Search results for: high-performance liquid chromatography

Authors: David J. Chato, John B. McQuillen, Brian J.Motil, David F. Chao, Nengli Zhang

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In order to better understand the performance of screen channel liquid acquisition devices (LADs) in liquid oxygen (LOX), a computational fluid dynamics (CFD) simulation of LOX passing through a LAD screen channel was conducted. In the simulation, the screen is taken as a 'porous jump' where the pressure drop across the screen depends on the incoming velocity and is formulated by Δp = Av + Bv2 . The CFD simulation reveals the importance of the pressure losses due to the flow entering from across the screen and impacting and merging with the channel flow and the vortices in the channel to the cumulative flow resistance. In fact, both the flow resistance of flows impact and mergence and the resistance created by vortices are much larger than the friction and dynamic pressure losses in the channel and are comparable to the flow resistance across the screen. Therefore, these resistances in the channel must be considered as part of the evaluation for the LAD channel performance. For proper operation of a LAD in LOX these resistances must be less than the bubble point pressure for the screen channel in LOX. The simulation also presents the pressure and velocity distributions within the LAD screen channel, expanding the understanding of the fluid flow characteristics within the channel.

Keywords: Liquid acquisition devices, liquid oxygen, pressure drop, vortex, bubble point, flow rate limitation.

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Authors: Sheikh Muhammad Azam, Masood-ur-Rehman, Adnan Khalid Bhatti, Nadeem Daudpota

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Very Large and/or computationally complex optimization problems sometimes require parallel or highperformance computing for achieving a reasonable time for computation. One of the most popular and most complicate problems of this family is “Traveling Salesman Problem". In this paper we have introduced a Branch & Bound based algorithm for the solution of such complicated problems. The main focus of the algorithm is to solve the “symmetric traveling salesman problem". We reviewed some of already available algorithms and felt that there is need of new algorithm which should give optimal solution or near to the optimal solution. On the basis of the use of logarithmic sampling, it was found that the proposed algorithm produced a relatively optimal solution for the problem and results excellent performance as compared with the traditional algorithms of this series.

Keywords: Parallel execution, symmetric traveling salesman problem, branch and bound algorithm, logarithmic sampling.

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Authors: V. Hernandez-Perez, M. Abdulkadir, B. J. Azzopardi

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In this work, new experimental data for slugging frequency in inclined gas-liquid flow are reported, and a new correlation is proposed. Scale experiments were carried out using a mixture of air and water in a 6 m long pipe. Two different pipe diameters were used, namely, 38 and 67 mm. The data were taken with capacitance type sensors at a data acquisition frequency of 200 Hz over an interval of 60 seconds. For the range of flow conditions studied, the liquid superficial velocity is observed to influence the frequency strongly. A comparison of the present data with correlations available in the literature reveals a lack of agreement. A new correlation for slug frequency has been proposed for the inclined flow, which represents the main contribution of this work.

Keywords: slug frequency, inclined flow

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Authors: Mohammad Nasri, Hossein Mirshekarpour

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We aimed to investigate how can target and optimize pulmonary delivery distribution by changing physicochemical characteristics of instilled liquid.Therefore, we created a new liquids group: a. eligible for desired distribution within lung because of assorted physicochemical characteristics b. capable of being augmented with a broad range of chemicals inertly c. no interference on respiratory function d. compatible with airway surface liquid We developed forty types of new liquid,were composed of Carboxymethylcellulose sodium,Glycerin and different types of Polysorbates.Viscosity was measured using a Programmable Rheometer and surface tension by KRUSS Tensiometer.We subsequently examined the liquids and delivery protocols by simple and branched glass capillary tube models of airways.Eventually,we explored pulmonary distribution of liquids being augmented with technetium-99m in mechanically ventilated rabbits.We used a single head large field of view gamma camera.Kinematic viscosity between 0.265Stokes and 0.289Stokes,density between 1g/cm3 and 1.5g/cm3 and surface tension between 25dyn/cm and 35dyn/cm were the most acceptable.

Keywords: Pulmonary delivery, Liquid instillation into airway, Physicochemical characteristics, Optimal distribution.

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Authors: S. Forkapic, J. Nikolov, N. Todorovic, D. Mrdja, I. Bikit

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Tritium activity concentration in Danube river water in Serbia has been determinate using a liquid scintillation counter Quantulus 1220. During December 2010, water samples were taken along the entire course of Danube through Serbia, from Hungarian- Serbian to Romanian-Serbian border. This investigation is very important because of the nearness of nuclear reactor Paks in Hungary. Sample preparation was performed by standard test method using Optiphase HiSafe 3 scintillation cocktail. We used a rapid method for the preparation of environmental samples, without electrolytic enrichment.

Keywords: detection limit, liquid scintillation counter, low-leveltritium analysis, monitoring.

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Authors: Congmin Z. Xie, Terry Healy, Peter Robinson, Kevin Stewart

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An HPLC-UV analytical method was developed to determine ethylenediaminetetraacetic acid (EDTA) in dairy wastewater and surface water. The optimizing separation was achieved by reversed–phase ion-pair liquid chromatography on a C18 column using methanol as mobile phase solvent, tetrabutylammonium bromide as the ion-pair reagent in pH 3.3 formate buffer solution at a flow rate of 0.9 mL min-1 with a UV detector at 265 nm. No interference of Ca, Mg or NO3 - was detected. Method performance was evaluated in terms of linearity, repeatability and reproducibility. The method detection limit was 5 μg L-1. The contents of EDTA in dairy effluents were 72 ~ 261 μg L-1 at a large dairy site. A change of EDTA concentration was observed downstream of the dairy effluent discharge, but this was well under the predicted no effect concentration for aquatic ecosystem.

Keywords: Dairy wastewater, EDTA, HPLC, surface water.

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Authors: John B. McQuillen, David F. Chao, Nancy R. Hall, Brian J. Motil, Nengli Zhang

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Future space vehicles will require the use of non-toxic, cryogenic propellants, because of the performance advantages over the toxic hypergolic propellants and also because of the environmental and handling concerns. A prototypical capillary flow liquid acquisition device (LAD) for cryogenic propellants was fabricated with a mesh screen, covering a rectangular flow channel with a cylindrical outlet tube, and was tested with liquid oxygen (LOX). In order to better understand the performance in various gravity environments and orientations with different submersion depths of the LAD, a series of computational fluid dynamics (CFD) simulations of LOX flow through the LAD screen channel, including horizontally and vertically submersions of the LAD channel assembly at normal gravity environment was conducted. Gravity effects on the flow field in LAD channel are inspected and analyzed through comparing the simulations.

Keywords: Liquid acquisition device, cryogenic propellants, CFD simulation, vertically submerged screen channel, gravity effects.

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Authors: F. Gholami, M. Torabi Angaji, Z. Gholami

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Fischer-Tropsch synthesis is one of the most important catalytic reactions that convert the synthetic gas to light and heavy hydrocarbons. One of the main issues is selecting the type of reactor. The slurry bubble reactor is suitable choice for Fischer- Tropsch synthesis because of its good qualification to transfer heat and mass, high durability of catalyst, low cost maintenance and repair. The more common catalysts for Fischer-Tropsch synthesis are Iron-based and Cobalt-based catalysts, the advantage of these catalysts on each other depends on which type of hydrocarbons we desire to produce. In this study, Fischer-Tropsch synthesis is modeled with Iron and Cobalt catalysts in a slurry bubble reactor considering mass and momentum balance and the hydrodynamic relations effect on the reactor behavior. Profiles of reactant conversion and reactant concentration in gas and liquid phases were determined as the functions of residence time in the reactor. The effects of temperature, pressure, liquid velocity, reactor diameter, catalyst diameter, gasliquid and liquid-solid mass transfer coefficients and kinetic coefficients on the reactant conversion have been studied. With 5% increase of liquid velocity (with Iron catalyst), H2 conversions increase about 6% and CO conversion increase about 4%, With 8% increase of liquid velocity (with Cobalt catalyst), H2 conversions increase about 26% and CO conversion increase about 4%. With 20% increase of gas-liquid mass transfer coefficient (with Iron catalyst), H2 conversions increase about 12% and CO conversion increase about 10% and with Cobalt catalyst H2 conversions increase about 10% and CO conversion increase about 6%. Results show that the process is sensitive to gas-liquid mass transfer coefficient and optimum condition operation occurs in maximum possible liquid velocity. This velocity must be more than minimum fluidization velocity and less than terminal velocity in such a way that avoid catalysts particles from leaving the fluidized bed.

Keywords: Modeling, Fischer-Tropsch Synthesis, Slurry Bubble Column Reactor.

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Authors: Zhazgul Kelgenbaeva, Emil Omurzak, Saadat Sulaimankulova, Tsutomu Mashimo

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Spherical shaped magnetite (Fe3O4) and Au@Fe3O4 nanoparticles were successfully synthesized from Fe electrodes immersed in water with CTAB surfactant and HAuCl4 solution using simple method-pulsed plasma in liquid, without the use of dopants or special conditions for stabilization. Vibrating sample magnetometer indicated ferromagnetic behavior of particles at room temperature with coercivity and saturation magnetization of (Hc=105 Oe, Ms=6.83 emu/g) for Fe3O4 and (Hc=175, Ms=3.56emu/g) for Au@Fe3O4 nanoparticles. Structure and morphology of nanoparticles were characterized by X-ray Diffraction analysis and HR-TEM measurements. The cytotoxicity of nanoparticles was indicated using a XTT assay to be very low (cell viability: 98-89% with Fe3O4 and 99-91% for Au@Fe3O4 NPs).

Keywords: Magnetite, Gold coated magnetite, Nanoparticles, Pulsed Plasma in Liquid, Cytotoxicity.

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Authors: P.Ramanathan, P.T.Vanathi

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Parallel Prefix addition is a technique for improving the speed of binary addition. Due to continuing integrating intensity and the growing needs of portable devices, low-power and highperformance designs are of prime importance. The classical parallel prefix adder structures presented in the literature over the years optimize for logic depth, area, fan-out and interconnect count of logic circuits. In this paper, a new architecture for performing 8-bit, 16-bit and 32-bit Parallel Prefix addition is proposed. The proposed prefix adder structures is compared with several classical adders of same bit width in terms of power, delay and number of computational nodes. The results reveal that the proposed structures have the least power delay product when compared with its peer existing Prefix adder structures. Tanner EDA tool was used for simulating the adder designs in the TSMC 180 nm and TSMC 130 nm technologies.

Keywords: Parallel Prefix Adder (PPA), Dot operator, Semi-Dotoperator, Complementary Metal Oxide Semiconductor (CMOS), Odd-dot operator, Even-dot operator, Odd-semi-dot operator andEven-semi-dot operator.

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Authors: B. Gopi, N. Naga Krishna, K. Venkateswarlu, K. Sivaprasad

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An effect of rolling temperature on the mechanical properties and microstructural evolution of an Al-Mg-Si alloy was studied. The material was rolled up to a true strain of ~0.7 at three different temperatures viz; room temperature, liquid propanol and liquid nitrogen. The liquid nitrogen rolled sample exhibited superior properties with a yield and tensile strength of 332 MPa and 364 MPa, respectively, with a reasonably good ductility of ~9%. The liquid nitrogen rolled sample showed around 54 MPa increase in tensile strength without much reduction in the ductility as compared to the as received T6 condition alloy. The microstructural details revealed equiaxed grains in the annealed and solutionized sample and elongated grains in the rolled samples. In addition, the cryorolled samples exhibited fine grain structure compared to the room temperature rolled samples.

Keywords: Al-Mg-Si alloy, cryorolling, tensile properties, ultra-fine grain structure.

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Authors: Konstantza Tonova, Ivan Svinyarov, Milen G. Bogdanov

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Ionic liquids consisting of a phosphonium cationic moiety and a saccharinate anion are synthesized and compared with their precursors, phosphonium chlorides, in reference to their extraction efficiency towards L-lactic acid. On the base of measurements of the acid and the water partitioning in the equilibrium biphasic systems, the molar ratios between acid, water and ionic liquid are estimated which allows to deduce the lactic acid extractive pathway. The effect of a salting-out addition that strengthens hydrophobicity in both phases is studied in view to reveal the best biphasic system with respect to IL low toxicity and high extraction efficiency.

Keywords: Biphasic system, Extraction, Ionic liquids, Lactic acid.

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Authors: P. Adibi, M. R. Ansari, S. Jafari, B. Habibpour, E. Salimi

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In this paper, the effect of gas and liquid superficial inlet velocities and for the first time the effect of liquid holdup on slug initiation position are studied experimentally. Empirical correlations are also presented based on the obtained results. The tests are conducted for three liquid holdups in a long horizontal channel with dimensions of 5cm10cm and 36m length. Usl and Usg rated as to 0.11m/s to 0.56m/s and 1.88m/s to 13m/s, respectively. The obtained results show that as αl=0.25, slug initiation position is increasing monotonically with Usl and Usg. During αl=0.50, slug initiation position is almost constant. For αl=0.75, slug initiation position is decreasing monotonically with Usl and Usg. In the case of equal void fraction of phases, generated slugs are weakly (low pressure). However, for the unequal void fraction of phases strong slugs (high pressure) are formed.

Keywords: Liquid holdup, Long horizontal channel, Slug initiation position, Superficial inlet velocity.

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Authors: Herti Utami, Sutijan, Roto, Wahyudi Budi Sediawan

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α-Pinene is the main component of the most turpentine oils. The hydration of α-pinene with acid catalysts leads to a complex mixture of monoterpenes. In order to obtain more valuable products, the α-pinene in the turpentine can be hydrated in dilute mineral acid solutions to produce α-terpineol. The design of separation processes requires information on phase equilibrium and related thermodynamic properties. This paper reports the results of study on liquid-liquid equilibrium (LLE) of system containing α- pinene + water and α-terpineol + water. Binary LLE for α-pinene + water system, and α-terpineol + water systems were determined by experiment at 301K and atmospheric pressure. The two component mixture was stirred for about 30min, then the mixture was left for about 2h for complete phase separation. The composition of both phases was analyzed by using a Gas Chromatograph. The experimental data were correlated by considering both NRTL and UNIQUAC activity coefficient models. The LLE data for the system of α-pinene + water and α-terpineol + water were correlated successfully by the NRTL model. The experimental data were not satisfactorily fitted by the UNIQUAC model. The NRTL model (α =0.3) correlates the LLE data for the system of α-pinene + water at 301K with RMSD of 0.0404%. And the NRTL model (α =0.61) at 301K with RMSD of 0.0058 %. The NRTL model (α =0.3) correlates the LLE data for the system of α- terpineol + water at 301K with RMSD of 0.1487% and the NRTL model (α =0.6) at 301K with RMSD of 0.0032%, between the experimental and calculated mole fractions.

Keywords: α-Pinene, α-Terpineol, Liquid-liquid Equilibrium, NRTL model, UNIQUAC model

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Authors: Gaurav Bhanjana, Ganga Ram Chaudhary, Sandeep Kumar, Neeraj Dilbaghi

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Main sources of endocrine disrupting compounds in the ecosystem are hormones, pesticides, phthalates, flame retardants, dioxins, personal-care products, coplanar polychlorinated biphenyls (PCBs), bisphenol A, and parabens. These endocrine disrupting compounds are responsible for learning disabilities, brain development problems, deformations of the body, cancer, reproductive abnormalities in females and decreased sperm count in human males. Although discharge of these chemical compounds into the environment cannot be stopped, yet their amount can be retarded through proper evaluation and detection techniques. The available techniques for determination of these endocrine disrupting compounds mainly include high performance liquid chromatography (HPLC), mass spectroscopy (MS) and gas chromatography-mass spectrometry (GC–MS). These techniques are accurate and reliable but have certain limitations like need of skilled personnel, time consuming, interference and requirement of pretreatment steps. Moreover, these techniques are laboratory bound and sample is required in large amount for analysis. In view of above facts, new methods for detection of endocrine disrupting compounds should be devised that promise high specificity, ultra sensitivity, cost effective, efficient and easy-to-operate procedure. Nowadays, electrochemical sensors/biosensors modified with nanomaterials are gaining high attention among researchers. Bioelement present in this system makes the developed sensors selective towards analyte of interest. Nanomaterials provide large surface area, high electron communication feature, enhanced catalytic activity and possibilities of chemical modifications. In most of the cases, nanomaterials also serve as an electron mediator or electrocatalyst for some analytes.

Keywords: Sensors, endocrine disruptors, nanoparticles, electrochemical, microscopy.

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Authors: Mateen Abbas, Abdul Muqeet Khan, Muhammad Rafique Asi, Javed Akhtar

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Mycotoxin (aflatoxins) contamination of peanuts is a great concern for human health. A total of 72 samples of unripe, roasted, and salty peanuts were collected randomly from Pothohar plateau of Pakistan for the assessment of aflatoxin. Samples were dried, ground and extracted by acetonitrile (84%). The filtered extracts were cleaned up by MycoSep-226 and analyzed by high performance liquid chromatography with flourescence detector. Quantification limit of Aflatoxin was 1 μg/kg and 70% Recovery was observed in spiked samples in the range 1–10 μg/kg. The screening of mycotoxins indicated that aflatoxins were present in most of the samples being detected in 82%, in concentrations from 14.25 μg/kg to 98.80 μg/kg. Optimal conditions for mycotoxin production and fungal growth are frequently found in the crop fields as well as in store houses. Human exposure of such toxin can be controlled by pointed out such awareness and implemented the regulations.

Keywords: Aflatoxin, HPLC, Pakistan, Peanuts, Punjab

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Authors: M. O. Bayram, H. B. Gencdal, N. O. Fercan, B. Basbug

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Liquid limit, which is used as a measure of soil strength, can be detected by Casagrande and fall-cone testing methods. The two methods majorly diverge from each other in terms of operator dependency. The Casagrande method that is applied according to ASTM D4318-17 standards may give misleading results, especially if the calibration process is not performed well. In this study, to reveal the effect of calibration for drop height and amount of soil paste placement in the Casagrande cup, a series of tests were carried out by multipoint method as it is specified in the ASTM standards. The tests include the combination of 6 mm, 8 mm, 10 mm, and 12 mm drop heights and under-filled, half-filled, and full-filled Casagrande cups by kaolin samples. It was observed that during successive tests, the drop height of the cup deteriorated; hence the device was recalibrated before and after each test to provide the accuracy of the results. Besides, the tests by under-filled and full-filled samples for higher drop heights revealed lower liquid limit values than the lower drop heights revealed. For the half-filled samples, it was clearly seen that the liquid limit values did not change at all as the drop height increased, and this explains the function of standard specifications.

Keywords: Calibration, Casagrande cup method, drop height, kaolin, liquid limit, placing form.

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Authors: Ji Young Song, Soo Jung Hu, Hyunjin Joo, Joung Boon Hwang, Mi Ok Kim, Shin Jung Kang, Dae Hyun Cho

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Multi-residue analysis method for penicillins was developed and validated in bovine muscle, chicken, milk, and flatfish. Detection was based on liquid chromatography tandem mass spectrometry (LC/MS/MS). The developed method was validated for specificity, precision, recovery, and linearity. The analytes were extracted with 80% acetonitrile and clean-up by a single reversed-phase solid-phase extraction step. Six penicillins presented recoveries higher than 76% with the exception of Amoxicillin (59.7%). Relative standard deviations (RSDs) were not more than 10%. LOQs values ranged from 0.1 and to 4.5 ug/kg. The method was applied to 128 real samples. Benzylpenicillin was detected in 15 samples and Cloxacillin was detected in 7 samples. Oxacillin was detected in 2 samples. But the detected levels were under the MRL levels for penicillins in samples.

Keywords: Penicillins, livestock product, Multi-residue analysis, LC/MS/MS

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Authors: Seyed Abolhasan Naeini, Mohammad Hossein Zade, E. Izadi, M. Hossein Zade

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The different seismic behavior of liquid storage tanks rather than conventional structures makes their responses more complicated. Uplifting and excessive settlement due to liquid sloshing are the most frequent damages in cylindrical liquid tanks after shell bucking failure modes. As a matter of fact, uses of liquid storage tanks because of the simple construction on compact layer of soil as a foundation are very conventional, but in some cases need to retrofit are essential. The tank seismic behavior can be improved by modifying dynamic characteristic of tank with verifying seismic loads as well as retrofitting and improving base ground. This paper focuses on a typical steel tank on loose, medium and stiff sandy soil and describes an evaluation of displacement of the tank before and after retrofitting. The Abaqus program was selected for its ability to include shell and structural steel elements, soil-structure interaction, and geometrical nonlinearities and contact type elements. The result shows considerable decreasing in settlement and uplifting in the case of retrofitted tank. Also, by increasing shear strength parameter of soil, the performance of the liquid storage tank under the case of seismic load increased.

Keywords: Steel tank, soil-structure, sandy soil, seismic load.

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Authors: Weiwei Shan, Wenjing Ding, Juan Ning, Chao He, Zijuan Wang

Abstract:

Gravity circulation loop for the cryopumps of the space simulator is introduced, and two phase mathematic model of flow heat transfer is analyzed as well. Based on this model, the liquid nitrogen (LN₂) gravity circulation loop including its equipment and layout is designed and has served as LN₂ feeding system for cryopumps in one large space simulator. With the help of control software and human machine interface, this system can be operated flexibly, simply, and automatically under four conditions. When running this system, the results show that the cryopumps can be cooled down and maintained under the required temperature, 120 K.

Keywords: Cryopumps, gravity circulation loop, liquid nitrogen, two-phase.

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Authors: Kittiphop Promdee, Tharapong Vitidsant

Abstract:

Continuous pyrolysis of Cogongrass by control temperature in the novel pyrolysis reactor were conducted at three difference temperatures 400, 450 and 500°C. Preliminary calculate of the product yields founded the liquid yield of Cogongrass was highest of 41.45 %, at 500 oC. Indicated that the liquid yield from Cogongrass had good received yields because it gave over 40 % and its produced more liquid than that solid and gas. The compounds detected in bio-oil from Cogongrass showed the functional group, especially; Phenol, Phenol, 2,5-dimethyl, Phenol, 3-methyl, 2- methyl-1,3-oxathiofane, Benzene,1-ethyl-4-methoxy, 2-Cyclopenten- 1-one,2,3-dimethyl, 2- Cyclopenten-1- one, 3-Methyl.

Keywords: Pyrolysis, Cogongrass, Product Yields, Chemical Compounds, Twin Screw Feeder.

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Authors: Rutanachai Thaipratum

Abstract:

The mechanism of abiotic stress tolerance is crucial for plants to survive in harsh condition and the knowledge of this mechanism can be use to solve the problem of declining productivity of plants or crops around the world. However in-depth description is still unclear and it is argued, in particular that there is a relationship between high salinity tolerance and the ability to tolerate high light condition. In this study, Dunaliella salina, which can withstand high salt was used as a model. Chlorophyll fluorometer for nonphotochemical quenching (NPQ) measurement and high-performance liquid chromatography for pigment determination was used. The results show that NPQ value and the amount of pigment were increased along with the levels of salinity. However, it establish a clear relationship between high salt and high light but the further study to optimized the solutions mentioned above is still required.

Keywords: Abiotic stress tolerance, Dunaliella salina, Nonphotochemical quenching, Zeaxanthin.

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Authors: M. Javadzadeh, H. Khoshsima

Abstract:

In this article, we present a layout printing way for producing Fresnel zone on 1294-1b doped liquid crystal with Methyl-Red azo dye. We made a Fresnel zone mask with 25 zones and radius of 5 mm using lithography technique. With layout printing way, we recorded mask’s pattern on cell with λ=532 nm solid-state diode pump laser. By recording Fresnel zone pattern on cell and making Fresnel pattern on the surface of cell, odd and even zones, will form. The printed pattern, because of Azo dye’s photoisomerization, was permanent. Experimentally, we saw focal length tunability from 32 cm to 43 cm.

Keywords: Liquid crystal, lens, Fresnel zone, diffraction, Fresnel lens.

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Authors: S. Mousavian, A. Abedianpour, A. Khanmohammadi, S. Hematian, Gh. Eidi Veisi

Abstract:

Ionic liquids are finding a wide range of applications from reaction media to separations and materials processing. In these applications, Vapor–Liquid equilibrium (VLE) is the most important one. VLE for six systems at 353 K and activity coefficients at infinite dilution [(γ)_i^∞] for various solutes (alkanes, alkenes, cycloalkanes, cycloalkenes, aromatics, alcohols, ketones, esters, ethers, and water) in the ionic liquids (1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide [EMIM][BTI], 1-hexyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide [HMIM][BTI], 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [OMIM][BTI], and 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide [BMPYR][BTI]) have been used to train neural networks in the temperature range from (303 to 333) K. Densities of the ionic liquids, Hildebrant constant of substances, and temperature were selected as input of neural networks. The networks with different hidden layers were examined. Networks with seven neurons in one hidden layer have minimum error and good agreement with experimental data.

Keywords: Ionic liquid, Neural networks, VLE, Dilute solution.

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Authors: Mazin Alqhazo, Ayat Bani Rashaid

Abstract:

This study examines the levels of dopamine and serotonin in blood samples of children who stutter compared with normal fluent speakers. Blood specimens from 50 children who stutter (6 females, 44 males) and 50 normal children matched age and gender were collected for the purpose of the current study. The concentrations of dopamine and serotonin were measured using the 1100 series high-performance liquid chromatography coupled with ultraviolet detector instrument (HPLC-UV). It was revealed that dopamine level in the blood samples of stuttering group and fluent group was not significant (P = 0.769), whereas the level of serotonin was significantly higher in the blood samples of stuttering group than the blood samples of fluent normal group (P = 0.015). It is concluded that serotonin blockers could be used in future studies to evaluate its role as a medication for the treatment of stuttering.

Keywords: Dopamine, serotonin, stuttering, fluent.

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Authors: Mário A. R. Talaia

Abstract:

As it is known, buoyancy and drag forces rule bubble's rise velocity in a liquid column. These forces are strongly dependent on fluid properties, gravity as well as equivalent's diameter. This study reports a set of bubble rising velocity experiments in a liquid column using water or glycerol. Several records of terminal velocity were obtained. The results show that bubble's rise terminal velocity is strongly dependent on dynamic viscosity effect. The data set allowed to have some terminal velocities data interval of 8.0 ? 32.9 cm/s with Reynolds number interval 1.3 -7490. The bubble's movement was recorded with a video camera. The main goal is to present an original set data and results that will be discussed based on two-phase flow's theory. It will also discussed, the prediction of terminal velocity of a single bubble in liquid, as well as the range of its applicability. In conclusion, this study presents general expressions for the determination of the terminal velocity of isolated gas bubbles of a Reynolds number range, when the fluid proprieties are known.

Keywords: Bubbles, terminal velocity, two phase-flow, vertical column.

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Authors: Fariba Tadayon, Elmira Hassanlou, Hasan Bagheri, Mostafa Jafarian

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Heavy metals are released into water, plants, soil, and food by natural and human activities. Lead has toxic roles in the human body and may cause serious problems even in low concentrations, since it may have several adverse effects on human. Therefore, determination of lead in different samples is an important procedure in the studies of environmental pollution. In this work, an ultrasonic assisted-ionic liquid based-liquid-liquid microextraction (UA-IL-DLLME) procedure for the determination of lead in zucchini, pomegranate, and lettuce has been established and developed by using flame atomic absorption spectrometer (FAAS). For UA-IL-DLLME procedure, 10 mL of the sample solution containing Pb2+ was adjusted to pH=5 in a glass test tube with a conical bottom; then, 120 μL of 1-Hexyl-3-methylimidazolium hexafluoro phosphate (CMIM)(PF6) was rapidly injected into the sample solution with a microsyringe. After that, the resulting cloudy mixture was treated by ultrasonic for 5 min, then the separation of two phases was obtained by centrifugation for 5 min at 3000 rpm and IL-phase diluted with 1 cc ethanol, and the analytes were determined by FAAS. The effect of different experimental parameters in the extraction step including: ionic liquid volume, sonication time and pH was studied and optimized simultaneously by using Response Surface Methodology (RSM) employing a central composite design (CCD). The optimal conditions were determined to be an ionic liquid volume of 120 μL, sonication time of 5 min, and pH=5. The linear ranges of the calibration curve for the determination by FAAS of lead were 0.1-4 ppm with R2=0.992. Under optimized conditions, the limit of detection (LOD) for lead was 0.062 μg.mL-1, the enrichment factor (EF) was 93, and the relative standard deviation (RSD) for lead was calculated as 2.29%. The levels of lead for pomegranate, zucchini, and lettuce were calculated as 2.88 μg.g-1, 1.54 μg.g-1, 2.18 μg.g-1, respectively. Therefore, this method has been successfully applied for the analysis of the content of lead in different food samples by FAAS.

Keywords: Dispersive liquid-liquid microextraction, Central composite design, Food samples, Flame atomic absorption spectrometry.

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Authors: F. R. Sultanov Ch. Daulbayev, B. Bakbolat, Z. A. Mansurov, A. A. Zhurintaeva, R. I. Gadilshina, A. B. Dugali

Abstract:

Both hydrophilic-oleophobic and hydrophobic-oleophilic membranes were obtained by coating of the substrate of membranes, presented by stainless steel meshes with various dimensions of their openings, with a composition that forms the special type of their surface wettability via spray-coating method. The surface morphology of resulting membranes was studied using SEM, the type of their wettability was identified by measuring the contact angle between the surface of membrane and a drop of studied liquid (water or organic liquid) and efficiency of continuous separation of water and organic liquid was studied on self-assembled setup.

Keywords: Membrane, stainless steel mesh, oleophobicity, hydrophobicity, separation, water, organic liquids.

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Authors: J.J. Cooke, S. Gu, L.M. Armstrong, K.H. Luo

Abstract:

Carbon Capture & Storage (CCS) is one of the various methods that can be used to reduce the carbon footprint of the energy sector. This paper focuses on the absorption of CO2 from flue gas using packed columns, whose efficiency is highly dependent on the structure of the liquid films within the column. To study the characteristics of liquid films a CFD solver, OpenFOAM is utilised to solve two-phase, isothermal film flow using the volume-of-fluid (VOF) method. The model was validated using existing experimental data and the Nusselt theory. It was found that smaller plate inclination angles, with respect to the horizontal plane, resulted in larger wetted areas on smooth plates. However, only a slight improvement in the wetted area was observed. Simulations were also performed using a ridged plate and it was observed that these surface textures significantly increase the wetted area of the plate. This was mainly attributed to the channelling effect of the ridges, which helped to oppose the surface tension forces trying to minimise the surface area. Rivulet formations on the ridged plate were also flattened out and spread across a larger proportion of the plate width.

Keywords: CCS, liquid film flow, packed columns, wetted area

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Authors: S.H. Khoon, G.I. Issabayeva, L.W. Lee

Abstract:

Air quality in Setapak district of Kuala Lumpur was studied by analysing the rainwater chemical composition using ion chromatography method. Twelve sampling sites were selected and 120 rainwater samples were collected in the period of 10 weeks. The results of this study were compared to the earlier published data and the evaluation showed that the NO3 - ion concentration increased from 0.41 to 3.32 ppm, while SO4 2- ion concentration increased from 0.39 to 3.26 ppm over the past two decades that is mostly due to rapid urban development of the city. However, it was found that the chemical composition for both residential and industrial areas does not have significant difference. Most of the rainwater samples showed alkaline pH (pH > 5.6). The possible factors for such alkaline pH in rainwater samples are assumed to be the marine sources, biomass burning and alkaline character of soil particles.

Keywords: acid deposition; atmospheric pollution; deposition fluxes; trajectories

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