Search results for: glass fiber composite

Authors: A. Alshebani, Y. Swesi, S. Mrayed, F. Altaher, I. Musbah

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Cs-type nanocomposite zeolite membrane was successfully synthesized on an alumina ceramic hollow fibre with a mean outer diameter of 1.7 mm; cesium cationic exchange test was carried out inside test module with mean wall thickness of 230 μm and an average crossing pore size smaller than 0.2 μm. Separation factor of n-butane/H2 obtained indicate that a relatively high quality closed to 20. Maxwell-Stefan modeling provides an equivalent thickness lower than 1 µm. To compare the difference an application to CO2/N2 separation has been achieved, reaching separation factors close to (4,18) before and after cation exchange on H-zeolite membrane formed within the pores of a ceramic alumina substrate.

Keywords: MFI membrane, nanocomposite, ceramic hollow fibre, CO2, ion-exchange

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Authors: Noura El-Ahmady El-Naggar

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Among the antitumour drugs, bacterial enzyme L-asparaginase has been employed as the most effective chemotherapeutic agent in pediatric oncotherapy especially for acute lymphoblastic leukemia. Glutaminase free L-asparaginase producing actinomycetes were isolated from soil samples collected from Egypt. Among them, a potential culture, strain NEAE-119, was selected and identified on the basis of morphological, cultural, physiological and biochemical properties, together with 16S rDNA sequence as Streptomyces olivaceus NEAE-119 and sequencing product(1509 bp) was deposited in the GenBank database under accession number KJ200342. The optimization of different process parameters for L-asparaginase production by Streptomyces olivaceus NEAE-119 using Plackett–Burman experimental design and response surface methodology was carried out. Fifteen nutritional variables (temperature, pH, incubation time, inoculum size, inoculum age, agitation speed, dextrose, starch, L-asparagine, KNO3, yeast extract, K2HPO4, MgSO4.7H2O, NaCl and FeSO4. 7H2O) were screened using Plackett–Burman experimental design. The most positive significant independent variables affecting enzyme production (temperature, inoculum age and agitation speed) were further optimized by the central composite face-centered design -response surface methodology. As a result, a medium of the following formula is the optimum for producing an extracellular L-asparaginase in the culture filtrate of Streptomyces olivaceus NEAE-119: Dextrose 3g, starch 20g, L-asparagine 10g, KNO3 1g, K2HPO4 1g, MgSO4.7H2O 0.1g, NaCl 0.1g, pH 7, temperature 37°C, agitation speed 200 rpm/min, inoculum size 4%, v/v, inoculum age 72 h and fermentation period 5 days.

Keywords: Streptomyces olivaceus NEAE-119, glutaminase free L-asparaginase, production, Plackett-Burman design, central composite face-centered design, 16S rRNA, scanning electron microscope

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Authors: Ami Okabe, Daisuke Gondo, Akira Ogawa, Yasuhisa Hasegawa, Koichi Sato, Sadao Araki, Hideki Yamamoto

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Membrane separation draws attention as the energy-saving technology. Pervaporation (PV) uses hydrophobic ceramic membranes to separate organic compounds from industrial wastewaters. PV makes it possible to separate organic compounds from azeotropic mixtures and from aqueous solutions. For the PV separation of low concentrations of organics from aqueous solutions, hydrophobic ceramic membranes are expected to have high separation performance compared with that of conventional hydrophilic membranes. Membrane separation performance is evaluated based on the pervaporation separation index (PSI), which depends on both the separation factor and the permeate flux. Ingenuity is required to increase the PSI such that the permeate flux increases without reducing the separation factor or to increase the separation factor without reducing the flux. A thin separation layer without defects and pinholes is required. In addition, it is known that the flux can be increased without reducing the separation factor by reducing the diffusion resistance of the membrane support. In a previous study, we prepared hydrophobic silica membranes by a molecular templating sol−gel method using cetyltrimethylammonium bromide (CTAB) to form pores suitable for permitting the passage of organic compounds through the membrane. We separated low-concentration organics from aqueous solutions by PV using these membranes. In the present study, hydrophobic silica membranes were prepared on a porous alumina hollow fiber support that is thinner than the previously used alumina support. Ethyl acetate (EA) is used in large industrial quantities, so it was selected as the organic substance to be separated. Hydrophobic silica membranes were prepared by dip-coating porous alumina supports with a -alumina interlayer into a silica sol containing CTAB and vinyltrimethoxysilane (VTMS) as the silica precursor. Membrane thickness increases with the lifting speed of the sol in the dip-coating process. Different thicknesses of the γ-alumina layer were prepared by dip-coating the support into a boehmite sol at different lifting speeds (0.5, 1, 3, and 5 mm s-1). Silica layers were subsequently formed by dip-coating using an immersion time of 60 s and lifting speed of 1 mm s-1. PV measurements of the EA (5 wt.%)/water system were carried out using VTMS hydrophobic silica membranes prepared on -alumina layers of different thicknesses. Water and EA flux showed substantially constant value despite of the change of the lifting speed to form the γ-alumina interlayer. All prepared hydrophobic silica membranes showed the higher PSI compared with the hydrophobic membranes using the previous alumina support of hollow fiber.

Keywords: membrane separation, pervaporation, hydrophobic, silica

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Authors: Gilbert O. Osayemwenre, Meyer L. Edson

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Ethylene vinyl acetate (EVA) encapsulation degradation affects the performance of photovoltaic (PV) module. Hotspot formation causes the EVA encapsulation to undergo photothermal deterioration and molecular breakdown by UV radiation. This leads to diffusion of chemical particles into other layers. During outdoor deployment, the EVA encapsulation in the affect region loses its adhesive strength, when this happen the affected region layer undergoes rapid delamination. The presence of photo-thermal degradation is detrimental to PV modules as it causes both optical and thermal degradation. Also, it enables the encapsulant to be more susceptible to chemicals substance and moisture. Our findings show a high concentration of Sodium, Phosphorus and Aluminium which originate from the glass substrate, cell emitter and back contact respectively.

Keywords: ethylene vinyl acetate (EVA), encapsulation, photo-thermal degradation, thermogravimetric analysis (TGA), scanning probe microscope (SPM)

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Authors: Zellagui Rahima, Chaumont Denis, Boughelout Abderrahman, Adnane Mohamed

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Thin films of CdxZn1-xS were deposed by chemical bath deposition on glass substrates for photovoltaic applications. The thin films CdZnS were synthesized by chemical bath (CBD) with different deposition protocols for optimized the parameter of deposition as the temperature, time of deposition, concentrations of ion and pH. Surface morphology, optical and chemical composition properties of thin film CdZnS were investigated by SEM, EDAX, spectrophotometer. The transmittance is 80% in visible region 300 nm – 1000 nm; it has been observed in that films the grain size is between 50nm and 100nm measured by SEM image and we also note that the shape of particle is changing with the change in concentration. This result favors of application these films in solar cells; the chemical analysis with EDAX gives information about the presence of Cd, Zn and S elements and investigates the stoichiometry.

Keywords: thin film, solar cells, transmition, cdzns

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Authors: Claudia Cabezas-Zabala, Jairo Lindarte-Artunduaga, Carlos Mario Zuluaga-Dominguez

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Amaranth is an emerging pseudocereal rich in such essential nutrients as protein and dietary fiber, which was employed as an ingredient in the formulation of crackers to evaluate the rheological performance and sensory acceptability of the obtained food. A completely randomized factorial design was used with two factors: (A) ratio of wheat and amaranth flour used in the preparation of the dough, in proportion 90:10 and 80:20 (% w/w) and (B) two levels of inulin addition of 8.4% and 16.7 %, having two control doughs made from amaranth and wheat flour, respectively. Initially, the functional properties of the formulations mentioned were measured, showing no significant differences in the water absorption capacity (WAC) and swelling power (SP), having mean values between 1.66 and 1.81 g/g for WAC and between 1.75 and 1.86 g/g for SP, respectively. The amaranth flour had the highest water holding capacity (WHR) of 8.41 ± 0.15 g/g and emulsifying activity (EA) of 74.63 ± 1.89 g/g. Moreover, the rheological behavior, measured through the use of farinograph, extensograph, Mixolab, and falling index, showed that the formulation containing 20% of amaranth flour and 7.16% of inulin had a rheological behavior similar to the control produced exclusively with wheat flour, being the former, the one selected for the preparation of crackers. For this formulation, the farinograph showed a mixing tolerance index of 11 UB, indicating a strong and cohesive dough; likewise, the Mixolab showed dough reaches stability at 6.47 min, indicating a good resistance to mixing. On the other hand, the extensograph exhibited a dough resistance of 637 UB, as well as extensibility of 13.4 mm, which corresponds to a strong dough capable of resisting the laminate. Finally, the falling index was 318 s, which indicates the crumb will retain enough air to enhance the crispness of a characteristic cracker. Finally, a sensory consumer test did not show significant differences in the evaluation of aroma between the control and the selected formulation, while this latter had a significantly lower rating in flavor. However, a purchase intention of 70 % was observed among the population surveyed. The results obtained in this work give perspectives for the industrial use of amaranth in baked goods. Additionally, amaranth has been a product typically linked to indigenous populations in the Andean South American countries; therefore, the search for diversification and alternatives of use for this pseudocereal has an impact on the social and economic conditions of such communities. The technological versatility and nutritional quality of amaranth is an advantage for consumers, favoring the consumption of healthy products with important contributions of dietary fiber and protein.

Keywords: amaranth, crackers, rheology, pseudocereals, kneaded products

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Authors: Andrey V. Timofeev, Dmitry V. Egorov

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This paper presents development results of usage of C-OTDR monitoring systems for rail traffic management. The C-OTDR method is based on vibrosensitive properties of optical fibers. Analysis of Rayleigh backscattering radiation parameters changes which take place due to microscopic seismoacoustic impacts on the optical fiber allows to determine seismoacoustic emission source positions and to identify their types. This approach proved successful for rail traffic management (moving block system, weigh- in-motion system etc).

Keywords: C-OTDR systems, moving block-sections, rail traffic management, Rayleigh backscattering, weigh-in-motion

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Authors: Karan Modi, Rajesh Kumar, Jyoti Katiyar, Shreya Thusoo

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This paper presents Finite Element Method (FEM) for analyzing the internal responses generated in thin rectangular plates with various edge conditions and rigidity conditions. Comparison has been made between the FEM (ANSYS software) results for displacement, stresses and moments generated with and without the consideration of hole in plate and different aspect ratios. In the end comparison for responses in plain and composite square plates has been studied.

Keywords: ANSYS, finite element method, plates, static analysis

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Authors: Leila Graini

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In this paper, we demonstrate basic all-optical functions for 2R regeneration (Re-amplification and Re-shaping) based on self-similar spectral broadening in low normal dispersion and highly nonlinear fiber (ND-HNLF) to regenerate the signal through optical filtering including the transfer function characteristics, and output extinction ratio. Our approach of all-optical 2R regeneration is based on those of Mamyshev. The numerical study reveals the self-similar spectral broadening very effective for 2R all-optical regeneration; the proposed design presents high stability compared to a conventional regenerator using SPM broadening with reduction of the intensity fluctuations and improvement of the extinction ratio.

Keywords: all-optical function, 2R optical regeneration, self-similar broadening, Mamyshev regenerator

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Authors: Bassam M. Abunahel, Nurul Zahirah Noor Azman, Munirah Jamil

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The effect of needle diameter on the morphological structure of electrospun n-Bi₂O₃/epoxy-PVA nanofibers has been investigated using three different types of needle diameters. The results were observed and investigated using two techniques of scanning electron microscope (SEM). The first technique is backscattered SEM while the second is secondary electron SEM. The results demonstrate that there is a correlation between the needle diameter and the morphology of electrospun nanofibers. As the internal needle diameter decreases, the average nanofiber diameter decreases and the fibers get thinner and smoother without agglomeration or beads formation. Moreover, with small needle diameter the nanofibrous porosity get larger compared with large needle diameter.

Keywords: needle diameter, fiber diameter, porosity, agglomeration

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Authors: Renée M. Ripken, Johannes G. E. Gardeniers, Séverine Le Gac

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Controlling the multiphase behavior of aqueous biomass mixtures is essential when working in the biomass conversion industry. Here, the vapor/liquid equilibria (VLE) of ethylene glycol, glycerol, and xylitol were studied for temperatures between 25 and 200 °C and pressures of 1 to 10 bar. These experiments were performed in a microfluidic platform, which exhibits excellent heat transfer properties so that equilibrium is reached fast. Firstly, the saturated vapor pressure as a function of the temperature and the substrate mole fraction of the substrate was calculated using AspenPlus with a Redlich-Kwong-Soave Boston-Mathias (RKS-BM) model. Secondly, we developed a high-pressure and high-temperature microfluidic set-up for experimental validation. Furthermore, we have studied the multiphase flow pattern that occurs after the saturation temperature was achieved. A glass-silicon microfluidic device containing a 0.4 or 0.2 m long meandering channel with a depth of 250 μm and a width of 250 or 500 μm was fabricated using standard microfabrication techniques. This device was placed in a dedicated chip-holder, which includes a ceramic heater on the silicon side. The temperature was controlled and monitored by three K-type thermocouples: two were located between the heater and the silicon substrate, one to set the temperature and one to measure it, and the third one was placed in a 300 μm wide and 450 μm deep groove on the glass side to determine the heat loss over the silicon. An adjustable back pressure regulator and a pressure meter were added to control and evaluate the pressure during the experiment. Aqueous biomass solutions (10 wt%) were pumped at a flow rate of 10 μL/min using a syringe pump, and the temperature was slowly increased until the theoretical saturation temperature for the pre-set pressure was reached. First and surprisingly, a significant difference was observed between our theoretical saturation temperature and the experimental results. The experimental values were 10’s of degrees higher than the calculated ones and, in some cases, saturation could not be achieved. This discrepancy can be explained in different ways. Firstly, the pressure in the microchannel is locally higher due to both the thermal expansion of the liquid and the Laplace pressure that has to be overcome before a gas bubble can be formed. Secondly, superheating effects are likely to be present. Next, once saturation was reached, the flow pattern of the gas/liquid multiphase system was recorded. In our device, the point of nucleation can be controlled by taking advantage of the pressure drop across the channel and the accurate control of the temperature. Specifically, a higher temperature resulted in nucleation further upstream in the channel. As the void fraction increases downstream, the flow regime changes along the channel from bubbly flow to Taylor flow and later to annular flow. All three flow regimes were observed simultaneously. The findings of this study are key for the development and optimization of a microreactor for hydrogen production from biomass.

Keywords: biomass conversion, high pressure and high temperature microfluidics, multiphase, phase diagrams, superheating

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Authors: T. Schilirò, S. Bonetta, S. Bonetta, E. Ceretti, D. Feretti, I. Zerbini, V. Romanazzi, S. Levorato, T. Salvatori, S. Vannini, M. Verani, C. Pignata, F. Bagordo, G. Gilli, S. Bonizzoni, A. Bonetti, E. Carraro, U. Gelatti

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Air pollution is one of the most important worldwide health concern. In the last years, in both the US and Europe, new directives and regulations supporting more restrictive pollution limits were published. However, the early effects of air pollution occur, especially for the urban population. Several epidemiological and toxicological studies have documented the remarkable effect of particulate matter (PM) in increasing morbidity and mortality for cardiovascular disease, lung cancer and natural cause mortality. The finest fractions of PM (PM with aerodynamic diameter <2.5 µm and less) play a major role in causing chronic diseases. The International Agency for Research on Cancer (IARC) has recently classified air pollution and fine PM as carcinogenic to human (1 Group). The structure and composition of PM influence the biological properties of particles. The chemical composition varies with season and region of sampling, photochemical-meteorological conditions and sources of emissions. The aim of the MAPEC (Monitoring Air Pollution Effects on Children for supporting public health policy) study is to evaluate the associations between air pollution and biomarkers of early biological effects in oral mucosa cells of 6-8 year old children recruited from first grade schools. The study was performed in five Italian towns (Brescia, Torino, Lecce, Perugia and Pisa) characterized by different levels of airborne PM (PM10 annual average from 44 µg/m3 measured in Torino to 20 µg/m3 measured in Lecce). Two to five schools for each town were chosen to evaluate the variability of pollution within the same town. Child exposure to urban air pollution was evaluated by collecting ultrafine PM (PM0.5) in the school area, on the same day of biological sampling. PM samples were collected for 72h using a high-volume gravimetric air sampler and glass fiber filters in two different seasons (winter and spring). Gravimetric analysis of the collected filters was performed; PM0.5 organic extracts were chemically analyzed (PAH, Nitro-PAH) and tested on A549 by the Comet assay and Micronucleus test and on Salmonella strains (TA100, TA98, TA98NR and YG1021) by Ames test. Results showed that PM0.5 represents a high variable PM10 percentage (range 19.6-63%). PM10 concentration were generally lower than 50µg/m3 (EU daily limit). All PM0.5 extracts showed a mutagenic effect with TA98 strain (net revertant/m3 range 0.3-1.5) and suggested the presence of indirect mutagens, while lower effect was observed with TA100 strain. The results with the TA98NR and YG1021 strains showed the presence of nitroaromatic compounds as confirmed by the chemical analysis. No genotoxic or oxidative effect of PM0.5 extracts was observed using the comet assay (with/without Fpg enzyme) and micronucleus test except for some sporadic samples. The low biological effect observed could be related to the low level of air pollution observed in this winter sampling associated to a high atmospheric instability. For a greater understanding of the relationship between PM size, composition and biological effects the results obtained in this study suggest to investigate the biological effect of the other PM fractions and in particular of the PM0.5-1 fraction.

Keywords: airborne PM, ames test, comet assay, micronucleus test

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Authors: Fangying Wang, Zhang Sanming, Ni Qian

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In recent years, more and more personalized sound absorbing materials have entered the Chinese room acoustical decoration market. The acoustic performance of three kinds of personalized sound-absorbing materials: Flame-retardant Flax Fiber Sound-absorbing Cotton, Eco-Friendly Sand Acoustic Panel and Transparent Micro-perforated Panel (Film) are tested by Reverberation Room Method. The sound absorption characteristic curves show that their performance match for or even exceed the traditional sound absorbing material. Through the application in the actual projects, these personalized sound-absorbing materials also proved their sound absorption ability and unique decorative effect.

Keywords: acoustic performance, application prospect personalized sound-absorbing materials

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Authors: Vadim V. Zefirov, Victor E. Sizov, Marina A. Pigaleva, Igor V. Elmanovich, Mikhail S. Kondratenko, Marat O. Gallyamov

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This work presents a novel method for treating porous hydrophobic polyolefin membranes using supercritical carbon dioxide that allows usage of the modified membrane in redox flow batteries with an aqueous electrolyte. Polyolefin membranes are well known and widely used, however, they cannot be used as separators in redox flow batteries with an aqueous electrolyte since they have insufficient wettability, and therefore do not provide sufficient proton conductivity. The main aim of the presented work was the development of hydrophilic composites based on cheap membranes and precursors. Supercritical fluid was used as a medium for the deposition of the hydrophilic phase on the hydrophobic surface of the membrane. Due to the absence of negative capillary effects in a supercritical medium, a homogeneous composite is obtained as a result of synthesis. The in-situ synthesized silicon oxide nanoparticles and the chitosan polymer layer act as the hydrophilic phase and not only increase the affinity of the membrane towards the electrolyte, but also reduce the pore size of the polymer matrix, which positively affects the ion selectivity of the membrane. The composite material obtained as a result of synthesis has enhanced hydrophilic properties and is capable of providing proton conductivity in redox flow batteries. The morphology of the obtained composites was characterized by electron microscopy. To analyze the phase composition, infrared spectroscopy was used. The hydrophilic properties were studied by water contact angle measurements. In addition, the proton conductivity and ion selectivity of the obtained samples were studied, and tests in real redox flow batteries were performed. As a result, modified membrane was characterised in detail and moreover it was shown that modified cheap polyolefin membranes have pronounced proton conductivity and high ion selectivity, so their performance in a real redox flow battery approaches expensive commercial analogues, reaching 70% of energy efficiency.

Keywords: carbon dioxide, chitosan, polymer membrane, redox flow batteries, silica nanoparticles, supercritical fluid

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Authors: Yavuz Yardim

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FRP systems have been largely used to improve the performance of structural members, due to their high strength to weight ratio and corrosion resistance. Application of this strengthening procedure in circular columns has resulted quite beneficial in increasing their seismic and axial capacity. Whereas in the rectangular ones, strength enhancement was considerably less due to stress concentration in the corner. In this work three anchorage configurations are tested for their efficiency in increasing the uniformity of confinement pressure in the CFRP strengthened non-circular sections. There is a slight increase in the axial strength of specimens as a general trend. More specifically fan anchorage reached an increase of 17.5% compared to the unanchored specimens. The study shows that uniformity of confining pressure has increased by adding anchorage.

Keywords: rectangular columns, FRP, confinement, anchorage

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Authors: A. Attaf A., I. Bouhaf Kharkhachi

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Spray ultrasonic deposition technique of tin disulfide (SnS2) thin films know wide application due to their adequate physicochemical properties for microelectronic applications and especially for solar cells. SnS2 film was deposited by spray ultrasonic technique, on pretreated glass substrates at well-determined conditions.The effect of SnS2 concentration on different optical properties of SnS2 Thin films, such us MEB, XRD, and UV spectroscopy visible spectrum was investigated. MEB characterization technique shows that the morphology of this films is uniform, compact and granular. x-ray diffraction study detects the best growth crystallinity in hexagonal structure with preferential plan (001). The results of UV spectroscopy visible spectrum show that films deposited at 0.1 mol/l is large transmittance greater than 25% in the visible region.The band gap energy is 2.54 Ev for molarity 0.1 mol/l.

Keywords: MEB, thin disulfide, thin films, ultrasonic spray, X-Ray diffraction, UV spectroscopy visible

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Authors: Nadia Noor, Farida Faisal

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Horizontal hostility has been identified as a special type of workplace violence and refers to the aggressive behavior inflicted by women towards other women due to gender issues or towards minority group members due to minority issues. Many women, while they want eagerly to succeed and invest invigorated efforts to achieve success, harbor negative feelings for other women to succeed in their career. This phenomenon has been known as Horizontal Violence, Horizontal Hostility, Lateral Violence, Indirect Aggression, or The Tall Poppy Syndrome in Australian culture. Tall Poppy is referred to as a visibly successful individual who attracts envy or hostility due to distinctive characteristics. Therefore, horizontal hostility provides theoretical foundation to examine fierce competition among females than males for their limited access to top level management positions. In Pakistan, gender discrimination persists due to male dominance in the society and women do not enjoy basic equality rights in all aspects of life. They are oppressed at social and organizational level. As Government has been trying to enhance women participation through providing more employment opportunities, provision of peaceful workplace is mandatory that will enable aspiring females to achieve objectives of career success. This research study will help to understand antecedents, dimensions and outcomes of horizontal hostility that hinder career success of competitive females. The present paper is a review paper and various forms of horizontal hostility have been discussed in detail. Different psychological and organizational level drivers of horizontal hostility have been explored through literature. Psychological drivers include oppression, lack of empowerment, learned helplessness and low self-esteem. Organizational level drivers include sticky floor, glass ceiling, toxic work environment and leadership role. Horizontal hostility among working women results in psychological and physical outcomes including stress, low motivation, poor job performance and intention to leave. The study recommends provision of healthy and peaceful work environment that will enable competent women to achieve objectives of career success. In this regard, concrete actions and effective steps are required to promote gender equality at social and organizational level. The need is to ensure the enforcement of legal frameworks by government agencies in order to provide healthy working environment to women by reducing harassment and violence against them. Organizations must eradicate drivers of horizontal hostility and provide women peaceful work environment. In order to develop coping skills, training and mentoring must be provided to them.

Keywords: gender discrimination, glass ceiling, horizontal hostility, oppression

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Authors: Sudhir Kumar Sharma, Abiy D. Woldetsadik, Mazin Magzoub, Ramesh Jagannathan

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It is well known that bioactive ceramics exhibit specific biological affinities, especially in the area of tissue re-generation. In this context, we report the development of an eminently scalable, novel, supercritical CO₂ based process for the fabrication of hierarchically porous 'soft' CaCO₃ scaffolds. Porosity at the macro, micro, and nanoscales was obtained through process optimization of the so-called 'coffee-ring effect'. Exposure of these CaCO₃ scaffolds to monocytic THP-1 cells yielded negligible levels of tumor necrosis factor-alpha (TNF-α) thereby confirming the lack of immunogenicity of the scaffolds. ECM protein treatment of the scaffolds showed enhanced adsorption comparable to standard control such as glass. In vitro studies using osteoblast precursor cell line, MC3T3, also demonstrated the cytocompatibility of hierarchical porous CaCO₃ scaffolds.

Keywords: supercritical CO2, CaCO3 scaffolds, coffee-ring effect, ECM proteins

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Authors: Barbara Janari

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In this paper it is argued that the effect of the disjunctive temporality in Summertime (the third of J.M. Coetzee’s fictionalised memoirs) is two-fold: firstly, it reflects the memoir’s ambivalent, contradictory representations of place in order to emphasize the fractured sense of self growing up in South Africa during apartheid entailed for Coetzee. Secondly, it reconceives the autobiographical discourse as one that foregrounds the inherent fictionality of all texts. The memoir’s narrative is filtered through intricate textual strategies that disrupt the chronological movement of the narrative, evoking the labyrinthine ways in which the past and present intersect and interpenetrate each other. It is framed by entries from Coetzee’s Notebooks: it opens with entries that cover the years 1972–1975, and ends with a number of undated fragments from his Notebooks. Most of the entries include a short ‘memo’ at the end, added between 1999 and 2000. While the memos follow the Notebook entries in the text, they are separated by decades. Between the Notebook entries is a series of interviews conducted by Vincent, the text’s putative biographer, between 2007 and 2008, based on recollections from five people who had known Coetzee in the 1970s – a key period in John’s life as it marks both his return to South Africa after a failed emigration attempt to America, and the beginning of his writing career, with the publication of Dusklands in 1974. The relationship between the memoir’s various parts is a key feature of Coetzee’s representation of place in Summertime, which is constructed as a composite one in which the principle of reflexive referencing has to be adopted. In other words, readers have to suspend individual references temporarily until the relationships between the parts have been connected to each other. In order to apprehend meaning in the text, the disparate narrative elements have to first be tied together. In this text, then, the experience of time as ordered and chronological is ruptured. Instead, the memoir’s themes and patterns become apparent most clearly through reflexive referencing, by which relationships between disparate sections of the text are linked. The image of the fictional John that emerges from the text is a composite of this John and the author, J.M. Coetzee, and is one which embodies Coetzee’s often fraught relationship with his home country, South Africa.

Keywords: autobiography, place, reflexive referencing, temporality

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Authors: Evangelia Tsampali, Evangelos Yfantidis, Andreas Ioakim, Maria Stefanidou

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The purpose of this paper is the characterization of the effects of crystalline admixtures on concrete. Crystallites, aided by the presence of humidity, form idiomorphic crystals that block cracks and pores resulting in reduced porosity. In this project, two types of crystallines have been employed. The hydrophilic nature of crystalline admixtures helps the components to react with water and cement particles in the concrete to form calcium silicate hydrates and pore-blocking precipitates in the existing micro-cracks and capillaries. The underlying mechanism relies on the formation of calcium silicate hydrates and the resulting deposits of these crystals become integrally bound with the hydrated cement paste. The crystalline admixtures continue to activate throughout the life of the composite material when in the presence of moisture entering the concrete through hairline cracks, sealing additional gaps. The resulting concrete exhibits significantly increased resistance to water penetration under stress. Admixtures of calcium aluminates can also contribute to this healing mechanism in the same manner. However, this contribution is negligible compared to the calcium silicate hydrates due to the abundance of the latter. These crystalline deposits occur throughout the concrete volume and are a permanent part of the concrete mass. High-performance fibre reinforced cementitious composite (HPFRCC) were produced in the laboratory. The specimens were exposed in three healing conditions: water immersion until testing at 15 °C, sea water immersion until testing at 15 °C, and wet/dry cycles (immersion in tap water for 3 days and drying for 4 days). Specimens were pre-cracked at 28 days, and the achieved cracks width were in the range of 0.10–0.50 mm. Furthermore, microstructure observations and Ultrasonic Pulse Velocity tests have been conducted. Based on the outcomes, self-healing related indicators have also been defined. The results show almost perfect healing capability for specimens healed under seawater, better than for specimens healed in water while inadequate for the wet/dry exposure in both of the crystalline types.

Keywords: autogenous self-healing, concrete, crystalline admixtures, ultrasonic pulse velocity test

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Authors: Adebola Ajayi

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Ocimum gratissimum belongs to the Lamiaceae family and is know generally as African Basil. Ocimum gratissimum leaves are widely used as local condiments in diets. The leaves were destalked sorted, washed with potable water to remove dirts, air dried for 14 days under ambient temperature and milled into powder. The proximate composition and mineral contents of Ocimum gratissimum leaves were investigated. The proximate analysis showed the moisture, crude, protein, total ash, crude fiber, crude lipid and total carbohydrate contents were 10.72±0.01%, 12.98±0.10%, 10.95±0.42, 10.21±0.04%, 4.81±0.04% and 49.01±0.25% respectively. The results of the analysis showed that Ocimum gratissimum could be a good source of important food nutrients.

Keywords: African Basil, drying, Ocimum gratissimum, proximate

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Authors: Fatma Khaled, Khaoula Hidouri, Bechir Chaouachi

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Desalination using solar energy coupled with membrane techniques such as vacuum membrane distillation (VMD) is considered as an interesting alternative for the production of pure water. During this work, a developed model of a polytetrafluoroethylene (PTFE) hollow fiber membrane module of a VMD unit of seawater was carried out. This simulation leads to establishing a comparison between the effects of two different equations of the vaporization latent heat on the membrane surface temperature and on the unit productivity. Besides, in order to study the effect of putting membrane modules in series on the outlet fluid temperature and on the productivity of the process, a simulation was executed.

Keywords: vacuum membrane distillation, membrane module, membrane temperature, productivity

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Authors: Ji Hoi Heo, Jun Seong Park, Hyo Kim

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Geopolymer is an inorganic material synthesized by alkali activation of source materials rich in soluble SiO₂ and Al₂O₃. Many researches have studied the effect of aluminum species on the synthesis of geopolymer. However, it is still unclear about the influence of Al additives on the properties of geopolymer. The current study identified the role of the Al additive on the thermal performance of fly ash based geopolymer and observing the microstructure development of the composite. NaOH pellets were dissolved in water for 14 M (14 moles/L) sodium hydroxide solution which was used as an alkali activator. The weight ratio of alkali activator to fly ash was 0.40. Sodium aluminate powder was employed as an Al additive and added in amounts of 0.5 wt.% to 2 wt.% by the weight of fly ash. The mixture of alkali activator and fly ash was cured in a 75°C dry oven for 24 hours. Then, the hardened geopolymer samples were exposed to 300°C, 600°C and 900°C for 2 hours, respectively. The initial compressive strength after oven curing increased with increasing sodium aluminate content. It was also observed in SEM results that more amounts of geopolymer composite were synthesized as sodium aluminate was added. The compressive strength increased with increasing heating temperature from 300°C to 600°C regardless of sodium aluminate addition. It was consistent with the ATR-FTIR results that the peak position related to asymmetric stretching vibrations of Si-O-T (T: Si or Al) shifted to higher wavenumber as the heating temperature increased, indicating the further geopolymer reaction. In addition, geopolymer sample with higher content of sodium aluminate showed better compressive strength. It was also reflected on the IR results by more shift of the peak position assigned to Si-O-T toward the higher wavenumber. However, the compressive strength decreased after being exposed to 900°C in all samples. The degree of reduction in compressive strength was decreased with increasing sodium aluminate content. The deterioration in compressive strength was most severe in the geopolymer sample without sodium aluminate additive, while the samples with sodium aluminate addition showed better thermal durability at 900°C. This is related to the phase transformation with the occurrence of nepheline phase at 900°C, which was most predominant in the sample without sodium aluminate. In this work, it was concluded that sodium aluminate could be a good additive in the geopolymer synthesis by showing the improved compressive strength at elevated temperatures.

Keywords: compressive strength, fly ash based geopolymer, microstructure development, Na-aluminate

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Authors: Carlos E. Rodríguez-Rodríguez, Karla Ruiz-Hidalgo, Kattia Madrigal-Zúñiga, Juan Salvador Chin-Pampillo, Mario Masís-Mora, Elizabeth Carazo-Rojas

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One of the main causes of contamination linked to agricultural activities is the spillage and disposal of pesticides, especially during the loading, mixing or cleaning of agricultural spraying equipment. One improvement in the handling of pesticides is the use of biopurification systems (BPS), simple and cheap degradation devices where the pesticides are biologically degraded at accelerated rates. The biologically active core of BPS is the biomixture, which is constituted by soil pre-exposed to the target pesticide, a lignocellulosic substrate to promote the activity of ligninolitic fungi and a humic component (peat or compost), mixed at a volumetric proportion of 50:25:25. Considering the known ability of lignocellulosic fungi to degrade a wide range of organic pollutants, and the high amount of lignocellulosic waste used in biomixture preparation, the bioaugmentation of biomixtures with these fungi represents an interesting approach for improving biomixtures. The present work aimed at evaluating the effect of the bioaugmentation of rice husk based biomixtures with the fungus Trametes versicolor in the removal of the insectice/nematicide carbofuran (CFN) and to optimize the composition of the biomixture to obtain the best performance in terms of CFN removal and mineralization, reduction in formation of transformation products and decrease in residual toxicity of the matrix. The evaluation of several lignocellulosic residues (rice husk, wood chips, coconut fiber, sugarcane bagasse or newspaper print) revealed the best colonization by T. versicolor in rice husk. Pre-colonized rice husk was then used in the bioaugmentation of biomixtures also containing soil pre-exposed to CFN and either peat (GTS biomixture) or compost (GCS biomixture). After spiking with 10 mg/kg CBF, the efficiency of the biomixture was evaluated through a multi-component approach that included: monitoring of CBF removal and production of CBF transformation products, mineralization of radioisotopically labeled carbofuran (14C-CBF) and changes in the toxicity of the matrix after the treatment (Daphnia magna acute immobilization test). Estimated half-lives of CBF in the biomixtures were 3.4 d and 8.1 d in GTS and GCS, respectively. The transformation products 3-hydroxycarbofuran and 3-ketocarbofuran were detected at the moment of CFN application, however their concentration continuously disappeared. Mineralization of 14C-CFN was also faster in GTS than GCS. The toxicological evaluation showed a complete toxicity removal in the biomixtures after 48 d of treatment. The composition of the GCS biomixture was optimized using a central composite design and response surface methodology. The design variables were the volumetric content of fungally pre-colonized rice husk and the volumetric ratio compost/soil. According to the response models, maximization of CFN removal and mineralization rate, and minimization in the accumulation of transformation products were obtained with an optimized biomixture of composition 30:43:27 (pre-colonized rice husk:compost:soil), which differs from the 50:25:25 composition commonly employed in BPS. Results suggest that fungal bioaugmentation may enhance the performance of biomixtures in CFN removal. Optimization reveals the importance of assessing new biomixture formulations in order to maximize their performance.

Keywords: bioaugmentation, biopurification systems, degradation, fungi, pesticides, toxicity

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Authors: Nazia Tarannum, M. Ayaz Ahmad

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The main goal of this article is to report some interesting features for the fabrication/design of PEDOT:PSS based humidity sensor. Here first we fabricated humidity sensor and then studied its electro-mechanical characteristics. In general the humidity plays an important role in various private and government sectors all over the world. Monitoring and controlling the humidity is a great task for the reliable operation of various systems. The PEDOT:PSS is very much promising humidity sensor and also is fabricated by performing various analyses. The interdigited electrode (IDE) has channel length 200 microns prepared by lithography. Lithography of IDE was done on PPR coated glass substrate using negative mask and exposing it with UV light for 10 secs via DSA. During the above said fabrication, we have taken account for the following steps: •Plasma ashing of IDE •Spincoating of PEDOT:PSS was done @3000 rpm on IDE substrace •Baked the substrace at 130 °C up to time limit 15 mins. •Resistance measurement using Labtracer 2.9 software via Keithley 2400source meter.

Keywords: fabrication method, PEDOT:PSS material, humidity sensor, electro-mechanical

Procedia PDF Downloads 350

Authors: Oscar F. Toro, Alexia Pardo Figueroa, Brigitte M. Larico

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The development of new processes in the textile industry entails designing methodologies to select adequate supplies that fit these new processes requirements. This paper presents a methodology to select chemicals that fulfill a new process technical specifications. The proposed methodology involves three major phases: (1) Data collection of chemical products, (2) Qualitative pre-selection and (3) Laboratory tests. We have applied this methodology to the selection of a binder which will form a protective film above the textile fibers and bond them. Our findings were that, there exist five possible products that can be used in our new process: Arkofil, Elvanol, Size plus A, Size plus AC and Starch. This new methodology has both qualitative and experimental variables, and can be used to select supplies for new textile processes.

Keywords: binder, chemical products, selection methodology, textile supplies, textile fiber

Procedia PDF Downloads 296

Authors: D. Lopes, I. I. R. Baptista, R. F. Vieira, J. Vaz, H. Varela, O. M. Freitas, V. F. Domingues, R. Jorge, C. Delerue-Matos, S. A. Figueiredo

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Deodorization is nowadays a need in wastewater treatment plants. Nitrogen and sulphur compounds, volatile fatty acids, aldehydes and ketones are responsible for the unpleasant odours, being ammonia, hydrogen sulphide and mercaptans the most common pollutants. Although chemical treatments of the air extracted are efficient, these are more expensive than biological treatments, namely due the use of chemical reagents (commonly sulphuric acid, sodium hypochlorite and sodium hydroxide). Biofiltration offers the advantage of avoiding the use of reagents (only in some cases, nutrients are added in order to increase the treatment efficiency) and can be considered a sustainable process when the packing medium used is of natural origin. In this work the application of some natural materials locally available was studied both at laboratory and pilot scale, in a real wastewater treatment plant. The materials selected for this study were indigenous Portuguese forest materials derived from eucalyptus and pinewood, such as woodchips and bark, and coconut fiber was also used for comparison purposes. Their physico-chemical characterization was performed: density, moisture, pH, buffer and water retention capacity. Laboratory studies involved batch adsorption studies for ammonia and hydrogen sulphide removal and evaluation of microbiological activity. Four pilot-scale biofilters (1 cubic meter volume) were installed at a local wastewater treatment plant treating odours from the effluent receiving chamber. Each biofilter contained a different packing material consisting of mixtures of eucalyptus bark, pine woodchips and coconut fiber, with added buffering agents and nutrients. The odour treatment efficiency was monitored over time, as well as other operating parameters. The operation at pilot scale suggested that between the processes involved in biofiltration - adsorption, absorption and biodegradation - the first dominates at the beginning, while the biofilm is developing. When the biofilm is completely established, and the adsorption capacity of the material is reached, biodegradation becomes the most relevant odour removal mechanism. High odour and hydrogen sulphide removal efficiencies were achieved throughout the testing period (over 6 months), confirming the suitability of the materials selected, and mixtures thereof prepared, for biofiltration applications.

Keywords: ammonia hydrogen sulphide and removal, biofiltration, natural materials, odour control in wastewater treatment plants

Procedia PDF Downloads 302

Authors: Benchalak Muangmeesri

Abstract:

This research is experiment glaze from use cullet that is broken decayed from the used such as, glass bottle, windshield , etc. For seek raw material compensation that is raw material of the glaze in ceramic. The objective of the research for study the ratio of the glaze that is appropriate for glaze ceramic products and evaluate the experiment glaze on the vitreous china. The experiment has limits in using ceramic process such as, using calculation formula with triaxial, the empirical formula’s of Seger, and formula calculation is the percentage of the compound. for choose formula has will the possibility for glaze on vitreous china. The experiments in 108 triaxial can choose best formula and calculate is be left just 6 a formula for the calculation. The calculation is the percentage of the raw materials. Find that, three formulas in six formula there is percentage amount of the raw material that is cullet has the amount the little more 10 percentages then repeated experiment just three formulas. Overall, this research have three formulas for used its and we get all processes achieved and well done.

Keywords: cullet, glaze, pottery, ceramic

Procedia PDF Downloads 271

Authors: Guido Trautmann-Sáez, Mario Pérez-Won, Vilbett Briones, María José Bugueño, Gipsy Tabilo-Munizaga, Luis Gonzáles-Cavieres

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Shrimp by-products are a valuable source of protein. However, traditional protein extraction methods have limitations in terms of their efficiency. Protein extraction from shrimp (Pleuroncodes monodon) industrial by-products assisted with ohmic heating (OH), microwave (MW) and pulsed electric field (PEF). It was performed by chemical method (using NaOH and HCl 2M) assisted with OH, MW and PEF in a continuous flow system (5 ml/s). Protein determination, differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR). Results indicate a 19.25% (PEF) 3.65% (OH) and 28.19% (MW) improvement in protein extraction efficiency. The most efficient method was selected for the electrospinning process and obtaining fiber.

Keywords: electrospinning process, emerging technology, protein extraction, shrimp by-products

Procedia PDF Downloads 90

Authors: Tamrat Tesfaye, Bruce Sithole, K. Shabaridharan

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The use of natural dyes to replace synthetic dyes has been advocated for to circumvent the environmental problems associated with synthetic dyes. This paper is a preliminary study on the use of natural dyes extracted from eucalyptus and mango trees. Dyes extracted from eucalyptus bark gave more colourized material than the dyes extracted from eucalyptus leaves and mango pills and leaves. Additionally, the extracts exhibited a deeper colour shade. Cotton fiber dyed using the same dye but with different mordants resulted in fabric that exhibited different colours. It appears that natural dyes from these plants could be effective dyes for use on cotton fabrics especially considering that the dyes exhibited excellent colour fastness.

Keywords: natural dyes, mango, eucalyptus, cotton, mordants, colour fastness

Procedia PDF Downloads 357