Search results for: solvent evaporation

Authors: Kyung-Soon Choi, Ji-Young Hwang, Young-Hee Pyo

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Vinegars have been used as an alternative remedy for treating gout, but the scientific basis remains to be elucidated. In this study, acetic acid fermentation was applied for the first time to Monascus-fermented soybeans to examine its effect on the bioactive components together with the xanthine oxidase inhibitory (XOI) activity of the soy vinegar. The content of total phenols (0.47~0.97 mg gallic acid equivalents/mL) and flavonoids (0.18~0.39 mg quercetin equivallents/mL) were spectrophotometrically determined, and the content of organic acid (10.22~59.76 mg/mL) and isoflavones (6.79~7.46 mg/mL) were determined using HPLC-UV. The analytical method for ubiquinones (0.079~0.276 μg/mL) employed saponification before solvent extraction and quantification using LC-MS. Soy vinegar also showed significant XOI (95.3%) after 20 days of acetic acid fermentation at 30 °C. The results suggest that soy vinegar has potential as a novel medicinal food.

Keywords: acetic acid fermentation, bioactive component, soy vinegar, xanthine oxidase inhibitory activity

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Authors: Bokolombe Pitchou Ngoy, John Mack, Tebello Nyokong

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Synthesis and photochemical studies of BODIPY dyes have been investigated in this work in order to have a broad benchmark of this functionalized photosensitizer for biological applications such as photodynamic therapy or antimicrobial activity. The common acid catalyzed synthetic method was used, and BODIPY dyes were obtained in quite a good yield (25 %) followed by bromination and Knoevenagel condensation to afford the BODIPY dyes conjugated with maximum absorbance in the near-infrared region of the electromagnetic spectrum. The fluorescence lifetimes, fluorescence quantum yield, and Singlet oxygen quantum yield of the conjugated BODIPY dyes were determined in different solvents by using Time Correlation Single Photon Counting (TCSPC), fluorimeter, and Laser Flash Photolysis respectively. It was clearly shown that the singlet oxygen quantum yield was higher in THF followed by DMSO compared to another solvent. The same trend was observed for the fluorescence lifetimes.

Keywords: BODIPY, photodynamic therapy, photosensitizer, singlet oxygen

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Authors: M. Kheirandish, S. Borhani

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In this experiment Polystyrene/Zinc-oxide (PS/ZnO) nanocomposite fibers were produced by electrospinning technique using limonene as a green solvent. First, the morphology of electrospun pure polystyrene (PS) and PS/ZnO nanocomposite fibers investigated by SEM. Results showed the PS fiber diameter decreased by increasing concentration of Zinc Oxide nanoparticles (ZnO NPs). Thermo Gravimetric Analysis (TGA) results showed thermal stability of nanocomposites increased by increasing ZnO NPs in PS electrospun fibers. Considering Differential Scanning Calorimeter (DSC) thermograms for electrospun PS fibers indicated that introduction of ZnO NPs into fibers affects the glass transition temperature (Tg) by reducing it. Also, UV protection properties of nanocomposite fibers were increased by increasing ZnO concentration. Evaluating the effect of metal oxide NPs amount on mechanical properties of electrospun layer showed that tensile strength and elasticity modulus of the electrospun layer of PS increased by addition of ZnO NPs. X-ray diffraction (XRD) pattern of nanopcomposite fibers confirmed the presence of NPs in the samples.

Keywords: electrospininng, nanoparticle, polystyrene, ZnO

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Authors: H. Troudi, M. Ghiss, Z. Tourki, M. Ellejmi

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Packed columns of liquefied petroleum gas (LPG) consists of separating the liquid mixture of propane and butane to pure gas components by the distillation phenomenon. The flow of the gas and liquid inside the columns is operated by two ways: The co-current and the counter current operation. Heat, mass and species transfer between phases represent the most important factors that influence the choice between those two operations. In this paper, both processes are discussed using computational CFD simulation through ANSYS-Fluent software. Only 3D half section of the packed column was considered with one packed bed. The packed bed was characterized in our case as a porous media. The simulations were carried out at transient state conditions. A multi-component gas and liquid mixture were used out in the two processes. We utilized the Euler-Lagrange approach in which the gas was treated as a continuum phase and the liquid as a group of dispersed particles. The heat and the mass transfer process was modeled using multi-component droplet evaporation approach. The results show that the counter-current process performs better than the co-current, although such limitations of our approach are noted. This comparison gives accurate results for computations times higher than 2 s, at different gas velocity and at packed bed porosity of 0.9.

Keywords: co-current, counter-current, Euler-Lagrange model, heat transfer, mass transfer

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Authors: Randa Slatnia

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In this study, the nanostructured stable phase identification elaborated by nickel nitrate hyxahydrate and thiourea compounds. After the preparation of the solution (Stirred mixture with methanol as solvent), a deposition of eight layers of this solution on a glass substrate and annealed at 300 °C for energy applications. The annealed sample was analyzed by X-ray Grazing incidence diffraction (GID) with a Bruker D8 Advance diffractometer using Cu Kα1 radiation at 40 kV and 40 mA (1600 W) and Scanning electron microscopy (Thermo Fisher environmental SEM). The results of XRD-GID analysis for the prepared sample showed the formation of an identified stable phase NiS2 and the XRD-GID pattern of the elaborated sample with eight layers prepared solution and annealed show wide and characteristic peaks of the NiS2 with cubic structure (ICDD card no. PDF 01-078-4702). The morphology of the NiS2 thin films confirmed by XRD-GID analysis was investigated by ESEM showed a surface with a uniform and homogeneous distribution nanostructure.

Keywords: nickel sulfide, thin films, XRD, ESEM

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Authors: Kumalo F. I., Malimabe M. A., Gumede T. P., Mosoabisane M. F. T.

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This study investigates the fabrication and characterization of bio-nanocomposites consisting of poly (butylene succinate) (PBS) and poly (ԑ-caprolactone) (PCL), reinforced with cellulose extracted from Eucomis autumnalis, a medicinal plant. Bio-nanocomposite films were prepared using the solvent casting method, with cellulose content ranging from 1 to 3 wt%. Comprehensive analysis was conducted using FTIR, SEM, TEM, DSC, TGA, and XRD, to assess morphological, thermal, and structural properties. The results indicated significant improvements in the thermal stability and morphological properties with increasing cellulose content, showcasing the potential of these materials for tissue engineering applications. The use of cellulose extracted from a medicinal plant highlight the potential for sustainable and biocompatible materials in biomedical applications.

Keywords: Bionanocomposites, poly(butylene succinate), poly(caprolactone), eucomis autumnalis, medicinal plant

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Authors: Allouache Nadia

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Solid adsorption cooling machines have been extensively studied recently. They constitute very attractive solutions recover important amount of industrial waste heat medium temperature and to use renewable energy sources such as solar energy. The development of the technology of these machines can be carried out by experimental studies and by mathematical modelisation. This last method allows saving time and money because it is suppler to use to simulate the variation of different parameters. The adsorption cooling machines consist essentially of an evaporator, a condenser and a reactor (object of this work) containing a porous medium, which is in our case the activated carbon reacting by adsorption with ammoniac. The principle can be described as follows: When the adsorbent (at temperature T) is in exclusive contact with vapour of adsorbate (at pressure P), an amount of adsorbate is trapped inside the micro-pores in an almost liquid state. This adsorbed mass m, is a function of T and P according to a divariant equilibrium m=f (T,P). Moreover, at constant pressure, m decreases as T increases, and at constant adsorbed mass P increases with T. This makes it possible to imagine an ideal refrigerating cycle consisting of a period of heating/desorption/condensation followed by a period of cooling/adsorption/evaporation. Effect of key parameters on the machine performances are analysed and discussed.

Keywords: activated carbon-ammoniac pair, effect of key parameters, numerical modeling, solar cooling machine

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Authors: Tolga Aydin, M. Fatih Alaeddinoğlu

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People, throughout the history, have made estimates and inferences about the future by using their past experiences. Developing information technologies and the improvements in the database management systems make it possible to extract useful information from knowledge in hand for the strategic decisions. Therefore, different methods have been developed. Data mining by association rules learning is one of such methods. Apriori algorithm, one of the well-known association rules learning algorithms, is not commonly used in spatio-temporal data sets. However, it is possible to embed time and space features into the data sets and make Apriori algorithm a suitable data mining technique for learning spatio-temporal association rules. Lake Van, the largest lake of Turkey, is a closed basin. This feature causes the volume of the lake to increase or decrease as a result of change in water amount it holds. In this study, evaporation, humidity, lake altitude, amount of rainfall and temperature parameters recorded in Lake Van region throughout the years are used by the Apriori algorithm and a spatio-temporal data mining application is developed to identify overflows and newly-formed soil regions (underflows) occurring in the coastal parts of Lake Van. Identifying possible reasons of overflows and underflows may be used to alert the experts to take precautions and make the necessary investments.

Keywords: apriori algorithm, association rules, data mining, spatio-temporal data

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Authors: Andrés Quiroz, Emilio Hormazábal, Ana Mutis, Fernando Ortega, Loreto Méndez, Leonardo Parra

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Red clover root borer, Hylastinus obscurus Marsham (Coleoptera: Curculionidae), is the main insect pest associated to red clover, Trifolium pratense L. An average of 1.5 H. obscurus per plant can cause 5.5% reduction in forage yield in pastures of two to three years old. Moreover, insect attack can reach 70% to 100% of the plants. To our knowledge, there is no a chemical strategy for controlling this pest. Therefore alternative strategies for controlling H. obscurus are a high priority for red clover producers. One of this alternative is related to the study of secondary metabolites involved in intrinsic chemical defenses developed by plants, such as isoflavonoids. The isoflavonoids formononetin and daidzein have elicited an antifeedant and phagostimult effect on H. obscurus respectively. However, we do not know how is the dynamic variation of these isoflavonoids under field conditions. The main objective of this work was to evaluate the variation of the antifeedant isoflavonoids formononetin, the phagostimulant isoflavonoids daidzein, and their respective glycosides over time in different ecotypes of red clover. Fourteen red clover ecotypes (8 cultivars and 6 experimental lines), were collected at INIA-Carillanca (La Araucanía, Chile). These plants were established in October 2015 under irrigated conditions. The cultivars were distributed in a randomized complete block with three replicates. The whole plants were sampled in four times: 15th October 2016, 12th December 2016, 27th January 2017 and 16th March 2017 with sufficient amount of soil to avoid root damage. A polar fraction of isoflavonoid was obtained from 20 mg of lyophilized root tissue extracted with 2 mL of 80% MeOH for 16 h using an orbital shaker in the dark at room temperature. After, an aliquot of 1.4 mL of the supernatant was evaporated, and the residue was resuspended in 300 µL of 45% MeOH. The identification and quantification of isoflavonoid root extracts were performed by the injection of 20 µL into a Shimadzu HPLC equipped with a C-18 column. The sample was eluted with a mobile phase composed of AcOH: H₂O (1:9 v/v) as solvent A and CH₃CN as solvent B. The detection was performed at 260 nm. The results showed that the amount of aglycones was higher than the respective glycosides. This result is according to the biosynthetic pathway of flavonoids, where the formation of glycoside is further to the glycosides biosynthesis. The amount of formononetin was higher than daidzein. In roots, where H. obscurus spent the most part of its live cycle, the highest content of formononetin was found in G 27, Pawera, Sabtoron High, Redqueli-INIA and Superqueli-INIA cvs. (2.1, 1.8, 1.8, 1.6 and 1.0 mg g⁻¹ respectively); and the lowest amount of daidzein were found Superqueli-INIA (0.32 mg g⁻¹) and in the experimental line Sel Syn Int4 (0.24 mg g⁻¹). This ecotype showed a high content of formononetin (0.9 mg g⁻¹). This information, associated with cultural practices, could help farmers and breeders to reduce H. obscurus in grassland, selecting ecotypes with high content of formononetin and low amount of daidzein in the roots of red clover plants. Acknowledgements: FONDECYT 1141245 and 11130715.

Keywords: daidzein, formononetin, isoflavonoid glycosides, trifolium pratense

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Authors: Apu Kumar Saha, Mrinmoy Majumder

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The increase in the concentration of Green House gases all over the World has induced global warming phenomena whereby the average temperature of the world has aggravated to impact the pattern of climate in different regions. The frequency of extreme event has increased, early onset of season and change in an average amount of rainfall all are engrossing the conclusion that normal pattern of climate is changing. Sophisticated and complex models are prepared to estimate the future situation of the climate in different zones of the Earth. As hydro-energy is directly related to climatic parameters like rainfall and evaporation such energy resources will have to sustain the onset of the climatic abnormalities. The present investigation has tried to assess the impact of climatic abnormalities upon hydropower potential of different regions of the World. In this regard multi-criteria, decision making, and the neural network is used to predict the impact of the change cognitively by an index. The results from the study show that hydro-energy potential of Asian region is mostly vulnerable with respect to other regions of the world. The model results also encourage further application of the index to analyze the impact of climate change on the potential of hydro-energy.

Keywords: hydro-energy potential, neural networks, multi criteria decision analysis, environmental and ecological engineering

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Authors: Ugbor Raphael Oluchukwu

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Focusing on liquidity comes more naturally to a Chief Executive Officer than an Accountant who is trained to practice accrual accounting. When business is just commencing, it is essentially run on a cheque book (cash accounting) and for as long as there is cash in the accounts, the business is solvent. When complexity sets in and the business adopts financial accounting, the effect of liquidity and cash management becomes more pronounced. The management of cash no doubts impacts positively on the survival and growth of firms. What is in doubt is the amount of cash to be held by a firm as enough cash to enable the firm stay “afloat”. The focus of this paper is to determine liquidity and cash management in business, the Nigerian case. The specific objectives of the study are to do a theoretical review of the amount of cash to be held by a firm as enough cash to enable it stay afloat and to do a theoretical analysis to show the effect of cash flow on the survival and growth of firms in Nigeria.

Keywords: cash, firm survival, growth, liquidity management

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Authors: Amthal Al-Gailani, Olujide Sanni, Thibaut Charpentier, Anne Neville

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Formation of inorganic scale on heat transfer surfaces is a serious problem encountered in industrial, commercial, and domestic heat exchangers and systems. Several industries use potable/groundwater sources such as rivers, lakes, and oceans to use water as a working fluid in heat exchangers and steamers. As potable/surface water contains diverse salt ionic species, the scaling kinetics and deposit morphology are expected to be different from those found in artificially hardened solutions. In this work, scale formation on the heat transfer surfaces from potable water has been studied using a once-through open flow cell under atmospheric pressure. The surface scaling mechanism and deposit morphology are investigated at high surface temperature. Thus the water evaporation process has to be considered. The effect of surface temperature, flow rate, and inhibitor deployment on the thermal resistance and morphology of the scale have been investigated. The study findings show how an increase in surface temperature enhances the crystallization reaction kinetics on the surface. There is an increase in the amount of scale and the resistance to heat transfer. The fluid flow rate also increases the fouling resistance and the thickness of the scale layer.

Keywords: fouling, heat exchanger, thermal resistance, crystallization, potable water

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Authors: Y. H. Hwang, J. Won, Y. S. Kang

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Supported ionic liquid membranes (SILMs) have attracted due to the negligible vapor pressure of ionic liquids (ILs) as well as the high gas selectivity for specific gases such as CO2 or olefin. 1-ethyl-3-methylimidazolium tricyanomethanide ([EMIM][TCM]), 1-butyl-3-methylimidazolium tricyanomethanide ([BMIM][TCM]), show high CO2 solubility, CO2 absorption, rapid CO2 absorption rate and negligible vapor pressure, SILMs using these ILs have been good candidates as CO2 separation membranes. However, SILM has to be operated at a low differential pressure to prevent the solvent from being expelled from the pores of supported membranes. In this paper, we improve the mechanical strength by forming ion gels which provide the stability while it retains the diffusion properties of the liquid stage which affects the gas separation properties. The ion gel was created by the addition of tri-block copolymer, poly(styrene-ethylene oxide-b-styrene) in RTIL. SILM using five different RTILs, are investigated with and without ion gels. The gas permeance were measured and the gas performance with and without the SEOS were investigated.

Keywords: ion gel, ionic liquid, membrane, nanostructure

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Authors: Italo Luigi de Paoli

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The use of synthetic soil for the vegetables cultivation in conditions of limited water consumption The separate collection of urban organic waste and green waste for the countries of the European Union averages 100 kg / inhabitant x year with an annual growth of about 10%. The production of quality compost averages 38% - 40% of the production of organic waste material. Most of the compost produced is used as an organic soil improver in those nutrient-poor soils in order to improve its quality. This study seeks to enhance the production of quality compost by creating a synthetic soil, where the percentages of compost on average oscillate between 50% and 60% in which, with appropriate precautions, different species of horticultural can be grown in conditions of high environmental safety without the use of pesticides and with a consumption of water used for irrigation limited to the actual evaporation of the plants. The project started in 2018 and is still ongoing, confirms its validity through a series of different horticultural productions, especially if this technology is applied where the availability of land suitable for the cultivation of vegetables is limited and where the use of water for irrigation represents a cultural criticality. Furthermore, the creation of "open field" crops, together with their automation, represents a further possibility in the concrete development of such technologies, giving the final product organoleptic characteristics equal if not superior to what the market offers today for human nutrition.

Keywords: water scarcity, compost, vegetable foods, syntetic soil

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Authors: Mohammad Reza Farzami Pour

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Determination of genetic variation is useful for plant breeding and hence production of more efficient plant species under different conditions, like drought stress. In this study, a sample of 28 recombinant inbred lines (RILs) of wheat developed from the cross of Norstar and Zagross varieties, together with their parents, were evaluated for two years (2010-2012) under normal and water stress conditions using split plot design with three replications. Main plots included two irrigation treatments of 70 and 140 mm evaporation from Class A pan and sub-plots consisted of 30 genotypes. The effect of genotypes and interaction of genotypes with years and water regimes were significant for all characters. Significant genotypic effect implies the existence of genetic variation among the lines under study. Heritability estimates were high for 1000 grain weight (0.87). Biomass and grain yield showed the lowest heritability values (0.42 and 0.50, respectively). Highest genotypic and phenotypic coefficients of variation (GCV and PCV) belonged to harvest index. Moderate genetic advance for most of the traits suggested the feasibility of selection among the RILs under investigation. Some RILs were higher yielding than either parent at both environments.

Keywords: wheat, genetic gain, heritability, recombinant inbred lines

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Authors: Rahim Ada, Mustafa Harmankaya, Sadiye Ayse Celik

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The safflower seed contains about 25-40% solvent extract and 20-33% fiber. It is well known that dietary phospholipids lower serum cholesterol levels effectively. The nutrient composition of safflower seed changes depending on region, soil and genotypes. This research was made by using of six natural selected (A22, A29, A30, C12, E1, F4, G8, G12, J27) and three commercial (Remzibey, Dincer, Black Sun1) varieties of safflower genotypes. The research was conducted on field conditions for two years (2009 and 2010) in randomized complete block design with three replications in Konya-Turkey ecological conditions. Oil contents, mineral contents and their correlations were determined in the research. According to the results, oil content was ranged from 22.38% to 34.26%, while the minerals were in between the following values: 1469, 04-2068.07 mg kg^-1 for Ca, 7.24-11.71 mg kg^-1 for B, 13.29-17.41 mg kg^-1 for Cu, 51.00-79.35 mg kg^-1 for Fe, 3988-6638.34 mg kg^-1 for K, 1418.61-2306.06 mg kg^-1 for Mg, 11.37-17.76 mg kg^-1 for Mn, 4172.33-7059.58 mg kg^-1 for P and 32.60-59.00 mg kg^-1 for Zn. Correlation analysis that was made separately for the commercial varieties and wild lines showed that high level of oil content was negatively affected by all the investigated minerals except for K and Zn in the commercial varieties.

Keywords: safflower, oil, quality, mineral content

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Authors: Haibo Sheng, Yuan Hu

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Spinel structure Zinc stannate (Zn2SnO4, ZS)/Graphene was successfully synthesized by a simple in situ hydrothermal route. Morphological study and structure analysis confirmed the homogenously loading of ZS on the graphene sheets. Then, the resulted ZS/graphene hybrids were incorporated into epoxy resin to form EP/ZS/graphene composites by a solvent dispersion method. Improved thermal stability was investigated by Thermogravimetric Analysis (TGA). Cone calorimeter result showed low peak heat release rate (PHRR). Toxical gases release during combustion was evaluated by a facile device organized in our lab. The results showed that the release of NOx, HCN decrease of about 55%. Also, TG-IR technology was used to investigate the gas release during the EP decomposition process. The CO release had decreased about 80%.The EP/G/ZS showed lowest hazards during combustion (including flame retardancy, thermal stability, lower toxical gases release and so on) than pure EP.

Keywords: fire hazards, zinc stannate, epoxy resin, toxical gas hazards

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Authors: Eloise C. Tredenick, Troy W. Farrell, W. Alison Forster, Steven T. P. Psaltis

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The agriculture industry requires improved efficacy of sprays being applied to crops. More efficacious sprays provide many environmental and financial benefits. The plant leaf cuticle is known to be the main barrier to diffusion of agrochemicals within the leaf. The importance of a mathematical model to simulate uptake of agrochemicals in plant cuticles has been noted, as the results of each uptake experiments are specific to each formulation of active ingredient and plant species. In this work we develop a mathematical model and numerical simulation for the uptake of ionic agrochemicals through aqueous pores in plant cuticles. We propose a nonlinear porous diffusion model of ionic agrochemicals in isolated cuticles, which provides additions to a simple diffusion model through the incorporation of parameters capable of simulating plant species' variations, evaporation of surface droplet solutions and swelling of the aqueous pores with water. The model could feasibly be adapted to other ionic active ingredients diffusing through other plant species' cuticles. We validate our theoretical results against appropriate experimental data, discuss the key sensitivities in the model and relate theoretical predictions to appropriate physical mechanisms.

Keywords: aqueous pores, ionic active ingredient, mathematical model, plant cuticle, porous diffusion

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Authors: Yong Ren, Yaping Zhang

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A numerical model has been developed to investigate the thermally triggered release kinetics for drug delivery using phase change material as shell of microcapsules. Biocompatible material n-Eicosane is used as demonstration. PCM shell of microcapsule will remain in solid form after the drug is taken, so the drug will be encapsulated by the shell, and will not be released until the target body part of lesion is exposed to external heat source, which will thermally trigger the release kinetics, leading to solid-to-liquid phase change. The findings can lead to better understanding on the key effects influencing the phase change process for drug delivery applications. The facile approach to release drug from core/shell structure of microcapsule can be well integrated with organic solvent free fabrication of microcapsules, using double emulsion as template in microfluidic aqueous two phase system.

Keywords: phase change material, drug release kinetics, double emulsion, microfluidics

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Authors: Maxim S. Botalov, Svetlana М. Titova, Denis V. Smyshlyaev, Grigory M. Bunkov, Evgeny V. Kirillov, Sergey V. Kirillov, Maxim A. Mashkovtsev, Vladimir N. Rychkov

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In uranium production, in-situ leaching (ISL) with its relatively low cost has become an important technology. As the orebody containing uranium most often contains a considerable value of other metals, particularly rare earth metals it has rendered feasible to recover the REM from the barren ISL solutions, from which the major uranium content has been removed. Ural Federal University (UrFU, Ekaterinburg, Russia) have performed joint research on the development of industrial technologies for the extraction of REM and Scandium compounds from Uranium ISL solutions. Leaching experiments at UrFU have been supported with multicomponent solution model. The experimental work combines solvent extraction with advanced ion exchange methodology in a pilot facility capable of treating 500 kg/hr of solids. The pilot allows for the recovery of a 99% concentrate of scandium oxide and collective concentrate with over 50 % REM content, with further recovery of heavy and light REM concentrates (99%).

Keywords: extraction, ion exchange, rare earth elements, scandium

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Authors: Kahina Bedda, Boudjema Hamada

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Environmental regulations have been introduced in many countries around the world to reduce the sulfur content of diesel fuel to ultra low levels with the intention of lowering diesel engine’s harmful exhaust emissions and improving air quality. Removal of sulfur containing compounds from diesel feedstocks to produce ultra low sulfur diesel fuel by extraction with selective solvents has received increasing attention in recent years. This is because the sulfur extraction technologies compared to the hydrotreating processes could reduce the cost of desulfurization substantially since they do not demand hydrogen, and are carried out at atmospheric pressure. In this work, the desulfurization of distillate gasoil by liquid-liquid extraction with N, N-dimethylformamide was investigated. This fraction was recovered from a mixture of Hassi Messaoud crude oils and Hassi R'Mel gas-condensate in Algiers refinery. The sulfur content of this cut is 281 ppm. Experiments were performed in six-stage with a ratio of solvent:feed equal to 3:1. The effect of the extraction temperature was investigated in the interval 30 ÷ 110°C. At 110°C the yield of refined gas oil was 82% and its sulfur content was 69 ppm.

Keywords: desulfurization, gasoil, N, N-dimethylformamide, sulfur content

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Authors: Amir Doustgani

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Melt electrospinning is a safe and simple technique for the production of micro and nanofibers which can be an alternative to conventional solvent electrospinning. The effects of various melt-electrospinning parameters, including molecular weight, electric field strength, flow rate and temperature on the morphology and fiber diameter of polylactic acid were studied. It was shown that molecular weight was the predominant factor in determining the obtainable fiber diameter of the collected fibers. An orthogonal design was used to examine process parameters. Results showed that molecular weight is the most effective parameter on the average fiber diameter of melt electrospun PLA nanofibers and the flow rate has the less important impact. Mean fiber diameter increased by increasing MW and flow rate, but decreased by increasing electric field strength and temperature. MFD of optimized fibers was below 100 nm and the result of software was in good agreement with the experimental condition.

Keywords: fiber formation, processing, spinning, melt blowing

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Authors: Yardfon Tanongkankit, Kanjana Narkprasom, Nukrob Narkprasom, Khwanruthai Saiupparat, Phatthareeya Siriwat

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Gac fruit (Momordica cochinchinensis (Lour.) Spreng) possesses high potential for health food as it contains high lycopene contents. The objective of this study was to optimize the extraction of lycopene from gac arils using the microwave extraction method. Response surface method was used to find the conditions that optimize the extraction of lycopene from gac arils. The parameters of extraction used in this study were extraction time (120-600 seconds), the solvent to sample ratio (10:1, 20:1, 30:1, 40:1 and 50:1 mL/g) and set microwave power (100-800 watts). The results showed that the microwave extraction condition at the extraction time of 360 seconds, the sample ratio of 30:1 mL/g and the microwave power of 450 watts were suggested since it exhibited the highest value of lycopene content of 9.86 mg/gDW. It was also observed that lycopene contents extracted from gac arils by microwave method were higher than that by the conventional method.

Keywords: conventional extraction, Gac arils, microwave-assisted extraction, Lycopene

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Authors: Christina Drosou, Konstantina E. Kyriakopoulou, Andreas Bimpilas, Dimitrios Tsimogiannis, Magdalini C. Krokida

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Rationale: Agiorgitiko is one of the most widely-grown and commercially well-established red wine varieties in Greece. Each year viticulture industry produces a large amount of waste consisting of grape skins and seeds (pomace) during a short period. Grapes contain polyphenolic compounds which are partially transferred to wine during winemaking. Therefore, winery wastes could be an alternative cheap source for obtaining such compounds with important antioxidant activity. Specifically, red grape waste contains anthocyanins and flavonols which are characterized by multiple biological activities, including cardioprotective, anti-inflammatory, anti-carcinogenic, antiviral and antibacterial properties attributed mainly to their antioxidant activity. Ultrasound assisted extraction (UAE) is considered an effective way to recover phenolic compounds, since it combines the advantage of mechanical effect with low temperature. Moreover, green solvents can be used in order to recover extracts intended for used in the food and nutraceutical industry. Apart from the extraction, pre-treatment process like drying can play an important role on the preservation of the grape pomace and the enhancement of its antioxidant capacity. Objective: The aim of this study is to recover natural extracts from winery waste with high antioxidant capacity using green solvents so they can be exploited and utilized as enhancers in food or nutraceuticals. Methods: Agiorgitiko grape pomace was dehydrated by air drying (AD) and accelerated solar drying (ASD) in order to explore the effect of the pre-treatment on the recovery of bioactive compounds. UAE was applied in untreated and dried samples using water and water: ethanol (1:1) as solvents. The total antioxidant potential and phenolic content of the extracts was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and Folin-Ciocalteu method, respectively. Finally, the profile of anthocyanins and flavonols was specified using HPLC-DAD analysis. The efficiency of processes was determined in terms of extraction yield, antioxidant activity, phenolic content and the anthocyanins and flavovols profile. Results & Discussion: The experiments indicated that the pre-treatment was essential for the recovery of highly nutritious compounds from the pomace as long as the extracts samples showed higher phenolic content and antioxidant capacity. Water: ethanol (1:1) was considered a more effective solvent on the recovery of phenolic compounds. Moreover, ASD grape pomace extracted with the solvent system exhibited the highest antioxidant activity (IC50=0.36±0.01mg/mL) and phenolic content (TPC=172.68±0.01mgGAE/g dry extract), followed by AD and untreated pomace. The major compounds recovered were malvidin3-O-glucoside and quercetin3-O-glucoside according to the HPLC analysis. Conclusions: Winery waste can be exploited for the recovery of nutritious compounds using green solvents such as water or ethanol. The pretreatment of the pomace can significantly affect the concentration of phenolic compounds, while UAE is considered a highly effective extraction process.

Keywords: agiorgitico grape pomace, antioxidants, phenolic compounds, ultrasound assisted extraction

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Authors: Apolinar Picado, Steve Alfaro, Rafael Gamero

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Energy and exergy analyses of thin-layer drying of pineapple slices (Ananas comosus L.) were conducted in a laboratory tunnel dryer. Drying experiments were carried out at three temperatures (100, 115 and 130 °C) and an air velocity of 1.45 m/s. The effects of drying variables on energy utilisation, energy utilisation ratio, exergy loss and exergy efficiency were studied. The enthalpy difference of the gas increased as the inlet gas temperature increase. It is observed that at the 75 minutes of the drying process the outlet gas enthalpy achieves a maximum value that is very close to the inlet value and remains constant until the end of the drying process. This behaviour is due to the reduction of the total enthalpy within the system, or in other words, the reduction of the effective heat transfer from the hot gas flow to the vegetable being dried. Further, the outlet entropy exhibits a significant increase that is not only due to the temperature variation, but also to the increase of water vapour phase contained in the hot gas flow. The maximum value of the exergy efficiency curve corresponds to the maximum value observed within the drying rate curves. This maximum value represents the stage when the available energy is efficiently used in the removal of the moisture within the solid. As the drying rate decreases, the available energy is started to be less employed. The exergetic efficiency was directly dependent on the evaporation flux and since the convective drying is less efficient that other types of dryer, it is likely that the exergetic efficiency has relatively low values.

Keywords: efficiency, energy, exergy, thin-layer drying

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Authors: Nora A. Hamad, Ayman M. Atta, Adel A. H. Abdel-Rahman

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Two malice anhydride esters were prepared using long chain aliphatic alcohols (C8H17OH and C12H25OH, 1:1 mole ratio). Three series of crosslinked homo and copolymers of maleate esters with octadecyl acrylate and acrylic acid were prepared respectively through suspension copolymerization. The monomers were mixed with 0.02 Wt% of BP initiator, PVA 1% (170 ml for each 100g of monomers) and different weight ratios of DVB crosslinked (1% and 4%) in cyclohexane. The prepared crosslinked homo and copolymers were characterized by SEM, TGA and FTIR spectroscopic analyses. The prepared polymers were coated onto poly (ethylene terephethalate) nonwoven fiber (NWPET). The effect of copolymerization feed composition, crosslinker wt% and reaction media or solvent on swelling properties of crosslinked polymers were studied through the oil absorption tests in toluene and 10% of diluted crude oil with toluene.

Keywords: acrylic acid, crosslinked copolymers, maleate ester, poly(ethylene terephethalate) nonwoven fiber (NWPET), oil absorbency, octadecyl acrylat

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Authors: Samira Melki, Moncef Gueddari

Abstract:

In Tunisia, solid wastes storage continue to be uncontrolled. It is eliminated by land raising without any protection measurement against water table and soil contamination. Several industries are located in Sfax area, especially those of the Tunisian Chemical Group (TCG) for the enrichment and transformation of phosphate. The activity of the TCG focuses primarily on the production of chemical fertilizers and phosphoric acid, by transforming natural phosphates. This production generates gaseous emissions, liquid discharges and huge amounts of phosphogypsum (PG) stored directly on the soil surface. Groundwater samples were collected from Tunisian Chemical Group (TCG) site, to assess the effects of phosphogypsum leatchate on groundwater quality. The measurements of various physicochemical parameters including heavy metals (Al, Fe, Zn and F) and stable isotopes of the water molecule (¹⁸O, ²H) were determined in groundwater samples and are reported. The moderately high concentrations of SO₄⁼, Ortho-P, NH₄⁺ Al and F⁻ in groundwater particularly near to the phosphogypsum storage site, likely indicate that groundwater quality is being significantly affected by leachate percolation. The effect of distance of the piezometers from the pollution source was also investigated. The isotopic data of water molecule, showed that the waters of the Sfax-Agreb aquifer amount to recent-evaporation induced rainfall.

Keywords: phosphogypsum leatchate, groundwater quality, pollution, stable isotopes, Sfax-Agareb, Tunisia

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Authors: B. Pavan Kumar Reddy, P. Michael Preetam Raj, Souri Banerjee, Souvik Kundu

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In this work, the fabrication and characterization of copper-doped zinc oxide (Cu:ZnO) based memristor devices with aluminum (Al) and indium tin oxide (ITO) metal electrodes are reported. The thin films of Cu:ZnO was synthesized using low-cost and low-temperature chemical process. The Cu:ZnO was then deposited onto ITO bottom electrodes using spin-coater technique, whereas the top electrode Al was deposited utilizing physical vapor evaporation technique. Ellipsometer was employed in order to measure the Cu:ZnO thickness and it was found to be 50 nm. Several surface and materials characterization techniques were used to study the thin-film properties of Cu:ZnO. To ascertain the efficacy of Cu:ZnO for memristor applications, electrical characterizations such as current-voltage (I-V), data retention and endurance were obtained, all being the critical parameters for next-generation memory. The I-V characteristic exhibits switching behavior with asymmetrical hysteresis loops. This work imputes the resistance switching to the positional drift of oxygen vacancies associated with respect to the Al/Cu:ZnO junction. Further, a non-linear curve fitting regression techniques were utilized to determine the equivalent circuit for the fabricated Cu:ZnO memristors. Efforts were also devoted in order to establish its potentiality for different electronic applications.

Keywords: copper doped, metal-oxides, oxygen vacancies, resistive switching

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Authors: Mohd. Akram, A. A. M. Saeed

Abstract:

Surfactants are widely used in our daily life either directly in household and personal care products or indirectly in the industrial processes. The kinetics of the interaction of glycyl-DL-aspartic acid (Gly-DL-Asp) with ninhydrin has been investigated spectrophotometrically in aqueous and organic-solvent media in the absence and presence of cationic surfactant of tetradecyltrimethylammonium bromide (TTAB). The study was carried out under different experimental conditions. The first and fractional order-rate were observed for [Gly-DL-Asp] and [ninhydrin], respectively. The reaction was enhanced about four-fold by TTAB micelles. The effect of organic solvents was studied at a constant concentration of TTAB and showed an increase in the absorbance as well as the rate constant for the formation of product (Ruhemann's purple). The results obtained in micellar media are treated quantitatively in terms of pseudo-phase and Piszkiewicz cooperativity models. The Arrhenius and Eyring equations are valid for the reaction over the range of temperatures used and different activation parameters (Ea, ∆H#, ∆S#, and ∆G#) have been evaluated.

Keywords: glycyl-DL-aspartic acid, ninhydrin, organic solvents, TTAB

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Authors: Rungsinee Sothornvit, Pattrathip Rodsamran

Abstract:

Rice stubble consists of a high content of cellulose and can be synthesized as a cellulose derivative such as carboxymethyl cellulose (CMC) to value added products from agricultural waste. Therefore, the synthesis conditions and characterization the properties of CMC from rice stubble (CMCr) were investigated. Hemicellulose and lignin were first removed from the rice stubble using 10% NaOH at 55 C for 3 h and 5% NaOCl at 75 C for 15 min, respectively. Rice stubble cellulose was swollen in 30% NaOH and isopropanol as a solvent. The content of chloroacetic acid (5–7 g in 5 g of alkali cellulose), reaction temperature (50 and 70 C) and time (180, 270 and 360 min) were explored to obtain CMC. It was found that synthesis conditions did not affect significantly on moisture content and pH of CMCr. The best quality of CMCr was synthesized by using 7 g of chloroacetic acid and reacted at 50 C for 180 min based on 5 g of rice stubble cellulose. Degree of substitution (DS), viscosity and purity of CMCr were 0.64, 36.03 cP and 90.18 %, respectively. Furthermore, Fourier transform infrared (FT–IR) spectroscopy confirmed the presence of carboxymethyl substituents. CMCr was categorized in commercial scale as a low viscosity material and it can be used as film forming packaging materials for food and pharmaceutical product applications.

Keywords: rice stubble, cellulose, carboxymethyl cellulose, degree of substitution, purity

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