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Sample records for comparative kinetics study

  1. A Comparative Kinetic Study of Acidic Hydrolysis of Wastes ...

    African Journals Online (AJOL)

    A Comparative Kinetic Study of Acidic Hydrolysis of Wastes Cellulose from Agricultural Derived Biomass. ... fuels and chemicals offers potential economical, environmental and strategic ... Keywords: Agricultural wastes; cellulose; acid hydrolysis; first-order rate kinetics; activation energy, Arrhenius equation ... Article Metrics.

  2. A comparative kinetic study of SNCR process using ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Javed, M. Tayyeb; Ahmed, Z.; Ibrahim, M. Asim; Irfan, N.

    2008-07-01

    The paper presents comparative kinetic modelling of nitrogen oxides (NOx) removal from flue gases by selective non-catalytic reduction process using ammonia as reducing agent. The computer code SENKIN is used in this study with the three published chemical kinetic mechanisms; Zanoelo, Kilpinen and Skreiberg. Kinetic modeling was performed for an isothermal plug flow reactor at atmospheric pressure so as to compare it with the experimental results. A 500 ppm NOx background in the flue gas is considered and kept constant throughout the investigation. The ammonia performance was modeled in the range of 750 to 1250{sup o}C using the molar ratios NH{sub 3}/NOx from 0.25 to 3.0 and residence times up to 1.5 seconds. The modeling using all the mechanisms exhibits and confirms a temperature window of NOx reduction with ammonia. It was observed that 80% of NOx reduction efficiency could be achieved if the flue gas is given 300 msec to react with ammonia, while it is passing through a section within a temperature range of 910 to 1060{sup o}C (Kilpinen mechanism) or within a temperature range of 925 to 1030{sup o}C (Zanoelo mechanism) or within a temperature range of 890 to 1090{sup o}C (Skreiberg mechanism). 20 refs., 6 figs.

  3. A comparative study of kinetics of nuclear reactors

    Directory of Open Access Journals (Sweden)

    Obaidurrahman Khalilurrahman

    2009-01-01

    Full Text Available The paper deals with the study of reactivity initiated transients to investigate major differences in the kinetics behavior of various reactor systems under different operating conditions. The article also states guidelines to determine the safety limits on reactivity insertion rates. Three systems, light water reactors (pressurized water reactors, heavy water reactors (pressurized heavy water reactors, and fast breeder reactors are considered for the sake of analysis. The upper safe limits for reactivity insertion rate in these reactor systems are determined. The analyses of transients are performed by a point kinetics computer code, PKOK. A simple but accurate method for accounting total reactivity feedback in kinetics calculations is suggested and used. Parameters governing the kinetics behavior of the core are studied under different core states. A few guidelines are discussed to project the possible kinetics trends in the next generation reactors.

  4. Comparative studies of the pyrolytic and kinetic characteristics of maize straw and the seaweed Ulva pertusa.

    Directory of Open Access Journals (Sweden)

    Naihao Ye

    Full Text Available Seaweed has attracted considerable attention as a potential biofuel feedstock. The pyrolytic and kinetic characteristics of maize straw and the seaweed Ulva pertusa were studied and compared using heating rates of 10, 30 and 50°C min(-1 under an inert atmosphere. The activation energy, and pre-exponential factors were calculated by the Flynn-Wall-Ozawa (FWO, Kissinger-Akahira-Sunose (KAS and Popescu methods. The kinetic mechanism was deduced by the Popescu method. The results indicate that there are three stages to the pyrolysis; dehydration, primary devolatilization and residual decomposition. There were significant differences in average activation energy, thermal stability, final residuals and reaction rates between the two materials. The primary devolatilization stage of U. pertusa can be described by the Avramic-Erofeev equation (n=3, whereas that of maize straw can be described by the Mampel Power Law (n=2. The average activation energy of maize straw and U. pertusa were 153.0 and 148.7 KJ mol(-1, respectively. The pyrolysis process of U.pertusa would be easier than maize straw. And co-firing of the two biomass may be require less external heat input and improve process stability. There were minor kinetic compensation effects between the pre-exponential factors and the activation energy.

  5. Comparative study of kinetic and interfacial properties of a novel Rhizopus oryzae lipase and ROL29

    Directory of Open Access Journals (Sweden)

    Ben Salah Riadh

    2007-11-01

    Full Text Available We compared several kinetic and interfacial properties of a lipase from a novel strain of Rhizopus oryzae (ROLw with ROL29 lipase. In contrast to ROL29, ROLw was able to hydrolyze triolein emulsion in the absence of any additive, like bovine serum albumin (BSA. Furthermore, unlike Rhizopus oryzae lipase (ROL29, kinetic study of ROLw lipase shows linear dependency when using tributyrin emulsion as substrate. ROLw can tolerate, more efficiently than ROL29, the accumulation of long-chain free fatty acids at the interface when olive oil emulsion was used as substrate. The critical surface pressure πc of penetration into phosphatidyl choline from egg yolk films was found to be 23 mN/m with ROLw, in contrast to a value of 10 mN/m obtained with ROL29. The effect of calcium ion and synthetic detergent on the two lipases was studied. In contrast to ROL29, ROLw was activated in the presence of 100 lmoles TX-100. No significant difference on the two lipase activity was observed in presence or absence of calcium ion.

  6. Comparative study of thermal inactivation kinetics of Salmonella spp. in peanut butter and peanut butter spread

    Science.gov (United States)

    Peanut butter has been implicated in multi-state outbreaks of salmonellosis in recent years. Studies have shown that Salmonella exhibited increased thermal resistance in peanut butter. However, little is known about the effect of product formulation on the kinetics of survival of Salmonella during...

  7. Comparative study of forward and backward test-kinetic simulation approaches

    CERN Document Server

    Voitcu, Gabriel; Marchand, Richard

    2016-01-01

    In this paper we perform a comparative study of the forward and backward Liouville mapping applied to the modeling of ring-shaped and non-gyrotropic velocity distribution functions of particles injected in a sheared electromagnetic field. The test-kinetic method is used to compute the velocity distribution function in various areas of a proton cloud moving in the vicinity of a region with a sharp transition of the magnetic field and a non-uniform electric field. In the forward approach the velocity distribution function is computed for a two-dimensional spatial bin, while in the backward approach the distribution function is averaged over a spatial bin with the same size as for the forward method and using a two-dimensional trapezoidal integration scheme. It is shown that the two approaches lead to similar results for spatial bins where the velocity distribution function varies smoothly. On the other hand, with bins covering regions of configuration space characterized by sharp spatial gradients of the veloci...

  8. Comparative Kinetic Study of Anaerobic Treatment of Thermally Pretreated Source-Sorted Organic Market Refuse

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    Aritra Das

    2015-01-01

    Full Text Available The present study deals with extensive investigations of the effect of thermal pretreatment on whole-sale market rejects for their biogas production potential. Market reject considered as biomass for this study has been treated at two different temperatures 85°C and 135°C for 8 h each and subjected as feedstock for anaerobic digestion (AD process. The AD process has been operated in the mesophilic range (35–38°C of bacterial growth. Various kinetic models have been used to simulate the experimental data. Kinetic modeling revealed that biogas production rate exhibited better coefficient of determination (R2 in the range of 0.973–0.989 with exponential model for the ascending limb whereas the descending limb resulted in good linear correlation with R2 as 0.911–0.976. Logistic growth model and Gompertz relation simulation of cumulative biogas production resulted in better R2 values in the range of 0.994–0.997 and 0.998–0.999, whereas the R2 values for exponential rise to maximum plots ranged from 0.722 to 0.800.

  9. A comparative kinetic study of thiamphenicol in pre-ruminant lambs and calves.

    Science.gov (United States)

    Mengozzi, G; Intorre, L; Bertini, S; Giorgi, M; Secchiari, P L; Soldani, G

    2002-12-01

    Eight healthy Holstein-Friesian calves and 8 Massese lambs of either sex (10-15-days old) were used to evaluate the pharmacokinetics of thiamphenicol after intravenous (i.v.) and oral (p.o.) administration (30 mg/kg). Plasma concentrations of thiamphenicol were determined by high-performance liquid chromatography on blood samples collected over 24h following treatment. Pharmacokinetic variables of the drug were calculated for both species and after both administration routes. After intravenous administration of thiamphenicol, a rapid distribution phase was followed by a slower elimination phase and, when thiamphenicol was administered p.o., the bioavailability was about 60% in both species. The higher volume of distribution and the longer biological elimination half-lives in pre-ruminant compared with adult animals indicate that thiamphenicol distributes widely into the extravascular compartment of pre-ruminants. Interspecies differences were observed in the kinetic behaviour of thiamphenicol with respect to peak plasma concentration (C(max)), time of peak plasma concentration (T(max)), elimination half-life (T(1/2)) and total clearance (Cl(B)). In conclusion intravenous or oral administration of 30 mg/kg of thiamphenicol provides plasma concentrations higher than minimum effective concentrations inhibiting bacterial growth (MICs) against most pathogens in pre-ruminant lambs and calves.

  10. Comparative Study on the Kinetic Equations of Potassium Release from Soils

    Institute of Scientific and Technical Information of China (English)

    LUXIAO-NAN; LUYUN-FU

    1993-01-01

    Elovich,two-constant,parabolic diffusion,exponential,second-order,first-order and zero-order equations were used to describe the kinetic characteristics of potassium desorption from six paddy soils of Zhejiang Province in a constant electric field (44.4V/cm) of EUF.Results showed that the second-order and Elovich equations could describe the potassium desorption kinetics best,as evidenced by the highest correlation coefficients (r) and the lowest standard errors (SE).The first-order,two-constant and parabolic diffusion equations also described the K desorption kinetics well,as showed by the relatively high correlation coefficients and relatively low standard errors.The zero-order equation did not describe the K desorption satisfactorily with a relatively low correlation coefficient and relatively high standard error.However,the exponential equation could not be used to describe the K desorption kinetics,due to the lowest correlation coefficient and the highest standarderror.

  11. A comparative study of the chemical kinetics of methyl and ethyl propanoate

    KAUST Repository

    Farooq, Aamir

    2014-10-01

    High temperature pyrolysis of methyl propanoate (CH3CH 2C(O)OCH3) and ethyl propanoate (CH3CH 2C(O)OCH2CH3) was studied behind reflected shock waves at temperatures of 1250-1750 K and pressure of 1.5 atm. Species time-histories were recorded for CO, CO2, C2H4, and H2O using laser absorption methods over a test time of 1 ms. Pyrolysis of methyl propanoate (MP) appears to be faster than that of ethyl propanoate (EP) under the present experimental conditions, where CO and CO 2 reach their plateau values faster for MP at a specific temperature and fuel concentration. Higher plateau values are reached for CO in case of MP while the CO2 levels are similar for the two ester fuels. Ethylene production is larger for EP due to the presence of six-centered ring elimination reaction that produces ethylene and propanoic acid. Very little H2O is produced during MP pyrolysis in contrast with appreciable H2O production from EP. Sensitivity and rate-of-production analyses were carried out to identify key reactions that affect the measured species profiles. Previous kinetic mechanisms of Yang et al. (2011) [1,2] and Metcalf et al. (2009, 2007) [3,4] were used as base models and then refined to propose a new MP/EP pyrolysis mechanism. © 2014 Elsevier Ltd. All rights reserved.

  12. A comparative study of ion exchange kinetics in zinc/lead-modified zeolite-clinoptilolite systems.

    Science.gov (United States)

    Trgo, M; Perić, J; Medvidović, N Vukojević

    2006-08-25

    The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t-->t(infinity). The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10(-6)cm(2)/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10(-8)cm(2)/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.

  13. A comparative kinetic and mechanistic study between tetrahydrozoline and naphazoline toward photogenerated reactive oxygen species.

    Science.gov (United States)

    Criado, Susana; García, Norman A

    2010-01-01

    Kinetic and mechanistic aspects of the vitamin B2 (riboflavin [Rf])-sensitized photo-oxidation of the imidazoline derivates (IDs) naphazoline (NPZ) and tetrahydrozoline (THZ) were investigated in aqueous solution. The process appears as important on biomedical grounds, considering that the vitamin is endogenously present in humans, and IDs are active components of ocular medicaments of topical application. Under aerobic visible light irradiation, a complex picture of competitive interactions between sensitizer, substrates and dissolved oxygen takes place: the singlet and triplet ((3)Rf*) excited states of Rf are quenched by the IDs: with IDs concentrations ca. 5.0 mM and 0.02 mM Rf, (3)Rf* is quenched by IDs, in a competitive fashion with dissolved ground state oxygen. Additionally, the reactive oxygen species: O(2)((1)Delta(g)), O(2)(*-), HO(*) and H(2)O(2), generated from (3)Rf* and Rf(*-), were detected with the employment of time-resolved methods or specific scavengers. Oxygen uptake experiments indicate that, for NPZ, only H(2)O(2) was involved in the photo-oxidation. In the case of THZ, O(2)(*-), HO(*) and H(2)O(2) were detected, whereas only HO(*) was unambiguously identified as THZ oxidative agents. Upon direct UV light irradiation NPZ and THZ generate O(2)((1)Delta(g)), with quantum yields of 0.2 (literature value, employed as a reference) and 0.08, respectively, in acetonitrile.

  14. A comparative study of the antioxidant scavenging activity of green tea, black tea and coffee extracts: a kinetic approach.

    Science.gov (United States)

    Anissi, Jaouad; El Hassouni, Mohammed; Ouardaoui, Abdelkrim; Sendide, Khalid

    2014-05-01

    The antioxidant activities of three beverages, coffee, black tea and green tea, along with their major components, were investigated in terms of their reaction with the stable radical 2,2'-diphenyl-2-picrylhydrazyl (DPPH). We used a kinetic approach in parallel with quantification methods based on a fixed end-point to determine the scavenging efficiency of compounds abundant in these beverages during their reaction with DPPH using a stopped-flow spectrophotometer-based method. Ascorbic acid, (+)-catechin, (-)-epigallocatechin, tannic acid, and caffeic acid were selected as model antioxidants to study in coffee, black tea and green tea. We applied a second-order model to demonstrate similarities in the kinetics behavior of beverages and related compounds. Our findings showed the slopes k2(')((mol/L)(-1)s(-1)) and k2max(')((mol/L)(1)s(-1)) exhibited similar and correlated values; we suggest the variation in k2(') as a function of time is more informative about antioxidant properties than reaction with DPPH alone. We also used IC100 to test the reliability of the relative stoichiometry using a new comparative parameter "n", which was calculated as: n=c0DPPHIC100 (mol/L(mol/L)(-1), (mol/L)mlmg(-1) or molg(-1)).

  15. Comparative study of binding constants from Love wave surface acoustic wave and surface plasmon resonance biosensors using kinetic analysis.

    Science.gov (United States)

    Lee, Sangdae; Kim, Yong-Il; Kim, Ki-Bok

    2013-11-01

    Biosensors are used in a variety of fields for early diagnosis of diseases, measurement of toxic contaminants, quick detection of pathogens, and separation of specific proteins or DNA. In this study, we fabricated and evaluated the capability of a high sensitivity Love wave surface acoustic wave (SAW) biosensor. The experimental setup was composed of the fabricated 155-MHz Love wave SAW biosensor, a signal measurement system, a liquid flow system, and a temperature-control system. Subsequently, we measured the lower limit of detection (LOD) of the 155-MHz Love wave SAW biosensor, and calculated the association and dissociation constants between protein G and anti-mouse IgG using kinetic analysis. We compared these results with those obtained using a commercial surface plasmon resonance (SPR) biosensor. We found that the LOD of the SAW biosensor for anti-mouse IgG and mouse IgG was 0.5 and 1 microg/ml, respectively, and the resultant equilibrium association and dissociation constants were similar to the corresponding values obtaining using the commercial SPR biosensor. Thus, we conclude that the fabricated 155-MHz Love wave SAW biosensor exhibited the high sensitivity of the commercial SPR biosensor and was able to analyze the binding properties of the ligand and receptor by kinetic analysis similarly to the commercial SPR biosensor.

  16. COMPARATIVE STUDY ON METAL IONS ADSORPTION ON A LOW COST CARBONACEOUS ADSORBENT KINETIC EQUILIBRIUM AND MECHANISTIC STUDIES

    Directory of Open Access Journals (Sweden)

    S. Arivoli, M. Hema, C. Barathiraja

    2008-01-01

    Full Text Available A carbonaceous adsorbent prepared from an indigenous waste and treated by acid was tested for its efficiency in removing metal ions of Fe(II, Co(II and Ni(II. The process parameters studied included agitation time, initial metal ion concentration, carbon dosage, pH, other ions and temperature. The kinetics of adsorption followed first order reaction equation and the rate was mainly controlled by intraparticle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacity obtained from the Langmuir isotherm plots was found around 28mg/g for all selected metal ions at an initial pH of 6. The temperature variation study showed that the metal ions adsorption is endothermic and spontaneous with increased randomness at the solid solution interface. Significant effect on adsorption was observed on varying pH of the metal ion solutions. The type I and II isotherms obtained, positive H0 values, pH dependent results and desorption of metal ions in mineral acid suggests that the adsorption of metal ions on this type of adsorbent involves both chemisorption and physical adsorption mechanisms.

  17. COMPARATIVE STUDY OF FOOD SUPPLEMENTS USED ON THE ACTIVITY OF KINETIC ENDURANCE CHARAKTER APPLIED AS A CARDIOVASCULAR DISEASES PREVENTION

    OpenAIRE

    DIČE, Michal

    2009-01-01

    The aim of this thesis is to compare food supplements used on the activity of endurance character and their influence on the cardiovascular system. The teoretical part is pursued to the basic food components and their metabolism and to kinetic activities splitting. The practical part gives information about splitting of sports supplements used on the activity of endurance character, their usage and effects. It deals with the question of human organism behaviour during the strain of endurance ...

  18. Mechanistic chemistry of oxidation of balsalazide with acidic chloramine-T and bromamine-T: A comparative spectrophotometric kinetic study

    Indian Academy of Sciences (India)

    Puttaswamy; S Dakshayani

    2014-11-01

    Balsalazide (BSZ) belongs to a class of non-steroidal anti-inflammatory drugs. Kinetics and mechanism of oxidation of BSZ with sodium N-halo-p-toluenesulfonamides viz., chloramine-T(CAT) and bromamine-T(BAT) in HClO4 medium have been spectrophotometrically investigated (max =357nm) at 303 K. Under comparable experimental conditions, reactions with both the oxidants follow a first-order dependence of rate on [BSZ] and fractional-order dependence on each [oxidant] and [HClO4]. Activation parameters and reaction constants have been computed. 2-hydroxy-5-nitroso-benzoic acid and 3-(4-nitroso-benzoylamino)-propionic acid are identified as the oxidation products of BSZ with both CAT and BAT. The rate of oxidation of BSZ is about five-fold faster with BAT than with CAT. Plausible mechanism and related rate law have been deduced for the observed kinetics.

  19. Comparative Studies on Phosphorus Uptake and Growth Kinetics of the Microalga Tetraselmis subcordiformis and the Macroalga Ulva pertusa

    Institute of Scientific and Technical Information of China (English)

    NAN Chunrong; DONG Shuanglin

    2004-01-01

    Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate (Vspm) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.

  20. Comparative studies on phosphorus uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa

    Science.gov (United States)

    Nan, Chunrong; Dong, Shuanglin

    2004-04-01

    Short-term uptake experiments and long-term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate ( V {m/sp}) and the maximal growth efficiency (β), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.

  1. Comparing adsorption activity of raw Sepiolite and CTAB modified Sepiolite: kinetic and adsorption study for removal of Hg+

    Directory of Open Access Journals (Sweden)

    Ali Ġmran Vaġzoğullar

    2015-12-01

    Full Text Available In our study adsorption of Hg+2 ions from water solutions on Sepiolite (Sep and Modified Sepiolite (MSep with cationic surfactants namely cetyl trimethyl ammonium bromide CTAB was investigated. Different parameters were used to investigate such as contact time, pH and adsorbent dosage. The adsorption capacity of MSep and Sep was examined. Both particles were characterized with FTIR spectrum. According to the our results the equilibrium adsorption data corresponded to the Langmuir isotherm and qmax was 54,7 mg/g and 104,1 mg/g for Sep and MSep respectively. Kinetic parameters showed that pseudo-second-order adsorption kinetic model was the best model than the pseudo-first-order. MSep is more active adsorbent than Sep and it can be the best alternative adsorbent for removing of heavy metal from industrial waste water. In addition MSep can be used as adsorbent for removal of nonpolar toxic organic molecules, because sepiolite surface can be converted from hydrophilic form to hydrophobic form by CTAB resulting in increased the adsorption capacity.International Journal of Environment Vol.4(4 2015: 19-31

  2. Comparative study of electrochemical oxidation of herbicide 2,4,5-T: Kinetics, parametric optimization and mineralization pathway

    Directory of Open Access Journals (Sweden)

    Hicham Zazou

    2017-01-01

    Full Text Available Oxidative degradation of herbicide 2,4,5-T was studied by electrochemical advanced oxidation processes anodic oxidation and electro-Fenton (EF using Pt/carbon felt and BDD/carbon felt cells. The effect of main operating parameters on oxidation of 2,4,5-T and mineralization of its aqueous solution were investigated. The rate constant for oxidation of 2,4,5-T by ·≡OH was determined as (3.7 ± 0.2 × 109 M−1 s−1 using competition kinetics method. The EF process with BDD anode was shown to be very efficient reaching 94% mineralization in 3 h treatment. Based on identified aromatic intermediates, short-chain carboxylic acids, released inorganic ions and total organic carbon removal measurements, a plausible oxidation pathway for mineralization of 2,4,5-T by hydroxyl radical was proposed. In addition, the evolution of solution toxicity during treatment was monitored by Microtox method showing the formation of toxic aromatic/cyclic intermediates. The results showed also that EF process was able to remove efficiently toxic intermediates and consequently solution toxicity.

  3. COMPARATIVE KINETICS STUDY OF THE THERMAL AND THERMO-OXIDATIVE DEGRADATION OF A POLYSTYRENE-CLAY NANOCOMPOZITE BY TGA AND DSC

    Directory of Open Access Journals (Sweden)

    Ion Dranca

    2010-12-01

    Full Text Available The methods of thermogravimetry (TGA and differential scanning calorimetry (DSC have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS and a PS-clay nanocomposite. An advanced isoconversional method has been applied for kinertic analysis. Introduction of the clay phase increasers the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials

  4. Comparative kinetic study of functionalized carbon nanotubes and magnetic biochar for removal of Cd{sup 2+} ions from wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Ruthiraan, Manimaran; Thines, Raj Kogiladas; Abdullah, Ezzat Chan [Universiti Teknologi Malaysia, Kuala Lumpur (Malaysia); Mubarak, Nabisab Mujawar [UCSI University, Kuala Lumpur (Malaysia); Jayakumar, Natesan Subramanian; Ganesan, Poobalan [University of Malaya, Kuala Lumpur (Malaysia); Sahu, Jaya Narayan [Institut Teknologi Brunei, Gadong (Brunei Darussalam)

    2015-03-15

    We did a comparative study between functionalized multiwall carbon nanotube (FMWCNTs), and magnetic biochar was carried out to determine the most efficient adsorbent to be employed in the Cd{sup 2+} ion removal. We optimized parameters such as agitation speed, contact time, pH and adsorbent dosage using design expert vrsion 6.08. The statistical analysis reveals that optimized condition for highest removal of Cd{sup 2+} are at pH 5.0, with dosage 1.0 g, agitation speed and contact time of 100 rpm and 90 minutes, respectively. For the initial concentration of 10mg/l, the removal efficiency of Cd{sup 2+} using FMWCNTs was 90% and and 82% of magnetic biochar. The maximum Cd{sup 2+} adsorption capacities of both FMWCNTs and magnetic biochar were calculated: 83.33mg/g and 62.5mg/g. The Langmuir and Freundlich constants for FMWCNTs were 0.056 L/mg and 13.613 L/mg, while 0.098 L/mg and 25.204 L/mg for magnetic biochar. The statistical analysis proved that FMWCNTs have better adsorption capacity compared to magnetic biochar and both models obeyed the pseudo-second-order.

  5. A Comparative Study of Growth Kinetics, In Vitro Differentiation Potential and Molecular Characterization of Fetal Adnexa Derived Caprine Mesenchymal Stem Cells

    Science.gov (United States)

    Somal, Anjali; Bhat, Irfan A.; B., Indu; Pandey, Sriti; Panda, Bibhudatta S. K.; Thakur, Nipuna; Sarkar, Mihir; Chandra, Vikash; Saikumar, G.; Sharma, G. Taru

    2016-01-01

    The present study was conducted with an objective of isolation, in vitro expansion, growth kinetics, molecular characterization and in vitro differentiation of fetal adnexa derived caprine mesenchymal stem cells. Mid-gestation gravid caprine uteri (2–3 months) were collected from abattoir to derive mesenchymal stem cells (MSCs) from fetal adnexa {amniotic fluid (cAF), amniotic sac (cAS), Wharton’s jelly (cWJ) and cord blood (cCB)} and expanded in vitro. These cultured MSCs were used at the 3rd passage (P3) to study growth kinetics, localization as well as molecular expression of specific surface antigens, pluripotency markers and mesenchymal tri-lineage differentiation. In comparison to cAF and cAS MSCs, cWJ and cCB MSCs showed significantly (P<0.05) higher clonogenic potency, faster growth rate and low population doubling (PDT) time. All the four types of MSCs were positive for alkaline phosphatase (AP) and differentiated into chondrogenic, osteogenic, and adipogenic lineages. These stem cells expressed MSC surface antigens (CD73, CD90 and CD105) and pluripotency markers (Oct4, Sox2, Nanog, KLF, cMyc, FoxD3) but did not express CD34, a hematopoietic stem cell marker (HSC) as confirmed by RT-PCR, immunocytochemistry and flow cytometric analysis. The relative mRNA expression of MSC surface antigens (CD73, CD90 and CD105) was significantly (P<0.05) higher in cWJ MSCs compared to the other cell lines. The mRNA expression of Oct4 was significantly (P<0.05) higher in cWJ, whereas mRNA expression of KLF and cMyc was significantly (P<0.05) higher in cWJ and cAF than that of cAS and cCB. The comparative assessment revealed that cWJ MSCs outperformed MSCs from other sources of fetal adnexa in terms of growth kinetics, relative mRNA expression of surface antigens, pluripotency markers and tri-lineage differentiation potential, hence, these MSCs could be used as a preferred source for regenerative medicine. PMID:27257959

  6. Comparative study of growth responses and screening of inter-specific OTA production kinetics by A. carbonarius isolated from grapes

    Directory of Open Access Journals (Sweden)

    Iliada eLappa

    2015-05-01

    Full Text Available The aim of this work was to assess OchratoxinA (OTA production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 aw. Samples for OTA determination were removed at 3, 5, 7, 9 and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50-2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density have been measured and correlated with toxin production by means of principal components analysis (PCA, confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time.

  7. Comparative study of growth responses and screening of inter-specific OTA production kinetics by A. carbonarius isolated from grapes

    Science.gov (United States)

    Lappa, Iliada K.; Kizis, Dimosthenis; Natskoulis, Pantelis I.; Panagou, Efstathios Z.

    2015-01-01

    The aim of this work was to assess OchratoxinA (OTA) production of different Aspergillus carbonarius isolates, evaluate their growth profile through different growth measurements, and reveal any underlying correlation between them. Ten different isolates of A. carbonarius isolated from Greek vineyards located in different geographical regions were examined in vitro for their OTA production potential after an incubation period of up to 11 days. All fungal isolates grew on a synthetic grape juice medium (SGM) similar to grape composition at optimum conditions of temperature and water activity (25°C and 0.98 aw). Samples for OTA determination were removed at 3, 5, 7, 9, and 11 days of growth and analyzed by HPLC. Based on OTA measurements the isolates were characterized by diverse OTA production ranging from 50 to 2000 ppb at day 11. The different fungal growth responses (colony diameter, colony area, biomass, biomass dry weight, and colony density) have been measured and correlated with toxin production by means of principal components analysis (PCA), confirming satisfactory correlation and explained over 99% of data variability. Leudeking-Piret model was also used to study OTA production with time, revealing a mixed-growth associated trend and pointing a fail-safe model with slightly better prediction through colony area. This approach contributes to the assessment of correlation between mycotoxin production and different methods of fungal growth determination in relation to time. PMID:26074896

  8. Comparative Kinetic Studies and Performance Evaluation of Biofilm and Biomass Characteristics of Pseudomonas fluorescens in Degrading Synthetic Phenolic Effluent in Inverse Fluidized Bed Biofilm Reactor.

    Science.gov (United States)

    Begum, S Sabarunisha; Radha, K V

    2016-05-01

    The bioremediation potential of Pseudomonas fluorescens was studied in an Inverse Fluidized Bed Biofilm Reactor under batch recirculation conditions using synthetic phenolic effluent of various concentrations (400, 600, 800, 1000 and 1200 mg/l). The performance of the reactor was investigated and the characteristics of biomass and biofilm were determined by evaluating biofilm dry density and thickness, bioparticle density, suspended and attached biomass concentration, chemical oxygen demand and phenol removal efficiency. Biodegradation kinetics had been studied for suspended biomass culture and biofilm systems with respect to its specific growth and substrate consumption rates. Suspended biomass followed substrate inhibition kinetics and the experimental data fitted well with the Haldane model. The degradation kinetic behavior of biofilm revealed that a well adapted biofilm system with effective control of biofilm thickness in an inverse fluidized bed biofilm reactor overcomes substrate inhibition effects by tolerating higher phenol concentration and fitted well to the Monod model.

  9. Spectrophotometric evaluation of surface morphology dependent catalytic activity of biosynthesized silver and gold nanoparticles using UV–vis spectra: A comparative kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Ankamwar, Balaprasad, E-mail: bankamwar@yahoo.com [Bio-inspired Materials Research Laboratory, Department of Chemistry, Savitribai Phule Pune University, Ganeshkhind, Pune 411007 (India); Kamble, Vaishali; Sur, Ujjal Kumar [Bio-inspired Materials Research Laboratory, Department of Chemistry, Savitribai Phule Pune University, Ganeshkhind, Pune 411007 (India); Santra, Chittaranjan [Department of Chemistry, Netaji Nagar Day College, Regent Park, Kolkata 700092 (India)

    2016-03-15

    Graphical abstract: - Highlights: • The biosynthesized silver nanoparticles were stable for 6 months and used as effective SERS active substrate. • They are effective catalyst in the chemical reduction of 4-nitrophenol to 4-aminophenol. • Comparative catalytic efficiency of both silver and gold nanoparticles was studied spectrophotometrically. • Our results demonstrate surface morphology dependent catalytic activity of both nanoparticles. - Abstract: The development of eco-friendly and cost-effective synthetic protocol for the preparation of nanomaterials, especially metal nanoparticles is an emerging area of research in nanotechnology. These metal nanoparticles, especially silver can play a crucial role in various catalytic reactions. The biosynthesized silver nanoparticles described here was very stable up to 6 months and can be further exploited as an effective catalyst in the chemical reduction of 4-nitrophenol to 4-aminophenol. The silver nanoparticles were utilized as an efficient surface-enhanced Raman scattering (SERS) active substrate using Rhodamine 6G as Raman probe molecule. We have also carried out systematic comparative studies on the catalytic efficiency of both silver and gold nanoparticles using UV–vis spectra to monitor the above reaction spectrophotometrically. We find that the reaction follows pseudo-first order kinetics and the catalytic activity can be explained by a simple model based on Langmuir–Hinshelwood mechanism for heterogeneous catalysis. We also find that silver nanoparticles are more efficient as a catalyst compare to gold nanoparticles in the reduction of 4-nitrophenol to 4-aminophenol, which can be explained by the morphology of the nanoparticles as determined by transmission electron microscopy.

  10. Comparative study on the process behavior and reaction kinetics in sonocatalytic degradation of organic dyes by powder and nanotubes TiO2.

    Science.gov (United States)

    Pang, Yean Ling; Abdullah, Ahmad Zuhairi

    2012-05-01

    Sonocatalytic degradation of various organic dyes (Congo Red, Reactive Blue 4, Methyl Orange, Rhodamine B and Methylene Blue) catalyzed by powder and nanotubes TiO(2) was studied. Both catalysts were characterized using transmission electron microscope (TEM), surface analyzer, Raman spectroscope and thermal gravimetric analyzer (TGA). Sonocatalytic activity of powder and nanotubes TiO(2) was elucidated based on the degradation of various organic dyes. The former catalyst was favorable for treatment of anionic dyes, while the latter was more beneficial for cationic dyes. Sonocatalytic activity of TiO(2) nanotubes could be up to four times as compared to TiO(2) powder under an ultrasonic power of 100 W and a frequency of 42 kHz. This was associated with the higher surface area and the electrostatic attraction between dye molecules and TiO(2) nanotubes. Fourier transform-infrared spectrometer (FT-IR) was used to identify changes that occurred on the functional group in Rhodamine B molecules and TiO(2) nanotubes after the reaction. Sonocatalytic degradation of Rhodamine B by TiO(2) nanotubes apparently followed the Langmuir-Hinshelwood adsorption kinetic model with surface reaction rate of 1.75 mg/L min. TiO(2) nanotubes were proven for their high potential to be applied in sonocatalytic degradation of organic dyes.

  11. A comparative study of crystallization kinetics between conventionally melt quenched and mechanochemically synthesized AgI-Ag{sub 2}O-CrO{sub 3} superionic system

    Energy Technology Data Exchange (ETDEWEB)

    Dalvi, Anshuman; Awasthi, A.M.; Bharadwaj, S.; Shahi, K

    2003-10-15

    Non-isothermal crystallization kinetics in conventionally melt quenched versus mechanochemically synthesized amorphous AgI-Ag{sub 2}O-CrO{sub 3} superionic solids is discussed. The quenched as well as ball-milled samples exhibit glass (T{sub g}) and multiple amorphous{yields}crystalline (T{sub c}) transitions. T{sub g} as well as T{sub c} are found to increase monotonically with heating rate. The activation energy for structural relaxation (E{sub s}) obtained using Moynihan equation is found to be higher for ball-milled samples that eventually suggests the relatively rigid and highly viscous structure of milled samples. The activation energy associated with nucleation and growth (E{sub c}) is obtained using Matusita-Sakka equation and its higher value confirms the higher rate of crystallization in ball-milled samples. The values of T{sub c}-T{sub g} and the enthalpy of phase transformation ({delta}H) are also found higher for the ball-milled samples that confirm their comparatively high thermal stability. The electrical conductivity near the crystallization temperatures is studied as a function of time and temperature and these results confirm the presence of amorphous {yields} crystalline transition temperatures in the ball-milled as well as in the melt-quenched samples.

  12. Comparative study of the kinetics and equilibrium of phenol biosorption on immobilized white-rot fungus Phanerochaete chrysosporium from aqueous solution.

    Science.gov (United States)

    Farkas, Viktor; Felinger, Attila; Hegedűsova, Alžbeta; Dékány, Imre; Pernyeszi, Tímea

    2013-03-01

    In this study the kinetics and equilibrium of phenol biosorption were studied from aqueous solution using batch technique at an initial pH of 5.5. The biosorption was studied on Ca-alginate beads, on non-living mycelial pellets of Phanerochaete chrysosporium immobilized on Ca-alginate, and on free fungal biomass. Ph. chrysosporium was grown in a liquid medium containing mineral and vitamin materials with complex composition. The biosorption process followed pseudo second-order kinetics on all bioadsorbents. The bioadsorption-equilibrium on blank Ca-alginate, free and immobilized fungal biomass can be described by Langmuir, anti-Langmuir and Freundlich isotherm models using nonlinear least-squares estimation. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. A comparative study of anaerobic fixed film baffled reactor and up-flow anaerobic fixed film fixed bed reactor for biological removal of diethyl phthalate from wastewater: a performance, kinetic, biogas, and metabolic pathway study.

    Science.gov (United States)

    Yousefzadeh, Samira; Ahmadi, Ehsan; Gholami, Mitra; Ghaffari, Hamid Reza; Azari, Ali; Ansari, Mohsen; Miri, Mohammad; Sharafi, Kiomars; Rezaei, Soheila

    2017-01-01

    Phthalic acid esters, including diethyl phthalate (DEP), which are considered as top-priority and hazardous pollutants, have received significant attention over the last decades. It is vital for industries to select the best treatment technology, especially when the DEP concentration in wastewater is high. Meanwhile, anaerobic biofilm-based reactors are considered as a promising option. Therefore, in the present study, for the biological removal of DEP from synthetic wastewater, two different anaerobic biofilm-based reactors, including anaerobic fixed film baffled reactor (AnFFBR) and up-flow anaerobic fixed film fixed bed reactor (UAnFFFBR), were compared from kinetic and performance standpoints. As in the previous studies, only the kinetic coefficients have been calculated and the relationship between kinetic coefficients and their interpretation has not been evaluated, the other aim of the present study was to fill this research gap. In optimum conditions, 90.31 and 86.91% of COD as well as 91.11 and 88.72% of DEP removal were achieved for the AnFFBR and UAnFFFBR, respectively. According to kinetic coefficients (except biomass yield), the AnFFBR had better performance as it provided a more favorable condition for microbial growth. The Grau model was selected as the best mathematical model for designing and predicting the bioreactors' performance due to its high coefficients of determination (0.97 < R(2)). With regard to the insignificant variations of the calculated Grau kinetic coefficients (KG) when the organic loading rate (with constant HRT) increased, it can be concluded that both of the bioreactors can tolerate high organic loading rate and their performance is not affected by the applied DEP concentrations. Both the bioreactors were capable of treating low-to-high strength DEP wastewater; however, according to the experimental results and obtained kinetic coefficients, the AnFFBR indicated higher performance. Although the AnFFBR can be considered as a

  14. Comparative study of diethyl phthalate degradation by UV/H2O2 and UV/TiO2: kinetics, mechanism, and effects of operational parameters.

    Science.gov (United States)

    Song, Chengjie; Wang, Liping; Ren, Jie; Lv, Bo; Sun, Zhonghao; Yan, Jing; Li, Xinying; Liu, Jingjing

    2016-02-01

    The photodegradation of diethyl phthalate (DEP) by UV/H2O2 and UV/TiO2 is studied. The DEP degradation kinetics and multiple crucial factors effecting the clearance of DEP are investigated, including initial DEP concentration ([DEP]0), initial pH values (pH0), UV light intensity, anions (Cl(-), NO(3-), SO4 (2-), HCO3 (-), and CO3 (2-)), cations (Mg(2+), Ca(2+), Mn(2+), and Fe(3+)), and humic acid (HA). Total organic carbon (TOC) removal is tested by two treatments. And, cytotoxicity evolution of DEP degradation intermediates is detected. The relationship between molar ratio ([H2O2]/[DEP] or [TiO2]/[DEP]) and degradation kinetic constant (K) is also studied. And, the cytotoxicity tests of DEP and its degradation intermediates in UV/H2O2 and UV/TiO2 treatments are researched. The DEP removal efficiency of UV/H2O2 treatment is higher than UV/TiO2 treatment. The DEP degradation fitted a pseudo-first-order kinetic pattern under experimental conditions. The K linearly related with molar ratio in UV/H2O2 treatment while nature exponential relationship is observed in the case of UV/TiO2. However, K fitted corresponding trends better in H2O2 treatment than in TiO2 treatment. The Cl(-) is in favor of the DEP degradation in UV/H2O2 treatment; in contrast, it is disadvantageous to the DEP degradation in UV/TiO2 treatment. Other anions are all disadvantageous to the DEP degradation in two treatments. Fe(3+) promotes the degradation rates significantly. And, all other cations in question inhibit the degradation of DEP. HA hinders DEP degradation in two treatments. The intermediates of DEP degradation in UV/TiO2 treatment are less toxic to biological cell than that in UV/H2O2 treatment.

  15. Simulation and comparative study on the oxidation kinetics of atrazine by UV/H₂O₂, UV/HSO₅⁻ and UV/S₂O₈²⁻.

    Science.gov (United States)

    Luo, Congwei; Ma, Jun; Jiang, Jin; Liu, Yongze; Song, Yang; Yang, Yi; Guan, Yinghong; Wu, Daoji

    2015-09-01

    This study comparatively investigated atrazine (ATZ) degradation by irradiation at the wavelength of 254 nm in the presence of peroxides including hydrogen peroxide (H2O2), peroxymonosulfate (HSO5(-)), and persulfate (S2O8(2-)) at various initial ATZ concentrations and oxidant dosages. The effects of water matrix, such as carbonate/bicarbonate (HCO3(-)/CO3(2-)), chloride ions (Cl(-)), and natural organic matter (NOM), were evaluated on these three advanced oxidation processes. A simple steady-state kinetic model was developed based on the initial rates of ATZ destruction, which could well describe the apparent pseudo-first-order rate constants (k(app), s(-1)) of ATZ degradation in these three processes. The specific roles of reactive species (i.e., HO·, SO4(-·), CO3(-·), and Cl2(-·)) under various experimental conditions were quantitatively evaluated based on their steady-state concentrations obtained from this model. Modeling results showed that the steady-state concentrations of HO· and SO4(-·) decreased with the increase of CO3(2-)/HCO3(-) concentration, and the relative contribution of HO· to ATZ degradation significantly decreased in UV/H2O2 and UV/HSO5(-) systems. On the other hand, the scavenging effect of HCO3(-)/CO3(2-) on the relative contribution of SO4(-·) to ATZ degradation was lower than that on HO·. The presence of Cl(-) (0.5-10 mM) significantly scavenged SO4(-·) but had slightly scavenging effect on HO· at the present experimental pH, resulting in greater decrease of k(app) in the UV/S2O8(2-) than UV/H2O2 and UV/HSO5(-) systems. Higher levels of Cl2(-·) were generated in the UV/S2O8(2-) than those in the UV/H2O2 and UV/HSO5(-) systems at the same Cl(-) concentrations. NOM significantly decreased k(app) due to its effects of competitive UV absorption and radical scavenging with the latter one being dominant. These results improve the understanding of the effects of water constituents for ATZ degradation in the UV-based oxidation

  16. Oxidation of alginate and pectate biopolymers by cerium(IV) in perchloric and sulfuric acid solutions: A comparative kinetic and mechanistic study.

    Science.gov (United States)

    Fawzy, Ahmed

    2016-03-15

    The kinetics of oxidation of alginate (Alg) and pectate (Pec) carbohydrate biopolymers was studied by spectrophotometry in aqueous perchloric and sulfuric acid solutions at fixed ionic strengths and temperature. In both acids, the reactions showed a first order dependence on [Ce(IV)], whereas the orders with respect to biopolymer concentrations are less than unity. In perchloric acid, the reactions exhibited less than unit orders with respect to [H(+)] whereas those proceeded in sulfuric acid showed negative fractional-first order dependences on [H(+)]. The effect of ionic strength and dielectric constant was studied. Probable mechanistic schemes for oxidation reactions were proposed. In both acids, the final oxidation products were characterized as mono-keto derivatives of both biopolymers. The activation parameters with respect to the slow step of the mechanisms were computed and discussed. The rate laws were derived and the reaction constants involved in the different steps of the mechanisms were calculated.

  17. Comparative studies on removal of Erythrosine using ZnS and AgOH nanoparticles loaded on activated carbon as adsorbents: Kinetic and isotherm studies of adsorption.

    Science.gov (United States)

    Ghaedi, M; Rozkhoosh, Z; Asfaram, A; Mirtamizdoust, B; Mahmoudi, Z; Bazrafshan, A A

    2015-03-05

    Erythrosine adsorption (Er) onto ZnS and AgOH nanoparticle-loaded activated carbon (ZnS-NP-AC and AgOH-NP-AC) was studied and results were compared. Subsequent preparation were fully analyzed by different approach such as BET to obtain knowledge about surface area, pore volume, while FT-IR analysis give comprehensive information about functional group the dependency of removal percentage to adsorbent mass, initial Er concentration and contact time were investigated and optimum conditions for pH, adsorbent dosage, Er concentration and contact time was set as be 3.2, 0.016g, 20mg/L and 16min and 3.2, 0.015g, 19mg/L and 2min for ZnS-NP-AC and AgOH-NP-AC, respectively. The equilibrium data correspond to adsorption strongly follow Langmuir model by ZnS-NP-AC and Freundlich model for AgOH-NP-AC. High adsorption capacity for of 55.86-57.80mgg(-1) and 67.11-89.69mgg(-1) for ZnS-NP-AC and AgOH-NP-AC, respectively. The result of present study confirm the applicability of small amount of these adsorbent (95%) in short reasonable time (20min).

  18. Comparative studies on removal of Erythrosine using ZnS and AgOH nanoparticles loaded on activated carbon as adsorbents: Kinetic and isotherm studies of adsorption

    Science.gov (United States)

    Ghaedi, M.; Rozkhoosh, Z.; Asfaram, A.; Mirtamizdoust, B.; Mahmoudi, Z.; Bazrafshan, A. A.

    2015-03-01

    Erythrosine adsorption (Er) onto ZnS and AgOH nanoparticle-loaded activated carbon (ZnS-NP-AC and AgOH-NP-AC) was studied and results were compared. Subsequent preparation were fully analyzed by different approach such as BET to obtain knowledge about surface area, pore volume, while FT-IR analysis give comprehensive information about functional group the dependency of removal percentage to adsorbent mass, initial Er concentration and contact time were investigated and optimum conditions for pH, adsorbent dosage, Er concentration and contact time was set as be 3.2, 0.016 g, 20 mg/L and 16 min and 3.2, 0.015 g, 19 mg/L and 2 min for ZnS-NP-AC and AgOH-NP-AC, respectively. The equilibrium data correspond to adsorption strongly follow Langmuir model by ZnS-NP-AC and Freundlich model for AgOH-NP-AC. High adsorption capacity for of 55.86-57.80 mg g-1 and 67.11-89.69 mg g-1 for ZnS-NP-AC and AgOH-NP-AC, respectively. The result of present study confirm the applicability of small amount of these adsorbent (95%) in short reasonable time (20 min).

  19. Comparative study of RBE and cell survival fractions for $^{1}$H, $^{4}$He, $^{12}$C and $^{16}$O beams using Geant4 and Microdosimetric Kinetic model

    CERN Document Server

    Burigo, Lucas; Mishustin, Igor; Bleicher, Marcus

    2014-01-01

    Beams of $^{4}$He and $^{16}$O nuclei are considered for ion-beam cancer therapy as alternative options to protons and $^{12}$C nuclei. Spread-out Bragg peak (SOBP) distributions of physical dose and relative biological effectiveness for 10% survival are calculated by means of our Geant4-based Monte Carlo model for Heavy Ion Therapy (MCHIT) and the modified microdosimetric kinetic model. The depth distributions of cell survival fractions are calculated for $^{1}$H, $^{4}$He, $^{12}$C and $^{16}$O for tissues with normal (HSG cells), low and high radiosensitivity. In each case the cell survival fractions were compared separately for the target volume, behind and in front of it. In the case of normal radiosensitivity $^{4}$He and $^{12}$C better spare tissues in the entrance channel compared to protons and $^{16}$O. The cell survival fractions calculated, respectively, for the entrance channel and target volume are similar for $^{4}$He and $^{12}$C. When it is important to spare healthy tissues located after th...

  20. Comparative bioaccumulation kinetics of trace elements in Mediterranean marine sponges.

    Science.gov (United States)

    Genta-Jouve, Grégory; Cachet, Nadja; Oberhänsli, François; Noyer, Charlotte; Teyssié, Jean-Louis; Thomas, Olivier P; Lacoue-Labarthe, Thomas

    2012-09-01

    While marine organisms such as bivalves, seagrasses and macroalgae are commonly used as biomonitors for the environment pollution assessment, widely distributed sponges received little attention as potential helpful species for monitoring programmes. In this study, the trace element and radionuclide bioaccumulation and retention capacities of some marine sponges were estimated in a species-comparative study using radiotracers technique. Six Mediterranean species were exposed to background dissolved concentrations of (110m)Ag, (241)Am, (109)Cd, (60)Co, (134)Cs, (54)Mn, (75)Se and (65)Zn allowing the assessment of the uptake and depuration kinetics for selected elements. Globally, massive demosponges Agelas oroides, Chondrosia reniformis and Ircinia variabilis displayed higher concentration factor (CF) than the erectile ones (Acanthella acuta, Cymbaxinella damicornis, Cymbaxinella verrucosa) at the end of exposure, suggesting that the morphology is a key factor in the metal bioaccumulation efficiency. Considering this observation, two exceptions were noted: (1) A. acuta reached the highest CF for (110m)Ag and strongly retained the accumulated metal without significant Ag loss when placed in depuration conditions and (2) C. reniformis did not accumulate Se as much as A. oroides and I. variabilis. These results suggest that peculiar metal uptake properties in sponges could be driven by specific metabolites or contrasting biosilification processes between species, respectively. This study demonstrated that sponges could be considered as valuable candidate for biomonitoring metal contamination but also that there is a need to experimentally highlight metal-dependant characteristic among species.

  1. Comparative kinetic analysis of two fungal β-glucosidases

    Directory of Open Access Journals (Sweden)

    Casanave Dominique

    2010-02-01

    Full Text Available Abstract Background The enzymatic hydrolysis of cellulose is still considered as one of the main limiting steps of the biological production of biofuels from lignocellulosic biomass. It is a complex multistep process, and various kinetic models have been proposed. The cellulase enzymatic cocktail secreted by Trichoderma reesei has been intensively investigated. β-glucosidases are one of a number of cellulolytic enzymes, and catalyze the last step releasing glucose from the inhibitory cellobiose. β-glucosidase (BGL1 is very poorly secreted by Trichoderma reesei strains, and complete hydrolysis of cellulose often requires supplementation with a commercial β-glucosidase preparation such as that from Aspergillus niger (Novozymes SP188. Surprisingly, kinetic modeling of β-glucosidases lacks reliable data, and the possible differences between native T. reesei and supplemented β-glucosidases are not taken into consideration, possibly because of the difficulty of purifying BGL1. Results A comparative kinetic analysis of β-glucosidase from Aspergillus niger and BGL1 from Trichoderma reesei, purified using a new and efficient fast protein liquid chromatography protocol, was performed. This purification is characterized by two major steps, including the adsorption of the major cellulases onto crystalline cellulose, and a final purification factor of 53. Quantitative analysis of the resulting β-glucosidase fraction from T. reesei showed it to be 95% pure. Kinetic parameters were determined using cellobiose and a chromogenic artificial substrate. A new method allowing easy and rapid determination of the kinetic parameters was also developed. β-Glucosidase SP188 (Km = 0.57 mM; Kp = 2.70 mM has a lower specific activity than BGL1 (Km = 0.38 mM; Kp = 3.25 mM and is also more sensitive to glucose inhibition. A Michaelis-Menten model integrating competitive inhibition by the product (glucose has been validated and is able to predict the

  2. Methods for the analysis of cellular kinetics in PHA-stimulated blood lymphocytes using BrdU incorporation. A comparative study.

    Science.gov (United States)

    Palma, V; Tudón, H; Buentello, L; Nava, S; Ostrosky, P; Salamanca, F

    1993-04-01

    The cellular cycle (cc) span was measured by using differential sister-chromatid staining (DSCS) and applying the following methods: cellular cycle time (cct) according to the graphic method of Dutrillaux and Fosse (G-cct); the analytical equation (A-cct) proposed in the present paper, and the average generation time (AGT) suggested by Ivett and Tice. The mean values obtained by the three methods were 12.5, 12.7, and 19.5 h, respectively. A-cct is the more precise method, since the equation of the analytical procedure allows the utilization of numerical data, and when the graphical method is used, the values plotted in a graph may vary according to the employed scale. Cct is the choice over AGT because the first evaluates actively dividing cells and only considers those at M2 or M3. It will be useful to study cell proliferation kinetics in genetic pathological conditions and to investigate with accuracy the effect of cytostatic and cytotoxic drugs.

  3. KINETICS STUDY ON NITRATION OF METHYL RICINOLEATE

    OpenAIRE

    Abdullah, Abdullah; Triyono, Triyono; Trisunaryanti, Wega; Haryadi, Winarto

    2012-01-01

    Kinetics parameter values of methyl ricinoleate nitration (rate constant, reaction order and the rate of reaction) have been determined. Nitration was carried out with both concentrations of HNO3 and acetic anhydride in excess to the concentration of methyl ricinoleate. Thus, the kinetics parameter value was only affected by the concentration of methyl ricinoleate. Based on kinetic study conducted, it could be concluded that the nitration follows pseudo first-order, and the reaction rate for ...

  4. Comparative kinetics of the snowball respect to other dynamical objects

    CERN Document Server

    Díaz, R A; Marin, F; Martínez, R; Diaz, Rodolfo A.; Gonzalez, Diego L.; Marin, Francisco

    2003-01-01

    We examine the kinetics of a snowball that is gaining mass while is rolling downhill. This dynamical system combines rotational effects with effects involving the variation of mass. In order to understand the consequences of both effects we compare its behavior with the one of some objects in which such effects are absent. Environmental conditions are also included. We conclude that the comparative velocity of the snowball is very sensitive to the hill profile and the retardation factors. We emphasize that the increase of mass (inertia), could surprisingly diminish the retardation effect due to the drag force. Additionally, when an exponential trajectory is assumed, the maximum velocity of the snowball can be reached at an intermediate step of the trip.

  5. Liquefaction chemistry and kinetics: Hydrogen utilization studies

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberger, K.S.; Warzinski, R.P.; Cugini, A.V. [Pittsburgh Energy Technology Center, PA (United States)] [and others

    1995-12-31

    The objectives of this project are to investigate the chemistry and kinetics that occur in the initial stages of coal liquefaction and to determine the effects of hydrogen pressure, catalyst activity, and solvent type on the quantity and quality of the products produced. The project comprises three tasks: (1) preconversion chemistry and kinetics, (2) hydrogen utilization studies, and (3) assessment of kinetic models for liquefaction. The hydrogen utilization studies work will be the main topic of this report. However, the other tasks are briefly described.

  6. Equilibrium and kinetics study on removal of arsenate ions from aqueous solution by CTAB/TiO2 and starch/CTAB/TiO2 nanoparticles: a comparative study.

    Science.gov (United States)

    Gogoi, Pankaj; Dutta, Debasish; Maji, Tarun Kr

    2017-02-01

    We present a comparative study on the efficacy of TiO2 nanoparticles for arsenate ion removal after modification with CTAB (N-cetyl-N,N,N-trimethyl ammonium bromide) followed by coating with starch biopolymer. The prepared nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), thermogravimetry, scanning electron microscopy (SEM) and electron dispersive X-ray analysis (EDX). The removal efficiency was studied as a function of contact time, material dose and initial As(V) concentration. CTAB-modified TiO2 showed the highest arsenate ion removal rate (∼99% from 400 μg/L). Starch-coated CTAB-modified TiO2 was found to be best for regeneration. For a targeted solution of 400 μg/L, a material dose of 2 g/L was found to be sufficient to reduce the As(V) concentration below 10 μg/L. Equilibrium was established within 90 minutes of treatment. The sorption pattern followed a Langmuir monolayer pattern, and the maximum sorption capacity was found to be 1.024 mg/g and 1.423 mg/g after starch coating and after CTAB modification, respectively. The sorption mechanisms were governed by pseudo second order kinetics.

  7. Drug screening in urine by cloned enzyme donor immunoassay (CEDIA) and kinetic interaction of microparticles in solution (KIMS): a comparative study.

    Science.gov (United States)

    Schwettmann, Lutz; Külpmann, Wolf-Rüdiger; Vidal, Christian

    2006-01-01

    Two commercially available drug-screening assays were evaluated: the Roche kinetic interaction of microparticles in solution (KIMS) assay and the Microgenics cloned enzyme donor immunoassay (CEDIA). Urine samples from known drug-abuse patients were analyzed for amphetamines, barbiturates, benzodiazepines, benzoylecgonine, cannabinoids, LSD, methadone and opiates. Samples with discordant findings for the two assays were analyzed by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/electron capture detection (GC/ECD). Amphetamines showed 96.0% concordant results, with two false positive findings by CEDIA, three by KIMS and a further two false negatives by KIMS. Barbiturates showed 99.4% concordant results, with one false negative by KIMS. Benzodiazepines showed 97.4% concordant results, with two false negatives by KIMS (cutoff 100 microg/L, CEDIA cutoff 300 microg/L). Benzoylecgonine showed 17.8% concordant positive and 82.2% concordant negative results and no false finding by either assay. Cannabinoids showed 99.3% concordant results, with one sample negative by KIMS at a cutoff of 50 microg/L and positive by CEDIA (cutoff 25 microg/L). For LSD, 6.7% of findings were not in agreement. Methadone showed 97.5% concordant results, with two false positives by CEDIA, and one false positive and one false negative by KIMS. Opiates showed 96.9% concordant results, with no false KIMS results, but four false positives by CEDIA. The results indicate that the agreement of the CEDIA and KIMS results for the eight drugs is rather good (93.3-100%).

  8. Comparative study of kinetics of adsorption of methylene blue from aqueous solutions using cinnamon plant (Cinnamonum zeylanicum leaf powder and pineapple (Ananas comosus peel powder

    Directory of Open Access Journals (Sweden)

    Satish Dnyandeo Patil

    2012-07-01

    Full Text Available Batch adsorption of methylene blue (MB onto Cinnamon plant (Cinnamonum Zeylanicum leaf powder (CPLP and Pineapple (Ananas Comosus peel powder (PPP was investigated. Different parameters such as initial sorbate concentration, adsorbent dosage, pH, contact time, agitation speed, temperature and particle size. All isotherm models were found to be best fitting with high values of regression coefficient i.e. for Langmuir (R2 = 0.989 to 0.994 for CPLP and 0.993 to 0.995 for PPP, for Freundlich (R2 = 0.996 to 0.998 for CPLP and 0.995 for PPP and for Temkin (R2 = 0.983 to 0.995 for CPLP and 0.984 to 0.989 for PPP. The monolayer (maximum adsorption capacities (qm were found to be 250 and 333.333 mg/g for CPLP and PPP respectively. Lagergen pseudo -second order model best fits the kinetics of adsorption (R2 = 0.999 for CPLP and 1 for PPP. The amount of dye adsorbed at equilibrium qe(the obtained from Lagergen pseudo -second order model were found to be nearly same with the experimental data. Intra particle diffusion plot showed boundary layer effect and larger intercepts indicates greater contribution of surface sorption in rate determining step. Adsorption was found to be directly proportional to pH and temperature but inversely proportional to particle size. Thermodynamic analysis (∆G, ∆H and ∆S values showed adsorption was favourable, spontaneous, endothermic physisorption and increased disorder and randomness at the solid- solution interface of MB with the adsorbents. The forward rate constant was much higher than reverse rate constant suggesting dominance of rate of adsorption. PPP was found to be better adsorbent than CPLP.

  9. Comparative study of cellular kinetics of reporter probe [{sup 131}I]FIAU in neonatal cardiac myocytes after transfer of HSV1-tk reporter gene with two vectors

    Energy Technology Data Exchange (ETDEWEB)

    Lan Xiaoli [Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022 (China)], E-mail: lxl730724@hotmail.com; Yin Xiaohua; Wang Ruihua; Liu Ying [Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022 (China); Zhang Yongxue [Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China) and Hubei Province Key Laboratory of Molecular Imaging, Wuhan 430022 (China)], E-mail: zhyx1229@163.com

    2009-02-15

    Aim: Reporter gene imaging is a promising approach for noninvasive monitoring of cardiac gene therapy. In this study, HSV1-tk (herpes simplex virus type 1 thymidine kinase) and FIAU (2'-fluoro-2'-deoxy-1-{beta}-D-arabinofuranosyl-5-iodouracil) were used as the reporter gene and probe, respectively. Cellular uptakes of radiolabeled FIAU of neonatal rat cardiac myocytes transferred with HSV1-tk were compared between two vectors, adenovirus and liposome. The aims of this study were to choose the better vector and to provide a theoretical basis for good nuclide images. Methods: Neonatal cardiac myocytes were obtained from rat heart by single collagenase digestion. HSV1-tk inserted into adenovirus vector (recombinant adenovirus type 5, Ad5-tk) and plasmid (pDC316-tk) coated with Lipofectamine 2000 (pDC316-tk/lipoplex) were developed; thus, HSV1-tk could be transferred into neonatal cardiac myocytes. FAU (2'-fluoro-2'-deoxy-1-{beta}-D-arabinofuranosyluracil) was labeled with {sup 131}I, and the product was assessed after purification with reversed-phase Sep-Pak C-18 column. The uptake rates of [{sup 131}I]FIAU in the transferred cardiac myocytes at different times (0.5, 1, 2, 3, 4 and 5 h) were detected. Furthermore, mRNA expression and protein expression of HSV1-tk were detected by semiquantitative reverse-transcriptase polymerase chain reaction and immunocytochemistry. Results: FAU could be labeled with {sup 131}I, and the labeling efficiency and radiochemical purity rates were 53.82{+-}2.05% and 94.85{+-}1.76%, respectively. Time-dependent increase of the accumulation of [{sup 131}I]FIAU was observed in both the Ad5-tk group and the pDC316/lipoplex group, and the highest uptake rate occurred at 5 h, with peak values of 12.55{+-}0.37% and 2.09{+-}0.34%, respectively. Greater uptakes of [{sup 131}I]FIAU in Ad5-tk-infected cells compared with pDC316/lipoplex-transfected ones occurred at all the time points (t=12.978-38.253, P<.01). The exogenous gene

  10. Kinetic studies of elementary chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Durant, J.L. Jr. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    This program concerning kinetic studies of elementary chemical reactions is presently focussed on understanding reactions of NH{sub x} species. To reach this goal, the author is pursuing experimental studies of reaction rate coefficients and product branching fractions as well as using electronic structure calculations to calculate transition state properties and reaction rate calculations to relate these properties to predicted kinetic behavior. The synergy existing between the experimental and theoretical studies allow one to gain a deeper insight into more complex elementary reactions.

  11. Comparative kinetic analysis of silent and ultrasound-assisted catalytic wet peroxide oxidation of phenol.

    Science.gov (United States)

    Rokhina, Ekaterina V; Repo, Eveliina; Virkutyte, Jurate

    2010-03-01

    The kinetic study of silent and ultrasound-assisted catalytic wet peroxide oxidation of phenol in water was performed to qualitatively assess the effect of ultrasound on the process kinetics. Various kinetic parameters such as the apparent kinetic rate constants, the surface utilization coefficient and activation energy of phenol oxidation over RuI(3) catalyst were investigated. Comparative analysis revealed that the use of ultrasound irradiation reduced the energy barrier of the reaction but had no impact on the reaction pathway. The activation energy for the oxidation of phenol over RuI(3) catalyst in the presence of ultrasound was found to be 13kJmol(-1), which was four times smaller in comparison to the silent oxidation process (57kJmol(-1)). Finally, 'figures-of-merit' was utilized to assess different experimental strategies such as sonolysis alone, H(2)O(2)-enhanced sonolysis and sono-catalytic oxidation of phenol in order to estimate the electric energy consumption based on the kinetic rate constants of the oxidation process.

  12. Comparative study of photocatalytic activities of Zn5(OH)8Cl2·H2O and ZnO nanostructures in ciprofloxacin degradation: Response surface methodology and kinetic studies.

    Science.gov (United States)

    Nekouei, Farzin; Nekouei, Shahram

    2017-12-01

    Zinc hydroxide chloride monohydrate (Zn5(OH)8Cl2·H2O) and zinc oxide (ZnO) nanostructures were synthesized by simple precipitation and pyrolysis methods, respectively and characterized by means of various instrumental methods. Their photocatalytic efficiencies as two potential photocatalysts for photodegradation of a clinical wastewater, ciprofloxacin (CIP), were probed and compared. The results indicated that in comparison with Zn5(OH)8Cl2·H2O nanoplates, the photodegradation was 1.4 times faster when using ZnO nanoparticles as well as higher removal percentage. The optimum pH obtained was 8 that it is typically found for hospital wastewater. Analysis of variance (ANOVA) exhibited high R(2) values, high F-values, very low P-values, and non-significant lack of fit values demonstrating good correlation between experimental and predicted values of the response for both catalysts. Kinetic studies identified first order model as a suitable model for description of photodegradation processes for both nanosized Zn5(OH)8Cl2·H2O and ZnO. The chemical oxygen demand (COD) removal of 43.30 and 56.30% were obtained after 24h for Zn5(OH)8Cl2·H2O nanoplates and ZnO nanoparticles, respectively. Ultra-performance liquid chromatography method coupled with tandem mass spectrometry (UPLC-MS/MS) for the determination of CIP degradation products has been used. Taken together, ZnO nanoparticles were more efficient in CIP removal due to some properties as in higher surface area and lower band gap. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Comparative Analysis of Thermal Behavior, Isothermal Crystallization Kinetics and Polymorphism of Palm Oil Fractions

    OpenAIRE

    Zhang, Xia; Lin LI; Xie, He; Liang, Zhili; Su, Jianyu; Liu, Guoqin; LI, Bing

    2013-01-01

    Thermal behavior of palm stearin (PS) and palm olein (PO) was explored by monitoring peak temperature transitions by differential scanning calorimetry (DSC). The fatty acid composition (FAC), isothermal crystallization kinetics studied by pulsed Nuclear Magnetic Resonance (pNMR) and isothermal microstructure were also compared. The results indicated that the fatty acid composition had an important influence on the crystallization process. PS and PO both exhibited more multiple endotherms than...

  14. Comparative evaluation of adsorption kinetics of diclofenac and isoproturon by activated carbon.

    Science.gov (United States)

    Torrellas, Silvia A; Rodriguez, Araceli R; Escudero, Gabriel O; Martín, José María G; Rodriguez, Juan G

    2015-01-01

    Adsorption mechanism of diclofenac and isoproturon onto activated carbon has been proposed using Langmuir and Freundlich isotherms. Adsorption capacity and optimum adsorption isotherms were predicted by nonlinear regression method. Different kinetic equations, pseudo-first-order, pseudo-second-order, intraparticle diffusion model and Bangham kinetic model, were applied to study the adsorption kinetics of emerging contaminants on activated carbon in two aqueous matrices.

  15. Comparative Packaging Study

    Science.gov (United States)

    Perchonok, Michele; Antonini, David

    2008-01-01

    This viewgraph presentation describes a comparative packaging study for use on long duration space missions. The topics include: 1) Purpose; 2) Deliverables; 3) Food Sample Selection; 4) Experimental Design Matrix; 5) Permeation Rate Comparison; and 6) Packaging Material Information.

  16. Degradation kinetics of cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside during hot air and vacuum drying in mulberry (Morus alba L.) fruit: A comparative study based on solid food system.

    Science.gov (United States)

    Zhou, Mo; Chen, Qinqin; Bi, Jinfeng; Wang, Yixiu; Wu, Xinye

    2017-08-15

    The aim of this study is to ascertain the degradation kinetic of anthocyanin in dehydration process of solid food system. Mulberry fruit was treated by hot air and vacuum drying at 60 and 75°C. The contents of cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside were determined by using high performance liquid chromatography. Kinetic and thermodynamic parameters were calculated for analysing the degradation characteristics. Model fitting results showed monomeric anthocyanin degradations were followed the second-order kinetic. Vacuum drying presented high kinetic rate constants and low t1/2 values. Thermodynamic parameters including the activation energy, enthalpy change and entropy change appeared significant differences between hot air and vacuum drying. Both heating techniques showed similar effects on polyphenol oxidase activities. These results indicate the anthocyanin degradation kinetic in solid food system is different from that in liquid and the oxygen can be regarded as a catalyst to accelerate the degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Transport Reversal during Heteroexchange: A Kinetic Study

    Directory of Open Access Journals (Sweden)

    V. Makarov

    2013-01-01

    Full Text Available It is known that secondary transporters, which utilize transmembrane ionic gradients to drive their substrates up a concentration gradient, can reverse the uptake and instead release their substrates. Unfortunately, the Michaelis-Menten kinetic scheme, which is popular in transporter studies, does not include transporter reversal, and it completely neglects the possibility of equilibrium between the substrate concentrations on both sides of the membrane. We have developed a complex two-substrate kinetic model that includes transport reversal. This model allows us to construct analytical formulas allowing the calculation of a “heteroexchange” and “transacceleration” using standard Michaelis coefficients for respective substrates. This approach can help to understand how glial and other cells accumulate substrates without synthesis and are able to release such substrates and gliotransmitters.

  18. Kinetic study and mechanism of Niclosamide degradation

    Science.gov (United States)

    Zaazaa, Hala E.; Abdelrahman, Maha M.; Ali, Nouruddin W.; Magdy, Maimana A.; Abdelkawy, M.

    2014-11-01

    A spectrophotometric kinetic study of Niclosamide alkaline degradation as a function of drug concentration, alkaline concentration and temperature has been established utilizing double divisor-ratio spectra spectrophotometric method. The developed method allowed determination of Niclosamide in presence of its alkaline degradation products; namely; 2-chloro-4-nitro aniline (DEG I) and 5-chloro salicylic acid (DEG II) with characterization of its degradation mechanism. It was found that degradation kinetic of Niclosamide followed pseudo-first order under the established experimental conditions with a degradation rate constant (k) of 0.0829 mol/h and half life (t1/2) of 8.35 h. The overall degradation rate constant as a function of the temperature under the given conditions obeyed Arrhenius equation where the activation energy was calculated to be 3.41 kcal/mol.

  19. Thermo-Kinetic Investigation of Comparative Ligand Effect on Cysteine Iron Redox Reaction

    Directory of Open Access Journals (Sweden)

    Masood Ahmad Rizvi

    2015-03-01

    Full Text Available Transition metal ions in their free state bring unwanted biological oxidations generating oxidative stress. The ligand modulated redox potential can be indispensable in prevention of such oxidative stress by blocking the redundant bio-redox reactions. In this study we investigated the comparative ligand effect on the thermo-kinetic aspects of biologically important cysteine iron (III redox reaction using spectrophotometric and potentiometric methods. The results were corroborated with the complexation effect on redox potential of iron(III-iron(II redox couple. The selected ligands were found to increase the rate of cysteine iron (III redox reaction in proportion to their stability of iron (II complex (EDTA < terpy < bipy < phen. A kinetic profile and the catalytic role of copper (II ions by means of redox shuttle mechanism for the cysteine iron (III redox reaction in presence of 1,10-phenanthroline (phen ligand is also reported.

  20. Studies of combustion kinetics and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Gutman, D. [Catholic Univ. of America, Washington, DC (United States)

    1993-12-01

    The objective of the current research is to gain new quantitative knowledge of the kinetics and mechanisms of polyatomic free radicals which are important in hydrocarbon combustion processes. The special facility designed and built for these (which includes a heatable tubular reactor coupled to a photoionization mass spectrometer) is continually being improved. Where possible, these experimental studies are coupled with theoretical ones, sometimes conducted in collaboration with others, to obtain an improved understanding of the factors determining reactivity. The decomposition of acetyl radicals, isopropyl radicals, and n-propyl radicals have been studied as well as the oxidation of methylpropargyl radicals.

  1. Kinetic and Thermodynamic Studies of Charge-Transfer Complex ...

    African Journals Online (AJOL)

    Kinetic and Thermodynamic Studies of Charge-Transfer Complex Formation ... The activation parameters, i.e. activation energy, enthalpy, and entropy of ... KEYWORDS Charge-transfer complex, imipramine, DDQ, ionization potential, kinetic, ...

  2. ENZYMATIC KINETIC STUDY HYDROLASE FROM CITRUS

    Directory of Open Access Journals (Sweden)

    Israel Hernández

    2015-09-01

    Full Text Available In this paper the degrading activity of enzymes derived from orange peels (Citrus x sinensis, grapefruit (Citrus paradise and pineapple (Ananas comosus on the organic matter in wastewater is evaluated. This activity is measured indirectly by quantifying the biochemical oxygen demand (COD before and after degradation process based on a period of time using the HACH DR / 2010, and then the kinetic study was performed by the differential method and integral with the experimental data, obtaining a reaction order of 1 to pectinase (orange, and order 2 for bromelain (pineapple.

  3. In vitro comparative kinetic analysis of the chloroplast Toc GTPases.

    Science.gov (United States)

    Reddick, L Evan; Vaughn, Michael D; Wright, Sarah J; Campbell, Ian M; Bruce, Barry D

    2007-04-13

    A unique aspect of protein transport into plastids is the coordinate involvement of two GTPases in the translocon of the outer chloroplast membrane (Toc). There are two subfamilies in Arabidopsis, the small GTPases (Toc33 and Toc34) and the large acidic GTPases (Toc90, Toc120, Toc132, and Toc159). In chloroplasts, Toc34 and Toc159 are implicated in precursor binding, yet mechanistic details are poorly understood. How the GTPase cycle is modulated by precursor binding is complex and in need of careful dissection. To this end, we have developed novel in vitro assays to quantitate nucleotide binding and hydrolysis of the Toc GTPases. Here we present the first systematic kinetic characterization of four Toc GTPases (cytosolic domains of atToc33, atToc34, psToc34, and the GTPase domain of atToc159) to permit their direct comparison. We report the KM, Vmax, and Ea values for GTP hydrolysis and the Kd value for nucleotide binding for each protein. We demonstrate that GTP hydrolysis by psToc34 is stimulated by chloroplast transit peptides; however, this activity is not stimulated by homodimerization and is abolished by the R133A mutation. Furthermore, we show peptide stimulation of hydrolytic rates are not because of accelerated nucleotide exchange, indicating that transit peptides function as GTPase-activating proteins and not guanine nucleotide exchange factors in modulating the activity of psToc34. Finally, by using the psToc34 structure, we have developed molecular models for atToc33, atToc34, and atToc159G. By combining these models with the measured enzymatic properties of the Toc GTPases, we provide new insights of how the chloroplast protein import cycle may be regulated.

  4. Adsorption studies of molasse's wastewaters on activated carbon: modelling with a new fractal kinetic equation and evaluation of kinetic models.

    Science.gov (United States)

    Figaro, S; Avril, J P; Brouers, F; Ouensanga, A; Gaspard, S

    2009-01-30

    Adsorption kinetic of molasses wastewaters after anaerobic digestion (MSWD) and melanoidin respectively on activated carbon was studied at different pH. The kinetic parameters could be determined using classical kinetic equations and a recently published fractal kinetic equation. A linear form of this equation can also be used to fit adsorption data. Even with lower correlation coefficients the fractal kinetic equation gives lower normalized standard deviation values than the pseudo-second order model generally used to fit adsorption kinetic data, indicating that the fractal kinetic model is much more accurate for describing the kinetic adsorption data than the pseudo-second order kinetic model.

  5. Operations dashboard: comparative study

    Science.gov (United States)

    Ramly, Noor Nashriq; Ismail, Ahmad Zuhairi; Aziz, Mohd Haris; Ahmad, Nurul Haszeli

    2011-10-01

    In this present days and age, there are increasing needs for companies to monitor application and infrastructure health. Apart from having proactive measures to secure their application and infrastructure, many see monitoring dashboards as crucial investment in disaster preparedness. As companies struggle to find the best solution to cater for their needs and interest for monitoring their application and infrastructure's health, this paper summarizes the studies made on several known off-the-shelf operations dashboard and in-house developed dashboard. A few criteria of good dashboard are collected from previous studies carried out by several researchers and rank them according to importance and business needs. The finalized criteria that will be discussed in later sections are data visualization, performance indicator, dashboard personalization, audit capability and alert/ notification. Comparative studies between several popular dashboards were then carried out to determine whether they met these criteria that we derived from the first exercise. The findings hopefully can be used to educate and provide an overview of selecting the best IT application and infrastructure operations dashboard that suit business needs, thus become the main contribution of this paper.

  6. Comparative assessment of in vitro release kinetics of calcitonin polypeptide from biodegradable microspheres.

    Science.gov (United States)

    Prabhu, Sunil; Sullivan, Jennifer L; Betageri, Guru V

    2002-01-01

    The objective of our study was to compare the in vitro release kinetics of a sustained-release injectable microsphere formulation of the polypeptide drug, calcitonin (CT), to optimize the characteristics of drug release from poly-(lactide-co-glycolide) (PLGA) copolymer biodegradable microspheres. A modified solvent evaporation and double emulsion technique was used to prepare the microspheres. Release kinetic studies were carried out in silanized tubes and dialysis bags, whereby microspheres were suspended and incubated in phosphate buffered saline, sampled at fixed intervals, and analyzed for drug content using a modified Lowry protein assay procedure. An initial burst was observed whereby about 50% of the total dose of the drug was released from the microspheres within 24 hr and 75% within 3 days. This was followed by a period of slow release over a period of 3 weeks in which another 10-15% of drug was released. Drug release from the dialysis bags was more gradual, and 50% CT was released only after 4 days and 75% after 12 days of release. Scanning electron micrographs revealed spherical particles with channel-like structures and a porous surface after being suspended in an aqueous solution for 5 days. Differential scanning calorimetric studies revealed that CT was present as a mix of amorphous and crystalline forms within the microspheres. Overall, these studies demonstrated that sustained release of CT from PLGA microspheres over a 3-week period is feasible and that release of drug from dialysis bags was more predictable than from tubes.

  7. Catalyst Kinetics Analytical Method Study of Ruthenium

    Institute of Scientific and Technical Information of China (English)

    Kou ming-ze; Zhan hui-ying; Kou zong-yan

    2004-01-01

    Color reactions are used to determine ruthenium utilizing spectrophotometer, but the process need high temperature, long time pyrogenation and miscellaneous extraction and it contaminates the enviroment. As the sensitive degree and simple apparatus of catalyst kinetics analytical method, it was extensively attentcd. The fundmental principle means to determinn a certain chemistry reaction rate accelerated by homogeneous catalyst and determine substantial content using the function of the numerical value of of its and the catalyst concentration. Color acid double azo-reagents (chloro-phosphor group, arsenic group and carboxylic acid group) are sensitive color reagent determining uranium and thorium of lanthanon, but the report is few that it is used to determine ruthenium. Since 1990s, the author studied that the ruthenium was possessed evident catalysis to the fade reaction of oxidant (KIO4, KBrO3) oxidating color acid double azo-reagent in acitidy medium and provided the catalyst kinetics analytical method to determine trace ruthenium.sensitive degree was increased 1 ~2 amount than color reaction. The reaction as:The original concentration of color acid double azo-reagents is A. The instantaneous absorbency after t reaction time is At. In homogeneous catalyst reaction: log(A0/At) = KCRu3+t. Reaction time t is invarible, so log(A0/At) = K' CRu3+t.Color acid double azo-reagents, such as: chlor-azochlorphosphor(CPA-TC),bromic-azochlorphosphor (CPA-TB), DBS-azochlorphosphor(DBS-CPA), DBC-azochlorphosphor (DBC-CPA), DBOK-azochlorpho sphor (DBOK-CPA), p-iodineazochlorphosphor(CPA-PI),p-acetylazochlorphosphor (CPA-PA), azochlorpho sphorⅢ(CPAⅢ), chlor-azoarsenic (TC-AsA),bromic-azoarsenic (TB-AsA), DBS-azoarsenic(DCS-AsA), DCS-azoarsenic(DCS-AsA),azoarsenicⅢ(AsAⅢ), bromicnityrlazoarsenic (DBN-AsA), P-acetylcarboxy lazo-p,P-acetylcarboxylazo, were utilized in catalyst kinetics system. The author obtains the satisfactory results that color acid double azo-rea gents

  8. Comparative waste forms study

    Energy Technology Data Exchange (ETDEWEB)

    Wald, J.W.; Lokken, R.O.; Shade, J.W.; Rusin, J.M.

    1980-12-01

    A number of alternative process and waste form options exist for the immobilization of nuclear wastes. Although data exists on the characterization of these alternative waste forms, a straightforward comparison of product properties is difficult, due to the lack of standardized testing procedures. The characterization study described in this report involved the application of the same volatility, mechanical strength and leach tests to ten alternative waste forms, to assess product durability. Bulk property, phase analysis and microstructural examination of the simulated products, whose waste loading varied from 5% to 100% was also conducted. The specific waste forms investigated were as follows: Cold Pressed and Sintered PW-9 Calcine; Hot Pressed PW-9 Calcine; Hot Isostatic Pressed PW-9 Calcine; Cold Pressed and Sintered SPC-5B Supercalcine; Hot Isostatic pressed SPC-5B Supercalcine; Sintered PW-9 and 50% Glass Frit; Glass 76-68; Celsian Glass Ceramic; Type II Portland Cement and 10% PW-9 Calcine; and Type II Portland Cement and 10% SPC-5B Supercalcine. Bulk property data were used to calculate and compare the relative quantities of waste form volume produced at a spent fuel processing rate of 5 metric ton uranium/day. This quantity ranged from 3173 L/day (5280 Kg/day) for 10% SPC-5B supercalcine in cement to 83 L/day (294 Kg/day) for 100% calcine. Mechanical strength, volatility, and leach resistance tests provide data related to waste form durability. Glass, glass-ceramic and supercalcine ranked high in waste form durability where as the 100% PW-9 calcine ranked low. All other materials ranked between these two groupings.

  9. Kinetics study on conventional and microwave pyrolysis of moso bamboo.

    Science.gov (United States)

    Dong, Qing; Xiong, Yuanquan

    2014-11-01

    A comparative study on the pyrolysis kinetics of moso bamboo has been conducted in a conventional thermogravimetric analyzer and a microwave thermogravimetric analyzer respectively. The effect of heating rate on the pyrolysis process was also discussed. The results showed that both the maximum and average reaction rates increased with the heating rate increasing. The values of activation energy increased from 58.30 to 84.22 kJ/mol with the heating rate decreasing from 135 to 60 °C/min during conventional pyrolysis. The value of activation energy was 24.5 kJ/mol for microwave pyrolysis, much lower than that for conventional pyrolysis at a similar heating rate of 160 °C/min. The pyrolysis of moso bamboo exhibited a kinetic compensation effect. The low activation energy obtained under microwave irradiation suggests that microwaves heating would be a promising method for biomass pyrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Experimental Studies on Turbulence Kinetic Energy in Confined Vortex Flows

    Institute of Scientific and Technical Information of China (English)

    L.Yan; G.H.Vatistas; 等

    2000-01-01

    Turbulence kinetic energies in confined vortex flows have been studied.The studies were based on the experiments performed in a vortex chamber,In the experiments,a Laser Doppler Anemometry(LDA) was used to perform flow measurements inside the vortex chamber,which provided the data for the kinetic energy analysis.The studies concentrated on the influences of the contraction ratio and the inlet air flow rate on the kinetic energy,and analyzed the characteristics of the kinetic energy in the confined vortex flows,including the distributions of the tangential component,radial component and total turbulence kinetic energy,In the paper,both the experimental techniques and the experimental results were presented.Based on a similarity analyis and the experimental data,an empirical scaling formula was proposed so that the tangential component of the turbulence kinetic energy was dependent only on the parameter of the contraction ratio.

  11. Kinetic study of enzymatic hydrolysis of potato starch

    Directory of Open Access Journals (Sweden)

    Óscar Fernando Castellanos Domínguez

    2010-04-01

    Full Text Available This article describes the kinetic study of potato starch enzymatic hydrolysis using soluble enzymes (Novo Nordisk. Different assays divided into four groups were used: reaction time (with which it was possible to reduce the 48-72 hour duration reported in the literature to 16 hours with comparable productivity levels; selecting the set of enzymes to be used (different types were evaluated - BAN and Termamyl as alfa-amylases during dextrinisation stage, and AMG, Promozyme and Fungamyl for sacarification reaction- identifying those presenting the best performance during hydrolysis. Reaction conditions were optimised for the process's two stages (destrinisation and sacarification. Enzyme dose, calcium cofactor concentration, pH, temperature and agitation speed were studied for the first stage. Enzyme ratio, pH and agitation speed were studied for sacarification; the latter parameter reported values having no antecedents in the literature (60 rpm and 30 rpm for first and second reactions, respectively. Michaelis Menten kinetics were calculated once conditions had been optimised, varying substrate from 10-50% P/V, obtaining km and Vmax kinetic parameters for each reaction. A kinetic model was found according to local working conditions which was able to explain potato starch conversion to glucose syrup, achieving 96 dextrose equivalents by the end of the reaction, being well within the maximum range reported in the literature (94-98. Laboratory equipment was constructed prior to carrying out assays which was able to reproduce and improve the conditions reported in the literature, making it a useful, reliable tool for use in assays returning good results.

  12. Comparative evaluation of kinetic, equilibrium and semi-equilibrium models for biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Buragohain, Buljit [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Chakma, Sankar; Kumar, Peeush [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Mahanta, Pinakeswar [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Moholkar, Vijayanand S. [Center for Energy, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India); Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati – 781 039, Assam (India)

    2013-07-01

    Modeling of biomass gasification has been an active area of research for past two decades. In the published literature, three approaches have been adopted for the modeling of this process, viz. thermodynamic equilibrium, semi-equilibrium and kinetic. In this paper, we have attempted to present a comparative assessment of these three types of models for predicting outcome of the gasification process in a circulating fluidized bed gasifier. Two model biomass, viz. rice husk and wood particles, have been chosen for analysis, with gasification medium being air. Although the trends in molar composition, net yield and LHV of the producer gas predicted by three models are in concurrence, significant quantitative difference is seen in the results. Due to rather slow kinetics of char gasification and tar oxidation, carbon conversion achieved in single pass of biomass through the gasifier, calculated using kinetic model, is quite low, which adversely affects the yield and LHV of the producer gas. Although equilibrium and semi-equilibrium models reveal relative insensitivity of producer gas characteristics towards temperature, the kinetic model shows significant effect of temperature on LHV of the gas at low air ratios. Kinetic models also reveal volume of the gasifier to be an insignificant parameter, as the net yield and LHV of the gas resulting from 6 m and 10 m riser is same. On a whole, the analysis presented in this paper indicates that thermodynamic models are useful tools for quantitative assessment of the gasification process, while kinetic models provide physically more realistic picture.

  13. Comparative evaluation of kinetic, equilibrium and semi-equilibrium models for biomass gasification

    Directory of Open Access Journals (Sweden)

    Buljit Buragohain, Sankar Chakma, Peeush Kumar, Pinakeswar Mahanta, Vijayanand S. Moholkar

    2013-01-01

    Full Text Available Modeling of biomass gasification has been an active area of research for past two decades. In the published literature, three approaches have been adopted for the modeling of this process, viz. thermodynamic equilibrium, semi-equilibrium and kinetic. In this paper, we have attempted to present a comparative assessment of these three types of models for predicting outcome of the gasification process in a circulating fluidized bed gasifier. Two model biomass, viz. rice husk and wood particles, have been chosen for analysis, with gasification medium being air. Although the trends in molar composition, net yield and LHV of the producer gas predicted by three models are in concurrence, significant quantitative difference is seen in the results. Due to rather slow kinetics of char gasification and tar oxidation, carbon conversion achieved in single pass of biomass through the gasifier, calculated using kinetic model, is quite low, which adversely affects the yield and LHV of the producer gas. Although equilibrium and semi-equilibrium models reveal relative insensitivity of producer gas characteristics towards temperature, the kinetic model shows significant effect of temperature on LHV of the gas at low air ratios. Kinetic models also reveal volume of the gasifier to be an insignificant parameter, as the net yield and LHV of the gas resulting from 6 m and 10 m riser is same. On a whole, the analysis presented in this paper indicates that thermodynamic models are useful tools for quantitative assessment of the gasification process, while kinetic models provide physically more realistic picture.

  14. Combustion Kinetic Studies of Gasolines and Surrogates

    KAUST Repository

    Javed, Tamour

    2016-11-01

    Future thrusts for gasoline engine development can be broadly summarized into two categories: (i) efficiency improvements in conventional spark ignition engines, and (ii) development of advance compression ignition (ACI) concepts. Efficiency improvements in conventional spark ignition engines requires downsizing (and turbocharging) which may be achieved by using high octane gasolines, whereas, low octane gasolines fuels are anticipated for ACI concepts. The current work provides the essential combustion kinetic data, targeting both thrusts, that is needed to develop high fidelity gasoline surrogate mechanisms and surrogate complexity guidelines. Ignition delay times of a wide range of certified gasolines and surrogates are reported here. These measurements were performed in shock tubes and rapid compression machines over a wide range of experimental conditions (650 – 1250 K, 10 – 40 bar) relevant to internal combustion engines. Using the measured the data and chemical kinetic analyses, the surrogate complexity requirements for these gasolines in homogeneous environments are specified. For the discussions presented here, gasolines are classified into three categories: (i)\\tLow octane gasolines including Saudi Aramco’s light naphtha fuel (anti-knock index, AKI = (RON + MON)/2 = 64; Sensitivity (S) = RON – MON = 1), certified FACE (Fuels for Advanced Combustion Engines) gasoline I and J (AKI ~ 70, S = 0.7 and 3 respectively), and their Primary Reference Fuels (PRF, mixtures of n-heptane and iso-octane) and multi-component surrogates. (ii)\\t Mid octane gasolines including FACE A and C (AKI ~ 84, S ~ 0 and 1 respectively) and their PRF surrogates. Laser absorption measurements of intermediate and product species formed during gasoline/surrogate oxidation are also reported. (iii)\\t A wide range of n-heptane/iso-octane/toluene (TPRF) blends to adequately represent the octane and sensitivity requirements of high octane gasolines including FACE gasoline F and G

  15. Gas Hydrate Growth Kinetics: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Remi-Erempagamo Tariyemienyo Meindinyo

    2016-12-01

    Full Text Available Gas hydrate growth kinetics was studied at a pressure of 90 bars to investigate the effect of temperature, initial water content, stirring rate, and reactor size in stirred semi-batch autoclave reactors. The mixing energy during hydrate growth was estimated by logging the power consumed. The theoretical model by Garcia-Ochoa and Gomez for estimation of the mass transfer parameters in stirred tanks has been used to evaluate the dispersion parameters of the system. The mean bubble size, impeller power input per unit volume, and impeller Reynold’s number/tip velocity were used for analyzing observed trends from the gas hydrate growth data. The growth behavior was analyzed based on the gas consumption and the growth rate per unit initial water content. The results showed that the growth rate strongly depended on the flow pattern in the cell, the gas-liquid mass transfer characteristics, and the mixing efficiency from stirring. Scale-up effects indicate that maintaining the growth rate per unit volume of reactants upon scale-up with geometric similarity does not depend only on gas dispersion in the liquid phase but may rather be a function of the specific thermal conductance, and heat and mass transfer limitations created by the limit to the degree of the liquid phase dispersion is batched and semi-batched stirred tank reactors.

  16. Kinetic study of biological hydrogen production by anaerobic fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, R. [Annamalai Univ., Chidambaram (India). Dept. of Chemical Engineering; Karunanithi, T. [Annamalai Univ., Tamilnadu (India). Dept. of Chemical Engineering

    2009-07-01

    This study examined the kinetics of batch biohydrogen production from glucose. Clostridium pasteurianum was used to produce biohydrogen by dark anaerobic fermentation. The initial substrate concentration, initial pH and temperature were optimized for biohydrogen production. The maximum production of hydrogen under optimum conditions was found to be 5.376 l/l. The kinetic parameters were determined for the optimized medium and conditions in the batch reactor. The by product was expressed as total acidic equivalent. This presentation discussed the logistic equation that was used to model the growth of the organism and described how the kinetic parameters were calculated. The Leudeking piret kinetic model was used to express the hydrogen production and substrate use because it combines both growth associated and non associated contributions. It was concluded the production of biohydrogen can be predicted well using the logistic model for cell growth kinetics and the logistic incorporated Leudeking Piret model for product and substrate utilization kinetics.

  17. Stochastic optimization-based study of dimerization kinetics

    Indian Academy of Sciences (India)

    Srijeeta Talukder; Shrabani Sen; Ralf Metzler; Suman K Banik; Pinaki Chaudhury

    2013-11-01

    We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end, we study dimerization kinetics of protein as a model system. We follow the dimerization kinetics using a stochastic simulation algorithm and combine it with three different optimization techniques (genetic algorithm, simulated annealing and parallel tempering) to obtain the rate constants involved in each reaction step. We find good convergence of the numerical scheme to the rate constants of the process. We also perform a sensitivity test on the reaction kinetic parameters to see the relative effects of the parameters for the associated profile of the monomer/dimer distribution.

  18. A Comparative Study of Teaching Comparative Education

    OpenAIRE

    2007-01-01

    The purpose of this paper is to characterize the comparative education subjects offered in different programs in different foreign universities. As a subject, comparative education has not been firmly institutionalized in education programs in Japanese universities. There was a movement which aimed at making comparative education as one of the mandatory subjects in the teacher training program, however it was not successful. To date, comparative education subject has been offered in various p...

  19. Studies on the kinetics of alcoholic fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Godia i Casablancas, F.; Casas Alvero, C.; Sola Ferrando, C.

    1984-01-01

    Yeast isolated from a must was used to ferment a medium containing 50, 98, 150, or 188 g glucose L and the kinetics of cell growth, EtOH formation, and glucose utilization were determined. The results did not agree with the results obtained using 9 different model equations. The models are therefore unsatisfactory.

  20. A STUDY ON THE CRYSTALLIZATION KINETICS OF NYLON 1010

    Institute of Scientific and Technical Information of China (English)

    CHEN Shouxi

    1997-01-01

    The kinetic behavior of isothermal and nonisothermal crystallization of nylon-1010has been studied by means of dilatometry and differential scanning calorimetry, respectively. The isothermal and nonisothermal process can be described by Avrami equation and Ozawa equation, respectively. From the experimental results the kinetic parameters of crystallization and crystalline mechanism for isothermal and nonisothermal measurements are discussed.

  1. Comparing the Effect of Open and Closed Kinetic Chain Exercises in Patients Suffering From Patellofemoral Pain Syndrome

    Directory of Open Access Journals (Sweden)

    Zahra Firoozkoohi Moghadam

    2016-11-01

    Full Text Available Introduction: Patellofemoral pain syndrome is one of the most prevalent problems in physically active people. The syndrome is a multifactorial disorder with different therapeutic approaches. Conservative treatment of the syndrome has been a crucial matter in different studies. Quadriceps muscle strengthening exercise is a recommended approach which is performed in forms of open and closed kinetic chain exercises. This study was designed to compare the efficacy of these exercises on this syndrome. Methods: Totally 30 women suffering from the syndrome aged 30-40 were randomly allocated into three groups: open, and closed kinetic chain exercises, and control group, as groups A, B, and C, respectively. Groups A and B participated in 28 sessions of exercises in a period of four weeks and group C did not do any exercise in this period. Before and after the period, pain and function of the participants were assessed using visual analog scale (VAS and Kujala patellofemoral scale, respectively. Data were analyzed using independent t test, dependent t test, and univariate variance analysis, while significance of data was determined at P < 0.05. Results: The study indicated that open kinetic chain exercises (group A for 4 weeks brought significant changes in relieving the pain along with improving the function (P = 0.001. Likewise, it was revealed a significant pain relief as well as function improvement in group B (P = 0.001. Comparing two groups illustrated that benefits of open kinetic chain exercises outweigh closed ones (P = 0.001. Conclusion: Overall, both exercises were efficient in relieving pain as well as improving function, however open kinetic chain exercises were more contributory.

  2. Insights into Coupled Folding and Binding Mechanisms from Kinetic Studies.

    Science.gov (United States)

    Shammas, Sarah L; Crabtree, Michael D; Dahal, Liza; Wicky, Basile I M; Clarke, Jane

    2016-03-25

    Intrinsically disordered proteins (IDPs) are characterized by a lack of persistent structure. Since their identification more than a decade ago, many questions regarding their functional relevance and interaction mechanisms remain unanswered. Although most experiments have taken equilibrium and structural perspectives, fewer studies have investigated the kinetics of their interactions. Here we review and highlight the type of information that can be gained from kinetic studies. In particular, we show how kinetic studies of coupled folding and binding reactions, an important class of signaling event, are needed to determine mechanisms.

  3. Kinetic Study and Thermal Decomposition Behavior of Lignite Coal

    Directory of Open Access Journals (Sweden)

    Mehran Heydari

    2015-01-01

    Full Text Available A thermogravimetric analyzer was employed to investigate the thermal behavior and extract the kinetic parameters of Canadian lignite coal. The pyrolysis experiments were conducted in temperatures ranging from 298 K to 1173 K under inert atmosphere utilizing six different heating rates of 1, 6, 9, 12, 15, and 18 K min−1, respectively. There are different techniques for analyzing the kinetics of solid-state reactions that can generally be classified into two categories: model-fitting and model-free methods. Historically, model-fitting methods are broadly used in solid-state kinetics and show an excellent fit to the experimental data but produce uncertain kinetic parameters especially for nonisothermal conditions. In this work, different model-free techniques such as the Kissinger method and the isoconversional methods of Ozawa, Kissinger-Akahira-Sunose, and Friedman are employed and compared in order to analyze nonisothermal kinetic data and investigate thermal behavior of a lignite coal. Experimental results showed that the activation energy values obtained by the isoconversional methods were in good agreement, but Friedman method was considered to be the best among the model-free methods to evaluate kinetic parameters for solid-state reactions. These results can provide useful information to predict kinetic model of coal pyrolysis and optimization of the process conditions.

  4. Planning a Kinetic and Mechanistic Study with Cerium (IV)

    Science.gov (United States)

    Hanna, Samir B.; And Others

    1976-01-01

    Presents a kinetic study that utilizes a method for varying the concentrations of the possible Ce(IV) species and computing the concentration distribution of the sulfato and hydroxo species of Ce(IV). (MLH)

  5. Kinetic Studies of Catalytic Oxidation of Cyclohexene Using ...

    African Journals Online (AJOL)

    acer

    spectroscopy and Gas chromatography-Mass spectrometry (GC/MS). Kinetics studies were ... presence alcohols and ketones while the GC/MS shows the presence of cyclohexanol (2.46%), .... Result of the GC/MS analysis: Summary of.

  6. Kinetic and thermodynamic studies of sulforaphane adsorption on macroporous resin.

    Science.gov (United States)

    Yuanfeng, Wu; Lei, Zhang; Jianwei, Mao; Shiwang, Liu; Jun, Huang; Yuru, You; Lehe, Mei

    2016-08-15

    The adsorption equilibrium, kinetic and thermodynamic of sulforaphane (SF) adsorption onto macroporous resin in aqueous phase were studied. The SP850 resin was screened as the appropriate resin for SF purification. From the equilibrium studies, the Redlich-Peterson model was found to be the best for description of the adsorption behavior of SF onto SP850 resin, followed by the Freundlich model and the Langmuir model. Batch equilibrium experiments demonstrated that, in the examined temperature range, the equilibrium adsorption capacity of SP850 resin decreased with increasing adsorption temperature. Thermodynamics studies indicated that the adsorption of SF was a physical, exothermic, and spontaneous process. The adsorption kinetics revealed that the pseudo-second-order kinetic model was suitable to characterize the kinetics of adsorption of SF onto SP850. Finally, the intra-particle diffusion model demonstrated that SF diffused quickly into macropores, and that diffusion slowed down in the meso- and micropores.

  7. Production of furfural from palm oil empty fruit bunches: kinetic model comparation

    Science.gov (United States)

    Panjaitan, J. R. H.; Monica, S.; Gozan, M.

    2017-05-01

    Furfural is a chemical compound that can be applied to pharmaceuticals, cosmetics, resins and cleaning compound which can be produced by acid hydrolysis of biomass. Indonesia’s demand for furfural in 2010 reached 790 tons that still imported mostly 72% from China. In this study, reaction kinetic models of furfural production from oil palm empty fruit bunches with submitting acid catalyst at the beginning of the experiment will be determine. Kinetic data will be obtained from hydrolysis of empty oil palm bunches using sulfuric acid catalyst 3% at temperature 170°C, 180°C and 190°C for 20 minutes. From this study, the kinetic model to describe the production of furfural is the kinetic model where generally hydrolysis reaction with an acid catalyst in hemicellulose and furfural will produce the same decomposition product which is formic acid with different reaction pathways. The activation energy obtained for the formation of furfural, the formation of decomposition products from furfural and the formation of decomposition products from hemicellulose is 8.240 kJ/mol, 19.912 kJ/mol and -39.267 kJ / mol.

  8. Comparative uptake kinetics and transport of cadmium and phosphate in Phleum pratense-Glomus deserticolum associations

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, P.T.; Kapustka, L.A. (Miami Univ., Oxford, OH (United States))

    1993-01-01

    Mycorrhizal plants (timothy grass, Phleum pretense with Glomus deserticolum) were compared to nonmycorrhizal timothy grass to determine the effect of the mycorrhizal condition on the uptake and transport of cadmium. Companion experiments were conducted to ascertain phosphate uptake kinetics of mycorrhizal and nonmycorrhizal plants. Divalent cation competition experiments also were employed in this study. Comparisons of the high-affinity uptake mechanisms between mycorrhizal and nonmycorrhizal plants identified higher levels of phosphate uptake were due to an increase in the number of uptake sites rather than to differences in affinity. The respective values for K[sub m] for high-affinity phosphate uptake were 2.5 [plus minus] 1.3 [mu]MP (mycorrhizal) and 3.4 [plus minus] 1.3 [mu]MP (nonmycorrhizal), but these values were not statistically different at the [alpha] = 0.05 level. High-affinity Cd[sup 2+] uptake differed significantly between mycorrhizal (4.5 [plus minus] 2.8 [mu]M) and nonmycorrhizal (2.8 [plus minus] 1.1 [mu]M) plants. Presence of Ca[sup 2+] at 1.0mM concentration conferred considerable competitive protection in both the mycorrhizal and the nonmycorrhizal conditions. The effect of Ca[sup 2+] was an approximate fourfold increase in the respective K[sub m] values.

  9. Comparative Analysis of Thermal Behavior, Isothermal Crystallization Kinetics and Polymorphism of Palm Oil Fractions

    Directory of Open Access Journals (Sweden)

    Bing Li

    2013-01-01

    Full Text Available Thermal behavior of palm stearin (PS and palm olein (PO was explored by monitoring peak temperature transitions by differential scanning calorimetry (DSC. The fatty acid composition (FAC, isothermal crystallization kinetics studied by pulsed Nuclear Magnetic Resonance (pNMR and isothermal microstructure were also compared. The results indicated that the fatty acid composition had an important influence on the crystallization process. PS and PO both exhibited more multiple endotherms than exotherms which showed irregular peak shapes. An increasing in cooling rate, generally, was associated with an increase in peak size. Application of the Avaimi equation to isothermal crystallization of PS and PO revealed different nucleation and growth mechanisms based on the Avrami exponents. PS quickly reached the end of crystallization because of more saturated triacylglycerol (TAG. The Avrami index of PS were the same as PO under the same isothermal condition at lower temperatrue, indicating that the crystallization mechanism of the two samples based on super-cooling state were the same. According to the polarized light microscope (PLM images, crystal morphology of PS and PO was different. With the temperature increased, the structure of crystal network of both PS and PO gradually loosened.

  10. Comparative Kinetic Analysis of Closed-Ended and Open-Ended Porous Sensors

    Science.gov (United States)

    Zhao, Yiliang; Gaur, Girija; Mernaugh, Raymond L.; Laibinis, Paul E.; Weiss, Sharon M.

    2016-09-01

    Efficient mass transport through porous networks is essential for achieving rapid response times in sensing applications utilizing porous materials. In this work, we show that open-ended porous membranes can overcome diffusion challenges experienced by closed-ended porous materials in a microfluidic environment. A theoretical model including both transport and reaction kinetics is employed to study the influence of flow velocity, bulk analyte concentration, analyte diffusivity, and adsorption rate on the performance of open-ended and closed-ended porous sensors integrated with flow cells. The analysis shows that open-ended pores enable analyte flow through the pores and greatly reduce the response time and analyte consumption for detecting large molecules with slow diffusivities compared with closed-ended pores for which analytes largely flow over the pores. Experimental confirmation of the results was carried out with open- and closed-ended porous silicon (PSi) microcavities fabricated in flow-through and flow-over sensor configurations, respectively. The adsorption behavior of small analytes onto the inner surfaces of closed-ended and open-ended PSi membrane microcavities was similar. However, for large analytes, PSi membranes in a flow-through scheme showed significant improvement in response times due to more efficient convective transport of analytes. The experimental results and theoretical analysis provide quantitative estimates of the benefits offered by open-ended porous membranes for different analyte systems.

  11. Bimetal Adsorption by Cottonseed Carbon: Equlibrium and Kinetic Studies

    Directory of Open Access Journals (Sweden)

    K. Srinivasan

    2009-01-01

    Full Text Available The simultaneous adsorption of Pb(II and Hg(II on cottonseed carbon (CSC was employed for the removal of these metals from wastewater. The influence of various factors such as agitation time, pH and carbon dosage on the adsorption capacity has been studied. Langmuir and Freundlich equation could be used to interpret adsorption data. Sorption kinetics has indicated that reversible first order kinetics model could be applied with film diffusion as the controlling mechanism.

  12. Theoretical studies on kinetics of singlet oxygen in nonthermal plasma

    Science.gov (United States)

    Frolov, Mikhail P.; Ionin, Andrei A.; Kotkov, Andrei A.; Kochetov, Igor V.; Napartovich, Anatolii P.; Podmarkov, Yurii P.; Seleznev, Leonid V.; Sinitsyn, Dmitrii V.; Vagin, Nikolai P.; Yuryshev, Nikolay N.

    2004-09-01

    An idea to replace singlet delta oxygen (SDO) generator working with wet chemistry by electric discharge generator has got much attention last years. Different kinds of discharge were examined for this purpose, but without a great success. The existing theoretical models are not validated by well-characterized experimental data. To describe complicated kinetics in gas discharge with oxygen one needs to know in detail processes involving numerous electronic excited oxygen molecules and atoms. To gain new knowledge about these processes experimental studies were made on electric discharge properties in gas mixture flow with independent control of inlet SDO concentration. The theoretical model extended to include minor additives like oxygen atoms, water molecules, ozone was developed. Comparison with careful experimental measurements of electric characteristics along with gas composition allows us to verify the model and make theoretical predictions more reliable. Results of numerical simulations using this model for an electron-beam sustained discharge are reported and compared with the experimental data.

  13. Photosynthetic membrane development studied using picosecond fluorescence kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Karukstis, K.K.; Sauer, K.

    1983-01-01

    Using measurements of the kinetics of chlorophyll a fluorescence emission, the development of the photosynthetic membrane during etioplast-to-chloroplast differentiation was investigated. Tthe chlorophyll fluorescence decay kinetics of pea chloroplasts from plants grown under intermittent (2 min light-118 min dark) and continuous light regimes were monitored with a single-proton timing system with picosecond resolution. The changes in the fluorescence yields and decay kinetics were associated with known structural and organizational developmental phenomena in the chloroplast. This correlation provides a more detailed assignment of the origins of the fluorescence decay components than has been previously obtained by studying only mature chloroplasts. In particular, the analysis of the variable kinetics and multiexponential character of the fluorescence emission during thylakoid development focuses on the organization of photosynthetic units and the degree of communication between reaction centers in the same photosystem. These results further demonstrate that the age of etiolated tissue is critical to plastid development.

  14. Kinetics of ethylcyclohexane pyrolysis and oxidation: An experimental and detailed kinetic modeling study

    KAUST Repository

    Wang, Zhandong

    2015-07-01

    Ethylcyclohexane (ECH) is a model compound for cycloalkanes with long alkyl side-chains. A preliminary investigation on ECH (Wang et al., Proc. Combust. Inst., 35, 2015, 367-375) revealed that an accurate ECH kinetic model with detailed fuel consumption mechanism and aromatic growth pathways, as well as additional ECH pyrolysis and oxidation data with detailed species concentration covering a wide pressure and temperature range are required to understand the ECH combustion kinetics. In this work, the flow reactor pyrolysis of ECH at various pressures (30, 150 and 760Torr) was studied using synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (PIMS) and gas chromatography (GC). The mole fraction profiles of numerous major and minor species were evaluated, and good agreement was observed between the PIMS and GC data sets. Furthermore, a fuel-rich burner-stabilized laminar premixed ECH/O2/Ar flame at 30Torr was studied using synchrotron VUV PIMS. A detailed kinetic model for ECH high temperature pyrolysis and oxidation was developed and validated against the pyrolysis and flame data performed in this work. Further validation of the kinetic model is presented against literature data including species concentrations in jet-stirred reactor oxidation, ignition delay times in a shock tube, and laminar flame speeds at various pressures and equivalence ratios. The model well predicts the consumption of ECH, the growth of aromatics, and the global combustion properties. Reaction flux and sensitivity analysis were utilized to elucidate chemical kinetic features of ECH combustion under various reaction conditions. © 2015 The Combustion Institute.

  15. Study on kinetic model of microwave thermocatalytic treatment of biomass tar model compound.

    Science.gov (United States)

    Anis, Samsudin; Zainal, Z A

    2014-01-01

    Kinetic model parameters for toluene conversion under microwave thermocatalytic treatment were evaluated. The kinetic rate constants were determined using integral method based on experimental data and coupled with Arrhenius equation for obtaining the activation energies and pre-exponential factors. The model provides a good agreement with the experimental data. The kinetic model was also validated with standard error of 3% on average. The extrapolation of the model showed a reasonable trend to predict toluene conversion and product yield both in thermal and catalytic treatments. Under microwave irradiation, activation energy of toluene conversion was lower in the range of 3-27 kJ mol(-1) compared to those of conventional heating reported in the literatures. The overall reaction rate was six times higher compared to conventional heating. As a whole, the kinetic model works better for tar model removal in the absence of gas reforming within a level of reliability demonstrated in this study.

  16. Kinetic Uptake Studies of Powdered Materials in Solution

    Directory of Open Access Journals (Sweden)

    Mohamed H. Mohamed

    2015-06-01

    Full Text Available Challenges exist for the study of time dependent sorption processes for heterogeneous systems, especially in the case of dispersed nanomaterials in solvents or solutions because they are not well suited to conventional batch kinetic experiments. In this study, a comparison of batch versus a one-pot setup in two variable configurations was evaluated for the study of uptake kinetics in heterogeneous (solid/solution systems: (i conventional batch method; (ii one-pot system with dispersed adsorbent in solution with a semi-permeable barrier (filter paper or dialysis tubing for in situ sampling; and (iii one-pot system with an adsorbent confined in a semi-permeable barrier (dialysis tubing or filter paper barrier with ex situ sampling. The sorbent systems evaluated herein include several cyclodextrin-based polyurethane materials with two types of phenolic dyes: p-nitrophenol and phenolphthalein. The one-pot kinetics method with in situ (Method ii or ex situ (Method iii sampling described herein offers significant advantages for the study of heterogeneous sorption kinetics of highly dispersed sorbent materials with particles sizes across a range of dimensions from the micron to nanometer scale. The method described herein will contribute positively to the development of advanced studies for heterogeneous sorption processes where an assessment of the relative uptake properties is required at different experimental conditions. The results of this study will be advantageous for the study of nanomaterials with significant benefits over batch kinetic studies for a wide range of heterogeneous sorption processes.

  17. Comparative Kinetic Methods used for the Therapy of Idiopathic Scoliosis in Adolescents

    OpenAIRE

    Elena AMARICĂI

    2013-01-01

    Scoliosis is one of the most common axial deviations of the spine. Because of its incidence and the fact that, with the evolution of technology, adolescents spend increasingly more time sitting at desk, adopting positions often incorrect, this paper aims to study the evolution of adolescent patients diagnosed with scoliosis using different kinetic methods of treatment. Another objective is to highlight the most effective method of treatment in terms of overall rehabilitation period, the time ...

  18. Implementing atomic force microscopy (AFM) for studying kinetics of gold nanoparticle's growth

    DEFF Research Database (Denmark)

    Georgiev, P.; Bojinova, A.; Kostova, B.

    2013-01-01

    In a novel experimental approach Atomic Force Microscopy (AFM) was applied as a tool for studying the kinetics of gold nanoparticle growth. The gold nanoparticles were obtained by classical Turkevich citrate synthesis at two different temperatures. From the analysis of AFM images during the synth......In a novel experimental approach Atomic Force Microscopy (AFM) was applied as a tool for studying the kinetics of gold nanoparticle growth. The gold nanoparticles were obtained by classical Turkevich citrate synthesis at two different temperatures. From the analysis of AFM images during...... approach. We also compared AFM experimental data with Dynamic Light Scattering (DLS) and with Transmission Electron Microscopy (TEM) data. The experimental data from all the applied methods were fitted with two step Finke-Watzky kinetics model and the corresponding kinetics constants were obtained...

  19. Kinetic studies of cellulose enzymatic hydrolysis from pretreated corn cob

    Science.gov (United States)

    Stevanie, Jeannie; Kartawiria, Irvan; Abimanyu, Haznan

    2017-01-01

    Successful utilization of corn cob biomass as raw material in bioethanol production is depending on the hydrolysis process where high level of β-cellulose is converted into glucose. Enzymatic hydrolysis is the common process for this purpose. This study is focusing on the evaluation of hydrolysis of pre-treated corn cob using Novozymes Cellic ® C-Tec2 and H-Tec2 enzymes to obtain the optimum reaction condition and its general reaction kinetics. The corn cob used was pretreated using 10% of NaOH solution. Hydrolysis reactions were conducted in 250 ml Erlenmeyer flask for 72 hour using mixture of C-Tec2 and H-Tec2 enzymes at the fixed ratio of 5:1 and glucose concentration were measured using HPLC. Reaction temperature of 40°C and quantity of 0.5 ml enzyme solution per gram substrate gives the highest reaction rate (0.0123 gram of glucose/gram sample.h) with the glucose yield being 0.089 g glucose/ g substrate. Total conversion of cellulose observed was 11.91 %. Corn cob hydrolysis using C-Tec2 and H-Tec2 enzymes also result in xylose (0.0202 g/g substrate), which can also contribute to bioethanol productivity in further fermentation process. The reaction is following zero order kinetics for the first 8 hours and reaches maximum yield within 10 hours; significantly shorter compared to previous studies of cellulosic material hydrolysis that may take up to 72 hour to complete. Prolonging the hydrolysis of pre-treated corn cob more than 24 hour gives no significant increase in glucose conversion and yield. Hydrolysis temperature range of 40°C to 60°C is in accordance with the manufacturer recommendation for the purpose; however the decrease of reaction rate is observable at temperature 50°C or higher.

  20. Kinetic Study on Pyrolysis of Oil Palm Frond

    Science.gov (United States)

    Soon, V. S. Y.; Chin, B. L. F.; Lim, A. C. R.

    2016-03-01

    The pyrolysis of oil palm frond is studied using thermogravimetric analysis (TGA) equipment. The present study investigates the thermal degradation behaviour and determination of the kinetic parameters such as the activation energy (EA ) and pre-exponential factor (A) values of oil palm frond under pyrolysis condition. The kinetic data is produced based on first order rate of reaction. In this study, the experiments are conducted at different heating rates of 10, 20, 30, 40 and 50 K/min in the temperature range of 323-1173 K under non-isothermal condition. Argon gas is used as an inert gas to remove any entrapment of gases in the TGA equipment.

  1. Kinetic and Related Determinants of Plasma Triglyceride Concentration in Abdominal Obesity: Multicenter Tracer Kinetic Study.

    Science.gov (United States)

    Borén, Jan; Watts, Gerald F; Adiels, Martin; Söderlund, Sanni; Chan, Dick C; Hakkarainen, Antti; Lundbom, Nina; Matikainen, Niina; Kahri, Juhani; Vergès, Bruno; Barrett, P Hugh R; Taskinen, Marja-Riitta

    2015-10-01

    Patients with obesity and diabetes mellitus have increased risk of cardiovascular disease. A major cause is an atherogenic dyslipidemia related primarily to elevated plasma concentrations of triglyceride-rich lipoproteins. The aim of this study was to clarify determinants of plasma triglyceride concentration. We focused on factors that predict the kinetics of very-low density lipoprotein 1 (VLDL1) triglycerides. A multicenter study using dual stable isotopes (deuterated leucine and glycerol) and multicompartmental modeling was performed to elucidate the kinetics of triglycerides and apoB in VLDL1 in 46 subjects with abdominal obesity and additional cardiometabolic risk factors. Results showed that plasma triglyceride concentrations were dependent on both the secretion rate (r=0.44, Ptriglycerides and VLDL1-apoB. Liver fat mass was independently and directly associated with secretion rates of VLDL1-triglycerides (r=0.56, Ptriglycerides (r=0.48, Ptriglyceride concentrations in abdominal obesity are determined by the kinetics of VLDL1 subspecies, catabolism being mainly dependent on apoC-III concentration and secretion on liver fat content. Reduction in liver fat and targeting apoC-III may be an effective approach for correcting triglyceride metabolism atherogenic dyslipidemia in obesity. © 2015 American Heart Association, Inc.

  2. Comparative Kinetic Methods used for the Therapy of Idiopathic Scoliosis in Adolescents

    Directory of Open Access Journals (Sweden)

    Elena AMARICĂI

    2013-12-01

    Full Text Available Scoliosis is one of the most common axial deviations of the spine. Because of its incidence and the fact that, with the evolution of technology, adolescents spend increasingly more time sitting at desk, adopting positions often incorrect, this paper aims to study the evolution of adolescent patients diagnosed with scoliosis using different kinetic methods of treatment. Another objective is to highlight the most effective method of treatment in terms of overall rehabilitation period, the time spent by the patient in the rehabilitation centre and the preservation of scoliosis correction. 9 adolescents patients (aged between 14 and 17 years with idiopathic scoliosis were divided into three groups based on the followed kinetic method. Three patients underwent a physical therapy program based on the conventional Klapp and Cotrel method, three patients performed Schroth method, and the other three patients performed Vojta method. All patients were monitored for 6 months. They followed a certain rehabilitation therapy in a specialized centre under the guidance of specialized therapist. Height, weight and scoliosis curvature (measured by the Cobb angle were assessed at the beginning of the program and after 6 months of kinetic program. The small number of patients in each group could not issue conclusions regarding the statistical efficiency of the three methods of therapy. However, besides the conventional therapy, both Schroth method and Vojta method represent possibilities to treat the adolescent patients with idiopathic scoliosis.

  3. Comparing kinetic Monte Carlo and thin-film modeling of transversal instabilities of ridges on patterned substrates

    Science.gov (United States)

    Tewes, Walter; Buller, Oleg; Heuer, Andreas; Thiele, Uwe; Gurevich, Svetlana V.

    2017-03-01

    We employ kinetic Monte Carlo (KMC) simulations and a thin-film continuum model to comparatively study the transversal (i.e., Plateau-Rayleigh) instability of ridges formed by molecules on pre-patterned substrates. It is demonstrated that the evolution of the occurring instability qualitatively agrees between the two models for a single ridge as well as for two weakly interacting ridges. In particular, it is shown for both models that the instability occurs on well defined length and time scales which are, for the KMC model, significantly larger than the intrinsic scales of thermodynamic fluctuations. This is further evidenced by the similarity of dispersion relations characterizing the linear instability modes.

  4. Label-free solution-based kinetic study of aptamer-small molecule interactions by kinetic capillary electrophoresis with UV detection revealing how kinetics control equilibrium.

    Science.gov (United States)

    Bao, Jiayin; Krylova, Svetlana M; Reinstein, Oren; Johnson, Philip E; Krylov, Sergey N

    2011-11-15

    Here we demonstrate a label-free solution-based approach for studying the kinetics of biopolymer-small molecule interactions. The approach utilizes kinetic capillary electrophoresis (KCE) separation and UV light absorption detection of the unlabeled small molecule. In this proof-of-concept work, we applied KCE-UV to study kinetics of interaction between a small molecule and a DNA aptamer. From the kinetic analysis of a series of aptamers, we found that dissociation rather than binding controls the stability of the complex. Because of its label-free features and generic nature, KCE-UV promises to become a practical tool for challenging kinetic studies of biopolymer-small molecule interactions.

  5. Modeling vancomycin release kinetics from microporous calcium phosphate ceramics comparing static and dynamic immersion conditions.

    Science.gov (United States)

    Gbureck, Uwe; Vorndran, Elke; Barralet, Jake E

    2008-09-01

    The release kinetics of vancomycin from calcium phosphate dihydrate (brushite) matrices and polymer/brushite composites were compared using different fluid replacement regimes, a regular replacement (static conditions) and a continuous flow technique (dynamic conditions). The use of a constantly refreshed flowing resulted in a faster drug release due to a constantly high diffusion gradient between drug loaded matrix and the eluting medium. Drug release was modeled using the Weibull, Peppas and Higuchi equations. The results showed that drug liberation was diffusion controlled for the ceramics matrices, whereas ceramics/polymer composites led to a mixed diffusion and degradation controlled release mechanism. The continuous flow technique was for these materials responsible for a faster release due to an accelerated polymer degradation rate compared with the regular fluid replacement technique.

  6. Comparative dissolution kinetics of biogenic and chemogenic uraninite under oxidizing conditions in the presence of carbonate

    Science.gov (United States)

    Ulrich, Kai-Uwe; Ilton, Eugene S.; Veeramani, Harish; Sharp, Jonathan O.; Bernier-Latmani, Rizlan; Schofield, Eleanor J.; Bargar, John R.; Giammar, Daniel E.

    2009-10-01

    The long-term stability of biogenic uraninite with respect to oxidative dissolution is pivotal to the success of in situ bioreduction strategies for the subsurface remediation of uranium legacies. Batch and flow-through dissolution experiments were conducted along with spectroscopic analyses to compare biogenic uraninite nanoparticles obtained from Shewanella oneidensis MR-1 and chemogenic UO 2.00 with respect to their equilibrium solubility, dissolution mechanisms, and dissolution kinetics in water of varied oxygen and carbonate concentrations. Both materials exhibited a similar intrinsic solubility of ˜10 -8 M under reducing conditions. The two materials had comparable dissolution rates under anoxic as well as oxidizing conditions, consistent with structural bulk homology of biogenic and stoichiometric uraninite. Carbonate reversibly promoted uraninite dissolution under both moderately oxidizing and reducing conditions, and the biogenic material yielded higher surface area-normalized dissolution rates than the chemogenic. This difference is in accordance with the higher proportion of U(V) detected on the biogenic uraninite surface by means of X-ray photoelectron spectroscopy. Reasonable sources of a stable U(V)-bearing intermediate phase are discussed. The observed increase of the dissolution rates can be explained by carbonate complexation of U(V) facilitating the detachment of U(V) from the uraninite surface. The fraction of surface-associated U(VI) increased with dissolved oxygen concentration. Simultaneously, X-ray absorption spectra showed conversion of the bulk from UO 2.0 to UO 2+x. In equilibrium with air, combined spectroscopic results support the formation of a near-surface layer of approximate composition UO 2.25 (U 4O 9) coated by an outer layer of U(VI). This result is in accordance with flow-through dissolution experiments that indicate control of the dissolution rate of surface-oxidized uraninite by the solubility of metaschoepite under the tested

  7. Kinetic Study of MOCVD Ⅲ-Ⅴ Quaternary Antimonides

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The kinetics of MOCVD GaInAsSb and AlGaAsSb was studied by the growth rate as a function of growth temperature and partial pressure of Ⅲ and Ⅴ MO species. The diffusion theory was used to explain the mass transport processes in MOCVD Ⅲ-Ⅴ quaternary antimonides. On the basis of the discussion about their growth kinetics and epilayer properties, the good quality multi-epilayers of these two quaternary antimonides and their photodetectors and arrays with wavelength of 1.8~2.3 μm and detectivities of D*>109 cm Hz1/2 W-1 were obtained.

  8. STUDY ON THERMAL DECOMPOSITION KINETICS OF URUSHIOL METAL CHELATE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    HU Binghuan; CHEN Riyao; LIN Jinhuo; CHEN Wending

    1994-01-01

    The thermal decomposition kinetics of urushiol-Cu, urushiol-Nd and urushiol-Ti chelate polymers has been studied by non-isothermal thermogravimetry. The results suggest that the thermal decomposition kinetics of three chelate polymers are all of first order. Their average activation energy values of the thermal decomposition calculated by Ozawa-(Ⅰ) method are 110.79,136.98 and 163.64 kJ mol-1respectively,which increase linearly with the metal valence of the metal chelate polymers

  9. Postcoital Sperm Assessment Comparative Study.

    Science.gov (United States)

    Pelekanos, Michael J

    2015-11-01

    This postcoital sperm assessment study was performed over a 10 month time period (November 2014-August 2015). Fifteen couples enrolled in the study. The study was a non-blinded, non-randomized, single-center comparison study comparing The Stork® OTC (Rinovum Women's Health, Monroeville, PA) to natural intercourse (NI), using the subjects as their own control/baseline. This was an efficacy study designed to compare the number of sperm in the cervical mucus following the use of The Stork OTC conception aid with the number of sperm in the cervical mucus following natural intercourse. Subjects used both The Stork OTC conception system and the natural intercourse method to evaluate concentrations of sperm in the cervical mucus. Post-coital test (PCT) data was collected demonstrating higher concentrations of sperm within the cervical mucus with The Stork OTC conception system versus natural intercourse for 85% of test subjects in this study. Of the 15 couples enrolled in the study, 2 were lost to follow-up. Mean age for male subjects was 31.7 +/ 5.4 years of age and mean age for female subjects was 29.7+/- 5.4. The average sperm score value of the 85% of test subjects with higher sperm concentrations from The Stork OTC was 3.23 times the score value of sperm concentration compared to natural intercourse. The remaining 15% of test subjects showed no change in sperm score value between The Stork OTC and natural intercourse.

  10. A microfluidic method to study demulsification kinetics

    NARCIS (Netherlands)

    Krebs, T.; Schroën, C.G.P.H.; Boom, R.M.

    2012-01-01

    We present the results of experiments studying droplet coalescence in a dense layer of emulsion droplets using microfluidic circuits. The microfluidic structure allows direct observation of collisions and coalescence events between oil droplets dispersed in water. The coalescence rate of a flowing h

  11. Kinetic-energy functionals studied by surface calculations

    DEFF Research Database (Denmark)

    Vitos, Levente; Skriver, Hans Lomholt; Kollár, J.

    1998-01-01

    The self-consistent jellium model of metal surfaces is used to study the accuracy of a number of semilocal kinetic-energy functionals for independent particles. It is shown that the poor accuracy exhibited by the gradient expansion approximation and most of the semiempirical functionals in the low...

  12. Kinetic Study of the Heck Reaction: An Interdisciplinary Experiment

    Science.gov (United States)

    Gozzi, Christel; Bouzidi, Naoual

    2008-01-01

    The aim of this experiment is to study and calculate the kinetic constant of a Heck reaction: the arylation of but-3-en-2-ol by iodobenzene catalyzed by palladium acetate in presence of triethylamine in DMF. The reaction leads to a mixture of two ketones. Students use GC analysis to quantify reagents and products of reaction. They control the…

  13. Raman scattering study of glass crystallization kinetics

    Science.gov (United States)

    Balkanski, M.; Haro, E.; Espinosa, G. P.; Phillips, J. C.

    1984-08-01

    Laser induced glass-crystalline transition is studied by light scattering. Three significant effects are observed depending on the incident laser energy density: (i) Spectral band narrowing indicating cluster enlargement constitutes a precursor effect, (ii) an intensity increase effect indicates a rapid rise of the density of clusters attaining microcrystalline size and (iii) a dynamical reversal effect indicative of glass-crystalline instability. Cluster volume and crystallization appear as separate but related threshold phenomena.

  14. Hidration kinetics study of tlie mixed cements

    OpenAIRE

    Duque Fernández, Gabriel . L; Díaz Quintanilla, David; Zapata Sierra, Manuel; Rubio Frías, Ester

    1993-01-01

    A study of the hydration process of cements with 10% and 20% addition of a tuff from "Las Carolinas" quarry (Cienfuegos, Cuba) by different methods was done. The results obtained by different methods showed a good agreement. It was proved an increment of the hydration products, an acceleration of alite hydration and a swelling of the fixed water in mixed cements. The resistance of the cement with 10% addition is similar to that of the pure cement for ages of 28 days, whereas with 20% addition...

  15. Hidration kinetics study of tlie mixed cements

    Directory of Open Access Journals (Sweden)

    Duque Fernández, Gabriel . L

    1993-09-01

    Full Text Available A study of the hydration process of cements with 10% and 20% addition of a tuff from "Las Carolinas" quarry (Cienfuegos, Cuba by different methods was done. The results obtained by different methods showed a good agreement. It was proved an increment of the hydration products, an acceleration of alite hydration and a swelling of the fixed water in mixed cements. The resistance of the cement with 10% addition is similar to that of the pure cement for ages of 28 days, whereas with 20% addition they were similar only after 180 days.

    Se hizo un estudio por diferentes métodos de la hidratación de cementos con 10% y 20% de adición de una toba del yacimiento "Las Carolinas", en la provincia de Cien fuegos (Cuba. Hubo una buena correspondencia entre las diferentes técnicas de análisis utilizadas, comprobándose que en los cementos mezclados se incrementan los productos de hidratación, se acelera la hidratación de la alita, aumenta el contenido de agua fija, así como que la resistencia del cemento, con hasta 10% de adición, es similar al cemento puro para tiempos de curado de 3 y 28 días, mientras que con 20% de adición sólo se igualan después de los 180 días.

  16. Formation of magnetic filaments: A kinetic study

    Science.gov (United States)

    Martínez-Pedrero, F.; Tirado-Miranda, M.; Schmitt, A.; Callejas-Fernández, J.

    2007-07-01

    In order to form magnetic filaments or chains, aqueous suspensions of superparamagnetic colloidal particles were aggregated under the action of an external magnetic field in the presence of different amounts of an indifferent 1:1 electrolyte (KBr). This allowed the influence of the anisotropic magnetic and isotropic electrostatic interactions on the aggregation behavior of these electric double-layered magnetic particles to be studied. Dynamic light scattering was used for monitoring the average diffusion coefficient of the magnetic filaments formed. Hydrodynamic equations were employed for obtaining the average chain lengths from the experimental mean diffusion coefficients. The results show that, for the same exposure time to the magnetic field, the average filament size is monotonously related to the amount of electrolyte added. The chain growth behavior was found to follow a power law with a similar exponent for all electrolyte concentrations used in this work. The time evolution of the average filament size can be rescaled such that all the curves collapse on a single master curve. Since the electrolyte added does not have any effect on the scaling behavior, the mechanism of aggregation seems to be completely controlled by the dipolar interaction. However, electrolyte addition not only controls the range of the total interaction between the particles, but also enhances the growth rate of the aggregation process. Taking into account the anisotropic character of these aggregation processes we propose a kernel that depends explicitly on the range of the dipolar interaction. The corresponding solutions of the Smoluchowski equation combined with theoretical models for the diffusion and light scattering by rigid rods reproduce the measured time evolution of the average perpendicular aggregate diffusion coefficient quite satisfactorily.

  17. A diaphragmless shock tube for high temperature kinetic studies.

    Science.gov (United States)

    Tranter, Robert S; Giri, Binod R

    2008-09-01

    A novel, diaphragmless shock tube (DFST) has been developed for use in high temperature chemical kinetic studies. The design of the apparatus is presented along with performance data that demonstrate the range and reproducibility of reaction conditions that can be generated. The ability to obtain data in the fall off region, confined to much narrower pressure ranges than can be obtained with a conventional shock tube is shown, and results from laser schlieren densitometry experiments on the unimolecular dissociation of phenyl iodide (P(2)=57+/-9 and 122+/-7 torr, T(2)=1250-1804 K) are presented. These are compared with results similar to those that would be obtained from a classical shock tube and the implications for extrapolation by theoretical methods are discussed. Finally, the use of the DFST with an online mass spectrometer to create reproducible experiments that can be signal averaged to improve signal/noise and the quality of mass peaks is demonstrated; something that is not possible with a conventional shock tube where each experiment has to be considered unique.

  18. Detailed kinetic modeling study of n-pentanol oxidation

    KAUST Repository

    Heufer, Karl Alexander

    2012-10-18

    To help overcome the world\\'s dependence upon fossil fuels, suitable biofuels are promising alternatives that can be used in the transportation sector. Recent research on internal combustion engines shows that short alcoholic fuels (e.g., ethanol or n-butanol) have reduced pollutant emissions and increased knock resistance compared to fossil fuels. Although higher molecular weight alcohols (e.g., n-pentanol and n-hexanol) exhibit higher reactivity that lowers their knock resistance, they are suitable for diesel engines or advanced engine concepts, such as homogeneous charge compression ignition (HCCI), where higher reactivity at lower temperatures is necessary for engine operation. The present study presents a detailed kinetic model for n-pentanol based on modeling rules previously presented for n-butanol. This approach was initially validated using quantum chemistry calculations to verify the most stable n-pentanol conformation and to obtain C-H and C-C bond dissociation energies. The proposed model has been validated against ignition delay time data, speciation data from a jet-stirred reactor, and laminar flame velocity measurements. Overall, the model shows good agreement with the experiments and permits a detailed discussion of the differences between alcohols and alkanes. © 2012 American Chemical Society.

  19. A Study on the Kinetic Characteristics of Transmutation Process Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae seon; Huh, Chang Wook; Kim, Doh Hyung [Seoul National University, Seoul (Korea, Republic of)

    1997-07-01

    The purpose of this study is to examine the transient heat transfer characteristics of liquid mental as the coolant used in accelerator-driven transmutation process reactor which is related the disposal of high-level radioactive nuclide. At current stage, the accelerator-driven transmutation process is investigated as the most appropriate method among many transmutation process methods. In this study, previous research works are investigated especially about the thermal hydraulics and kinetic behavior of coolant material including heat transfer of coolant in transmutation process reactor. A study on the heat transfer characteristics of liquid metal is performed based on the thermal hydraulic kinetic characteristics of liquid metal reactor which uses liquid metal coolant. Based on this study, the most appropriate material for the coolant of transmutation reactor will be recommended. 53 refs., 15 tabs., 33 figs. (author)

  20. Computational Kinetic Study for the Unimolecular Decomposition Pathways of Cyclohexanone.

    Science.gov (United States)

    Zaras, Aristotelis M; Dagaut, Philippe; Serinyel, Zeynep

    2015-07-16

    There has been evidence lately that several endophytic fungi can convert lignocellulosic biomass into ketones among other oxygenated compounds. Such compounds could prove useful as biofuels for internal combustion engines. Therefore, their combustion properties are of high interest. Cyclohexanone was identified as an interesting second-generation biofuel ( Boot , M. ; et al. Cyclic Oxygenates: A New Class of Second-Generation Biofuels for Diesel Engines? Energy Fuels 2009 , 23 , 1808 - 1817 ; Klein-Douwel , R. J. H. ; et al. Soot and Chemiluminescence in Diesel Combustion of Bio-Derived, Oxygenated and Reference Fuels . Proc. Combust. Inst. 2009 , 32 , 2817 - 2825 ). However, until recently ( Serinyel , Z. ; et al. Kinetics of Oxidation of Cyclohexanone in a Jet- Stirred Reactor: Experimental and Modeling . Proc. Combust. Inst. 2014 ; DOI: 10.1016/j.proci.2014.06.150 ), no previous studies on the kinetics of oxidation of that fuel could be found in the literature. In this work, we present the first theoretical kinetic study of the unimolecular decomposition pathways of cyclohexanone, a cyclic ketone that could demonstrate important fuel potential. Using the quantum composite G3B3 method, we identified six different decomposition pathways for cyclohexanone and computed the corresponding rate constants. The rate constants were calculated using the G3B3 method coupled with Rice-Ramsperger-Kassel-Marcus theory in the temperature range of 800-2000 K. Our calculations show that the kinetically more favorable channel for thermal decomposition is pathway 2 that produces 1,3-butadien-2-ol, which in turn can isomerize easily to methyl vinyl ketone through a small barrier. The results presented here can be used in a future kinetic combustion mechanism.

  1. Interconversion kinetic studies of betamethasone acetate polymorphs in water.

    Science.gov (United States)

    Ke, Xue; Ping, QiNeng; Liao, ZhengGen

    2006-10-01

    This study assessed the effect of polymers on the transformation of polymorphs of betamethasone acetate (BA) when suspended in water. The results showed that the polymers, in particular HPMC E5, retarded the transition of the forms Ialpha and Ibeta. However, the form Ialpha, as the metastable form, with the aid of HPMC E5, was preferred for BA suspension preparation through kinetic studies, while the form Ibeta was not suitable due to its instability in water.

  2. [Comparative studies of face recognition].

    Science.gov (United States)

    Kawai, Nobuyuki

    2012-07-01

    Every human being is proficient in face recognition. However, the reason for and the manner in which humans have attained such an ability remain unknown. These questions can be best answered-through comparative studies of face recognition in non-human animals. Studies in both primates and non-primates show that not only primates, but also non-primates possess the ability to extract information from their conspecifics and from human experimenters. Neural specialization for face recognition is shared with mammals in distant taxa, suggesting that face recognition evolved earlier than the emergence of mammals. A recent study indicated that a social insect, the golden paper wasp, can distinguish their conspecific faces, whereas a closely related species, which has a less complex social lifestyle with just one queen ruling a nest of underlings, did not show strong face recognition for their conspecifics. Social complexity and the need to differentiate between one another likely led humans to evolve their face recognition abilities.

  3. A kinetic study of the electrochemical hydrogenation of ethylene

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, S. [Department of Chemical Engineering and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada); Gardner, C.L., E-mail: cgardner88@sympatico.c [Department of Chemical Engineering and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada)

    2010-02-01

    In this study, we have examined the kinetics of the electrochemical hydrogenation of ethylene in a PEM reactor. While in itself this reaction is of little industrial interest, this reaction can be looked upon as a model reaction for many of the important hydrogenation processes including the refining of heavy oils and the hydrogenation of vegetable oils. To study the electrochemical hydrogenation of ethylene, several experimental techniques have been used including polarization measurements, measurement of the composition of the exit gases and potential step, transient measurements. The results show that the hydrogenation reaction proceeds rapidly and essentially to completion. By fitting the experimental transient data to the results from a zero-dimensional mathematical model of the process, a set of kinetic parameters for the reactions has been obtained that give generally good agreement with the experimental results. It seems probable that similar experimental techniques could be used to study the electrochemical hydrogenation of other unsaturated organic molecules of more industrial significance.

  4. CAN WE CONFIDENTLY STUDY VO2 KINETICS IN YOUNG PEOPLE?

    Directory of Open Access Journals (Sweden)

    Samantha G. Fawkner

    2007-09-01

    Full Text Available The study of VO2 kinetics offers the potential to non-invasively examine the cardiorespiratory and metabolic response to dynamic exercise and limitations to every day physical activity. Its non-invasive nature makes it hugely attractive for use with young people, both healthy and those with disease, and yet the literature, whilst growing with respect to adults, remains confined to a cluster of studies with these special populations. It is most likely that this is partly due to the methodological difficulties involved in studying VO2 kinetics in young people which are not present, or present to a lesser degree, with adults. This article reviews these methodological issues, and explains the main procedures that might be used to overcome them

  5. Release kinetic study of RHPC coated aspirin microcapsules.

    Science.gov (United States)

    Pathak, Y V; Dorle, A K

    1990-01-01

    The present communication deals with the study of the effect of pH on the drug release characteristics and the drug release kinetic from the RHPC (Rosin Hard Paraffin Combination) coated aspirin microcapsules. For the purpose of the present study the aspirin microcapsules were prepared by pan coating method imparting 15 coats using 10 per cent RHPC solution in acetone. A standard coating procedure was used to coat the aspirin granules. Dissolution studies were carried out in media with different pH. To get a clear picture drug release studies were conducted in each media for 3 h. The results showed that the RHPC films were resistant to acidic pH releasing less than 5 per cent and 15 per cent drug in 3 h in pH 1.2 and 3.0 respectively. The T 50% in pH 5.0 media was 163 min. The drug was released very quickly in pH 7.2 and 8.0. The release kinetic study showed that the release followed the classical first order pattern though the coated microcapsules used to be intact during the dissolution process, in case of the acidic pH media. The release kinetic was changed when the pH of the dissolution media was 7.2 and above. It was found that during the dissolution process the granules undergo erosion and the release mechanism does not follow a single process.

  6. Inactivation disinfection property of Moringa Oleifera seed extract: optimization and kinetic studies

    Science.gov (United States)

    Idris, M. A.; Jami, M. S.; Hammed, A. M.

    2017-05-01

    This paper presents the statistical optimization study of disinfection inactivation parameters of defatted Moringa oleifera seed extract on Pseudomonas aeruginosa bacterial cells. Three level factorial design was used to estimate the optimum range and the kinetics of the inactivation process was also carried. The inactivation process involved comparing different disinfection models of Chicks-Watson, Collins-Selleck and Homs models. The results from analysis of variance (ANOVA) of the statistical optimization process revealed that only contact time was significant. The optimum disinfection range of the seed extract was 125 mg/L, 30 minutes and 120rpm agitation. At the optimum dose, the inactivation kinetics followed the Collin-Selleck model with coefficient of determination (R2) of 0.6320. This study is the first of its kind in determining the inactivation kinetics of pseudomonas aeruginosa using the defatted seed extract.

  7. Study on Kinetics for Desulfurization of Model Diesel

    Institute of Scientific and Technical Information of China (English)

    Qian Jianhua; Zhou Yuenan; Liu Lin; Wang Yue; Xing Jinjuan; Lü Hong

    2009-01-01

    In this study, by means of the experiments for desulfurization of model diesel through oxi-dative extraction, the changes associated with the rate of desulfurization of diesel and the mechanism for oxidation of sulfides in diesel were explored. Through studying the mechanism for oxidation of sulfides and the principle of solvent extraction, the kinetic equation of desulfurization via oxidative extraction were determined. By means of the evaluation of model parameters and curve fitting, the reaction order between organic sulfide and sulfone, the intrinsic oxidation rate constant of organic sulfide and sulfone, and the equilibrium constant between suifone in model diesel and extractive sol-vent were determined. The experimental values of the desulfurization rate and the theoretical values of the corresponding model equation had closely demonstrated that the desulfurization reaction rate had high accuracy. And the reaction kinetics could provide an important basis for diesel desulfurization process in the future.

  8. Kinetic simulation study of one dimensional collisional bounded plasma

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A self-consistent kinetic simulation study ofone dimensional collisional bounded plasma is presented.The formation of stable sheath potential is investigated.It is found that mass ratio of electron and ion not onlyaffects the level of sheath potential, but also affectsthe ion temperature of system. It is clarified that the effects of secondaryemission electron on both the total potential dropand the temperature are not important.

  9. Adsorption of Procion Red on Natural Bentonite : Kinetic Studies

    Directory of Open Access Journals (Sweden)

    Tarmizi Taher

    2016-12-01

    Full Text Available Abstract: Adsorption of procion red on natural bentonite was studied by kinetic study to know the reactivity of procion red. Kinetic adsorption was determined using batch adsorption system at various times in several concentrations of procion red. Time of adsorption was investigated at 5, 10, 20, 30, 45, 60, 90, and 120 minutes in 10, 25, 50, and 75 mg/L of procion red. The data was calculated using Langmuir-Hinshelwood kinetic equation. The diffusions process of procion red into bentonite at lower concentration was faster than at higher concentration in general with fit correlation between [(ln(Co/C/C] vs t/C from Langmuir-Hinshelwood data. The adsorption procion red on bentonite data at various times shows Langmuir monolayer adsorption process in the surface of bentonite. Keyword: adsorption, procion red, natural bentonite, kinetic Abstrak (Indonesian: Adsorpsi procion merah pada bentonit alam telah dipelajari melalui studi kinetik untuk mengetahui reaktivitas procion merah. Kinetika adsorpsi ditentukan menggunakan sistem adsorpsi simultan pada berbagai waktu dalam beberapa konsentrasi procion merah. Waktu adsorpsi dipelajari pada 5, 10, 20, 30, 45, 60, 90, dan 120 menit pada konsentrasi procion merah 10, 25, 50, dan 75 mg/L. Data dihitung menggunakan persamaan kinetika Langmuir-Hinshelwood. Proses difusi procion merah ke dalam bentonit pada konsentrasi rendah lebih cepat dibanding pada konsentrasi lebih tinggi secara umum dengan hubungan korelasi yang lurus antara [(ln(Co/C/C] versus t/C dari data Langmuir-Hinshelwood. Adsorpsi procion merah pada bentonit dengan berbagai variasi waktu adsorpsi menunjukkan proses adsorpsi satu lapisan pada permukaan bentonit. Katakunci: adsorpsi, procion merah, bentonit alam, kinetik

  10. Atorvastatin and Fenofibrate have Comparable Effects on VLDL-Apolipoprotein C-III Kinetics in Men with the Metabolic Syndrome

    Science.gov (United States)

    Chan, Dick C; Watts, Gerald F; Ooi, Esther M.M; Ji, Juying; Johnson, Anthony G; Barrett, P Hugh R

    2009-01-01

    Objectives The metabolic syndrome (MetS) is characterised by insulin resistance and dyslipidemia that may accelerate atherosclerosis. Disturbed apolipoprotein (apo) C-III metabolism may account for dyslipidemia in these subjects. Atorvastatin and fenofibrate decrease plasma apoC-III, but the underlying mechanisms are not fully understood. Methods and Results The effects of atorvastatin (40 mg/d) and fenofibrate (200mg/d) on the kinetics of very-low density lipoprotein (VLDL)-apoC-III were investigated in a cross-over trial of 11 MetS men. VLDL-apoC-III kinetics were studied, following intravenous d3-leucine administration using gas chromatography-mass spectrometry and compartmental modeling. Compared with placebo, both atorvastatin and fenofibrate significantly decreased (Ptriglyceride, apoB, apoB-48 and total apoC-III. Atorvastatin, not fenofibrate, significantly decreased plasma apoA-V concentrations (Pkinetics in MetS; reduced production and increased fractional catabolism of VLDL-apoC-III may explain the triglyceride-lowering effect of these agents. PMID:18566295

  11. Kinetic Study on Channelling of Protons in Metallic Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Dan; SONG Yuan-Hong; WANG You-Nian

    2008-01-01

    Based on the kinetic model and the dielectric response theory, a theoretical model is put forward to describe the transport of protons along nanotube axes. With the introduction of electron band structure for different nanotubes like zigzag and armchair nanotubes of metallic properties, the collective excitation of electrons on the cylinders induced by the incident ions is studied, showing several distinct peaks in the curves of the energy loss function. Furthermore, the stopping power and the self-energy are calculated as functions of ion velocities, especially taking into account the influence of damping coefficients. It is conceivable from the results that, in the kinetic formulation, plasmon excitation plays a major role in the stopping. And as the damping increases, the peaks of the stopping power shift to the lower velocities, with the broadening of the plasmon resonance.

  12. Kinetic Study on CO2 Reforming of Methane

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The kinetics of CO2 reforming of methane has been studied at 976-1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio > 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.

  13. Quantitative study of kinetic ballooning mode theory in simple geometry

    Science.gov (United States)

    Aleynikova, Ksenia; Zocco, Alessandro

    2017-09-01

    The theory of kinetic ballooning modes (KBMs) in a magnetically confined toroidal plasma is studied analytically and numerically by means of gyrokinetic simulations. A physics-based ordering for β (the ratio of kinetic to magnetic plasma pressure) with small asymptotic parameters is found. This allows us to derive several simplified limits of previously known theories. We introduce a variational approach which provides explicit dispersion relations in terms of integrals of quadratic forms constructed from numerical eigenfunctions. It is found that, for large pressure gradients, the growth rate and frequencies computed by gyrokinetic codes show excellent agreement with those evaluated by using a diamagnetic modification of ideal magnetohydrodynamic if geometric drifts are kept consistent with the equilibrium pressure gradient. For moderate pressure gradients, a new finite-β formulation of the KBM theory is proposed. Also in this case, a good agreement between numerical simulations and analytical theory is found.

  14. DEFLUORIDATION OF DRINKING WATER BY ELECTROCOAGULATION/ELECTROFLOTATION - KINETIC STUDY

    Directory of Open Access Journals (Sweden)

    Bennajah Mounir

    2010-06-01

    Full Text Available A variable order kinetic (VOK model derived from the langmuir-freundlish equation was applied to determine the kinetics of fluoride removal reaction by electrocoagulation (EC. Synthetic solutions were employed to elucidate the effects of the initial fluoride concentration, the applied current and the initial acidity on the simulation results of the model. The proposed model successfully describes the fluoride removal in Airlift reactor in comparison with the experimental results. In this study two EC cells with the same capacity (V = 20 L were used to carry out fluoride removal with aluminum electrodes, the first is a stirred tank reactor (STR the second is an airlift reactor (ALR. The comparison of energy consumption demonstrates that the (ALR is advantageous for carrying out the defluoridation removal process.

  15. DEFLUORIDATION OF DRINKING WATER BY ELECTROCOAGULATION/ELECTROFLOTATION: KINETIC STUDY

    Directory of Open Access Journals (Sweden)

    Mounir Bennajah

    2010-01-01

    Full Text Available A variable order kinetic (VOK model derived from the langmuir-freundlish equation was applied to determine the kinetics of fluoride removal reaction by electrocoagulation (EC. Synthetic solutions were employed to elucidate the effects of the initial fluoride concentration, the applied current and the initial acidity on the simulation results of the model. The proposed model successfully describes the fluoride removal in Airlift reactor in comparison with the experimental results. In this study two EC cells with the same capacity (V = 20 L were used to carry out fluoride removal with aluminum electrodes, the first is a stirred tank reactor (STR the second is an airlift reactor (ALR. The comparison of energy consumption demonstrates that the (ALR is advantageous for carrying out the defluoridation removal process.

  16. Kinetic study of ion-acoustic plasma vortices

    Energy Technology Data Exchange (ETDEWEB)

    Khan, S. A. [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad 45320 (Pakistan); Aman-ur-Rehman, E-mail: amansadiq@gmail.com [Pakistan Institute of Engineering and Applied Sciences (PIEAS), P.O. Nilore, Islamabad 45650 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Téchnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2014-09-15

    The kinetic theory of electron plasma waves with finite orbital angular momentum has recently been introduced by Mendonca. This model shows possibility of new kind of plasma waves and instabilities. We have extended the theory to ion-acoustic plasma vortices carrying orbital angular momentum. The dispersion equation is derived under paraxial approximation which exhibits a kind of linear vortices and their Landau damping. The numerical solutions are obtained and compared with analytical results which are in good agreement. The physical interpretation of the ion-acoustic plasma vortices and their Landau resonance conditions are given for typical case of Maxwellian plasmas.

  17. Kinetic study of ozonation of molasses fermentation wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Coca, M. [Departamento de Ingenieria Quimica y Tecnologia del Medio Ambiente, Universidad de Valladolid, Prado de la Magdalena s/n, 47011 Valladolid (Spain)], E-mail: monica@iq.uva.es; Pena, M.; Gonzalez, G. [Departamento de Ingenieria Quimica y Tecnologia del Medio Ambiente, Universidad de Valladolid, Prado de la Magdalena s/n, 47011 Valladolid (Spain)

    2007-10-22

    A kinetic study of molasses wastewater ozonation was carried out in a stirred tank reactor to obtain the rate constants for the decolorization reaction and the regime through which ozone is absorbed. First, fundamental mass transfer parameters such as ozone solubility, volumetric mass transfer coefficients and ozone decomposition kinetics were determined from semi-batch experiments in organic-free solutions with an ionic composition similar that of industrial wastewater. The influence of operating variables such as the stirring rate and gas flow rate on the kinetic and mass transfer parameters was also studied. The application of film theory allows to establish that the reactions between ozone and colored compounds in wastewater take place in the fast and pseudo-first-order regime, within the liquid film. The decolorization rate constants were evaluated at pH 8.7 and 25 deg. C, varying from 0.6 x 10{sup 7} to 3.8 x 10{sup 7} L mol{sup -1} s{sup -1}, depending on the stirring rate and the inlet gas flow.

  18. Kinetic study of biohydrogen production in mixed cultures

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.-H.; Khanal, S.K.; Sung, S. [Iowa State Univ., Ames, IA (United States). Dept. of Civil Construction and Environmental Engineering

    2004-07-01

    Hydrogen is considered to be a clean energy source and a promising alternative to fossil fuels. The production of biohydrogen from renewable feedstocks such as sugars and organic wastes has gained renewed interest in response to energy insecurity and environmental concerns. The main challenge of producing biohydrogen is the low hydrogen conversion efficiency in the dark fermentation process. A better reactor design could solve the problem. A good index for process design is the microbial growth rate during a growth phase, as this has a strong impact on culture productivity. Microbial growth rate is also a good index for maximizing biohydrogen production. Kinetic studies generally identify the significant operating parameters such as maximum specific growth rate and half-saturation constant. However, this traditional approach cannot be used for hydrogen producing systems. This study established an alternative method to determine growth kinetics for hydrogen producing bacteria. Sucrose and nonfat dairy milk were the substrates used to identify the growth kinetics in a series of batch experiments. The parameters can be used to design a continuous reactor system for an enriched culture of hydrogen producing bacteria. 1 fig.

  19. MCNP5 study on kinetics parameters of coupled fast-thermal system HERBE

    Directory of Open Access Journals (Sweden)

    Pešić Milan P.

    2011-01-01

    Full Text Available New validation of the well-known Monte Carlo code MCNP5 against measured criticality and kinetics data for the coupled fast-thermal HERBE System at the Reactor B critical assembly is shown in this paper. Results of earlier calculations of these criticality and kinetics parameters, done by combination of transport and diffusion codes using two-dimension geometry model are compared to results of new calculations carried out by the MCNP5 code in three-dimension geometry. Satisfactory agreements in comparison of new results with experimental data, in spite complex heterogeneous composition of the HERBE core, are achieved confirming that MCNP5 code could apply successfully to study on HERBE kinetics parameters after uncertainties in impurities in material compositions and positions of fuel elements in fast zone were removed.

  20. Comparative decomposition kinetics of neutral monosaccharides by microwave and induction heating treatments.

    Science.gov (United States)

    Tsubaki, Shuntaro; Oono, Kiriyo; Onda, Ayumu; Yanagisawa, Kazumichi; Azuma, Jun-ichi

    2013-06-28

    The stabilities of five neutral monosaccharides (glucose, galactose, mannose, arabinose, and xylose) were kinetically compared after the molecules were submitted to microwave heating (internal heating) and induction heating (external heating) under completely identical thermal histories by employing PID (proportional, integral, and derivative) temperature controlled ovens and homogeneous mixing. By heating in water at 200°C, the rate constants for the decomposition reactions varied from 2.13×10(-4) to 3.87×10(-4)s(-1) for microwave heating; however, the values increased by 1.1- to 1.5-fold for induction heating. Similarly, in a dilute (0.8%) sulfuric acid solution, the decomposition rate constants varied from 0.61×10(-3) to 2.00×10(-3)s(-1) for microwave heating; however, the values increased by 1.5- to 2.2-fold for induction heating. The results show that microwave heating imparts greater stability to neutral monosaccharides than does induction heating. The undesirable decomposition of monosaccharides at the surface boundary of reactor walls may have increased the probability of monosaccharide decomposition during induction heating.

  1. Comparative kinetics of Qi site inhibitors of cytochrome bc1 complex: picomolar antimycin and micromolar cyazofamid.

    Science.gov (United States)

    Li, Hui; Zhu, Xiao-Lei; Yang, Wen-Chao; Yang, Guang-Fu

    2014-01-01

    Antimycin and cyazofamid are specific inhibitors of the mitochondrial respiratory chain and bind to the Qi site of the cytochrome bc1 complex. With the aim to understand the detailed molecular inhibition mechanism of Qi inhibitors, we performed a comparative investigation of the inhibitory kinetics of them against the porcine bc1 complex. The results showed that antimycin is a slow tight-binding inhibitor of succinate-cytochrome c reductase (SCR) with Ki  = 0.033 ± 0.00027 nm and non-competitive inhibition with respect to cytochrome c. Cyazofamid is a classical inhibitor of SCR with Ki  = 12.90 ± 0.91 μm and a non-competitive inhibitor with respect to cytochrome c. Both of them show competitive inhibition with respect to substrate DBH2 . Further molecular docking and quantum mechanics calculations were performed. The results showed that antimycin underwent significant conformational change upon the binding. The energy barrier between the conformations in the crystal and in the binding pocket is ~13.63 kcal/mol. Antimycin formed an H-bond with Asp228 and two water-bridged H-bonds with Lys227 and His201, whereas cyazofamid formed only one H-bond with Asp228. The conformational change and the different hydrogen bonding network might account for why antimycin is a slow tight-binding inhibitor, whereas cyazofamid is a classic inhibitor.

  2. Antioxidant activity and kinetics studies of eugenol and 6-bromoeugenol.

    Science.gov (United States)

    Mahboub, Radia; Memmou, Faiza

    2015-01-01

    In this work, we report the antioxidant and free radical scavenging activity of 6-bromoeugenol and eugenol. EC50, the concentration providing 50% inhibition, is calculated and the antioxidant activity index (AAI) is evaluated. The antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging method. EC50 values of 6-bromoeugenol, ascorbic acid and eugenol were 34.270 μg/mL, 54.888 μg/mL and 130.485 μg/mL, respectively. 6-Bromoeugenol showed higher AAI value (1.122) followed by ascorbic acid (0.700), then by eugenol (0.295). We also investigate the kinetics of DPPH radical scavenging activity of our products to determine the useful parameter TEC50 to evaluate their antiradical efficiency (ARE). Our results have shown high ARE. This study has provided the following ARE ( × 10(-3)) order for the tested antioxidants: ascorbic acid (70.119)>6-bromoeugenol (34.842) > eugenol (21.313). Finally, we classify ascorbic acid and eugenol as fast kinetics reaction (TEC50 8.82 and 11.38 min, respectively) and 6-bromoeugenol as medium kinetics reaction (TEC50 39.24 min).

  3. Comparative in vitro fermentation activity in the canine distal gastrointestinal tract and fermentation kinetics of fiber sources.

    Science.gov (United States)

    Bosch, G; Pellikaan, W F; Rutten, P G P; van der Poel, A F B; Verstegen, M W A; Hendriks, W H

    2008-11-01

    The current study aimed to evaluate the variation in fermentation activity along the distal canine gastrointestinal tract (GIT, Exp. 1). It also aimed to assess fermentation kinetics and end product profiles of 16 dietary fibers for dog foods using canine fecal inoculum (Exp. 2). For Exp. 1, digesta were collected from the distal ileum, proximal colon, transverse colon, and rectum of 3 adult dogs. Digesta per part of the GIT were pooled for 3 dogs, diluted (1:25, wt/vol), mixed, and filtered for the preparation of inoculum. A fructan, ground soy hulls, and native potato starch were used as substrates and incubated for cumulative gas production measurement as an indicator of the kinetics of fermentation. In addition, fermentation bottles with similar contents were incubated but were allowed to release their gas throughout incubation. Fermentation fluid was sampled at 4, 8, 12, 24, 48, and 72 h after initiation of incubation, and short-chain fatty acids and ammonia were measured. Results showed comparable maximal fermentation rates for rectal and proximal colonic inocula (P > 0.05). Production of short-chain fatty acids was least for the ileal and greatest for the rectal inoculum (P fiber, peanut hulls, soy fiber, sugar beet fiber, sugar beet pectin, sugar beet pulp, wheat fiber, and wheat middlings. Feces of 4 adult dogs were used as an inoculum source. Similar techniques were used as in Exp. 1 except for the dilution factor used (1:10, wt/vol). Among substrates, large variations in fermentation kinetics and end product profiles were noted. Sugar beet pectin, the fructans, and the gums were rapidly fermentable, indicated by a greater maximal rate of gas production (R(max)) compared with all other substrates (P fiber were poorly fermentable, indicated by the least amount of gas produced (P fiber, sugar beet pulp, soy fiber, and wheat middlings were moderately fermentable with a low R(max). Citrus pectin and pea fiber showed a similar low R(max), but time at which

  4. A Study of the Optimal Model of the Flotation Kinetics of Copper Slag from Copper Mine BOR

    Science.gov (United States)

    Stanojlović, Rodoljub D.; Sokolović, Jovica M.

    2014-10-01

    In this study the effect of mixtures of copper slag and flotation tailings from copper mine Bor, Serbia on the flotation results of copper recovery and flotation kinetics parameters in a batch flotation cell has been investigated. By simultaneous adding old flotation tailings in the ball mill at the rate of 9%, it is possible to increase copper recovery for about 20%. These results are compared with obtained copper recovery of pure copper slag. The results of batch flotation test were fitted by MatLab software for modeling the first-order flotation kinetics in order to determine kinetics parameters and define an optimal model of the flotation kinetics. Six kinetic models are tested on the batch flotation copper recovery against flotation time. All models showed good correlation, however the modified Kelsall model provided the best fit.

  5. Biofuel: a comparative case study

    OpenAIRE

    Siddiqui, Aamir; Kading, Christopher; Carter, Kasey

    2013-01-01

    Approved for public release; distribution is unlimited This project analyzes the governments role in the commercialization of biofuel by comparing biofuel commercialization efforts to those of nuclear power and nanotechnology commercialization. The PESTEL framework is applied to nuclear power and nanotechnology to identify key factors relevant to successful commercialization. These success factors are compared to current government biofuel policies to infer the likelihood of successful bio...

  6. A comparative kinetic and thermodynamic perspective of the σ-competition model in Escherichia coli.

    Science.gov (United States)

    Ganguly, Abantika; Chatterji, Dipankar

    2012-09-19

    Transcription is the most fundamental step in gene expression in any living organism. Various environmental cues help in the maturation of core RNA polymerase (RNAP; α(2)ββ'ω) with different σ-factors, leading to the directed recruitment of RNAP to different promoter DNA sequences. Thus it is essential to determine the σ-factors that affect the preferential partitioning of core RNAP among various σ-actors, and the role of σ-switching in transcriptional gene regulation. Further, the macromolecular assembly of holo RNAP takes place in an extremely crowded environment within a cell, and thus far the kinetics and thermodynamics of this molecular recognition process have not been well addressed. In this study we used a site-directed bioaffinity immobilization method to evaluate the relative binding affinities of three different Escherichia coli σ-factors to the same core RNAP with variations in temperature and ionic strength while emulating the crowded cellular milieu. Our data indicate that the interaction of core RNAP-σ is susceptible to changes in external stimuli such as osmolytic and thermal stress, and the degree of susceptibility varies among different σ-factors. This allows for a reversible σ-switching from housekeeping factors to alternate σ-factors when the organism senses a change in its physiological conditions.

  7. The kinetics of uptake and recovery of lanthanum using freshwater algae as biosorbents: comparative analysis.

    Science.gov (United States)

    Birungi, Z S; Chirwa, E M N

    2014-05-01

    In this study, the adsorption and desorption kinetics of lanthanum (La) on micro algal cells was investigated. The internal transcribed spacer (ITS) and 18S ribosomal RNA gene (rRNA) were used for molecular identification of the species. The algal species were found to have 95-98% identities to Desmodesmus multivariabilis, Scenedesmus acuminutus, Chloroidium saccharophilum and Stichococcus bacillaris. The species were cultured and tested independently. D. multivariabilis was found to be the most efficient at adsorbing lanthanum with a maximum sorption capacity (qmax) of 100 mg/g and a high affinity (b) of 4.55 L/g. Desorption of La was also highest in D. multivariabilis with recovery up to 99.63% at initial concentration as high as 100 mg/L. Desorption data fitted best to the modified pseudo second-order with a better correlation coefficient (R(2)) of ⩽0.98 than first order model. The results showed feasibility of lanthanum recovery using algal sorbents, a cost effective method.

  8. ULF foreshock under radial IMF: THEMIS observations and global kinetic simulation Vlasiator results compared

    Science.gov (United States)

    Palmroth, Minna; Rami, Vainio; Archer, Martin; Hietala, Heli; Afanasiev, Alexandr; Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

    2015-04-01

    For decades, a certain type of ultra low frequency waves with a period of about 30 seconds have been observed in the Earth's quasi-parallel foreshock. These waves, with a wavelength of about an Earth radius, are compressive and propagate with an average angle of 20 degrees with respect of the interplanetary magnetic field (IMF). The latter property has caused trouble to scientists as the growth rate for the instability causing the waves is maximized along the magnetic field. So far, these waves have been characterized by single or multi-spacecraft methods and 2-dimensional hybrid-PIC simulations, which have not fully reproduced the wave properties. Vlasiator is a newly developed, global hybrid-Vlasov simulation, which solves the six-dimensional phase space utilising the Vlasov equation for protons, while electrons are a charge-neutralising fluid. The outcome of the simulation is a global reproduction of ion-scale physics in a holistic manner where the generation of physical features can be followed in time and their consequences can be quantitatively characterised. Vlasiator produces the ion distribution functions and the related kinetic physics in unprecedented detail, in the global scale magnetospheric scale with a resolution of a couple of hundred kilometres in the ordinary space and 20 km/s in the velocity space. We run Vlasiator under a radial IMF in five dimensions consisting of the three-dimensional velocity space embedded in the ecliptic plane. We observe the generation of the 30-second ULF waves, and characterize their evolution and physical properties in time. We compare the results both to THEMIS observations and to the quasi-linear theory. We find that Vlasiator reproduces the foreshock ULF waves in all reported observational aspects, i.e., they are of the observed size in wavelength and period, they are compressive and propagate obliquely to the IMF. In particular, we discuss the issues related to the long-standing question of oblique propagation.

  9. Atmospheric degradation of 3-methylfuran: kinetic and products study

    Directory of Open Access Journals (Sweden)

    A. Tapia

    2010-10-01

    Full Text Available A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases, using a relative method with different experimental techniques. The absolute rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1: kOH=(1.13±0.22×10−10 and kNO3=(1.26±0.18×10−11. These rate coefficients have been compared with those available in the literature. The products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NOx species have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones for the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones for the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds for the reaction with NO3 radicals. The results indicate that in all cases the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for both Cl atoms and the NO3 radical in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.

  10. Kinetic Monte Carlo studies of the reaction kinetics of crystal defects that diffuse one-dimensionally with occasional transverse migration

    DEFF Research Database (Denmark)

    Heinisch, H.L.; Trinkaus, H.; Singh, Bachu Narain

    2007-01-01

    and confirmed by kinetic Monte Carlo (KMC) simulations. Here we report on KMC simulations investigating a different transition from 1D to 3D diffusion of 1D gliding loops for which their 1D migration is interrupted by occasional 2D migration due to conservative climb by dislocation core diffusion within a plane...... transverse to their 1D glide direction. Their transition from 1D to 3D kinetics is significantly different from that due to direction changes. The KMC results are compared to an analytical description of this diffusion mode in the form of a master curve relating the 1D normalized sink strength...

  11. Kinetics of kill of bacterial conjunctivitis isolates with moxifloxacin, a fluoroquinolone, compared with the aminoglycosides tobramycin and gentamicin

    Directory of Open Access Journals (Sweden)

    Rudolph S Wagner

    2010-01-01

    Full Text Available Rudolph S Wagner1, David B Granet2, Steven J Lichtenstein3, Tiffany Jamison4, Joseph J Dajcs4, Robert D Gross5, Paul Cockrum41New Jersey Medical School, Newark, NJ, USA; 2Ratner Children’s Eye Center, University of California – San Diego, La Jolla, CA, USA; 3University of Illinois College of Medicine at Peoria, Peoria, Illinois, USA; 4Alcon Research, Ltd, Fort Worth, TX, USA; 5Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USAPurpose: To compare the kinetics and speed of kill of Streptococcus pneumoniae and Haemophilus influenzae on exposure to three topical ophthalmic antibiotic solutions.Materials and methods: Bacterial conjunctivitis isolates of S. pneumoniae and H. influenzae were exposed to 1:1000 dilutions of moxifloxacin 0.5%, tobramycin 0.3%, gentamicin 0.3%, and water (control. At 15, 30, 60, 120, and 180 minutes after exposure, aliquots were collected, cells were cultured, and viable cell counts were determined using standard microbiological methods.Results: Moxifloxacin achieved 99.9% kill (3-log reduction at approximately 2 hours for S. pneumoniae and at 15 minutes for H. influenzae. Tobramycin and gentamicin did not achieve 3-log reduction of S. pneumoniae during the 180-minute study period. An increase in bacterial growth was noted for these isolates. Gentamicin took more than 120 minutes to achieve the 3-log reduction of H. influenzae and tobramycin did not reach the 3-log reduction of this pathogen during the 180-minute study period.Conclusion: Moxifloxacin killed S. pneumoniae and H. influenzae in vitro faster than tobramycin and gentamicin, suggesting its potential clinical benefit as a first-line treatment for bacterial conjunctivitis to minimize patient symptoms and to limit the contagiousness of the disease.Keywords: kinetics of kill, bacterial conjunctivitis, in vitro, Streptococcus pneumoniae, Haemophilus influenzae, fluoroquinolones, aminoglycosides

  12. Kinetics study on biomass pyrolysis for fuel gas production

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The kinetic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into primary products (tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme.

  13. Kinetics study on biomass pyrolysis for fuel gas production

    Institute of Scientific and Technical Information of China (English)

    陈冠益; 方梦祥; ANDRIES,J.; 骆仲泱; SPLIETHOFF,H.; 岑可法

    2003-01-01

    Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The ki-netic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into pri-mary products ( tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme.

  14. Adsorption of dyes using peat: equilibrium and kinetic studies.

    Science.gov (United States)

    Sepúlveda, L; Fernández, K; Contreras, E; Palma, C

    2004-09-01

    In recent years, adsorption has been accepted as one of the most appropriate processes for decolorization of wastewaters. This paper presents experimental results on application of peat for removal of structurally diverse dyes (azo, oxazine, triphenylmethane, thiazine and others) with emphasis on relevant factors such as the adsorbate-adsorbent chemical properties and chemical interaction as well as adsorption conditions. The equilibrium experimental results were fitted to Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model. According to the evaluation using the Langmuir equation, the maximum sorption capacity of basic dyes at 22 degrees C was 667 (mg g(-1)) for Basic Blue 24, 526 (mg g(-1)) for Basic Green 4 and 714 (mg g(-1)) for Basic Violet 4. On the other hand for Acid Black 1 it was only 25 (mg g(-1)). Batch kinetics studies were undertaken and the data evaluated in compliance with chemical sorption mechanisms. For all of the systems studied the pseudo-second order model provided the best correlation of the kinetic experimental data. A film-pore double resistance diffusion model for mass transfer has also been used in this study to determine the effective diffusivity, Deff, for the adsorption of basic dyes in to peat.

  15. Isotherm, kinetic, and thermodynamic study of ciprofloxacin sorption on sediments.

    Science.gov (United States)

    Mutavdžić Pavlović, Dragana; Ćurković, Lidija; Grčić, Ivana; Šimić, Iva; Župan, Josip

    2017-04-01

    In this study, equilibrium isotherms, kinetics and thermodynamics of ciprofloxacin on seven sediments in a batch sorption process were examined. The effects of contact time, initial ciprofloxacin concentration, temperature and ionic strength on the sorption process were studied. The K d parameter from linear sorption model was determined by linear regression analysis, while the Freundlich and Dubinin-Radushkevich (D-R) sorption models were applied to describe the equilibrium isotherms by linear and nonlinear methods. The estimated K d values varied from 171 to 37,347 mL/g. The obtained values of E (free energy estimated from D-R isotherm model) were between 3.51 and 8.64 kJ/mol, which indicated a physical nature of ciprofloxacin sorption on studied sediments. According to obtained n values as measure of intensity of sorption estimate from Freundlich isotherm model (from 0.69 to 1.442), ciprofloxacin sorption on sediments can be categorized from poor to moderately difficult sorption characteristics. Kinetics data were best fitted by the pseudo-second-order model (R (2) > 0.999). Thermodynamic parameters including the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were calculated to estimate the nature of ciprofloxacin sorption. Results suggested that sorption on sediments was a spontaneous exothermic process.

  16. An experimental and kinetic modeling study of combustion of isomers of butanol

    Energy Technology Data Exchange (ETDEWEB)

    Grana, Roberto; Frassoldati, Alessio; Faravelli, Tiziano; Ranzi, Eliseo [Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Milano (Italy); Niemann, Ulrich; Seiser, Reinhard; Cattolica, Robert; Seshadri, Kalyanasundaram [Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, CA 92093-0411 (United States)

    2010-11-15

    A kinetic model is developed to describe combustion of isomers of butanol - n-butanol (n-C{sub 4}H{sub 9}OH), sec-butanol (sec-C{sub 4}H{sub 9}OH), iso-butanol (iso-C{sub 4}H{sub 9}OH), and tert-butanol (tert-C{sub 4}H{sub 9}OH). A hierarchical approach is employed here. This approach was previously found to be useful for developing detailed and semi-detailed mechanism of oxidation of various hydrocarbon fuels. This method starts from lower molecular weight compounds of a family of species and proceeds to higher molecular weight compounds. The pyrolysis and oxidation mechanisms of butanol isomers are similar to those for hydrocarbon fuels. Here, the development of the complete set of the primary propagation reactions for butanol isomers proceeds from the extension of the kinetic parameters for similar reactions already studied and recently revised for ethanol, n-propanol and iso-propanol. A detailed description leading to evaluation of rate constants for initiation reactions, metathesis reactions, decomposition reactions of alkoxy radicals, isomerization reactions, and four-center molecular dehydration reactions are given. Decomposition and oxidation of primary intermediate products are described using a previously developed semi-detailed kinetic model for hydrocarbon fuels. The kinetic mechanism is made up of more than 7000 reactions among 300 species. The model is validated by comparing predictions made using this kinetic model with previous and new experimental data on counterflow non-premixed flames of n-butanol and iso-butanol. The structures of these flames were measured by removing gas samples from the flame and analyzing them using a gas chromatograph. Temperature profiles were measured using coated thermocouples. The flame structures were measured under similar conditions for both fuels to elucidate the similarities and differences in combustion characteristics of the two isomers. The profiles measured include those of butanol, oxygen, carbon dioxide

  17. Chemical kinetics on thermal decompositions of cumene hydroperoxide in cumene studied by calorimetry: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Duh, Yih-Shing, E-mail: yihshingduh@yahoo.com.tw [Department of Occupation Safety and Health, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, 35664, Taiwan, ROC (China); Department of Safety, Health and Environmental Engineering, National United University, No. 1 Lien-Da, Miaoli, 36052, Taiwan, ROC (China)

    2016-08-10

    Highlights: • Chemical kinetics on thermal decompositions of CHP are conducted and summarized. • Kinetics agrees well between data from DSC and adiabatic calorimetry. • Ea is determined to be about 120 kJ mol{sup −1} by various calorimetry. • LogA (A in s{sup −1}) is determined to be about 11.8 by various calorimetry. - Abstract: Study on chemical kinetics related to the thermal decomposition of cumene hydoperoxide (CHP) in cumene is summarized in this work. It is of great importance to gather and compare the differences between these kinetic parameters for further substantial applications in the chemical industry and process safety. CHP has been verified to possess an autocatalytic behavior by using microcalorimetry (such as TAM and C-80) operated at isothermal mode in the temperature range from 70 °C to 120 °C. However, it exhibits a reaction of n-th order detected by non-isothermal DSC scanning and adiabatic calorimeter. By the isothermal aging tests, activation energy and frequency factor in logA(s{sup −1}) were averaged to be (117.3 ± 5.9) kJ mol{sup −1}and (11.4 ± 0.3), respectively. Kinetic parameters acquired from data of interlaboratories by using heat-flow calorimetry, the averaged activation energy and frequency factor in logA(s{sup −1}) were (119.3 ± 11.3) kJ mol{sup −1}and (12.0 ± 0.2), respectively. On the analogy of results from adiabatic calorimetry, the activation energy and frequency factor in logA(s{sup −1}) were respectively averaged to be (122.4 ± 9.2) kJ mol{sup −1}and (11.8 ± 0.8). Five sets of kinetic models in relation to autocatalytic reactions are collected and discussed as well.

  18. Kinetic Study of the Austempering Reactions in Ductile Irons

    Science.gov (United States)

    Pérez, M. J.; Cisneros, M. M.; Almanza, E.; Haro, S.

    2012-11-01

    Kinetics of the reaction that occur during the austempering heat treatment in unalloyed and alloyed ductile irons with 1Cu-0.25Mo, 1Ni-0.25Mo, and 0.7Cu-1Ni-0.25Mo, was studied. The austenitization and austempering cycles were achieved by isothermal dilatometry in cylindrical samples of 2 mm in diameter and 12 mm in length. The specimens were austenitized at 870 °C for 120 min, followed by isothermal holding for 300 min at temperatures between 270 and 420 °C. Kinetic parameters such as the order of reaction " n" and the rate of reaction " k" were calculated using the Johnson-Mehl equation while the empirical activation energy was calculated by means of the Arrhenius equation. It was found that the values of " k" decreased with the addition of Cu, Ni, and Mo as well as with the reduction of the isothermal temperature. The activation energy changes with the austempering temperature, in the range 30,348-58,250 J/mol when the heat treatment was carried out between 370 and 420 °C and 10,336-26,683 J/mol when the temperature varied from 270 to 350 °C. The microstructures in samples austempered at 370 and 315 °C were observed by transmission electron microscopy. No carbides precipitation was observed on samples heat treated at 370 °C for less than 120 min, while at 315 °C carbides of hexagonal structure ɛ(Fe2.4C) were found from the beginning of the transformation. The smallest value of activation energy and a slower kinetic transformation seem to be related with the presence of a carbide phase. Additionally, the time results obtained for transformation fractions of 0.05 and 0.95 by the dilatometry analysis were used to build the temperature-time-transformation diagrams for the irons.

  19. Large-scale epitaxial growth kinetics of graphene: A kinetic Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Huijun; Hou, Zhonghuai, E-mail: hzhlj@ustc.edu.cn [Department of Chemical Physics and Hefei National Laboratory for Physical Sciences at Microscales, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2015-08-28

    Epitaxial growth via chemical vapor deposition is considered to be the most promising way towards synthesizing large area graphene with high quality. However, it remains a big theoretical challenge to reveal growth kinetics with atomically energetic and large-scale spatial information included. Here, we propose a minimal kinetic Monte Carlo model to address such an issue on an active catalyst surface with graphene/substrate lattice mismatch, which facilitates us to perform large scale simulations of the growth kinetics over two dimensional surface with growth fronts of complex shapes. A geometry-determined large-scale growth mechanism is revealed, where the rate-dominating event is found to be C{sub 1}-attachment for concave growth-front segments and C{sub 5}-attachment for others. This growth mechanism leads to an interesting time-resolved growth behavior which is well consistent with that observed in a recent scanning tunneling microscopy experiment.

  20. Kinetic Study of Free Radicals Scavenging by Saffron Petal Extracts

    Directory of Open Access Journals (Sweden)

    T. Ardalan

    2013-01-01

    Full Text Available Saffron petal is the main by-product of saffron processing which is produced in large amounts, annually. The objectives of this study were to study the antioxidant activity and free radical-scavenging effects of saffron petal extracts. The ability of saffron petal to act as an antioxidant using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH free-radical method was investigated by applying the Uv–Vis spectrometry. The Uv–Vis spectra of reaction mixtures in acetonitrile revealed that saffron petal has a considerable effect on scavenging free radical. Kinetic studies were conducted by measuring the disappearance of DPPH in acetonitrile over the wavelength range of 515-522 nm under pseudo-first-order conditions at 37oC. Furthermore, the pseudo first order rate constants were determined

  1. Kinetic Batch Soil Adsorption Studies of 2, 4-dinitroanisole (DNAN)

    Science.gov (United States)

    Arthur, J.; Mark, N. W.; Taylor, S.; Brusseau, M. L.; Dontsova, K.

    2014-12-01

    Currently the explosive 2, 4, 6- trinitrotoluene (TNT) is used as a main ingredient in munitions; however the compound has failed to meet sensitivity requirements. The replacement compound being tested is 2, 4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bioavailability and exposure potential. DNAN has been shown to have some human and environmental toxicity. The objective of this study was to investigate the environmental fate of DNAN in soil, with a specific focus on sorption processes. Batch experiments were conducted using 11 soils collected from military installations located across the United States. The soils were characterized for pH, specific surface area, electrical conductivity, cation exchange capacity, and organic carbon content. Adsorption kinetic data determined at room temperature were fitted using the first order kinetic equation. Adsorption isotherms were fitted with linear and Freundlich isotherm equations. The magnitudes of the linear adsorption coefficients ranged from 0.6 to 6 cm3/g. Results indicated that the adsorption of DNAN is strongly dependent on the amount of organic carbon present in the soil.

  2. Pyrolysis of microalgae residues--A kinetic study.

    Science.gov (United States)

    Bui, Hau-Huu; Tran, Khanh-Quang; Chen, Wei-Hsin

    2016-01-01

    Pyrolysis of residues from the oil extraction process of two types of microalgae, Chlamydomonas (C. sp. JSC4) and Chlorella sorokiniana (C. Sorokiniana CY1) was studied by means of a thermogravimetric analyzer. Five pseudo-components (hemicellulose, cellulose, lignin, lipid and protein) model with n=1 or n#1 was assumed for a kinetic analysis of the collected pyrolysis data. The model with n#1 resulted in a slightly better fit quality and reasonable kinetic parameters. The calculated activation energy of hemicellulose, cellulose, lignin, lipid, protein was 115.12-117.12 kJ/mol, 181.67-198.30 kJ/mol, 61.74-62.75 kJ/mol, 104.93-114.14 kJ/mol and 90.75-99.31 kJ/mol, respectively, for C. sp. JSC4; and 113.12-117.12 kJ/mol, 218.73-28.79 kJ/mol, 64.77-66.39 kJ/mol, 131.97-143.63 kJ/mol and 108.03-118.13 kJ/mol, respectively, for C. Sorokiniana CY1. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Slag founding: kinetic study and election of a grinding system

    Directory of Open Access Journals (Sweden)

    Salas Vinent, M. E.

    2001-06-01

    Full Text Available Here we offer results obtained in laboratories and industry, concerning the kinetic study of steelfounding in cement manufacture. We choose the most suitable grinding system, valuing also its economical and environmental repercussion. The obtained results indicated that the kinetic method is extremely useful to solve the practical problems in the conception and design of grinding systems, and it is also a speed and the inverted bolting-rell gap almost like a Arrhenius equation.

    Se presentan resultados logrados a escala de laboratorio e industrial referidos al estudio cinético de las escorias de fundición de aceros para la producción de cementos. Se realiza la elección del sistema de molienda más adecuado, valorando además el efecto económico y medio ambiental del mismo. De los resultados obtenidos se concluye que el método cinético resulta de extrema utilidad en la solución de problemas prácticos para la concepción y diseño de sistemas de molienda, amén de que en el plano teórico resulta una novedad la correlación encontrada entre la constante de velocidad de molienda y el inverso de la abertura del tamiz de modo similar a la ecuación de Arrhenius.

  4. Kinetic Study of [2]Pseudorotaxane Formation with an Asymmetrical Thread.

    Science.gov (United States)

    Quiroga, Miguel; Parajó, Mercedes; Rodríguez-Dafonte, Pedro; García-Río, Luis

    2016-06-28

    Kinetic and thermodynamic studies on cyclodextrin (CD)-based [2]pseudorotaxane formation have been carried out by a combination of NMR and calorimetric techniques using bolaform surfactants as axles. Experimental evidence of the formation of an external complex between the trimethylammonium head groups of the axle and the external hydrogen atoms of α-cyclodextrin (α-CD) is reported. Inclusion of this external complex in the reaction pathway allows us to explain the kinetic behavior as well as the nonlinear dependence of the observed rate constant on CD concentrations. The equilibrium constant for [2]pseudorotaxane formation is strongly affected by the spacer length of the axle. This effect is a consequence of increasing rotaxane stability because the threading rate constant is almost independent of the spacer length, but dethreading strongly decreases on increasing the axle size. Using a nonsymmetrical axle with tripropyl and trimethylammonium cations precludes CD threading by the large head side. CDs will thread this asymmetrical bolaform by both their wide and narrow sides, yielding two isomeric [2]pseudorotaxanes. Threading by the wide side of the CD is 60% more favorable than that by the narrow one, but dethreading rate constants are the same for both isomers.

  5. Benchmarked Library Websites Comparative Study

    KAUST Repository

    Ramli, Rindra M.

    2015-01-01

    This presentation provides an analysis of services provided by the benchmarked library websites. The exploratory study includes comparison of these websites against a list of criterion and presents a list of services that are most commonly deployed by the selected websites. In addition to that, the investigators proposed a list of services that could be provided via the KAUST library website.

  6. Thermogravimetric analysis and kinetic study on pyrolysis of representative medical waste composition.

    Science.gov (United States)

    Deng, Na; Zhang, Yu-feng; Wang, Yan

    2008-01-01

    To obtain detailed information on the pyrolysis characteristics, a thermogravimetric study on the pyrolysis of 14 typical medical waste compositions was carried out in thermogravimetric analysis (TGA) equipment using dynamic techniques in a stream of N2. An index representing pyrolysis reactivity of waste was presented. Kinetic parameters were obtained by Coats-Redfern method and used to model the TG curve. The results showed that: (a) Plastic, protein, cellulosic material, synthetic fibre, and rubber entered pyrolysis process in succession. (b) There was one decomposition stage in the pyrolysis of one-off medical glove, operating glove, cellulosic waste, absorbable catgut suture and adhesive plaster, while other components had two obvious weight loss stages. (c) The obtained apparent activation energy for second stage pyrolysis was comparably higher than that for first stage. (d) Each stage was controlled by only one kinetic mechanism, in which kinetic parameters were constant. (e) The degradation kinetics of medical waste may be affected by special physical and chemical treatment in the product manufacturing process. (f) Among 13 waste samples, the pyrolysis index of cellulosic matter was the highest, which indicated cellulosic matter had strong pyrolysis reactivity. (g) With increasing heating rate, TG curve and DTG peak shifted to high temperatures and main reaction interval of the sample became longer.

  7. [Efficient method of analysis of optical spectra from kinetic studies].

    Science.gov (United States)

    Skvortsov, A N

    2009-01-01

    The application of principal components for the analysis of kinetic data obtained by optical spectroscopy is described. The use of singular value decomposition (SVD) for stable and reproducible generation of principal components, details of realization, advantages and drawbacks of the method are discussed. The described method with minor modifications may be used in a wide variety of UV-spectroscopy applications in molecular biology and biophysics. The developed method was applied to study the reaction of platinum anticancer drug, cisplatin, with DNA and methionine. Use of sensitive UV-spectroscopy allowed to study low platinum concentrations, typical for biological systems. It has been shown, that reactions of cisplatin with DNA and L-methionine generally follow the same pathway both at high and low concentrations.

  8. Kinetic study of hydrolysis of coconut fiber into glucose

    Science.gov (United States)

    Muhaimin, Sudiono, Sri

    2017-03-01

    Kinetic study of hydrolysis of coconut fiber into glucose has been done. The aim of this research was to study of the effect of time and temperature to the glucose as the result of the conversion of coconut fiber. The various temperature of the hydrolysis process were 30 °C, 48 °C, 72 °C and 95 °C and the various time of the hydrolysis process were 0, 15, 30, 60, 120, 180, 240, 300 minutes. A quantitative analysis was done by measured the concentration of the glucose as the result of the conversion of coconut fiber. The result showed that the rate constant from the various temperature were 3.10-4 minute-1; 8.10-4 minutees-1; 84.10-4 minute-1, and 205.10-4 minute-1, and the energy activation was 7,69. 103 kJ/mol.

  9. Kinetic Study of the Combustion of Phosphorus Containing Species

    Energy Technology Data Exchange (ETDEWEB)

    Glaude, P.A.; Curran, H.J.; Pitz, W.J.; Westbrook, C.K.

    1999-10-22

    The combustion of organophosphorus compounds is of great interest for the incineration of chemical warfare agent and their use in flame inhibition as halon replacement. The thermochemical data of these species and the reactions involved at high temperature are not well known, despite some recent experimental studies. With BAC-MP4 ab initio estimations as a basis and semi-empirical estimations for many new compounds, the thermochemistry of organophosphorus compounds is studied. New group additivity values are proposed for enthalpies of formation at 298K, entropies and heat capacities of species involving pentavalent phosphorus bonded to carbon, hydrogen, oxygen, fluorine, nitrogen and sulfur atoms. The kinetic of unimolecular elimination is investigated by modeling pyrolysis experiments of DEMP, TEP and DIMP. A new combustion mechanism is described and applied to the modeling of DMMP reaction in a H{sub 2}/O{sub 2} flame.

  10. Kinetic study for aerobic treatment of phenolic wastewater

    Directory of Open Access Journals (Sweden)

    Athar Hussain

    2015-09-01

    Full Text Available Conventional physico-chemical treatment of industrial wastewater containing compounds such as phenol encounters difficulties due to low substrate level, additional use of chemicals, and generation of hazardous by products along with increased process cost. Biological treatment appears to be a solution for treatment of such industrial wastewater. In the present study an aerobic sequential batch reactor (SBR has been used for treatment of synthetic wastewater containing phenol. The effects of increasing phenol concentrations on the sludge characteristic have been also investigated. It was observed that, activity of activated sludge for acclimatization of phenol decreases at concentrations above 2000 mg L−1. It may be attributed to toxicity of phenol to active biomass at higher concentrations. Kinetics of phenol degradation has also been studied using Haldane model.

  11. Accelerating finite-rate chemical kinetics with coprocessors: comparing vectorization methods on GPUs, MICs, and CPUs

    CERN Document Server

    Stone, Christopher P

    2016-01-01

    Efficient ordinary differential equation solvers for chemical kinetics must take into account the available thread and instruction-level parallelism of the underlying hardware, especially on many-core coprocessors, as well as the numerical efficiency. A stiff Rosenbrock and nonstiff Runge-Kutta solver are implemented using the single instruction, multiple thread (SIMT) and single instruction, multiple data (SIMD) paradigms with OpenCL. The performances of these parallel implementations were measured with three chemical kinetic models across several multicore and many-core platforms. Two runtime benchmarks were conducted to clearly determine any performance advantage offered by either method: evaluating the right-hand-side source terms in parallel, and integrating a series of constant-pressure homogeneous reactors using the Rosenbrock and Runge-Kutta solvers. The right-hand-side evaluations with SIMD parallelism on the host multicore Xeon CPU and many-core Xeon Phi co-processor performed approximately three ti...

  12. Physiologically based kinetic modeling of bioactivation and detoxification of the alkenylbenzene methyleugenol in human as compared with rat

    NARCIS (Netherlands)

    Al-Subeihi, A.A.; Spenkelink, A.; Punt, A.; Boersma, M.G.; Bladeren, van P.J.; Rietjens, I.

    2012-01-01

    This study defines a physiologically based kinetic (PBK) model for methyleugenol (ME) in human based on in vitro and in silico derived parameters. With the model obtained, bioactivation and detoxification of methyleugenol (ME) at different doses levels could be investigated. The outcomes of the curr

  13. Comparative in vitro fermentation activity in the canine distal gastrointestinal tract and fermentation kinetics of fiber sources

    NARCIS (Netherlands)

    Bosch, G.; Pellikaan, W.F.; Rutten, P.G.P.; Poel, van der A.F.B.; Verstegen, M.W.A.; Hendriks, W.H.

    2008-01-01

    The current study aimed to evaluate the variation in fermentation activity along the distal canine gastrointestinal tract (GIT, Exp. 1). It also aimed to assess fermentation kinetics and end product profiles of 16 dietary fibers for dog foods using canine fecal inoculum (Exp. 2). For Exp. 1, digesta

  14. Comparative in vitro fermentation activity in the canine distal gastrointestinal tract and fermentation kinetics of fiber sources

    NARCIS (Netherlands)

    Bosch, G.; Pellikaan, W.F.; Rutten, P.G.P.; Poel, van der A.F.B.; Verstegen, M.W.A.; Hendriks, W.H.

    2008-01-01

    The current study aimed to evaluate the variation in fermentation activity along the distal canine gastrointestinal tract (GIT, Exp. 1). It also aimed to assess fermentation kinetics and end product profiles of 16 dietary fibers for dog foods using canine fecal inoculum (Exp. 2). For Exp. 1, digesta

  15. Study of kinetics of the tetroxane thermolysis by UV spectrophotometry

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, N.L.; Leiva, L.C.; Castellanos, M.G.; Cafferata, L.F.R.; Gomez V, M.E. [Area de Quimica Fisica, Facultad de Ciencias Exactas y Naturales y de Agrimensura, U.N.N.E. Av. Libertad 5400, (3400) Corrientes, Republica Argentina (Argentina)

    2002-07-01

    The 3,3,6,6-tetramethyl-1,2,4,5-tetroxane (ACDP) in methanol solution shows an absorbance peak at low wave length in UV spectrum and follows the Lambert Beer law until 10-2 M concentration at 209 nm. The ACDP thermal decomposition have been studied by the UV spectroscopy like an alternative method to find out the kinetic parameters from the thermolysis of these compounds. The rate constants at the temperatures and initial concentration ranges of 130-166 and 0,003-0,013 mol / L, respectively, and the activation parameters were similar to the corresponding values found by other methodology, verifying this analytic technique. Acetone produced during reaction no interference in ACDP quantification by UV analysis. (Author)

  16. Carbohydrate deficient transferrin (CDT) in alcoholic cirrhosis: a kinetic study

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Grønbaek, M; Møller, Søren

    1997-01-01

    concentration than controls with a low alcohol intake (detected between carbohydrate deficient transferrin in artery and liver vein or artery and renal vein, either in patients with alcoholic cirrhosis (n = 11) or in controls (n = 8......BACKGROUND/AIMS: Carbohydrate deficient transferrin has been introduced as a marker of excessive alcohol intake. The present study was undertaken in order to measure the circulating level of carbohydrate deficient transferrin in patients with alcoholic cirrhosis and to assess arteriovenous kinetics...... of carbohydrate deficient transferrin in liver and kidney. METHODS/RESULTS: The median value of serum carbohydrate deficient transferrin was 16.0 U/l in patients with alcoholic cirrhosis (n = 41), and this value was not significantly different from that of a normal control group (median 17.4 U/l, n = 55, ns...

  17. An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

    2010-02-19

    Biodiesel is typically a mixture of long chain fatty acid methyl esters for use in compression ignition engines. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This research study presents new combustion data for methyl decanoate in an opposed-flow diffusion flame. An improved detailed chemical kinetic model for methyl decanoate combustion is developed, which serves as the basis for deriving a skeletal mechanism via the direct relation graph method. The novel skeletal mechanism consists of 648 species and 2998 reactions. This mechanism well predicts the methyl decanoate opposed-flow diffusion flame data. The results from the flame simulations indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

  18. Thermogravimetric kinetic study of agricultural residue biomass pyrolysis based on combined kinetics.

    Science.gov (United States)

    Wang, Xun; Hu, Mian; Hu, Wanyong; Chen, Zhihua; Liu, Shiming; Hu, Zhiquan; Xiao, Bo

    2016-11-01

    Pyrolytic kinetic of an agricultural residue (AR) feedstock, a mixture of plants (cotton, wheat, rich, corn) stems, was investigated based on combined kinetics. The most suitable mechanism for AR one-step pyrolysis was f(α)=(1-α)(1.1816)α(-1.8428) with kinetic parameters of: apparent activation energy 221.7kJ/mol, pre-exponential factor 4.17E16s(-1). Pyrolysis of AR feedstock could not be described by one-step reaction attributes to heterogeneous features of pyrolysis processes. Combined kinetics three-parallel-reaction (CK-TPR) model fitted the pyrolysis experimental data very well. Reaction mechanisms for pseudo hemicelluloses, cellulose, lignin in CK-TPR model was f(α)=(1-α)(1.6244)α(-0.3371)[-ln(1-α)](-0.0515), f(α)=(1-α)(1.0597)α(-0.6909)[-ln(1-α)](0.9026) and f(α)=(1-α)(2.9577)α(-4.7719), respectively. Apparent activation energy of three pseudo components followed the order of Elignin(197.3kJ/mol)>Ecellulose(176.3kJ/mol)>Ehemicelluloses (151.1kJ/mol). Mechanism of hemicelluloses pyrolysis could be further expressed as f(α)=(1-α)(1.4). The pyrolytic mechanism of cellulose met the Nucleation well. However, mechanism of lignin pyrolysis was complex, which possibly was the combined effects of Nucleation, Diffusion, Geometrical contraction, and Power law. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Preliminary study on mechanics-based rainfall kinetic energy

    Directory of Open Access Journals (Sweden)

    Yuan Jiuqin Ms.

    2014-09-01

    Full Text Available A raindrop impact power observation system was employed to observe the real-time raindrop impact power during a rainfall event and to analyze the corresponding rainfall characteristics. The experiments were conducted at different simulated rainfall intensities. As rainfall intensity increased, the observed impact power increased linearly indicating the power observation system would be satisfactory for characterizing rainfall erosivity. Momentum is the product of mass and velocity (Momentum=MV, which is related to the observed impact power value. Since there is no significant difference between momentum and impact power, observed impact power can represent momentum for different rainfall intensities. The relationship between momentum and the observed impact power provides a convenient way to calculate rainfall kinetic energy. The value of rainfall kinetic energy based on the observed impact power was higher than the classic rainfall kinetic energy. The rainfall impact power based kinetic energy and the classic rainfall kinetic energy showed linear correlation, which indicates that the raindrop impact power observation system can characterize rainfall kinetic energy. The article establishes a preliminary way to calculate rainfall kinetic energy by using the real-time observed momentum, providing a foundation for replacing the traditional methods for estimating kinetic energy of rainstorms.

  20. The kinetic study of oxidation of iodine by hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Cantrel, L. [Institut de Protection et de Surete Nucleaire, IPNS, CEN Cadarache, Saint Paul lez Durance (France); Chopin, J. [Laboratoire d`Electrochimie Inorganique, ENSSPICAM, Marseille (France)

    1996-12-01

    Iodine chemistry is one of the most important subjects of research in the field of reactor safety because this element can form volatile species which represent a biological hazard for environment. As the iodine and the peroxide are both present in the sump of the containment in the event of a severe accident on a light water nuclear reactor, it can be important to improve the knowledge on the reaction of oxidation of iodine by hydrogen peroxide. The kinetics of iodine by hydrogen peroxide has been studied in acid solution using two different analytical methods. The first is a UV/Vis spectrophotometer which records the transmitted intensity at 460 nm as a function of time to follow the decrease of iodine concentration, the second is an amperometric method which permits to record the increase of iodine+1 with time thanks to the current of reduction of iodine+1 to molecular iodine. The iodine was generated by Dushman reaction and the series of investigations were made at 40{sup o}C in a continuous stirring tank reactor. The influence of the initial concentrations of iodine, iodate, hydrogen peroxide, H{sup +} ions has been determined. The kinetics curves comprise two distinct chemical phases both for molecular iodine and for iodine+1. The relative importance of the two processes is connected to the initial concentrations of [I{sub 2}], [IO{sub 3}{sup -}], [H{sub 2}O{sub 2}] and [H{sup +}]. A rate law has been determined for the two steps for molecular iodine. (author) figs., tabs., 22 refs.

  1. Very rapid virologic response and early HCV response kinetics, as quick measures to compare efficacy and guide a personalized response-guided therapy

    Science.gov (United States)

    Yakoot, Mostafa; Abdo, Alaa M; Yousry, Ahmed; Helmy, Sherine

    2016-01-01

    Background This is the second and final report for our study designed to compare two generic sofosbuvir products for the degree and speed of virologic response to a dual anti-hepatitis C virus (HCV) treatment protocol. We aimed to test the applicability of the early virus response kinetics and the very rapid virologic response (vRVR) rate as quick outcome measures for accelerated comparative efficacy studies and as a foundation for a personalized response-guided therapy. Methods Fifty eligible chronic HCV patients were randomized to either one of two generic sofosbuvir products (Gratisovir or Grateziano) at a daily dose of one 400 mg tablet plus a weight-based ribavirin dose. Data were compared between the groups for early virus response kinetics and vRVR rates in relation to the rates of final sustained virologic response at week 12 posttreatment (SVR12). Results The Log10 transformed virus load (Log polymerase chain reaction) curves showed fairly similar rapid decline during the first 2 weeks, with no significant difference between the groups at four analysis points throughout the study by repeated-measures factorial analysis of variance test (P=0.48). The SVR12 rates were 96% (95% confidence interval, 79.6%–99.9%) in Gratisovir group (24/25) and 95.7% (95% confidence interval, 78%–99.9%) in Grateziano group (22/23). There was no statistically significant difference found by exact test (P>0.999). There was a significant association between the vRVR and the SVR12, with 100% positive predictive value (38/38 of those who had vRVR, achieved a final SVR12) and 82.6% sensitivity (among the total 46 with SVR12, 38 were having vRVR). Conclusion We can conclude from our study that the early HCV response kinetics and the vRVR rates could be used as sensitive quick markers for efficacy (with a very high positive predictive value for SVR12), based on our accelerated comparative efficacy research model. This might open the way for new models of accelerated equivalence

  2. Kinetic study on the effect of temperature on biogas production using a lab scale batch reactor.

    Science.gov (United States)

    Deepanraj, B; Sivasubramanian, V; Jayaraj, S

    2015-11-01

    In the present study, biogas production from food waste through anaerobic digestion was carried out in a 2l laboratory-scale batch reactor operating at different temperatures with a hydraulic retention time of 30 days. The reactors were operated with a solid concentration of 7.5% of total solids and pH 7. The food wastes used in this experiment were subjected to characterization studies before and after digestion. Modified Gompertz model and Logistic model were used for kinetic study of biogas production. The kinetic parameters, biogas yield potential of the substrate (B), the maximum biogas production rate (Rb) and the duration of lag phase (λ), coefficient of determination (R(2)) and root mean square error (RMSE) were estimated in each case. The effect of temperature on biogas production was evaluated experimentally and compared with the results of kinetic study. The results demonstrated that the reactor with operating temperature of 50°C achieved maximum cumulative biogas production of 7556ml with better biodegradation efficiency.

  3. Study on the Hydrolysis Kinetics of Xylan on Different Acid Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Na, Byeong-Il; Lee, Jae-Won [Chonnam National University, Gwangju (Korea, Republic of)

    2014-04-15

    In this study, we investigated kinetic model for the acid-catalyzed xylan hydrolysis at temperature 120-150 .deg. C. Also, we analyzed the kinetic parameters for xylose production and furfural decomposition. The hydrolysis of xylan and the degradation of xylose were promoted by high reaction temperature and acid concentration. The optimal hydrolysis condition for the highest reaction rate constants (k{sub 1}) was different depending on the acid catalysts. Among sulfuric, oxalic and maleic acid, the xylan reaction rate constants (k{sub 1}) to xylose had the highest value of 0.0241 min{sup -1} when 100 mM sulfuric acid was used at 120 .deg. C. However, sulfuric acid induced more xylose degradation compared to oxalic and maleic acid hydrolysis. The activation energy for xylan degradation was the highest when sulfuric acid was used.

  4. Kinetic study of the reaction of chlorine atoms with hydroxyacetone in gas-phase

    Science.gov (United States)

    Stoeffler, Clara; Joly, Lilian; Durry, Georges; Cousin, Julien; Dumelié, Nicolas; Bruyant, Aurélien; Roth, Estelle; Chakir, Abdelkhaleq

    2013-12-01

    In this letter the kinetics of the reaction of hydroxyacetone CH3C(O)CH2OH with Cl atoms is investigated using the relative rate technique. Experiments are carried out in a 65 L multipass photoreactor in the temperature range of 281-350 K. A mid-infrared spectrometer based on a quantum cascade laser in external cavity emitting at 9.5 μm is used to analyze the reactants. The determined rate coefficient for the investigated reaction is (1.7 ± 0.3) × 10-11exp(381.5 ± 57.3/T). The results are presented and discussed in terms of precision and compared with those obtained previously. The impact of Cl atoms on the atmospheric life time of hydroxyacetone is also discussed. Developing analytical techniques to quantify this compound in the atmosphere. Several methods of measurement have been used including the technique of proton transfer mass spectrometry (PTR-MS) [2] and derivatization with a chemical agent such as dinitrophenylhydrazine (DNPH) [3,4] followed by GC/MS or HPLC analyses. The HA amount in the troposphere was found to be in the order of a few hundred parts per trillion by volume [4], Performing laboratory experiments in order to study the HA reactivity with atmospheric oxidants. The first study on the kinetic of the reaction between OH radicals and HA was made by Dagault et al. [5] whose work was performed at room temperature by flash photolysis-resonance fluorescence. The determined rate constant implies a lifetime of a few days for HA relative to oxidation by OH radicals. Orlando et al. performed mechanistic and kinetics studies of the reaction of HA with OH radicals and Cl atoms at room temperature using a relative method [6]. Products detection was performed using FTIR spectroscopy. Moreover, these authors studied the photolysis of HA to determine its quantum yield and UV absorption spectrum. These studies showed that HA is principally removed from the atmosphere by reaction with OH radicals. Kinetic studies of the reaction of OH radicals with HA as a

  5. Study of the Drying Kinetics of Lemon Grass

    Directory of Open Access Journals (Sweden)

    Mustafa Ibrahim

    2009-01-01

    Full Text Available Problem statement: The thin- layer drying experiments were conducted to examine the effect of drying air temperature and humidity on the drying kinetics. Approach: A model to estimate the drying behavior of Lemon grass was developed. Results: Four different thin-layer drying models were compared with respect to their coefficient of determination (R2, Mean Bias Error (MBE and Root Mean Square Error (RMSE. The one with highest (R2 and lowest (MBE and (RMSE was selected to better estimate the drying curves. Three temperatures (35, 45 and 55°C and three humidities (30, 40 and 50% were investigated with a fixed air velocity of 1 m sec-1. Conclusion/Recommendation: The increase in the drying air temperature increased the drying process and decreased the Equilibrium Moisture Content (EMC of Lemon grass. The drying process decreased as the air humidity increases. The effect was less than that of the temperature. The EMC have high values with high relative humidity.

  6. Study of kinetics of co-pyrolysis of coal and waste LDPE blends under argon atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Sumedha Sharma; Aloke K. Ghoshal [Indian Institute of Technology Guwahati, Guwahati (India). Department of Chemical Engineering

    2010-12-15

    Co-pyrolysis of coal with waste plastic is increasingly being looked upon as a potential technique to counter the present day challenges in energy and waste management by harnessing the multiple benefits associated with the same. In the present work, the kinetics of co-pyrolysis of waste LDPE carried out with coal of Ledo origin from the coalfields of Assam (India) has been studied. A thermo-gravimetric (TG) study of the co-pyrolysis has been carried out taking waste LDPE-coal mixtures in ratios of 3:1, 1:1, and 1:3 by weight and at five varying heating rates from 5 to 25 K min{sup -1} with a 5 K increment. Experiments were also carried out for the individual components at all the five heating rates. This TG analysis data was used to evaluate the kinetics parameters such as the activation energy, pre-exponential factors, and the reaction orders, applying a model fitting approach. The results of the kinetics analysis indicate higher activation energy for the mixtures. With increase in the coal percentage, the reaction order is found to increase. Also the synergistic effect between the two sample species in the mixtures has been studied and found to indicate presence of interaction between coal and LDPE. The effect of sample composition on the products of co-pyrolysis has also been compared. 48 refs., 5 figs., 4 tabs.

  7. Kinetics study of carbon raiser on the reduction of nickel laterite from Pomalaa, Southeast Sulawesi

    Science.gov (United States)

    Petrus, H. T. B. M.; Rhamdani, A. R.; Putera, A. D. P.; Warmada, I. W.; Yuliansyad, A. T.; Perdana, I.

    2016-11-01

    As one of the top ten on nickel laterite ore resources in the world, Indonesia must have been initiating the nickel processing in total amount of about 1.5 million tonnes. In regard to the low nickel laterite processing, one of the possible product is nickel pig iron (NPI) needed for the stainless steel industries. In this study carbon raiser that is waste from oil industries was used to replace metalurgical coke. The kinetic of nickel laterite reduction using carbon raiser was studied and compared with anthrasite coal. In this work, the author conducted the reduction of nickel laterite ores by both carbon raiser and anthrasite coal as reductant, in air and CO2 atmosphere, within the temperature ranged from 800°C and 1000°C. Two models were applied, sphere particle geometry model and Ginstling-Brounhstein diffusion model, to study the kinetic parameters. The results indicated that type of reductants and reduction atmosphere greatly influence the kinetic parameters. The obtained values of activation energy were varied between 17.44-18.12 kcal/mol.

  8. Kinetic studies of alkaline phosphatase extracted from rabbit (Lepus ...

    African Journals Online (AJOL)

    user

    activity, and the kinetic constants-maximum enzyme velocity (Vmax) and Michealis-Menten ... at temperature greater than 44.95°C with corresponding catalytic energy of ..... potential biomarker for the intergrity of the hepatic drainage system.

  9. Studies on the kinetics and intraparticle diffusivities of BOD, colour ...

    African Journals Online (AJOL)

    EJIRO

    1Department of Industrial Chemistry, Abia State University, P. M. B. 2000, Uturu, Abia State, Nigeria. ..... chemical reaction equation (Ho and Wang 2004; Majid et al., 1999). ... time and the reactor dimensions controlled by the system's kinetics.

  10. Kinetic Study of Calcination of Jakura Limestone Using Power Rate ...

    African Journals Online (AJOL)

    National Research Institute for Chemical Technology, P.M. B 1052, Zaria, Kaduna State, Nigeria. [*Author ... calcination of Jakura limestone was also found to be first order reaction with respect to CaCO3 ..... Kinetics and Reactor Design, Gulp.

  11. An improved pyrite pretreatment protocol for kinetic and isotopic studies

    Science.gov (United States)

    Mirzoyan, Natella; Kamyshny, Alexey; Halevy, Itay

    2014-05-01

    An improved pyrite pretreatment protocol for kinetic and isotopic studies Natella Mirzoyan1, Alexey Kamyshny Jr.2, Itay Halevy1 1Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel 2Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel Pyrite is one of the most abundant and widespread of the sulfide minerals with a central role in biogeochemical cycles of iron and sulfur. Due to its diverse roles in the natural and anthropogenic sulfur cycle, pyrite has been extensively studied in various experimental investigations of the kinetics of its dissolution and oxidation, the isotopic fractionations associated with these reactions, and the microbiological processes involved. Pretreatment of pyrite for removal of oxidation impurities to prevent experimental artifacts and inaccuracies is often practiced. While numerous pyrite-cleaning methods have been used in experiments, a common pyrite pretreatment method, often used to investigate pyrite chemistry by the isotopic fractionations associated with it, includes several rinses by HCl, acetone and deionized water. Elemental sulfur (S0) is a common product of incomplete pyrite oxidation. Removal of S0 is desirable to avoid experimental biases associated with its participation in pyrite transformations, but is more complicated than the removal of sulfate. Although rinsing with an organic solvent is in part aimed at removing S0, to the best of our knowledge, the extraction efficiency of S0 in existing protocols has not been assessed. We have developed and tested a new protocol for elemental sulfur removal from the surface of pyrite by ultrasonication with warm acetone. Our data demonstrate the presence of large fractions of S0 on untreated pyrite particle surfaces, of which only approximately 60% was removed by the commonly used pretreatment method. The new protocol described here was found to be more efficient at S0 removal than the commonly used method

  12. Studies on kinetics and thermodynamics of biomachining pure copper

    Institute of Scientific and Technical Information of China (English)

    张德远; 李雅芹

    1999-01-01

    The kinetics and thermodynamics of biomachining pure copper by Thiobacillus ferrooxidans were quantitatively analyzed. The kinetic effect of bacteria on the ion-cycle between Fe2+ and Fe3+ and the thermodynamic effect of hydrolysis on the changes of pH in biomachining processes were expounded through six series of experiment. Finally a model of ion-cycle in the biomachining processes was proposed, and the measures for maintaining the stable equilibrium of the ion-cycle were also discussed.

  13. Constant composition kinetics study of carbonated apatite dissolution

    Science.gov (United States)

    Tang, Ruikang; Henneman, Zachary J.; Nancollas, George H.

    2003-03-01

    The carbonated apatites (CAP) may be more suitable models for biominerals such as bone and dental hard tissues than is pure hydroxyapatite (HAP) since they have similar chemical compositions. Although they contain only a relatively small amount of carbonate, the solubility and dissolution properties are different. The solubility product of the CAP particles used in this dissolution study, 2.88×10 -112 mol 18 l -18, was significantly greater than that of HAP, 5.52×10 -118 mol 18 l -18. The kinetics of dissolution of CAP has been studied using the constant composition (CC) method. At low undersaturations, the dissolution reaction appeared to be controlled mainly by surface diffusion with an effective reaction order of 1.9±0.1 with respect to the relative undersaturation. These results together with those obtained by scanning electron microscopy (SEM) suggest a dissolution model. Based on the surface diffusion theory of Burton, Cabrera and Frank (BCF). The interfacial tension between CAP and the aqueous phase calculated from this dissolution model, 9.0 m J m -2, was consistent with its relatively low solubility. An abnormal but interesting dissolution behavior is that the CAP dissolution rate was relatively insensitive to changes in calcium and phosphate concentrations at higher undersaturations, suggesting the importance of the carbonate component under these conditions.

  14. Kinetic study by FTIR and DSC on the cationic curing of a DGEBA/{gamma}-valerolactone mixture with ytterbium triflate as an initiator

    Energy Technology Data Exchange (ETDEWEB)

    Arasa, M. [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili. C/Marcel.li Domingo s/n, 43007 Tarragona (Spain); Ramis, X. [Laboratori de Termodinamica, ETSEIB. Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain)], E-mail: ramis@mmt.upc.edu; Salla, J.M. [Laboratori de Termodinamica, ETSEIB. Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Mantecon, A.; Serra, A. [Departament de Quimica Analitica i Quimica Organica, Universitat Rovira i Virgili. C/Marcel.li Domingo s/n, 43007 Tarragona (Spain)

    2008-12-05

    A mixture of diglycidylether of bisphenol A (DGEBA) and {gamma}-valerolactone ({gamma}-VL) was cured in the presence of ytterbium triflate as an initiator to obtain poly(esther-ether) thermosets. The kinetics of the various elemental reactions, which take place during the curing process, was studied by means of isothermal curing in the FTIR spectrometer. The kinetic parameters were calculated by means of the isoconversional procedure and the best-fit kinetic model was determined with the so-called compensation effect (isokinetic relationship). The isothermal kinetic analysis was compared with that obtained by dynamic curing in DSC.

  15. Kinetic studies on the etherification of C5-alkenes to fuel ether tame

    Energy Technology Data Exchange (ETDEWEB)

    Paeaekkoenen, P.

    2003-07-01

    Tertiary ethers are formed in reactions between alcohols and alkenes and are used in reformulated gasoline as octane-enhancing agents. By blending ethers into the gasoline pool, less ground-level ozone is formed and combustion of the gasoline is more efficient as a result of the oxygen boost. The main goal of this research was to study the synthesis of TAME (tert-amyl methyl ether, 2-methoxy-2-methylbutane) and to formulate a kinetic model as precise as possible for process design purposes. The reaction rate was studied as a function of temperature and the reagents feed molar ratio with conventional ion-exchange resin beads and a novel fibrous ion-exchange catalyst. Kinetic modelling favoured the Langmuir-Hinshelwood type model, derived from a dual-site mechanism for the etherification. The influence of the acid capacity of the catalysts on the reaction rate was found to be second order. These results suggest that the etherification reactions occur via a dual-site mechanism. Comparison of the values of the kinetic parameters obtained with a fibre catalyst and with a bead catalyst indicated that diffusion limitations are associated with the latter. Therefore, mass transfer of the reacting components inside the pores of the cationic ion- exchange resin bead was estimated in terms of the effectiveness factors calculated from experiments with different resin bead sizes. It was concluded that mass transfer has to be taken into account when applying the kinetic model, which was derived for resin beads as the catalyst. High temperatures and high alcohol concentrations favoured the formation of the dialkyl ethers (dehydration) as a side reaction. When the reaction was maintained in a kinetic regime, it was highly selective for tert-etherification, since the rate of tert-etherification was 140 to 270 times that of dehydration. The experimental results were best described with a model in which one alcohol molecule is adsorbed and the other reacts from the liquid phase. The

  16. Labeling of vasoactive intestinal peptide (VIP) and VIP 10-28 fragment with radioiodine by direct method. Comparative study of the kinetics biodistribution and affinity for neuroendocrine tumor cells; Marcacao do peptideo intestinal vasoativo (VIP) e do fragmento VIP10-28 com radioiodo por metodo direto. Estudo comparativo da cinetica de biodistribuicao e da afinidade por celulas de tumor neuroendocrino

    Energy Technology Data Exchange (ETDEWEB)

    Colturato, Maria Tereza

    2005-07-01

    In the progress of the Nuclear Medicine, many protein based radiopharmaceuticals have been developed in the last years using antibodies and, more recently, biologically active natural peptides or similar synthetic peptides. In the search for agents with specificity for the target tissue in tumors detection, it was verified that small sequences of amino acids may interact with selective sites, with homogenous distribution, fast accumulation in tissues and fast blood clearance when compared to the antibodies. Among the peptides used in the diagnosis of tumors, Vasoactive Intestinal Peptide (VIP) has been studied. VIP labeled with iodine-123 is applied in the images of intestinal adenocarcinoma and endocrine tumors. The molecule of VIP contains two tyrosine residues, in the positions 10 and 22 that are, theoretically, equally susceptible to radioiodination for direct method. The objective of this work was to produce VIP labeled with radioiodine (iodine-123), in order to introduce to the brazilian medical class this radiopharmaceutical of interest for the diagnosis and recurrence of tumors that express specific receptors. In an unpublished way, the work studied the labeling and the kinetic distribution of the VIP fragment (VIP 10-28) and verified its potential as radiopharmaceutical applied in the identification of tumors that express VIP receptors. After the choice of the appropriated technique for labeling VIP and VIP 10-28 with radioiodine, using Ceremonial T as oxidant agent and sodium metabisulfite as reducing agent, the quality control procedures were accomplished (electrophoresis and high performance liquid chromatography, HPLC) for radiochemical purity determination as well as the separation of the radiochemical species obtained. Labeling and quality control procedures applied were efficient and accurate. [{sup 131}I]VIP and [{sup 131}l]VIP 10-28 were obtained with high radiochemical purity (> 95%). The purification studies to remove free radioiodine in the

  17. Studies on drying kinetics of olive foot cake

    Directory of Open Access Journals (Sweden)

    Hamlat, M. S.

    2002-06-01

    Full Text Available The olive foot cake is a very important by-product of olive oil industry since it can contain until 12 % of oil which can be extracted using solvent. The used solvent is often immiscible with water. This is the reason why its effect is limited by the moisture of olive foot cake making its drying imperative. In this paper, we present the behaviour of olive foot cake subjected to convective drying. The experimental results show that the drying rate versus moisture presents only one period of decreasing rate. The influence of the main parameters on drying kinetics is studied.El orujo es un importante subproducto de la industria del aceite de oliva ya que puede contener hasta el 12 % del aceite, el cual puede ser extraído usando un disolvente apropiado. El uso del disolvente es a menudo inmiscible con el agua. Esta es la razón por la que su efecto está limitado por la humedad del orujo, haciendo su secado imperativo. En este artículo se presenta el comportamiento del orujo sometido a un secado por convección. Los resultados experimentales mostraron que la velocidad de secado frente a la humedad, presenta un solo período de disminución de dicha velocidad. Se ha estudiado la influencia de los principales parámetros sobre la cinética de secado.

  18. Kinetic study of seawater reverse osmosis membrane fouling

    KAUST Repository

    Khan, Muhammad

    2013-10-01

    Reverse osmosis (RO) membrane fouling is not a static state but a dynamic phenomenon. The investigation of fouling kinetics and dynamics of change in the composition of the foulant mass is essential to elucidate the mechanism of fouling and foulant-foulant interactions. The aim of this work was to study at a lab scale the fouling process with an emphasis on the changes in the relative composition of foulant material as a function of operating time. Fouled membrane samples were collected at 8 h, and 1, 2, and 4 weeks on a lab-scale RO unit operated in recirculation mode. Foulant characterization was performed by CLSM, AFM, ATR-FTIR, pyrolysis GC-MS, and ICP-MS techniques. Moreover, measurement of active biomass and analysis of microbial diversity were performed by ATP analysis and DNA extraction, followed by pyro-sequencing, respectively. A progressive increase in the abundance of almost all the foulant species was observed, but their relative proportion changed over the age of the fouling layer. Microbial population in all the membrane samples was dominated by specific groups/species belonging to Proteobacteria and Actinobacteria phyla; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age. © 2013 American Chemical Society.

  19. Kinetic Study of Nonequilibrium Plasma-Assisted Methane Steam Reforming

    Directory of Open Access Journals (Sweden)

    Hongtao Zheng

    2014-01-01

    Full Text Available To develop a detailed reaction mechanism for plasma-assisted methane steam reforming, a comprehensive numerical and experimental study of effect laws on methane conversion and products yield is performed at different steam to methane molar ratio (S/C, residence time s, and reaction temperatures. A CHEMKIN-PRO software with sensitivity analysis module and path flux analysis module was used for simulations. A set of comparisons show that the developed reaction mechanism can accurately predict methane conversion and the trend of products yield in different operating conditions. Using the developed reaction mechanism in plasma-assisted kinetic model, the reaction path flux analysis was carried out. The result shows that CH3 recombination is the limiting reaction for CO production and O is the critical species for CO production. Adding 40 wt.% Ni/SiO2 in discharge region has significantly promoted the yield of H2, CO, or CO2 in dielectric packed bed (DPB reactor. Plasma catalytic hybrid reforming experiment verifies the reaction path flux analysis tentatively.

  20. KINETIC MODELS STUDY OF HYDRODESULPHURIZATION VACUUM DISTILLATE REACTION

    Directory of Open Access Journals (Sweden)

    AbdulMunem A. Karim

    2013-05-01

    Full Text Available    This study deals with  kinetics of hydrodesulphurization (HDS reaction of vacuum gas oil (611-833 K which was distillated from Kirkuk crude oil and which was obtained by blending the fractions, light vacuum gas oil (611 - 650 K, medium vacuum gas oil (650-690 K, heavy vacuum gas oil (690-727 K and very heavy vacuum gas oil (727-833 K.   The vacuum gas oil was hydrotreated on a commercial cobalt-molybdenum alumina catalyst presulfied at specified conditions in a laboratory trickle bed reactor. The reaction temperature range (583-643 K,liquid hourly space velocity range (1.5-3.75 h-1 and hydrogen pressure was kept constant at 3.5 MPa with hydrogen to oil ratio about 250 lt/lt.           The conversion results for desulphurization reaction appeared to obey the second order reaction. According to this model, the rate constants for desulphurization reaction were determined. Finally, the apparent activation energy (Ea, enthalpy of activation ( H* and entropy ( S* were calculated based on the values of rate constant (k2 and were equal 80.3792 KJ/mole, 75.2974 KJ/mole and 197.493 J/mole, respectively.

  1. Photodegradation of the acaricide abamectin: a kinetic study.

    Science.gov (United States)

    Escalada, Juan Pablo; Gianotti, José; Pajares, Adriana; Massad, Walter A; Amat-Guerri, Francisco; García, Norman A

    2008-08-27

    The acaricide abamectin is a mixture of two colorless homologues in a molar ratio of at least 4:1 with the same structure of macrocyclic lactone. The kinetics of its degradation under direct (254 nm) and dye-sensitized (>400 nm) photoirradiation in methanol solution has been studied by UV-vis spectrophotometry, potentiometric detection of dissolved oxygen, stationary fluorescence, laser flash photolysis, and time-resolved detection of singlet molecular oxygen (O2((1)Delta(g))) phosphorescence. The results indicate that the degradation is very efficient under direct irradiation with UV light (254 nm), with a quantum yield of 0.23. On the contrary, under visible-light irradiation, using the natural pigment riboflavin or the synthetic dye rose bengal as sensitizers, the degradation is very inefficient and proceeds through a O2((1)Delta(g))-mediated mechanism, with a bimolecular rate constant for the overall O2((1)Delta(g)) quenching (the sum of physical and chemical quenching) of 5.5 x 10(5) M(-1) s(-1). This value is similar to those reported for the rate constants of the reactions of O2((1)Delta(g)) with isolated double bonds or conjugated dienes and points to similar processes in the case of abamectin.

  2. Kinetic study of the enzymatic hydrolysis of sugarcane bagasse

    Directory of Open Access Journals (Sweden)

    M. L. Carvalho

    2013-09-01

    Full Text Available This work presents a kinetic study of the enzymatic hydrolysis of three cellulosic substrates: filter paper (FP, used as a low recalcitrance substrate model; steam exploded sugarcane bagasse (SB; and weak acid pretreated SB (1:20 dry bagasse:H2SO4 solution 1% w/w, the last two delignified with 4% NaOH (w/w. The influence of substrate concentration was assessed in hydrolysis experiments in a shaker, using Accellerase® 1500, at pH 4.8, in 50 mM sodium citrate buffer. Cellulose loads (weight substrate/weight total were changed between 0.5%-13% (for FP and 0.99%-9.09% (for SB. For FP and low loads of steam exploded SB, it was possible to fit pseudo-homogeneous Michaelis-Menten models (with inhibition. For FP and higher loads of steam exploded SB, modified Michaelis-Menten models were fitted. Besides, it was observed that, after retuning of the model parameters, it is possible to apply a model fitted for one situation to a different case. Chrastil models were also fitted and they were the only feasible approach for the highly recalcitrant acid-treated SB.

  3. Biological conversion of synthesis gas. Mass transfer/kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Mass transfer and kinetic studies were carried out for the Rhodospirillum rubrum and Chlorobium thiosulfatophilum bacterial systems. R. rubrum is a photosynthetic anaerobic bacterium which catalyzes the biological water gas shift reaction: CO + H{sub 2}0 {yields} CO{sub 2} + H{sub 2}. C. thiosulfatophilum is also a H{sub 2}S and COS to elemental sulfur. The growth of R. rubrum may be satisfactorily carried out at 25{degree} and 30{degree}C, while CO uptake and thus the conversion of CO best occurs at temperatures of either 30{degree}, 32{degree} or 34{degree}C. The rate of conversion of COs and H{sub 2}O to CO{sub 2} and H{sub 2}S may be modeled by a first order rate expression. The rate constant at 30{degree}C was found to be 0.243 h{sup {minus}1}. The growth of C. thiosulfatophilum may be modeled in terms of incoming light intensity using a Monod equation: {mu} = {sub 351} + I{sub o}/{sup 0.152}I{sub o}. Comparisons of the growth of R. rubrum and C. thiosulfatophilum shows that the specific growth rate of C. thiosulfatophilum is much higher at a given light intensity.

  4. Kinetic study of ultrasonic antisolvent crystallization of sirolimus

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, P.J. [Chemical Engineering Department, S. V. National Institute of Technology, Surat 395007, Gujarat (India); Concept Medical Research Pvt. Ltd., Ground Floor, Narayan Darshan, Nr. Rupam Cinema, Salabatpura, Surat 395003, Gujarat (India); Murthy, Z.V.P.

    2010-03-15

    Sirolimus, generally used in organ transplantation, is derived from bacterium Streptomyces hygroscopicus. Mass transfer controlled ultrasonic antisolvent method was used for determining the precipitation kinetics of sirolimus. The effect of temperature was determined on the particles size, percentage recovery, critical radius of nucleus, mass transfer coefficient, etc. for sirolimus dissolved in methanol and antisolvent water using ultrasonic treatment. The study was done using classical nucleation theory, which can also be applied to precipitation processes. Experiments were carried out at various temperatures; viz: 45, 50, 60 and 70 C and the percentage recoveries of sirolimus were found to be 90.74, 91.5, 92.64 and 93.61%, respectively, for initial amount of 8 mg dissolved in 1 mL of solvent and further introduced into 12 mL of HPLC water. The final average diameters of crystals observed for the temperatures were 1371, 1287, 1063 and 863 nm, respectively. The systems were found to be mass transfer controlling and that the mass diffusivities were found to be about 3.97 x 10{sup -9}, 4.00 x 10{sup -9}, 3.01 x 10{sup -9} and 1.92 x 10{sup -9} m{sup 2}/s, respectively. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil to Liquid Fuels

    Directory of Open Access Journals (Sweden)

    Wara Dyah Pita Rengga

    2015-03-01

    Full Text Available Reaction kinetics of catalytic cracking of rubber seed oil to liquid fuels has been investigated. The reac-tion was performed with sulfuric acid as catalyst at temperatures of 350-450 oC and the ratio of oil-catalyst of 0-2 wt.% for 30-90 minutes. Kinetics was studied using the model of 6-lump parameters. The parameters were rubber seed oil, gasoline, kerosene, diesel, gas, and coke. Analysis of experimen-tal data using regression models to obtain reaction rate constants. Activation energies and pre-exponential factors were then calculated based on the Arrhenius equation. The simulation result illus-trated that the six-lump kinetic model can well predict the product yields of rubber seed oil catalytic cracking. The product has high selectivity for gasoline fraction as liquid fuel and the smallest amount of coke. The constant indicates that secondary reactions occurred in diesel products compared to gaso-line and kerosene. The predicted results indicate that catalytic cracking of rubber seed oil had better be conducted at 450 oC for 90 minutes using 0.5 wt.% catalyst. © 2015 BCREC UNDIP. All rights reservedReceived: 3rd December 2013; Revised: 5th December 2014; Accepted: 7th December 2014How to Cite: Rengga, W.D.P., Handayani, P.A., Kadarwati, S., Feinnudin, A.(2015. Kinetic Study on Catalytic Cracking of Rubber Seed (Hevea brasiliensis Oil  to Liquid Fuels. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (1: 50-60. (doi:10.9767/bcrec.10.1.5852.50-60Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.1.5852.50-60

  6. Physics studies in Europe; a comparative study

    NARCIS (Netherlands)

    Steenstrup, S; dalle Rose, LFD; Jones, WG; Tugulea, L; van Steenwijk, FJ

    What are the differences and similarities between physics studies at different universities across Europe (here the definition of Europe is broad)? How much does a student have to work to obtain a degree in physics? Questions like those prompted EUPEN (European Physics Education Network) to make a

  7. New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

    Directory of Open Access Journals (Sweden)

    Etienne Borré

    2010-12-01

    Full Text Available Seven novel Hoveyda–Grubbs precatalysts bearing an aminosulfonyl function are reported. Kinetic studies indicate an activity enhancement compared to Hoveyda’s precatalyst. A selection of these catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions.

  8. New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

    Science.gov (United States)

    Borré, Etienne; Caijo, Frederic

    2010-01-01

    Summary Seven novel Hoveyda–Grubbs precatalysts bearing an aminosulfonyl function are reported. Kinetic studies indicate an activity enhancement compared to Hoveyda’s precatalyst. A selection of these catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions. PMID:21165173

  9. Kinetic Studies on State of the Art Solid Oxide Cells

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Graves, Christopher R.; Mogensen, Mogens Bjerg;

    2016-01-01

    Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen/steam and refor......Electrochemical reaction kinetics at the electrodes of Solid Oxide Cells (SOCs) were investigated at 700 °C for two cells with different fuel electrode microstructures as well as on a third cell with a reduced active electrode area. Three fuel mixtures were investigated – hydrogen....../steam and reformate fuels hydrogen/carbon-dioxide and hydrogen/methane/steam. It was found that the kinetics at the fuel electrode were exactly the same in both reformates. The hydrogen/steam fuel displayed slightly faster kinetics than the reformate fuels. Furthermore the gas conversion impedance in the hydrogen...... into a single process as the gas conversion was reduced. The SOC with finer electrode microstructure displayed improved kinetics....

  10. Study on the thermal decomposition kinetics of nano-sized calcium carbonate

    Institute of Scientific and Technical Information of China (English)

    李代禧; 史鸿运; 邓洁; 徐元植

    2003-01-01

    This study of the thermal decomposition kinetics of various average diameter nano-particles of calcium carbonate by means of TG-DTA(thermogravimetry and differential thermal analysis) showed that the thermal decomposition kinetic mechanisms of the same crystal type of calcium carbonate samples do not vary with decreasing of their average diameters; their pseudo-active energy Ea; and that the top-temperature of decomposition Tp decreases gently in the scope of micron-sized diameter, but decreases sharply when the average diameter decreases from micron region to nanometer region. The extraordinary properties of nano-particles were explored by comparing the varying regularity of the mechanisms and kinetic parameters of the solid-phase reactions as well as their structural characterization with the variation of average diameters of particles. These show that the aggregation, surface effect as well as internal aberrance and stress of the nano-particles are the main reason causing both Ea and Tp to decline sharply with the decrease of the average diameter of nano-particles.

  11. Kinetic studies on the pyrolysis of asphaltenes from differenttypes of kerogens

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The pyrolysis kinetics of a series of asphaltenes, from different types of kerogens, are studied in this work. The results indicate that the distributions of activation energy are over a wide range for the asphaltenes from type I kerogens. There is still a large potential of hydrocarbon generation in case the activation energy is above 350 kJ·mol-1. While the distributions of activation energy are comparatively over a narrow range for the asphaltenes from type II and II kerogens,there is a little or almost no potential of hydrocarbon generation with the activation energy above 350 kJ·mol-1 respectively. For the asphaltenes from some specific type of kerogens, the pyrolysis kinetics can be applied to marking their maturity. Furthermore, based on detailed discussions of the kinetics parameter frequency factor, the asphaltenes from type I kerogens are considered to be of great potential to regenerate oils, while the asphaltenes' potential for oil-to-gas conversion tends to go down in order of primitive kerogen types of Ⅲ II and I.

  12. Kinetics, thermodynamics and mechanistic studies of carbofuran removal using biochars from tea waste and rice husks.

    Science.gov (United States)

    Vithanage, Meththika; Mayakaduwa, S S; Herath, Indika; Ok, Yong Sik; Mohan, Dinesh

    2016-05-01

    This study reports the thermodynamic application and non-linear kinetic models in order to postulate the mechanisms and compare the carbofuran adsorption behavior onto rice husk and tea waste derived biochars. Locally available rice husk and infused tea waste biochars were produced at 700 °C. Biochars were characterized by using proximate, ultimate and surface characterization methods. Batch experiments were conducted at 25, 35, and 45 °C for a series of carbofuran solutions ranging from 5 to 100 mg L(-1) with a biochar dose of 1 g L(-1) at pH 5.0 with acetate buffer. Molar O/C ratios indicated that rice husk biochar (RHBC700) is more hydrophilic than tea waste biochar (TWBC700). Negative ΔG (Gibbs free energy change) values indicated the feasibility of carbofuran adsorption on biochar. Increasing ΔG values with the rise in temperature indicated high favorability at higher temperatures for both RHBC and TWBC. Enthalpy values suggested the involvement of physisorption type interactions. Kinetic data modeling exhibited contribution of both physisorption, via pore diffusion, π*-π electron donor-acceptor interaction, H-bonding, and van der Waals dispersion forces and chemisorption via chemical bonding with phenolic, and amine groups. Equilibrium adsorption capacities of RHBC and TWBC determined by pseudo second order kinetic model were 25.2 and 10.2 mg g(-1), respectively.

  13. Inhibition of tyrosinase by 4H-chromene analogs: Synthesis, kinetic studies, and computational analysis.

    Science.gov (United States)

    Brasil, Edikarlos M; Canavieira, Luciana M; Cardoso, Érica T C; Silva, Edilene O; Lameira, Jerônimo; Nascimento, José L M; Eifler-Lima, Vera L; Macchi, Barbarella M; Sriram, Dharmarajan; Bernhardt, Paul V; Silva, José Rogério Araújo; Williams, Craig M; Alves, Cláudio N

    2017-04-08

    Inhibition of mushroom tyrosinase was observed with synthetic dihydropyrano[3,2-b]chromenediones. Among them, DHPC04 displayed the most potent tyrosinase inhibitory activity with a Ki value of 4 μm, comparable to the reference standard inhibitor kojic acid. A kinetic study suggested that these synthetic heterocyclic compounds behave as competitive inhibitors for the L-DOPA binding site of the enzyme. Furthermore, molecular modeling provided important insight into the mechanism of binding interactions with the tyrosinase copper active site. © 2017 John Wiley & Sons A/S.

  14. Aspects of Metal-YSZ Electrode Kinetics Studied using Model Electrodes

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Ebbesen, Sune; Mogensen, Mogens Bjerg

    2009-01-01

    The electrode kinetics of oxidation and reduction of H2/H2O and CO/CO2 at the metal/yttria stabilized zirconia (YSZ) interface were studied using model metal wire electrodes contacting polished YSZ pellets. The intent was to probe the reaction mechanisms by comparing the same reactions using...... different metals (Ag, Au, Cu, Ni, Pd, and Pt) under identical conditions relevant to fuel cell and electrolysis cell operation (e.g. including 50% H2/H2O and 50% CO/CO2). Impedance spectra were measured at open-circuit voltage and under polarization, and polarization sweeps were performed. The gas...

  15. Study on kinetics of hydrocarbon generation from coals in the Qinshui Basin

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi; WU Baoxiang; ZHENG Chaoyang; WANG Chuanyuan; ZHANG Hui; TAO Mingxin; LIU Jinzhong; ZHANG Xiaojun

    2005-01-01

    A new method for the quantitative assessment of hydrocarbon generation potential from coals by means of the chemical reaction kinetics has been developed gradually over the recent years. In this paper, the kinetic parameters of hydrocarbon gas generation are determined by high temperature and pressure, and closed- system thermal simulation for Late Paleozoic coals in the Qinshui Basin and the kinetic characteristics and the histories of hydrocarbon gas generation were studied using the parameters obtained. Results show that during the longer period from the Triassic (T) to the Middle Jurassic (J2), the coal-derived methane yield increased more slowly under lower palaeogeotemperature in the Qinshui Basin; however, the shorter period from Late Jurassic to Early Cretaceous, the coal-derived methane yield increased more rapidly under higher palaeogeotemperature. The correlation between the thermal simulation and the factual data shows that C1/ (C1+C2―4) coefficients computed by the histories of methane and C2―C4 hydrocarbon generation can provide evidence for the identification of the genesis of coal bed gas in the different areas of the Qinshui Basin. The kinetic simulating experiment of hydrocarbon generation for the peat considered as the original matter of coal formation was performed for the first time and the simulated results were compared with the characteristics of hydrocarbon generation from coals undergoing various palaeogeotemperature in the Qinshui Basin. The result indicates that the peat has a higher potential of hydrocarbon generation than that of coals. Therefore, the hydrocarbon generation results obtained from kinetic simulation for coal with higher maturation rank could not stand for their original hydrocarbon generation potential and thus would lead to an underestimation for coal-bed gas resource. The generative amount of coal-derived gas in the Qinshui Basin was predicted using kinetic simulation results for the peat and their maximum was

  16. Studies on Macro—kinetics of Gas Phase Polymerization of Butadiene with Rare—earch Catalyst

    Institute of Scientific and Technical Information of China (English)

    FANGDonyu; SUNJianzhong; 等

    2002-01-01

    The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on neodymium(Nd) was carried out.The effects of reaction temperature,reaction pressure,dispersing medium, and types of catalyst on kinetics of polymerization were investigated .A kinetic model with two kinds of active sites was proposed.The results show that the effects of the reaction temperature and the types of dispersing medium and catalyst on the kinetic performance of polymerization are significant,and that the combined model of first and second order decay of active site of catalyst can be used to describe the phenomena.

  17. New Combustion Regimes and Kinetic Studies of Plasma Assisted Combustion

    Science.gov (United States)

    2012-11-01

    Tasks 8 and 9: Kinetic model validation) Today’s Presentation 2. Multispecies diagnostics in a flow reactor with Mid-IR and molecular beam mass...S-Curve Competition between low T RO2 kinetics high T chain branching reactions 0.00 0.02 0.04 0.06 0.08 0.10 0.12 1x10 5 2x10 5 3x10 5 4x10...in Plasma assisted combustion • LTC in turbulent combustion at engine time scales 0-D modeling of DME /O2/He (0.03/0.1/0.896) ignition, P = 72

  18. Kinetic and mechanistic studies of allicin as an antioxidant.

    Science.gov (United States)

    Okada, Youji; Tanaka, Kaoru; Sato, Eisuke; Okajima, Haruo

    2006-11-21

    We have undertaken a detailed study of the antioxidant activity of allicin, one of the main thiosulfinates in garlic, in order to obtain quantitative information on it as a chain-breaking antioxidant. The antioxidant actions of allicin against the oxidation of cumene and methyl linoleate (ML) in chlorobenzene were studied in detail using HPLC. The hydroperoxides formed during the course of the inhibited oxidation of ML were analyzed as their corresponding alcohols by HPLC, and it is apparent that an allylic hydrogen atom of the allicin is responsible for the antioxidant activity. Furthermore, it is clear that the radical-scavenging reactions of allicin proceed via a one-step hydrogen atom transfer based on the results of the reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH) in the presence of Mg2+ and calculation of the ionization potential value. In addition, we determined the stoichiometric factor (n), the number of peroxyl radicals trapped by one antioxidant molecule, of allicin by measuring the reactivity toward DPPH in chlorobenzene, and the value of n for allicin was about 1.0. Therefore, we measured the rate constants, k(inh), for the reaction of allicin with peroxyl radicals during the induction period of the cumene and the ML oxidation. As a result, we found that allicin reacts with peroxyl radicals derived from cumene and ML with the rate constants k(inh) = 2.6 x 10(3) M(-1)s(-1) and 1.6 x 10(5) M(-1)s(-1) in chlorobenzene, respectively. Our results demonstrate for the first time reliable quantitative kinetic data and the antioxidative mechanism of allicin as an antioxidant.

  19. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  20. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Yunyan; Ma, Qisheng; Ellis, Geoffrey S.; Dai, Jinxing; Katz, Barry; Zhang, Shuichang; Tang, Yongchun

    2011-05-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2 cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using δD values in ethane from several basins in the world are in close agreement with similar predictions based on the δ 13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that δD values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that δD values in ethane might be more suitable for modeling than comparable values in methane and propane.

  1. The Influence Studies in Comparative Literature

    Institute of Scientific and Technical Information of China (English)

    张宏莹

    2010-01-01

    Comparative literature arose in the 19th century,the approach adopted for its influence study has been developed and diversified in different eras,in this article,the influence study in comparative literature through a reading culture is discussed in order to reveal in what aspects the reading culture may cut across the regional border of influence study.

  2. Kinetic studies of the sucrose adsorption onto an alumina interface

    Science.gov (United States)

    Singh, Kaman; Mohan, Sudhanshu

    2004-01-01

    An account is given of an experimental kinetic study of adsorption of analar reagent sucrose (ARS) onto an alumina interface spectrometrically ( λmax=570 nm) at pH 8.0 and at room temperature. The adsorption isotherm is a typical Langmuirian isotherm (S-type) and adsorption parameters have been deduced according to the Langmuir's model. The adsorption coefficient evaluated from the Langmuir's equation was found to be 2.52×10 2 l mol -1. Adsorption mechanism has been interpreted on the basis of metal-saccharide interaction as found in organometallic compounds and interaction due to negatively charged ends on the disaccharide molecules and positively charge groups on the surface on alumina which depends on the pH value. The effects of variation in experimental conditions of the adsorption system have also been investigated. The adsorption exhibited a typical response to the pH effect and on going towards the PZC the net charge decreases and any reaction making dependence on charge and maximum adsorption (amount) was found near the isoelectric point of alumina (pH 9.0). The presence of ions like Cl -, SO 42- and PO 43- affect the adsorbed amount quantitatively and it seems that these anions compete with sucrose for the positively charged surface sites. The addition of similar concentration of cations was found to reduce the adsorbed amount. The temperature was found to have an inverse effect on adsorption. The additions of catonic and anionic detergents influence both the adsorbed amount and the adsorption rate. The thermodynamics of the titled adsorption model indicates the spontaneous and exothermic nature. The negative value of entropy is an indication of probability of favorable and complex nature of the adsorption.

  3. Kinetic study of sphingomyelin hydrolysis for ceramide production

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    2008-01-01

    in cosmetic and pharmaceutical industries such as in hair and skin care products. The enzymatic hydrolysis of sphingomyelin has been proved to be a feasible method to produce ceramide. The kinetic performance of sphingomyelin hydrolysis in the optimal two-phase (water:organic solvent) reaction system...

  4. Kinetic Studies on Ni-YSZ Composite Electrodes

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Sudireddy, Bhaskar Reddy; Hjelm, Johan;

    2015-01-01

    AC and DC techniques were applied to investigate the electrochemical reaction kinetics of porous composite Ni/8-mol% yttria-stabilized zirconia (Ni/8YSZ) solid oxide cell (SOC) electrodes using a novel pseudo-3-electrode cell geometry. From OCV impedance spectra an activation energy Ea of 1.13 eV...

  5. An Undergraduate Laboratory Exercise for Studying Kinetics of Batch Crystallization

    Science.gov (United States)

    Louhi­-Kultanen, Marjatta; Han, Bing; Nurkka, Annikka; Hatakka, Henry

    2015-01-01

    The present work describes an undergraduate laboratory exercise for improving understanding of fundamental phenomena in cooling crystallization. The exercise of nucleation and crystal growth kinetics supports learning of theories and models presented in lectures and calculation exercises. The teaching methodology incorporates precepts the…

  6. Kinetic Studies of Alkaline Phosphatase from the Liver of Agama ...

    African Journals Online (AJOL)

    Spectrophotometric method was used to assay the enzyme, and the kinetic constants: Maximum velocity (Vmax) ... was monitored by monitoring rate of hydrolysis of para – ... tubes to start the reaction at interval of 5 min for 30 min. The reaction ...

  7. Kinetic Studies of the Solvolysis of Two Organic Halides

    Science.gov (United States)

    Duncan, J. A.; Pasto, D. J.

    1975-01-01

    Describes an undergraduate organic chemistry laboratory experiment which utilizes the solvolysis of organic halides to demonstrate first and second order reaction kinetics. The experiment also investigates the effect of a change of solvent polarity on reaction rate, common-ion and noncommon-ion salt effects, and the activation parameters of a…

  8. Synthesis, kinetic mechanism and docking studies of vanillin derivatives as inhibitors of mushroom tyrosinase.

    Science.gov (United States)

    Ashraf, Zaman; Rafiq, Muhammad; Seo, Sung-Yum; Babar, Mustafeez Mujtaba; Zaidi, Najam-us-Sahar Sadaf

    2015-09-01

    The purpose of the present study was to discover the extent of contribution to antityrosinase activity by adding hydroxy substituted benzoic acid, cinnamic acid and piperazine residues to vanillin. The study showed the transformation of vanillin into esters as shown in (4a-4d), (6a-6b), and (8a-8b). In addition, the relationship between structures of these esters and their mushroom tyrosinase inhibitory activity was explored. The kinetics of inhibition on mushroom tyrosinase by these esters was also investigated. It was found that hydroxyl substituted benzoic acid derivatives were weak inhibitors; however hydroxy or chloro substituted cinnamic acid and piperazine substituted derivatives were able to induce significant tyrosinase inhibition. The mushroom tyrosinase (PDBID 2ZWE) was docked with synthesized vanillin derivatives and their calculated binding energies were compared with experimental IC50 values which provided positive correlation. The most potent derivative 2-(4-formyl-2-methoxyphenoxy)-2-oxoethyl (2E)-3-(4-hydroxyphenyl)prop-2-enoate (6a) possesses hydroxy substituted cinnamic acid scaffold having IC50 value 16.13 μM with binding energy of -7.2 kcal/mol. The tyrosinase inhibitory activity of (6a) is comparable with standard kojic acid. Kinetic analysis indicated that compound 6a was mixed-type tyrosinase inhibitor with inhibition constant values Ki (13 μM) and Ki' (53 μM) and formed reversible enzyme inhibitor complex. The active vanillin analog (6a) was devoid of toxic effects as shown in cytotoxic studies.

  9. Size dependence of adsorption kinetics of nano-MgO: a theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuting; Wen, Yanzhen; Cui, Zixiang; Xue, Yongqiang, E-mail: xyqlw@126.com [Taiyuan University of Technology (China)

    2016-01-15

    Nanoparticles present tremendous differences in adsorption kinetics compared with corresponding bulk particles which have great influences on the applications of nanoparticles. A size-dependent adsorption kinetic theory was proposed, the relations between adsorption kinetic parameters, respectively, and particle size of nano-adsorbent were derived theoretically, and the influence mechanism of particle size on the adsorption kinetic parameters was discussed. In experiment, nanoscale magnesium oxide (nano-MgO) with different diameters between 11.5 and 41.4 nm with narrow size distribution and low agglomeration were prepared, and the kinetic parameters of adsorption of benzene on nano-MgO in aqueous solution were obtained. Then the influence regularities of the particle size on the adsorption kinetic parameters were obtained. The experimental results are consistent with the nano-adsorption kinetic theory. With particle size decreasing, the adsorption rate constant increases; the adsorption activation energy and the adsorption pre-exponential factor decrease. Furthermore, the logarithm of adsorption rate constant, the adsorption activation energy, and the logarithm of adsorption pre-exponential factor are linearly related to the reciprocal of particle diameter, respectively. The mechanism of particle size influence on the kinetic parameters is that the activation energy is influenced by the molar surface enthalpy of nano-adsorbent, the pre-exponential factor by the molar surface entropy, and the rate constant by both the molar surface enthalpy and the molar surface entropy.

  10. STUDY ON THE PHASE TRANSITION KINETICS OF THERMOTROPIC LIQUID CRYSTALLINE AROMATIC-ALIPHATIC COPOLYESTER

    Institute of Scientific and Technical Information of China (English)

    LI Minhui; WANG Xiaogong; LIU Deshan; ZHOU Qixiang

    1991-01-01

    The phase transition kinetics of thermotropic liquid crystalline aromatic-aliphatic regular copolyester:(X) were studied by DSC. By means of Kissinger's method the kinetic equation and parameters including activation energy, rate order and preexponential factor for phase transition from nematic to isotropic were obtained. The activation energy from crystal to nematic was also presented.

  11. Nickel and cobalt sorption on anaerobic granular sludges: kinetic and equilibrium studies

    NARCIS (Netherlands)

    Hullebusch, van E.D.; Zandvoort, M.H.; Lens, P.N.L.

    2004-01-01

    The kinetics and equilibria of sorption of the divalent metal ions cobalt and nickel onto anaerobic granular sludge are described. Single component and binary equimolar systems were studied at different pH values (pH 6, 7 and 8). The kinetic modelling of metal sorption by anaerobic granular sludge h

  12. Novel swirl-flow reactor for kinetic studies of semiconductor photocatalysis

    NARCIS (Netherlands)

    Ray, A.K; Beenackers, A.A C M

    1997-01-01

    A new two-phase swirl-flow monolithic-type reactor was designed to study the kinetics of heterogeneous photocatalytic processes on immobilized semiconductor catalysts. True kinetic rate constants for destruction of a textile dye were measured as a function of wavelength of light intensity and angle

  13. Very rapid virologic response and early HCV response kinetics, as quick measures to compare efficacy and guide a personalized response-guided therapy

    Directory of Open Access Journals (Sweden)

    Yakoot M

    2016-08-01

    Full Text Available Mostafa Yakoot,1,2 Alaa M Abdo,3 Ahmed Yousry,4,5 Sherine Helmy6 1Green Clinical Research Center, 2Abbas Helmy Clinics, 3Tropical Medicine and Hepatology Department, Alexandria Faculty of Medicine, 4Microbiology Department, High Institute of Public Health, Alexandria University, 5Mabarat Asafra Labs, 6Pharco Corporation, Alexandria, Egypt Background: This is the second and final report for our study designed to compare two generic sofosbuvir products for the degree and speed of virologic response to a dual anti-hepatitis C virus (HCV treatment protocol. We aimed to test the applicability of the early virus response kinetics and the very rapid virologic response (vRVR rate as quick outcome measures for accelerated comparative efficacy studies and as a foundation for a personalized response-guided therapy.Methods: Fifty eligible chronic HCV patients were randomized to either one of two generic sofosbuvir products (Gratisovir or Grateziano at a daily dose of one 400 mg tablet plus a weight-based ribavirin dose. Data were compared between the groups for early virus response kinetics and vRVR rates in relation to the rates of final sustained virologic response at week 12 posttreatment (SVR12.Results: The Log10 transformed virus load (Log polymerase chain reaction curves showed fairly similar rapid decline during the first 2 weeks, with no significant difference between the groups at four analysis points throughout the study by repeated-measures factorial analysis of variance test (P=0.48. The SVR12 rates were 96% (95% confidence interval, 79.6%–99.9% in Gratisovir group (24/25 and 95.7% (95% confidence interval, 78%–99.9% in Grateziano group (22/23. There was no statistically significant difference found by exact test (P>0.999. There was a significant association between the vRVR and the SVR12, with 100% positive predictive value (38/38 of those who had vRVR, achieved a final SVR12 and 82.6% sensitivity (among the total 46 with SVR12, 38 were

  14. Stabilization and transformation of amorphous calcium carbonate: structural and kinetic studies

    Science.gov (United States)

    Schmidt, Millicent Promise

    Amorphous calcium carbonate (ACC) is a common transient precursor in the formation of more stable crystalline calcium carbonate minerals, most notably calcite, vaterite, and aragonite. Formation of ACC from calcium carbonate rich aqueous solution rather than direct crystallization of crystalline polymorphs by organisms provides several advantages: control of morphology, grain size, orientation, hardness, and other bulk properties as well as reduction of energy costs during growth cycles. Despite decades of study, stabilization and transformation mechanisms of synthetic and biogenic ACC remain unclear. In particular, the roles of H2O and inorganic phosphate in ACC structure and transformation, and the variables affecting transformation kinetics and polymorph selection are understudied. In this research, we addressed structure and kinetic behavior of ACC through four complementary investigations: two studies focus on synthetic ACC stabilization and two focus on synthetic and biogenic ACC transformation behavior in solution at ambient temperatures. We explored ACC stabilization via compositional and thermal analyses, X-ray scattering, X-ray absorption spectroscopy, and nuclear magnetic resonance spectroscopy. Transformation experiments used a novel method of in situ structural analysis that provided quantitative kinetic and structural data and allowed us to visualize the ACC transformation pathway. Results revealed the complexity of H2O structure in ACC samples synthesized from three methods, indicating that the distinct hydrous populations produced define ACC behavior. Transformation kinetics and polymorph selection were strongly affected by the hydration state and type of synthetic ACC reacted. In situ transformation experiments also showed differences in kinetic behavior due to reaction medium. The structural role of hydrous components was again evident in in situ transformation experiments for ACC from a biogenic lobster gastrolith (LG) reacted with water. LG

  15. Atmospheric degradation of 3-methylfuran: kinetic and products study

    Directory of Open Access Journals (Sweden)

    A. Tapia

    2011-04-01

    Full Text Available A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases, using a relative method with different experimental techniques. The rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1 kOH = (1.13 ± 0.22 × 10−10 and kNO3 = (1.26 ± 0.18 × 10−11. Products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NO have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones in the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones in the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds in the reaction with NO3 radicals. The results indicate that, in all cases, the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for Cl atoms and NO3 radicals in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.

  16. Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

    Science.gov (United States)

    Tang, T. F.; Xu, X. Q.; Ma, C. H.; Bass, E. M.; Holland, C.; Candy, J.

    2016-03-01

    A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan based on "Cyclone base case parameter set." We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.

  17. Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

    Energy Technology Data Exchange (ETDEWEB)

    Tang, T. F. [Dalian University of Technology, Dalian 116024 (China); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Xu, X. Q. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Ma, C. H. [Fusion Simulation Center, School of Physics, Peking University, Beijing (China); Bass, E. M.; Candy, J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Holland, C. [University of California San Diego, La Jolla, California 92093-0429 (United States)

    2016-03-15

    A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan based on “Cyclone base case parameter set.” We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.

  18. Study on the Adsorption Kinetics of Acid Red 3B on Expanded Graphite

    Directory of Open Access Journals (Sweden)

    Xiu-yan Pang

    2008-01-01

    Full Text Available Expanded graphite (EG is a kind of important adsorbent for organic compound such as oil and dyes. We have investigated the adsorption kinetics characteristics of this adsorbent for dye. EG was prepared with 50 mesh crude graphite through chemical oxidation intercalation of potassium permanganate and vitriol, and dye of acid red 3B was used as model sorbate. We have studied the adsorption kinetic models and rate-limiting step of the process. Adsorption rate and activation energy of the adsorption process were calculated. Kinetic studies show that the kinetic data are well described by the pseudo second-order kinetic model. The equilibrium adsorbance increases with the increase of the initial acid red 3B concentration. Initial adsorption rate increases with the increase of the initial dye concentration and temperature. Adsorption process of acid red 3B on EG has small activation energy. Internal diffusion appears to be the rate-limiting step for the adsorption process.

  19. Delithiation kinetics study of carbon coated and carbon free LiFePO4

    Science.gov (United States)

    Lepage, D.; Sobh, F.; Kuss, C.; Liang, G.; Schougaard, S. B.

    2014-06-01

    A chemical oxidation method was employed to measure the kinetics of lithium release from LiFePO4 during oxidation. Similar to potential step measurements, the chemical method simplifies quantification compared to the common electrochemical techniques (PITT, GITT etc.). It was found that the overall release of lithium fits one dimensional diffusion kinetics, however, it is also shown that the mechanism must be more complex as the derived activation energy led to an unusually low attack rate of ∼108 Hz. A comparison of carbon coated/carbon free LiFePO4 samples indicated that the carbon coating has only a marginal effect on the delithiation kinetics.

  20. Ab initio and kinetic modeling studies of formic acid oxidation

    DEFF Research Database (Denmark)

    Marshall, Paul; Glarborg, Peter

    2015-01-01

    A detailed chemical kinetic model for oxidation of formic acid (HOCHO) in flames has been developed, based on theoretical work and data from literature. Ab initio calculations were used to obtain rate coefficients for reactions of HOCHO with H, O, and HO2. Modeling predictions with the mechanism...... as the fate of HOCO, determines the oxidation rate of formic acid. At lower temperatures HO2, formed from HOCO + O2, is an important chain carrier and modeling predictions become sensitive to the HOCHO + HO2 reaction. © 2014 The Combustion Institute....... on calculations with the kinetic model. Formic acid is consumed mainly by reaction with OH, yielding OCHO, which dissociates rapidly to CO2 + H, and HOCO, which may dissociate to CO + OH or CO2 + H, or react with H, OH, or O2 to form more stable products. The branching fraction of the HOCHO + OH reaction, as well...

  1. Hydroxylamine nitrate self-catalytic kinetics study with adiabatic calorimetry.

    Science.gov (United States)

    Liu, Lijun; Wei, Chunyang; Guo, Yuyan; Rogers, William J; Sam Mannan, M

    2009-03-15

    Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine compound family with applications that include equipment decontamination in the nuclear industry and aqueous or solid propellants. Due to its instability and autocatalytic behavior, HAN has been involved in several incidents at the Hanford and Savannah River Site (SRS) [Technical Report on Hydroxylamine Nitrate, US Department of Energy, 1998]. Much research has been conducted on HAN in different areas, such as combustion mechanism, decomposition mechanism, and runaway behavior. However, the autocatalytic decomposition behavior of HAN at runaway stage has not been fully addressed due to its highly exothermic and rapid decomposition behavior. This work is focused on extracting HAN autocatalytic kinetics and analyzing HAN critical behavior from adiabatic calorimetry measurements. A lumped autocatalytic kinetic model for HAN and associated model parameters are determined. Also the storage and handling critical conditions of diluted HAN solution without metal presence are quantified.

  2. Kinetic studies of HIV-1 and HIV-2 envelope glycoprotein-mediated fusion

    Directory of Open Access Journals (Sweden)

    Doms Robert W

    2006-12-01

    Full Text Available Abstract Background HIV envelope glycoprotein (Env-mediated fusion is driven by the concerted coalescence of the HIV gp41 N-helical and C-helical regions, which results in the formation of 6 helix bundles. Kinetics of HIV Env-mediated fusion is an important determinant of sensitivity to entry inhibitors and antibodies. However, the parameters that govern the HIV Env fusion cascade have yet to be fully elucidated. We address this issue by comparing the kinetics HIV-1IIIB Env with those mediated by HIV-2 from two strains with different affinities for CD4 and CXCR4. Results HIV-1 and HIV-2 Env-mediated cell fusion occurred with half times of about 60 and 30 min, respectively. Binding experiments of soluble HIV gp120 proteins to CD4 and co-receptor did not correlate with the differences in kinetics of fusion mediated by the three different HIV Envs. However, escape from inhibition by reagents that block gp120-CD4 binding, CD4-induced CXCR4 binding and 6-helix bundle formation, respectively, indicated large difference between HIV-1 and HIV-2 envelope glycoproteins in their CD4-induced rates of engagement with CXCR4. Conclusion The HIV-2 Env proteins studied here exhibited a significantly reduced window of time between the engagement of gp120 with CD4 and exposure of the CXCR4 binding site on gp120 as compared with HIV-1IIIB Env. The efficiency with which HIV-2 Env undergoes this CD4-induced conformational change is the major cause of the relatively rapid rate of HIV-2 Env mediated-fusion.

  3. Hydrogen production by thermal partial oxidation of ethanol: Thermodynamics and kinetics study

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamamre, Z. [Chemical Engineering Department, Faculty of Engineering and Technology, University of Jordan, 11942 Amman (Jordan); Hararah, M.A. [Environmental Engineering Department, Faculty of Engineering, Al-Hussein Bin Talal University, Ma' an (Jordan)

    2010-06-15

    In this study thermodynamics and kinetics analysis of the thermal partial oxidation (TPOX) of ethanol for producing hydrogen is performed. Equilibrium and kinetics calculations are performed in order to find the limiting parameters for the thermal partial oxidation. The effects of air ratio {lambda} (the ratio of the oxidizer -to- fuel ratio to the stoichiometric oxidizer -to- fuel ratio) and mixture inlet temperatures (T{sub mix-in}) on the reforming efficiency, the H{sub 2} mole number, the reaction progress, the equilibrium time and the ignition delay time are investigated. Furthermore, the analysis is performed using different kinetics schemes and the results are compared. The optimum practical operating conditions of the partial oxidation process of ethanol are identified. In this way, the results of this work can be useful as a guideline in experimental work. It is found that the reforming efficiency increases with increasing the process temperature for {lambda} < 0.3 and remains nearly constant elsewhere. The efficiency reaches a maximum value of 90% at {lambda} = 0.20 and T{sub mix-in} {>=} 1000 K. The kinetics simulations suggest that three different regions exist during the partial oxidation process of ethanol: the oxidation region, the water gas shift reaction- reforming region and the reforming region. The reforming reactions in the 3rd region are the reaction process limiting step. Additionally, it is found that the equilibrium concentration of a given species is not affected by the pressure when the process temperature lies outside the range of 500 K < T{sub process} < 1700 K. However, the minimum time required for a given species to reach the equilibrium is affected when pressures higher than 1 atm are employed. Pressures higher than 1 atm shift this minimum time towards lower values. Due to preheating limitations (self ignition and reactor material stability) and the kinetics behavior of the TPOX process of ethanol, practical operating conditions

  4. Kinetic studies of divertor heat fluxes in Alcator C-Mod

    Science.gov (United States)

    Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Rafiq, T.; Park, G. Y.; Chang, C. S.; Brunner, D.; Hughes, J. W.; Labombard, B.; Terry, J.

    2010-11-01

    The kinetic XGC0 code [C.S. Chang et al, Phys. Plasmas 11 (2004) 2649] is used to model the H- mode pedestal and SOL regions in Alcator C-Mod discharges. The self-consistent simulations in this study include kinetic neoclassical physics and anomalous transport models along with the ExB flow shear effects. The heat fluxes on the divertor plates are computed and the fluxes to the outer plate are compared with experimental observations. The dynamics of the radial electric field near the separatrix and in the SOL region are computed with the XGC0 code, and the effect of the anomalous transport on the heat fluxes in the SOL region is investigated. In particular, the particle and thermal diffusivities obtained in the analysis mode are compared with predictions from the theory-based anomalous transport models such as MMM95 [G. Bateman et al, Phys. Plasmas 5 (1998) 1793] and DRIBM [T. Rafiq et al, to appear in Phys. Plasmas (2010)]. It is found that there is a notable pinch effect in the inner separatrix region. Possible physical mechanisms for the particle and thermal pinches are discussed.

  5. Kinetic studies of nitrate removal from aqueous solution using granular chitosan-Fe(III) complex.

    Science.gov (United States)

    Hu, Qili; Chen, Nan; Feng, Chuanping; Zhang, Jing; Hu, Weiwu; Lv, Long

    2016-01-01

    In the present study, a granular chitosan-Fe(III) complex was prepared as a feasible adsorbent for the removal of nitrate from an aqueous solution. There was no significant change in terms of nitrate removal efficiency over a wide pH range of 3-11. Nitrate adsorption on the chitosan-Fe(III) complex followed the Langmuir-Freundlich isotherm model. In order to more accurately reflect adsorption and desorption behaviors at the solid/solution interface, kinetic model I and kinetic model II were proposed to simulate the interfacial process in a batch system. Nitrate adsorption on the chitosan-Fe(III) complex followed the pseudo-first-order kinetic model and kinetic model I. The proposed half-time could provide useful information for optimizing process design. Adsorption and desorption rate constants obtained from kinetic model I and kinetic model II were beneficial to understanding the interfacial process and the extent of adsorption reaction. Kinetic model I and kinetic model II implied that nitrate uptake exponentially approaches a limiting value.

  6. KINETIC STUDY OF COAL AND BIOMASS CO-PYROLYSIS USING THERMOGRAVIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ping; Hedges, Sheila; Chaudharib, Kiran; Turtonb, Richard

    2013-10-29

    The objectives of this study are to investigate thermal behavior of coal and biomass blends in inert gas environment at low heating rates and to develop a simplified kinetic model using model fitting techniques based on TGA experimental data. Differences in thermal behavior and reactivity in co-pyrolysis of Powder River Basin (PRB) sub-bituminous coal and pelletized southern yellow pine wood sawdust blends at low heating rates are observed. Coal/wood blends have higher reactivity compared to coal alone in the lower temperature due to the high volatile matter content of wood. As heating rates increase, weight loss rates increase. The experiment data obtained from TGA has a better fit with proposed two step first order reactions model compared single first order reaction model.

  7. Comparing kinetic profiles between bifunctional and binary type of Zn(salen-based catalysts for organic carbonate formation

    Directory of Open Access Journals (Sweden)

    Carmen Martín

    2014-08-01

    Full Text Available Zn(salen complexes have been employed as active catalysts for the formation of cyclic carbonates from epoxides and CO2. A series of kinetic experiments was carried out to obtain information about the mechanism for this process catalyzed by these complexes and in particular about the order-dependence in catalyst. A comparative analysis was done between the binary catalyst system Zn(salphen/NBu4I and a bifunctional system Zn(salpyr·MeI with a built-in nucleophile. The latter system demonstrates an apparent second-order dependence on the bifunctional catalyst concentration and thus follows a different, bimetallic mechanism as opposed to the binary catalyst that is connected with a first-order dependence on the catalyst concentration and a monometallic mechanism.

  8. A Comparative Study of Whitman and Frost

    Institute of Scientific and Technical Information of China (English)

    田寨耕

    2014-01-01

    Walt Whitman and Robert Frost are both famous poets in American literary history. They share a great deal in common. This paper attempts to make a study of the two poets by means of comparing their similarities and differences.

  9. A time-resolved study on the interaction of oppositely charged bicelles--implications on the charged lipid exchange kinetics.

    Science.gov (United States)

    Yang, Po-Wei; Lin, Tsang-Lang; Hu, Yuan; Jeng, U-Ser

    2015-03-21

    Time-resolved small-angle X-ray scattering was applied to study charged lipid exchange between oppositely charged disc-shaped bicelles. The exchange of charged lipids gradually reduces the surface charge density and weakens the electrostatic attraction between the oppositely charged bicelles which form alternately stacked aggregates upon mixing. Initially, at a high surface charge density with almost no free water layer between the stacked bicelles, fast exchange kinetics dominate the exchange process. At a later stage with a lower surface charge density and a larger water gap between the stacked bicelles, slow exchange kinetics take over. The fast exchange kinetics are correlated with the close contact of the bicelles when there is almost no free water layer between the tightly bound bicelles with a charged lipid exchange time constant as short as 20-40 min. When the water gap becomes large enough to have a free water layer between the stacked bicelles, the fast lipid exchange kinetics are taken over by slow lipid exchange kinetics with time constants around 200-300 min, which are comparable to the typical time constant of lipid exchange between vesicles in aqueous solution. These two kinds of exchange mode fit well with the lipid exchange models of transient hemifusion for the fast mode and monomer exchange for the slow mode.

  10. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    OpenAIRE

    Oana DUMITRASCU; Constantin Manuel HILA

    2014-01-01

    The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms...

  11. A Comparative Study on Error Analysis

    DEFF Research Database (Denmark)

    Wu, Xiaoli; Zhang, Chun

    2015-01-01

    Title: A Comparative Study on Error Analysis Subtitle: - Belgian (L1) and Danish (L1) learners’ use of Chinese (L2) comparative sentences in written production Xiaoli Wu, Chun Zhang Abstract: Making errors is an inevitable and necessary part of learning. The collection, classification and analysis...... the occurrence of errors either in linguistic or pedagogical terms. The purpose of the current study is to demonstrate the theoretical and practical relevance of error analysis approach in CFL by investigating two cases - (1) Belgian (L1) learners’ use of Chinese (L2) comparative sentences in written production....... Finally, pedagogical implication of CFL is discussed and future research is suggested. Keywords: error analysis, comparative sentences, comparative structure ‘‘bǐ - 比’, Chinese as a foreign language (CFL), written production...

  12. Chemical Oxidative Polymerization of 2-Aminothiazole in Aqueous Solution: Synthesis, Characterization and Kinetics Study

    Directory of Open Access Journals (Sweden)

    Hua Zou

    2016-11-01

    Full Text Available The chemical oxidative polymerization of 2-aminothiazole (AT was studied in aqueous solution using copper chloride (CuCl2 as an oxidant. The effect of varying the reaction temperature, reaction time and oxidant/monomer molar ratio on the polymer yield was investigated. The resulting poly(2-aminothiazoles (PATs were characterized by FTIR, 1H NMR, UV-vis, gel permeation chromatography, scanning electron microscopy, thermogravimetric analysis and four-point probe electrical conductivity measurements. Compared with a previous study, PATs with higher yield (81% and better thermal stability could be synthesized. The chemical oxidative polymerization kinetics of AT were studied for the first time. The orders of the polymerization reaction with respect to monomer concentration and oxidant concentration were found to be 1.14 and 0.97, respectively, and the apparent activation energy of the polymerization reaction was determined to be 21.57 kJ/mol.

  13. Study of Electron Acceleration and Multiple Dipolarization Fronts in 3D kinetic models

    Science.gov (United States)

    Lapenta, Giovanni; Ashour-Abdalla, Maha; Walker, Raymond; El-Alaoui, Mostafa

    2014-05-01

    The THEMIS mission encountered a depolarization front (DF) during a magnetotail crossing in the interval 035600 - 035900 UT on February 15, 2008 [1]. We present the results of an innovative investigative approach: we combine a global MHD model of the full Earth environment with a local PIC simulation. The global MHD view is provided on the UCLA model applied to the conditions for the interval of interest on Feb 15, 2008. At the specific time of 034800UT, a reconnection site first appear at about x=-15RE, y=4RE. We then use this specific MHD state as the initial setup for a fully kinetic PIC simulation, performed with the iPic3D code [2]. We consider a one way coupling where the MHD state is used as initial state and boundary conditions for the kinetic study [3]. In the present case, the time span of the kinetic simulation is short form the perspective of the global MHD simulation and does not require a full coupling where the MHD then process the information received back from the kinetic run [4]. The fields and particles are advanced self-consistently from the MHD state using a completely kinetic treatment. Many features missed by the MHD model emerge. Most notably a fast reconnection pattern develops and an unsteady reconnection process develops. The typical signatures of fast kinetic reconnection (Hall field) are observed and particle acceleration is obtained self consistently in the fields generated by the PIC simulation. The focus of the presentation will be the mechanisms of unsteady reconnection leading to multiple DFs. We observe intense wave activity propagating off the separatrices. We conduct a spectral analysis to isolate the different wave components in the lower hybrid and whistler regime. The unsteady reconnection and multiple DFs are also analysed in their impact on the energy transfer. We track the conversion of magnetic energy to particle energy and Poynting flux. The processes observed in the simulation are then compared with in situ THEMIS data

  14. Kinetic Studies on Na+/K+-ATPase by Using Thermokinetic Method

    Institute of Scientific and Technical Information of China (English)

    LI, Xia(李霞); LI, Jie(李杰); WANG, Zhi-Yong(王志勇); XIE, Xiu-Yin(谢修银); YANG, Xi(杨洗); WANG, Cun-Xin(汪存信)

    2004-01-01

    Na+/K+-ATPase (EC 3.6.1.3) is an important membrane-bound enzyme. By using microcalorimetry, the thermokinetic method was developed to kinetic studies on Na+/K+-ATPase for the first time. Compared with other ones, the method provided accurate measurements of not only thermodynamic data but also the kinetic data. At 310.15 K and pH=7.4, the molar reaction enthalpy ΔrHm was measured as (-40.408±1.9) kJ·mol-1. The Michaelis constant Km was determined to be (0.479±0.020)×10-3 mol·L-1 and consistent with literature figure which is about 0.5×10-3 mol·L-1. The maximum velocity Vmax obtained was (0.681±0.026) μmol Pi·min-1·mg protein-1. All of the data have good repeatability and self-consistency. The reliability of thermokinetic method was verified by the experimental results and further confirmed by colorimetric studies. Moreover, the effect of enzyme pre-dilution on its activities was also investigated.

  15. Optimization and Kinetic Studies on Biodiesel Production from Kusum (Schleichera triguga) Oil Using Response Surface Methodology.

    Science.gov (United States)

    Sarve, Antaram; Varma, Mahesh N; Sonawane, Shriram S

    2015-01-01

    In the present study, the low-cost non-edible kusum (Schleichera triguga) oil with a substantial amount of free fatty acid (FFA) was utilized for biodiesel synthesis. In pretreatment step, FFA was reduced by the acid catalyzed esterification method. Then, response surface method (RSM) in conjunction with centre composite design (CCD) containing 30 experimental runs were statistically employed for process optimization and kinetic study for the base catalyzed transesterification process. A statistical model predicted highest fatty acid methyl ester (FAME) yield of 97.37% at the optimal values of process parameters as follows: sodium methoxide concentration 0.9 wt% of oil, Methanol to oil molar ratio 9:1, temperature 58.9 ℃ and reaction time 58.5 min. Using these optimal parameters under experimental conditions in three independent replicates an actual FAME content of 98.14% was obtained which was in reasonable agreement with predicted one. The developed kinetic model suggested a 1.8(th) order reaction with activation energy of 31.42 kcal mol(-1) and frequency factor of 5.53×10(19) L mol(-1)min(-1). Furthermore, Important fuel properties of kusum oil biodiesel (KOB) was compared with ASTM 6751 and DIN EN 14214. The viscosity was found to be 5.34 Cst at 40 °C and the flash point was 152°C.

  16. Kinetic studies of lycopene isomerization in a tributyrin model system at gastric pH.

    Science.gov (United States)

    Moraru, Catalin; Lee, Tung-Ching

    2005-11-16

    A semi-preparative HPLC method was developed in order to isolate and purify the 13-cis-lycopene isomer in tomato-based materials. The result was compared with the naturally predominant all-trans-lycopene isomer, in terms of stability to gastric pH at physiological temperature in a tributyrin model system. Kinetic experiments confirmed that lycopene isomerization is a reversible reaction, and under these conditions the all-trans isomer is more stable than the 13-cis isomer. In addition, it was found that at gastric pH 13-cis-lycopene would predominantly isomerize to the all-trans form rather than undergo oxidation/breakdown. A simulation based on the rate constants calculated in the kinetic study indicated that at gastric pH the lycopene isomeric distribution aimed toward an equilibrium characterized by approx 16% 13-cis-, 16% 9-cis-, and 68% all-trans-lycopene. This study suggests that pH-driven isomerization in the stomach is at least partially responsible for the relatively high cis-lycopene proportion found in vivo.

  17. Comparative plasma disposition kinetics of albendazole and its new benzimidazol prodrug in dog.

    Science.gov (United States)

    Khalil, Z; El Karbane, M; Faouzi, M E A; Ansar, M; Azougagh, M; El Harti, J; Taoufik, J

    2016-01-01

    The comparative pharmacokinetic behavior of albendazole (ABZ) and its new benzimidazol prodrug [1-tert-butyloxycarbonyl-5-propylthio-1-H-benzimidazol-2ylcarbamate of methyl] (ABZBoc), following their oral administration (10mg/kg) to healthy dogs was explored. Blood samples were obtained serially over a 24h period after treatment, then the plasma was analyzed by high-performance liquid chromatography (HPLC) to search the albendazole metabolites (ABZSO and ABZSO2). However, the albendazole parent drug was not detectable at any time after both treatments (ABZ and ABZBoc). By albendazole metabolites (ABZSO and ABZSO2) were the analytes recovered in the plasma after oral administration of ABZ and ABZBoc. Furthermore, some amounts of ABZBoc were also available in the plasma samples treated with this new produg. The plasma profile of each analyte followed a similar pattern after both treatments, the active metabolite (ABZSO) was the major analyte recovered in plasma (between 1 and 24h post-treatment). The pharmacokinetic parameters of both groups were calculated (Cmax, Tmax, t1/2, AUC0-›∞), and analyzed using the Student's t-test, Palbendazole metabolites (ABZSO, ABZSO2) between the group treated with albendazole (group A) and that treated with ABZBoc prodrug (group B). Hence, the levels of the various pharmacokinetics parameters were low in the group treated with prodrug, as well they did not reach equivalent concentrations to that of albendazole. These differences between albendazole and its new prodrug may be explained by the fact that ABZBoc prodrug was not effectively reduced in the intestine of dogs.

  18. Comparing Poynting flux dominated magnetic tower jets with kinetic-energy dominated jets

    CERN Document Server

    Huarte-Espinosa, Martín; Blackman, Eric G; Ciardi, Andrea; Hartigan, Patrick M; Lebedev, Sergey; Chittenden, Jeremy P

    2012-01-01

    Magnetic Towers represent one of two fundamental forms of MHD outflows. Driven by magnetic pressure gradients, these flows have been less well studied than magneto-centrifugally launched jets even though magnetic towers may well be as common. Here we present new results exploring the behavior and evolution of magnetic tower outflows and demonstrate their connection with pulsed power experimental studies and purely hydrodynamic jets which might represent the asymptotic propagation regimes of magneto-centrifugally launched jets. High-resolution AMR MHD simulations (using the AstroBEAR code) provide insights into the underlying physics of magnetic towers and help us constrain models of their propagation. Our simulations have been designed to explore the effects of thermal energy losses and rotation on both tower flows and their hydro counterparts. We find these parameters have significant effects on the stability of magnetic towers, but mild effects on the stability of hydro jets. Current-driven perturbations in...

  19. Kinetic study of olive oil degradation monitored by fourier transform infrared spectrometry. Application to oil characterization.

    Science.gov (United States)

    Román Falcó, Iván P; Grané Teruel, Nuria; Prats Moya, Soledad; Martín Carratalá, M Luisa

    2012-11-28

    A new approach for the determination of kinetic parameters of the cis/trans isomerization during the oxidation process of 24 virgin olive oils belonging to 8 different varieties is presented. The accelerated process of degradation at 100 °C was monitored by recording the Fourier transform infrared spectra. The parameters obtained confirm pseudo-first-order kinetics for the degradation of cis and the appearance of trans double bonds. The kinetic approach affords the induction time and the rate coefficient; these parameters are related to the fatty acid profile of the fresh olive oils. The data obtained were used to compare the oil stability of the samples with the help of multivariate statistical techniques. Fatty acid allowed a classification of the samples in five groups, one of them constituted by the cultivars with higher stability. Meanwhile, the kinetic parameters showed greater ability for the characterization of olive oils, allowing the classification in seven groups.

  20. Kinetic study of rigid polyurethane foams thermal decomposition by artificial neural network

    CERN Document Server

    Ferreira, Bárbara D L; Yoshida, Maria Irene; Sebastião, Rita C O

    2016-01-01

    Kinetic models of solid thermal decomposition are traditionally used for individual fit of isothermal decomposition experimental data. However, this methodology can provide unacceptable errors in some cases. To solve this problem, a neural network (MLP) was developed and adopted in this work. The implemented algorithm uses the rate constants as predetermined weights between the input and intermediate layer and kinetic models as activation functions of neurons in the hidden layer. The contribution of each model in the overall fit of the experimental data is calculated as the weights between the intermediate and output layer. In this way, the phenomenon is better described as a sum of kinetic processes. Two rigid polyurethane foam samples: loaded with Al2O3 and no inorganic filler were used in this work. The R3 model described the thermal decomposition kinetic process for all temperatures for both foams with smaller residual error. However, the network residual errors are on average 102 times lower compared to ...

  1. Adsorption of crystal violet onto functionalised multi-walled carbon nanotubes: Equilibrium and kinetic studies.

    Science.gov (United States)

    Sabna, V; Thampi, Santosh G; Chandrakaran, S

    2016-12-01

    Synthetic dyes present in effluent from textile, paper and paint industries contain crystal violet (CV), a known carcinogenic agent. This study investigates the modification of multiwalled carbon nanotubes by acid reflux method and equilibrium and kinetic behaviour of adsorption of CV onto functionalized multi-walled carbon nanotubes (fMWNTs) in batch system. High stability of the fMWNTs suspension in water indicates the hydrophilicity of fMWNTs induced due to the formation of functional groups that make hydrogen bonds with water molecules. fMWNTs were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and the functional groups present on the fMWNTs were confirmed. Characteristic variation was observed in the FTIR spectra of fMWNTs after adsorption of crystal violet onto it. Adsorption characteristics were evaluated as a function of system variables such as contact time, dosage of fMWNTs and initial concentration and pH of the crystal violet solution. Adsorption capacity of fMWNTs and percentage removal of the dye increased with increase in contact time, adsorbent dosage and pH but declined with increase in initial concentration of the dye. fMWNTs showed higher adsorption capacity compared to that of pristine MWNTs. Data showed good fit with the Langmuir and Freundlich isotherm models and the pseudo-second order kinetic model; the maximum adsorption capacity was 90.52mg/g. Kinetic parameters such as rate constants, equilibrium adsorption capacities and regression coefficients were estimated. Results indicate that fMWNTs are an effective adsorbent for the removal of crystal violet from aqueous solution.

  2. Kinetic study of oil extraction from olive foot cake

    Directory of Open Access Journals (Sweden)

    Lamrous, O.

    2006-06-01

    Full Text Available The kinetics of oil extraction from olive foot cake can be explained by a model based on two stages. The first step corresponds to a simple washing of the oil from the particle surface. In the second step, the extraction is controlled by two mechanisms: slow diffusion from broken cells and very slow diffusion from intact cells.The kinetic coefficients of this mathematical model are calculated using the experimental results obtained from hexane and commercial ethyl alcohol for different particle sizes.La cinética de extracción de aceite de orujo puede ser explicada por un modelo basado en dos etapas. La primera etapa corresponde a un simple lavado del aceite de la superficie de las partículas. En la segunda etapa, la extracción esta controlada por dos mecanismos: difusión lenta desde las células rotas y difusión muy lenta desde las células intactas.Los coeficientes cinéticas de este modelo matemático se calculan usando los resultados experimentales obtenidos con hexano y alcohol etílico comercial para diferentes tamaños de partícula.

  3. A thermoanalytic and kinetic study of sunflower oil

    Directory of Open Access Journals (Sweden)

    Souza A. Gouveia de

    2004-01-01

    Full Text Available Recently, thermoanalytic methods have frequently been used in the characterization of oils and fats. In this work, thermoanalytic and kinetic parameters of sunflower oils, with and without antioxidants, were evaluated using thermogravimetry / derivative thermogravimetry and differential scanning calorimetry. The thermogravimetric profiles for the sunflower oils had similar characteristics, showing a level stretch indicative of stability up to about 200ºC. Thermal decomposition of these oils occurred in three stages, related to the decomposition of polyunsaturated, monounsaturated and saturated fatty acids, respectively. DSC curves show two events that characterize the polymerization and decomposition of triglycerides. The heat capacities of the sunflower oils, obtained by DSC, showed a good correlation and were dependent on the composition of fatty acids. The kinetic parameters, obtained by non isothermal thermogravimetry by the Coats and Redfern, Madhusudanan, Horowitz and Metzger and Van Krevelen methods, were dependent on the antioxidant used. Increasing the frying time produced a decrease in the onset of thermal decomposition temperature in the sunflower oils analyzed.

  4. Mathematics education and comparative historical studies

    Directory of Open Access Journals (Sweden)

    Wagner RODRIGUES VALENTE

    2013-11-01

    Full Text Available This paper has as its aims: to characterize the area of research «history of mathematics education» and to defend the idea that mathematics education has constituted a privileged research theme within the field of comparative historical studies. To achieve these aims, the text includes references to a review of the literature concerning comparative studies, the analysis of two fundamental moments focused on attempts to internationalize the mathematics curriculum, both of which occurred during the 20th century, and, to end, a case study emanating from an international cooperation between researchers in Brazil and Portugal.

  5. Magnetotactic bacteria and microjets: A comparative study

    NARCIS (Netherlands)

    Khalil, I.S.M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver G.; Misra, Sarthak

    2013-01-01

    We provide a comparative study between two self-propelled microrobots, i.e., magnetotactic bacteria and microjets. This study includes characterization of their fluidic properties (linear and rotational drag coefficients) based on their morphologies and characterization of their magnetic properties

  6. Study on the Kinetics of Aluminum Removal from Liquid Silicon to Slag with Mechanical Stirring

    Science.gov (United States)

    Lee, Jaewoo; White, Jesse F.; Hildal, Kjetil; Sichen, Du

    2016-12-01

    The kinetics of aluminum removal from silicon melt to CaO-SiO2-Al2O3 slag was studied. A recently designed experimental setup using mechanical stirring was employed to focus the study on the chemical reaction. The slag and metal were found to reach chemical equilibrium in 300 seconds. A simple model could reproduce the experimental data satisfactorily. Both the experimental results and the model prediction further confirmed that the process was controlled by the chemical reaction, since the reaction rate constant was found to be independent of the amount of slag and the initial slag composition. The experimental data at equilibrium were compared with the model calculations. The discrepancy between the model calculations and the experimental data strongly suggests the need for careful thermodynamic measurements.

  7. Studies on Enzyme Kinetics by Microchip and Related Techniques

    Institute of Scientific and Technical Information of China (English)

    James J. Bao; WANG Huai-Feng; ZHOU Da-Wei; Ken R. Wehmeyer

    2004-01-01

    Both conventional and microchip-based capillary electrophoresis(CE) technologies have been used for the analysis of enzymes. Practical procedures of using CE to determine the Km and Vmax values of an enzyme have been developed. By studying the inhibition to the enzyme, it is possible to select a suitable drug candidate. When compared with the conventional CE method, single lane microchip-based method can improve the speed for the assay three times. By using multiple lane-based microchip, the speed can be further increased.

  8. A COMPARATIVE STUDY OF BYG SEARCH ENGINES

    Directory of Open Access Journals (Sweden)

    Kailash Kumar

    2013-01-01

    Full Text Available This paper compares the retrieval effectiveness of the Bing, Yahoo and Google (BYG Search Engines. The precision and relative recall of each search engine was considered for evaluating the effectiveness of the search engines. General Queries were tested. Results of the study showed that the precision of Google was high as compared to other two search engines and Yahoo has better precision than Bing

  9. Experimental and numerical studies of burning velocities and kinetic modeling for practical and surrogate fuels

    Science.gov (United States)

    Zhao, Zhenwei

    To help understand the fuel oxidation process in practical combustion environments, laminar flame speeds and high temperature chemical kinetic models were studied for several practical fuels and "surrogate" fuels, such as propane, dimethyl ether (DME), and primary reference fuel (PRF) mixtures, gasoline and n-decane. The PIV system developed for the present work is described. The general principles for PIV measurements are outlined and the specific considerations are also reported. Laminar flame speeds were determined for propane/air over a range of equivalence ratios at initial temperature of 298 K, 500 K and 650 K and atmospheric pressure. Several data sets for propane/air laminar flame speeds with N 2 dilution are also reported. These results are compared to the literature data collected at the same conditions. The propane flame speed is also numerically calculated with a detailed kinetic model and multi component diffusion, including Soret effects. This thesis also presents experimentally determined laminar flame speeds for primary reference fuel (PRF) mixtures of n-heptane/iso-octane and real gasoline fuel at different initial temperature and at atmospheric pressure. Nitrogen dilution effects on the laminar flame speed are also studied for selected equivalence ratios at the same conditions. A minimization of detailed kinetic model for PRF mixtures on laminar flame speed conditions was performed and the measured flame speeds were compared with numerical predictions using this model. The measured laminar flame speeds of n-decane/air mixtures at 500 K and at atmospheric pressure with and without dilution were determined. The measured flame speeds are significantly different that those predicted using existing published kinetic models, including a model validated previously against high temperature data from flow reactor, jet-stirred reactor, shock tube ignition delay, and burner stabilized flame experiments. A significant update of this model is described which

  10. Effects of penconazole on two yeast strains: growth kinetics and molecular studies.

    Science.gov (United States)

    Jawich, Dalal; Lteif, Roger; Pfohl-Leszkowicz, Annie; Strehaiano, Pierre

    2006-05-01

    The aim of this study consisted to evaluate the impact of a pesticide (penconazole) on the growth kinetics and genotoxicity on two yeast strains (Saccharomyces cerevisiae and Metschnikowia pulcherrima). When the penconazole was added at different phases of the growth of M. pulcherrima, no effect was noticed on the kinetics of yeast growth but DNA adducts were observed when penconazole was added in the exponential phase. Increasing doses (1-15 maximum residue limit) of the pesticide added at the beginning of the fermentation did not induce DNA adducts while kinetics were affected.

  11. Application of Thermogravimetry to Study the Kinetics and Stability of Porphyrin Copper-sodium of Ephedra

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Thermogravimetry was used to study the non-isothermal decomposition kinetics and the stability of porphyrin copper-sodium from ephedra. The kinetic equation for the second step can be expressed as dα/(dT)=Ae-(Eα)/(RT)3/2(1-α)4/3/[(1-α)-1/3-1]. The kinetic compensation effect is found to be: lnA=0.2468Ea-8.0513. Ea is 206.61 kJ/mol. The results show that porphyrin copper-sodium has a high activation energy and good stability.

  12. Pyrolysis kinetics study of three biomass solid wastes for thermochemical conversion into liquid fuels

    Science.gov (United States)

    Tuly, S. S.; Parveen, M.; Islam, M. R.; Rahman, M. S.; Haniu, H.

    2017-06-01

    Pyrolysis has been considered as the most efficient way of producing liquid fuel from biomass and its wastes. In this study the thermal degradation characteristics and pyrolysis kinetics of three selected biomass samples of Jute stick (Corchorus capsularis), Japanese cedar wood (Cryptomeria japonica) and Tamarind seed (Tamarindus indica) have been investigated in a nitrogen atmosphere at heating rates of 10°C/min and 60°C/min over a temperature range of 30°C to 800°C. The weight loss region for the three biomass solid wastes has shifted to a higher temperature range and the weight loss rate has increased with increasing heating rate. In this case, the three biomass samples have represented the similar behavior. The initial reaction temperature has decreased with increasing heating rate but the reaction range and reaction rate have increased. The percentage of total weight loss is higher for cedar wood than jute stick and tamarind seed. For the three biomass wastes, the overall rate equation has been modeled properly by one simplified equation and from here it is possible to determine kinetic parameters of unreacted materials based on Arrhenious form. The calculated rate equation compares thoroughly well with the measured TG and DTG data.

  13. Microwave assisted synthesis and optimization of Aegle marmelos-g-poly(acrylamide): release kinetics studies.

    Science.gov (United States)

    Setia, A; Kumar, R

    2014-04-01

    Microwave assisted grafting of poly(acrylamide) on to Aegle marmelos gum was carried out employing 3-factor 3-level full factorial design. Microwave power, microwave exposure time and concentration of gum were selected as independent variable and grafting efficiency was taken as dependent variable. A. marmelos-g-poly(acrylamide) was characterized by FTIR, DSC, X-ray diffraction and scanning electron microscopy. Microwave power, microwave exposure time had synergistic effect on grafting efficiency where as concentration of the gum did not contributed much to grafting efficiency. Batch having microwave power - 80%, microwave exposure time -120 s and concentration of A. marmelos gum - 2% was selected as the optimized formulation. Comparative release behaviour of diclofenac sodium from the matrix tablets of A. marmelos gum and A. marmelos-g-polyacrylamide was evaluated. The results of kinetic studies revealed that the graft copolymer matrix, marketed tablets and polymer matrix tablets of A. marmelos gum released the drug by zero order kinetics and with n value greater than 1, indicating that the mechanism for release as super case II transport i.e. dominated by the erosion and swelling of the polymer.

  14. Kinetic study of the catalytic pyrolysis of elephant grass using Ti-MCM-41

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, Maria do Socorro Braga; Melo, Dulce Maria de Araujo; Rodrigues, Glicelia, E-mail: socorro.fontes@yahoo.com.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Barros, Joana Maria de Farias [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Dept. de Quimica; Braga, Renata Martins [Universidade Federal da Paraiba (UFPB/CEAR/DEER), Joao Pessoa, PB (Brazil). Centro de Energias Alternativas e Renovaveis. Dept. de Engenharia de Energia Renovaveis

    2014-08-15

    This work aimed to study the kinetics of thermal and catalytic pyrolysis using Ti-MCM-41 as catalyst in order to assess the catalytic pyrolysis efficiency compared to thermal pyrolysis of elephant grass. Ti-MCM-41 molecular sieve was synthesized by hydrothermal method from hydrogel with the following molar composition: 1.00 CTMABr: 4.00 SiO{sub 2}:X TiO{sub 2}: 1 + X Na{sub 2}O: 200.00 H{sub 2}O, which structure template used was cetyltrimethylammonium bromide (CTMABr). The materials synthesized were characterized by X-ray diffraction, IR spectroscopy, thermogravimetric analysis and specific area by the BET method, for subsequent application in the biomass pyrolysis process. The kinetic models proposed by Vyazovkin and Flynn-Wall were used to determine the apparent activation energy involved in the thermal and catalytic pyrolysis of elephant grass and the results showed that the catalyst used was effective in reducing the apparent activation energy involved in the thermal decomposition of elephant grass. (author)

  15. Isotherm, thermodynamic, kinetics and adsorption mechanism studies of methyl orange by surfactant modified silkworm exuviae

    Energy Technology Data Exchange (ETDEWEB)

    Chen Hao, E-mail: chenhao2212@sohu.com [School of Pharmaceutical and Chemical Engineering, Taizhou University, Dongfang Road No. 605, Linhai 317000, Zhejiang (China); Zhao Jie; Wu Junyong; Dai Guoliang [School of Pharmaceutical and Chemical Engineering, Taizhou University, Dongfang Road No. 605, Linhai 317000, Zhejiang (China)

    2011-08-15

    This paper reports on the development of organo-modified silkworm exuviae (MSE) adsorbent prepared by using hexadecyltrimethylammonium bromide (HDTMAB) for removing methyl orange (MO), a model anionic dye, from aqueous solution. The natural and modified samples were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FT-IR). Batch adsorption experiments were carried out to remove MO from its aqueous solutions using SE and MSE. It was observed that the adsorption capacity of MSE is 5-6 times of SE. The different parameters effecting on the adsorption capacity such as pH of the solution, initial dye concentration, temperature and contact time have been investigated. Analysis of adsorption results obtained at different temperatures showed that the adsorption pattern on the MSE can be described perfectly with Langmuir isotherm model compared with Freundlich and Dubinin-Radushkevich (D-R) isotherm models, and the characteristic parameters for each adsorption isotherm were also determined. The adsorption process has been found exothermic in nature and thermodynamic parameters have been calculated. The adsorption kinetic followed the pseudo-second order kinetic model. The results of FT-IR, EDS and desorption studies all suggest that methyl orange adsorption onto the MSE should be mainly controlled by the hydrophobic interaction mechanism, along with a considerable contribution of the anionic exchange mechanism. The results indicate that HDTMAB-modified silkworm exuviae could be employed as low-cost material for the removal of methyl orange anionic dye from wastewater.

  16. KINETIC AND THERMODYNAMIC STUDY ON ADSORPTION BY STARCHY MATERIALS IN THE ETHANOL-WATER SYSTEM

    Directory of Open Access Journals (Sweden)

    M.J. Carmo

    1997-09-01

    Full Text Available Improving adsorptive processes demands a constant search for new adsorbents. In the specific case of ethanol-water separation, A zeolites are successfully being used. The use of nonconventional adsorbents to substitute zeolites, mainly starchy adsorbents in virtue of their known chemical affinity water, has recently been proposed. In this work a thermodynamic and kinetic study has been undertaken on the liquid phase adsorption of water from an ethanol-water mixture using manioc starch pellets as the adsorbent. The fundamental thermodynamic data were obtained by means of the static method, using a thermostated bath at four different temperatures (25, 40, 50 and 60° C, and could be correlated by means of a semi-empirical isotherm. The kinetic data, in turn, were obtained in a finite circulating liquid bath cell, enabling the construction of uptake rate curves, whereby the influence of temperature, interstitial velocity and adsorbent mean particle size on the adsorption rate was analyzed. The effective internal diffusivities at the experimental temperatures were estimated by a pore diffusion model and the results obtained were compared with those for commercial 3A zeolite

  17. Isotherm, thermodynamic, kinetics and adsorption mechanism studies of methyl orange by surfactant modified silkworm exuviae.

    Science.gov (United States)

    Chen, Hao; Zhao, Jie; Wu, Junyong; Dai, Guoliang

    2011-08-15

    This paper reports on the development of organo-modified silkworm exuviae (MSE) adsorbent prepared by using hexadecyltrimethylammonium bromide (HDTMAB) for removing methyl orange (MO), a model anionic dye, from aqueous solution. The natural and modified samples were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FT-IR). Batch adsorption experiments were carried out to remove MO from its aqueous solutions using SE and MSE. It was observed that the adsorption capacity of MSE is 5-6 times of SE. The different parameters effecting on the adsorption capacity such as pH of the solution, initial dye concentration, temperature and contact time have been investigated. Analysis of adsorption results obtained at different temperatures showed that the adsorption pattern on the MSE can be described perfectly with Langmuir isotherm model compared with Freundlich and Dubinin-Radushkevich (D-R) isotherm models, and the characteristic parameters for each adsorption isotherm were also determined. The adsorption process has been found exothermic in nature and thermodynamic parameters have been calculated. The adsorption kinetic followed the pseudo-second order kinetic model. The results of FT-IR, EDS and desorption studies all suggest that methyl orange adsorption onto the MSE should be mainly controlled by the hydrophobic interaction mechanism, along with a considerable contribution of the anionic exchange mechanism. The results indicate that HDTMAB-modified silkworm exuviae could be employed as low-cost material for the removal of methyl orange anionic dye from wastewater.

  18. Experimental and kinetic studies for phycoremediation and dye removal by Chlorella pyrenoidosa from textile wastewater.

    Science.gov (United States)

    Pathak, Vinayak V; Kothari, Richa; Chopra, A K; Singh, D P

    2015-11-01

    Potential of Chlorella pyrenoidosa was experimentally investigated for phycoremediation and dye removal from textile wastewater (TWW) in batch cultures. Growth of alga was observed at various concentration of textile wastewater (25%, 50%, 75% and 100%) and was found in a range of 8.1-14 μg ml(-1) day(-1). Growth study revealed that alga potentially grows up to 75% concentrated textile wastewater and reduces phosphate, nitrate and BOD by 87%, 82% and 63% respectively. Methylene blue dye (MB) removal was also observed by using dry and wet algal biomass harvested after phycoremediation. Adsorption isotherms (Langmuir and Freundlich) and kinetic models (pseudo first and second order) were applied on adsorption process. Dry algal biomass (DAB) was found more efficient biosorbent with large surface area and showed high binding affinity for MB dye in compare to wet algal biomass (WAB). The RL value for both biosorbent showed feasible adsorption process as the obtained value was between 0 and 1. Pseudo second order kinetic model with high degree of correlation coefficient and low sum of error squares (SSE %) value was found more suitable for representation of adsorption process in case of both biosorbents, however pseudo first order also showed high degree of correlation for both biosorbents.

  19. Fabrication and kinetics study of nano-Al/NiO thermite film by electrophoretic deposition.

    Science.gov (United States)

    Zhang, Daixiong; Li, Xueming

    2015-05-21

    Nano-Al/NiO thermites were successfully prepared as film by electrophoretic deposition (EPD). For the key issue of this EPD, a mixture solvent of ethanol-acetylacetone (1:1 in volume) containing 0.00025 M nitric acid was proved to be a suitable dispersion system for EPD. The kinetics of electrophoretic deposition for both nano-Al and nano-NiO were investigated; the linear relation between deposition weight and deposition time in short time and parabolic relation in prolonged time were observed in both EPDs. The critical transition time between linear deposition kinetics and parabolic deposition kinetics for nano-Al and nano-NiO were 20 and 10 min, respectively. The theoretical calculation of the kinetics of electrophoretic deposition revealed that the equivalence ratio of nano-Al/NiO thermites film would be affected by the behavior of electrophoretic deposition for nano-Al and nano-NiO. The equivalence ratio remained steady when the linear deposition kinetics dominated for both nano-Al and nano-NiO. The equivalence ratio would change with deposition time when deposition kinetics for nano-NiO changed into parabolic kinetics dominated after 10 min. Therefore, the rule was suggested to be suitable for other EPD of bicomposites. We also studied thermodynamic properties of electrophoretic nano-Al/NiO thermites film as well as combustion performance.

  20. Ignition characteristics of 2-methyltetrahydrofuran: An experimental and kinetic study

    KAUST Repository

    Tripathi, Rupali

    2016-10-15

    The present paper elucidates oxidation behavior of 2-methyltetrahydrofuran (2-MTHF), a novel second-generation biofuel. New experimental data sets for 2-MTHF including ignition delay time measurements in two different combustion reactors, i.e. rapid compression machine and high-pressure shock tube, are presented. Measurements for 2-MTHF/oxidizer/diluent mixtures were performed in the temperature range of . 639-1413 K, at pressures of 10, 20, and 40 bar, and at three different equivalence ratios of 0.5, 1.0, and 2.0. A detailed chemical kinetic model describing both low-and high-temperature chemistry of 2-MTHF was developed and validated against new ignition delay measurements and already existing flame species profiles and ignition delay measurements. The mechanism provides satisfactory agreement with the experimental data. For identifying key reactions at various combustion conditions and to attain a better understanding of the combustion behavior, reaction path and sensitivity analyses were performed.

  1. Substituent effects of iron porphyrins: Structural, kinetic, and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xiaoquan, E-mail: luxq@nwnu.edu.c [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070 (China); Ma Junying; Sun Ruiping; Nan Mina; Meng Fanfu; Du Jie; Wang Xiaoyan; Shang Hui [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070 (China)

    2010-12-15

    Substituent effects of iron porphyrin complexes on the structures and kinetic processes have been examined for the first time. Basing on the premise that iron porphyrin is functional analogous to heme, a series of iron porphyrin derivatives bearing different substituents at the meso positions of the corrole ring are investigated as to their electrochemistry, the relationships among the electron transfer (ET) processes, their structures, and orbital energies. The good coherence between the experiment and theory indicates that the ET rate can be accelerated when electron-donating substituents are introduced to the iron porphyrin ring. Finally, the implications of the results are discussed in the influence of stability of iron porphyrin complexes on the ability to carry molecular oxygen, which may suggest it possible to dominate the biological activity of heme by selecting the appropriate substituents to iron porphyrin ring.

  2. Study on the comprehensive combustion kinetics of MSW

    Institute of Scientific and Technical Information of China (English)

    金余其; 严建华; 岑可法

    2004-01-01

    The combustion behavior of typical components of MSW was examined with a thermal gravimetric analyzer (TGA). The experiments were done over the temperature range of room temperature to 1000℃ at a heating rate of 10 oC/min and in an oxidizing atmosphere. The results indicated that the entire weight loss process of each typical component of MSW consists of one to three distinct combustion stages. The combustion of typical components of MSW could be modeled by one to three independent reactions. The corresponding parameters of typical components of MSW such as activation energy, pre-exponential factor, and reaction order were determined. The calculated results using the comprehensive kinetic model composed of one to three independent and consecutive reactions, agreed well with experimental results.

  3. Kinetic Studies on Ni-YSZ Composite Electrodes

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Hjelm, Johan; Graves, Christopher R.

    2015-01-01

    . Furthermore, when polarized, the cell heats up due to joule heating of the electrolyte but also the electrodes either heat or cool due to exothermic oxidation or endothermic reduction of gaseous reactant species. Kinetic investigation of SOC electrodes independent of the above effects thus requires...... transfer at the reaction sites gas conversion at the flow fields, and ohmic drop across the electrolyte. Since these processes occur in both electrodes and some of them with overlapping characteristic frequencies, it is particularly challenging to isolate and characterize a particular mechanism...... compositions using the same instrument. The tests are carried out in a single gas atmosphere with maximum flow rate of 6 L/h. Results and Discussion Current density vs working electrode overpotential curves recorded in the temperature range 800 – 650°C in a 50/50 H2/H2O fuel mixture are displayed in figure 1(a...

  4. Differential scanning calorimetry and reaction kinetics studies of {gamma} + {alpha}{sub 2} Ti aluminide

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.K., E-mail: rohitkumar_gupta@vssc.gov.in [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Pant, Bhanu [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India); Agarwala, Vijaya [Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Sinha, P.P. [Vikram Sarabhai Space Centre, ISRO, Trivandrum 695 022 (India)

    2012-12-14

    Reaction synthesis method for titanium aluminide processing consists of an exothermic reaction among alloying elements present and primarily between titanium and aluminium particles at specific temperature range. Study of this reaction helps in understanding the process of aluminide formation. Differential scanning calorimetry (DSC) study is the suitable method to study such reactions. In the present work, five different alloy mixtures based on Ti48Al2Cr2Nb0.1B are prepared and DSC study is carried out. Onset temperature, peak temperature and completion temperature of the major exothermic reaction is analyzed at different heating rates. Further, kinetics of the reaction is studied using Johnson-Mehl-Avrami equation. Activation energy and Avrami parameter are calculated and compared with the reported works on binary alloy. It has been observed that exothermic reaction is triggered by melting of aluminium. Boron assists in increasing the enthalpy of reaction by boride formation. Primary reaction product is found to be TiAl{sub 3}. Activation energy as well as Avrami parameter is found to have marginal variation due to small change in alloying elements in different alloys and due to heating rates in the same alloy. -- Highlights: Black-Right-Pointing-Pointer Reaction kinetics studies of Ti-aluminide alloy powder mixtures carried out. Black-Right-Pointing-Pointer Five compositions studied through non-isothermal differential scanning calorimetry. Black-Right-Pointing-Pointer Effect of minor boron addition and role of Ti particle size is noted. Black-Right-Pointing-Pointer Activation energies using JMA equations are between 169.5 and 192.49 kJ mol{sup -1}.

  5. Flow-Based Systems for Rapid and High-Precision Enzyme Kinetics Studies

    Directory of Open Access Journals (Sweden)

    Supaporn Kradtap Hartwell

    2012-01-01

    Full Text Available Enzyme kinetics studies normally focus on the initial rate of enzymatic reaction. However, the manual operation of steps of the conventional enzyme kinetics method has some drawbacks. Errors can result from the imprecise time control and time necessary for manual changing the reaction cuvettes into and out of the detector. By using the automatic flow-based analytical systems, enzyme kinetics studies can be carried out at real-time initial rate avoiding the potential errors inherent in manual operation. Flow-based systems have been developed to provide rapid, low-volume, and high-precision analyses that effectively replace the many tedious and high volume requirements of conventional wet chemistry analyses. This article presents various arrangements of flow-based techniques and their potential use in future enzyme kinetics applications.

  6. A thermodynamic and kinetic study of hydride transfer of a caffeine derivative.

    Science.gov (United States)

    Han, Xiaozhen; Hao, Weifang; Zhu, Xiao-Qing; Parker, Vernon D

    2012-08-03

    One representative type of heterocyclic compound that can release a hydride ion is 7,8-dihydro-9-methylcaffeine (CAFH). The one-electron oxidation potential of CAFH [-0.294 (V vs Fc(+/0))] and the one-electron reduction potential of CAF(+) [-2.120 (V vs Fc(+/0))] were obtained using two different methods, CV and OSWV. Applying titration calorimetry data in thermodynamic cycles, the enthalpies of CAFH releasing a hydride ion [57.6 kcal/mol] and releasing a hydrogen atom [80.3 kcal/mol] and of its radical cation CAFH(•+) releasing a proton [33.0 kcal/mol] and releasing a hydrogen atom [38.4 kcal/mol] have been determined. Several conclusions can be drawn from the thermodynamic results: (1) CAFH is a very good single-electron donor whose single-electron oxidation potential is much less positive than that of NAD(P)H model compound BNAH [E(ox) = 0.219 V vs Fc(+/0)]. (2) The single-electron reduction potential of CAF(+) is much more negative than that of BNA(+) [E(red) = -1.419 V], which means that CAF(+) is not a good electron acceptor. Furthermore, CAFH is a very good hydride donor compared to BNAH. The results of non-steady-state kinetic studies, for the reaction of CAFH and AcrH(+)ClO(4)(-), show that the ratio of t(0.50)/t(0.05) is larger than 13.5 and the ratio of k(init)/k(pfo) is larger than 1. The pseudo-first-order rate constants obtained at different reaction stages decrease with the time, and the kinetic isotope was observed to be small at a short reaction time and slowly increases to 3.72 with the progress of the reaction. These kinetic results clearly display that the hydride transfer of CAFH to AcrH(+) in acetonitrile is not a one-step mechanism, while the thermodynamic results show that CAFH is a very good electron donor. The combination of the kinetic results with the thermodynamics analysis shows that the hydride transfer of the caffeine derivative CAFH takes place by a two-step reversible mechanism and there is an intermediate in the reaction.

  7. A comparative study on two explosive acetone peroxides

    Energy Technology Data Exchange (ETDEWEB)

    Egorshev, V. Yu.; Sinditskii, V.P., E-mail: vps@rctu.ru; Smirnov, S.P.

    2013-12-20

    Highlights: • The most accurate heats of DADP and TATP sublimation were evaluated from experimental vapor pressures in a widened temperature range. • DADP is more volatile while more thermally stable peroxide than TATP. • DADP reveals lesser sensitivity to drop-weight impact, flame temperature, burning rate, and initiating efficiency as compared with TATP. - Abstract: Two explosive cyclic acetone peroxides, diacetone diperoxide (DADP) and triacetone triperoxide (TATP) have been studied in respect of thermal decomposition, burning behavior, impact sensitivity, and initiating efficiency. Using the glass Bourdon gauge technique, the vapor pressures of TATP and DADP were determined over the temperature range 75–144 °C and 67–120 °C, respectively. The kinetic parameters of decomposition of the peroxides in the gas phase have been obtained in the temperature interval of 140–200 °C. The decomposition of both DADP and TATP followed the first-order reaction to high degrees of decay with close activation energies of 159.2 kJ/mol (38.0 kcal/mol) and 165.8 kJ/mol (39.6 kcal/mol), respectively. The decomposition rate constants of DADP were found to be approximately 2 times less than those of TATP. The linear burning rate of DADP measured in a constant-pressure window bomb appeared to be approximately 5 times less than that of TATP. Temperature profiles in the combustion wave were measured at subatmospheric pressures with the help of thin tungsten-rhenium thermocouples. The leading reaction on combustion of both volatile peroxides was assumed to occur in the gas phase. Kinetic parameters of the leading reaction derived from the combustion data showed a good agreement with kinetic parameters of low-temperature thermal decomposition extrapolated to the high-temperature flame zone. In the drop-weight impact test, DADP appeared to be notably less sensitive peroxide than TATP. No deflagration-to-detonation transition was observed when RDX was attempted to explode by

  8. Species comparative studies and cognitive development.

    Science.gov (United States)

    Gómez, Juan-Carlos

    2005-03-01

    The comparative study of infant development and animal cognition brings to cognitive science the promise of insights into the nature and origins of cognitive skills. In this article, I review a recent wave of comparative studies conducted with similar methodologies and similar theoretical frameworks on how two core components of human cognition--object permanence and gaze following--develop in different species. These comparative findings call for an integration of current competing accounts of developmental change. They further suggest that evolution has produced developmental devices capable at the same time of preserving core adaptive components, and opening themselves up to further adaptive change, not only in interaction with the external environment, but also in interaction with other co-developing cognitive systems.

  9. Comparative study of quantum anharmonic potentials

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico)]. E-mail: paolo@ucol.mx; Aranda, Alfredo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima (Mexico); De Pace, Arturo [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via P. Giuria 1, I-10125 Torino (Italy); Lopez, Jorge A. [Physics Department, University of Texas at El Paso, El Paso, TX (United States)

    2004-09-06

    We perform a study of various anharmonic potentials using a recently developed method. We calculate both the wave functions and the energy eigenvalues for the ground and first excited states of the quartic, sextic and octic potentials with high precision, comparing the results with other techniques available in the literature.

  10. A Comparative Study of Sparse Associative Memories

    Science.gov (United States)

    Gripon, Vincent; Heusel, Judith; Löwe, Matthias; Vermet, Franck

    2016-07-01

    We study various models of associative memories with sparse information, i.e. a pattern to be stored is a random string of 0s and 1s with about log N 1s, only. We compare different synaptic weights, architectures and retrieval mechanisms to shed light on the influence of the various parameters on the storage capacity.

  11. A Comparative Study of Probabilistic Roadmap Planners

    NARCIS (Netherlands)

    Geraerts, R.J.; Overmars, M.H.

    2004-01-01

    The probabilistic roadmap approach is one of the leading motion planning techniques. Over the past eight years the technique has been studied by many different researchers. This has led to a large number of variants of the approach, each with its own merits. It is difficult to compare the different

  12. A comparative study of map use

    DEFF Research Database (Denmark)

    Bouvin, Niels Olof; Brodersen, Ann Christina; Bødker, Susanne

    2006-01-01

    We present a study comparing the handling of three kinds of maps, each on a physical device: a paper map, a tablet-PC based map, and a cellular phone based one. Six groups of users were asked to locate eight landmarks, looking out a window, and using a particular map. We have begun analyzing video...

  13. Sublimation Kinetic Studies of the Zr(tmhd4 Complex

    Directory of Open Access Journals (Sweden)

    T. S. Arul Jeevan

    2013-01-01

    Full Text Available The thermal behaviour of tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionatozirconium(IV, [Zr(tmhd4] was investigated by nonisothermal and isothermal thermogravimetric methods in a high pure nitrogen atmosphere. The influence of the heating rate in dynamic measurements (6, 8, 10, and 12°C/min on activation energy was also studied. The nonisothermal sublimation activation energy values determined following the procedures of Arrhenius, Coats and Redfern, Kissinger, and Flynn-Wall yielded 76±5, 92±2, 81±8, and 72±7 kJ/mol, respectively, and the isothermal sublimation activation energy was found to be 87±4 kJ/mol over the temperature range of 411–462 K. Different reaction mechanisms were used to compare with this value. Analysis of the experimental results suggested that the actual reaction mechanism was an Rn deceleration type.

  14. Distinction between esterases and lipases: a kinetic study with vinyl esters and TAG.

    Science.gov (United States)

    Chahinian, Henri; Nini, Lylia; Boitard, Elisabeth; Dubès, Jean-Paul; Comeau, Louis-Claude; Sarda, Louis

    2002-07-01

    The better to characterize enzymes hydrolyzing carboxyl ester bonds (carboxyl ester hydrolases), we have compared the kinetic behavior of various lipases and esterases against solutions and emulsions of vinyl esters and TAG. Short-chain vinyl esters are hydrolyzed at comparable rates by esterases and lipases and have higher limits of solubility in water than corresponding TAG. Therefore, they are suited to study the influence of the physical state of the substrate on carboxyl ester hydrolase activity within a large concentration range. Enzymes used in this study are TAG lipases from microorganisms, lipases from human and guinea pig pancreas, pig liver esterase, and acetylcholinesterase. This study also includes cutinase, a fungal enzyme that displays functional properties between esterases and lipases. Esterases display maximal activity against solutions of short-chain vinyl esters (vinyl acetate, vinyl propionate, and vinyl butyrate) and TAG (triacetin, tripropionin, and tributyrin). Half-maximal activity is reached at ester concentrations far below the solubility limit. The transition from solution to emulsion at substrate concentrations exceeding the solubility limit has no effect on esterase activity. Lipases are active on solutions of short-chain vinyl esters and TAG but, in contrast to esterases, they all display maximal activity against emulsified substrates and half-maximal activity is reached at substrate concentrations near the solubility limit of the esters. The kinetics of hydrolysis of soluble substrates by lipases are either hyperbolic or deviate from the Michaelis-Menten model and show no or weak interfacial activation. The presence of molecular aggregates in solutions of short-chain substrates, as evidenced by a spectral dye method, likely accounts for the activity of lipases against soluble esters. Unlike esterases, lipases hydrolyze emulsions of water-insoluble medium- and long-chain vinyl esters and TAG such as vinyl laurate, trioctanoin, and

  15. Kinetic study of pentosan solubility during heating and reacting processes of steam treatment of green bamboo.

    Science.gov (United States)

    Luo, Xiaolin; Ma, Xiaojuan; Hu, Huichao; Li, Canghai; Cao, Shilin; Huang, Liulian; Chen, Lihui

    2013-02-01

    Green bamboo was hydrolyzed over a range of durations at different temperatures. A simple pseudo-homogeneous irreversible first order kinetic model was developed to describe pentosan solubility during steam treatment of green bamboo. To avoid the influence of soluble pentosan during heating process, kinetic parameters were effectively dissolved based on the data in the reacting process. Moreover, the pentosan solubility during heating process was also well modeled by numerical algorithm method. According to the origin of H factor, a modified parameter called steam treatment factor (f(P)) was proposed in this paper based on the determined kinetic constants. Finally, residual pentosan in whole process could be predicted properly based on the f(P) and the introducing of potential hydrolysis degree (h(d)). After using f(P) to combine reaction temperature and time into a single factor, comparative result showed that steam treatment is more effective for removing pentosan compared with hot water extraction.

  16. Study on biodegradation of Mazut by newly isolated strain Enterobacter cloacae BBRC10061: improving and kinetic investigation

    Directory of Open Access Journals (Sweden)

    Khorasani Alireza Chackoshian

    2013-01-01

    Full Text Available Abstract Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration was assayed based on gradual addition method. Also different kinetic models were used to evaluate kinetics of the process. Results showed that gradual addition method has been a beneficial technique for improvement of mazut degradation because bacterial induction to produce biosurfactant and essential enzymes for cracking mazut was higher during process. Although addition of more mazut increased the rate of biodegradation but percentage of degradation decreased. pH of medium decreased during biodegradation period while electric potential increased. Also the biodegradation kinetics was not fitted with the biokinetic models; therefore kinetics of biodegradation of mazut has to be studied by new models.

  17. Study on Biodegradation of Mazut by Newly Isolated strain Enterobacter Cloacae BBRC10061: Improving and Kinetic Investigation

    Directory of Open Access Journals (Sweden)

    Alireza Chackoshian Khorasan

    2013-01-01

    Full Text Available Mazut as a source content of various hydrocarbons is hard to be degraded and its cracking could turn mazut into useful materials. Nevertheless degradation of mazut by routine methods is too expensive but application of indigenous microorganisms as biocatalysts could be effective and important to lower the costs and expand its consumption. Mazut biodegradation can be improved using various strategies; Therefore in this study newly isolated strain Enterobacter cloacae BBRC 10061 was used in a method of gradual addition of mazut into medium and its results were compared with simple addition method. To investigate degradation of mazut by BBRC 10061, influence of increase of mazut concentration was assayed based on gradual addition method. Also different kinetic models were used to evaluate kinetics of the process. Results showed that gradual addition method has been a beneficial technique for improvement of mazut degradation because bacterial induction to produce biosurfactant and essential enzymes for cracking mazut was higher during process. Although addition of more mazut increased the rate of biodegradation but percentage of degradation decreased. pH of medium decreased during biodegradation period while electric potential increased. Also the biodegradation kinetics was not fitted with the biokinetic models; therefore kinetics of biodegradation of mazut has to be studied by new models.

  18. Thermogravimetric analysis and kinetic study of formation of lithium titanate by solid state route

    Energy Technology Data Exchange (ETDEWEB)

    Sonak, Sagar; Jain, Uttam [Fusion Reactor Materials Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Sahu, Ashok Kumar [Glass and advanced Materials Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kumar, Sanjay; Krishnamurthy, Nagaiyar [Fusion Reactor Materials Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2015-02-15

    The kinetics of formation of lithium titanate from the solid state reaction of lithium carbonate and titanium oxide was studied using non-isothermal thermogravimetric technique. Thermogravimetric data for the reaction of lithium carbonate and titanium oxide was obtained at various heating rates. The methods such as Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose were used to estimate the kinetic parameters from the obtained thermogravimetric data. The average activation energy for the formation of lithium titanate by solid state route was found to be 243 kJ/mol K. The reaction mechanism was determined by the method given by Malek. It was found that the three dimensional diffusion model best describes the reaction kinetics. A kinetic equation describing the reaction is proposed and reaction mechanism is discussed.

  19. Water disinfection with UVC radiation and H2O2. A comparative study.

    Science.gov (United States)

    Labas, Marisol Daniela; Brandi, Rodolfo Juan; Zalazar, Cristina Susana; Cassano, Alberto Enrique

    2009-05-01

    A generalized kinetic model resulting from several modifications of the one originally known as the Series Event Model has been applied to describe three different disinfection processes and compare their efficiencies. The work was performed in a well-defined, versatile batch reactor employing Escherichia coli as a subrogate bacteria. The following systems were studied: (i) UVC radiation alone, (ii) hydrogen peroxide alone and (iii) UVC radiation combined with hydrogen peroxide. The kinetic parameters of the three models were determined. Within the range of studied operating conditions, the use of UVC alone has shown to produce the best results.

  20. Adsorption of Congo Red by Ni/Al-CO3: Equilibrium, Thermodynamic and Kinetic Studies

    Directory of Open Access Journals (Sweden)

    N. Ayawei

    2015-09-01

    Full Text Available Experimental investigations were carried out using Ni/Al-CO3 layered double hydroxide as adsorbent for removal of toxic anionic dye namely Congo red from aqueous solutions. The effect of contact time, initial dye concentration and temperature were experimentally studied in batch mode to evaluate the kinetic, equilibrium and thermodynamic parameters of the adsorption process. Experimental results revealed that the degradation of the dye is mostly dependent on temperature. The dye degradation process obeyed the zero-order kinetic model, first-order kinetic model, second-order kinetic model, pseudo second order kinetic and third order kinetic model with correlation coefficient values 1, 0.9998, 0.9999, 0.9999 and 0.9997 respectively. Langmuir, Freundlich, Temkin and Dubinin-Kaganer-Radushkevic isotherms were applied to the equilibrium data and was well described by all. Thermodynamic studies showed congo red adsorption on the layered double hydroxide was endothermic and spontaneous in nature. The results indicate that layered double hydroxide could be employed as alternative for removal of anionic dyes from industrial wastewater.

  1. Kinetic studies of the polygalacturonase enzyme from Colletotrichum lindemuthianum.

    Science.gov (United States)

    Waksman, G; Turner, G; Walmsley, A R

    1992-07-15

    The intrinsic protein fluorescence of the polygalacturonase from Colletotrichium lindemuthianum was exploited in stopped-flow experiments aimed at elucidating the kinetic mechanism for this enzyme. Binding of the polymeric substrate polygalacturonic acid (PGA) essentially produced a triphasic fluorescence profile. There was an initial rapid quench in fluorescence, consistent with the rapid formation of the enzyme-substrate complex, with an equilibrium constant of about 8 x 10(-4)% (w/v) PGA (about 0.27 microM). There then followed a near-constant fluorescence phase, attributable to turnover of the enzyme-substrate complex as a steady-state intermediate. As the concentration of the steady-state intermediate became depleted, towards the end of the reaction, there was a partial return of the fluorescence intensity. This phase is attributed to a final, single turnover of the enzyme at the end of the reaction. The fluorescence intensity does not return to its original level due to product remaining bound at the end of the reaction.

  2. Comparative kinetic study and microwaves non-thermal effects on the formation of poly(amic acid) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4'-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction activated by microwave, ultrasound and conventional heating.

    Science.gov (United States)

    Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

    2011-01-01

    Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

  3. Comparative Kinetic Study and Microwaves Non-Thermal Effects on the Formation of Poly(amic acid 4,4′-(Hexafluoroisopropylidenediphthalic Anhydride (6FDA and 4,4′-(Hexafluoroisopropylidenebis(p-phenyleneoxydianiline (BAPHF. Reaction Activated by Microwave, Ultrasound and Conventional Heating

    Directory of Open Access Journals (Sweden)

    Hugo Mendoza Tellez

    2011-10-01

    Full Text Available Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid synthesized from (6FDA dianhydride and (BAPHF diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH, microwave (MW and ultrasound irradiation (US. Results show that the polycondensation rate decreases (MW > US > CH and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

  4. A Comparative Study on Author's Unreliability

    Institute of Scientific and Technical Information of China (English)

    林映凡

    2016-01-01

    Literature appreciation usually follows a"writer-text-reader" process. The author is an inseparable part in literary discussion. Most literary schools have debate on the author's status, which is mainly sorted into two kinds: reliable author or unreliable author. This paper makes a comparative study on the author's status, which is mainly from the perspectives of New Criticism and Deconstruction. Both of them go for unreliability of the author. They share similarities but also bear differences.

  5. Comparative Study on Richard Ⅲ and Macbeth

    Institute of Scientific and Technical Information of China (English)

    冯丽霞; 闫继苗; 徐婷婷

    2013-01-01

    Shakespeare is one of the most prominent drama writers all over the world. His masterpiece displays vivid, delicate and profound humanity. Richard Ⅲ and Macbeth as the main heroes in his two tragedies of the same theme, share quite a lot of simi⁃larities and differences, yet resulting in sharply different readers’response to their fates. The comparative study on these two char⁃acters is aimed at helping readers better understand the two tragedies.

  6. Friendship in Latin American Social Comparative Studies

    Directory of Open Access Journals (Sweden)

    Agnaldo Garcia

    2016-06-01

    Full Text Available Friendship has been traditionally investigated in the field of interpersonal relationships using different theoretical frameworks and approaches. This paper discusses the possibility of investigating friendship from a comparative Latin American perspective, based on a wide literature review on the subject. Based on the theoretical proposals of Hinde (1997 for the investigation of interpersonal relationships, the paper considers that friendship involves several levels of complexity and affects and is affected by distinct dimensions of Latin American society. The paper recognizes that comparative studies have placed the importance of friends and friendship in areas such as economy, health, education, and migration, among others. As expected, Latin American comparative studies are more frequent in some disciplines, mainly those based on censuses data, and theoretically related to social-economic and demographic concepts, including social networks and social capital. The possibility of developing a Latin American perspective for the study of friendship requires not only the need of empirical but also theoretical advances, as well as scientific cooperation and innovation. Friendship is seen as relevant for the constitution of the social tissue of Latin American society, being affected and affecting different areas and levels. In the social economic dimension, friends are relevant, specifically in Latin America, to themes such as poverty and social vulnerability. Some future possibilities for investigation are discussed.

  7. Experimental and Chemical Kinetic Modeling Study of Dimethylcyclohexane Oxidation and Pyrolysis

    KAUST Repository

    Eldeeb, Mazen A.

    2016-08-30

    A combined experimental and chemical kinetic modeling study of the high-temperature ignition and pyrolysis of 1,3-dimethylcyclohexane (13DMCH) is presented. Ignition delay times are measured behind reflected shock waves over a temperature range of 1049–1544 K and pressures of 3.0–12 atm. Pyrolysis is investigated at average pressures of 4.0 atm at temperatures of 1238, 1302, and 1406 K. By means of mid-infrared direct laser absorption at 3.39 μm, fuel concentration time histories are measured under ignition and pyrolytic conditions. A detailed chemical kinetic model for 13DMCH combustion is developed. Ignition measurements show that the ignition delay times of 13DMCH are longer than those of its isomer, ethylcyclohexane. The proposed chemical kinetic model predicts reasonably well the effects of equivalence ratio and pressure, with overall good agreement between predicted and measured ignition delay times, except at low dilution levels and high pressures. Simulated fuel concentration profiles agree reasonably well with the measured profiles, and both highlight the influence of pyrolysis on the overall ignition kinetics at high temperatures. Sensitivity and reaction pathway analyses provide further insight into the kinetic processes controlling ignition and pyrolysis. The work contributes toward improved understanding and modeling of the oxidation and pyrolysis kinetics of cycloalkanes.

  8. A kinetic study of non-isothermal decomposition process of anhydrous nickel nitrate under air atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jankovic, B., E-mail: bojanjan@ffh.bg.ac.r [Faculty of Physical Chemistry, University of Belgrade, Studentski Trg 12-16, P. O. Box 137, 11001 Belgrade (Serbia); Mentus, S. [Faculty of Physical Chemistry, University of Belgrade, Studentski Trg 12-16, P. O. Box 137, 11001 Belgrade (Serbia); Jelic, D. [Faculty of Medicine, University of Banja Luka, 78000 Banja Luka (Bosnia and Herzegowina)

    2009-08-01

    The non-isothermal decomposition process of anhydrous nickel nitrate under air atmosphere was investigated. The kinetic analysis of decomposition process was performed using Friedman (FR), Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) isoconversional methods. The kinetic model was determined by the Malek's method. The composite differential method I was used for checking the established reaction model. It was found that the value of E{sub a} calculated by composite differential method (E{sub a}=147.1 kJ mol{sup -1}) represents the medium value between the values of the apparent activation energy calculated by FR (E{sub a,FR}=152.8 kJ mol{sup -1}) and FWO (E{sub a,FWO}=143.1 kJ mol{sup -1}) methods. Using two special functions (y(alpha) and z(alpha)), it was found that the two-parameter autocatalytic model (Sestak-Berggren (SB) kinetic model) with kinetic exponents M=0.23 and N=1.14 is the most adequate one to describe the decomposition kinetics of the studied system at various heating rates. The obtained non-isothermal differential conversion curves from the experimental data show the results being accordant with those theoretically calculated. It was concluded that the SB kinetic model can be used for a quantitative description of non-isothermal decomposition process of anhydrous nickel nitrate which involves the partially overlapping nucleation and growth phases.

  9. Kinetic study of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst

    Institute of Scientific and Technical Information of China (English)

    Farnaz; Tahriri; Zangeneh; Abbas; Taeb; Khodayar; Gholivand; Saeed; Sahebdelfar

    2013-01-01

    The kinetics of propane dehydrogenation and catalyst deactivation over Pt-Sn/Al2O3 catalyst were studied.Performance test runs were carried out in a fixed-bed integral reactor.Using a power-law rate expression for the surface reaction kinetics and independent law for deactivation kinetics,the experimental data were analyzed both by integral and a novel differential method of analysis and the results were compared.To avoid fluctuation of time-derivatives of conversion required for differential analysis,the conversion-time data were first fitted with appropriate functions.While the time-zero and rate constant of reaction were largely insensitive to the function employed,the rate constant of deactivation was much more sensitive to the function form.The advantage of the proposed differential method,however,is that the integration of the rate expression is not necessary which otherwise could be complicated or impossible.It was also found that the reaction is not limited by external and internal mass transfer limitations,implying that the employed kinetics could be considered as intrinsic ones.

  10. Multifactorial study and kinetics of signal development in ferrous-methylthymol blue-gelatin gel dosimeters.

    Science.gov (United States)

    Penev, Kalin I; Mequanint, Kibret

    2017-05-01

    To develop and characterize a ferrous-methylthymol blue-gelatin gel dosimeter with low optical background and appropriate additives for reduced rate of auto-oxidation and diffusion. A mixed-level multifactorial design of experiments was used to test the effects of the concentrations of sulfuric acid, 5-nitro-1,10-phenanthroline (Nn), and glyoxal (Gx) on the background absorbance, dose sensitivity, and auto-oxidation of the tested gel dosimeter. The dosimetric properties of the proposed ferrous-methylthymol blue-gelatin dosimeter, doped with Nn and Gx, were compared with the undoped formulation and with ferrous-xylenol orange-gelatin gel dosimeters. Irradiations were performed in both small-scale cuvette samples and large 400-mL bulk samples. In addition to that, a new kinetic model for the signal development postirradiation was derived based on chemical principles and used for comparison of the different formulations. The new formulation showed a reduced auto-oxidation rate, while maintaining low background absorbance relative to the common ferrous-xylenol orange-gelatin gel dosimeter. Compared with undoped ferrous-xylenol orange or ferrous-methylthymol blue gels, the dose sensitivity of the new formulation is approximately 2 to 3 times lower, but remains clinically adequate. A previously unreported dose rate dependence of the dose sensitivity was observed, and a new kinetic model for the signal development postirradiation was used to investigate this effect. Similar dose rate dependences in gels containing either methylthymol blue or xylenol orange, with or without doping with Nn and Gx, were observed, suggesting that the low ferrous ammonium sulfate concentrations used in studied formulations were responsible for this effect. A multifactorial design of experiments and a new kinetic model for the signal development postirradiation were successfully employed to optimize the composition and characterize the properties of a new ferrous-methylthymol blue-gelatin gel

  11. Multiple dose bioequivalence study with josamycin propionate, a drug with highly variable kinetics, in healthy volunteers.

    Science.gov (United States)

    Van Hoogdalem, E J; Terpstra, I J; Krauwinkel, W J; Volkers-Kamermans, N J; Baven, A L; Verschoor, J S

    1996-05-01

    Josamycin is a macrolide antibiotic with considerable intra- and interindividual variability in kinetics. In the present study bioequivalence of an intact and dispersed josamycin Solutab tablet, containing 1,000 mg of josamycin in the form of josamycin propionate ester, was tested versus a Josacine 1,000 mg reference sachet. The design of this bioequivalence study was adapted to the drug's pharmacokinetic variability, comprising testing in steady-state, testing the reference in replicate, and maintaining a widened bioequivalence margin. The study was performed in a group of 24 male and 12 female healthy subjects, according to a 3-treatment 4-period crossover design. Blood sampling for establishing josamycin propionate and josamycin base serum level profiles were collected during the 12 h dosing interval on day 4. Steady-state serum levels were reached on day 4. With the reference sachet mean peak levels of 1.02 micrograms/ml and 0.36 microgram/ml were observed for parent drug and metabolite, respectively, reached at peak times of 1.5 h and 1.8 h. Comparable profiles were observed with the intact and dispersed Solutab tablets, both tending towards higher serum levels than the sachet. In terms of josamycin propionate levels as well as josamycin base levels, the intact and dispersed Solutab tablet was bioequivalent with the referent sachet within the preset 0.70-1.43 margins. Variability in josamycin kinetics proved to be substantial, maximum differences in peak levels and AUC values being about 10-fold between individuals, and 3-fold within individuals. Retrospectively, the multiple dosing regimen appeared not to result in a clear reduction of intrasubject variability.

  12. Studies on thermal degradation kinetics of thermal and UV cured N-(4-hydroxy phenyl) maleimide derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Pitchaimari, G.; Vijayakumar, C.T., E-mail: ctvijay22@yahoo.com

    2014-01-10

    Graphical abstract: - Highlights: • UV cure materials are more thermally stable than the thermally cured materials. • Cyanate ester functionalization offers better thermal stability. • The Ea values for Poly NVPs are low compared to other materials investigated. • The UV cured materials showed higher Ea values than the thermally cured materials. - Abstract: The results of the studies concerning the thermal and photo initiated copolymerization of N-(4-acryloyloxy phenyl) maleimide (AX), N-(4-methacryloyloxy phenyl) maleimide (MAX) and N-(4-cyanato phenyl) maleimide (CNX) with N-vinyl-2-pyrrolidone (NVP) were presented. The structures of all the copolymers prepared were confirmed by FTIR studies. The thermogravimetric studies of both the thermal and UV cured materials indicated that the UV cured materials were comparatively thermally more stable than the thermally polymerized materials during thermal degradation. Of all the materials investigated, liquid composition having NVP and CNX cured by UV irradiation showed better thermal stability. The degradation kinetic studies using Flynn–Wall–Ozawa, Vyazovkin and Friedman methods showed that the activation energies (Ea) for the thermal degradation of polymeric materials cured by UV irradiation were slightly higher than the Ea values calculated for the thermally polymerized materials.

  13. Reactivity of γ-Terpinene with NO3 radicals: experimental approach for kinetic and mechanistic study.

    Science.gov (United States)

    Fouqueau, Axel; Cirtog, Manuela; Le Quilleuc, Meryll; Cazaunau, Mathieu; Pangui, Edouard; Duncianu, Marius; Doussin, Jean-François; Picquet-Varrault, Bénédicte

    2017-04-01

    Biogenic Volatile Organic Compounds (BVOC) are highly emitted by vegetation and play a key role in atmospheric chemistry. They are very reactive with atmospheric oxidants (OH, NO3, ozone) and significantly contribute to the formation of Secondary Organic Aerosol (SOA) at the global scale [1]. In addition, night-time chemistry initiated by NO3 radicals leads to the formation of organic nitrates which behave as reservoirs for reactive nitrogen. However, the reactivity of NO3 radical with BVOCs other than isoprene and α- and β-pinene, remains poorly understood. Among the BVOCs, γ-Terpinene is one of the most emitted by vegetation[2]. Two kinetic works were previously published on γ-Terpinene [3] [4], but mechanistic has never been studied. Thus, the aim of this work is to study the reactivity of γ-Terpinene with NO3 by performing experiments in simulation chambers. Kinetic, mechanism and SOA yield will be investigated. For this purpose, two different simulation chambers have been used: - First one, consisting of a Pyrex reactor of 1 m3 [5] coupled to a long path in situ FTIR spectrometer and a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) in NO+ mode which was internally developed in LISA, to measure organic nitrates concentration. - Second one, the CESAM chamber (http://cesam.cnrs.fr) [6] is a 4.2 m3 stainless steel chamber which permits to conduct SOA experiments at different temperature and relative humidity. In situ FTIR and PTR-ToF-MS are used to measure gaseous concentrations, and a SMPS was used to characterize particulate phase. Kinetic and mechanistic results will be discussed and compared with the literature values. References [1] Brown S. S., Stutz J., Nighttime radical observations and chemistry. Chem. Soc. Rev. (2012) 41, 6405-6447 [2] Helmig D., Klinger L.F., et al., Biogenic volatile organic compound emissions (BVOCs) I. Identifications from three continental sites in the U.S. Chemosphere. (1999), Vol. 38, No. 9, pp. 2163

  14. Experimental study and kinetic analysis of the oxidation of light hydrocarbons mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Rota, R.; Bonini, F.; Morbidelli, M.; Carra, S. [Politecnico di Milano (Italy). Dipt. di Chimica Fisica Applicata

    1996-07-01

    The combustion of various C{sup 1}-C{sub 2} hydrocarbon mixtures has been experimentally investigated in a continuous perfectly stirred reactor, in a temperature range from 1,000 to 1,300 K, and at stoichiometric ratio values between 0.5 and 1.5. The concentration values of several molecular species have been measured by GC analysis. The data obtained have been compared with the predictions of two different detailed kinetic models; both fail to predict the experimental trends in various situations. This leads to the conclusion that experimental data based on mixtures of hydrocarbons must be obtained to validate detailed kinetic mechanisms.

  15. Theoretical study of atoms by the electronic kinetic energy density and stress tensor density

    CERN Document Server

    Nozaki, Hiroo; Tachibana, Akitomo

    2016-01-01

    We analyze the electronic structure of atoms in the first, second and third periods using the electronic kinetic energy density and stress tensor density, which are local quantities motivated by quantum field theoretic consideration, specifically the rigged quantum electrodynamics. We compute the zero surfaces of the electronic kinetic energy density, which we call the electronic interfaces, of the atoms. We find that their sizes exhibit clear periodicity and are comparable to the conventional atomic and ionic radii. We also compute the electronic stress tensor density and its divergence, tension density, of the atoms, and discuss how their electronic structures are characterized by them.

  16. Mechanism and Kinetics Study for Photocatalytic Oxidation Degradation: A Case Study for Phenoxyacetic Acid Organic Pollutant

    Directory of Open Access Journals (Sweden)

    Kian Mun Lee

    2015-01-01

    Full Text Available Photocatalysis is a rapidly expanding technology for wastewater treatment, including a wide range of organic pollutants. Thus, understanding the kinetics and mechanism of the photocatalytic oxidation (PCO for degradation of phenoxyacetic acid (PAA is an indispensable component of risk assessment. In this study, we demonstrated that the central composite design (CCD coupled with response surface methodology (RSM was successfully employed to probe the kinetics and mechanism of PCO degradation for PAA using an efficient zinc oxide (ZnO photocatalyst. In our current case study, four independent factors such as ZnO dosage, initial concentration of PAA, solution pH, and reaction time on the PCO degradation for PAA were examined in detail. Based on our results obtained from RSM analyses, an efficient pathway leading to the high degradation rate (>90% was applying 0.4 g/L of ZnO dosage with 16 mg/L of concentration of PAA at pH 6.73 for 40 minutes. The experimental results were fitted well with the derived response model with R2 = 0.9922. This study offers a cost-effective way for probing our global environmental water pollution issue.

  17. Chlorine dioxide oxidation of Escherichia coli in water - A study of the disinfection kinetics and mechanism.

    Science.gov (United States)

    Ofori, Isaac; Maddila, Suresh; Lin, Johnson; Jonnalagadda, Sreekantha B

    2017-06-07

    This study investigated the kinetics and mechanism of chlorine dioxide (ClO2) inactivation of a Gram-negative bacteria Escherichia coli (ATCC 35218) in oxidant demand free (ODF) water in detail as a function of disinfectant concentration (0.5-5.0 mg/L), water pH (6.5-8.5), temperature variations (4-37°C) and bacterial density (10(5)-10(7) cfu/mL). The effects of ClO2 on bacterial cell morphology, outer membrane permeability, cytoplasmic membrane disruption and intracellular enzymatic activity were also studied to elucidate the mechanism of action on the cells. Increasing temperature and disinfectant concentration were proportional to the rate of cell killing, but efficacy was found to be significantly subdued at 0.5 mg/L and less dependent on the bacterial density. The bactericidal efficiency was higher at alkaline pH of 8 or above as compared to neutral and slightly acidic pH of 7 and 6.5 respectively. The disinfection kinetic curves followed a biphasic pattern of rapid inactivation within the initial 2 min which were followed by a tailing even in the presence of residual biocide. The curves were adequately described by the Cavg Hom model. Transmission Electron Microscopy images of the bacteria cells exposed to lethal concentrations of ClO2 indicated very little observable morphological damage to the outer membranes of the cells. ClO2 however was found to increase the permeability of the outer and cytoplasmic membranes leading to the leakage of membrane components such as 260 nm absorbing materials and inhibiting the activity of the intracellular enzyme β-D-galactosidase. It is suggested that the disruption of the cytoplasmic membrane and subsequent efflux of intracellular components result in the inactivation of the Gram-negative bacteria.

  18. A study of the kinetic, dielectric, and rheological properties of thermosetting resins used in pultruded polymer composites

    Science.gov (United States)

    Shanku, Reshma

    A comprehensive analysis has been conducted of the curing behavior of AOC VIBRINRTM E-606-6 (medium reactivity isophthalic), E-964 (high reactivity isophthalic), and P-341 (highest reactivity) polyester resins, and Shell EPON 9310 resin/EPON 9360 curing agent/EPON 537 accelerator resin system using calorimetric, dielectric, and rheological methods. The unsaturated polyester resins were cured with two different catalysts at three levels of concentration. Calorimetry and dielectrometry were employed to obtain polyester resin curing properties for the resin formulations studied. Rheological characterization of selected polyester resin formulations and the EPON 9310 resin system were also conducted. Kinetic parameters for all resin formulations were determined using a differential scanning calorimeter (DSC) by dynamic and isothermal methods. The dynamic and isothermal kinetic parameters obtained were used to generate heat flow values which were compared to the experimental DSC heat flow recorded; kinetic parameters that accurately modeled the pultrusion process were selected. The kinetic parameters were used in a numerical model to predict temperatures and degrees of cure under pultrusion processing conditions. The results obtained from the in-situ dielectric tests conducted on the pultruder in the Composites Material Laboratory at the University of Mississippi were compared to the degree of cure predictions from the numerical model and the experimental degree of cure from calorimetric analysis. Prior to the in-situ pultrusion studies, small quantities of resin formulations were tested for their dielectric cure properties when heated in an oven simulating pultrusion processing temperatures and rate of heating. This technique allowed small quantities of resins to be tested for degrees of cure. It was determined that such screening tests can be effectively conducted and can aid in pultrusion process planning. Complex viscosity profiles until gelation were generated for

  19. Comparative study of INPIStron and spark gap

    Science.gov (United States)

    Han, Kwang S.; Lee, Ja H.

    1993-01-01

    An inverse pinch plasma switch, INPIStron, was studied in comparison to a conventional spark gap. The INPIStron is under development for high power switching applications. The INPIStron has an inverse pinch dynamics, opposed to Z-pinch dynamics in the spark gap. The electrical, plasma dynamics and radiative properties of the closing plasmas have been studied. Recently the high-voltage pulse transfer capabilities or both the INPIStron and the spark gap were also compared. The INPIStron with a low impedance Z = 9 ohms transfers 87 percent of an input pulse with a halfwidth of 2 mu s. For the same input pulse the spark gap of Z = 100 ohms transfers 68 percent. Fast framing and streak photography, taken with an TRW image converter camera, was used to observe the discharge uniformity and closing plasma speed in both switches. In order to assess the effects of closing plasmas on erosion of electrode material, emission spectra of two switches were studied with a spectrometer-optical multi channel analyzer (OMA) system. The typical emission spectra of the closing plasmas in the INPIStron and the spark gap showed that there were comparatively weak carbon line emission in 658.7 nm and copper (electrode material) line emissions in the INPIStron, indicating low erosion of materials in the INPIStron.

  20. EFQPSK Versus CERN: A Comparative Study

    Science.gov (United States)

    Borah, Deva K.; Horan, Stephen

    2001-01-01

    This report presents a comparative study on Enhanced Feher's Quadrature Phase Shift Keying (EFQPSK) and Constrained Envelope Root Nyquist (CERN) techniques. These two techniques have been developed in recent times to provide high spectral and power efficiencies under nonlinear amplifier environment. The purpose of this study is to gain insights into these techniques and to help system planners and designers with an appropriate set of guidelines for using these techniques. The comparative study presented in this report relies on effective simulation models and procedures. Therefore, a significant part of this report is devoted to understanding the mathematical and simulation models of the techniques and their set-up procedures. In particular, mathematical models of EFQPSK and CERN, effects of the sampling rate in discrete time signal representation, and modeling of nonlinear amplifiers and predistorters have been considered in detail. The results of this study show that both EFQPSK and CERN signals provide spectrally efficient communications compared to filtered conventional linear modulation techniques when a nonlinear power amplifier is used. However, there are important differences. The spectral efficiency of CERN signals, with a small amount of input backoff, is significantly better than that of EFQPSK signals if the nonlinear amplifier is an ideal clipper. However, to achieve such spectral efficiencies with a practical nonlinear amplifier, CERN processing requires a predistorter which effectively translates the amplifier's characteristics close to those of an ideal clipper. Thus, the spectral performance of CERN signals strongly depends on the predistorter. EFQPSK signals, on the other hand, do not need such predistorters since their spectra are almost unaffected by the nonlinear amplifier, Ibis report discusses several receiver structures for EFQPSK signals. It is observed that optimal receiver structures can be realized for both coded and uncoded EFQPSK

  1. Comparative study of hydrogenated and lithiated superhalogens

    Science.gov (United States)

    Xu, Li-Na; Li, Ying; Liu, Jia-Yuan; Wu, Di; Sun, Yan-Bo; Li, Zhi-Ru

    2016-09-01

    The structural features, properties and stability of two kinds of representative superhalogen compounds, namely hydrogenated superhalogens and lithiated superhalogens, are theoretically studied in detail, providing further insight into the behavior of superhalogens. According to topological analysis of the electron localization function, most of superhalogen clusters as a whole combine with Li atom through ionic bond(s). In contrast, the H atom tends to bind with superhalogen by covalent bond although a portion of superhalogens are broken upon hydrogenation. In addition, the electric properties of these superhalogen compounds are also obtained and compared with those of traditional acid and salt molecules.

  2. Comparative testing of disinfectant efficacy on planktonic bacteria and bacterial biofilms using a new assay based on kinetic analysis of metabolic activity.

    Science.gov (United States)

    Günther, F; Scherrer, M; Kaiser, S J; DeRosa, A; Mutters, N T

    2017-03-01

    The aim of our study was to develop a new reproducible method for disinfectant efficacy testing on bacterial biofilms and to evaluate the efficacy of different disinfectants against biofilms. Clinical multidrug-resistant strains were chosen as test isolates to ensure practical relevance. We compared the standard qualitative suspension assay for disinfectant testing, which does not take into account biofilm formation, to the new biofilm viability assay that uses kinetic analysis of metabolic activity in biofilms after disinfectant exposure to evaluate disinfectant efficacy. In addition, the efficacy of four standard disinfectants to clinical isolates was tested using both methods. All tested disinfectants were effective against test isolates when in planktonic state using the standard qualitative suspension assay, while disinfectants were only weakly effective against bacteria in biofilms. Disinfectant efficacy testing on planktonic organisms ignores biofilms and overestimates disinfectant susceptibility of bacteria. However, biofilm forming, e.g. on medical devices or hospital surfaces, is the natural state of bacterial living and needs to be considered in disinfectant testing. Although bacterial biofilms are the predominant manner of bacterial colonization, most standard procedures for antimicrobial susceptibility testing and efficacy testing of disinfectants are adapted for application to planktonic bacteria. To our knowledge, this is the first study to use a newly developed microplate-based biofilm test system that uses kinetic analysis of the metabolic activity in biofilms, after disinfectant exposure, to evaluate disinfectant efficacy. Our study shows that findings obtained from disinfectant efficacy testing on planktonic bacteria cannot be extrapolated to predict disinfectant efficacy on bacterial biofilms of clinically relevant multidrug-resistant organisms. © 2016 The Society for Applied Microbiology.

  3. Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii

    Institute of Scientific and Technical Information of China (English)

    CHEN Xin; CHEN Hua; CAI Bingna; LIU Qingqin; SUN Huili

    2013-01-01

    A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity,even at low temperature,but the characteristics of the hydrolysis with this enzyme are still unclear.The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties ofprotease 894.After investigating the intrinsic relationship between the degree of hydrolysis and several factors,including initial reaction pH,temperature,substrate concentration,enzyme concentration,and hydrolysis time,the kinetics model was established.This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0,temperature of 30℃,substrate concentration of 10% (w/v),enzyme concentration of 2 500 U/g,and hydrolysis time of 160 min.The kinetic characteristics of the protease for the hydrolysis of P.martensii were obtained.The inactivation constant was found to be 15.16/min,and the average relative error between the derived kinetics model and the actual measurement was only 3.04%,which indicated a high degree of fitness.Therefore,this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease,which has potential applications in the food industry.

  4. Copper and cobalt complexes of octadentate azamacrocycles: spectrophotometric titration, stopped-flow kinetics and crystallographic study.

    Science.gov (United States)

    Ozay, Hava; Baran, Yakup; Ishii, Youichi

    2011-12-01

    Details of complex formation kinetics are reported for tetrakis(2-hydroxyethyl) substituted cyclen (L(1)) and cyclam (L(2)) with Cu(II) and Co(II). Stopped-flow kinetics and spectroscopic titration methods were employed for the activation parameters and stability constants, respectively. X-ray studies revealed that the pendant 2-hydroxyethyl groups are not equivalent: two are folded over the macrocycle and maintained by intramolecular hydrogen bonds while the others are extended and pointed away from the macrocyclic cavity. Complex formation kinetics and spectroscopic titration were performed in aqueous acidic buffer solutions. Thermodynamic and kinetic parameters revealed that the ring size of the macrocycles plays an extremely important role for each metal ion studied. Stopped-flow kinetic measurements explained the mechanism of the complex formation process of both Cu(II) and Co(II) which proceed in outer-sphere interactions with ligands. There are two steps in the complex formation of the system studied. The initial step is a second order reaction between the metal ion and macrocycle with a second order rate constant.

  5. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Oana DUMITRASCU

    2014-11-01

    Full Text Available The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms, University of Applied Sciences Wiesbaden Rüsselsheim, University of Applied Sciences Frankfurt am Main and Nürtingen-Geislingen University have been analysed and their similarities and differences have been identified. The collected data, based on the established sample, is evaluated through univariate and bivariate analysis. In accordance with the evaluated sample, specific gaps from each region are identified regarding the curricular offer of the analysed universities. As a result to the conducted study, recommendations for the University of Applied Sciences Worms regarding the student’s satisfaction concerning the curricular offer are presented.

  6. CURRICULAR OFFER INFLUENCING STUDENTS’ SATISFACTION: COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Oana DUMITRASCU

    2014-11-01

    Full Text Available The main objective of the study is the determination of students’ satisfaction regarding curricular activities. The study has been accomplished using the qualitative and quantitative research, using the bibliographic study, various secondary sources and different primary sources. The study is developed with a marketing research and accomplished using the survey method. 699 students from four universities have been questioned. Due to a comparative study the University of Applied Sciences Worms, University of Applied Sciences Wiesbaden Rüsselsheim, University of Applied Sciences Frankfurt am Main and Nürtingen-Geislingen University have been analysed and their similarities and differences have been identified. The collected data, based on the established sample, is evaluated through univariate and bivariate analysis. In accordance with the evaluated sample, specific gaps from each region are identified regarding the curricular offer of the analysed universities. As a result to the conducted study, recommendations for the University of Applied Sciences Worms regarding the student’s satisfaction concerning the curricular offer are presented.

  7. Shock wave, fluid instability and implosion studies with a kinetic particle approach

    Science.gov (United States)

    Sagert, Irina; Even, Wesley P.; Strother, Terrance T.

    2016-10-01

    Many problems in laboratory plasma physics are subject to flows that move between the continuum and the kinetic regime. The correct description of these flows is crucial in order to capture their impact on the system's dynamical evolution. Examples are capsule implosions in inertial confinement fusion (ICF). Although their dynamics is predominantly shaped by shock waves and fluid instabilities, non-equilibrium flows in form of deuterium/tritium ions have been shown to play a significant role. We present recent studies with our Monte Carlo kinetic particle code that is designed to capture continuum and kinetic flows in large physical systems with possible applications in ICF studies. Discussed results will include standard shock wave and fluid instability tests and simulations that are adapted towards future ICF studies with comparisons to hydrodynamic simulations. This work used the Wolf TriLAB Capacity Cluster at LANL. I.S. acknowledges support through a Director's fellowship (20150741PRD3) from Los Alamos National Laboratory.

  8. Comparative bioequivalence study of meloxicam drugs

    Directory of Open Access Journals (Sweden)

    Ekut Karieva

    2011-03-01

    Full Text Available The governments of many countries strongly support the production and clinical use of generic medicinal products which are “copies” of patented drugs and can be marked at lower cost. At present time bioequivalence testing is regarded as a useful methodology to perform comparisons among different products containing the same active ingredient. This report presents the results of comparative bioequivalence study of three meloxicam formulations: brand-drug “Melbek” with tablets and capsules of meloxicam developed at the Tashkent Pharmaceutical Institute. The results obtained confirm the bioequivalence of the studied drugs, which indicate about scientifically based approach to the selection of excipients and technological process in the development of the above generic drugs.

  9. A Kinetic Study of the Adiabatic Polymerization of Acrylamide.

    Science.gov (United States)

    Thomson, R. A. M.

    1986-01-01

    Discusses theory, procedures, and results for an experiment which demonstrates the application of basic physics to chemical problems. The experiment involves the adiabatic process, in which polymerization carried out in a vacuum flask is compared to the theoretical prediction of the model with the temperature-time curve obtained in practice. (JN)

  10. Kinetic Studies on State of the Art Solid Oxide Cells

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Introduction The Solid Oxide Fuel Cell (SOFC), which converts hydrogen as well as hydrocarbon fuels directly into electricity, has demonstrated almost comparable performance when operated reversely as Solid Oxide Electrolyser Cell (SOEC) for electrical energy storage as fuels. In both application...

  11. Kinetics study of pyridine biodegradation by a novel bacterial strain, Rhizobium sp. NJUST18.

    Science.gov (United States)

    Shen, Jinyou; Zhang, Xin; Chen, Dan; Liu, Xiaodong; Zhang, Libin; Sun, Xiuyun; Li, Jiansheng; Bi, Huiping; Wang, Lianjun

    2014-06-01

    Biodegradation of pyridine by a novel bacterial strain, Rhizobium sp. NJUST18, was studied in batch experiments over a wide concentration range (from 100 to 1,000 mg l(-1)). Pyridine inhibited both growth of Rhizobium sp. NJUST18 and biodegradation of pyridine. The Haldane model could be fitted to the growth kinetics data well with the kinetic constants μ* = 0.1473 h(-1), K s = 793.97 mg l(-1), K i = 268.60 mg l(-1) and S m = 461.80 mg l(-1). The true μ max, calculated from μ*, was found to be 0.0332 h(-1). Yield coefficient Y X/S depended on S i and reached a maximum of 0.51 g g(-1) at S i of 600 mg l(-1). V max was calculated by fitting the pyridine consumption data with the Gompertz model. V max increased with initial pyridine concentration up to 14.809 mg l(-1) h(-1). The q S values, calculated from [Formula: see text], were fitted with the Haldane equation, yielding q Smax = 0.1212 g g(-1) h(-1) and q* = 0.3874 g g(-1) h(-1) at S m' = 507.83 mg l(-1), K s' = 558.03 mg l(-1), and K i' = 462.15 mg l(-1). Inhibition constants for growth and degradation rate value were in the same range. Compared with other pyridine degraders, μ max and S m obtained for Rhizobium sp. NJUST18 were relatively high. High K i and K i' values and extremely high K s and K s' values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations.

  12. Kinetic and Thermodynamic Studies of the Adsorption of Crystal Violet onto Used Black Tea Leaves

    Directory of Open Access Journals (Sweden)

    Mohammad Abul Hossain

    2013-11-01

    Full Text Available This study presents the kinetic and thermodynamic investigation of the adsorption of crystal violet (CV on used black tea leaves (UBTL from aqueous solution to evaluate the feasibility of the process. The effects of concentration, solution pH and temperature on adsorption kinetics were carried out in batch process. Kinetic studies have shown that the adsorption data partially follow simple first order, second order and pseudo second order kinetic equations for different initial concentrations at pH 2.0. The equilibrium amount adsorbed, equilibrium concentration and rate constant were calculated from better fitted pseudo second order kinetic plots for different initial concentrations. The equilibrium amount adsorbed (200 mg/g at 30 oC increased with the increase of temperature, indicated endothermic nature of the adsorption. The apparent activation energy of adsorption was determined from Arrhenius plot using pseudo second order rate constant and the value, Ea = 83.1 kJ/mol, revealed the process is chemisorption. Thermodynamic parameters: DHo, DGo and DSo, were determined from the equilibrium adsorption constant and the results obtained confirmed that the adsorption process was feasible, less spontaneous and endothermic. The equilibrium amount adsorbed was found to be increased with increase of solution pH from 2.0 to 6.0 indicating electrostatic interaction between cationic CV with anionic surface of UBTL dominated at higher pH due to the low zero point charge of pH of UBTL.

  13. Single-molecule enzymology of steroid transforming enzymes: Transient kinetic studies and what they tell us.

    Science.gov (United States)

    Penning, Trevor M

    2016-07-01

    Structure-function studies on steroid transforming enzymes often use site-directed mutagenesis to inform mechanisms of catalysis and effects on steroid binding, and data are reported in terms of changes in steady state kinetic parameters kcat, Km and kcat/Km. However, this dissection of function is limited since kcat is governed by the rate-determining step and Km is a complex macroscopic kinetic constant. Often site-directed mutagenesis can lead to a change in the rate-determining step which cannot be revealed by just reporting a decrease in kcat alone. These issues are made more complex when it is considered that many steroid transforming enzymes have more than one substrate and product. We present the case for using transient-kinetics performed with stopped-flow spectrometry to assign rate constants to discrete steps in these multi-substrate reactions and their use to interpret enzyme mechanism and the effects of disease and engineered mutations. We demonstrate that fluorescence kinetic transients can be used to measure ligand binding that may be accompanied by isomerization steps, revealing the existence of new enzyme intermediates. We also demonstrate that single-turnover reactions can provide a klim for the chemical step and Ks for steroid-substrate binding and that when coupled with kinetic isotope effect measurements can provide information on transition state intermediates. We also demonstrate how multiple turnover experiments can provide evidence for either "burst-phase" kinetics, which can reveal a slow product release step, or linear-phase kinetics, in which the chemical step can be rate-determining. With these assignments it becomes more straightforward to analyze the effects of mutations. We use examples from the hydroxysteroid dehydrogenases (AKR1Cs) and human steroid 5β-reductase (AKR1D1) to illustrate the utility of the approach, which are members of the aldo-keto reductase (AKR) superfamily.

  14. Combustion of furniture wood waste and solid wood: Kinetic study and evolution of pollutants

    OpenAIRE

    Moreno Caballero, Ana Isabel; Font Montesinos, Rafael; Conesa, Juan A.

    2017-01-01

    This work is focused on the combustion processes of wood waste. Two kinds of waste have been studied: furniture wood waste (treated and used wood) and solid wood from factories (untreated wood). A kinetic study has been carried out for each material in air and an N2:O2 9:1 atmosphere with dynamic and dynamic + isothermal runs at different heating rates, considering the decomposition of the three main components of the wood and also the combustion of the char obtained. Satisfactory kinetic mod...

  15. A kinetic study of lipase-catalyzed alcoholysis of palm kernel oil.

    Science.gov (United States)

    de Oliveira, D; Alves, T L

    2000-01-01

    The use of lipases as biocatalysts in interesterification reactions has been the object of growing interest, owing to the importance of esters as emulsifiers, intermediates to produce oleochemicals, and fuel alternatives. We consider in this article a kinetic study of lipase-catalyzed alcoholysis of palm kernel oil, using n-hexane as the solvent. In a first step the ester production was maximized by using a Taguchi design, and then an empirical model was built to determine the influence of the process variables. Taking into account the results obtained in the first step, we performed a kinetic study and developed a simple model for this system.

  16. Experimental and Modeling Study of Kinetics for Methane Hydrate Formation with Tetrahydrofuran as Promoter

    Institute of Scientific and Technical Information of China (English)

    Ning Zhengfu; Zhang Shixi; Zhang Qin; Zhen Shuangyi; Chen Guangjin

    2007-01-01

    The kinetics behavior of methane hydrate formation in the presence of tetrahydrofuran (THF) as promoter was studied. A set of experimental equipment was designed and constructed. A series of kinetics data for the formation of methane hydrate in the presence of THF were measured with the isochoric method. The influences of temperature,pressure and liquid flow rate on the methane consumption rate were studied respectively. Based on the Chen-Guo hydrate formation mechanism,a kinetics model for the formation of methane hydrate in the presence of THF by using the dimensionless Gibbs free energy difference of quasi-chemical reaction of basic hydrate formation,,as the driving force was proposed. The model was used to calculate the rate of methane consumption and it was shown that the calculated results were in good agreement with the experimental results.

  17. Copper adsorption on magnetite-loaded chitosan microspheres: A kinetic and equilibrium study

    Energy Technology Data Exchange (ETDEWEB)

    Podzus, P.E., E-mail: ppodzus@gmail.com [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Debandi, M.V. [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Daraio, M.E., E-mail: medit@fi.uba.ar [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina)

    2012-08-15

    A composite of Fe{sub 3}O{sub 4} nanoparticles and the biopolymer chitosan, chemically crosslinked, was prepared as microspheres and used to adsorb copper ions, which were chosen as a model of contaminant metal in water. The adsorption of copper on the magnetic microspheres was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 40 to 1100 ppm. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were well described by a pseudo-second-order kinetic model. It was found that the equilibrium data follow the Langmuir isotherm, with a maximum adsorption capacity of around 500 mg Cu/g chitosan. The used microspheres were removed and after desorption the material was able to be reused as an adsorbent. The prepared microspheres proved efficient in the removal of copper ions through an adsorption process whose kinetic and equilibrium characteristics were analyzed.

  18. A comparative study of teenage pregnancy.

    Science.gov (United States)

    Mahavarkar, S H; Madhu, C K; Mule, V D

    2008-08-01

    Teenage pregnancy is a global problem and is considered a high-risk group, in spite of conflicting evidence. Our objective was to compare obstetric outcomes of pregnancy in teenagers and older women. This was a retrospective study of case records of pregnancies from August 2000 to July 2001. Girls aged pregnancy outcomes in older women (19-35 years) in the same hospital. The study took place in the Government General Hospital, Sangli, India, a teaching hospital in rural India, with an annual delivery rate of over 3,500. A total of 386 teenage pregnancies were compared with pregnancies in 3,326 older women. Socioeconomic data, age, number of pregnancies, antenatal care and complications, mode of delivery, and neonatal outcomes were considered. The incidence of teenage pregnancy in the study was 10%. A significant proportion of teenage pregnant mothers were in their first pregnancies. The teenage mothers were nearly three times more at risk of developing anaemia (OR = 2.83, 95% CI = 2.2-3.7, p Teenage mothers were twice as likely to develop hypertensive problems in pregnancy (OR = 2.2, 95% CI = 1.5-3.2, p teenage pregnancies are still a common occurrence in rural India in spite of various legislations and government programmes and teenage pregnancy is a risk factor for poor obstetric outcome in rural India. Cultural practices, poor socioeconomic conditions, low literacy rate and lack of awareness of the risks are some of the main contributory factors. Early booking, good care during pregnancy and delivery and proper utilisation of contraceptive services can prevent the incidence and complications in this high-risk group.

  19. A calorimetric study of solute effects on the kinetic stability of a-amylase

    DEFF Research Database (Denmark)

    Olsen, Søren Nymand; Andersen, Kim Bruno; Øgendal, Lars Holm;

    2009-01-01

    In this study we evaluated the applications of isothermal titration calorimetry (ITC) to Study solute effects on the kinetics of irreversible protein denaturation. More specifically, denaturation of Bacillus Halmapalus alpha-amylase (BHA) was initiated by addition of EDTA to the calorimetric cell...

  20. Differences in kinetic variables between injured and noninjured novice runners : A prospective cohort study

    NARCIS (Netherlands)

    Bredeweg, Steef W.; Kluitenberg, Bas; Bessem, Bram; Buist, Ida

    2013-01-01

    Objectives: This prospective study examined differences in kinetic variables between injured and noninjured novice female and male runners and their potential contribution to RRIs. Design: A prospective cohort study. Methods: At baseline vertical ground reaction forces were assessed with an instrume

  1. Study growth kinetics in fluidized bed granulation with at-line FBRM.

    Science.gov (United States)

    Hu, Xinhui; Cunningham, John C; Winstead, Denita

    2008-01-22

    In this study, a novel at-line focused beam reflectance measurement (FBRM) technique was developed to investigate granule growth in a fluidized bed granulation (FBG). The chord length distribution (CLD) measured by the FBRM was used to represent granule particle size distribution (PSD). Through a systematic study, it was proved that the trends of the chord length measured by the at-line FBRM technique were identical to those measured by a laser diffraction instrument and sieve analysis in spite of different measurement mechanisms. The portable at-line FBRM technique was successfully applied to a granule growth kinetics study for a fluidized bed granulation performed in a Glatt GPCG-1 granulator. Granule size evolution was clearly exhibited by the at-line FBRM. Spray rate was found to be the most significant factor on the granule growth compared with the other two factors: binder solution concentration and intra- to extra-granular microcrystalline cellulose (MCC) ratio for the formulation studied in this work. The CLD evolution measured by the FBRM confirmed that the granule agglomeration was mainly dominated by the binder on the granule surface. The at-line FBRM enables us to select appropriate process parameters and effectively control the fluid bed granulation process.

  2. Dynamics and Kinetics Study of "In-Water" Chemical Reactions by Enhanced Sampling of Reactive Trajectories.

    Science.gov (United States)

    Zhang, Jun; Yang, Y Isaac; Yang, Lijiang; Gao, Yi Qin

    2015-11-12

    High potential energy barriers and engagement of solvent coordinates set challenges for in silico studies of chemical reactions, and one is quite commonly limited to study reactions along predefined reaction coordinate(s). A systematic protocol, QM/MM MD simulations using enhanced sampling of reactive trajectories (ESoRT), is established to quantitatively study chemical transitions in complex systems. A number of trajectories for Claisen rearrangement in water and toluene were collected and analyzed, respectively. Evidence was found that the bond making and breaking during this reaction are concerted processes in solutions, preferentially through a chairlike configuration. Water plays an important dynamic role that helps stabilize the transition sate, and the dipole-dipole interaction between water and the solute also lowers the transition barrier. The calculated rate coefficient is consistent with the experimental measurement. Compared with water, the reaction pathway in toluene is "narrower" and the reaction rate is slower by almost three orders of magnitude due to the absence of proper interactions to stabilize the transition state. This study suggests that the "in-water" nature of the Claisen rearrangement in aqueous solution influences its thermodynamics, kinetics, as well as dynamics.

  3. Comparative microscopy study of Vibrio cholerae flagella

    Science.gov (United States)

    Konnov, Nikolai P.; Baiburin, Vil B.; Zadnova, Svetlana P.; Volkov, Uryi P.

    1999-06-01

    A fine structure of bacteria flagella is an important problem of molecular cell biology. Bacteria flagella are the self-assembled structures that allow to use the flagellum protein in a number of biotechnological applications. However, at present, there is a little information about high resolution scanning probe microscopy study of flagellum structure, in particular, about investigation of Vibrio cholerae flagella. In our lab have been carried out the high resolution comparative investigation of V. cholerae flagella by means of various microscopes: tunneling (STM), scanning force (SFM) and electron transmission. As a scanning probe microscope is used designed in our lab versatile SPM with replaceable measuring heads. Bacteria were grown, fixed and treated according to the conventional techniques. For STM investigations samples were covered with Pt/Ir thin films by rotated vacuum evaporation, in SFM investigations were used uncovered samples. Electron microscopy of the negatively stained bacteria was used as a test procedure.

  4. Comparative studies on ecotoxicology of synthetic detergents.

    Science.gov (United States)

    Lal, H; Misra, V; Viswanathan, P N; Krishna Murti, C R

    1983-12-01

    To predict the comparative toxicological response of synthetic detergents on aquatic ecosystems, the effects of various concentrations of neutralized alkyl benzene sulfonate were studied. The median tolerance limit at 48 hr, 95% confidence limit, slope function, presumable harmless concentration, and rate of survival of different species of aquatic fauna such as water fleas (Daphnia magna), mosquito larvae (Culex pipiens), slug worms (Tubifex rivulorum), snails (Lymnaea vulgaris), tadpoles (Rana cyanophlyctis), and fish fingerlings (Cirrhina mrigala) were followed at 0, 24, 48, 72, and 96 hr. Any effect on quality of the water was also tested after the addition of various concentrations of detergents. The results showed that water fleas are more susceptible to detergent toxicity than fish fingerlings, tadpoles, slug worms, snails, and mosquito larvae. Behavioral changes were also observed as an index for detergent toxicity. The relative toxicity of the detergents to various species is discussed in relation to selective ecotoxicological response.

  5. A COMPARATIVE STUDY IN WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Hasan Al-Refai

    2014-02-01

    Full Text Available Sensor networks consist of a large number of small, low-powered wireless nodes with limited computation, communication, and sensing abilities, in a battery-powered sensor network, energy and communication bandwidth are a precious resources. Thus, there is a need to adapt the networking process to match the application in order to minimize the resources consumed and extend the life of the network. In this paper, we introduce a comparative study in different routing algorithms that propose vital solutions to the most important issues that should be taken into account when designing wireless network which are reliability, lifetime, communication bandwidth, transmission rand, and finally the limited energy issue, so we will introduce their algorithms and discuss how did they propose to solve such of these challenges and finally we will do some evaluation to each approach.

  6. Kinetic study of oxalic acid inhibition on enzymatic browning.

    Science.gov (United States)

    Son, S M; Moon, K D; Lee, C Y

    2000-06-01

    Oxalic acid has a strong antibrowning activity. The inhibitory pattern on catechol-PPO model system appeared to be competitive, with a K(i) value of 2.0 mM. When the PPO was incubated with oxalic acid, the activity was not recovered via dialysis, but the inactivated enzyme partially recovered its activity when cupric ion was added. Comparing the relative antibrowning effectiveness of oxalic acid with other common antibrowning agents, oxalic acid with I(50) value of 1.1 mM is as effective as kojic acid and more potent than cysteine and glutathione.

  7. Studies of Reaction Kinetics of Methane Hydrate Dissocation in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George J.; Seol, Yongkoo; Kneafsey, Timothy J.

    2005-03-10

    The objective of this study is the description of the kinetic dissociation of CH4-hydrates in porous media, and the determination of the corresponding kinetic parameters. Knowledge of the kinetic dissociation behavior of hydrates can play a critical role in the evaluation of gas production potential of gas hydrate accumulations in geologic media. We analyzed data from a sequence of tests of CH4-hydrate dissociation by means of thermal stimulation. These tests had been conducted on sand cores partially saturated with water, hydrate and CH4 gas, and contained in an x-ray-transparent aluminum pressure vessel. The pressure, volume of released gas, and temperature (at several locations within the cores) were measured. To avoid misinterpreting local changes as global processes, x-ray computed tomography scans provided accurate images of the location and movement of the reaction interface during the course of the experiments. Analysis of the data by means of inverse modeling (history matching ) provided estimates of the thermal properties and of the kinetic parameters of the hydration reaction in porous media. Comparison of the results from the hydrate-bearing porous media cores to those from pure CH4-hydrate samples provided a measure of the effect of the porous medium on the kinetic reaction. A tentative model of composite thermal conductivity of hydrate-bearing media was also developed.

  8. Study on Lumped Kinetic Model for FDFCC I. Establishment of Model

    Institute of Scientific and Technical Information of China (English)

    Wu Feiyue; Weng Huixin; Luo Shixian

    2008-01-01

    According to the process features and the reaction mechanism of FDFCC technology, its two reaction subsystems, one for heavy oil riser reactor, the other for gasoline riser reactor, were respectively studied. Correspondingly, a 12-lump kinetic model for heavy oil FCC and a 9-lump kinetic model for gasoline catalytic upgrading were presented. Based on this work, mathematical correlation of the lumps in the feeds and products involved in the reaction subsystems and those of the overall reaction system were analyzed in detail. Then, a combined kinetic model for FDFCC, which was based on the data recovered from a commercial unit, was put forward. The reaction performance embodied by the kinetic constants for the combined model of FDFCC was in accordance with catalytic cracking reaction mechanism. The model-calculated values were close to the data obtained in commercial scale. The model was easy to be applied in practice and could also provide some theoretical groundwork for further research on kinetic model for FDFCC.

  9. Study of kinetics of degradation of cyclohexane carboxylic acid by acclimated activated sludge.

    Science.gov (United States)

    Wang, Chunhua; Shi, Shuian; Chen, Hongyan

    2016-01-01

    Activated sludge contains complex microorganisms, which are highly effective biodegrading agents. In this study, the kinetics of biodegradation of cyclohexane carboxylic acid (CHCA) by an acclimated aerobic activated sludge were investigated. The results showed that after 180 days of acclimation, the activated sludge could steadily degrade >90% of the CHCA in 120 h. The degradation of CHCA by the acclimated activated sludge could be modeled using a first-order kinetics equation. The equations for the degradation kinetics for different initial CHCA concentrations were also obtained. The kinetics constant, kd, decreased with an increase in the CHCA concentration, indicating that, at high concentrations, CHCA had an inhibiting effect on the microorganisms in the activated sludge. The effects of pH on the degradation kinetics of CHCA were also investigated. The results showed that a pH of 10 afforded the highest degradation rate, indicating that basic conditions significantly promoted the degradation of CHCA. Moreover, it was found that the degradation efficiency for CHCA increased with an increase in temperature and concentration of dissolved oxygen under the experimental conditions.

  10. COSMOS - a study comparing peripheral intravenous systems.

    Science.gov (United States)

    López, Juan Luis González; Del Palacio, Encarnación Ferenández; Marti, Carmen Benedicto; Corral, Javier Olivares; Portal, Pilar Herrera; Vilela, Ana Arribi

    In many areas of the world, safety peripheral intravenous systems have come into widespread use. The Madrid region was the first in Spain to adopt such an approach. These systems, though initially introduced to protect users from sharps injuries, have now evolved to include patient protection features as well. Patient protection, simply stated, means closing the system to pathogen entry. The authors' purpose was to investigate, in a prospective and randomized study, the clinical performance of a closed safe intravenous system versus an open system (COSMOS - Compact Closed System versus Mounted Open System). COSMOS is designed to provide definitive answers, from a nursing perspective, to many topics related to peripheral venous catheterization, which have important implications in intravenous therapy and which have not been validated scientifically. Furthermore, it forms pioneering research in that it is the first clinical trial on medical devices in a legislated environment carried out entirely by nurses and whose promoter and principal investigator is a nurse. The objectives of COSMOS are to compare the effectiveness (as defined by time of survival without complications) and rates of catheter-related complications, such as phlebitis, pain, extravasation, blockage and catheter-related infections. It also looks at rates of catheter colonization, the ease of handling of both systems and overall costs. This article outlines the authors' approach, both in preparing hospital units for such an evaluation as well as in the choice of parameters and their method of study. Further articles will detail the results and findings of the study.

  11. Osteopathic manipulative treatment (OMT) effects on mandibular kinetics: kinesiographic study.

    Science.gov (United States)

    Monaco, A; Cozzolino, V; Cattaneo, R; Cutilli, T; Spadaro, A

    2008-03-01

    The aim of this study was to evaluate the effects of Osteopathic Manipulative Treatment (OMT) on mandibular kinematics in TMD patients. The study was conduced on 28 children with non-specific TMD symptoms, limited mouth opening, history of trauma (delivery trauma, accident trauma). Patients were randomly divided into two groups: an OMT group (study group) and a no-intervention group (control group). All subjects underwent a first kinesiographic recording to evaluate the amplitude and velocity of maximal opening-closing movements. Study group patients underwent a second kinesiographic recording 2 months after OMT. Control group patients were submitted to a control kinesiographic recording six months after the first one. Kinesiographic tracings were acquired using the K7I system. The kinesiographic data of the study group showed a moderate statistically significant difference (pOMT can induce changes in the stomatognathic dynamics, offering a valid support in the clinical approach to TMD. Multifactorial genesis of chronic disorders is also confirmed.

  12. Sorption of methylene blue on treated agricultural adsorbents: equilibrium and kinetic studies

    Science.gov (United States)

    Tiwari, D. P.; Singh, S. K.; Sharma, Neetu

    2015-03-01

    Agricultural adsorbents are reported to have a remarkable performance for adsorption of dyes. In the present study, formaldehyde and sulphuric acid treated two agricultural adsorbents; potato peel and neem bark are used to adsorb methylene blue. On the whole, the acid-treated adsorbents are investigated to have high sorption efficiency compared to HCHO treated adsorbents. The percentage removal efficiency of H2SO4 treated potato peel (APP) increases considerably high from 75 to 100 % with increase in adsorbent dose, whereas the removal efficiency of H2SO4 treated neem bark (ANB) is found to be 98 % after adding the first dose only. The monolayer sorption behaviour of HCHO treated potato peel (PP) and APP is well defined by Langmuir, whereas the chemisorptions behaviour of HCHO treated neem bark (NB) and ANB is suggested by Temkin's isotherm model. The maximum adsorption capacity measured is highest in ANB followed by NB, PP and APP with the values of 1000, 90, 47.62 and 40.0 mg/g, respectively. The pseudo-second-order kinetic model fitted well with the observed data of all the four adsorbents. The results obtained reveal that NB and ANB both are good adsorbents compared to PP and APP.

  13. Kinetic Study on Flooded Soil Recovery Using Soil Containing Arbuscular Mycorrhizal Fungi

    Directory of Open Access Journals (Sweden)

    Zainol N.

    2016-01-01

    Full Text Available The purpose of this research was to determine the kinetic parameters for flooded soil recovery via soil containing Arbuscular Mycorrhizal fungi (AMF. The general procedures of this experiment started by preparation of simulated flooded soil (FS and soil containing AMF (SA. Mixed soil was prepared by mixing FS and SA with ratio 1:1. Onion plant was chosen as a host plant and planted in the mixed soil for 14 days. The plantation was conducted in ambient temperature. The nutrients (nitrogen, phosphorus and potassium concentrations in the soil were tested using HACH Spectrophotomer. The Michaelis-Menten equation was used to study the nutrients recovery in soil. The Lineweaver-Bulk plot was used to solve the Michaelis-Menten equation. From the experiment conducted, the maximum nutrient uptake (Vmax and bonding affinity (Km obtained for nitrogen (N were 6.28mg/l.d and 82.17 mg/l, for phosphorus (P were 9.80 mg/l.d and 60.96 mg/l.d and for potassium (K were 0.07mg/l.d and 4.55mg/l. By comparing the result with other researcher, it showed that the Vmax and Km of nitrogen (N and phosphorus (P obtained were higher than other research. This was because the onion required a high level of N and P in the soil compared to other host plant.

  14. Comparison of Parameter Estimations Using Dual-Input and Arterial-Input in Liver Kinetic Studies of FDG Metabolism.

    Science.gov (United States)

    Cui, Yunfeng; Bai, Jing

    2005-01-01

    Liver kinetic study of [18F]2-fluoro-2-deoxy-D-glucose (FDG) metabolism in human body is an important tool for functional modeling and glucose metabolic rate estimation. In general, the arterial blood time-activity curve (TAC) and the tissue TAC are required as the input and output functions for the kinetic model. For liver study, however, the arterial-input may be not consistent with the actual model input because the liver has a dual blood supply from the hepatic artery (HA) and the portal vein (PV) to the liver. In this study, the result of model parameter estimation using dual-input function is compared with that using arterial-input function. First, a dynamic positron emission tomography (PET) experiment is performed after injection of FDG into the human body. The TACs of aortic blood, PV blood, and five regions of interest (ROIs) in liver are obtained from the PET image. Then, the dual-input curve is generated by calculating weighted sum of both the arterial and PV input curves. Finally, the five liver ROIs' kinetic parameters are estimated with arterial-input and dual-input functions respectively. The results indicate that the two methods provide different parameter estimations and the dual-input function may lead to more accurate parameter estimation.

  15. Kinetic Study of Acetone-Butanol-Ethanol Fermentation in Continuous Culture.

    Science.gov (United States)

    Buehler, Edward A; Mesbah, Ali

    2016-01-01

    Acetone-butanol-ethanol (ABE) fermentation by clostridia has shown promise for industrial-scale production of biobutanol. However, the continuous ABE fermentation suffers from low product yield, titer, and productivity. Systems analysis of the continuous ABE fermentation will offer insights into its metabolic pathway as well as into optimal fermentation design and operation. For the ABE fermentation in continuous Clostridium acetobutylicum culture, this paper presents a kinetic model that includes the effects of key metabolic intermediates and enzymes as well as culture pH, product inhibition, and glucose inhibition. The kinetic model is used for elucidating the behavior of the ABE fermentation under the conditions that are most relevant to continuous cultures. To this end, dynamic sensitivity analysis is performed to systematically investigate the effects of culture conditions, reaction kinetics, and enzymes on the dynamics of the ABE production pathway. The analysis provides guidance for future metabolic engineering and fermentation optimization studies.

  16. Kinetic Study of Acetone-Butanol-Ethanol Fermentation in Continuous Culture

    Science.gov (United States)

    Buehler, Edward A.; Mesbah, Ali

    2016-01-01

    Acetone-butanol-ethanol (ABE) fermentation by clostridia has shown promise for industrial-scale production of biobutanol. However, the continuous ABE fermentation suffers from low product yield, titer, and productivity. Systems analysis of the continuous ABE fermentation will offer insights into its metabolic pathway as well as into optimal fermentation design and operation. For the ABE fermentation in continuous Clostridium acetobutylicum culture, this paper presents a kinetic model that includes the effects of key metabolic intermediates and enzymes as well as culture pH, product inhibition, and glucose inhibition. The kinetic model is used for elucidating the behavior of the ABE fermentation under the conditions that are most relevant to continuous cultures. To this end, dynamic sensitivity analysis is performed to systematically investigate the effects of culture conditions, reaction kinetics, and enzymes on the dynamics of the ABE production pathway. The analysis provides guidance for future metabolic engineering and fermentation optimization studies. PMID:27486663

  17. KINETIC STUDY OF THE ENZYME CONVERSION OF STEAM EXPLODED PAULOWNIA TOMENTOSA TO GLUCOSE

    Directory of Open Access Journals (Sweden)

    Greta Radeva,

    2011-11-01

    Full Text Available Paulownia Tomentosa was pretreated by steam explosion. The cellulase complex NS 50013 and the β-glucosidase NS 50010 of Novozymes AS were used for the enzymatic conversion of cellulose to glucose. The kinetics of enzyme conversion was studied using the exponential kinetic equation valid for processes taking place at uniformly inhomogeneous surfaces. The kinetic coefficient of inhomogeneity accounts for the energy and entropy inhomogeneity of the system and depends on the temperature. It was established that both the activation energy and the pre-exponential factor increase simultaneously with increasing of conversion degree. A compensation effect between pre-exponential factor and activation energy was observed. The energetic hindrances established cannot be completely compensated by the positive effect of the pre-exponential factor increase. Hence, the activation energy has a determining influence on how quickly the rate of hydrolysis decreases.

  18. KINETIC AND MECHANISTIC STUDY OF OXIDATION OF ATENOLOL BY CERIUM (IV IN SULPHURIC ACIDIC MEDIUM

    Directory of Open Access Journals (Sweden)

    Fadnis G Anand

    2012-03-01

    Full Text Available The kinetics of oxidation of antihypertensive drug, atenolol by cerium (IV in sulphuric acidic medium has been studied spectrophotometrically at 360 nm. The reaction between cerium (IV and atenolol in acidic medium has exhibited 2:1 stoichiometry. The order of the reaction with respect to atenolol has been found to be one. The observed pseudo first order rate constants kobs increased with sulphuric acid and hydrogen ion concentrations where as decreased bisulphate ion concentration indicating the formation bisulphato reactive species of cerium (IV in the present reaction. The thermodynamic parameters have been evaluated from the temperature variation kinetic data. A possible mechanism is proposed which has been validated by derived rate law. An attempt has been made to use rate data for kinetic estimation of atenolol.KEYWORDS:

  19. A kinetic study of textile dyeing wastewater degradation by Penicillium chrysogenum.

    Science.gov (United States)

    Durruty, Ignacio; Fasce, Diana; González, Jorge Froilán; Wolski, Erika Alejandra

    2015-06-01

    The potential of Penicillium chrysogenum to decolorize azo dyes and a real industrial textile wastewater was studied. P. chrysogenum was able to decolorize and degrade three azo dyes (200 mg L(-1)), either independently or in a mixture of them, using glucose as a carbon source. A kinetic model for degradation was developed and it allowed predicting the degradation kinetics of the mixture of the three azo dyes. In addition, P. chrysogenum was able to decolorize real industrial wastewater. The kinetic model proposed was also able to predict the decolorization of the real wastewater. The calibration of the proposed model makes it a useful tool for future wastewater facilities' design and for practical applications.

  20. A kinetics modeling study on the inhibition of glucose on cellulosome of Clostridium thermocellum.

    Science.gov (United States)

    Zhang, Pengcheng; Wang, Buyun; Xiao, Qunfang; Wu, Shan

    2015-08-01

    A simplified kinetics model was built to study the inhibition of glucose on cellulosome of Clostridium thermocellum. Suitable reaction conditions were adopted to evaluate the model. The model was evaluated at different temperatures and further with various activated carbon additions as adsorbent for glucose. Investigation results revealed that the model could describe the hydrolysis kinetics of cellulose by cellulosome quite well. Glucose was found to be an inhibitor for cellulosome based on the kinetics analysis. Inhibition increased with the increase in temperature. Activated carbon as adsorbent could lower the inhibition. Parameters in the model were further discussed based on the experiment. The model might also be used to describe the strong inhibition of cellobiose on cellulosome. Saccharification of cellulose by both cellulosome and C. thermocellum could be enhanced efficiently by activated carbon addition.

  1. A study of static, kinetic, and dynamic visual acuity in 102 Japanese professional baseball players

    Directory of Open Access Journals (Sweden)

    Hoshina K

    2013-03-01

    Full Text Available Kohji Hoshina,1 Yuichi Tagami,2 Osamu Mimura,3 Hiroshi Edagawa,4 Masao Matsubara,5 Teiichi Nakayama6 1Hoshina Eye Clinic, Nishinomiya, Japan; 2Department of Ophthalmology, Kobe Century Memorial Hospital, Kobe, Japan; 3Department of Ophthalmology, Hyogo College of Medicine, Nishinomiya, Japan; 4Edagawa Eye Clinic, Tokyo, Japan; 5Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan; 6Ritsumeikan University, Kyoto, Japan Background: It seemed that visual functions might have some effects on the performance of baseball players. We measured static, kinetic, and dynamic visual acuity (SVA, KVA, and DVA, respectively of Japanese professional baseball players to ascertain whether there would be any difference in SVA, KVA, and DVA among player groups stratified according to their performance level. Methods: The subjects were 102 male professional baseball players with a mean age of 26 years who were members of a Japanese professional baseball club from 2000 to 2009. They were stratified into three groups according to their performance level: A (players who were on the roster of the top-level team all the time throughout the study period, B (players who were on the roster of the top-level team sometimes but not all the time, and C (players who were never on the roster of the top-level team. They were interviewed for the use of corrective visual aids, and examined for SVA, KVA, and DVA. The measurements of these parameters were compared among groups A, B, and C. We also investigated and analyzed the association of KVA or DVA with player position (pitchers or fielders and with hand dominance for batting. KVA was compared between the pitchers and the fielders because they each require different playing skills. DVA was compared between the right-handed and the left-handed batters. Results: There was no statistically significant difference among groups A, B, and C. There was a statistically significant difference in

  2. Kinetic Monte Carlo Studies of Hydrogen Abstraction from Graphite

    CERN Document Server

    Cuppen, H M

    2008-01-01

    We present Monte Carlo simulations on Eley-Rideal abstraction reactions of atomic hydrogen chemisorbed on graphite. The results are obtained via a hybrid approach where energy barriers derived from density functional theory calculations are used as input to Monte Carlo simulations. By comparing with experimental data, we discriminate between contributions from different Eley-Rideal mechanisms. A combination of two different mechanisms yields good quantitative and qualitative agreement between the experimentally derived and the simulated Eley-Rideal abstraction cross sections and surface configurations. These two mechanisms include a direct Eley-Rideal reaction with fast diffusing H atoms and a dimer mediated Eley-Rideal mechanism with increased cross section at low coverage. Such a dimer mediated Eley-Rideal mechanism has not previously been proposed and serves as an alternative explanation to the steering behavior often given as the cause of the coverage dependence observed in Eley-Rideal reaction cross sect...

  3. Kinetics Study of Balanites Aegyptiaca Oil Transesterification for the ...

    African Journals Online (AJOL)

    User-PC

    ABSTRACT: In this study, transesterification of Balanites aegyptiaca oil employing a homogeneous catalyst ... However, separation of the catalyst and purification of the ... ratio, presence of FFA's and water, as well as pressure, agitation speed ...

  4. Kinetic study of the complexation of gallic acid with Fe(II)

    Science.gov (United States)

    Lu, Li-li; Li, Ying-hua; Lu, Xiu-yang

    2009-10-01

    Kinetic study on the complexation of gallic acid with ferrous sulfate was performed using UV-Vis absorption spectroscopy. Under the experimental conditions, the stoichiometric composition of the formed complex is 1:1. The complexation reaction was found to be a second-order one. The influences of temperature, ionic strength and solvents on the complexation reaction were investigated. According to the Arrhenius equation, the apparent activation energy of the complexation reaction was evaluated to be 71.64 kJ × mol -1. A three-step reaction mechanism was proposed, which can well explain the kinetic results obtained.

  5. STUDY ON THE KINETICS OF POLYMERIZATION OF MMA BY COPPER(Ⅱ) CHELATING RESINS

    Institute of Scientific and Technical Information of China (English)

    WangHongzuo; JiangYuanzhang; 等

    1993-01-01

    The polymerization of MMA initiated by copper(Ⅱ) chelating resins/CCl4 system was studied.From the kinetic data,the kinetic equation of polymerization can be expressed as Rp=Ke-56400/RT[MMA]1.57[CCl4]m[RESIN-Cu]0.18 where m:3-4.5,when[CCl4] 0.1-6.93M.The free radical polymerization mechanism is proposed.The primary radicals are formed by the process of complexation-chlorine transformation among the copper(Ⅱ) chelating resin,CCl4 and methacrylate.

  6. Kinetic Study on Ultrasound Assisted Biodiesel Production from Waste Cooking Oil

    Directory of Open Access Journals (Sweden)

    Widayat

    2015-09-01

    Full Text Available The objective of this research was to study a kinetic model of biodiesel production from waste cooking oil assisted by ultrasound power. The model considered the biodiesel production process as a 2nd order reversible reaction, while its kinetic parameters were estimated using MATLAB, based on data extracted from Hingu, et al. [1]. The data represented experiments under low-frequency ultrasonic wave (20 kHz and variations of temperature, power, catalyst concentration, and alcohol-oil molar ratio. Statistical analysis showed that the proposed model fits well to the experimental data with a determination coefficient (R2 higher than 0.9.

  7. Kinetic studies of novel inhibitors of endomorphin degrading enzymes

    OpenAIRE

    Perlikowska, Renata; Fichna, Jakub; do-Rego, Jean Claude; Gach, Katarzyna; Janecka, Anna

    2011-01-01

    Endomorphins (EMs), two endogenous μ-opioid receptor selective ligands, are attractive lead compounds for opioid-based pain management studies. However, these peptides are quickly degraded by peptidases, in particular by dipeptidylpeptidase IV (DPP IV) and aminopeptidase M (APM). Targeting enzymatic degradation is one approach to prolong endomorphin activity. In this study we characterized the action of two new inhibitors of similar to endomorphins structure, Tyr-Pro-Ala-NH2 (EMDB-2) and Tyr-...

  8. Intentional burns in Nepal: a comparative study.

    Science.gov (United States)

    Lama, Bir Bahadur; Duke, Janine M; Sharma, Narayan Prasad; Thapa, Buland; Dahal, Peeyush; Bariya, Nara Devi; Marston, Wendy; Wallace, Hilary J

    2015-09-01

    Intentional burns injuries are associated with high mortality rates, and for survivors, high levels of physical and psychological morbidity. This study provides a comprehensive assessment of intentional burn admissions to the adult Burns Unit at Bir Hospital, Kathmandu, Nepal, during the period 2002-2013. A secondary data analysis of de-identified data of patients hospitalized at Bir Hospital, Kathmandu, with a burn during the period of 1 January 2002 to 31 August 2013. Socio-demographic, injury and psychosocial factors of patients with intentional and unintentional burns are described and compared. Chi-square tests, Fisher's exact test and Wilcoxon rank sum tests were used to determine statistical significance. There were a total of 1148 burn admissions of which 329 (29%) were for intentional burn, 293 (26%) were self-inflicted and 36 (3%) were due to assault. Mortality rates for intentional burns were approximately three times those for unintentional burns (60 vs. 22%). When compared to unintentional burns, patients with intentional burns were more likely to be female (79 vs. 48%), married (84 vs. 67%), younger (25 vs. 30 years), have more extensive burns (total body surface area, %: 55 vs. 25) and higher mortality (60 vs. 22%). Intentional burns were more likely to occur at home (95 vs. 67%), be caused by fire (96 vs. 77%), and kerosene was the most common accelerant (91 vs. 31%). A primary psychosocial risk factor was identified in the majority of intentional burn cases, with 60% experiencing adjustment problems/interpersonal conflict and 32% with evidence of a pre-existing psychological condition. A record of alcohol/substance abuse related to the patient or other was associated with a greater proportion of intentional burns when compared with unintentional burns (17 vs. 4%). The majority of intentional burn patients were female. Almost all intentional burns occurred in the home and were caused by fire, with kerosene the most common accelerant used. Underlying

  9. Quartz crystal microbalance study of the kinetics of surface initiated polymerization

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Surface initiated polymerization (SIP) is a valuable tool in synthesizing functional polymer brushes,yet the kinetic understanding of SIP lags behind the development of its application. We apply quartz crystal microbalance (QCM) to address two issues that are not fully addressed yet play a central role in the rational design of functional polymer brushes,namely quantitative determination of the kinetics and the initiator efficiency (IE) of SIP. SIP are monitored online using QCM. Two quantitative frequencythickness (f-T) relations make the direct determination and comparison of the rate of polymerization possible even for different monomers. Based on the bi-termination model,the kinetics of SIP is simply described by two variables,which are related to two polymerization constants,namely a = 1/(kp,s,app-[M][R·]0) and b = kt,s,app/(kp,s,app[M]). Factors that could alter the kinetics of SIP are studied,including (i) the molecular weight of monomers,(ii) the solvent used,(iii) the initial density of the initiator,(iv) the concentration of monomer,[M],and (v) the catalyst system (ratio among the ingredients,metal,ligands,and additives). The dynamic nature of IE is also described by these two variables,IE = a/(a + bt). Instead of the molecular weight and the polydispersity,we suggest that film thickness,the two kinetic parameters (a and b),and the initial density of the initiator and IE be the parameters that characterize ultrathin polymer brushes. Besides the kinetics study of SIP,the reported method has many other applications,for example,in the fast screening of catalyst system for SIP and other polymerization systems.

  10. Modeling and comparative study of fluid velocities in heterogeneous rocks

    Science.gov (United States)

    Hingerl, Ferdinand F.; Romanenko, Konstantin; Pini, Ronny; Balcom, Bruce; Benson, Sally

    2013-04-01

    permeabilities were then correlated with the ones based on the porosity maps and the Kozeny-Carman relationship. The findings of the comparative modeling study are discussed and its potential impact on the modeling of fluid residence times and kinetic reaction rates of fluid-rock interactions in rocks containing meso-scale heterogeneities are reviewed.

  11. Kinetic studies on the reaction between dicyanocobinamide and hypochlorous acid.

    Directory of Open Access Journals (Sweden)

    Dhiman Maitra

    Full Text Available Hypochlorous acid (HOCl is a potent oxidant generated by myeloperoxidase (MPO, which is an abundant enzyme used for defense against microbes. We examined the potential role of HOCl in corrin ring destruction and subsequent formation of cyanogen chloride (CNCl from dicyanocobinamide ((CN2-Cbi. Stopped-flow analysis revealed that the reaction consists of at least three observable steps, including at least two sequential transient intermediates prior to corrin ring destruction. The first two steps were attributed to sequential replacement of the two cyanide ligands with hypochlorite, while the third step was the destruction of the corrin ring. The formation of (OCl(CN-Cbi and its conversion to (OCl2-Cbi was fitted to a first order rate equation with second order rate constants of 0.002 and 0.0002 µM(-1 s(-1, respectively. The significantly lower rate of the second step compared to the first suggests that the replacement of the first cyanide molecule by hypochlorite causes an alteration in the ligand trans effects changing the affinity and/or accessibility of Co toward hypochlorite. Plots of the apparent rate constants as a function of HOCl concentration for all the three steps were linear with Y-intercepts close to zero, indicating that HOCl binds in an irreversible one-step mechanism. Collectively, these results illustrate functional differences in the corrin ring environments toward binding of diatomic ligands.

  12. Kinetics Study of Balanites Aegyptiaca Oil Transesterification for the ...

    African Journals Online (AJOL)

    User-PC

    In this study, transesterification of Balanites aegyptiaca oil employing a homogeneous ... some time due to being green, non-toxic, ... usually: vegetable oil, animal fat and used cooking oil. The triglyceride would be treated ... silica are some of the solids acid/base catalyst .... glycerol, CH3OH and remaining NaOH or HCl.

  13. A Kinetic Study of the Emulsion Polymerization of Vinyl Acetate

    DEFF Research Database (Denmark)

    Friis, N.; Nyhagen, L.

    1973-01-01

    The emulsion polymerization of vinyl acetate was studied at 50°C. It was found that the rate of polymerization was proportional to the 0.5 power of the initiator concentration and the 0.25 power of the number of particles. The number of particles was proportional to the power 0.5 ± 0.05 of the em...

  14. Theoretical Studies in Chemical Kinetics - Annual Report, 1970.

    Science.gov (United States)

    Karplus, Martin

    1970-10-01

    The research performed includes (a) Alkali-Halide, Alkali-Halide (MX, M’X’) Exchange Reactions; (b) Inversion Problem; (c) Quantum Mechanics of Scattering Processes, (d) Transition State Analysis of Classical Trajectories, (e) Differential Cross Sections from Classical Trajectories; and (f) Other Studies.

  15. A kinetic study of precipitation from supersaturated calcium phosphate solutions

    NARCIS (Netherlands)

    Kemenade, M.J.J.M. van; Bruyn, P.L. de

    The formation of three different crystalline calcium phosphates (DCPD, OCP, HAP) and an amorphous calcium phosphate was studied as a function of pH and supersaturation. Under the experimental conditions the formation of HAP is always found to be preceded by one or more precursors in a sequence that

  16. The BEST study - a prospective study to compare business class ...

    African Journals Online (AJOL)

    ... a prospective study to compare business class versus economy class air travel as a cause of thrombosis. ... Patients/methods. ... Logistical regression analysis was used to determine the risk factors related to abnormally high D-dimer levels.

  17. Kinetic Studies on Forming Iso-nuclear -type Chelates of Rare Earths with p-Sulphoaminobromophosphonazo

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The kinetic behavior of forming the iso-nuclear b -type chelates of rare earth ions (RE3+) with p-sulphoaminobromophosphonazo (BPA-pSN) in ClCH2COOH-CH3COONa buffer solutions were studied by a spectrophotometric method.

  18. Green chemicals : A Kinetic Study on the Conversion of Glucose to Levulinic Acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L.P.B.M.; Heeres, H.J.

    2006-01-01

    Levulinic acid has been identified as a promising green, biomass derived platform chemical. A kinetic study on one of the key steps in the conversion of biomass to levulinic acid, i.e., the acid catalysed decomposition of glucose to levulinic acid has been performed. The experiments were performed i

  19. You Are What You Eat: Mass spectrometry in paediatric kinetic studies using stable isotopes

    NARCIS (Netherlands)

    H. Schierbeek (Henk)

    2009-01-01

    textabstractAn overview will be presented about applications of stable isotopes in paediatric research. Mass spectrometry has proven to be an essential tool for unravelling kinetic studies in a large range of different research disciplines related to intestinal diseases, obesities, severe cerebral p

  20. A kinetic study on the conversion of glucose to levulinic acid

    NARCIS (Netherlands)

    Girisuta, B; Janssen, LPBM; Heeres, HJ

    2006-01-01

    Levulinic acid has been identified as a promising green. biomass derived platform chemical. A kinetic study oil one of the key steps in the conversion of biomass to levulinic acid, i.e., the acid catalysed decomposition of glucose to levulinic acid has been performed. The experiments were Performed

  1. Kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid

    NARCIS (Netherlands)

    Girisuta, B.; Janssen, L. P. B. M.; Heeres, H. J.

    2007-01-01

    A variety of interesting bulk chemicals is accessible by the acid-catalyzed hydrolysis of cellulose. An interesting example is levulinic acid, a versatile precursor for fuel additives, polymers, and resins. A detailed kinetic study on the acid-catalyzed hydrolysis of cellulose to levulinic acid is

  2. In situ study of equilibrium phenomena and kinetics in a BiSCCO Ag tape

    DEFF Research Database (Denmark)

    Poulsen, H.F.; Andersen, L.G.; Frello, T.;

    1999-01-01

    Structural changes during the annealing of a mono-filament BiSCCO/Ag tape in air are monitored in situ by synchrotron X-ray diffraction. Starting at 750 degrees C, a very slow ramp rate is used, followed by high temperature cycling to study equilibrium phenomena and kinetics. For the first time...

  3. Kinetic modelling in food science : a case study on chlorophyll degradation in olives

    NARCIS (Netherlands)

    Boekel, van M.A.J.S.

    2000-01-01

    This paper critically reviews the use of kinetics in modelling (bio)chemical changes in foods. Multiresponse modelling (taking more reactants and products of the reaction under study into consideration in the modelling process) is advocated as opposed to uniresponse modelling (in which only one

  4. A kinetic study of 1,3-dipolar cycloadditions in micellar media

    NARCIS (Netherlands)

    Rispens, T; Engberts, JBFN

    2003-01-01

    The kinetics of the 1,3-dipolar cycloadditions (DC) of benzonitrile oxide with a series of N-substituted maleimides in micellar media have been investigated. Surfactants studied include anionic sodium dodecyl sulfate, cationic cetyltrimethylammonium bromide, and a series of nonionic alkyl poly(ethyl

  5. The Nature of the Micellar Stern Region As Studied by Reaction Kinetics. 2

    NARCIS (Netherlands)

    Buurma, Niklaas J.; Serena, Paola; Blandamer, Michael J.; Engberts, Jan B.F.N.

    2004-01-01

    The nature of rate-retarding effects of cationic micelles on the water-catalyzed hydrolyses of a series of para-substituted 1-benzoyl-1,2,4-triazoles (1a-f) and 1-benzoyl-3-phenyl-1,2,4-triazole (2) has been studied using kinetic methods. A comparison is drawn between medium effects in the micellar

  6. The renneting of milk : a kinetic study of the enzymic and aggregation reactions

    NARCIS (Netherlands)

    Hooydonk, van A.C.M.

    1987-01-01

    The rennet-induced clotting of milk was studied under various conditions. The kinetics of the enzymic and aggregation reactions was analysed separately and, where possible, related to the physico-chemical properties of the casein micelle and its environment.

    The effects of important

  7. The kinetics of the methanol synthesis on a copper catalyst: An experimental study

    NARCIS (Netherlands)

    Bos, A.N.R.; Borman, P.C.; Kuczynski, M.; Westerterp, K.R.

    1989-01-01

    The kinetics of the low pressure of methanol from feed gases containing solely CO and H2 were studied in an internally recycled gradientless reactor. As experimental accuracy impeded the application of high CO contents, the experimental range of mole fraction of CO was limited to 0.04 to 0.22. The

  8. Kinetic Study of the Reaction between Tert-butyl Hydrazine and Nitrous Acid

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The kinetic study of the reaction between tert-butyl hydrazine(TBH)and nitrous acid in nitric acid system is performed by spectrophotometry. The effect of some factors such as the concentration of TBH, the concentration of nitric acid, ionic strength, temperature and the

  9. Study on Curing Kinetics of Heat-resistant Flexible Polyamide Modified Epoxy Resin Adhesive

    Directory of Open Access Journals (Sweden)

    Hua Li

    2015-04-01

    Full Text Available In order to study the effects of numerous variables affecting the reaction rate of heat-resistant flexible modified epoxy resin adhesive, the curing kinetics of polyamide modified epoxy resin was studied. The heat-resistant flexible modified epoxy resin adhesive cured at room-temperature was prepared with epoxy resin, polysulfide rubber and organosilicone as adhesive component, polyamide as main curing agent and addition of different modified filler and the curing agent containing benzene ring structure. The curing kinetics of polyamide modified epoxy resin was studied by Differential Scanning Calorimetry (DSC at different heating speeds and the characteristic temperatures of the curing process were analyzed and confirmed. the kinetics parameters of activation energy was calculated using Flynn-Wall-Ozawa equation and Kissinger equation, respectively, then the kinetic model of curing reaction was built as d&alpha/dt = 4.38×107 exp (-57740/RT (1-&alpha0.93, the results show that the two-parameter model is adequate to represent the curing reaction process, the model can well describe the curing reaction process of the studied resin. The DSC curves obtained using the experimental data show a good agreement with that theoretically calculated. The research results will provide theoretical basis for the choice of manufacturing process and the optimization of processing window.

  10. Kinetic Study of the Chemical Vapor Deposition of Tantalum in Long Narrow Channels

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Petrushina, Irina

    2016-01-01

    A kinetic study of the chemical vapor deposition of tantalum in long narrow channels is done to optimize the industrial process for the manufacture of tantalum coated plate heat exchangers. The developed model fits well at temperatures between 750 and 850 °C, and in the pressure range of25–990 mb...

  11. Impact of contamination with long-lived radionuclides on PET kinetics modelling in multitracer studies

    DEFF Research Database (Denmark)

    Jødal, Lars; Hansen, Søren Baarsgaard; Jensen, Svend B

    2016-01-01

    Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long-lived contamin...

  12. Kinetic studies of sulfide mineral oxidation and xanthate adsorption

    Science.gov (United States)

    Mendiratta, Neeraj K.

    2000-10-01

    Sulfide minerals are a major source of metals; however, certain sulfide minerals, such as pyrite and pyrrhotite, are less desirable. Froth flotation is a commonly used separation technique, which requires the use of several reagents to float and depress different sulfide minerals. Xanthate, a thiol collector, has gained immense usage in sulfide minerals flotation. However, some sulfides are naturally hydrophobic and may float without a collector. Iron sulfides, such as pyrite and pyrrhotite, are few of the most abundant minerals, yet economically insignificant. Their existence with other sulfide minerals leads to an inefficient separation process as well as environmental problems, such as acid mine drainage during mining and processing and SO 2 emissions during smelting process. A part of the present study is focused on understanding their behavior, which leads to undesired flotation and difficulties in separation. The major reasons for the undesired flotation are attributed to the collectorless hydrophobicity and the activation with heavy metal ions. To better understand the collectorless hydrophobicity of pyrite, Electrochemical Impedance Spectroscopy (EIS) of freshly fractured pyrite electrodes was used to study the oxidation and reduction of the mineral. The EIS results showed that the rate of reaction increases with oxidation and reduction. At moderate oxidizing potentials, the rate of reaction is too slow to replenish hydrophilic iron species leaving hydrophobic sulfur species on the surface. However, at higher potentials, iron species are replaced fast enough to depress its flotation. Effects of pH and polishing were also explored using EIS. Besides collectorless hydrophobicity, the activation of pyrrhotite with nickel ions and interaction with xanthate ions makes the separation more difficult. DETA and SO2 are commonly used as pyrrhotite depressants; however, the mechanism is not very well understood. Contact angle measurements, cyclic voltammetry and Tafel

  13. COMPARATIVE STUDY ON ACCOUNTING AND FISCAL AMORTIZATION

    Directory of Open Access Journals (Sweden)

    MARIANA GURAU

    2012-05-01

    Full Text Available Placed in the international trend, Romanian accounting had experienced various changes, especially as regards of progress on disconnection between accounting and fiscality. In the present, fiscal rules should not have any role in accounting decisions, because accounting rules are applied to produce accounting information that is useful in making decisions and to provide a "true and fair view" upon financial reality of the entity. However, the barrier in the habit of accounting to thinking for fiscal point of view all economic transactions remains insurmountable, yet. Starting from this perspective on disconnection between accounting and fiscality would mean that amortization recorded in the accounting, as a result of management policy, to be different from fiscality amortization, to calculate income tax. Although formally accepted, disconnect between accounting and fiscality continues to meet many difficulties. In this sense, it is usual in practice to use the same method of amortization for accounting purposes and for fiscal purposes to prevent complications of double track amortization and prevent wandering in the rules in this field. Accounting rule is deliberately eluded in favor of the fiscal rules. This is the reason we proposed to make in this paper a comparative study between norms and rules on accounting and fiscal amortization, paper in which we intend to show the benefits of applying accounting and fiscal rules separately.

  14. Comparative study of selected parallel tempering methods

    Science.gov (United States)

    Malakis, A.; Papakonstantinou, T.

    2013-07-01

    We review several parallel tempering schemes and examine their main ingredients for accuracy and efficiency. The present study covers two selection methods of temperatures and several choices for the exchange of replicas, including a recent novel all-pair exchange method. We compare the resulting schemes and measure specific heat errors and efficiency using the two-dimensional (2D) Ising model. Our tests suggest that an earlier proposal for using numbers of local moves related to the canonical correlation times is one of the key ingredients for increasing efficiency, and protocols using cluster algorithms are found to be very effective. Some of the protocols are also tested for efficiency and ground state production in 3D spin-glass models where we find that a simple nearest-neighbor approach using a local n-fold-way algorithm is the most effective. Finally, we present evidence that the asymptotic limits of the ground state energy for the isotropic case and for an anisotropic case of the 3D spin-glass model are very close and may even coincide.

  15. Bench-scale Kinetics Study of Mercury Reactions in FGD Liquors

    Energy Technology Data Exchange (ETDEWEB)

    Gary Blythe; John Currie; David DeBerry

    2008-03-31

    This document is the final report for Cooperative Agreement DE-FC26-04NT42314, 'Kinetics Study of Mercury Reactions in FGD Liquors'. The project was co-funded by the U.S. DOE National Energy Technology Laboratory and EPRI. The objective of the project has been to determine the mechanisms and kinetics of the aqueous reactions of mercury absorbed by wet flue gas desulfurization (FGD) systems, and develop a kinetics model to predict mercury reactions in wet FGD systems. The model may be used to determine optimum wet FGD design and operating conditions to maximize mercury capture in wet FGD systems. Initially, a series of bench-top, liquid-phase reactor tests were conducted and mercury species concentrations were measured by UV/visible light spectroscopy to determine reactant and byproduct concentrations over time. Other measurement methods, such as atomic absorption, were used to measure concentrations of vapor-phase elemental mercury, that cannot be measured by UV/visible light spectroscopy. Next, a series of bench-scale wet FGD simulation tests were conducted. Because of the significant effects of sulfite concentration on mercury re-emission rates, new methods were developed for operating and controlling the bench-scale FGD experiments. Approximately 140 bench-scale wet FGD tests were conducted and several unusual and pertinent effects of process chemistry on mercury re-emissions were identified and characterized. These data have been used to develop an empirically adjusted, theoretically based kinetics model to predict mercury species reactions in wet FGD systems. The model has been verified in tests conducted with the bench-scale wet FGD system, where both gas-phase and liquid-phase mercury concentrations were measured to determine if the model accurately predicts the tendency for mercury re-emissions. This report presents and discusses results from the initial laboratory kinetics measurements, the bench-scale wet FGD tests, and the kinetics modeling

  16. Quantum Chemical and Kinetic Study on Polychlorinated Naphthalene Formation from 3-Chlorophenol Precursor

    Directory of Open Access Journals (Sweden)

    Fei Xu

    2015-08-01

    Full Text Available Polychlorinated naphthalenes (PCNs are the smallest chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs and are often called dioxin-like compounds. Chlorophenols (CPs are important precursors of PCN formation. In this paper, mechanistic and kinetic studies on the homogeneous gas-phase formation mechanism of PCNs from 3-CP precursor were investigated theoretically by using the density functional theory (DFT method and canonical variational transition-state theory (CVT with small curvature tunneling contribution (SCT. The reaction priority of different PCN formation pathways were disscussed. The rate constants of crucial elementary steps were deduced over a wide temperature range of 600−1200 K. The mechanisms were compared with the experimental observation and our previous works on the PCN formation from 2-CP and 4-CP. This study shows that pathways ended with Cl elimination are favored over those ended with H elimination from the 3-CP precursor. The formation potential of MCN is larger than that of DCN. The chlorine substitution pattern of monochlorophenols has a significant effect on isomer patterns and formation potential of PCN products. The results can be input into the environmental PCN controlling and prediction models as detailed parameters, which can be used to confirm the formation routes of PCNs, reduce PCN emission and establish PCN controlling strategies.

  17. Adsorption of rutin with a novel β-cyclodextrin polymer adsorbent: thermodynamic and kinetic study.

    Science.gov (United States)

    Zhao, Jun; Lin, Dong-Qiang; Yao, Shan-Jing

    2012-11-06

    The adsorption properties toward rutin of a cyclodextrin polymer adsorbent CroCD-TuC 3 have been studied. The adsorption capacity is reduced as temperature and pH of solution rises, but increases with the increase of solvent polarity. Compared with Sephadex™ G-15 dextran gel beads, CroCD-TuC 3 shows dramatically higher isosteric enthalpy due to a significant contribution of rutin/β-cyclodextrin inclusion complex formation in CroCD-TuC 3 skeleton. A highlight in our study is that the pore diffusion model has been employed to describe the mass transfer inside the adsorbent pores. It reveals that the diffusion inside the pores is the rate-restricting step in the whole adsorption process. The effective pore diffusivity of rutin in CroCD-TuC 3 calculated is much lower than the diffusivity in diluted solution. The pore diffusion model is an available tool to investigate the profile of mass transfer inside the pores, and provides an effective method to describe adsorption kinetics. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Quantum Chemical and Kinetic Study on Polychlorinated Naphthalene Formation from 3-Chlorophenol Precursor.

    Science.gov (United States)

    Xu, Fei; Shi, Xiangli; Zhang, Qingzhu

    2015-08-31

    Polychlorinated naphthalenes (PCNs) are the smallest chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and are often called dioxin-like compounds. Chlorophenols (CPs) are important precursors of PCN formation. In this paper, mechanistic and kinetic studies on the homogeneous gas-phase formation mechanism of PCNs from 3-CP precursor were investigated theoretically by using the density functional theory (DFT) method and canonical variational transition-state theory (CVT) with small curvature tunneling contribution (SCT). The reaction priority of different PCN formation pathways were disscussed. The rate constants of crucial elementary steps were deduced over a wide temperature range of 600-1200 K. The mechanisms were compared with the experimental observation and our previous works on the PCN formation from 2-CP and 4-CP. This study shows that pathways ended with Cl elimination are favored over those ended with H elimination from the 3-CP precursor. The formation potential of MCN is larger than that of DCN. The chlorine substitution pattern of monochlorophenols has a significant effect on isomer patterns and formation potential of PCN products. The results can be input into the environmental PCN controlling and prediction models as detailed parameters, which can be used to confirm the formation routes of PCNs, reduce PCN emission and establish PCN controlling strategies.

  19. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies.

    Science.gov (United States)

    Tranter, Robert S; Giri, Binod R; Kiefer, John H

    2007-03-01

    A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr.

  20. Study of carbon dioxide gas treatment based on equations of kinetics in plasma discharge reactor

    Science.gov (United States)

    Abedi-Varaki, Mehdi

    2017-08-01

    Carbon dioxide (CO2) as the primary greenhouse gas, is the main pollutant that is warming earth. CO2 is widely emitted through the cars, planes, power plants and other human activities that involve the burning of fossil fuels (coal, natural gas and oil). Thus, there is a need to develop some method to reduce CO2 emission. To this end, this study investigates the behavior of CO2 in dielectric barrier discharge (DBD) plasma reactor. The behavior of different species and their reaction rates are studied using a zero-dimensional model based on equations of kinetics inside plasma reactor. The results show that the plasma reactor has an effective reduction on the CO2 density inside the reactor. As a result of reduction in the temporal variations of reaction rate, the speed of chemical reactions for CO2 decreases and very low concentration of CO2 molecules inside the plasma reactor is generated. The obtained results are compared with the existing experimental and simulation findings in the literature.

  1. Kinetic Study of Ce4+ Extraction with Cyanex 923

    Institute of Scientific and Technical Information of China (English)

    于桂红; 乐善堂; 李德谦; 凤优游

    2001-01-01

    Ce4+ extraction rate from aqueous sulphate solutions by Cyanex923 in heptane was studied using a constant interfacial cell with laminar flow at 30 ℃. The experimental hydrodynamic conditions were chosen and the contribution of diffusion to the measured rate of reaction was minimized. Cerium extraction rate was measured at different chemical composition by varying the concentrations of hydrogen ion, sulphate and Cyanex923. A cerium-Cyanex923(B) extractive is formed at the interface. The data were analyszed in terms of pseudo-first order constants and a reaction mechanism was developed.

  2. Study Of Hydration Kinetics and Rheological Behaviour of Guar Gum

    Directory of Open Access Journals (Sweden)

    K.Nandhini Venugopal

    2010-01-01

    Full Text Available Guar galactomannan is a plant polysaccharide with extensive pplications in food, paper, textile and petroleum industries. The main advantages for using guar are its low cost, easy availability and capacity to form viscous solutions and gels at low concentration. Additionally, chain architecture of guar galactomannan can be selectively modified to tailor properties of guar formulations and open up new opportunities for guar usage.The parameters such as hydration of guar, intrinsic viscosity measurements for determining the molecular weight of guar, rheological properties of guar were studied.

  3. An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

    2009-12-04

    Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents opposed-flow diffusion flame data for one large fatty acid methyl ester, methyl decanoate, and uses the experiments to validate an improved skeletal mechanism consisting of 648 species and 2998 reactions. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

  4. Kinetical study about the cobalt electrodeposition onto polycrystalline platinum

    Directory of Open Access Journals (Sweden)

    Clara Hilda Rios-Reyes

    2013-01-01

    Full Text Available An electrochemical study of Co electrodeposition onto polycrystalline Pt from an aqueous solution containing 10-2 M CoCl2 + 1 M NH4CI (pH = 9.3 was conducted at overpotential conditions. The current density transients showed two maxima that corresponded to two nucleation and growth processes. The entire transient behavior was adequately predicted considering the contribution to the total current of four different processes: a Langmuir-type adsorption process, a diffusion-controlled two-dimensional instantaneous nucleation, and two three-dimensional nucleation and growth processes.

  5. Comparative study, based on metamodels, of methods for controlling performance

    Directory of Open Access Journals (Sweden)

    Aitouche Samia

    2012-05-01

    Full Text Available The continuing evolution of technology and human behavior puts the company in an uncertain and evolving environment. The company must be responsive and even proactive; therefore, control performance becomes increasingly difficult. Choosing the best method of ensuring control by the management policy of the company and its strategy is also a decision problem. The aim of this paper is the comparative study of three methods: the Balanced Scorecard, GIMSI and SKANDIAs NAVIGATOR for choosing the best method for ensuring the orderly following the policy of the company while maintaining its durability. Our work is divided into three parts. We firstly proposed original structural and kinetic metamodels for the three methods that allow an overall view of a method. Secondly, based on the three metamodels, we have drawn a generic comparison to analyze completeness of the method. Thirdly, we performed a restrictive comparison based on a restrictive set of criteria related to the same aspect example organizational learning, which is one of the bricks of knowledge management for a reconciliation to a proactive organization in an environment disturbed and uncertain, and the urgent needs. We note that we applied the three methods are applied in our precedent works. [1][23

  6. Global aspects of photochemical air pollution: A kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, S.S. [Atmospheric Analysis and Consulting, Ventura, CA (United States); Fernandez, C.; Guyton, J.; Lee, C.P. [Arizona Department of Environmental Quality, Phoenix, AZ (United States)

    1994-12-31

    One of the most serious effects of increasing photochemical air pollution on a global basis is the production of high concentration of submicron aerosol in the atmosphere, resulting in unfavorable changes in weather patterns and world climate. The probability that these changes may occur with an unchecked increase in photochemical air pollution justifies a comprehensive control of pollutant emission as well as a detailed study into their atmospheric chemistry. Structure-reactivity relationships (SRR) and linear free energy relationships (LFER) are presented for environmentally important chemical reactions of unsaturated aliphatic contaminants in air and water. SRR of the form log k (k = rate constant for reaction with O{sub 3}, OH, and NO{sub 3}) vs ionization potential, and tortional frequency as well as LFER of the form log k (A) vs. log k (B) where A and B = O{sub 3}, OH, and NO{sub 3} are presented and can be used to estimate reaction rate constants and environmental persistence (in air and water) for many unsaturated compounds for which no data exist. As examples of application, rate constants for reactions of OH (gas phase), OH (water) and NO{sub 3} (gas phase) are estimated for many unsaturated compounds.

  7. Theoretical kinetic study of the low temperature oxidation of ethanol

    CERN Document Server

    Fournet, René; Bounaceur, Roda; Molière, Michel

    2009-01-01

    In order to improve the understanding of the low temperature combustion of ethanol, high-level ab initio calculations were performed for elementary reactions involving hydroxyethylperoxy radicals. These radicals come from the addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule. Unimolecular reactions involving hydroxyethylperoxy radicals and their radical products were studied at the CBS-QB3 level of theory. The results allowed to highlight the principal ways of decomposition of these radicals. Calculations of potential energy surfaces showed that the principal channels lead to the formation of HO2 radicals which can be considered, at low temperature, as slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of decomposition yields H atom and formic peracid, which is a branching agent that can strongly enhance the reactivity of ethanol in low temperature oxidation. In addition to these analyses, high-pressure limit rate constants were derived in the temperature rang...

  8. Dilute Acid Hydrolysis of Cowpea Hulls: A Kinetic Study

    Directory of Open Access Journals (Sweden)

    Chioma M. Onyelucheya

    2016-08-01

    Full Text Available In this study, dilute acid hydrolysis of cowpea hulls was carried out in two stages under the following conditions: pre-hydrolysis (4%v/v H2SO4, 121˚C, 30 minutes and hydrolysis ( at 10% and 15% v/v H2SO4,varied at different temperatures 150 oC, 160 oC, 170 oC and 180 oC for 2.5 hrs.. The substrate was characterized using both Fourier transform infrared spectroscopy and proximate analysis. The percentage lignocellulosic composition of the substrate was obtained for cellulose, hemicellulose and lignin as 34%, 14% and 4.7% respectively. Maximum glucose concentration of 8.09g was obtained using 10%v/v acid concentration at 170˚C after a reaction time of 90min. Saeman’s model gave a good fit for the experimental data. Activation energy for glucose formation using 10%v/v and 15%v/v H2SO4 was obtained as 38.28KJ and 82.204KJ respectively. From the results obtained it can be concluded that cowpea hulls can be converted to a useful product.

  9. A kinetic study on the lactoperoxidase catalyzed oxidation of estrogens.

    Science.gov (United States)

    Løvstad, Rolf A

    2006-12-01

    Lactoperoxidase, which is produced in mammary glands, is proposed to be involved in carcinogenesis, because of its ability to react with estrogenic molecules, oxidizing them to free radicals. In the present study the reactivity towards six species (estradiol, ethynylestradiol, estriol, estrone, pregnenolone and mestranol) was investigated by means of a NADH-coupled system. The enzyme activity towards estradiol, ethynylestradiol, estriol and estrone did not vary much, suggesting that the different substituents in the D-ring of the steroid had little effect on the reaction. A somewhat higher K (m)-value was obtained with estriol; possibly because of a more effective splitting of the enzyme-substrate complex into products. Pregnenolone, without resonance in the A-ring, and a methyl group in 19-position, did not react with the enzyme, in spite of having the proposed essential hydroxyl group in 3-position. Mestranol, with a methoxy group in 3-position, did not react with the enzyme either, supporting the suggestion that lactoperoxidase reacts with the 3-hydroxyl group of the estrogens.

  10. Interfacial Reactions in Confinement: Kinetics and Temperature Dependence of Reactions in Self-Assembled Monolayers Compared to Ultrathin Polymer Films

    NARCIS (Netherlands)

    Schönherr, Holger; Feng, C.L.; Shovsky, A.

    2003-01-01

    We report on a comparative study of the temperature dependence of the alkaline hydrolysis of N-hydroxy-succinimide (NHS) ester groups confined in self-assembled monolayers (SAMs) of 11,11'-dithiobis(N-hydroxysuccinimidylundecanoate) (NHS-C10) on gold and ultrathin films of poly(N-hydroxysuccinimidyl

  11. Kinetic and Thermodynamic Studies on the Phosphate Adsorption Removal by Dolomite Mineral

    Directory of Open Access Journals (Sweden)

    Xiaoli Yuan

    2015-01-01

    Full Text Available The efficiency of dolomite to remove phosphate from aqueous solutions was investigated. The experimental results showed that the removal of phosphate by dolomite was rapid (the removal rate over 95% in 60 min when the initial phosphate concentration is at the range of 10–50 mg/L. Several kinetic models including intraparticle diffusion model, pseudo-first-order model, Elovich model, and pseudo-second-order model were employed to evaluate the kinetics data of phosphate adsorption onto dolomite and pseudo-second-order model was recommended to describe the adsorption kinetics characteristics. Further analysis of the adsorption kinetics indicated that the phosphate removal process was mainly controlled by chemical bonding or chemisorption. Moreover, both Freundlich and Langmuir adsorption isotherms were used to evaluate the experimental data. The results indicated that Langmuir isotherm was more suitable to describe the adsorption characteristics of dolomite. Maximum adsorption capacity of phosphate by dolomite was found to be 4.76 mg phosphorous/g dolomite. Thermodynamic studies showed that phosphate adsorption was exothermic. The study implies that dolomite is an excellent low cost material for phosphate removal in wastewater treatment process.

  12. Biosorption of lead contaminated wastewater using cattails (Typha angustifolia leaves: kinetic studies

    Directory of Open Access Journals (Sweden)

    YEN LING SHARAIN-LIEW

    2011-07-01

    Full Text Available In this work, dried leaves of Typha angustifolia (TA, also known as the common cattail, were used as an adsorbent in kinetic studies of Pb(II adsorption from synthetic aqueous solutions. Batch adsorption studies with dried TA leaves were conducted and they were able to adsorb Pb(II from 100 mL of a 25 mg L-1 Pb(II solution effectively with the optimized dosage of 0.6 g. Adsorption equilibrium was achieved within 8 h with an effective removal of 86.04 %. Adsorption kinetics was further evaluated using four kinetic models, i.e., the pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich model. Fitting of the data was performed based on linear regression analysis. The sorption kinetic data fitted best to the pseudo-second order model with an R2 of 0.9979, followed closely by the Elovich model with an R2 of 0.9952. The obtained results showed the adsorption of Pb(II by TA leaves, which is an abundant biological material, is feasible, cheap and environmentally friendly.

  13. A kinetic study of copper(II) oxide powder reduction with hydrogen, based on thermogravimetry

    Energy Technology Data Exchange (ETDEWEB)

    Jelic, Dijana [Faculty of Medicine, Departmet of Pharmacy - Chair of Physical Chemistry, University of Banja Luka, Banja Luka, Bosnia and Herzegovina (Bosnia and Herzegowina); Tomic-Tucakovic, Biljana [Institute of General and Physical Chemistry, Studentski trg 12, 11158 Belgrade (Serbia); Mentus, Slavko, E-mail: slavko@ffh.bg.ac.rs [University of Belgrade, Faculty of Physical Chemistry, Studentski trg 12, 11185 Belgrade (Serbia)

    2011-07-10

    Highlights: {yields} The reduction of CuO by hydrogen was studied by thermogravimetry. {yields} The particle size of the samples varied inside the submicron range. {yields} The experimental data were fitted by means of a nucleation-growth model. {yields} The particle size influenced the kinetic parameters but not the reaction model. - Abstract: The reduction of powdery copper(II) oxide was carried out in a stream of gaseous mixture 25% H{sub 2} + Ar, and followed by thermogravimetry. The two samples of different history were studied: the commercial one, and that synthesized by citrate gel combustion method. The characterization of the starting materials, based on X-ray diffractometry and scanning electron microscopy, indicated equal crystal structure, but different particle size and morphology. The particle size and shape of the metallic particles obtained upon the reduction were observed by means of electron microscope. By a nonlinear regression analysis by means of a software Kinetics05, the experimental data were fitted with the nucleation-growth kinetic model, and the corresponding kinetic parameters were determined.

  14. Equilibrium, kinetic and thermodynamic studies of uranium biosorption by calcium alginate beads.

    Science.gov (United States)

    Bai, Jing; Fan, Fangli; Wu, Xiaolei; Tian, Wei; Zhao, Liang; Yin, Xiaojie; Fan, Fuyou; Li, Zhan; Tian, Longlong; Wang, Yang; Qin, Zhi; Guo, Junsheng

    2013-12-01

    Calcium alginate beads are potential biosorbent for radionuclides removal as they contain carboxyl groups. However, until now limited information is available concerning the uptake behavior of uranium by this polymer gel, especially when sorption equilibrium, kinetics and thermodynamics are concerned. In present work, batch experiments were carried out to study the equilibrium, kinetics and thermodynamics of uranium sorption by calcium alginate beads. The effects of initial solution pH, sorbent amount, initial uranium concentration and temperature on uranium sorption were also investigated. The determined optimal conditions were: initial solution pH of 3.0, added sorbent amount of 40 mg, and uranium sorption capacity increased with increasing initial uranium concentration and temperature. Equilibrium data obtained under different temperatures were fitted better with Langmuir model than Freundlich model, uranium sorption was dominated by a monolayer way. The kinetic data can be well depicted by the pseudo-second-order kinetic model. The activation energy derived from Arrhenius equation was 30.0 kJ/mol and the sorption process had a chemical nature. Thermodynamic constants such as ΔH(0), ΔS(0) and ΔG(0) were also evaluated, results of thermodynamic study showed that the sorption process was endothermic and spontaneous.

  15. A Comparative Study of Principals' Administrative Behaviour.

    Science.gov (United States)

    Chung, Kyung Ae

    1989-01-01

    Compared are the managerial behaviors and beliefs of Korean and American secondary school principals. Generalizations are proposed in the areas of work hours, work pace, communication skills, organizational style, instructional leadership, and other managerial behaviors. (16 references) (SI)

  16. Comparative study of environmental impact assessment methods ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-07-20

    Jul 20, 2009 ... Then both approaches required be comparing and contrasting. Among these methods .... should include political powers (factors related to the poli- cy test) and .... mental system and predict the component behavior. Using the ...

  17. Cure Kinetics of DGEBA with Hyperbranched Poly(3-hydroxyphenyl) Phosphate as Curing Agent Studied by Non-isothermal DSC

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cure kinetics of diglycidyl ether of bisphenol A(DGEBA) with hyperbranched poly(3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry(DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible -P-O- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Málek. It was found that the two-parameter autocatalytic model(esták-Berggren equation) is the most adequate one to describe the cure kinetics of the studied system at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.

  18. KINETIC STUDY OF CARBONYLATION OF METHANOL TO ACETIC ACID AND ACETIC ANHYDRIDE OVER A NOVEL COPOLYMER- BOUND CIS- DICARBONYLRHODIUM COMPLEX

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuying; YUAN Guoqing; CHEN Rongyao

    1989-01-01

    The kinetic study of carbonylation of methanol-acetic acid mixture to acetic acid and acetic anhydride over a cis-dicarbonylrhodium complex (MVM' Rh)coordinated with the ethylene diacrylate (M')crosslinked copolymer of methyl acrylate (M) and 2 - vinylpyridine (V) shows that the rate of reaction is zero order with respect to both reactants methanol and carbon monoxide, but first order in the concentrations of promoter methyl iodide and rhodium in the complex . Polar solvents can accelerate the reaction .Activation parameters were calculated from the experimental results, being comparable to that of the homogeneous system . A mechanism similar to that of soluble rhodium catalyst was proposed .

  19. A model based on equations of kinetics to study nitrogen dioxide behavior within a plasma discharge reactor.

    Science.gov (United States)

    Abedi-Varaki, Mehdi; Ganjovi, Alireza; Shojaei, Fahimeh; Hassani, Zahra

    2015-01-01

    In this work, a zero-dimensional kinetics model is used to study the temporal behavior of different species such as charged particles, radicals and excited states inside a Dielectric Barrier Discharge plasma reactor. It is shown that, the reactor significantly reduces the concentration of nitrogen monoxide as an environmental pollutant. After a drastic increase, a decrease in the concentration of the NO2 molecules inside the reactor is seen. Nitrogen monoxide molecules with a very low concentration are produced inside the reactor and its quick conversion to other products is proved. The obtained results are compared with the existing experimental and simulation findings, whenever possible.

  20. SKIN STAPLED OR SUTURED: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Veerendra Kumar

    2015-01-01

    Full Text Available BACKGROUND: The choice of wound closure after a surgical procedure has been a surgeon’s dilemma . The concerns have been as to how fast , uneventful , less painful , with minimal complications and comfortable will the patient’s recovery be. A well - known technology is surgical staples which are easier to use , less time consuming and a needle free method o f wound closure. OBJECTIVE: To compare skin staples with non - absorbable skin suture for skin closure in surgical laparotomy procedures for the following character : wound infection , dehiscence , cosmesis and postoperative pain . METHODS: This is a comparative study conducted on 100 patients divided in two groups randomly at Bapuji Hospital for cases undergoing surgical laparotomy procedures. Skin closure was done with 2 - 0 polyamide skin sutures in one group and skin closure was achieved with skin staples in th e other group. The outcome of wound was assessed on 3rd , 5th and 7th postoperative days using ASEPSIS score. Wound cosmesis was assessed on the 7th postoperative day and followed up at 1st month and 3rd month , using modified Hollander cosmesis scale. Postoperative pain was assessed using the visual analogue scale on the 1st , 3rd and 7th postoperative days. RESULTS : The mean wound ASPESIS scores on day 3 for skin staples and sutured group was 0.28 and 0.36 (p=0.7 respectively. The score on day 5 for staples and sutured group was 0.12 and 0.28 (p=0.4 respectively. The results in both the groups were the same , 0.08 on day 7(p=0. Wound cosmesis mean score assessment on day 7 for skin staples suturing group was 5.84 and 5.68 respectively (p=0.3. The mean score for cosmesis assessment at 1 month , and 3 rd month for skin staples and suturing group was 5.92 and 5.68 (p=0.1 and was 6.00 and 5.92 (p=0.36 respectively which was not satistically significant . The visual analogue scale score for postopera tive pain on 1st day , 3 rd and 7 th day for skin staples and suturing group 54

  1. Kinetic studies of elemental mercury adsorption in activated carbon fixed bed reactor.

    Science.gov (United States)

    Skodras, G; Diamantopoulou, Ir; Pantoleontos, G; Sakellaropoulos, G P

    2008-10-01

    Activated carbons are suitable materials for Hg(0) adsorption in fixed bed operation or in injection process. The fixed bed tests provide good indication of activated carbons effectiveness and service lives, which depend on the rates of Hg(0) adsorption. In order to correlate fixed bed properties and operation conditions, with their adsorptive capacity and saturation time, Hg(0) adsorption tests were realized in a bench-scale unit, consisted of F400 activated carbon fixed bed reactor. Hg(0) adsorption tests were conducted at 50 degrees C, under 0.1 and 0.35 ng/cm(3) Hg(0) initial concentrations and with carbon particle sizes ranging between 75-106 and 150-250 microm. Based on the experimental breakthrough data, kinetic studies were performed to investigate the mechanism of adsorption and the rate controlling steps. Kinetic models evaluated include the Fick's intraparticle diffusion equation, the pseudo-first order model, the pseudo-second order model and Elovich kinetic equation. The obtained experimental results revealed that the increase in particle size resulted in significant decrease of breakthrough time and mercury adsorptive capacity, due to the enhanced internal diffusion limitations and smaller external mass transfer coefficients. Additionally, higher initial mercury concentrations resulted in increased breakthrough time and mercury uptake. From the kinetic studies results it was observed that all the examined models describes efficiently Hg(0) breakthrough curves, from breakpoint up to equilibrium time. The most accurate prediction of the experimental data was achieved by second order model, indicating that the chemisorption rate seems to be the controlling step in the procedure. However, the successful attempt to describe mercury uptake with Fick's diffusion model and the first order kinetic model, reveals that the adsorption mechanism studied was complex and followed both surface adsorption and particle diffusion.

  2. Non-Isothermal Kinetics.

    Science.gov (United States)

    Brown, M. E.; Phillpotts, C. A. R.

    1978-01-01

    Discusses the principle of nonisothermal kinetics and some of the factors involved in such reactions, especially when considering the reliability of the kinetic parameters, compared to those of isothermal conditions. (GA)

  3. Kinetic and thermodynamic studies on the disulfide-bond reducing potential of hydrogen sulfide.

    Science.gov (United States)

    Vasas, Anita; Dóka, Éva; Fábián, István; Nagy, Péter

    2015-04-30

    The significance of persulfide species in hydrogen sulfide biology is increasingly recognized. However, the molecular mechanisms of their formation remain largely elusive. The obvious pathway of the reduction of biologically abundant disulfide moieties by sulfide was challenged on both thermodynamic and kinetic grounds. Using DTNB (5,5'-dithiobis-(2-nitrobenzoic acid), also known as Ellman's reagent) as a model disulfide we conducted a comprehensive kinetic study for its reaction with sulfide. The bimolecular reaction is relatively fast with a second-order rate constant of 889 ± 12 M(-1)s(-1) at pH = 7.4. pH dependence of the rate law revealed that the reaction proceeds via the bisulfide anion species with an initial nucleophilic thiol-disulfide exchange reaction to give 5-thio-2-nitrobenzoic acid (TNB) and TNB-persulfide with a pH independent second-order rate constant of 1090 ± 12 M(-1)s(-1). However, kinetic studies and stoichiometric analyses in a wide range of reactant ratios together with kinetic simulations revealed that it is a multistep process that proceeds via kinetically driven, practically irreversible reactions along the disulfide → persulfide → inorganic polysulfides axis. The kinetic model postulated here, which is fully consistent with the experimental data, suggests that the TNB-persulfide is further reduced by sulfide with a second-order rate constant in the range of 5 × 10(3) - 5 × 10(4) M(-1)s(-1) at pH 7.4 and eventually yields inorganic polysulfides and TNB. The reactions of cystine and GSSG with sulfide were found to be significantly slower and to occur via more complicated reaction schemes. (1)H NMR studies suggest that these reactions also generate Cys-persulfide and inorganic polysulfide species, but in contrast with DTNB, in consecutive equilibrium processes that are sensitive to changes in the reactant and product ratios. Collectively, our results demonstrate that the reaction of disulfides with sulfide is a highly system

  4. Electrochemical mechanism and kinetics studies of haloperidol and its assay in commercial formulations

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Francisco W.P. [Departamento de Quimica Analitica e Fisico-Quimica, Centro de Ciencias, Universidade Federal do Ceara, Bloco 940 Campus do Pici 60455-970, Fortaleza, CE (Brazil); Soares, Janete E.S. [Departamento de Farmacia, Faculdade de Farmacia, Odontologia e Enfermagem, Universidade Federal do Ceara, Rua Capitao Francisco Pedro, 1210 Rodolfo Teofilo 60430-370, Fortaleza, CE (Brazil); Becker, Helena; De Souza, Djenaine; Lima-Neto, Pedro de [Departamento de Quimica Analitica e Fisico-Quimica, Centro de Ciencias, Universidade Federal do Ceara, Bloco 940 Campus do Pici 60455-970, Fortaleza, CE (Brazil); Correia, Adriana N., E-mail: adriana@ufc.b [Departamento de Quimica Analitica e Fisico-Quimica, Centro de Ciencias, Universidade Federal do Ceara, Bloco 940 Campus do Pici 60455-970, Fortaleza, CE (Brazil)

    2011-02-01

    The kinetics and mechanism for electrochemical reduction of haloperidol, a psychotherapeutic drug used in the treatment of schizophrenia, were studied using square wave and cyclic voltammetries allied to a hanging mercury drop electrode. The experimental and voltammetric parameters were optimized at 0.04 mol L{sup -1} Brinton-Robinson buffer (pH 10), with a pulse potential frequency of 100 s{sup -1}, a pulse amplitude of 30 mV and scan increment of 2 mV. Two well-defined peaks were observed, which exhibited properties of fast electron transfer with a strong adsorption process of reactants and products on the electrode surface. The first peak was related to a fast and reversible anion-radical formation originating from the reduction of the carbonyl group, and the second was related to the irreversible reduction of the anion-radical previously formed. Analytical parameters such as: linearity range, equation of the analytical curves, correlation coefficients, detection and quantification limits, recovery efficiency, and relative standard deviation for intraday and interday were compared to similar results obtained by use of the UV-vis spectrophotometry technique, and the analytical results obtained in commercial formulations show that the voltammetric procedure using a hanging mercury drop electrode is suitable for analyzing haloperidol in complex commercial formulation samples.

  5. Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

    Science.gov (United States)

    Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

    2017-03-21

    Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (kobs) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO3(-) or Cl(-)) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO4(•)(-) or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal.

  6. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    Directory of Open Access Journals (Sweden)

    Patrik Storm

    Full Text Available Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1, which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  7. Refolding and enzyme kinetic studies on the ferrochelatase of the cyanobacterium Synechocystis sp. PCC 6803.

    Science.gov (United States)

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His(6)-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, k(cat), compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident.

  8. Equilibrium, kinetic and thermodynamic studies for adsorption of BTEX onto Ordered Mesoporous Carbon (OMC).

    Science.gov (United States)

    Konggidinata, Mas Iwan; Chao, Bing; Lian, Qiyu; Subramaniam, Ramalingam; Zappi, Mark; Gang, Daniel Dianchen

    2017-08-15

    Chemical and petrochemical industries produce substantial amounts of wastewater everyday. This wastewater contains organic pollutants such as benzene, toluene, ethylbenzene and xylenes (BTEX) that are toxic to human and aquatic life. Ordered Mesoporous Carbon (OMC), the adsorbent that possesses the characteristics of an ideal adsorbent was investigated to understand its properties and suitability for BTEX removal. Adsorption isotherms, adsorption kinetics, the effects of initial BTEX concentrations and temperatures on the adsorption process were studied. The OMCs were characterized using surface area and pore size analyzer, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). The results suggested that the Langmuir Isotherm and Pseudo-Second-Order Models described the experimental data well. The thermodynamic parameters, Gibbs free energy (ΔG°), the enthalpy change (ΔH°) and the entropy change (ΔS°) of adsorption indicated that the adsorption processes were physical, endothermic, and spontaneous. In addition, OMC had 27% higher overall adsorption capacities compared to granular activated carbon (GAC). Copyright © 2017 Elsevier B.V. All rights reserved.

  9. STUDY ON THE POLYMERIZATION KINETICS AND STABILITY OF P(UA)/MMA MICROEMULSION

    Institute of Scientific and Technical Information of China (English)

    Hong-tao Zhang; Tian-bin Ren; Zhao-hui Yin

    2001-01-01

    Urethane acrylate anionomer (APUA) as a kind of new type polymerizable emulsifier was synthesized using 2,4-toluene diisocyanate (TDI), polypropylene glycol (PPG), 2-hydroxyethyl methacrylate (HEMA) and dimethylolpropionic acid (DMPA). The critical micelle concentration (CMC) of APUA was measured by the methods of conductance and surface tension. The comparative studies between polymerizable emulsifier AUPA and conventional emulsifier sodium dodecyl sulfate (SDS) were carried out in the emulsion polymerization of methyl methacrylate (MMA). Polymerization kinetics,stability, size and morphology of the latex particles were investigated. It was found that in APUA both water soluble initiator potassium persulfate (KPS) and oil soluble initiator 2,2'-azobisisobutyronitrile (AIBN) can start the reaction of MMA, and the polymerization rate and yield were very high. On using AIBN as an initiator, the conversion-time behavior of MMA with APUA as emulsifier was different to that of SDS as emulsifier, signifying a different nucleation mechanism of the polymer latex particle. The average size of the two kinds of particles is about 50 nm. The particle size decreases with increasing emulsifier concentration. On using KPS as the initiator, APUA as emulsifier, cross-linking hydrogel of PMMA would be formed, but SDS was used as emulsifier and the hydrogel of PMMA was not present.

  10. Refolding and Enzyme Kinetic Studies on the Ferrochelatase of the Cyanobacterium Synechocystis sp. PCC 6803

    Science.gov (United States)

    Storm, Patrik; Tibiletti, Tania; Hall, Michael; Funk, Christiane

    2013-01-01

    Heme is a cofactor for proteins participating in many important cellular processes, including respiration, oxygen metabolism and oxygen binding. The key enzyme in the heme biosynthesis pathway is ferrochelatase (protohaem ferrolyase, EC 4.99.1.1), which catalyzes the insertion of ferrous iron into protoporphyrin IX. In higher plants, the ferrochelatase enzyme is localized not only in mitochondria, but also in chloroplasts. The plastidic type II ferrochelatase contains a C-terminal chlorophyll a/b (CAB) motif, a conserved hydrophobic stretch homologous to the CAB domain of plant light harvesting proteins and light-harvesting like proteins. This type II ferrochelatase, found in all photosynthetic organisms, is presumed to have evolved from the cyanobacterial ferrochelatase. Here we describe a detailed enzymological study on recombinant, refolded and functionally active type II ferrochelatase (FeCh) from the cyanobacterium Synechocystis sp. PCC 6803. A protocol was developed for the functional refolding and purification of the recombinant enzyme from inclusion bodies, without truncation products or soluble aggregates. The refolded FeCh is active in its monomeric form, however, addition of an N-terminal His6-tag has significant effects on its enzyme kinetics. Strikingly, removal of the C-terminal CAB-domain led to a greatly increased turnover number, kcat, compared to the full length protein. While pigments isolated from photosynthetic membranes decrease the activity of FeCh, direct pigment binding to the CAB domain of FeCh was not evident. PMID:23390541

  11. Kinetics and mechanistic study of competitive inhibition of thymidine phosphorylase by 5-fluoruracil derivatives.

    Science.gov (United States)

    Petaccia, Manuela; Gentili, Patrizia; Bešker, Neva; D'Abramo, Marco; Giansanti, Luisa; Leonelli, Francesca; La Bella, Angela; Gradella Villalva, Denise; Mancini, Giovanna

    2016-04-01

    In a previous investigation, cationic liposomes formulated with new 5-FU derivatives, differing for the length of the polyoxyethylenic spacer that links the N(3) position of 5-FU to an alkyl chain of 12 carbon atoms, showed a higher cytotoxicity compared to free 5-FU, the cytotoxic effect being directly related to the length of the spacer. To better understand the correlation of the spacer length with toxicity, we carried out initial rate studies to determine inhibition, equilibrium and kinetic constants (KI, KM, kcat), and get inside inhibition activity of the 5-FU derivatives and their mechanism of action, a crucial information to design structural variations for improving the anticancer activity. The experimental investigation was supported by docking simulations based on the X-ray structure of thymidine phosphorylase (TP) from Escherichia coli complexed with 3'-azido-2'-fluoro-dideoxyuridin. Theoretical and experimental results showed that all the derivatives exert the same inhibition activity of 5-FU either as monomer and when embedded in lipid bilayer.

  12. Laboratory evaluation of the pivot-shift phenomenon with use of kinetic analysis: a preliminary study.

    Science.gov (United States)

    Sanchis-Alfonso, Vicente; Baydal-Bertomeu, José-María; Castelli, Andrea; Montesinos-Berry, Erik; Marín-Roca, Susana; Garrido-Jaén, José-David

    2011-07-06

    Currently, a suitable and reliable noninvasive method to evaluate rotational stability in vivo in anterior cruciate ligament-deficient knees, particularly during sports movements, does not exist. We speculated that if there is a rotational instability, the patient would avoid reaching a high pivoting moment during pivoting activities as a defense mechanism, and that the ground reaction moment, as registered by dynamometric platforms, would be reduced. On the basis of this hypothesis, we developed a study using kinetic analysis to evaluate rotational stability under dynamic loading. Thirty recreationally active athletes, including fifteen healthy subjects and fifteen with an anterior cruciate ligament-deficient knee, were recruited for this study. Patients performed jumping with pivoting with internal tibial rotation and external tibial rotation on the dynamometric platform with both the healthy and the injured limb. The quantitative results were graphically plotted, and the following parameters were evaluated: loading moment, pivoting moment, torque amplitude, loading slope, pivoting slope, percentage of pivoting with load, loading impulse, pivoting impulse, and maximum body rotation angle. There were no significant differences between the dominant and nondominant knees in the control group during the jumping with pivoting and external tibial rotation test with regard to the pivoting moment (p = 0.805), pivoting slope (p = 0.716), pivoting impulse 2 (p = 0.858), and pivoting impulse 3 (p = 0.873). In patients with a chronic tear of the anterior cruciate ligament, there was a significant decrease of the pivoting moment (p = 0.02), pivoting slope (p = 0.005), pivoting impulse 2 (p = 0.006), and pivoting impulse 3 (p = 0.035) during the jumping with pivoting and external tibial rotation test in the anterior cruciate ligament-deficient knee compared with the healthy, contralateral knee. Kinetic analysis with use of a dynamic platform can objectively detect alterations

  13. Studies of Dye Sensitisation Kinetics and Sorption Isotherms of Direct Red 23 on Titania

    Directory of Open Access Journals (Sweden)

    Peter J. Holliman

    2008-01-01

    Full Text Available Sorption kinetics and isotherms have been measured for a commercial dye (Direct Red 23 on different samples of powdered Titania, and the data were analysed to better understand the dye sensitization process for dye sensitised solar cells (DSSCs. For the sorption kinetics, the data show rapid initial sorption (<1 hour followed by slower rate of increasing uptake between 1 and 24 hours. While higher initial concentrations of dye correspond to higher sorption overall, less dye is absorbed from higher initial dye concentrations when considered as percentage uptake. The correlation between the sorption data and model isotherms has been considered with time. The Langmuir model shows better correlations compared to the Freundlich isotherm. The dye uptake data has also been correlated with Titania characterization data (X-ray diffraction, scanning electron microscopy, BET and zero point charge analysis. Kinetic data show significantly better fits to second-order models compared to first order. This suggests that chemisorption is taking place and that the interaction between the dye sorbate and the Titania sorbent involves electron sharing to form an ester bond.

  14. Prediction of vapour-liquid equilibria for the kinetic study of processes based on synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Di Serio, M.; Tesser, R.; Cozzolino, M.; Santacesaria, E. [Naples Univ., Napoli (Italy). Dept. of Chemistry

    2006-07-01

    Syngas is normally used in the production of a broad range of chemicals and fuels. In many of these processes multiphase reactors, gas-liquid or gas-liquid-solid are used. Kinetic studies in multiphase systems are often complicated by the non-ideal behaviour of reagents and/or products that are consistently partitioned between the liquid and the vapour phase. Moreover, as often kinetic data are collected in batch conditions for the liquid phase, activity coefficients of the partitioned components can consistently change during the time as a consequence of changing the composition of the reaction mixture. Therefore, it is necessary, in these cases, to known the vapor-liquid equilibria (VLE) in order to collect and to interpret correctly the kinetic data. The description of phase equilibria, at high pressures, is usually performed by means of an EOS (Equation of State) allowing the calculation of fugacity coefficients, for each component, in both phases and determining the partition coefficients but the EOS approach involves the experimental determination of the interaction parameters for all the possible binary system of the mixture. For multicomponent mixtures a complete experimental determination of vapourliquid equilibria is very hard, also considering the high pressure and temperatures used. Some predictive group contribution methods have been recently developed. In this paper, we will describe in detail the application of these methods to the methanol homologation, as an example, with the scope of determining more reliable kinetic parameters for this reaction. (orig.)

  15. Kinetic Study of Hydroxyl and Sulfate Radical-Mediated Oxidation of Pharmaceuticals in Wastewater Effluents.

    Science.gov (United States)

    Lian, Lushi; Yao, Bo; Hou, Shaodong; Fang, Jingyun; Yan, Shuwen; Song, Weihua

    2017-02-13

    Advanced oxidation processes (AOPs), such as hydroxyl radical (HO(•))- and sulfate radical (SO4(•-))-mediated oxidation, are alternatives for the attenuation of pharmaceuticals and personal care products (PPCPs) in wastewater effluents. However, the kinetics of these reactions needs to be investigated. In this study, kinetic models for 15 PPCPs were built to predict the degradation of PPCPs in both HO(•)- and SO4(•-)-mediated oxidation. In the UV/H2O2 process, a simplified kinetic model involving only steady state concentrations of HO(•) and its biomolecular reaction rate constants is suitable for predicting the removal of PPCPs, indicating the dominant role of HO(•) in the removal of PPCPs. In the UV/K2S2O8 process, the calculated steady state concentrations of CO3(•-) and bromine radicals (Br(•), Br2(•-) and BrCl(•-)) were 600-fold and 1-2 orders of magnitude higher than the concentrations of SO4(•-), respectively. The kinetic model, involving both SO4(•-) and CO3(•-) as reactive species, was more accurate for predicting the removal of the 9 PPCPs, except for salbutamol and nitroimidazoles. The steric and ionic effects of organic matter toward SO4(•-) could lead to overestimations of the removal efficiencies of the SO4(•-)-mediated oxidation of nitroimidazoles in wastewater effluents.

  16. A study on degradation kinetics of ascorbic acid in amla (Phyllanthus emblica L.) during cooking.

    Science.gov (United States)

    Nisha, P; Singhal, Rekha S; Pandit, Aniruddha B

    2004-08-01

    The kinetics of ascorbic acid degradation in amla (Phyllanthus emblica L.) as well as in pure ascorbic acid solutions at initial concentrations present in amla over a temperature range of 50-120 degrees C (steady-state temperature) has been studied. The ascorbic acid degradation followed first-order reaction kinetics where the rate constant increased with an increase in temperature. The temperature dependence of degradation was adequately modeled by the Arrhenius equation. The activation energies were found to be 4.09 kcal/mole for amla and 4.49 kcal/mole for pure vitamin solution. The degradation kinetics of ascorbic acid was also evaluated in normal open pan cooking, pressure-cooking and a newly developed and patented fuel-efficient EcoCooker (unsteady state heating process). A mathematical model was developed using the steady-state kinetic parameters obtained to predict the losses of ascorbic acid from the time-temperature data of the unsteady state heating processing method. The results obtained indicate the ascorbic acid degradation is of a similar order of magnitude in all the methods of cooking.

  17. Biosorption study of Ni2+ and Cr3+ by Sargassum filipendula: kinetics and equilibrium

    Directory of Open Access Journals (Sweden)

    A. A. Seolatto

    2014-03-01

    Full Text Available In this work, the biosorption of Cr3+ and Ni2+ by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for mono- and multi-component solutions in a batch reactor at pH 3.0 and 30 ºC. The results from the kinetic experiments showed that Cr3+ adsorbs slower than Ni2+. This behavior was explained by means of a mechanistic analysis, which showed that Cr3+ uptake presented three adsorption stages, whereas Ni2+ adsorption presents only two. The mono-component equilibrium data, along with binary kinetic data obtained from mono-component experiments, showed that, although the kinetics for Cr3+ removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni2+ is desorbed from the biomass as Cr3+ adsorbs. The binary equilibrium data also presented this behavior. The binary data was also modeled by using modified forms of the Langmuir, Jain and Snoeyink, and Langmuir-Freundlich isotherms. However, the prediction obtained presented low accuracy. An alternative modeling with artificial neural networks was presented and the results showed that this technique could be a promising tool to represent binary equilibrium data. The main contribution of this work was to obtain experimental data for Cr3+/Ni2+ adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.

  18. In-situ study of hydriding kinetics in Pd-based thin film systems

    Energy Technology Data Exchange (ETDEWEB)

    Delmelle, Renaud; Proost, Joris [Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium). Div. of Materials and Process Engineering

    2010-07-01

    The hydriding kinetics of Pd thin films has been investigated in detail. The key experimental technique used in this work consists of a high resolution curvature measurement setup, which continuously monitors the reflections of multiple laser beams coming off a cantilevered sample. After mounting the sample inside a vacuum chamber, a H-containing gas mixture is introduced to instantaneously generate a given hydrogen partial pressure (p{sub H2}) inside the chamber. The resulting interaction of H with the Pd layer then leads to a volume expansion of the thin film system. This induces in turn changes in the sample curvature as a result of internal stresses developing in the Pd film during a hydriding cycle. Based on such curvature date obtained in-situ at different p{sub H2}, a two-step model for the kinetics of Pd-hydride formation has been proposed and expressions for the hydrogen adsorption and absorption velocities have been derived. The rate-limiting steps have been identified by studying the p{sub H2}-dependence of these velocities. Furthermore, from our in-situ experimental data, relevant kinetic parameters have been calculated. The effect of dry air exposure of the Pd films on the hydriding kinetics has been considered as well. (orig.)

  19. A simple model for complex dissolution kinetics: a case study of norfloxacin.

    Science.gov (United States)

    Skrdla, Peter J

    2007-10-18

    A new semi-empirical model, particularly useful for studying complex dissolution kinetics, is presented here. It uses only two 'fit parameters', each possessing physically relevant units (in the time domain). The model is based on the idea that dispersion (variation) in the activation energy barrier may arise in certain cases, as a result of (quantized) molecular kinetic energies affecting the speed of the rate-determining step (r.d.s.) of the dissolution event. For such 'dispersive dissolutions', the r.d.s. is assumed to involve 2D denucleation. The author's dispersive kinetic model is shown to be applicable to the dissolution of various formulations of norfloxacin which produce very asymmetric, sigmoidal concentration versus time (C-t) profiles. It is derived by assuming an activation energy distribution having the functional form of the Maxwell-Boltzmann (M-B) distribution, coupled with a first-order rate expression. However, this model can also be reduced to give the same functional form as the classical Noyes-Whitney equation, in order to accurately fit/describe dissolution profiles which appear logarithmic (such profiles are due to dissolution phenomena that are not dispersive; i.e. for cases where the activation energy is essentially single-valued). Thus, the kinetic model presented in this work may potentially find broad applicability to the modeling of various dissolution trends observed in the literature.

  20. Kinetic study of austenite formation during continuous heating of unalloyed ductile iron

    Institute of Scientific and Technical Information of China (English)

    Octavio Vzquez-Gmez; Jos Antonio Barrera-Godnez; Hctor Javier Vergara-Hernndez

    2015-01-01

    The austenite formation kinetics in unalloyed cast ductile iron was studied on the basis of dilatometry measurements, and Avrami’s equation was used to estimate the material’s kinetic parameters. A continuous heating transformation diagram was constructed us-ing heating rates in the range of 0.06 to 0.83°C⋅s−1. As the heating rate was augmented, the critical temperatures, c1A and Aα, as well as the intercritical range, which was evaluated as the difference between the critical temperatures, α c1Δ T =A −A , increased. At a low heating rate, the kinetics of austenite formation was slow as a consequence of the iron’s silicon content. The effect of heating rate on k and n, the kinetic parameters of Avrami’s equation, was also determined. Parameter n, which is associated with nucleation sites and growth geometry, de-creased with an increase in heating rate. In addition, parameter k increased with the increase of heating rate, suggesting that the nucleation and growth rates are carbon-and silicon-diffusion controlled during austenite formation under continuous heating.

  1. Mechanistic and kinetic studies of high-temperature coal gas desulfurization sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Lew, S.; Flytzani-Stephanopoulos, M.; Sarofim, A.F.

    1991-10-01

    The overall objective of this project was to investigate the properties of and evaluate mixed oxides of zinc and titanium for hot fuel gas desulfurization. Uncombined ZnO was also investigated as a base case. Detailed investigation of the reduction and sulfidation reactions of Zn-Ti-O sorbents was performed. The intrinsic kinetics and the product layer diffusion rates in reduction and sulfidation were determined. Kinetic experiments with sorbents containing various Zn/Ti atomic ratios were performed. Chemical phase and structural transformations were followed by various methods. The results were compared to similar experiments performed with ZnO. The purpose of these experiments was to determine how the presence of titanium dioxide affects the reduction and sulfidation of ZnO. This information would be used to identify and select the sorbent composition that gives the best combination of low reduction rate and acceptable sulfidation performance at temperatures exceeding 600{degree}C. (VC)

  2. Study of Enzymatic Hydrolysis of Fructans from Agave salmiana Characterization and Kinetic Assessment

    Directory of Open Access Journals (Sweden)

    Christian Michel-Cuello

    2012-01-01

    Full Text Available Fructans were extracted from Agave salmiana juice, characterized and subjected to hydrolysis process using a commercial inulinase preparation acting freely. To compare the performance of the enzymatic preparation, a batch of experiments were also conducted with chicory inulin (reference. Hydrolysis was performed for 6 h at two temperatures (50, 60∘C and two substrate concentrations (40, 60 mg/ml. Hydrolysis process was monitored by measuring the sugars released and residual substrate by HPLC. A mathematical model which describes the kinetics of substrate degradation as well as fructose production was proposed to analyze the hydrolysis assessment. It was found that kinetics were significantly influenced by temperature, substrate concentration, and type of substrate (P<0.01. The extent of substrate hydrolysis varied from 82 to 99%. Hydrolysis product was mainly constituted of fructose, obtaining from 77 to 96.4% of total reducing sugars.

  3. Study of enzymatic hydrolysis of fructans from Agave salmiana characterization and kinetic assessment.

    Science.gov (United States)

    Michel-Cuello, Christian; Ortiz-Cerda, Imelda; Moreno-Vilet, Lorena; Grajales-Lagunes, Alicia; Moscosa-Santillán, Mario; Bonnin, Johanne; González-Chávez, Marco Martín; Ruiz-Cabrera, Miguel

    2012-01-01

    Fructans were extracted from Agave salmiana juice, characterized and subjected to hydrolysis process using a commercial inulinase preparation acting freely. To compare the performance of the enzymatic preparation, a batch of experiments were also conducted with chicory inulin (reference). Hydrolysis was performed for 6 h at two temperatures (50, 60 °C) and two substrate concentrations (40, 60 mg/ml). Hydrolysis process was monitored by measuring the sugars released and residual substrate by HPLC. A mathematical model which describes the kinetics of substrate degradation as well as fructose production was proposed to analyze the hydrolysis assessment. It was found that kinetics were significantly influenced by temperature, substrate concentration, and type of substrate (P < 0.01). The extent of substrate hydrolysis varied from 82 to 99%. Hydrolysis product was mainly constituted of fructose, obtaining from 77 to 96.4% of total reducing sugars.

  4. Kinetic studies of the infrared-induced reaction between atomic chlorine and solid parahydrogen

    Science.gov (United States)

    Raston, Paul L.; Kettwich, Sharon C.; Anderson, David T.

    2015-04-01

    We present Fourier-transform infrared (FTIR) spectroscopic studies of the IR-induced Cl + H2(v = 1) → HCl + H reaction in a parahydrogen (pH2) matrix aimed at distinguishing between two proposed reactions mechanisms; direct-IR and vibron-mediated. The Cl atom reactants are produced via 355 nm in situ photolysis of a Cl2 doped pH2 matrix. After photolysis is complete, a long-pass IR filter in the FTIR beam is removed and we measure the ensuing IR-induced reaction kinetics using rapid scan FTIR spectroscopy. We follow both the decay of the Cl atom reactant and growth of the HCl product using the Cl spin-orbit (SO) + Q1(0) and HCl R1(0) transitions, respectively. We show the IR-induced reaction mechanism depends on the spectral profile of the IR radiation; for IR spectral profiles that have significant IR intensities between 4000 and 5000 cm-1 we observe first-order kinetics that are assigned to a vibron-mediated mechanism and for spectral profiles that have significant IR intensities that include the Cl SO + Q1(0) transition near 5094 cm-1 we observe bi-exponential kinetics that are dominated by the direct-IR mechanism at early reaction times. We can distinguish between the two mechanisms using the observed kinetics. We investigate the reaction kinetics for different FTIR optical setups, for a range of sample conditions, and start and stop the IR-induced reaction to investigate the importance of secondary H atom reactions. We also study the IR-induced reaction in Br/Cl co-doped pH2 samples and show the presence of the Br atom quenches the vibron-mediated reaction kinetics presumably because the Br-atoms serve as efficient vibron traps. This paper indicates that in a highly enriched pH2 matrix the H atoms that are produced by the IR-induced Cl atom reaction likely do not play a significant role in the measured reaction kinetics which implies these secondary H atom reactions are highly selective.

  5. Temperature dependence of protein solubility-determination, application to crystallization, and growth kinetics studies

    Science.gov (United States)

    Rosenberger, Franz

    1993-01-01

    A scintillation method was developed for determinations of the temperature dependence of the solubility, and of nucleation induction times of proteins, in 50-100 mu(l) volumes of solution. Solubility data for lysozyme and horse serum albumin were obtained for various combinations of pH and precipitant concentrations. These data and the nucleation induction information were used for dynamic crystallization control, that is, for the controlled separation of nucleation and growth stages. Individual lysozyme and horse serum albumin crystals were grown in 15-20 mu(l) solution volumes contained in x-ray capillaries. The morphology and kinetics of the growth and dissolution of lysozyme in aqueous solutions with 2.5 percent NaCl and at pH = 4.5 was studied in situ with a depth resolution of 300 A (4 unit cells) by high resolution optical microscopy and digital image processing. The bulk super- or under saturation, sigma, of the solution inside a closed growth cell was controlled by temperature. The growth habit was bound by (110) and (101) faces that grew through layer spreading, although with different growth rate dependencies on supersaturation/temperature. At sigma less than 10 (obtained at higher temperatures) growth was purely kinetic ally controlled, with impurity effects (macrostep formation and kinetic hindrance) becoming significant for sigma less than 2. At sigma greater than 10 (lower temperatures), anisotropies in the interfacial kinetics were more pronounced, with interfacial kinetics and bulk transport becoming equally important to the growth morphology. Growth rates were growth history dependent. The formation of striations (layers of irregularly incorporated solution) was unambiguously correlated with growth temperature variations. Etching exposed dislocations and various high-index faces whose growth morphologies were studied during return to the steady state growth form. Growth steps were observed to originate from two-dimensional nuclei or from outcrops

  6. Chemical kinetic study of the effect of a biofuel additive on jet-A1 combustion.

    Science.gov (United States)

    Dagaut, Philippe; Gaïl, Sandro

    2007-05-17

    The kinetics of oxidation of kerosene Jet A-1 and a kerosene/rapeseed oil methyl ester (RME) mixture (80/20, mol/mol) (biokerosene) was studied experimentally in a jet-stirred reactor at 10 atm and constant residence time, over the temperature range 740-1200 K, and for variable equivalence ratios (0.5-1.5). Concentration profiles of the reactants, stable intermediates, and final products were obtained by probe sampling followed by on-line and off-line gas chromatography analyses. The oxidation of these fuels in these conditions was modeled using a detailed kinetic reaction mechanism consisting of 2027 reversible reactions and 263 species. The surrogate biokerosene model fuel used here consisted of a mixture of n-hexadecane, n-propylcyclohexane, n-propylbenzene, and n-decane, where the long-chain methyl ester fraction was simply represented by n-hexadecane. The proposed kinetic reaction mechanism used in the modeling yielded a good representation of the kinetics of oxidation of kerosene and biokerosene under jet-stirred reactor conditions and of kerosene in a premixed flame. The data and the model showed the biokerosene (Jet A-1/RME mixture) has a slightly higher reactivity than Jet A-1, whereas no major modification of the product distribution was observed besides the formation of small unsaturated methyl esters produced from RME's oxidation. The model predicts no difference in the ignition delays of kerosene and biokerosene. Using the proposed kinetic scheme, the formation of potential soot precursors was studied with particular attention.

  7. Kinetic Defects Induced by Melittin in Model Lipid Membranes: A Solution Atomic Force Microscopy Study.

    Science.gov (United States)

    Pan, Jianjun; Khadka, Nawal K

    2016-05-26

    Quantitative characterization of membrane defects (pores) is important for elucidating the molecular basis of many membrane-active peptides. We study kinetic defects induced by melittin in vesicular and planar lipid bilayers. Fluorescence spectroscopy measurements indicate that melittin induces time-dependent calcein leakage. Solution atomic force microscopy (AFM) is used to visualize melittin-induced membrane defects. After initial equilibration, the most probable defect radius is ∼3.8 nm in 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) bilayers. Unexpectedly, defects become larger with longer incubation, accompanied by substantial shape transformation. The initial defect radius is ∼4.7 nm in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Addition of 30 mol % cholesterol to DOPC bilayers suppresses defect kinetics, although the inhibitory impact is negated by longer incubation. Overall, the kinetic rate of defect development follows DLPC > DOPC > DOPC/cholesterol. Kinetic defects are also observed when anionic lipids are present. Based on the observation that defects can occupy as large as 40% of the bilayer surface, we propose a kinetic defect growth model. We also study the effect of melittin on the phase behavior of DOPC/egg-sphingomyelin/cholesterol bilayers. We find that melittin initially suppresses or eliminates liquid-ordered (Lo) domains; Lo domains gradually emerge and become the dominant species with longer incubation; and defects in phase-coexisting bilayers have a most probable radius of ∼5 nm and are exclusively localized in the liquid-disordered (Ld) phase. Our experimental data highlight that melittin-induced membrane defects are not static; conversely, spontaneous defect growth is intrinsically associated with membrane permeabilization exerted by melittin.

  8. The Teaching of Anthropology: A Comparative Study.

    Science.gov (United States)

    Lombard, Jacques

    1984-01-01

    College-level anthropology teaching in various countries, including Belgium, France, Germany, the Netherlands, Portugal, South Africa, the United Kingdom, and Yugoslavia, is compared. Terminology is examined and historical background is provided. Also discussed are educational crises, the organization of teaching, and teaching methods. (RM)

  9. Kinetics study of oil extraction from Citrus auranticum L. by solvent-free microwave extraction

    OpenAIRE

    Heri Septya Kusuma; Prilia Dwi Amelia; Cininta Admiralia; Mahfud Mahfud

    2016-01-01

    Citrus and its oil are of high economic and medicinal value because of their multiple uses, such as in the food industry, cosmetics and folk medicine. The aim of this study is to investigate the potential of solvent-free microwave extraction for the extraction of essential oils from Citrus auranticum L. peels. Specifically, this study verifies the kinetics based on second-order model and mechanism of solvent-free microwave extraction of Citrus auranticum L. peels. Solvent-free microwave extra...

  10. Kinetic, Thermodynamic and Structural Studies of Native and N-Bromosuccinimide-Modified Mushroom Tyrosinase

    Directory of Open Access Journals (Sweden)

    Saeed Emami

    2016-10-01

    Full Text Available Background Mushroom tyrosinase (MT as a metalloenzyme is a good model for mechanistic studies of melanogenesis. To recognize the mechanism of MT action, it is important to investigate its inhibition, activation, mutation, and modification properties. Objectives In this study, the chemical modification of MT tryptophan residues was carried out by using N-bromosuccinimide (NBS and then, the activity, stability, and structure of the native and modified enzymes were compared. Methods Chemical modification of MT tryptophan residues was accomplished by enzyme incubation with different concentrations of NBS. The relative activity of native and modified MT was investigated through catecholase enzyme reaction in presence of dihydroxyphenylalanine (L-Dopa as substrate. Thermodynamic parameters including standard Gibbs free energy change (∆G25°C and Melting temperature (Tm were obtained from thermal denaturation of the native and modified enzymes. The circular dichroism and intrinsic fluorescence techniques were used to study secondary and tertiary structure of MT, respectively. All experiments were conducted in 2015 in biophysical laboratory of Qazvin University of Medical Sciences and Islamic Azad University, Science and Research Branch, Tehran. Results The relative activity reduced from 100% for native enzyme to 10%, 7.9%, and 6.4% for modified MT with different NBS of concentrations 2, 10, and 20 mM, respectively. Thermal instability of modified enzyme was confirmed by decreased Tm and ∆G25°C values after modification. In accordance with kinetic and thermodynamic results, the lower stability of modified MT was observed from the changes occurred on its secondary and tertiary structures. Conclusions Chemical modification of tryptophan residues with NBS reduces the activity and stability of MT simultaneously with its structural change. Thus, this study emphasizes the crucial role of tryptophan residues in the structure-function relationship of MT

  11. A Rapid Compression Expansion Machine (RCEM) for studying chemical kinetics: Experimental principle and first applications

    CERN Document Server

    Werler, Marc; Maas, Ulrich

    2016-01-01

    A novel extension of a rapid compression machine (RCM), namely a Rapid Compression Expansion Machine (RCEM), is described and its use for studying chemical kinetics is demonstrated. Like conventional RCMs, the RCEM quickly compresses a fuel/air mixture by pushing a piston into a cylinder; the resulting high temperatures and pressures initiate chemical reactions. In addition, the machine can rapidly expand the compressed gas in a controlled way by pulling the piston outwards again. This freezes chemical activity after a pre-defined reaction duration, and therefore allows a convenient probe sampling and ex-situ gas analysis of stable species. The RCEM therefore is a promising instrument for studying chemical kinetics, including also partially reacted fuel/air mixtures. The setup of the RCEM, its experimental characteristics and its use for studying chemical reactions are outlined in detail. To allow comparisons of RCEM results with predictions of chemical reaction mechanisms, a simple numerical model of the RCE...

  12. Ochratoxin A kinetics: a review of analytical methods and studies in rat model.

    Science.gov (United States)

    Vettorazzi, A; González-Peñas, E; de Cerain, A López

    2014-10-01

    Ochratoxin A (OTA) is a thermostable mycotoxin that contaminates a great variety of foodstuffs. It is nephrotoxic in all of the mammalian species tested, the pig being the most sensitive one; among rodents, rats are the most susceptible to OTA carcinogenicity. Kinetics, by studying the absorption, distribution, metabolism and excretion of xenobiotics, is an important tool in the extrapolation of animal toxicity data for human risk assessment. The most important kinetic studies performed with OTA in rats are reviewed, together with the different methods used for OTA quantification in biological matrices. Twelve studies in Wistar, Sprague-Dawley or F344 rats, using radiolabeled OTA or TLC, HPLC-FLD or LC/MS have been summarized. Very often methods validated for food have been directly applied to tissues. Strain, sex and age differences have been detected but the interpretation is difficult due to the different experimental conditions, and the connection of the several factors that may account for these differences.

  13. Kinetic, isotherm and thermodynamic studies of amaranth dye biosorption from aqueous solution onto water hyacinth leaves.

    Science.gov (United States)

    Guerrero-Coronilla, Imelda; Morales-Barrera, Liliana; Cristiani-Urbina, Eliseo

    2015-04-01

    The present study explored the kinetics, equilibrium and thermodynamics of amaranth (acid red 27) anionic dye (AD) biosorption to water hyacinth leaves (LEC). The effect of LEC particle size, contact time, solution pH, initial AD concentration and temperature on AD biosorption was studied in batch experiments. AD biosorption increased with rising contact time and initial AD concentration, and with decreasing LEC particle size and solution pH. Pseudo-second-order chemical reaction kinetics provided the best correlation for the experimental data. Isotherm studies showed that the biosorption of AD onto LEC closely follows the Langmuir isotherm, with a maximum biosorption capacity of about 70 mg g(-1). The thermodynamic parameters confirm that AD biosorption by LEC is non-spontaneous and endothermic in nature. Results indicate that LEC is a strong biosorbent capable of effective detoxification of AD-laden wastewaters.

  14. Catatonic schizophrenia: an international comparative study.

    Science.gov (United States)

    Chandrasena, R

    1986-04-01

    Thirty-five hospitalized catatonic schizophrenic patients from Sri Lanka were compared with 22 patients in the U.K. and 13 in Canada. The phenomenology was established using the Present State Examination. Results suggest that ethnicity, chronicity of illness and reception of neuroleptic treatment may influence the lower prevalence of catatonic symptoms among the U.K. and Canadian schizophrenics. Onset of illness appears to be among young adults and mutism, stupor, mannerisms, stereotypes and negativism were the common catatonic symptoms observed.

  15. Thermodynamic and kinetic study of phenol degradation by a non-catalytic wet air oxidation process.

    Science.gov (United States)

    Lefèvre, Sébastien; Boutin, Olivier; Ferrasse, Jean-Henry; Malleret, Laure; Faucherand, Rémy; Viand, Alain

    2011-08-01

    This work is dedicated to an accurate evaluation of thermodynamic and kinetics aspects of phenol degradation using wet air oxidation process. Phenol is a well known polluting molecule and therefore it is important having data of its behaviour during this process. A view cell is used for the experimental study, with an internal volume of 150 mL, able to reach pressures up to 30 MPa and temperatures up to 350°C. Concerning the thermodynamic phase equilibria, experimental and modelling results are obtained for different binary systems (water/nitrogen, water/air) and ternary system (water/nitrogen/phenol). The best model is the Predictive Soave Redlich Kwong one. This information is necessary to predict the composition of the gas phase during the process. It is also important for an implementation in a process simulation. The second part is dedicated to kinetics evaluation of the degradation of phenol. Different compounds have been detected using GC coupled with a MS. A kinetic scheme is deduced, taking into account the evolution of phenol, hydroquinones, catechol, resorcinol and acetic acid. The kinetic parameters are calculated for this scheme. These data are important to evaluate the evolution of the concentration of the different polluting molecules during the process. A simplified kinetic scheme, which can be easily implemented in a process simulation, is also determined for the direct degradation of phenol into H(2)O and CO(2). The Arrhenius law data obtained for the phenol disappearance are the following: k=1.8×10(6)±3.9×10(5)M(-1)s(-1) (pre-exponential factor) and E(a)=77±8 kJ mol(-1) (activation energy).

  16. Succinate overproduction: A case study of computational strain design using a comprehensive Escherichia coli kinetic model

    Directory of Open Access Journals (Sweden)

    Ali eKhodayari

    2015-01-01

    Full Text Available Computational strain design prediction accuracy has been the focus for many recent efforts through the selective integration of kinetic information into metabolic models. In general, kinetic model prediction quality is determined by the range and scope of genetic and/or environmental perturbations used during parameterization. In this effort, we apply the k-OptForce procedure on a kinetic model of E. coli core metabolism constructed using the Ensemble Modeling (EM method and parameterized using multiple mutant strains data under aerobic respiration with glucose as the carbon source. Minimal interventions are identified that improve succinate yield under both aerobic and anaerobic conditions to test the fidelity of model predictions under both genetic and environmental perturbations. Under aerobic condition, k-OptForce identifies interventions that match existing experimental strategies pointing at a number of unexplored flux redirections such as routing glyoxylate flux through the glycerate metabolism to improve succinate yield. Many of the identified interventions rely on the kinetic descriptions and would not be discoverable by a purely stoichiometric description. In contrast, under fermentative (anaerobic conditions, k-OptForce fails to identify key interventions including up-regulation of anaplerotic reactions and elimination of competitive fermentative products. This is due to the fact that the pathways activated under anaerobic conditions were not properly parameterized as only aerobic flux data were used in the model construction. This study shed light on the importance of condition-specific model parameterization and provides insight onto how to augment kinetic models so as to correctly respond to multiple environmental perturbations.

  17. Succinate Overproduction: A Case Study of Computational Strain Design Using a Comprehensive Escherichia coli Kinetic Model.

    Science.gov (United States)

    Khodayari, Ali; Chowdhury, Anupam; Maranas, Costas D

    2014-01-01

    Computational strain-design prediction accuracy has been the focus for many recent efforts through the selective integration of kinetic information into metabolic models. In general, kinetic model prediction quality is determined by the range and scope of genetic and/or environmental perturbations used during parameterization. In this effort, we apply the k-OptForce procedure on a kinetic model of E. coli core metabolism constructed using the Ensemble Modeling (EM) method and parameterized using multiple mutant strains data under aerobic respiration with glucose as the carbon source. Minimal interventions are identified that improve succinate yield under both aerobic and anaerobic conditions to test the fidelity of model predictions under both genetic and environmental perturbations. Under aerobic condition, k-OptForce identifies interventions that match existing experimental strategies while pointing at a number of unexplored flux re-directions such as routing glyoxylate flux through the glycerate metabolism to improve succinate yield. Many of the identified interventions rely on the kinetic descriptions that would not be discoverable by a purely stoichiometric description. In contrast, under fermentative (anaerobic) condition, k-OptForce fails to identify key interventions including up-regulation of anaplerotic reactions and elimination of competitive fermentative products. This is due to the fact that the pathways activated under anaerobic condition were not properly parameterized as only aerobic flux data were used in the model construction. This study shed light on the importance of condition-specific model parameterization and provides insight on how to augment kinetic models so as to correctly respond to multiple environmental perturbations.

  18. Thermogravimetric analysis and kinetic study on large particles of printed circuit board wastes.

    Science.gov (United States)

    Quan, Cui; Li, Aimin; Gao, Ningbo

    2009-08-01

    Pyrolysis of large printed circuit board (PCB) waste particle was conducted on a specially designed laboratory-scale thermobalance (Macro-TG) with sample loading of 30 g under dynamic nitrogen atmosphere. The effects of heating rate (10, 15, 20 and 25 degrees C min(-1)) and particle size (1 mm x 1 mm, 5 mm x 5 mm, 10 mm x 10 mm and 10 mm x 20 mm) were examined. To compare the different decomposition behavior of fine and large one, the thermal decomposition of PCB waste powder (approximately 5mg) was also performed on a thermogravimetric analyzer (common TG) under various heating rates (10, 15, 20 and 40 degrees C min(-1)) and particle size ranges (0.198-0.165 mm, 0.165-0.074 mm, 0.074-0.055 mm and 0.055-0.047mm). Experimental results show that large particle has a pyrolysis reaction retardancy compared to fine one. The distributed activation energy model was used to study the pyrolysis kinetics. It was found that during pyrolysis process, values of frequency factor (k(0)) changed with different activation energy (E) values. On common TG, the E values range from 156.95 to 319.37 kJ mol(-1) and k(0) values range from 2.67 x 10(13) to 2.24 x 10(27)s(-1). While, on Macro-TG, the range of E was 31.48-41.26 kJ mol(-1) and of the frequency factor was 19.80-202.67s(-1).

  19. Comparative Transport Studies of '1212' Superconductors

    Directory of Open Access Journals (Sweden)

    Albert Gapud

    1999-12-01

    Full Text Available HgBa2CaCu2O6+δ (Hg -1212 thin films were fabricated by exchanging the T1 cations in TlBa2CaCu2O7-δ (Tl-1212 thin films with Hg cations, causing a 30-K increase in Tc. To determine how this exchange effects such a Tc increase, the irreversibility lines, temperature dependence of critical current density, and temperature dependence of Hall angle ofHg-1212 and TI-1212 thin films were measured and then compared. The results strongly suggest that the Tc shift is caused by a doubling of charge carrier density.

  20. Kinetic studies on the Rhizomucor miehei lipase catalyzed esterification reaction of oleic acid with 1-butanol in a biphasic system

    NARCIS (Netherlands)

    Kraai, G.N.; Winkelman, J.G.M.; de Vries, Johannes; Heeres, H.J.

    2008-01-01

    The kinetics of the esterification of oleic acid with 1 -butanol catalyzed by free Rhizomucor miehei lipase in a biphasic system was studied in a batch reactor. The reaction appeared to proceed via a Ping Pong bi-bi mechanism with I -butanol inhibition. The kinetic constants of the model were

  1. Kinetic studies on the Rhizomucor miehei lipase catalyzed esterification reaction of oleic acid with 1-butanol in a biphasic system

    NARCIS (Netherlands)

    Kraai, G.N.; Winkelman, J.G.M.; de Vries, Johannes; Heeres, H.J.

    2008-01-01

    The kinetics of the esterification of oleic acid with 1 -butanol catalyzed by free Rhizomucor miehei lipase in a biphasic system was studied in a batch reactor. The reaction appeared to proceed via a Ping Pong bi-bi mechanism with I -butanol inhibition. The kinetic constants of the model were determ

  2. Genetic network models: a comparative study

    Science.gov (United States)

    van Someren, Eugene P.; Wessels, Lodewyk F. A.; Reinders, Marcel J. T.

    2001-06-01

    Currently, the need arises for tools capable of unraveling the functionality of genes based on the analysis of microarray measurements. Modeling genetic interactions by means of genetic network models provides a methodology to infer functional relationships between genes. Although a wide variety of different models have been introduced so far, it remains, in general, unclear what the strengths and weaknesses of each of these approaches are and where these models overlap and differ. This paper compares different genetic modeling approaches that attempt to extract the gene regulation matrix from expression data. A taxonomy of continuous genetic network models is proposed and the following important characteristics are suggested and employed to compare the models: inferential power; predictive power; robustness; consistency; stability and computational cost. Where possible, synthetic time series data are employed to investigate some of these properties. The comparison shows that although genetic network modeling might provide valuable information regarding genetic interactions, current models show disappointing results on simple artificial problems. For now, the simplest models are favored because they generalize better, but more complex models will probably prevail once their bias is more thoroughly understood and their variance is better controlled.

  3. Advertisement Analysis: A Comparative Critical Study

    Science.gov (United States)

    Abdelaal, Noureldin Mohamed; Sase, Amal Saleh

    2014-01-01

    This study aimed at analyzing two advertisements, and investigating how advertisers use discourse and semiotics to make people and customers buy into their ideas, beliefs, or simply their products. The two advertisements analyzed are beauty products which have been selected from internet magazines. The methodology adopted in this study is…

  4. EQUILIBRIUM, KINETIC, AND THERMODYNAMIC STUDIES OF LEAD (II BIOSORPTION ON SESAME LEAF

    Directory of Open Access Journals (Sweden)

    Li-e Liu,

    2012-06-01

    Full Text Available Sesame leaf, an agricultural solid waste, was used as low cost adsorbent for removal of Pb(II from aqueous solution in batch mode. The biosorbent was characterized by thermo-gravimetric analysis and Fourier transform infrared spectroscopy. The influences of phase contact time, solution pH, adsorbent dosage, and initial concentrations were investigated to optimize the conditions for maximum adsorption. The experimental data were analyzed by Langmuir, Freundlich, and Koble-Corrigan isotherm models. The Koble-Corrigan and Langmuir isotherms best represented the measured biosorption data. According to an evaluation using the Langmuir equation, the adsorption capacity of the biosorbent was found to be 279.86 mg g-1, which was higher or comparable to the adsorption capacity of various adsorbents reported in the literature. The kinetics of adsorption of Pb(II was evaluated by pseudo-first order, pseudo-second order, and intra-particle diffusion kinetic models. The experimental data fitted very well with the pseudo-second order kinetic model. The intra-particle diffusion model is not a dominant rate controlling mechanism in the sorption of Pb(II. Thermodynamic analysis showed that the adsorption was a spontaneous and endothermic process. The results indicated that sesame leaf can be used as an effective biosorbent for Pb(II removal from aqueous solutions.

  5. Mechanistic Investigations of Oxidation of Some Dipeptides by Sodium N-chloro-p-toluenesulfonamide in Alkaline Medium: A Kinetic Study

    Institute of Scientific and Technical Information of China (English)

    PUTTASWAMY; VAZ Nirmala; RAJENAHALLY VGOWDA Jagadeesh

    2008-01-01

    The kinetics of oxidation of five dipeptides (DPP) viz., glycylglycine (Gly-Gly), L-alanyl-L-alanine (Ala-Ala),L-valyl-L-valine (Val-Val), L-leucyl-L-leucine (Leu-Leu) and phenylglycyl-phenylglycine (Phg-Phg) by sodium N-chloro-p-toluenesuifonamide or chloramine-T (CAT) in NaOH medium was studied at 308 K. The reactions follow identical kinetics for all the dipeptides, being first-order dependence each on [CAT]o, [DPP]o and fractional-order on [OH-]. Addition of p-toluenesulfonamide or halide ions (CI- or Br-) has no significant effect on the rate of reaction. The reaction rate was found to increase with increase in ionic strength of the medium. The solvent isotope effect was studied using D2O. The activation parameters for the reaction were computed from Arrhenius plots. Equilibrium and decomposition constants were evaluated. The oxidation products of the dipeptides were identiffed as their corresponding aldehydes. An isokinetic relationship was observed with β=352 K, indicating that enthalpy factors control the reaction rate. CH3C6H4SO2NCl- of the oxidant has been postulated as the reactive oxidizing species. Under comparable experimental conditions, the rate of oxidation of the dipeptides increases in the order: Phg-Phg>Ala-Ala>Val-Val>Leu-Leu>Gly-Gly. The kinetics of oxidation of the dipeptides have also been compared with those of their corresponding monomer amino acids. The observed results have been explained by a plausible mechanism and the related rate law has been deduced.

  6. An experimental and kinetic modeling study of premixed nitroethane flames at low pressure

    DEFF Research Database (Denmark)

    Zhang, Kuiwen; Zhang, Lidong; Xie, Mingfeng

    2013-01-01

    An experimental and kinetic modeling study is reported on three premixed nitroethane/oxygen/argon flames at low pressure (4.655kPa) with the equivalence ratios (Φ) of 1.0, 1.5 and 2.0. Over 30 flame species were identified with tunable synchrotron vacuum ultraviolet photoionization mass spectrome......An experimental and kinetic modeling study is reported on three premixed nitroethane/oxygen/argon flames at low pressure (4.655kPa) with the equivalence ratios (Φ) of 1.0, 1.5 and 2.0. Over 30 flame species were identified with tunable synchrotron vacuum ultraviolet photoionization mass...... predictions have shown satisfactory agreement with the experimental results. Basing on the rate-of-production analysis, the reaction pathways that feature the combustion of nitroethane were revealed, including the primary decomposition of C–N bond fission, the oxidation of C2 and C1 hydrocarbons...

  7. DSC and curing kinetics study of epoxy grouting diluted with furfural -acetone slurry

    Science.gov (United States)

    Yin, H.; Sun, D. W.; Li, B.; Liu, Y. T.; Ran, Q. P.; Liu, J. P.

    2016-07-01

    The use of furfural-acetone slurry as active diluents of Bisphenol-A epoxy resin (DGEBA) groutings has been studied by dynamic and non-isothermal DSC for the first time. Curing kinetics study was investigated by non-isothermal differential scanning calorimetries at different heating rates. Activation enery (Ea) was calculated based on Kissinger and Ozawa Methods, and the results showed that Ea increased from 58.87 to 71.13KJ/mol after the diluents were added. The furfural-acetone epoxy matrix could cure completely at the theoretical curing temperature of 365.8K and the curing time of 139mins, which were determined by the kinetic model parameters.

  8. Physicochemical analysis and nonisothermal kinetic study of sertraline–lactose binary mixtures

    Directory of Open Access Journals (Sweden)

    Faranak Ghaderi

    2017-07-01

    Full Text Available In the present study the physicochemical stability of sertraline with lactose was evaluated in drug-excipient binary mixtures. Different physicochemical methods such as differential scanning calorimetry (DSC, Fourier-transform infrared spectroscopy, and mass spectrometry were applied to confirm the incompatibility. The final aim of this study was to evaluate the kinetic parameters using a fast and sensitive DSC method. Solid-state kinetic parameters were derived from nonisothermally stressed physical mixtures using different thermal models such as Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose. Overall, the instability of sertraline with lactose was successfully evaluated. Further confirmation was made by tracking the Maillard reaction product of sertraline and lactose by mass spectrometry. DSC scans provided important information about the stability of sertraline in solid-state condition and also revealed the related thermokinetic parameters in order to understand the nature of the chemical instability.

  9. Kinetics studies of d-glucose hydrogenation over activated charcoal supported platinum catalyst

    Science.gov (United States)

    Ahmed, Muthanna J.

    2012-02-01

    The kinetics of the catalytic hydrogenation of d-glucose to produce d-sorbitol was studied in a three-phase laboratory scale reactor. The hydrogenation reactions were performed on activated charcoal supported platinum catalyst in the temperature range 25-65°C and in a constant pressure of 1 atm. The kinetic data were modeled by zero, first and second-order reaction equations. In the operating regimes studied, the results show that the hydrogenation reaction was of a first order with respect to d-glucose concentration. Also the activation energy of the reaction was determined, and found to be 12.33 kJ mole-1. A set of experiment was carried out to test the deactivation of the catalyst, and the results show that the deactivation is slow with the ability of using the catalyst for several times with a small decrease in product yield.

  10. Batch and kinetic studies of Ni adsorption on highly humified Newfoundland peat

    Energy Technology Data Exchange (ETDEWEB)

    Asapo, E.S.; Coles, C.A. [Memorial Univ. of Newfoundland, St. John' s, NL (Canada). Faculty of Engineering and Applied Science

    2010-07-01

    Metal precipitation and neutralization processes are used to treat effluents produced by the metals industry. Nickel (Ni) mining in Newfoundland and Labrador (NL) may become a source of pollution if lime precipitation techniques are used to treat effluents as an accumulation of the metal in aquatic organisms and plants may pose a health risk to humans and animals. Studies have indicated that peat can be used as a low-cost adsorbent for metals. This study investigated the kinetic and sorption equilibria parameters for the uptake of Ni with saprist NL peat. The aim of the study was to determine how the peat can be used to remove metals from the Ni mining effluents. A pseudo second order kinetic model with regression coefficients characterized kinetic parameters at a solution pH of 5.5 for peat doses of 4, 10, 21 and 40 g per litre with solution concentrations of 24, 50, 125 and 200 mg per litre. Langmuir and Freundlich isotherm equilibrium sorption parameters were determined. The study demonstrated that over 90 percent of Ni removal was obtained using the Langmuir isotherm. The adsorption process was significantly influenced by the peat dose and the initial metal concentration.12 refs., 4 tabs.

  11. ELECTRODEPOSITION OF COPPER IONS ON FIXED BED ELECTRODES: KINETIC AND HYDRODYNAMIC STUDY

    Directory of Open Access Journals (Sweden)

    L.A.M. Ruotolo

    2002-03-01

    Full Text Available The kinetic and hydrodynamic behaviour of a fixed-bed electrochemical reactor was studied in terms of current efficiency (CE and energy efficiency (EE. In the kinetic experiments the effects of fixed bed thickness (L, current density (i and initial concentration of copper (C0 were studied. In the hydrodynamic experiments the permeability (k of the electrode and the coefficient for inertial forces (c were also studied as functions of the applied current density. At low current densities and bed thicknesses greater than 1.0 cm, negative CE and EE were observed as a consequence of the dissolution of the porous matrix. At high current densities low CE and EE were observed and a powdery deposit was formed on the surface of the particles. From the results of the kinetic study bed thickness and the range of current densities employed in the hydrodynamic experiments were chosen. In these experiments the electrodeposition process continued until the whole electrode had been clogged and no more electrolyte could pass through it. The relationship between pressure drop and flow rate was well described by the Forchheimer equation. It was observed that the reduction in porosity due to copper electrodeposition causes the flow rate to decrease because of the decrease in electrode permeability, but it had no influence on current efficiency.

  12. COMPARATIVE STUDY OF LIGHT SOURCES FOR HOUSEHOLD

    Directory of Open Access Journals (Sweden)

    Andrzej PAWLAK

    2017-01-01

    Full Text Available The article describes test results that provided the ground to define and evaluate basic photometric, colorimetric and electric parameters of selected, widely available light sources, which are equivalent to a traditional incandescent 60-Watt light bulb. Overall, one halogen light bulb, three compact fluorescent lamps and eleven LED light sources were tested. In general, it was concluded that in most cases (branded products, in particular the measured and calculated parameters differ from the values declared by manufacturers only to a small degree. LED sources prove to be the most beneficial substitute for traditional light bulbs, considering both their operational parameters and their price, which is comparable with the price of compact fluorescent lamps or, in some instances, even lower.

  13. Earthquake Correlations and Networks- A Comparative Study

    CERN Document Server

    G., T R Krishna Mohan P

    2010-01-01

    We quantify the correlation between earthquakes and use the same to distinguish between relevant causally connected earthquakes. Our correlation metric is a variation on the one introduced by Baiesi and Paczuski (2004). A network of earthquakes is constructed, which is time ordered and with links between the more correlated ones. Recurrences to earthquakes are identified employing correlation thresholds to demarcate the most meaningful ones in each cluster. Data pertaining to three different seismic regions, viz. California, Japan and Himalayas, are comparatively analyzed using such a network model. The distribution of recurrence lengths and recurrence times are two of the key features analyzed to draw conclusions about the universal aspects of such a network model. We find that the unimodal feature of recurrence length distribution, which helps to associate typical rupture lengths with different magnitude earthquakes, is robust across the different seismic regions. The out-degree of the networks shows a hub ...

  14. Nonlinear analysis of RED - a comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Kai; Wang Xiaofan E-mail: xfwang@sjtu.edu.cn; Xi Yugeng

    2004-09-01

    Random Early Detection (RED) is an active queue management (AQM) mechanism for routers on the Internet. In this paper, performance of RED and Adaptive RED are compared from the viewpoint of nonlinear dynamics. In particular, we reveal the relationship between the performance of the network and its nonlinear dynamical behavior. We measure the maximal Lyapunov exponent and Hurst parameter of the average queue length of RED and Adaptive RED, as well as the throughput and packet loss rate of the aggregate traffic on the bottleneck link. Our simulation scenarios include FTP flows and Web flows, one-way and two-way traffic. In most situations, Adaptive RED has smaller maximal Lyapunov exponents, lower Hurst parameters, higher throughput and lower packet loss rate than that of RED. This confirms that Adaptive RED has better performance than RED.

  15. Stability and kinetic studies of supported ionic liquid phase catalysts for hydroformylation of propene

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco;

    2005-01-01

    Supported ionic liquid phase (SILP) catalysts have been studied with regard to their long-term stability in the continuous gas-phase hydroformylation of propene. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate concentration, and residence time...... exceeded 200 h time on stream with no loss in selectivity. A small decrease in activity could be compensated by a vacuum procedure regaining the initial activity....

  16. Real-time study of protein adsorption kinetics in porous silicon.

    Science.gov (United States)

    Lasave, Liliana C; Urteaga, Raúl; Koropecki, Roberto R; Gonzalez, Verónica D; Arce, Roberto D

    2013-11-01

    This paper presents an optical method for real-time monitoring of protein adsorption using porous silicon self-supported microcavities as a label-free detection platform. The study combines an experimental approach with a physical model for the adsorption process. The proposed model agrees well with experimental observations, and provides information about the kinetics of diffusion and adsorption of proteins within the pores, which will be useful for future experimental designs.

  17. A kinetic study of jack-bean urease denaturation by a new dithiocarbamate bismuth compound

    Science.gov (United States)

    Menezes, D. C.; Borges, E.; Torres, M. F.; Braga, J. P.

    2012-10-01

    A kinetic study concerning enzymatic inhibitory effect of a new bismuth dithiocarbamate complex on jack-bean urease is reported. A neural network approach is used to solve the ill-posed inverse problem arising from numerical treatment of the subject. A reaction mechanism for the urease denaturation process is proposed and the rate constants, relaxation time constants, equilibrium constants, activation Gibbs free energies for each reaction step and Gibbs free energies for the transition species are determined.

  18. PWO crystals for CMS electromagnetic calorimeter : studies of the radiation damage kinetics

    OpenAIRE

    Drobychev, G.; Auffray, E.; Dormenev, V.; Korzhik, M; Lecoq, P.; Lopatic, A.; Nédélec, P.; Peigneux, J. P.; D. Sillou

    2005-01-01

    Kinetics of radiation damage of the PWO crystals under irradiation and recovery were studied. Crystals were irradiated with dose corresponding to average one expected in the electromagnetic calorimeter (working dose irradiation). Radiation damage and recovery were monitored through measurements of PWO optical transmission. An approach is proposed which allows evaluating the influence of the PWO crystals properties on the statistical term in the energy resolution of the electromagnetic calorim...

  19. A comparative study of microbiological and physicochemical ...

    African Journals Online (AJOL)

    Ethiopian Journal of Environmental Studies and Management ... Rwandan Water and Sanitation Corporation ltd (WASAC) water branches: Kimisagara WASAC water ... strategy for better water quality especially along the distribution network.

  20. New approaches to the kinetic study of alcoholic fermentation by chromatographic techniques.

    Science.gov (United States)

    Lainioti, Georgia Ch; Karaiskakis, George

    2013-09-01

    The kinetics of the fermentation process has gained increasing interest, not only in the scientific community, but in the industrial world as well. Information concerning the improvement of batch fermentation performance may potentially be valuable for the designing of scale-up processes. Intensive studies have been conducted with the use of various chromatographic techniques, such as conventional gas chromatography, reversed-flow gas chromatography (RFGC), high-performance liquid chromatography, field-flow fractionation and others. In the present study, specific focus is placed on the employment of RFGC, a method that can successfully be applied for the determination of physicochemical quantities, such as reaction rate constants and activation energies, at each phase of the alcoholic fermentation. In contrast to conventional chromatographic techniques, RFGC can lead to substantial information referring to the evaluation of fermentation kinetics at any time of the process. Moreover, gravitational field-flow fractionation, a sub-technique of field-flow fractionation, presents the ability to monitor the proliferation of Saccharomyces cerevisiae cells through their elution profiles that can be related to the different cell growth stages. The combination of the two techniques can provide important information for kinetic study and the distinction of the growth phases of yeast cell proliferation during alcoholic fermentations conducted under different environmental conditions.

  1. Characterization and kinetics study of off-gas emissions from stored wood pellets.

    Science.gov (United States)

    Kuang, Xingya; Shankar, Tumuluru Jaya; Bi, Xiaotao T; Sokhansanj, Shahab; Lim, C Jim; Melin, Staffan

    2008-11-01

    The full potential health impact from the emissions of biomass fuels, including wood pellets, during storage and transportation has not been documented in the open literature. The purpose of this study is to provide data on the concentration of CO(2), CO and CH(4) from wood pellets stored in sealed vessels and to develop a kinetic model for predicting the transient emission rate factors at different storage temperatures. Five 45-l metal containers (305 mm diameter by 610 mm long) equipped with heating and temperature control devices were used to study the temperature effect on the off-gas emissions from wood pellets. Concurrently, ten 2-l aluminum canisters (100 mm diameter by 250 mm long) were used to study the off-gas emissions from different types of biomass materials. Concentrations of CO(2), CO and CH(4) were measured by a gas chromatograph as a function of storage time and storage temperature. The results showed that the concentrations of CO, CO(2) and CH(4) in the sealed space of the reactor increased over time, fast at the beginning but leveling off after a few days. A first-order reaction kinetics fitted the data well. The maximum concentration and the time it takes for the buildup of gas concentrations can be predicted using kinetic equations.

  2. Equilibrium, kinetic and thermodynamic study of the biosorption of uranium onto Cystoseria indica algae

    Energy Technology Data Exchange (ETDEWEB)

    Khani, M.H. [Department of Chemical Engineering, Faculty of Engineering, University of Tarbiat Modares, P.O. Box 14115-111, Tehran (Iran, Islamic Republic of); Nuclear Science Research school, Nuclear Science and Technology Research Institute, P.O. Box 11365, 8486 Tehran (Iran, Islamic Republic of)], E-mail: mhkhani@modares.ac.ir; Keshtkar, A.R.; Ghannadi, M. [Nuclear Science Research school, Nuclear Science and Technology Research Institute, P.O. Box 11365, 8486 Tehran (Iran, Islamic Republic of); Pahlavanzadeh, H. [Department of Chemical Engineering, Faculty of Engineering, University of Tarbiat Modares, P.O. Box 14115-111, Tehran (Iran, Islamic Republic of)

    2008-02-11

    Biosorption equilibrium, kinetics and thermodynamics of binding of uranium ions to Cystoseria indica were studied in a batch system with respect to temperature and initial metal ion concentration. Algae biomass exhibited the highest uranium uptake capacity at 15 deg. C at an initial uranium ion concentration of 500 mg l{sup -1} and an initial pH of 4. Biosorption capacity increased from 198 to 233 mg g{sup -1} with an decrease in temperature from 45 to 15 deg. C at this initial uranium concentration. The Langmuir isotherm model were applied to experimental equilibrium data of uranium biosorption depending on temperature. Equilibrium data fitted very well to the Langmuir model C. indica algae in the studied concentration range of Uranium ions at all the temperatures studied. The saturation type kinetic model was applied to experimental data at different temperatures changing from 15 to 45 deg. C to describe the batch biosorption kinetics assuming that the external mass transfer limitations in the system can be neglected and biosorption is chemical sorption controlled. The activation energy of biosorption (E{sub A}) was determined as -6.15 using the Arrhenius equation. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of biosorption ({delta}G{sup o}, {delta}H{sup o} and {delta}S{sup o}) were also evaluated.

  3. SOYBEAN (GLYCINE MAX UREASE: STEADY STATE KINETICS, STABILITY AND THERMAL INACTIVATION STUDIES

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar

    2017-06-01

    Full Text Available The soybean (Glycine max urease was characterized with respect to kinetic parameters, stability studies and thermal inactivation. The stability temperature and stability pH of the purified urease was found to be 4 °C and 7.6, respectively. The optimum pH and optimum temperature were 7.0 oC and 65 oC, respectively. The energy of activation (Ea was 15.40 kJ/mol. Further, the Km and Vmax were determined by Lineweaver Burk plot and the values were 2.70 ± 0.10 mM and 2.85 x102 µmol NH3/min/mg protein,respectively. Thermal inactivation studies at 65 oC, revealed the mono-phasic kinetics, which indicated the loss in activity in single phase. However, at higher temperatures (70 oC, 75 oC and 77 oC, the kinetic pattern was mainly bi-phasic. At 80 oC, there was complete loss in activity thereby showing the denaturation of enzyme. Thermal inactivation studies strongly support the oligomeric nature of urease.

  4. Studying the Kinetics of n-Butyl-Cyanoacrylate Tissue Adhesive and Its Oily Mixtures

    Science.gov (United States)

    Nedvedova, Marie; Kresalek, Vojtech; Vaskova, Hana; Provaznik, Ivo

    2016-10-01

    This study deals with the measurement of the kinetics of tissue adhesives used for supporting the hemostasis and wound closure during surgical intervention. There are available several types of adhesives of different composition which is closely related with their application. When selecting an appropriate adhesive, the time of curing could play an important role because some applications may require very fast polymerization for prompt vessel or wound closure; conversely, some situations need slower solidification because of longer manipulation with the glue during surgery. The terahertz time-domain spectroscopy is used for studying the kinetics of the n-butyl-cyanoacrylate glue in this study. An oily substance is added to the glue samples to slow the reaction rate. The technique of attenuated total reflection is used in this application; the defined amount of glue sample or its mixture is applied on the silicon crystal and the terahertz response is measured in time. This time dependences are analyzed to find time constants for mathematical description of the glue kinetics. Further, the investigated samples were analyzed using light microscopy and Raman spectroscopy for description of the structures and compositions.

  5. Domain-growth kinetics and aspects of pinning: A Monte Carlo simulation study

    DEFF Research Database (Denmark)

    Castán, T.; Lindgård, Per-Anker

    1991-01-01

    By means of Monte Carlo computer simulations we study the domain-growth kinetics after a quench across a first-order line to very low and moderate temperatures in a multidegenerate system with nonconserved order parameter. The model is a continuous spin model relevant for martensitic transformati...... the continuous-spin model is reduced to a discrete Potts-like model, with the same parameters, the exponent is found to be consistent with the classical Allen-Cahn exponent n = 1/2.......By means of Monte Carlo computer simulations we study the domain-growth kinetics after a quench across a first-order line to very low and moderate temperatures in a multidegenerate system with nonconserved order parameter. The model is a continuous spin model relevant for martensitic...... transformations, surface reconstructions, and magnetic transitions. No external impurities are introduced, but the model has a number of intrinsic, annealable pinning mechanisms, which strongly influences the growth kinetics. It allows a study of pinning effects of three kinds: (a) pinning of domain walls...

  6. Advertisement Analysis: A Comparative Critical Study

    Directory of Open Access Journals (Sweden)

    Noureldin Mohamed Abdelaal

    2014-12-01

    Full Text Available This study aimed at analyzing two advertisements, and investigating how advertisers use discourse and semiotics to make people and customers buy into their ideas, beliefs, or simply their products. The two advertisements analyzed are beauty products which have been selected from internet magazines. The methodology adopted in this study is qualitative method. The first advertisement is analyzed qualitatively in terms of content; there was no focus on a specific theoretical frame work, while the second advertisement analysis is based on Fairclough’s framework, the critical discourse analysis framework.

  7. Annual Journal citation indices: a comparative study

    CERN Document Server

    Khaleque, Abdul; Sen, Parongama

    2016-01-01

    We study the statistics of citations made to the indexed Science journals in the Journal Citation Reports during the period 2004-2013 using different measures. We consider different measures which quantify the impact of the journals. To our surprise, we find that the apparently uncorrelated measures, even when defined in an arbitrary manner, show strong correlations. This is checked over all the years considered. Impact factor being one of these measures, the present work raises the question whether it is actually a nearly perfect index as claimed often. In addition we study the distributions of the different indices which also behave similarly.

  8. Child Labor in Africa: A Comparative Study

    DEFF Research Database (Denmark)

    Canagarajah, Sudharshan; Nielsen, Helena Skyt

    2001-01-01

    This paper analyzes the determinants of child labor in Africa as inferred from recent empirical studies. The empirical analysis is based upon five country studies undertaken in three different African countries, namely Côte d'Ivoire, Ghana, and Zambia. Some support is found for the popular belief...... of poverty as a determinant of child labor, however other determinants are of similar importance. Among school costs, transportation costs have the greatest effect on child labor and school attendance, whereas the hypothesis of imperfect capital markets and that of household composition generally find some...

  9. Child Labor in Africa: A Comparative Study

    DEFF Research Database (Denmark)

    Nielsen, Helena Skyt; Canagarajah, Sudharshan

    1999-01-01

    This paper analyzes the determinants of child labor in Africa as inferred from recent empirical studies. The empirical analysis is based upon five country studies undertaken in three different African countries, namely Côte d'Ivoire, Ghana, and Zambia. Some support is found for the popular belief...... of poverty as a determinant of child labor, however other determinants are of similar importance. Among school costs, transportation costs have the greatest effect on child labor and school attendance, whereas the hypothesis of imperfect capital markets and that of household composition generally find some...

  10. Annual Journal Citation Indices: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Abdul Khaleque

    2016-06-01

    Full Text Available We study the statistics of citations made to the indexed Science journals in the Journal Citation Reports during the period 2004-2013 using different measures. We consider different measures which quantify the impact of the journals. To our surprise, we find that the apparently uncorrelated measures, even when defined in an arbitrary manner, show strong correlations. This is checked over all the years considered. Impact factor being one of these measures, the present work raises the question whether it is actually a nearly perfect index as claimed often. In addition, we study the distributions of the different indices which also behave similarly.

  11. A Comparative Comment on the Case Studies

    DEFF Research Database (Denmark)

    Kjeldsen, Christian Christrup; Ley, Thomas; Jensen, Niels Rosendal;

    2012-01-01

    Denne konklusion sammenfatter hovedtrækkene af de gennemførte case studies i WorkAble-projektet. Vigtige pointer er, at unge på tværs af de forskellige case studies har vanskeligt ved at blive hørt og taget alvorligt. I stedet spises de af med "realistisk vejledning" eller dårlige uddannelses- og...... arbejdstilbud. Konklusionen foreslår at give unge mere tid til at træffe de alvorlige valg vedr. deres fremtid ved at indføre et refugium, som i tankegang minder om Eriksons ungdomsmoratorium....

  12. Thermogravimetric Analysis and Kinetic Study on Pyrolysis of Veteri-narian Solid Waste

    Directory of Open Access Journals (Sweden)

    Andrés Felipe Rojas González

    2016-10-01

    Full Text Available Context: Institutional waste from clinical centers can be classified as those coming from health institutions dedicated to human attention and those coming from centers for animal veterinary care. The latter are mainly hazardous wastes, hence their disposal requires incineration. Most of such waste is organic, and it is possible, therefore, to take advantage of their energetic power in combustion or pyrolysis processes. This work is motivated because no literature was found on the pyrolysis kinetics veterinary waste, as this kind of studies are mainly focused on hospital waste of human health care. Method: The kinetics of pyrolysis is characterized and studied by means of thermogravimetric analysis of 6 major veterinary waste (gauze, cotton swabs, cotton, nails, hair, plastic syringes. The characterization is performed by proximate and elemental analysis, and thermogravimetric analysis. Reactivity characteristics and pyrolytic capability of wastes are established. The kinetics study on pyrolysis was carried out by determining the kinetic triplet by isoconversional Starink method. Results: It was established that the pyrolysis index increases with the heating rate and that the thermal degradation depends on the material type of the waste. Similarly, it was found that the temperature (ΔT = Tf - Ti for the thermal decomposition of veterinary waste is: ΔTnails> ΔThair > ΔTcotton swabs > ΔTgauze > ΔTcotton > ΔTplastic syringes; the activation energy is Enails> E hair > Eplastic syringes > Ecotton swabs > E gauze > Ecotton, and the reaction order is: n hair > nnails > ncotton swabs > ncotton > n gauze > n plastic syringes. Conclusions: These results suggest the possibility of using veterinary wastes for power generation, providing an alternative for sustainable energy development to cities in continuous growth, from both, energetic and environmental points of view.

  13. Kinetic study and growth behavior of template-based electrodeposited platinum nanotubes controlled by overpotential

    Energy Technology Data Exchange (ETDEWEB)

    Yousefi, E. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave., P.O.Box 11155-9466, Tehran (Iran, Islamic Republic of); Dolati, A., E-mail: dolati@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave., P.O.Box 11155-9466, Tehran (Iran, Islamic Republic of); Imanieh, I. [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave., P.O.Box 11155-9466, Tehran (Iran, Islamic Republic of); Yashiro, H.; Kure-Chu, S.-Z. [Department of Chemistry and Bioengineering, Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551 (Japan)

    2017-02-01

    Platinum nanotubes (PtNTs) are fabricated by potentiostatic electrodeposition at various overpotentials (−200 up to −400 mV versus SCE) in polycarbonate templates (PCTs) with pore diameter of 200 nm in a solution containing 5 mM H{sub 2}PtCl{sub 6} and 0.1 M H{sub 2}SO{sub 4}. The synthesized PtNTs are characterized by field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The electrochemical growth mechanism within nanoscopic pores and the relationship between morphological variations and kinetic parameters are investigated for the first time. It is shown that more porous structure of nanotubes forms at high overpotentials possibly due to preferably nucleation. The kinetics of electrodeposition process is studied by electrochemical techniques such as voltammetry and chronoamperometry. The linear diffusion coefficient at the early stage of the deposition and the radial diffusion coefficients at steady state regime are calculated as D = 8.39 × 10{sup −5} and 2.33–13.26 × 10{sup −8} cm{sup 2}/s, respectively. The synthesized PtNT electrode is tested as electrocatalyst for hydrogen peroxide oxidation in phosphate buffer solution (PBS) and shows a sensitivity as high as 2.89 mA per 1 μM that is an indication to its enlarged electrochemical surface area. - Highlights: • PtNT is electrodeposited in a 3-aminopropyltrimethoxysilane-modified PCT. • The electrochemical growth mechanism within nanoscopic pores is discussed. • The kinetics of PtNT electrodeposition is studied based on models for UME arrays. • Relationship between morphological variations vs. kinetic parameters is studied.

  14. Comparative Anticonvulsant Study of Epoxycarvone Stereoisomers

    Directory of Open Access Journals (Sweden)

    Paula Regina Rodrigues Salgado

    2015-10-01

    Full Text Available Stereoisomers of the monoterpene epoxycarvone (EC, namely (+-cis-EC, (−-cis-EC, (+-trans-EC, and (−-trans-EC, were comparatively evaluated for anticonvulsant activity in specific methodologies. In the pentylenetetrazole (PTZ-induced anticonvulsant test, all of the stereoisomers (at 300 mg/kg increased the latency to seizure onset, and afforded 100% protection against the death of the animals. In the maximal electroshock-induced seizures (MES test, prevention of tonic seizures was also verified for all of the isomers tested. However, the isomeric forms (+ and (−-trans-EC showed 25% and 12.5% inhibition of convulsions, respectively. In the pilocarpine-induced seizures test, all stereoisomers demonstrated an anticonvulsant profile, yet the stereoisomers (+ and (−-trans-EC (at 300 mg/kg showed a more pronounced effect. A strychnine-induced anticonvulsant test was performed, and none of the stereoisomers significantly increased the latency to onset of convulsions; the stereoisomers probably do not act in this pathway. However, the stereoisomers (+-cis-EC and (+-trans-EC greatly increased the latency to death of the animals, thus presenting some protection. The four EC stereoisomers show promise for anticonvulsant activity, an effect emphasized in the isomers (+-cis-EC, (+-trans-EC, and (−-trans-EC for certain parameters of the tested methodologies. These results serve as support for further research and development of antiepileptic drugs from monoterpenes.

  15. LES versus DNS: A comparative study

    Science.gov (United States)

    Shtilman, L.; Chasnov, J. R.

    1992-01-01

    We have performed Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) of forced isotropic turbulence at moderate Reynolds numbers. The subgrid scale model used in the LES is based on an eddy viscosity which adjusts instantaneously the energy spectrum of the LES to that of the DNS. The statistics of the large scales of the DNS (filtered DNS field or fDNS) are compared to that of the LES. We present results for the transfer spectra, the skewness and flatness factors of the velocity components, the PDF's of the angle between the vorticity and the eigenvectors of the rate of strain, and that between the vorticity and the vorticity stretching tensor. The above LES statistics are found to be in good agreement with those measured in the fDNS field. We further observe that in all the numerical measurements, the trend was for the LES field to be more gaussian than the fDNS field. Future research on this point is planned.

  16. Bilingual Language Proficiency : A comparative study

    NARCIS (Netherlands)

    Duarte, Joana

    2011-01-01

    his book investigates the role native language plays in the process of acquiring a second language within a bilingual educational model. The research presented is based on a 2 year longitudinal study of students in a bilingual school. Particular attention is paid to the development of academic

  17. A comparative study on permissiveness toward euthanasia

    NARCIS (Netherlands)

    Verbakel, C.M.C.; Jaspers, E.

    2010-01-01

    This study explores explanations for the approval of euthanasia by assessing differences among individuals and countries, using four main arguments used by opponents and proponents in the public debate over euthanasia. We performed multilevel analysis on data from thirty-three countries, obtained fr

  18. A comparative study on permissiveness toward euthanasia

    NARCIS (Netherlands)

    Verbakel, C.M.C.; Jaspers, E.

    2010-01-01

    This study explores explanations for the approval of euthanasia by assessing differences among individuals and countries, using four main arguments used by opponents and proponents in the public debate over euthanasia. We performed multilevel analysis on data from thirty-three countries, obtained

  19. Metacognition and Group Differences: A Comparative Study

    Science.gov (United States)

    Al-Hilawani, Yasser A.

    2014-01-01

    In this study, metacognition refers to performing visual analysis and discrimination of real life events and situations in naïve psychology, naïve physics, and naïve biology domains. It is used, along with measuring reaction time, to examine differences in the ability of four groups of students to select appropriate pictures that correspond with…

  20. Children's Friendship Development: A Comparative Study

    Science.gov (United States)

    Yu, SeonYeong; Ostrosky, Michaelene M.; Fowler, Susan A.

    2011-01-01

    Establishing friendships is an important developmental goal of early childhood, but little research has addressed ways in which parents support the friendship development of their young children with disabilities. The purpose of this survey study was to explore the support strategies that parents use to facilitate their children's friendships.…