Search results for: polyvinyl alcohol fibers

Authors: Mohamed H. Gabr, Kiyoshi Uzawa

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The current study aims to investigate the effect of fillers with different geometries and sizes on the interfacial shear properties of PA6 composites with de-sized carbon fiber. The fillers which have been investigated are namely; nano-layer silicates (nanoclay), sub-micro aluminum titanium (ALTi) particles, and multiwall carbon nanotube (MWCNT). By means of X-ray photoelectron spectroscopy (XPS), epoxide group which defined as a sizing agent, has been removed. Sizing removal can reduce the acid parameter of carbon fibers surface promoting bonding strength at the fiber/matrix interface which is a desirable property for the carbon fiber composites. Microdroplet test showed that the interfacial shear strength (IFSS) has been enhanced with the addition of 10wt% ALTi by about 23% comparing with neat PA6. However, with including other types of fillers into PA6, the results did not show enhancement of IFSS.

Keywords: sub-micro particles, nano-composites, interfacial shear strength, polyamide 6

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Authors: Anuj Suhag, Rahul Dayal

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Aluminum matrix composites (AMCs) refer to the class of metal matrix composites that are lightweight but high performance aluminum centric material systems. The reinforcement in AMCs could be in the form of continuous/discontinuous fibers, whisker or particulates, in volume fractions. Properties of AMCs can be altered to the requirements of different industrial applications by suitable combinations of matrix, reinforcement and processing route. This work focuses on the fabrication of aluminum alloy (Al6061) matrix composites (AMCs) reinforced with 5 and 3 wt% Al2O3 particulates of 45µm using stir casting route. The aim of the present work is to investigate the effects of process parameters, determined by design of experiments, on microhardness, microstructure, Charpy impact strength, surface roughness and tensile properties of the AMC.

Keywords: aluminium matrix composite, Charpy impact strength test, composite materials, matrix, metal matrix composite, surface roughness, reinforcement

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Authors: Lawal Alkasim, Clement M. Gonah, Zainab S. Aliyu

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This work is focus on recovering silicon form photovoltaic cells and repurposing it toward the use in glass, ceramics or glass ceramics as it is made up of silicon material. Silicon is the main back-bone and responsible for the thermodynamic properties of glass, ceramics and glass ceramics materials. Antireflection silicon is soluble in hot alkali. Successfully the recovered material composed of silicon and silicon nitride of the A.R, with a small amount of silver, Aluminuim, lead & copper in the sunshine of crystalline/non-crystalline silicon solar cell. Aquaregia is used to remove the silver, Aluminium, lead & copper. The recovered material treated with hot alkali highly concentrated to produce sodium silicate, which is an alkali silicate glass (water glass). This type of glass is produced through chemical process, unlike other glasses that are produced through physical process of melting and non-crystalline solidification. It has showed a property of being alkali silicate glass from its solubility in water and insoluble in alcohol. The XRF analysis shows the presence of sodium silicate.

Keywords: unrecyclable solar PV, crystalline silicon, hot conc. alkali, sodium silicate

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Authors: V. Davaakhuu, D. Tserendagva, D. Amarsaikhan, T. Altanstetseg

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In this study we aimed to detect main risk factors for diabetes in Mongolia and obtain data we used survey modified questionnaire. Survey data were obtained from 634 valid nurses (day work nurses-317, shift work nurses-317). Participants who were pregnant, less than 20 years old and no check for fasting glucose level were excluded from the survey in order to determine the risk factors of diabetes. Our study result shows the main risk factors of diabetes were physical inactivity, overweight and obesity, alcohol and tobacco use and lack of vegetable and fruit consumption. Peripheral blood glucose level was normal in subjects with BMI 26.28 ± 0.56, but 20 % of the subjects with normal blood glucose level were obese. Blood glucose level was higher in subjects with BMI 28.63 ± 2.32 and 36 % of them were obese. According to our study results, 3.62% of the surveyed population were identified having no diabetes risk factors, 52.3% were at risk, 28.8% were in higher risk for diabetes by the WHO criteria. In general, the prevalence of blood glucose were especially higher in shift work nurses.

Keywords: day work nurses, shift work nurses, BMI, WHR

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Authors: F. Siahmed, A. Lounis, L. Faghi

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The aim of this work is to study mechanical properties of composites based on fiber natural. This material has attracted attention of the scientific community for its mechanical properties, its moderate cost and its specification as regards the protection of environment. In this study the loofah part of the family of the natural fiber has been used for these significant mechanical properties. The fiber has porous structure, which facilitates the impregnation of the resin through these pores. The matrix used in this study is the type of unsaturated polyester. This resin was chosen for its resistance to long term.The work involves: -The chemical treatment of the fibers of loofah by NaOH solution (5%) -The realization of the composite resin / fiber loofah; The preparation of samples for testing -The tensile tests and bending -The observation of facies rupture by scanning electron microscopy The results obtained allow us to observe that the values of Young's modulus and tensile strength in tension is high and open up real prospects. The improvement in mechanical properties has been obtained for the two-layer composite fiber with 7.5% (by weight).

Keywords: loofah fiber, mechanical properties, composite, loofah fiber resin

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Authors: P. Altay, G. Kartal, B. Kizilkaya, S. Kahraman, N. C. Gursoy

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Biopolishing is applied to remove the fuzz or pills on the fiber or fabric surface which will reduce its tendency to pill or fuzz after repetitive launderings. After biopolishing process, the fuzzes ripped by cellulase enzymes cannot be thoroughly removed from fabric surface, they remain on the fabric or fiber surface; accordingly disturb the user and lead to decrease in productivity of drying process. The main objective of this study is to develop a method for removing weakened fuzz fibers and surface pills from biofinished fabric surface before drying process. Fuzzes in the lattice structure of fabric were completely removed from the internal structure of the fabric by air blowing. The presence of fuzzes leads to problems with formation of pilling and faded appearance; the removal of fuzzes from the fabric results in reduced tendency to pill formation, cleaner, smoother and softer surface, improved handling properties of fabric with maintaining original color.

Keywords: biopolishing, fuzz fiber, weakened fiber, biofinished cotton fabric

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Authors: Vara Prasad Vemu

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The aim of the present work is to investigate the mechanical properties and water absorption capacity of carbon and basalt fibers mixed with matrix epoxy. At present, there is demand for nature friendly products. Basalt reinforced composites developed recently, and these mineral amorphous fibres are a valid alternative to carbon fibres for their lower cost and to glass fibres for their strength. The present paper describes briefly on basalt and carbon fibres (uni-directional) which are used as reinforcement materials for composites. The matrix epoxy (LY 556-HY 951) is taken into account to assess its influence on the evaluated parameters. In order to use reinforced composites for structural applications, it is necessary to perform a mechanical characterization. With this aim experiments like tensile strength, flexural strength, hardness and water absorption are performed. Later the mechanical properties obtained from experiments are compared with ANSYS software results.

Keywords: carbon fibre, basalt fibre, uni-directional, reinforcement, mechanical tests, water absorption test, ANSYS

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Authors: Ratna Dewi Kusumaningtyas, Prima Astuti Handayani, Arief Budiman

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Reactive Distillation (RD) is a multifunctional reactor which integrates chemical reaction with in situ separation to shift the equilibrium towards the product formation. Thus, it is suitable for equilibrium limited reaction such as esterification and transesterification to enhance the reaction conversion. In this work, the application of RD for high FFA oil esterification-transterification for biodiesel production using sulphuric acid catalyst has been studied. Crude Jatropha Oil with FFA content of 30.57% was utilized as the feedstock. Effects of the catalyst concentration and molar ratio of the alcohol to oils were also investigated. It was revealed that best result was obtained with sulphuric acid catalyst (reaction conversion of 94.71% and FFA content of 1.62%) at 60C, molar ratio of methanol to FFA of 30:1, and catalyst loading of 3%. After undergoing esterification reaction, jatropha oil was then transesterified to produce biodiesel. Transesterification reaction was performed in the presence of NaOH catalyst in RD column at 60C, molar ratio of methanol to oil of 6:1, and catalyst concentration of 1%. It demonstrated that biodiesel produced in this work agreed with the Indonesian National and ASTM standard of fuel.

Keywords: reactive distillation, biodiesel, esterification, transesterification

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Authors: C. Asha Poorna, N. S. Pradeep

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The biological function of lipase is to catalyze the hydrolysis of triacylglycerols to give free fatty acid, diacylglycerols, mono-acylglycerols and glycerol. They constitute the most important group of biocatalysts for biotechnological applications. The aim of the present study was to identify the lipolytic activity of Streptomyces sp. From soil sample collected from the sacred groves of southern Kerala. The culture conditions of the isolate were optimised and the enzyme was purified and characterised. The purification was attempted with acetone precipitation. The isolate observed to have high lipolytic activity and identified to be of Streptomyces strain. The purification was attempted with acetone precipitation. The purified enzyme observed to have an apparent molecular mass of ~60kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed maximum activity at 60oC and pH-8. The lipase showed tolerance towards different organic solvents like ethanol and methanol that are commonly used in transesterification reactions to displace alcohol from triglycerides contained in renewable resources to yield fatty acid alkyl esters known as biodiesel.

Keywords: lipase, Streptomyces, biodiesel, fatty acid, transesterification

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Authors: Esmaeil Biazar

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A nanofibrous PHBV nerve conduit has been used to evaluate its efficiency based on the promotion of nerve regeneration in rats. The designed conduits were investigated by physical, mechanical and microscopic analyses. The conduits were implanted into a 30-mm gap in the sciatic nerves of the rats. Four months after surgery, the regenerated nerves were evaluated by macroscopic assessments and histology. This polymeric conduit had sufficiently high mechanical properties to serve as a nerve guide. The results demonstrated that in the nanofibrous graft with cells, the sciatic nerve trunk had been reconstructed with restoration of nerve continuity and formatted nerve fibers with myelination. For the grafts especially the nanofibrous conduits with cells, muscle cells of gastrocnemius on the operated side were uniform in their size and structures. This study proves the feasibility of artificial conduit with Schwann cells for nerve regeneration by bridging a longer defect in a rat model.

Keywords: sciatic regeneration, Schwann cell, artificial conduit, nanofibrous PHBV, histological assessments

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Authors: Bambang Ariantara, Nandy Putra, Rangga Aji Pamungkas

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The development of electric vehicle batteries has resulted in very high energy density lithium-ion batteries. However, this progress is accompanied by the risk of thermal runaway, which can result in serious accidents. Heat pipes are heat exchangers that are suitable to be applied in electric vehicle battery thermal management for their lightweight, compact size and do not require external power supply. This paper aims to examine experimentally a flat plate loop heat pipe (FPLHP) performance as a heat exchanger in the thermal management system of the lithium-ion battery for electric vehicle application. The heat generation of the battery was simulated using a cartridge heater. Stainless steel screen mesh was used as the capillary wick. Distilled water, alcohol and acetone were used as working fluids with a filling ratio of 60%. It was found that acetone gives the best performance that produces the thermal resistance of 0.22 W/°C with 50 °C evaporator temperature at heat flux load of 1.61 W/cm2.

Keywords: electric vehicle, flat-plate loop heat pipe, lithium-ion battery, thermal management system

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Authors: Xitong Liu, Yutong Huang, Shu-Ching Yang

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The phenomena of hypergamous and hypogamous marriages have become popular due to the imbalanced sex ratio caused by Chinese social preference for sons. Our research explores the spillover effect of husbands' lifestyles on their wives' marital satisfaction in China. Both personal and spouse lifestyle elements are utilized to develop regression models to study husbands' spillover effects on women's marital satisfaction. With data from China Family Panel Study and Stata for analysis, we tested our hypothesis that both smoking and substance use by a spouse will negatively impact women's marital satisfaction. Our empirical findings suggest that substance use has negative implications on marriage satisfaction. In particular, husbands' substance use is more critical to wives' marriage satisfaction than wives' behaviours. Conversely, another behavior indicating bad habits, the number of times the spouse drank alcohol, had no significant effect on the wife's marital satisfaction. We concluded our investigation and provided future implications for scholars in the family economics field.

Keywords: Asian/Pacific Islander families, family economics, housework/division of labor, spillover

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Authors: Muhammad Ayoub, Abrar Inayat, Bhajan Lal, Sintayehu Mekuria Hailegiorgis

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Biodiesel which comes from pure renewable resources provide an alternative fuel option for future because of limited fossil fuel resources as well as environmental concerns. The transesterification of vegetable oils for biodiesel production is a promising process to overcome this future crises of energy. The use of heterogeneous catalysts greatly simplifies the technological process by facilitating the separation of the post-reaction mixture. The purpose of the present work was to examine a heterogeneous catalyst, in particular, Mg-Al modified K-10 clay, to produce methyl esters of palm oil. The prepared catalyst was well characterized by different latest techniques. In this study, the transesterification of palm oil with methanol was studied in a heterogeneous system in the presence of Mg-Al modified K-10 clay as solid base catalyst and then optimized these results with the help of Design of Experiments software. The results showed that methanol is the best alcohol for this reaction condition. The best results was achieved for optimization of biodiesel process. The maximum conversion of triglyceride (88%) was noted after 8 h of reaction at 60 ̊C, with a 6:1 molar ratio of methanol to palm oil and 3 wt % of prepared catalyst.

Keywords: palm oil, transestrefication, clay, biodiesel, mesoporous clay, K-10

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Authors: Mbadugha Esther Ifeoma

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Soybeans, like other legumes are rich in nutrients. However, the nutrient profile of soybeans differs in some important ways from most other legumes. Among other nutrients, soy is high in protein, carbohydrates, and fibers, is rich in vitamins, minerals and unsaturated fatty acids and is low in saturated fatty acids. Because of its high nutritional value, it has been rated to be equivalent to meats, eggs and milk. Soy has many health benefits including prevention of coronary heart disease, prevention of cancer growth, improvement of cognitive function, promotion of bone health, prevention of obesity, prevention of type II diabetes and promotion of growth of normal floras in the colon. Soybean consumption is also associated with some side effects which include allergy, flatulence and abdominal discomfort. Nurses/health care providers should therefore, educate clients on the precautionary measures to be taken in preparing soy food products in order to reduce to the barest minimum the side effects, while encouraging them to include soy as part of their daily meals for optimal health and vitality.

Keywords: health benefit, health education, nutritional benefit, soybeans

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Authors: Saad Ahmed, Sanjeev Khannaa

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Glass fiber reinforced polymers are widely used in structural systems as load-bearing elements at both high and low temperatures. This investigation presents the evaluation of glass fiber reinforced unsaturated polyurethane under harsh conditions of changing temperature and moisture content. This study Explores how these parameters affect the optical properties of the polymer matrix and the composite. Using the hand layup method, the polyurethane resin was modified by E-glass fibers (15 vol. %) to manufacture fiber-reinforced composite. This work includes the preparation of glass-like polyurethane resin sheets and estimates all light transmittance properties at high and very low temperatures and wet conditions. All-optical properties were retested to evaluate the level of improvement or failure. The results found that when comprising reinforced composite fiber to the unreinforced specimens, the reinforced composite shows a fair optical property at high temperatures and good performance at low temperatures.

Keywords: unsaturated polyurethane, extreme temperatures, light transmittance, haze number

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Authors: Jian Zheng, Jinfeng Yu, Xinhua Ni

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The limiting fracture stress predicting model of composite ceramics with symmetric triangle eutectic was established based on its special microscopic structure. The symmetric triangle eutectic is consisted of matrix, the strong constraint inter-phase and reinforced fiber inclusions which are 120 degrees uniform symmetrical distribution. Considering the conditions of the rupture of the cohesive bond between matrix and fibers in eutectic and the stress concentration effect at the fiber end, the intrinsic fracture stress of eutectic was obtained. Based on the biggest micro-damage strain in eutectic, defining the load function, the macro-damage fracture stress of symmetric triangle eutectic was determined by boundary conditions. Introducing the conception of critical zone, the theoretical limiting fracture stress forecasting model of composite ceramics was got, and the stress was related to the fiber size and fiber volume fraction in eutectic. The calculated results agreed with the experimental results in the literature.

Keywords: symmetric triangle eutectic, composite ceramics, limiting stress, intrinsic fracture stress

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Authors: A. Tuna, Y. Okumuş, A. T. Seyhan, H. Çelebi

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In this study, microfluidization was considered a promising approach to breaking up of carbonized chicken feather fibers (CCFFs) flocs to synthesizing epoxy suspensions containing (1 wt. %) CCFFs. For comparison, CCFF was also treated using sonication. The energy consumed to break up CCFFs in the ethanol was the same for both processes. CCFFs were found to be dispersed in ethanol in a significantly shorter time with the high shear processor. The CCFFs treated by both sonication and microfluidization were dispersed in epoxy by sonication. SEM examination revealed that CCFFs were broken up into smaller pieces using the high shear processor while being not agglomerated. Further, DSC, TMA, and DMA were systematically used to measure thermal properties of the resulting composites. A significant improvement was observed in the composites including CCFFs treated with microfluidization.

Keywords: carbonized chicken feather fiber (CCFF), modulated differential scanning calorimetry (MDSC), modulated thermomechanical analysis (MTMA), thermal properties

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Authors: Merve Tunay Çetin, Ali Kurşun, Erhan Çetin, Halil Aykul

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In this investigation an elastic stress analysis is carried out a woven steel fiber reinforced thermoplastic cantilever beam loaded uniformly at the upper surface. The composite beam material consists of low density polyethylene as a thermoplastic (LDFE, f.2.12) and woven steel fibers. Granules of the polyethylene is put into the moulds and they are heated up to 160°C by using electrical resistance. Subsequently, the material is held for 5min under 2.5 MPa at this temperature. The temperature is decreased to 30°C under 15 MPa pressure in 3 min. Closed form solution is found satisfying both the governing differential equation and boundary conditions. We investigated orientation angle effect on stress distribution of composite cantilever beams. The results show that orientation angle play an important role in determining the responses of a woven steel fiber reinforced thermoplastic cantilever beams and an optimal design of these structures.

Keywords: cantilever beam, elastic stress analysis, orientation angle, thermoplastic

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Authors: Mohammad S. Rouhi, Magdalena Juntikka

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Processing of polymer fiber composites has a remarkable influence on their mechanical performance. These mechanical properties are even more influenced when using recycled reinforcement. Therefore, we place particular attention on the evaluation of micromechanical models to estimate the mechanical properties and compare them against the experimental results of the manufactured composites. For the manufacturing process, an epoxy matrix and carbon fiber production cut-offs as reinforcing material are incorporated using a vacuum infusion process. In addition, continuous textile reinforcement in combination with the epoxy matrix is used as reference material to evaluate the kick-down in mechanical performance of the recycled composite. The experimental results show less degradation of the composite stiffness compared to the strength properties. Observations from the modeling also show the same trend as the error between the theoretical and experimental results is lower for stiffness comparisons than the strength calculations. Yet still, good mechanical performance for specific applications can be expected from these materials.

Keywords: composite recycling, carbon fibers, mechanical properties, micromechanics

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Authors: Beatrix Inah C. Mercado

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Bamboo shoots are the immature and edible culms from bamboos which contains high amount of dietary fibers. However, in spite of these functional properties of bamboo shoots it is still underutilized. Objectives: To develop bamboo shoot powder and incorporate it to biscuits as a source of dietary fiber and antioxidant. Materials and Methods: Bamboo shoot powder (BSP) was freeze-drying and grind and was incorporated to biscuits in 20% concentration. BSP and biscuits with BSP were analyzed for its proximate composition, dietary fiber, phytonutrients and antioxidant capacity. Results: BSP has 13.1 % moisture, 18.8% protein and 8% ash, 2.4g/100g total fat and 57.7% carbohydrate. BSP and biscuits with 20% BSP were good sources of dietary fiber containing 27.8g/100g and 7.1 g/100g, respectively. BSP is high in phytonutrient contents in terms of total polyphenols (1052mg gallic/100 g) and flavonoids (4046mg catechin/100g). Biscuits with BSP contained higher source of phytonutrients and antioxidant capacity as compared to biscuits without BSP. Sensory evaluation revealed that biscuits with BSP were more acceptable than biscuits without BSP. Conclusion: Bamboo shoots may be used as a potential functional ingredient in food products for broader application.

Keywords: bamboo shoots, phytonutrients, fiber, biscuit

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Authors: Erkihun Zelalem

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Ethiopian’s sheep population, estimated to be 25.5 million heads, is found widely distributed across the diverse agro-ecological zones of the country. In the past, there were many projects that done to improve production of meat, milk and productivity of sheep breed. However, no significance research has been done so far on production of wool fiber in Ethiopia which could be taken as a potential fiber next to cotton. The measurement of the sheep wool fiber physical properties is critically important, technical, commercial and certification point of view. A total of 24 sheep from different breeds (Menz, Tikur, Farta and Washera) were used in this study. Samples of fiber were analyzed using standard measurements for wool fiber length (WFL), mean fiber diameter (MFD), coefficient of variation of wool fiber diameter (FDCV), breaking strength, elongation, crimp, cleanness and moisture content. Based on the result all parameters shows that there is a great potential of getting of wool fiber from the skin of sheep and according to the standards of its property and grading system based on wool fiber fineness is medium to course. These types of fibers can be making carpets, blankets, rugs, coverings and other products.

Keywords: Fiber, Fineness, Carpet, Fleece, Raw Wool

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Authors: H. M. Wang, C. J. Chang

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As the threat of global climate change is more seriously, "net zero emissions by 2050" has become a common global goal. In order to reduce the consumption of petrochemical raw materials and reduce carbon emissions, low-carbon fiber materials have become key materials in the future global textile supply chain. This project uses polyolefin raw materials to modify through synthesis and amination to develop low-temperature dyeable polypropylene fibers, endow them with low-temperature dyeability and high color fastness that can be combined with acid dyes, and improve the problem of low coloring strength. The color fastness to washing can reach the requirement of commerce with 3.5 level or more. Therefore, we realize the entry of polypropylene fiber into the clothing textile supply chain, replace existing fiber raw materials, solve the problem of domestic chemical fiber, textile, and clothing industry's plight of no low-carbon alternative new material sources, and provide the textile industry with a solution to achieve the goal of net zero emissions in 2050.

Keywords: acid dyes, dyeing, low-temperature, polypropylene fiber

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Authors: Dagmara Malina, Katarzyna Bialik-Wąs, Klaudia Pluta

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The growing significance of transdermal systems, in which skin is a route for systemic drug delivery, has generated a considerable amount of data which has resulted in a deeper understanding of the mechanisms of transport across the skin in the context of the controlled and prolonged release of active substances. One of such solutions may be the use of carrier systems based on intelligent polymers with different physicochemical properties. In these systems, active substances, e.g. drugs, can be conjugated (attached), immobilized, or encapsulated in a polymer matrix that is sensitive to specific environmental conditions (e.g. pH or temperature changes). Intelligent polymers can be divided according to their sensitivity to specific environmental stimuli such as temperature, pH, light, electric, magnetic, sound, or electromagnetic fields. Materials & methods—The first stage of the presented research concerned the synthesis of pH-sensitive polymeric carriers by a radical polymerization reaction. Then, the selected active substance (hydrocortisone) was introduced into polymeric carriers. In a further stage, bio-hybrid sodium alginate/poly(vinyl alcohol) – SA/PVA-based hydrogel matrices modified with various carrier-drug systems were prepared with the chemical cross-linking method. The conducted research included the assessment of physicochemical properties of obtained materials i.e. degree of hydrogel swelling and degradation studies as a function of pH in distilled water and phosphate-buffered saline (PBS) at 37°C in time. The gel fraction represents the insoluble gel fraction as a result of inter-molecule cross-linking formation was also measured. Additionally, the chemical structure of obtained hydrogels was confirmed using FT-IR spectroscopic technique. The dynamic light scattering (DLS) technique was used for the analysis of the average particle size of polymer-carriers and carrier-drug systems. The nanocarriers morphology was observed using SEM microscopy. Results & Discussion—The analysis of the encapsulated polymeric carriers showed that it was possible to obtain the time-stable empty pH-sensitive carrier with an average size 479 nm and the encapsulated system containing hydrocortisone with an average 543 nm, which was introduced into hydrogel structure. Bio-hybrid hydrogel matrices are stable materials, and the presence of an additional component: pH-sensitive carrier – hydrocortisone system, does not reduce the degree of cross-linking of the matrix nor its swelling ability. Moreover, the results of swelling tests indicate that systems containing higher concentrations of the drug have a slightly higher sorption capacity in each of the media used. All analyzed materials show stable and statically changing swelling values in simulated body fluids - there is no sudden fluid uptake and no rapid release from the material. The analysis of FT-IR spectra confirms the chemical structure of the obtained bio-hybrid hydrogel matrices. In the case of modifications with a pH-sensitive carrier, a much more intense band can be observed in the 3200-3500 cm⁻¹ range, which most likely originates from the strong hydrogen interactions that occur between individual components.

Keywords: hydrogels, polymer nanocarriers, sodium alginate/poly(vinyl alcohol) matrices, wound dressings.

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Authors: Bikas Chandra Bhattarai

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Child labour is the serious issue all over the world. In Nepal, many children are working in different structured and unstructured sector. Metal fabrication is one of the sectors where many children are involved. The present study is carried out to focus on the overall socio-economic condition, psychological aspect, working environment condition and welfare of the child labour. Metal fabrication factories from Kirtipur, Chovar Area, Gongabu, Sitapaila and Sankhamul area of Kathmandu municipality were selected for the study. The structured questionnaire was prepared, and overall 55 children under age 16 were interviewed. Working in metal fabrication factory is risky job for children. The main reason behind child labour is poverty. The working environment in the metal fabrication factory was not found satisfactory. Children are exposed to various types of physical and chemical hazards. Factories are not paying proper attention to safety condition at the workplace. Large number of children is attracted towards smoking and drinking alcohol leading to unnecessary expense of their income. There should be the provision of regular health check up and insurance to the working children. Monitoring from the government level should be implemented for the betterment of working children.

Keywords: child labour, Kathmandu, Nepal, metal fabrication

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Authors: Shilpa Kulkarni, Sujata Patrikar

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A single-mode fiber directional coupler is modeled and simulated for its application in medical field. Various fiber devices based on evanescent field absorption, interferometry, couplers, resonators, tip coated fibers, etc, have been developed so far, suitable for medical application. This work focuses on the possibility of sensing by single mode fiber directional coupler. In the preset work, a fiber directional coupler is modeled to detect the changes taking place in the surrounding medium optoelectronically. In this work, waveguiding characteristics of the fiber are studied in depth. The sensor is modeled and simulated by finding photocurrent, sensitivity and detection limit by varying various parameters of the directional coupler. The device is optimized for the best possible output. It is found that the directional coupler shows measurable photocurrents and good sensitivity with coupling length in micrometers. It is thus a miniature device, hence, suitable for medical applications.

Keywords: single mode fiber directional coupler, modeling and simulation of fiber directional coupler sensor, biomolecular sensing, medical sensor device

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Authors: J. Shiri, A. Mansourizadeh, F. Faghih, H. Vaez

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In this study, porous polyvinylidene fluoride (PVDF) hollow fiber membranes are fabricated via a wet phase-inversion Process and used in the gas–liquid membrane contactor for physical CO2 absorption. Effect of different air gap on the structure and CO2 flux of the membrane was investigated. The hollow fibers were prepared using the wet spinning process using a dope solution containing PVDF/NMP/Licl (18%, 78%, 4%) at the extrusion rate of 4.5ml/min and air gaps of 0, 7, 15cm. Water was used as internal and external coagulants. Membranes were characterized using various techniques such as Field Emission Scanning Electron Microscopy (FESEM), Gas permeation test, Critical Water Entry Pressure (CEPw) to select the best membrane structure for Co2 absorption. The characterization results showed that the prepared membrane at which air gap possess small pore size with high surface porosity and wetting resistance, which are favorable for gas absorption application air gap increased, CEPw had a decrease, but the N2 permeation was decreased. Surface porosity and also Co2 absorption was increased.

Keywords: porous PVDF hollow fiber membrane, CO2 absorption, phase inversion, air gap

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Authors: Y. Shamas, S. Imanzadeh, A. Jarno, S. Taibi

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Silt-based construction material is acknowledged since forever and lately received the researchers’ attention more than before as being an ecological and economical alternative for typical cement-based concrete. Silt-based material is known for its worldwide availability, cheapness, and various applications. Some rules should be defined to obtain a standardized method for the use of raw earth as a modern construction material; but first, its mechanical properties should be precisely studied to better understand its behavior in order to find new aspects in making it a better competitor for the cement concrete that is high energy-demanding in terms of gray energy. Some researches were performed on the raw earth material to enhance its characteristics as strength and ductility for their importance and their wide use for various materials. Yet, many other mechanical properties can be used to study the mechanical behavior of raw earth materials such as Young’smodulus and toughness. Studies concerning the toughness of material were rarely conducted previously except for metals despite its significant role associated to the energy absorbed by the material under loading before fracturing. The purpose of this paper is to restate different toughness definitions used in the literature and propose a new definition.

Keywords: silt-based material, raw earth concrete, stress-strain curve, energy, toughness

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Authors: Chen Zhang, Fengxue Xin, Jianzhong He

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A unique Clostridium beijerinckii species strain BGS1 was obtained from grass land samples, which is capable of producing 8.43g/L butanol and 3.21 isopropanol from 60g/L glucose while generating 4.68g/L volatile fatty acids (VFAs) from 30g/L xylan. The concentration of isopropanol produced by culture BGS1 is ~15% higher than previously reported wild-type Clostridium beijerinckii under similar conditions. Compared to traditional Acetone-Butanol-Ethanol (ABE) fermentation species, culture BGS1 only generates negligible amount of ethanol and acetone, but produces butanol and isopropanol as biosolvent end-products which are pure alcohols and more economical than ABE. More importantly, culture BGS1 can consume acetone to produce isopropanol, e.g., 1.84g/L isopropanol from 0.81g/L acetone in 60g/L glucose medium containing 6.15g/L acetone. The analysis of BGS1 draft genome annotated by RAST server demonstrates that no ethanol production is caused by the lack of pyruvate decarboxylase gene – related to ethanol production. In addition, an alcohol dehydrogenase (adhe gene) was found in BGS1 which could be a potential gene responsible for isopropanol-generation. This is the first report on Isopropanol-Butanol (IB) fermentation by wild-type Clostridium strain and its application for isopropanol and butanol production.

Keywords: acetone conversion, butanol, clostridium, isopropanol

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Authors: Mahdi Fakoor, Hannaneh Manafi Farid

Abstract:

In order to predict the fracture behavior of cracked orthotropic materials under mixed-mode loading, well-known minimum strain energy density (SED) criterion is extended. The crack is subjected along the fibers at plane strain conditions. Despite the complicities to solve the nonlinear equations which are requirements of SED criterion, SED criterion for anisotropic materials is derived. In the present research, fracture limit curve of SED criterion is depicted by a numerical solution, hence the direction of crack growth is figured out by derived criterion, MSED. The validated MSED demonstrates the improvement in prediction of fracture behavior of the materials. Also, damaged factor that plays a crucial role in the fracture behavior of quasi-brittle materials is derived from this criterion and proved its dependency on mechanical properties and direction of crack growth.

Keywords: mixed-mode fracture, minimum strain energy density criterion, orthotropic materials, fracture limit curve, mode II critical stress intensity factor

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Authors: M. Aruna

Abstract:

Emphasis on the advancement of new materials and technology has been there for the past few decades. The global development towards using cheap and durable materials from renewable resources contributes to sustainable development. An experimental investigation of mechanical behaviour of sisal fiber-reinforced concrete is reported for making a suitable building material in terms of reinforcement. Fibre reinforced composite is one such material, which has reformed the concept of high strength. Sisal fibres are abundantly available in the hot areas. The sisal fiber has emerged as a reinforcing material for concretes, used in civil structures. In this work, properties such as hardness and tensile strength of sisal fibre reinforced cement composites with 6, 12, 18, and 24% by weight of sisal fibres were assessed. Sisal fiber reinforced cement composite slabs with long sisal fibers were manufactured using a cast hand layup technique. Mechanical response was measured under tension. The high energy absorption capacity of the developed composite system was reflected in high toughness values under tension respectively.

Keywords: sisal fibre, fiber-reinforced concrete, mechanical behaviour, composite materials

Procedia PDF Downloads 251