and Reconstruct to realize the 3d reconstruction. It has been detected epithelial cells that exhibited all signs of programmed cell death and localized at the villus-crypt junction. Their nucleus was irregular in shape with a condensed chromatin in clumps. Their cytoplasm was darker than that of neighboring cells, containing many swollen mitochondria. In some places of the sections, we could see intercellular spaces enlarged by the presence of shrunk cells which displayed a plasma membrane with an irregular shape in thermowell as if the cell interdigitations would distant from each other. The three-dimensional reconstruction of the crypts has allowed observe gradual loss of intercellular contacts of crypt cells in the longitudinal plan of the duodenal mucosa. In the transverse direction, there was a gradual increase of the intercellular space as if these cells moved away from one another. This observation allows assume that the gradual remoteness of the cells at the villus-crypt junction is the beginning of the mucosa detachment. Thus, the shrinking of cells due to apoptosis is the way that they detach from the mucosa and progressively the villi also. These results are in agreement with our initial hypothesis and thus have demonstrated that the villi become detached from the mucosa at the villus-crypt junction by the programmed cell death process. This type of loss of entire villus helps explain the rapid denudation of the intestinal mucosa in case of irradiation.

Keywords: 3dr, transmission electron microscopy, ionizing radiations, rat small intestine, apoptosis

Procedia PDF Downloads 371