Search results for: sulfonic cation exchange resin

Authors: Eric Beyegue, Boris Azantza, Judith Laure Ngondi, Julius E. Oben

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Background: It is clearly that phytochemical constituents of plants in relation exhibit free radical scavenging, antioxidant and glycosylation properties. This study investigated the in vitro antioxidant and free radical scavenging, inhibited activities against α-amylase and invertase enzymes of stem bark extracts C. edulis (Olacaceae). Methods: Four extracts (hexane, dichloromethane, ethanol and aqueous) from the barks of C. edulis were used in this study. Colorimetric in vitro methods were using for evaluate free radical scavenging activity DPPH, ABTS, NO, OH, antioxidant capacity, glycosylation activity, inhibition of α-amylase and invertase activities, phenolic, flavonoid and alkaloid contents. Results: C. edulis extracts (CEE) had a higher scavenging potential on the 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), nitrite oxide (NO), 2, 2-azinobis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals and glucose scavenging with the IC50 varied between 41.95 and 36694.43 µg/ml depending on the solvent of extraction. The ethanol extract of C. edulis stem bark (CE EtOH) showed the highest polyphenolic (289.10 + 30.32), flavonoid (1.12 + 0.09) and alkaloids (18.47 + 0.16) content. All the tested extracts demonstrated a relative high inhibition potential against α-amylase and invertase digestive enzymes activities. Conclusion: This study suggests that CEE exhibited higher antioxidant potential and significant inhibition potential against digestive enzymes.

Keywords: Coula edulis, antioxidant, scavenging activity, amylase, invertase

Procedia PDF Downloads 342

Authors: M. Bouzid, A. Djadi, C. Aribi, A. Irekti, B. Bezzazi, F. Halouene

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The nature of materials structuring our health institutions promote the development of germs. The sustainability of nosocomial infections remains significant (12% and 15%). One of the major factors is the portland cement which is brittle and porous. As part of a national plan to fight nosocomial infections, led by the University Hospital of Blida, we opted for a composite coating, application by multilayer model, composed of epoxy-polyester resin as a binder and calcium carbonate as mineral fillers. The application of composite materials reinforce the wall coating of hospital units and eliminates the hospital infectious areas. The resistance to impact, chemicals, raising temperature and to a biologically active environment gives satisfactory results.

Keywords: nosocomial infection, microbial load, composite materials, portland cement

Procedia PDF Downloads 381

Authors: Ilma Ulfatul Janah, Ibnu Rizky Briwantara, Muhammad Afif

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The agricultural sector is one of the sectors that contribute to national development. The benefit of the agricultural sector can be felt directly by the majority of Indonesian people. Indonesia is one of the agricultural countries and most of the people working in the agricultural sector. Hence, the agricultural sector’s become the second sector which has contributed greatly to the growth of Gross Domestic Product (GDP) after the manufacture sector. Based on the National Medium Term Development Plan (RPJMN) from 2015 to 2019, one of the targets to be achieved by the Indonesian government is rice’s self-sufficient. Rice is the main food commodities which as most people in Indonesia, and it is making Indonesian government attempt self-sufficient in rice. Indonesia as an agricultural country becomes one of the countries that have a lower percentage of food security than other ASEAN countries. Rice self-sufficiency can be created through agricultural productivity and the availability of a market for the output. There are some problems still to be faced by the farmers such as farmer exchange rate is low. The low exchange rate of farmers showed that the level of the welfare’s Indonesian farmers is still low. The aims of this paper are to resolve problems related to food security and improve the welfare of the national rice farmers. The method by using materials obtained from the analysis of secondary data with the descriptive approach and conceptual framework. Integrated Farmers barn raising rice production is integrated and managed by the government coupled with the implementation of technology in the form of systems connected and accessible to farmers, namely 'SIBUNGTAN'.

Keywords: agriculture, self-sufficiency, technology, productivity

Procedia PDF Downloads 241

Authors: Nicola Rubino

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This paper presents an analysis of a group of commodity exporting countries' nominal exchange rate movements in relationship to the US dollar. Using a series of Unrestricted Self-exciting Threshold Autoregressive models (SETAR), we model and evaluate sixteen national CPI price differentials relative to the US dollar CPI. Out-of-sample forecast accuracy is evaluated through calculation of mean absolute error measures on the basis of two-hundred and fifty-three months rolling window forecasts and extended to three additional models, namely a logistic smooth transition regression (LSTAR), an additive non linear autoregressive model (AAR) and a simple linear Neural Network model (NNET). Our preliminary results confirm presence of some form of TAR non linearity in the majority of the countries analyzed, with a relatively higher goodness of fit, with respect to the linear AR(1) benchmark, in five countries out of sixteen considered. Although no model appears to statistically prevail over the other, our final out-of-sample forecast exercise shows that SETAR models tend to have quite poor relative forecasting performance, especially when compared to alternative non-linear specifications. Finally, by analyzing the implied half-lives of the > coefficients, our results confirms the presence, in the spirit of arbitrage band adjustment, of band convergence with an inner unit root behaviour in five of the sixteen countries analyzed.

Keywords: transition regression model, real exchange rate, nonlinearities, price differentials, PPP, commodity points

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Authors: Nguyen Viet Tan

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The Bahnar is one of 11 indigenous groups living in the Central Highlands of Vietnam. It is one among the four most popular groups in this area, including the Mnong who speak the same language of Mon Khmer family, while both groups of the Jrai and the Rhade belong to the Malayo-Polynesian language family. These groups once captured fertile plateaus, left their cultural and artistic heritage which affected the remaining small groups. Despite the difference in ethnic origins, these groups seem to share similar beliefs, customs and related folk arts after a very long time living beside each other. However, through an in-depth study, this paper points out the fact that the decorative patterns used by the Bahnar are different from the other ethnic groups, especially in color. Based on historical materials from the local museums and some studies in 1980s when all of the ethnic groups in this area had still lived in self-sufficient condition, this paper characterizes the traditional color scheme used by the Bahnar and identifies the difference in decorative motifs of this group compared to the others by pointing out they do not use green in their usual decorative patterns. Moreover, combined with some field surveys recently, through comparative analysis, it also discovers stylistic variations of these patterns in the process of cultural exchange with the other ethnic groups, both in and out of the region, in modern living conditions. This study helps to preserve and promote the traditional values and cultural identity of the Bahnar people in the Central Highlands of Vietnam, avoiding the fusion of styles among groups during the cultural exchange.

Keywords: Bahnar ethnic group, decorative patterns, the central highlands of Vietnam, the traditional color scheme

Procedia PDF Downloads 119

Authors: Shinji Kajiwara

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The spring-driven ball-type check valve is one of the most important components of hydraulic systems: it controls the position of the ball and prevents backward flow. To simplify the structure, the spring must be eliminated, and to accomplish this, the flow pattern and the behavior of the check ball in L-shaped pipe must be determined. In this paper, we present a full-scale model of a check ball made of acrylic resin, and we determine the relationship between the initial position of the ball, the position and diameter of the inflow port. The check flow rate increases in a standard center inflow model, and it is possible to greatly decrease the check-flow rate by shifting the inflow from the center.

Keywords: hydraulics, pipe flow, numerical simulation, flow visualization, check ball, L-shaped pipe

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Authors: Pradthana Sianglam, Wittaya Ngeontae

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A new approach for the fabrication of cadmium ion (Cd2+) sensor is demonstrated. The detection principle is based on the in-situ generation of cadmium sulfide quantum dots (CdS QDs) in the presence of chiral thiol containing compound and detection by the circular dichroism spectroscopy (CD). Basically, the generation of CdS QDs can be done in the presence of Cd2+, sulfide ion and suitable capping compounds. In addition, the strong CD signal can be recorded if the generated QDs possess chiral property (from chiral capping molecule). Thus, the degree of CD signal change depends on the number of the generated CdS QDs which can be related to the concentration of Cd2+ (excess of other components). In this work, we use the mixture of cysteamine (Cys) and L-Penicillamine (LPA) as the capping molecules. The strong CD signal can be observed when the solution contains sodium sulfide, Cys, LPA, and Cd2+. Moreover, the CD signal is linearly related to the concentration of Cd2+. This approach shows excellence selectivity towards the detection of Cd2+ when comparing to other cation. The proposed CD sensor provides low limit detection limits around 70 µM and can be used with real water samples with satisfactory results.

Keywords: circular dichroism sensor, quantum dots, enaniomer, in-situ generation, chemical sensor, heavy metal ion

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Authors: Anastasia Beketova, Emmanouil-George C. Tzanakakis, Ioannis G. Tzoutzas, Eleana Kontonasaki

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In restorative dentistry, yttria-stabilized zirconia (YSZ) nanoparticles can be applied as fillers to improve the mechanical properties of various resin-based materials. Using sol-gel based synthesis as simple and cost-effective method, nano-sized YSZ particles with high purity can be produced. The aim of this study was to synthesize YSZ nanoparticles by the Pechini sol-gel method at different temperatures and to investigate their composition, structure, and morphology. YSZ nanopowders were synthesized by the sol-gel method using zirconium oxychloride octahydrate (ZrOCl₂.8H₂O) and yttrium nitrate hexahydrate (Y(NO₃)₃.6H₂O) as precursors with the addition of acid chelating agents to control hydrolysis and gelation reactions. The obtained powders underwent TG_DTA analysis and were sintered at three different temperatures: 800, 1000, and 1200°C for 2 hours. Their composition and morphology were investigated by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy with associated with Energy Dispersive X-ray analyzer (SEM-EDX), Transmission Electron Microscopy (TEM) methods, and Dynamic Light Scattering (DLS). FTIR and XRD analysis showed the presence of pure tetragonal phase in the composition of nanopowders. By increasing the calcination temperature, the crystallinity of materials increased, reaching 47.2 nm for the YSZ1200 specimens. SEM analysis at high magnifications and DLS analysis showed submicron-sized particles with good dispersion and low agglomeration, which increased in size as the sintering temperature was elevated. From the TEM images of the YSZ1000 specimen, it can be seen that zirconia nanoparticles are uniform in size and shape and attain an average particle size of about 50 nm. The electron diffraction patterns clearly revealed ring patterns of polycrystalline tetragonal zirconia phase. Pure YSZ nanopowders have been successfully synthesized by the sol-gel method at different temperatures. Their size is small, and uniform, allowing their incorporation of dental luting resin cements to improve their mechanical properties and possibly enhance the bond strength of demanding dental ceramics such as zirconia to the tooth structure. This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme 'Human Resources Development, Education and Lifelong Learning 2014- 2020' in the context of the project 'Development of zirconia adhesion cements with stabilized zirconia nanoparticles: physicochemical properties and bond strength under aging conditions' (MIS 5047876).

Keywords: dental cements, nanoparticles, sol-gel, yttria-stabilized zirconia, YSZ

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Authors: Cecilia Espindola, Juan Carlos Palacios

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Flavonoids are a large group of natural compounds which are found in many fruits and vegetables. A subgroup of these called flavanones display a wide range of biological activities, and they also have an important physiological role in plants. The ionic liquid (ILs) are compounds consisting of an organic cation with an organic or inorganic anion. Due to its unique properties such as high electrical conductivity, wide temperature range of the liquid state, thermal and electrochemical stability, high ionic density and low volatility and flammability, are considered as ecological solvents in organic synthesis, catalysis, electrolytes in accumulators, and electrochemistry, non-volatile plasticizers, and chemical separation. It was synthesized ionic liquid IL 1-butyl-3-methylimidazolium bromide free-solvent and used as reaction medium for flavanones synthesis, under several reaction conditions of temperature, time and production. The obtained compounds were analyzed by melting point, elemental analysis, IR and UV-vis spectroscopy.

Keywords: 1-butyl-3-methylimidazolium bromide, flavonoids, free-solvent, IR spectroscopy

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Authors: Fan Wei, Tang Yipeng

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Knowledge sharing is of great value to organizational performance and innovation ability. However, the mainstream research has focused largely on the impact of knowledge sharing at the team level on individuals and teams. There is a lack of empirical studies on how employees interact in the exchange of knowledge and its effect on employees’ own creative performance. Based on communication accommodation theory and social exchange theory, this article explores the construction of an employee knowledge interaction mechanism under the moderating of social status and introduces the leader's creativity expectation as a moderating variable to explore its cross-level moderating effect on employee knowledge sharing and their own creative performance. An empirical test was conducted on 36 teaching and research teams in the two primary schools, and the results showed that: (1) Explicit/tacit knowledge of employees is positively correlated with acquisition of explicit/tacit knowledge; (2) Colleagues’ evaluations of employees’ social status play a moderating role between the employees’ explicit/tacit knowledge and the acquisition of explicit/tacit knowledge. (3) The leadership creativity expectation positively regulates the relationship between the employees' explicit knowledge acquisition and creative performance. This research helps to open the "black box" of the interpersonal interaction mechanism of knowledge sharing and also provides an important theoretical basis and practical guidance for organizational managers to effectively stimulate employee knowledge sharing and creative performance.

Keywords: knowledge sharing, knowledge interaction, social status, leadership creativity expectations, creative performance

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Authors: Philippe Castaing, Thomas Jollivet

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As a result of their advantages, i.e. recyclability, weld-ability, environmental compatibility, long (continuous) fiber thermoplastic composites (LFTPC) are increasingly used in many industrial sectors (mainly automotive and aeronautic) for structural applications. Indeed, in the next ten years, the environmental rules will put the pressure on the use of new structural materials like composites. In aerospace, more than 50% of the damage are due to stress impact and 85% of damage are repaired on the fuselage (fuselage skin panels and around doors). With the arrival of airplanes mainly of composite materials, replacement of sections or panels seems difficult economically speaking and repair becomes essential. The objective of the present study is to propose a solution of repair to prevent the replacement the damaged part in thermoplastic composites in order to recover the initial mechanical properties. The classification of impact damage is not so not easy : talking about low energy impact (less than 35 J) can be totally wrong when high speed or weak thicknesses as well as thermoplastic resins are considered. Crash and perforation with higher energy create important damages and the structures are replaced without repairing, so we just consider here damages due to impacts at low energy that are as follows for laminates : − Transverse cracking; − Delamination; − Fiber rupture. At low energy, the damages are barely visible but can nevertheless reduce significantly the mechanical strength of the part due to resin cracks while few fiber rupture is observed. The patch repair solution remains the standard one but may lead to the rupture of fibers and consequently creates more damages. That is the reason why we investigate the repair of thermoplastic composites impacted at low energy. Indeed, thermoplastic resins are interesting as they absorb impact energy through plastic strain. The methodology is as follows: - impact tests at low energy on thermoplastic composites; - identification of the damage by micrographic observations; - evaluation of the harmfulness of the damage; - repair by reconsolidation according to the extent of the damage ; -validation of the repair by mechanical characterization (compression). In this study, the impacts tests are performed at various levels of energy on thermoplastic composites (PA/C, PEEK/C and PPS/C woven 50/50 and unidirectional) to determine the level of impact energy creating damages in the resin without fiber rupture. We identify the extent of the damage by US inspection and micrographic observations in the plane part thickness. The samples were in addition characterized in compression to evaluate the loss of mechanical properties. Then the strategy of repair consists in reconsolidating the damaged parts by thermoforming, and after reconsolidation the laminates are characterized in compression for validation. To conclude, the study demonstrates the feasibility of the repair for low energy impact on thermoplastic composites as the samples recover their properties. At a first step of the study, the “repair” is made by reconsolidation on a thermoforming press but we could imagine a process in situ to reconsolidate the damaged parts.

Keywords: aerospace, automotive, composites, compression, damages, repair, structural applications, thermoplastic

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Authors: Fatin Fadhilah Hasib, Dewi Nuraini, Nisful Laila, Muhammad Madyan

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A big political event such as Cabinet reshuffle mostly can affect the stock price positively or negatively, depend on the perception of each investor and potential investor. This study aims to analyze the movement of the market and trading activities which respect to an event using event study method. This method is used to measure the movement of the stock exchange in which abnormal return can be obtained by investor related to the event. This study examines the differences of reaction on abnormal return and trading volume activity from the companies listed in the Jakarta Islamic Index (JII), before and after the announcement of the Cabinet Work Volume II on 27 July 2016. The study was conducted in observation of 21 days in total which consists of 10 days before the event and 10 days after the event. The method used in this study is event study with market adjusted model method that observes market reaction to the information of an announcement or publicity events. The Results from the study showed that there is no significant negative nor positive reaction at the abnormal return and abnormal trading before and after the announcement of the cabinet reshuffle. It is indicated by the results of statistical tests whose value not exceeds the level of significance. Stock exchange of the JII just reflects from the previous stock prices without reflecting the information regarding to the Cabinet reshuffle event. It can be concluded that the capital market is efficient with a weak form.

Keywords: abnormal return, abnormal trading volume activity, event study, political event

Procedia PDF Downloads 287

Authors: Thi Huong Vu, Vijay Jayasena, Zhongxiang Fang, Gary Dykes

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Carob kibble has recently received attention due to the presence of high level of polyphenol antioxidants. The capacity of microorganisms to improve antioxidant activities and total phenolics in carob kibble was investigated in the study. Two types of microorganisms including lactic acid bacteria Lactobacillus plantarum (L. plantarum) and yeast Saccharomyces cerevisiae (S. cerevisiae) were used in single and in their combination as starters. The total phenolic content was determined by the Folin–Ciocalteu method. Antioxidant activities were assessed scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The study found that S. cerevisiae alone considerably improved 55% total phenolics content at 15 h, while L. plantarum caused in a loss of 20% through the process. Antioxidant capacity of the yeast-fermented samples significantly increased by 43 % and 10 % in ABTS and DPPH assays, respectively. However, reduction of 13 % and 32 % inhibition were recorded in the carob treated with L. plantarum. In the combination of S. cerevisiae and L. plantarum (1:1), both total phenolic content and antioxidant activity of carob kibble were a similar trend as these of S. cerevisiae single, but a lower improvement. The antioxidant power of the extracts was linearly correlated to their total phenolic contents (R=0.75). The results suggested that S. cerevisiae alone was the better for enhancement of both total phenolic content and antioxidant activity in carob kibble using submerged fermentation. The efficiency of fermentation reached the highest at 15h. Thus submerged fermentation with S. cerevisiae offers a tool with simple and cost effective to further increase the bioactive potential of carob kibble, which is in use for food, cosmetic and pharmaceutical industries.

Keywords: antioxidant activity, carob kibble, lactobacillus plantarum, saccharomyces cerevisiae, total phenolics

Procedia PDF Downloads 278

Authors: Khaldoon G. Albitar, Hassan Y. Kikhia, Jin P. Zhang

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Since 2007, all companies listed on both Shanghai Stock Exchange and Shenzhen Stock Exchange are required to prepare their consolidated financial statements in accordance with International Financial Reporting Standards (IFRS). This study investigates the impact of adopting IFRS on accounting quality for a sample of listed on Chinese companies during the period 2003-2013 with sample of 10846 observations over a four-year period before and a five-year period after the adoption of IFRS. This study tests whether the level of earnings management is significantly lower after the adoption of IFRS, and reported earnings is more value relevant during the IFRS period by using the Ohlson model and Jones model, as modified by Dechow. The empirical results show that accounting quality improved with lower earnings management and higher value relevant after the adoption of IFRS in China. The current study contributes to the literature on IFRS adoption and earning quality in two ways. First, As most of the existing studies on earnings quality and IFRS have been conducted on data from the U.S and European countries, this study fills a gap in the existing literature by studying the effect of adoption of IFRS on earnings quality in an emerging market. Second, the findings of our study have important implications for policymakers, auditors, multinational firms, and users of financial reports. As the rapid growth of China's economy gains global recognition, the Chinese stock market is capturing the attention of international investor.

Keywords: international financial reporting standards (ifrs), accounting quality, earnings management, value relevance, china

Procedia PDF Downloads 326

Authors: Sameh S. Namnqani, Yaqoob Y. Abobakar, Ahmed M. Alsewehri, Khaled M. AlQethami

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The main objective of this research is to know the impact of the application of the electronic supply system on the performance of the supply department of health organizations. To reach this goal, the study adopted independent variables to measure the dependent variable (performance of the supply department), namely: integration with suppliers, integration with intermediaries and distributors and knowledge of supply size, inventory, and demand. The study used the descriptive method and was aided by the questionnaire tool that was distributed to a sample of workers in the Supply Chain Management Department of King Abdullah Medical City. After the statistical analysis, the results showed that: The 70 sample members strongly agree with the (electronic integration with suppliers) axis with a p-value of 0.001, especially with regard to the following: Opening formal and informal communication channels between management and suppliers (Mean 4.59) and exchanging information with suppliers with transparency and clarity (Mean 4.50). It also clarified that the sample members agree on the axis of (electronic integration with brokers and distributors) with a p-value of 0.001 and this is represented in the following elements: Exchange of information between management, brokers and distributors with transparency, clarity (Mean 4.18) , and finding a close cooperation relationship between management, brokers and distributors (Mean 4.13). The results also indicated that the respondents agreed to some extent on the axis (knowledge of the size of supply, stock, and demand) with a p-value of 0.001. It also indicated that the respondents strongly agree with the existence of a relationship between electronic procurement and (the performance of the procurement department in health organizations) with a p-value of 0.001, which is represented in the following: transparency and clarity in dealing with suppliers and intermediaries to prevent fraud and manipulation (Mean 4.50) and reduce the costs of supplying the needs of the health organization (Mean 4.50). From the results, the study recommended several recommendations, the most important of which are: that health organizations work to increase the level of information sharing between them and suppliers in order to achieve the implementation of electronic procurement in the supply management of health organizations. Attention to using electronic data interchange methods and using modern programs that make supply management able to exchange information with brokers and distributors to find out the volume of supply, inventory, and demand. To know the volume of supply, inventory, and demand, it recommended the application of scientific methods of supply for storage. Take advantage of information technology, for example, electronic data exchange techniques and documents, where it can help in contact with suppliers, brokers, and distributors, and know the volume of supply, inventory, and demand, which contributes to improving the performance of the supply department in health organizations.

Keywords: healthcare supply chain, performance, electronic system, ERP

Procedia PDF Downloads 129

Authors: Chen-Yu Chen, Wei-Mon Yan, Chi-Nan Lai, Jian-Hao Su

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The proton exchange membrane fuel cell (PEMFC) becomes more important as an alternative energy source recently. Maintaining proper water content in the membrane is one of the key requirements for optimizing the PEMFC performance. The planar membrane humidifier has the advantages of simple structure, low cost, low-pressure drop, light weight, reliable performance and good gas separability. Thus, it is a common external humidifier for PEMFCs. In this work, a planar membrane humidifier for kW-scale PEMFCs is developed successfully. The heat and mass transfer of humidifier is discussed, and its performance is analyzed in term of dew point approach temperature (DPAT), water vapor transfer rate (WVTR) and water recovery ratio (WRR). The DPAT of the humidifier with the counter flow approach reaches about 6°C under inlet dry air of 50°C and 60% RH and inlet humid air of 70°C and 100% RH. The rate of pressure loss of the humidifier is 5.0×10² Pa/min at the torque of 7 N-m, which reaches the standard of commercial planar membrane humidifiers. From the tests, it is found that increasing the air flow rate increases the WVTR. However, the DPAT and the WRR are not improved by increasing the WVTR as the air flow rate is higher than the optimal value. In addition, increasing the inlet temperature or the humidity of dry air decreases the WVTR and the WRR. Nevertheless, the DPAT is improved at elevated inlet temperatures or humidities of dry air. Furthermore, the performance of the humidifier with the counter flow approach is better than that with the parallel flow approach. The DPAT difference between the two flow approaches reaches up to 8 °C.

Keywords: heat and mass transfer, humidifier performance, PEM fuel cell, planar membrane humidifier

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Authors: Aleksander Ostrowski, Hugh J. Byrne, Roland Sanctuary

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Investigation of the polymer interphases is an emerging field nowadays. In many cases interphases determine the functionality of a system. There is a great demand for exploration of fundamental understanding of the interphases and elucidation of their formation, dimensions dependent on various influencing factors, change of functional properties, etc. The epoxy applied on porous glass penetrates its pores with an extent dependent on the pore size, temperature and epoxy components mixing ratio. Developed over the recent time challenging sample preparation procedure allowed to produce very smooth epoxy-porous glass cross-sections. In this study, Raman spectroscopy was used to investigate the epoxy-porous glass interphases. It allowed for chemical differentiation between different regions at the cross-section and determination of the degree of cure of epoxy system in the porous glass.

Keywords: interphases, Raman spectroscopy, epoxy, porous glass

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Authors: Leo Latasch, Mario Di Gennaro

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Introduction: The goal of this project was to increase the resilience of the population as well as rescue organizations to make both quality and time-related improvements in handling crises. A helper network was created for this purpose. Methods: Social questions regarding the structure and purpose of helper networks were considered - specifically with regard to helper motivation, the level of commitment and collaboration between populations and agencies. The exchange of information, the coordinated use of volunteers, and the distribution of available resources will be ensured through defined communication and cooperation routines. Helper smartphones will also be used provide a picture of the situation on the ground. Results: The helper network was established and deployed based on the RESIBES information technology system. It consists of a service platform, a web portal and a smartphone app. The service platform is the central element for collaboration between the various rescue organizations, as well as for persons, associations, and companies from the population offering voluntary aid. The platform was used for: Registering helpers and resources and then requesting and assigning it in case of a disaster. These services allow the population's resources to be organized. The service platform also allows for a secure data exchange between services and external systems. Conclusions: The social and technical work priorities have allowed us to cover a full cycle of advance structural work, gaining an overview, damage management, evaluation, and feedback on experiences. This cycle allows experiences gained while handling the crisis to feed back into the cycle and improve preparations and management strategies.

Keywords: coordination, disaster, resilience, volunteers

Procedia PDF Downloads 134

Authors: B. Yaman, G. Acikbas, N. Calis Acikbas

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Epoxy based materials have advantages in tribological applications due to their unique properties such as light weight, self-lubrication capacity and wear resistance. On the other hand, their usage is often limited by their low load bearing capacity and low thermal conductivity values. In this study, it is aimed to improve tribological and also mechanical properties of epoxy by reinforcing with ceramic based porcelain waste. It is well-known that the reuse or recycling of waste materials leads to reduction in production costs, ease of manufacturing, saving energy, etc. From this perspective, epoxy and epoxy matrix composites containing 60wt% porcelain waste with different particle size in the range of below 90µm and 150-250µm were fabricated, and the effect of filler particle size on the mechanical and tribological properties was investigated. The microstructural characterization was carried out by scanning electron microscopy (SEM), and phase analysis was determined by X-ray diffraction (XRD). The Archimedes principle was used to measure the density and porosity of the samples. The hardness values were measured using Shore-D hardness, and bending tests were performed. Microstructural investigations indicated that porcelain particles were homogeneously distributed and no agglomerations were encountered in the epoxy resin. Mechanical test results showed that the hardness and bending strength were increased with increasing particle size related to low porosity content and well embedding to the matrix. Tribological behavior of these composites was evaluated in terms of friction, wear rates and wear mechanisms by ball-on-disk contact with dry and rotational sliding at room temperature against WC ball with a diameter of 3mm. Wear tests were carried out at room temperature (23–25°C) with a humidity of 40 ± 5% under dry-sliding conditions. The contact radius of cycles was set to 5 mm at linear speed of 30 cm/s for the geometry used in this study. In all the experiments, 3N of constant test load was applied at a frequency of 8 Hz and prolonged to 400m wear distance. The friction coefficient of samples was recorded online by the variation in the tangential force. The steady-state CoFs were changed in between 0,29-0,32. The dimensions of the wear tracks (depth and width) were measured as two-dimensional profiles by a stylus profilometer. The wear volumes were calculated by integrating these 2D surface areas over the diameter. Specific wear rates were computed by dividing the wear volume by the applied load and sliding distance. According to the experimental results, the use of porcelain waste in the fabrication of epoxy resin composites can be suggested to be potential materials due to allowing improved mechanical and tribological properties and also providing reduction in production cost.

Keywords: epoxy composites, mechanical properties, porcelain waste, tribological properties

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Authors: Grmay Kassa Brhane, Hailemariam Siyum Mekonen

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This study was designed to identify the hydrogeochemical and anthropogenic processes controlling the evaluation of groundwater chemistry in the Ellala catchment which covers about 296.5 km2 areal extent. The chemical analysis revealed that the major ions in the groundwater are Ca2+, Mg2+, Na+, and K+ (cations) and HCO3-, PO43-, Cl-, NO3-, and SO42-(anions). Most of the groundwater samples (68.42%) revealed that the groundwater in the catchment is non-alkaline. In addition to the contribution of aquifer material, the solid materials and liquid wastes discharged from different sources can be the main sources of pH and EC in the groundwater. It is observed that the EC of the groundwater is fairly correlated with the DTS. This indicates that high mineralized water is more conductor than water with low concentration. The degree of salinity of the groundwater increases along the groundwater flow path from East to West; then, areas surrounding Mekelle City are highly saline due to the liquid and solid wastes discharged from the city and the industries. The groundwater facies in the catchment are predominated with calcium, magnesium, and bicarbonate which are labeled as Ca-Mg-HCO3 and Mg-Ca-HCO3. The main geochemical process controlling the evolution of the groundwater chemistry in the catchment is rock-water interaction, particularly carbonate dissolution. Due to the clay layer in the aquifer, the reverse is ion exchange. Non-significant silicate weathering and halite dissolution also contribute to the evolution of groundwater chemistry in the catchment. The groundwater in the catchment is dominated by the meteoritic origin although it needs further groundwater chemistry study with isotope dating analysis. The groundwater is under-saturated with calcite, dolomite, and aragonite minerals; hence, the more these minerals encounter the groundwater, the more the minerals dissolve. The main source of calcium and magnesium in groundwater is the dissolution of carbonate minerals (calcite and dolomite) since carbonate rocks are the dominant aquifer materials in the catchment. In addition to this, the weathering of dolerite rock is a possible source of magnesium ions. The relatively higher concentration of sodium over chloride indicates that the source of sodium-ion is reverse ion exchange and/or weathering of sodium-bearing materials, such as shale and dolerite rather than halite dissolution. High concentration of phosphate, nitrate, and chloride in the groundwater is the main anthropogenic source that needs treatment, quality control, and management in the catchment. From the Base Exchange Index Analysis, it is possible to understand that, in the catchment, the groundwater is dominated by the meteoritic origin, although it needs further groundwater chemistry study with isotope dating analysis.

Keywords: Ellala catchment, factor, chemistry, geochemical, groundwater

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Authors: Rosemary R. Carlton, Roxane Caron

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Almost three decades ago, bell hooks (1994) identified the classroom as “the most radical space of possibility in the academy”. A feminist scholar, educator, and activist, hooks urged educators to transgress the boundaries of what might be customary or considered acceptable in teaching, thus encouraging the pursuit of new ways of knowing and different strategies for sharing knowledge. This paper reflects upon a particular response to hooks’ still relevant call for transgression in teaching. Specifically, this paper reports on the design, implementation, and preliminary analysis of a social work course integrating active pedagogy and transnational exchange to encourage students’ critical thinking and autonomous learning in their development as social workers in a global context. The bachelor’s level course, Pratiques spécifiques: Projet international, was developed collaboratively across three francophone institutions of higher learning in Belgium, Canada, and France: the Haute École de Namur-Liège-Luxembourg (Hénallux); the Université de Montréal; and, the Institut d’enseignement supérieur et professionnel, l’IRTS Paris Île-de-France. The driving aims of the course are to promote autonomous learning and critical thinking through a lens of transnational understandings of social problems -competencies indispensable to students’ development as social workers. The course is offered to two paired cohorts, one addressing the subject of “migrations” (Canada/France) and the other the subject of “sexual exploitation” (Canada/Belgium). Through the adaptation of a critical pedagogy of problem-based learning, students are called upon to actively engage in acquiring and applying knowledge to respond to “real life” social issues relating to migration or sexual exploitation. At the conclusion of the course, each cohort of students is brought together for a week-long intensive period of transnational exchange either at the Université de Montréal in Canada or at Hénallux in Belgium. Extending the bounds of the classroom across international borders allows students novel opportunities to deepen and expand their understandings of issues relating to predefined social issues and to critically examine associated social work practices. The paper opens with a presentation of the social work course. Specifically, the authors will outline their adaptation of a pedagogy of problem-based learning integrating transnational exchange in the design and implementation of the course. Returning to hooks’ notion of transgression in teaching, the paper offers a preliminary analysis of how and with what effect the course provides opportunities to transgress hierarchical student-teacher relationships; transgress conventional modes of learning to explore diverse sources of knowledge and transgress the walls of the university to engage with and learn from local and global partners. The paper concludes with a consideration of the potential influence of such transgressions in teaching for students’ development of critical thinking in their practice of social work in global context.

Keywords: active learning, critical pedagogy, social work intervention, transnational learning

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Authors: Ngo Thi Thanh Mai, Nguyen Thu Ha, Frances Crawford

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The demand for developing international social work field education is on the rise. Global foreign universities have considered international collaboration and cross-cultural perspective as an essential part of their social work training curriculum. International placement program at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) has met the need of international social work students, as well as the institutions involved in achieving social work professional social work knowledge in the Vietnamese context. This program has also lead to a long-term collaboration between HNUE and several global institutions in developing social work education, research and practice skill. This paper focuses on the benefits and challenges of students who involved in the global placement programme at Faculty of Social Work (FSW), Hanoi National University of Education (HNUE) and content of international field education provided to the international students based on the experience of the authors. Study results indicated that the participants have opportunity them to explore a new culture and social work system abroad especially in the Vietnamese context. However, there are still difficulties that international students have to face during different phases of the exchange process such as language and communication barriers, cultural value differences, insufficient support and supervision during placement. Basing on these results, the authors intend to propose some recommendations to enhance the programme activities such as pre-departure orientation, support and supervision during placement, cultural exchange and follow-up activities.

Keywords: social work education, social work, international placement, field placement, Vietnam

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Authors: Jasneet Kaur, Swapandeep Singh Chimni

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The unfavorable use of metal-based catalysts that are often extortionate and toxic can be overcome by using small organic molecules known as organocatalysts. A variety of small organic molecules, including Brønsted/Lewis bases and acids, based on sulfonic acids, phosphoric acids, amines, phosphines or carbenes, Cinchona alkaloids, have been used as organocatalysts. One of the key reasons for using organocatalysis is their ability to be effectively removed from the final product in comparison to the metallic counterparts, which are exceedingly difficult to remove. The present investigation seeks to explore the catalytic nature of Cinchona alkaloids as an organocatalyst for enantioselective synthesis of 3-substituted-3-aminooxindole, which is known to exhibit a variety of biological activities and pharmacological activities. In this context, an organocatalytic asymmetric route for the synthesis of 3-aminooxindoles via reaction of isatin imine with α-acetoxy-β-ketoesters has been developed. The bifunctional Cinchona derived thiourea catalyzed the reaction of α-acetoxy-β-ketoesters derivatives with isatin imine to afford 3-substituted-aminooxindole derivatives in up to 93% yield, 95% enantiomeric excess and >20:1 diastereomeric ratio. The reaction was performed at room temperature for two hours using 10 mol% of catalyst, in the presence of 4Å molecular sieves in tetrahydrofuran as a solvent at ambient temperature. After the completion of the reaction, the pure product could be easily separated by using column chromatography using hexane and ethyl acetate as solvents. In conclusion, the catalytic potential of Cinchona derived chiral thiourea-tertiary amine catalyst was explored for an organocatalytic enantioselective Mannich reaction of β-ketoester derivatives with various isatin imine derivatives under mild conditions.

Keywords: asymmetric synthesis, aminooxindoles, enantioselective, isatin imine

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Authors: Syed Jawad Hussain Shahzad, Muhammad Zakaria, Mobeen Ur Rehman, Saniya Khaild

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This study examines the co-movement between the Pakistan, Indian, S&P 500 and Nikkei 225 stock markets using weekly data from 1998 to 2013. The time-frequency relationship between the selected stock markets is conducted by using measures of continuous wavelet power spectrum, cross-wavelet transform and cross (squared) wavelet coherency. The empirical evidence suggests strong dependence between Pakistan and Indian stock markets. The co-movement of Pakistani index with U.S and Japanese, the developed markets, varies over time and frequency where the long-run relationship is dominant. The results of cross wavelet and wavelet coherence analysis indicate moderate covariance and correlation between stock indexes and the markets are in phase (i.e. cyclical in nature) over varying durations. Pakistan stock market was lagging during the entire period in relation to Indian stock market, corresponding to the 8~32 and then 64~256 weeks scale. Similar findings are evident for S&P 500 and Nikkei 225 indexes, however, the relationship occurs during the later period of study. All three wavelet indicators suggest strong evidence of higher co-movement during 2008-09 global financial crises. The empirical analysis reveals a strong evidence that the portfolio diversification benefits vary across frequencies and time. This analysis is unique and have several practical implications for regional and international investors while assigning the optimal weightage of different assets in portfolio formulation.

Keywords: co-movement, Pakistan stock exchange, S&P 500, Nikkei 225, wavelet analysis

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Authors: Peter Thissen

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In this work, we report about the influence of the chemical potential of water on the carbonation reaction of wollastonite (CaSiO3) as model surface of cement and concrete. Total energy calculations based on density functional theory (DFT) combined with kinetic barrier predictions based on nudge elastic band (NEB) method show that the exposure of the water-free wollastonite surface to CO2 results in a barrier-less carbonation. CO2 reacts with the surface oxygen and forms carbonate (CO32-) complexes together with a major reconstruction of the surface. The reaction comes to a standstill after one carbonate monolayer has been formed. In case one water monolayer is covering the wollastonite surface, the carbonation is no more barrier-less, yet ending in a localized monolayer. Covered with multilayers of water, the thermodynamic ground state of the wollastonite completely changes due to a metal-proton exchange reaction (MPER, also called early stage hydration) and Ca2+ ions are partially removed from solid phase into the H2O/wollastonite interface. Mobile Ca2+ react again with CO2 and form carbonate complexes, ending in a delocalized layer. By means of high resolution time-of-flight secondary-ion mass-spectroscopy images (ToF-SIMS), we confirm that hydration can lead to a partially delocalization of Ca2+ ions on wollastonite surfaces. Finally, we evaluate the impact of our model surface results by means of Low Energy Ion Scattering (LEIS) spectroscopy combined with careful discussion about the competing reactions of carbonation vs. hydration.

Keywords: Calcium-silicate, carbonation, hydration, metal-proton exchange reaction

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Authors: G. Minak, D. Ghelli, A. Zucchelli

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This paper presents the results of an experimental characterization of a glass fibre-epoxy composite. The behavior of the traditional two-phase composite has been compared with the one of a new three-phase composite where the epoxy matrix was modified by addition of a 3% weight fraction of montmorillonite nano-particles. Two different types of nano-clays, Cloisite® 30B and RXG7000, produced by Southern Clay Products Inc., have been considered. Three-point bending tests, both monotonic and cyclic, were carried out. A strong reduction of the ultimate flexural strength upon nano-modification has been observed in quasi-static tests. Fatigue tests yielded a smaller strength loss. In both quasi-static and fatigue tests a more pronounced tendency to delamination has been noticed in three-phase composites, especially in the case of 30B nano-clay, with respect to the standard two-phase glass fiber composite.

Keywords: bending fatigue, epoxy resin, glass fiber, montmorillonite

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Authors: Zuzana Sedláková, Magda Kárászová, Jiří Vejražka, Lenka Morávková, Pavel Izák

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Membrane separations are mentioned frequently as a possibility for CO2 capture. Selectivity of ionic liquid membranes is strongly determined by different solubility of separated gases in ionic liquids. The solubility of separated gases usually varies over an order of magnitude, differently from diffusivity of gases in ionic liquids, which is usually of the same order of magnitude for different gases. The present work evaluates the selection of an appropriate ionic liquid for the selective membrane preparation based on the gas solubility in an ionic liquid. The current state of the art of CO2 capture patents and technologies based on the membrane separations was considered. An overview is given of the discussed transport mechanisms. Ionic liquids seem to be promising candidates thanks to their tunable properties, wide liquid range, reasonable thermal stability, and negligible vapor pressure. However, the uses of supported liquid membranes are limited by their relatively short lifetime from the industrial point of view. On the other hand, ionic liquids could overcome these problems due to their negligible vapor pressure and their tunable properties by adequate selection of the cation and anion.

Keywords: biogas upgrading, carbon dioxide separation, ionic liquid membrane, transport properties

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Authors: Haidy S. Ghali, Engy Serag, A. Samer Ezeldin

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Copper is an essential raw material used in the construction industry. During the year 2021 and the first half of 2022, the global market suffered from a significant fluctuation in copper raw material prices due to the aftermath of both the COVID-19 pandemic and the Russia-Ukraine war, which exposed its consumers to an unexpected financial risk. Thereto, this paper aims to develop two ANN-LSTM price prediction models, using Python, that can forecast the average monthly copper prices traded in the London Metal Exchange; the first model is a multivariate model that forecasts the copper price of the next 1-month and the second is a univariate model that predicts the copper prices of the upcoming three months. Historical data of average monthly London Metal Exchange copper prices are collected from January 2009 till July 2022, and potential external factors are identified and employed in the multivariate model. These factors lie under three main categories: energy prices and economic indicators of the three major exporting countries of copper, depending on the data availability. Before developing the LSTM models, the collected external parameters are analyzed with respect to the copper prices using correlation and multicollinearity tests in R software; then, the parameters are further screened to select the parameters that influence the copper prices. Then, the two LSTM models are developed, and the dataset is divided into training, validation, and testing sets. The results show that the performance of the 3-Month prediction model is better than the 1-Month prediction model, but still, both models can act as predicting tools for diverse economic situations.

Keywords: copper prices, prediction model, neural network, time series forecasting

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Authors: Saran Toure

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Complex shaped parts manufactured using out of autoclave prepreg vacuum bagging has a high quality finish. This is not only due to in the control of resin to fibre ratio in prepregs, but also to a reduction in fibre misalignment, slippage and stresses occurring within plies during compaction. In a bid to further reduce deformation modes and control failure modes, we carried experiments where, we introduced wetted fabrics within a prepreg plybook during compaction. Here are presented the results obtained from the vacuum bagging of a complex shaped part. The shape is that of a turbine fan blade with smooth curves all throughout ending with sharp edged angles. The quality of the final part made from this blade is compared to that of the same blade made from standard vacuum bagging process of prepregs, without introducing wetted fabrics.

Keywords: complex shaped part, prepregs, drapability, vacuum bagging

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Authors: Radka Králová, Libor Kvítek, Václav Ranc, Aleš Panáček, Radek Zbořil

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Surface–Enhanced Raman Scattering (SERS) is an optical spectroscopic technique with very good potential for sensitive detection of substances. In this research, active substrates with high enhancement were provided. Novel silver particles (nanostructures) with high roughened, flower–like morphology were prepared by reduction of cation complex [Ag(NH3)2]+ in presence of sodium borohydride as reducing agent and stabilized polyacrylic acid. The products were characterized by UV/VIS absorption spectrophotometry. Special shapes of silver particles were determined by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). Dispersions of this particle were put on fixed substrate to producing suitable layer for SERS. Adenine was applied as basic substance whose effect of enhancement on the layer of silver nanostructures was studied. By comparison with our work, the important influence of stabilizers, polyacrylic acid with various molecular weight and concentration, on the transfer of particles and formation of new structure was confirmed.

Keywords: metals, nanostructures, chemical reduction, Raman spectroscopy, optical properties

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