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1
Khaloo, Shokooh Sadat, Amir Hossein Matin, Sahar Sharifi, Masoumeh Fadaeinia, Narges Kazempour, and Shaghayegh Mirzadeh. "Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell." Water Science and Technology 65, no. 8 (April 1, 2012): 1341–49. http://dx.doi.org/10.2166/wst.2012.767.
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The application of almond shell as a low cost natural adsorbent to remove Hg2+ from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg2+ uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG0, ΔH0 and ΔS0, indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg2+ removal from a synthetic effluent.
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Ervin, J. S., and S. P. Heneghan. "The Meaning of Activation Energy and Reaction Order in Autoaccelerating Systems." Journal of Engineering for Gas Turbines and Power 120, no. 3 (July 1, 1998): 468–73. http://dx.doi.org/10.1115/1.2818168.
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Global reaction mechanisms and rate constants are commonly used in computational fluid dynamics models that incorporate chemical reactions to study aviation fuel thermal and oxidative thermal stability. Often these models are calibrated using one set of conditions, such as flow rate and temperature. New conditions are then calculated by extrapolation using the global expressions. A close inspection of the origin of global oxidation rate constants reveals that in systems that undergo autocatalysis or auto inhibition, a simple overall global activation energy and reaction order are not good descriptors of the reaction process. Furthermore, pseudo-detailed chemical kinetic modeling of a fuel that experiences autocatalysis shows that the observed reaction order for oxygen consumption varies with initial oxygen concentration, extent of reaction, and temperature. Thus, a simple global rate expression used to describe oxygen consumption in an autoaccelerating system is insufficient to allow extrapolation to different temperature or time regimes.
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Talukdar, R. K., L. Zhu, K. J. Feierabend, and J. B. Burkholder. "Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>2</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>." Atmospheric Chemistry and Physics Discussions 11, no. 6 (June 27, 2011): 18211–48. http://dx.doi.org/10.5194/acpd-11-18211-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3+ (CHO)2 (k3) and NO3+ CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (3.7 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (4.1 ± 1.2) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.
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Talukdar, R. K., L. Zhu, K. J. Feierabend, and J. B. Burkholder. "Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>3</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>." Atmospheric Chemistry and Physics 11, no. 21 (November 2, 2011): 10837–51. http://dx.doi.org/10.5194/acp-11-10837-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3 + (CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.
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Yusuf Ibrahim, Yusuf Usman Jibrin, Zaharaddeen Muhammad, and Mujahid Abubakar. "PHOTOCATALYTIC OPTIMIZATION OF MR DYE BY K-ZnO AND ZnO CATALYSTS UNDER VISIBLE IRRADIATION." FUDMA JOURNAL OF SCIENCES 4, no. 4 (June 12, 2021): 67–76. http://dx.doi.org/10.33003/fjs-2020-0404-408.
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The lucubration on the visible light methyl red (MR) degradation using K-ZnO and undoped ZnO photo catalyst was investigated. The successive formation of K-ZnO was ascertained by several techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and UV-Visible spectrophotometer and solid state UV-Vis band gap energy determination by comparing the Kubelka-Monk equation with Tauc equation and the energy band gap was calculated to be 3.28ev. The influence of reaction variables such as MR concentration, reaction pH, catalyst loadings and temperature have been investigated for both process. The kinetics model was developed for both doped and undoped ZnO photocatalyst using pseudo first and second order kinetics, the result indicated that both doped and undoped ZnO followed pseudo first order kinetics due to higher correlation coefficient (R2) value of 0.985 and 0.922 with rate constant (k) of 0.026 min-1 and 0.062 min-1, respectively. Based on the rate constant value (k) obtained at different reaction temperatures, the Arrhenius expression was derived. The derived activation energy (Ea) for the degradation of MR by K-ZnO photocatalysis was 32.109x103JK-1. The optimum condition for K-ZnO showed nearly complete degradation (95%) of the dye molecules with slightly higher degradation efficiency compares to ZnO (91%).
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Mahaboob, B., J. PeterPraveen, J. Ravi Sankar, B. Venkateswarlu, and C. Narayana. "A Memoir on Nonlinear Regression Model and its Pseudo Model." International Journal of Engineering & Technology 7, no. 4.10 (October 2, 2018): 995. http://dx.doi.org/10.14419/ijet.v7i4.10.26643.
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The main objective of this article is to specify a nonlinear regression model, formulate the assumptions on them and aquire its linear pseudo model. A model may be considered a mathematical description of a physical, chemical or biological state or process. Many models used in applied mathematics and Mathematical statistics are nonlinear in nature one of the major topics in the literature of theoretical and applied mathematics is the estimation of parameters of nonlinear regression models. A perfect model may have to many parameters to be useful. Nonlinear regression models have been intensively studied in the last three decades. Junxiong Lin et.al [1] , in their paper, compared best –fit equations of linear and nonlinear forms of two widely used kinetic models, namely pseudo-first order and pseudo=second-order equations. K. Vasanth kumar [2], in his paper, proposed five distinct models of second order pseudo expression and examined a comparative study between method of least squares for linear regression models and a trial and error nonlinear regression procedures of deriving pseudo second order rare kinetic parameters. Michael G.B. Blum et.al [3] proposed a new method which fits a nonlinear conditional heteroscedastic regression of the parameter on the summary statistics and then adaptively improves estimation using importance sampling.
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Rabehasaina, Landy, and Bruno Sericola. "A second-order Markov-modulated fluid queue with linear service rate." Journal of Applied Probability 41, no. 03 (September 2004): 758–77. http://dx.doi.org/10.1017/s0021900200020532.
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We consider an infinite-capacity second-order fluid queue governed by a continuous-time Markov chain and with linear service rate. The variability of the traffic is modeled by a Brownian motion and a local variance function modulated by the Markov chain and proportional to the fluid level in the queue. The behavior of this second-order fluid-flow model is described by a linear stochastic differential equation, satisfied by the transient queue level. We study the transient level's convergence in distribution under weak assumptions and we obtain an expression for the stationary queue level. For the first-order case, we give a simple expression of all its moments as well as of its Laplace transform. For the second-order model we compute its first two moments.
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Rabehasaina, Landy, and Bruno Sericola. "A second-order Markov-modulated fluid queue with linear service rate." Journal of Applied Probability 41, no. 3 (September 2004): 758–77. http://dx.doi.org/10.1239/jap/1091543424.
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We consider an infinite-capacity second-order fluid queue governed by a continuous-time Markov chain and with linear service rate. The variability of the traffic is modeled by a Brownian motion and a local variance function modulated by the Markov chain and proportional to the fluid level in the queue. The behavior of this second-order fluid-flow model is described by a linear stochastic differential equation, satisfied by the transient queue level. We study the transient level's convergence in distribution under weak assumptions and we obtain an expression for the stationary queue level. For the first-order case, we give a simple expression of all its moments as well as of its Laplace transform. For the second-order model we compute its first two moments.
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Rusdiarso, Bambang, Rahmat Basuki, and Sri Juari Santosa. "Evaluation of Lagergren Kinetics Equation by Using Novel Kinetics Expression of Sorption of Zn2+ onto Horse Dung Humic Acid (HD-HA)." Indonesian Journal of Chemistry 16, no. 3 (March 12, 2018): 338. http://dx.doi.org/10.22146/ijc.21151.
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Extraction and purification of humic acid from dry horse dung powder (HD-HA) was performed successfully and the purified HD-HA was then applied as sorbent to adsorb Zn2+. Extraction and purification were performed based on procedure of Stevenson (1994) under atmospheric air. Parameters investigated in this work consist of effect of medium sorption acidity, sorption rate (ka) and desorption rate constant (kd), Langmuir (monolayer) and Freundlich (multilayer) sorption capacities, and energy (E) of sorption. The ka and kd were determined according to the kinetic model of second order sorption reaching equilibrium, monolayer sorption capacity (b) and energy (E) were determined according to Langmuir isotherm model, and multilayer sorption capacity (B) was determined based on Freundlich isotherm model. Sorption of Zn2+ on purified HD-HA was maximum at pH 5.0. The novel kinetic expression resulted from proposed kinetic model has been shown to be more applicable than the commonly known Lagergren equation obtained from the pseudo-first order sorption model. The application of the equation revealed that the intercept of Lagergren equation, ln qe was more complex function of initial concentration of Zn2+ (a), Langmuir sorption capacity (b), and sorbed Zn2+ at equilibrium (xe).
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Liu, Ting Yi, Zhong Liang Wang, and Xiao Xing Yan. "Enhanced Cr(VI) Removal from Landfill Leachates Using Nanoscale Zero-Valent Iron." Advanced Materials Research 905 (April 2014): 12–18. http://dx.doi.org/10.4028/www.scientific.net/amr.905.12.
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Nanoscale zero-valent iron modified by citric acid (m-NZVI) was used to remove hexavalent chromium (Cr (VI)) from landfill leachates. Citric acid was useful to enhance the dispersion of NZVI. The results demonstrated that the m-NZVI particles were uniform with a mean diameter of 45.6 nm and the specific surface area was about 22.8 m2/g. The Cr (VI) removal rates increased as an increase of the dosage of m-NZVI and the temperature but decreased as an increase of pH and the initial concentration of HA. Cr (VI) adsorption kinetics followed a pseudo-first-order rate expression and the reaction rate constants ranged from 0.05 to 0.32 min-1. X-ray photoelectron spectroscope (XPS) analysis confirmed that the Fe (III)-critic acid and/or Cr (III)-HA compounds were formed on the m-NZVI surface, which could hinder the formation of Fe (III)-Cr (III) compounds. It was also shown that removing Cr (VI) by m-NZVI was a chemical controlled and irreversible process.
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Chen, Yunfang, Xiaoxin Xu, Jianzhang Fang, Guangying Zhou, Zhang Liu, Shuxing Wu, Weicheng Xu, Jinhui Chu, and Ximiao Zhu. "Synthesis of BiOI-TiO2Composite Nanoparticles by Microemulsion Method and Study on Their Photocatalytic Activities." Scientific World Journal 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/647040.
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This study was conducted to synthesize a series of nanosized BiOI-TiO2catalysts to photodegrade Bisphenol A solution. The BiOI-TiO2nanoparticles were synthesized in the reverse microemulsions, consisting of cyclohexane, Triton X-100, n-hexanol, and aqueous salt solutions. The synthesized particles were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface analyzer, Fourier transform-infrared spectroscopy (FT-IR), ultraviolet-visible light (UV-Vis) absorption spectra and transmission electron microscope (TEM). The photodegradation of Bisphenol A (BPA) in aqueous suspension under visible light irradiation was investigated to explore the feasibility of using the photocatalytic method to treat BPA wastewater. The effects of different molar ratios of BiOI to TiO2on the photocatalytic activity were discussed. The experimental results revealed that the photocatalytic effect of the BiOI-TiO2particles was superior to the commercial P25 TiO2. The BPA degradation could be approached by a pseudo-first-order rate expression. The observed reaction rate constant (kobs) was related to nanoparticles dosage and initial solution pH.
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Yang, Wei, Schalk Cloete, John Morud, and Shahriar Amini. "An Effective Reaction Rate Model for Gas-Solid Reactions with High Intra-Particle Diffusion Resistance." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 331–42. http://dx.doi.org/10.1515/ijcre-2015-0127.
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AbstractAn approximate analytical expression for estimating the effectiveness factors of non-catalytic gas-solid reactions is proposed. The new expression is derived from the analytical solution for simple first order reactions (Ishida and Wen 1968. Comparison of kinetic and diffusional models for solid-gas reactions. AIChE Journal 14, 311–317. http://dx.doi.org/10.1002/aic.690140218). The scaled Thiele modulus concept is introduced to account for the variations of the reaction rate form that differs from the first order. The validity of the new expression is demonstrated for the reactions of different orders and of different forms via comparisons against a complete particle-reactor model using the collocation method for solving heat and mass fluxes inside the particles. In addition, the proposed approach is applied to redox reactions of ferric oxide where non-isothermal condition, net consumption of gaseous reactant, and parallel reactions are encountered. The results show that the effectiveness factor method compared well with the orthogonal collocation method over a wide range of Thiele moduli, reaction orders and reaction forms. Therefore, the proposed expression can serve as a generic replacement for more complex and computationally expensive combined particle-reactor modelling which is often employed in reactor systems with significant intra-particle diffusion resistances.
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FAN, Ying-Xin, Zhen-Yu LI, Li ZHU, and Jun-Mei ZHOU. "Activation of dihydrofolate reductase following thiol modification involves a conformational change at the active site." Biochemical Journal 335, no. 3 (November 1, 1998): 643–46. http://dx.doi.org/10.1042/bj3350643.
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Compared with the activation of dihydrofolate reductase (DHFR) by protein denaturants and inorganic salts, activation of the enzyme by thiol modification is relatively slow. Thus it is an ideal system for kinetic study of the activation mechanism. We describe here a kinetic study of the activation of DHFRs from chicken liver and Chinese hamster ovary by p-hydroxymercuribenzoate (p-HMB). The conformational changes in the enzyme molecule that result from the modification were monitored by measuring fluorescence enhancement due to the binding of 2-p-toluidinylnaphthalene-6-sulphonate (TNS), and by monitoring changes in the intrinsic fluorescence of the enzyme. Both activation and the conformational change probed by TNS followed pseudo-first-order kinetics, and the rate constants obtained are in good agreement with each other. The change in intrinsic fluorescence is a biphasic process. The rate of the fast phase, which may reflect a change in the microenvironment of Trp-24 at the active site, coincides with the rate of activation and the conformational change probed by TNS. The rate of the slow phase, which reflects a global conformational change, is about one order of magnitude lower than that of activation. The results indicate that the activation of DHFR by p-HMB is due to modification-induced conformational changes at its active site, rather than the modification of the thiol group itself, which is almost complete within the dead-time of the experiment. This study provides kinetic evidence for the proposal that flexibility at the active site is essential for full expression of catalytic activity.
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Gonzo, Elio E., and Luis F. Gonzo. "Kinetics of Phenol Removal from Aqueous Solution by Adsorption onto Peanut Shell Acid-Activated Carbon." Adsorption Science & Technology 23, no. 4 (May 2005): 289–302. http://dx.doi.org/10.1260/0263617054770011.
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A pseudo-second-order rate equation describing the kinetic adsorption of phenol onto peanut shell acid-activated carbon at different initial concentrations, carbon dosages and particle sizes has been developed. The adsorption kinetics were followed on the basis of the amount of phenol adsorbed at various time intervals at 22°C. The rate constant and the equilibrium adsorption capacity were calculated. From these parameters, empirical correlations for predicting the equilibrium adsorption capacity as a function of the C0/D ratio, and for estimating the rate constant as a function of the relation D/(C0dp)0.5, were derived. This allowed a general rate expression for design purposes to be obtained which was valid for C0/D ≤ 1.5. The operation line for each case studied was constructed and the equilibrium adsorption capacity obtained. A comparison was undertaken with the experimental adsorption isotherm as previously determined. The effect of the initial phenol concentration, the carbon dose and the particle size on the initial adsorption rate was also analyzed.
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Cooper, William J., and Richard G. Zepp. "Hydrogen Peroxide Decay in Waters with Suspended Soils: Evidence for Biologically Mediated Processes." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 5 (May 1, 1990): 888–93. http://dx.doi.org/10.1139/f90-102.
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Hydrogen peroxide decay studies have been conducted in suspensions of several well-characterized soils and in natural water samples. Kinetic and product studies indicated that the decay was biologically-mediated, and could be described by pseudo first-order rate expressions. At an initial H2O2 concentration of 0.5 μM, the hydrogen peroxide half-life varied from 1 to 8 h. The decay was inhibited by thermal and chemical sterilization of the soils. Peroxidase activity was inferred in several natural water samples, where the suspended particles catalyzed the oxidation of p-anisidine by hydrogen peroxide. The mass spectrum of the major reaction product indicated that it was the dimer, possibly benzoquinone-4-methoxyanil, a product that also was observed from the horseradish peroxidase-catalyzed oxidation of p-anisidine by hydrogen peroxide.
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Ryoo, Keon Sang. "Sorption of Ni(II) and Cr(III) ions by the Chironomus yoshimatsui larvae from wastewater." JOURNAL OF ADVANCES IN CHEMISTRY 15, no. 1 (February 26, 2018): 6062–69. http://dx.doi.org/10.24297/jac.v15i1.6725.
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In this study, Chironomus yoshimatsui larvae were applied to remove Ni(II) and Cr(III) ions from wastewater. The sorption studies were carried out using laboratory-reared C. y. larvae. It was found that C. y. larvae are very susceptible to Cr(III) as compared to Ni(II). The survival capacity of C. y. larvae was sharply reduced when exposed to even low Cr(III) concentration. Sorption isotherm and kinetics of C. y. larvae for Ni(II) were determined by means of controlled experiments in a batch system. It was observed that sorpyion efficiency of Ni(II) was largely concentration dependent and more effective at lower concentration. At each equilibrium, Ni(II) was removed up to roughly 44∼80 %. Sorption data were better fitted to the Langmuir isotherm model because of its correlation coefficient R2 value greater than that of the Freundlich isotherm model. The sorption kinetics by C. y. larvae for Ni(II) was well described a pseudo-first-order rate expression. C. y. larvae have enormous potential for application in wastewater treatment technologies because they are widespread and abundant all around the world and can be easily kept in culture.
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Lichtenegger, Felix S., Frauke M. Schnorfeil, Katharina Emmerig, Julia S. Neitz, Barbara Beck, Rika Draenert, Wolfgang Hiddemann, and Marion Subklewe. "Pseudo-Exhaustion Of CD8+ T Cells in AML." Blood 122, no. 21 (November 15, 2013): 2615. http://dx.doi.org/10.1182/blood.v122.21.2615.2615.
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Abstract The prognosis of acute myeloid leukemia (AML), particularly when associated with adverse chromosomal or molecular aberrations, is poor due to a high relapse rate after induction chemotherapy. Postremission therapy for elimination of minimal residual disease remains a major challenge. Immunotherapeutic strategies such as dendritic cell (DC) vaccination aim at the stimulation of AML-specific immunity, especially of CD8+ T cells. However, the functionality of these cells in AML patients is not well described. Recently, T cell exhaustion has been suggested to contribute to immune evasion in various solid and hematological malignancies. Primarily demonstrated in chronic viral infections, exhausted T cells are characterized by an increased expression of several inhibitory molecules, reduced proliferation and an impaired capability of cytokine secretion and cytotoxicity. In order to characterize T cell exhaustion in AML at primary diagnosis and during refractory disease, we assessed the phenotype and effector function of CD8+ T cells by flow cytometry. Surface expression of the inhibitory molecules CD244 (2B4), CD160, PD-1, TIM-3 and LAG-3 was determined. T cell proliferation and production of the cytokines IFN-γ, TNF-α and IL-2 were measured in response to different stimuli. Results were compared to healthy controls (HCs), while untreated HIV-infected patients served as positive controls for an exhausted state of CD8+ T cells. To specify the effect of DCs on the state of T cell exhaustion in AML, we cocultured in vitro generated DCs with autologous T cells from primary diagnosis for four days. Compared to HCs, we detected similarly increased frequencies of CD244- and TIM-3-positive CD8+ T cells in AML and HIV patients (CD244: HCs 37±17%, AML primary diagnosis/refractory disease 72±21%/67±9%, HIV 70±7%; TIM-3: HCs 1.1±1.5%, AML primary diagnosis/refractory disease 2.9±2.2%/4.7±4.4%, HIV 2.9±2.4%; mean±SD). In refractory AML, we additionally observed an increased frequency of CD8+ T cells positive for CD160 and PD-1 (CD160: HCs 19±9%, AML refractory disease 32±8%; PD-1: HCs 21±8%, AML refractory disease 50±25%). In our functional analyses, however, T cells from AML patients and HCs were equally able to produce IFN-γ, TNF-α and IL-2 upon in vitro stimulation with a CEFT peptide pool, PMA/Ionomycin or anti-CD3/CD28. Using the CEFT peptide pool for stimulation, we even measured an increase in proliferation of T cells from AML patients compared to T cells from HCs and HIV-infected patients. The in vitro stimulation of AML cells with DCs generated from autologous monocytes resulted in a further upregulation of the molecules PD-1 and TIM-3. In summary, we found an increased overall expression of inhibitory surface molecules associated with T cell exhaustion on CD8+ T cells of AML patients at primary diagnosis and with refractory disease, which was further enhanced by in vitro stimulation with DCs. In contrast, no impairment of functionality was detected, as determined by proliferation and cytokine secretion assays. We therefore hypothesize that bulk CD8+ T cells in AML are in a status of activation, not exhaustion. Disclosures: No relevant conflicts of interest to declare.
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Pauletti, M. S., E. J. Matta, and S. Rozycki. "Kinetics of heat-induced browning in concentrated milk with sucrose as affected by pH and temperature / Cinética del pardeamiento inducido por calor en sistemas de leche concentrada con alto contenido de sacarosa. Influencia del pH y de la temperatura." Food Science and Technology International 5, no. 5 (October 1999): 407–13. http://dx.doi.org/10.1177/108201329900500506.
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A model system constituted by whole dry milk powder, sucrose, and distilled water was used to establish kinetic parameters of the heat-induced browning process (HIBP). Second-order central com posite design was chosen with pH and temperature as selected variables. Color response was the Kubelka-Munk index (K/S) calculated from reflectance colorimetric measures as a function of time using the self-backing reflectance transformation (SBRT) procedure. Results showed that HIBP pseudo- order reactions were variable between 0 and 0.6. Reaction rate coefficient (k) was strongly dependent on pH and temperature. In general, k increased as both pH and temperature increased but the influ ence of temperature was higher than that of pH. Q10 was dependent on temperature, ranging be tween 2.15 at 130-140 °C and 2.44 at 100-110 °C, whatever the pH. k values were analyzed with the Arrhenius expression. Values of Ea, calculated for different pH, were coincident (25.34 kcal/M).
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Gholamnia, Reza, Mehrnoosh Abtahi, Reza Saeedi, and Shokooh Sadat Khaloo. "Synthesis and characterization of a new magnetic adsorbent for removal of 4-nitrophenol: application of response surface methodology." Water Science and Technology 80, no. 8 (October 15, 2019): 1430–42. http://dx.doi.org/10.2166/wst.2019.390.
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Abstract Magnetic modified graphene oxide was synthesized as a new modified magnetic nano-composite (MMNC) by a simple sonochemical–hydrothermal method. The sonochemical reaction was employed to exfoliate, functionalize and decorate neomycin on graphene oxide sheets. Nickel ferromagnetic particles were synthesized by hydrothermal co-precipitation method and decorated on neomycin-modified graphene oxide. The morphology and chemical structure of MMNC were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction spectroscopy. The adsorption capability of MMNC for removal of phenolic compounds was assessed through adsorption of 4-nitrophenol (4-NP) from aqueous solution. The three-factor Box–Behnken design coupled with response surface method was applied to evaluate and optimize the important variables which affect the adsorption process. A significant quadratic model (p-value <0.05, R2(adj) = 0.9593) was derived using analysis of variance. The maximum adsorption capacity of 125.4 mg 4-NP/g MMNC at pH 6 was obtained, which was comparable in some cases and higher than most adsorbents reported in the literature. The presence of neomycin on graphene oxide sheets improved the maximum adsorption capacity of the nano-sorbent up to 28% (from 98.7 to 125.4 mg 4-NP/g adsorbent). The adsorption isotherms fitted well with the Langmuir model (Langmuir constant b = 0.064 l/mg, R2 = 0.9989) and the kinetic study showed that the nitrophenol uptake process followed the pseudo-second-order rate expression (R2 ≥ 0.9960, pseudo-second-order constant K2 ≥ 1.7 × 10−3).
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Chen, I.-Chien, Kuen-Haur Lee, Ying-Hua Hsu, Wei-Ran Wang, Chuan-Mu Chen, and Ya-Wen Cheng. "Expression Pattern and Clinicopathological Relevance of the Indoleamine 2,3-Dioxygenase 1/Tryptophan 2,3-Dioxygenase Protein in Colorectal Cancer." Disease Markers 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/8169724.
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Aims. Cancer cells use the indoleamine 2,3-dioxygenase 1 (IDO1) pathway to suppress the host’s immune response in order to facilitate survival, growth, invasion, and metastasis of malignant cells. Higher IDO1 expression was shown to be involved in colorectal cancer (CRC) progression and to be correlated with impaired clinical outcome. However, the potential correlation between the expression of IDO1 in a CRC population with a low mutation rate of theAPCgene remains unknown.Material and Methods. Tissues and blood samples were collected from 192 CRC patients. The expressions of IDO1, tryptophan 2,3-dioxygenase (TDO2), and beta-catenin proteins were analyzed by immunohistochemistry. Microsatellite instability (MSI) was determined by PCR amplification of microsatellite loci.Results. The results showed that high IDO1 or TDO2 protein expression was associated with characteristics of more aggressive phenotypes of CRC. For the first time, they also revealed a positive correlation between the abnormal expression of beta-catenin and IDO1 or TDO2 proteins in a CRC population with a low mutation rate ofAPC.Conclusion. We concluded that an IDO1-regulated molecular pathway led to abnormal expression of beta-catenin in the nucleus/cytoplasm of CRC patients with low mutation rate ofAPC, making IDO1 an interesting target for immunotherapy in CRC.
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Hannachi, Yasser. "NICKEL BIOSORPTION BY FINELY GROUND WASTE SLUDGE / NIKELIO BIOSORBAVIMAS SMULKIAI SUMALTU NUOTEKŲ DUMBLU / БИОСОРБЦИЯ НИКЕЛЯ МЕЛКО ИЗМЕЛЬЧЕННЫМ ИЛОМ СТОКОВ." Journal of Environmental Engineering and Landscape Management 19, no. 3 (October 21, 2011): 208–14. http://dx.doi.org/10.3846/16486897.2011.602556.
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In this paper, removal of Ni (II) from aqueous solution by finely ground waste sludge (FGWS) was investigated. Waste sludge samples obtained from a varnishes and lacquers industry wastewater treatment plant was dried, ground and pre-treated with 1% H2O2 to improve the biosorption capacity. Kinetics of nickel biosorption onto FGWS was investigated by using the FGWS samples with particle size of 62.2 µm. The pseudo-first and second order rate expressions were used to correlate the experimental data. The kinetic constants were determined for both models and the second order rate expression was found to be more suitable. Three different biosorption isotherms were used to correlate the equilibrium biosorption data and the isotherm constants were determined. The Langmuir isotherm was found to fit the experimental data better than the other tested isotherms. The biosorption capacity (qm) and saturation constant (K) for the Langmuir isotherm showed that finely ground waste sludge has the largest capacity and affinity for removal of Ni(II) compared to the other Activated sludges. Santrauka Nagrinėjami Ni(II) šalinimo iš vandeninių tirpalų smulkiai sumaltu nuotekų dumblu (SSND) tyrimų rezultatai. Nuotekų dumblo pavyzdžiai imti iš glazūravimo ir lakavimo pramonės nuotekų valymo įrenginių, išdžiovinti, susmulkinti ir apdoroti 1% H2O2, kad padidėtų biosorbcijos tūris. Nikelio sorbcijos SSND kinetika tirta naudojant SSND bandinius, kurių dalelių dydis 62,2 µm. Pseudo pirmojo ir antrojo laipsnio greičio išraiškos buvo taikomos eksperimentinių duomenų koreliacijai apibrėžti. Kinetinė konstanta nustatyta abiejų modelių, tačiau antrojo laipsnio greičio išraiška buvo tinkamesnė. Pagal tris skirtingas biosorbcijos izotermes nustatyta biosorbcijos pusiausvyros duomenų koreliacija, rastos izotermių konstantos. Langmiuro (Langmuir) izotermė geriau atitiko eksperimentinius duomenis nei kitos tirtosios izotermės. Pagal Langmiuro izotermę biosorbcijos geba (q m) ir prisotinimo konstanta (K) rodė, kad smulkiai sumalto nuotekų dumblo geba šalinti Ni(II) yra didžiausia, palyginti su kitos rūšies aktyvintojo dumblo. Резюме Исследуется удаление Ni(II) из водных растворов мелко измельченным илом стоков (МИИС). Образцы ила стоковбыли взяты из оборудования по очистке стоков в промышленности по глазурованию и лакованию. Затем образцы были высушены, измельчены и обработаны 1-процентным H2O2, с целью увеличить объем биосорбции. Кинетика сорбции никеля МИИС исследовалась с применением образцов МИИС, величина частиц которых составляла62,2 μм. Выражения скорости псевдопервой и псевдовторой степени использовались для определения корреляции экспериментальных данных. Кинетическая константа была установлена для обеих моделей. Однако выражение скорости второй степени оказалось более приемлемым. Три разные изотермы биосорбции применялись для определения корреляции данных по равновесию биосорбции и констант изотерм. Изотерма Langmuir лучше совпала с экспериментальными данными, чем другие испытуемые изотермы. Способность биосорбции (q m) изотермы Langmuir и константа насыщения (K) показали, что мелко измельченный ил стоков обладает наибольшей способностью удалять Ni(II) по сравнению с другими видами активированного ила.
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Zhao, Hui, Yu Tai Wang, and Xing Hai Yang. "Emotion Detection System Based on Speech and Facial Signals." Advanced Materials Research 459 (January 2012): 483–87. http://dx.doi.org/10.4028/www.scientific.net/amr.459.483.
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This paper introduces the present status of speech emotion detection. In order to improve the emotion recognition rate of single mode, the bimodal fusion method based on speech and facial expression is proposed. First, we establishes emotional database include speech and facial expression. For different emotions, calm, happy, surprise, anger, sad, we extract ten speech parameters and use the PCA method to detect the speech emotion. Then we analyze the bimodal emotion detection of fusing facial expression information. The experiment results show that the emotion recognition rate with bimodal fusion is about 6 percent points higher than the recognition rate with only speech prosodic features
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Davis, M. E., and J. B. Burkholder. "Rate coefficients for the gas-phase reaction of OH with <i>Z</i>-3-hexen-1-ol, 1-penten-3-ol, <i>E</i>-2-penten-1-ol, and <i>E</i>-2-hexen-1-ol between 243 and 404 K." Atmospheric Chemistry and Physics Discussions 11, no. 1 (January 24, 2011): 2377–405. http://dx.doi.org/10.5194/acpd-11-2377-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-3-hexen-1-ol ((Z)-CH3CH2CH=CHCH2CH2OH). (k1), 1-penten-3-ol (CH3CH2CH(OH)CH=CH2) (k2), (E)-2-penten-1-ol ((E)-CH3CH2CH=CHCH2OH) (k3), and (E)-2-hexen-1-ol ((E)-CH3CH2CH2CH=CHCH2OH) (k4), unsaturated alcohols that are emitted into the atmosphere following vegetation wounding, are reported. Rate coefficients were measured under pseudo-first-order conditions in OH over the temperature range 243–404 K at pressures between 20 and 100 Torr (He) using pulsed laser photolysis (PLP) to produce OH radicals and laser induced fluorescence (LIF) to monitor the OH temporal profile. The obtained rate coefficients were independent of pressure with negative temperature dependences that are well described by the Arrhenius expressions k1(T) = (1.3 ± 0.1) × 10−11 exp[(580 ± 10)/T]; k1(297K) = (1.06 ± 0.12) × 10−10 k2(T) = (6.8 ± 0.7) × 10−12 exp[(690 ± 20)/T]; k2(297K) = (7.12 ± 0.73) × 10−11 k3(T) = (6.8 ± 0.8) × 10−12 exp[(680 ± 20)/T]; k3(297K) = (6.76 ± 0.70) × 10−11 k4(T) = (5.4 ± 0.6) × 10−12 exp[(690 ± 20)/T]; k4(297K) = (6.15 ± 0.75) × 10−11 (in units of cm3 molecule−1 s−1). The quoted uncertainties are at the 2σ (95% confidence) level and include estimated systematic errors. The rate coefficients obtained in this study are compared with literature values where possible.
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Sobczak, Agnieszka, Monika A. Lesniewska-Kowiel, Izabela Muszalska, Artur Firlej, Judyta Cielecka-Piontek, Szymon Tomczak, Bolesław Barszcz, Irena Oszczapowicz, and Anna Jelińska. "Stability of Epidoxorubicin Hydrochloride in Aqueous Solutions: Experimental and Theoretical Studies." Journal of Chemistry 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/8107140.
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The first-order degradation kinetics of epidoxorubicin were investigated as a function of pH, temperature, and buffers concentrations. The degradation was followed by HPLC. Buffer catalysis was observed in acetate and phosphate buffers. The pH-rate profiles were obtained at 333, 343, 353, and 363 K. The pH-rate expression was kpH=k1×aH+×f1+k2×f1+k3×f2+(k4×f2+k5×f3)×aOH-, where k1, k4, and k5 are the second-order rate constants (mol−1 L s−1) for hydrogen ion activity and for hydroxyl ion activity, respectively, and k2 and k3 are the first-order constants (s−1) for spontaneous reaction under the influence of water. Epidoxorubicin demonstrates the greatest stability in the pH range 3–5. The electrostatic molecular potential orbitals HOMO-LUMO were also defined in order to determine the cause of the reactivity of particular epidoxorubicin molecule domains in solutions with various pH values.
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Wang, Qing Wei, and Zi Lu Ying. "Facial Expression Recognition Algorithm Based on Gabor Texture Features and Adaboost Feature Selection via Sparse Representation." Applied Mechanics and Materials 511-512 (February 2014): 433–36. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.433.
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This paper proposed a new facial expression recognition algorithm based on gabor texture features and Adaboost feature selection via SRC(sparse representation classification). Five scales and eight orientations of Gabor wavelet filters were used in this paper to extract gabor features. For an image of size , the number of gabor features is 163840, In order to extract the most effective features for FER(facial expression recognition), Adaboost algorithm is used for feature selection. This paper divided 7 facial expressions into two categories, where the neutral expression as the first class and the remaining six expressions as the second class. In each size and orientation 110 features are selected. At last 4400 features are selected combined SRC algorithm for FER. Test experiments were performed on Japanese female JAFFE facial expression database. Compared with the traditional expression recognition algorithms such as 2DPCA+SVM, LDA+SVM, the new algorithm achieved a better recognition rate, which shows the effectiveness of the proposed new algorithm.
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Lorenzani, Silvia. "Higher order slip according to the linearized Boltzmann equation with general boundary conditions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1944 (June 13, 2011): 2228–36. http://dx.doi.org/10.1098/rsta.2011.0059.
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In the present paper, we provide an analytical expression for the first- and second-order velocity slip coefficients by means of a variational technique that applies to the integrodifferential form of the Boltzmann equation based on the true linearized collision operator and the Cercignani–Lampis scattering kernel of the gas–surface interaction. The polynomial form of the Knudsen number obtained for the Poiseuille mass flow rate and the values of the velocity slip coefficients are analysed in the frame of potential applications of the lattice Boltzmann methods in simulations of microscale flows.
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Yin, Wan-Lee. "The Energy Release Rate in the General Delamination Problem of Anisotropic Laminates Under Thermomechanical Loads." Journal of Applied Mechanics 65, no. 1 (March 1, 1998): 85–92. http://dx.doi.org/10.1115/1.2789051.
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A simple formulation, directly in terms of the local variables of the laminated plate theory, is used to derive the general expression of the energy release rate at a boundary point of an arbitrarily shaped delamination in a multilayered anisotropic laminate under combined mechanical and temperature loads. The intact and de-bonded sublaminates are modeled using the first-order shear deformation theory. If the thermoelastic constitutive equations of the sublaminates are linear and uncoupled, then the expression of the energy release rate may be reduced to a simple form depending only on the sublaminate stiffness coefficients and the local values of the midplane strains and curvatures. The expression does not explicitly involve the temperature load, and is also independent of the strain and curvature parameters tangential to the delamination front. The corresponding expression for delamination in classical laminated plates is also given. The results are applied to the problem of a laminated strip with a fully developed edge delamination loaded under axial extension, bending, and twisting.
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EWART, TIMOTHÉE, PIERRE PERRIER, IRINA A. GRAUR, and J. GILBERT MÉOLANS. "Mass flow rate measurements in a microchannel, from hydrodynamic to near free molecular regimes." Journal of Fluid Mechanics 584 (July 25, 2007): 337–56. http://dx.doi.org/10.1017/s0022112007006374.
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Helium mass flow rates in a microchannel were measured, for a wide Knudsen-number range, in isothermal steady conditions. The flow Knudsen numbers, considered here, cover the range from continuum slip regime to the near free molecular regime. We used a single-channel system involved in an experimental platform more powerful than those previously used. The experimental errors and uncertainties were accurately investigated and estimated. In the continuum slip regime, it was found that the first-order approach is pertinent for Knudsen number between 0.03 and 0.3. Moreover, the slip coefficient was deduced by comparing the experiments with the theoretical first-order slip continuum approach. For Knudsen number between 0.03 and 0.7, a polynomial second-power form is proposed for the mass flow rate expression. Otherwise, the experimental results on the mass flow rate were compared with theoretical values calculated from kinetic approaches over the 0.03–50 Knudsen number range, and an overall agreement appears through the comparison. It was also found, when the Knudsen number increased, that the wall influence on measurement occurred first through the accommodation process in the transition regime followed by the wall influence through the aspect ratio in the free molecular regime.
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CHOI, JAE-YOUNG, TAEG-KEUN WHANGBO, YOUNG-GYU YANG, MURLIKRISHNA VISWANATHAN, and NAK-BIN KIM. "POSE-EXPRESSION NORMALIZATION FOR FACE RECOGNITION USING CONNECTED COMPONENTS ANALYSIS." International Journal of Pattern Recognition and Artificial Intelligence 20, no. 06 (September 2006): 869–81. http://dx.doi.org/10.1142/s0218001406005010.
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Accurate measurement of poses and expressions can increase the efficiency of recognition systems by avoiding the recognition of spurious faces. This paper presents a novel and robust pose-expression invariant face recognition method in order to improve the existing face recognition techniques. First, we apply the TSL color model for detecting facial region and estimate the vector X-Y-Z of face using connected components analysis. Second, the input face is mapped by a deformable 3D facial model. Third, the mapped face is transformed to the frontal face which appropriates for face recognition by the estimated pose vector and action unit of expression. Finally, the damaged regions which occur during the process of normalization are reconstructed using PCA. Several empirical tests are used to validate the application of face detection model and the method for estimating facial poses and expression. In addition, the tests suggest that recognition rate is greatly boosted through the normalization of the poses and expression.
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CAO, NHAN THI, AN HOA TON-THAT, and HYUNG IL CHOI. "FACIAL EXPRESSION RECOGNITION BASED ON LOCAL BINARY PATTERN FEATURES AND SUPPORT VECTOR MACHINE." International Journal of Pattern Recognition and Artificial Intelligence 28, no. 06 (September 2014): 1456012. http://dx.doi.org/10.1142/s0218001414560126.
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Facial expression recognition has been researched much in recent years because of their applications in intelligent communication systems. Many methods have been developed based on extracting Local Binary Pattern (LBP) features associating different classifying techniques in order to get more and more better effects of facial expression recognition. In this work, we propose a novel method for recognizing facial expressions based on Local Binary Pattern features and Support Vector Machine with two effective improvements. First is the preprocessing step and second is the method of dividing face images into nonoverlap square regions for extracting LBP features. The method was experimented on three typical kinds of database: small (213 images), medium (2040 images) and large (5130 images). Experimental results show the effectiveness of our method for obtaining remarkably better recognition rate in comparison with other methods.
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Davis, M. E., and J. B. Burkholder. "Rate coefficients for the gas-phase reaction of OH with (<i>Z</i>)-3-hexen-1-ol, 1-penten-3-ol, (<i>E</i>)-2-penten-1-ol, and (<i>E</i>)-2-hexen-1-ol between 243 and 404 K." Atmospheric Chemistry and Physics 11, no. 7 (April 8, 2011): 3347–58. http://dx.doi.org/10.5194/acp-11-3347-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of the OH radical with (Z)-3-hexen-1-ol (Z)-CH3CH2CH = CHCH2CH2OH) (k1), 1-penten-3-ol (CH3CH2CH(OH)CH = CH2) (k2), (E)-2-penten-1-ol ((E)-CH3CH2CH = CHCH2OH) (k3), and (E)-2-hexen-1-ol ((E)-CH3CH2CH2CH = CHCH2OH) (k4), unsaturated alcohols that are emitted into the atmosphere following vegetation wounding, are reported. Rate coefficients were measured under pseudo-first-order conditions in OH over the temperature range 243–404 K at pressures between 20 and 100 Torr (He) using pulsed laser photolysis (PLP) to produce OH radicals and laser induced fluorescence (LIF) to monitor the OH temporal profile. The obtained rate coefficients were independent of pressure with negative temperature dependences that are well described by the Arrhenius expressions k1(T) = (1.3 ± 0.1) × 10−11 exp[(580 ± 10)/T]; k1(297 K) = (1.06 ± 0.12) × 10−10 k2(T) = (6.8 ± 0.7) × 10−12 exp[(690 ± 20)/T]; k2(297 K) = (7.12 ± 0.73) × 10−11 k3(T) = (6.8 ± 0.8) × 10−12 exp[(680 ± 20)/T]; k3(297 K) = (6.76 ± 0.70) × 10−11 k4(T) = (5.4 − 0.6) × 10−12 exp[(690 ± 20)/T]; k4(297 K) = (6.15 ± 0.75) × 10−11 (in units of cm3 molecule−1 s−1). The quoted uncertainties are at the 2σ (95% confidence) level and include estimated systematic errors. The rate coefficients obtained in this study are compared with literature values where possible.
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Abudula, Abulizi, Winfried Rommerskirch, Ekkehard Weber, Dagmar Günther, and Bernd Wiederanders. "Splice Variants of Human Cathepsin L mRNA Show Different Expression Rates." Biological Chemistry 382, no. 11 (November 13, 2001): 1583–91. http://dx.doi.org/10.1515/bc.2001.193.
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Abstract Human cathepsin L (hCATL) mRNA occurs in vivo in at least three splice variants. They differ in the length of exon 1, which comprises 278 nucleotides (hCATLA), 188 nucleotides (hCATLA2) and 132 nucleotides (hCATLA3), respectively. We describe here the shortest variant for the first time. This form is predominant in all tissues and cells examined so far, including malignant tumors. We studied the expression rate of the three mRNA variants in order to explain why malignant kidney tumors show low cathepsin L activity despite of high mRNA levels. The variant hCATLA3 showed the highest expression rate in vitro and in vivo. Based on these results, we suggest a cisacting element on human cathepsin L mRNA which can be bound by a negative transacting regulator, thus leading to reduced expression rates.
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Ha, Vu Thi Thai, Nguyen Thi Quy Hai, and Nguyen Ngoc Long. "Effect of Heating Rate on the Responses of LiF: Mg, Cu, Na, Si Thermoluminescent Phosphor." Communications in Physics 21, no. 1 (March 31, 2011): 43. http://dx.doi.org/10.15625/0868-3166/21/1/91.
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In the current work the glow curves for LiF:Mg,Cu,Na,Si thermoluminescent material were measured and analyzed by using a function approximating to the well-known Randall-Wilkins first-order expression. The influence of different heating rates on thermoluminescent glow-peak maximum temperature, peak height and integrated area of the glow peak was investigated for LiF:Mg,Cu,Na,Si phosphor. The results show that the glow-peak temperature, peak height and glow peak area increase with increasing heating rate, while the full width at half maximum of glow peak almost keeps constant in the range of heating rates studied.
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Allen, M. A., and G. Rowlands. "Stability of obliquely propagating plane solitons of the Zakharov–Kuznetsov equation." Journal of Plasma Physics 53, no. 1 (February 1995): 63–73. http://dx.doi.org/10.1017/s002237780001802x.
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By determining to first order the growth rate of a small, long-wavelength, perturbation to a Zakharov–Kuznetsov plane soliton moving at an angle α to the magnetic field, it has been found that such solitons are unstable for α α0( ∼ 38 °). To determine the stability for angles greater than α0, one needs the growth rate to higher order. The conventional approach generates a second-order growth rate that is singular at α = α0. We rigorously obtain an expression that is bounded at this point, by developing a method in which exponentially secular terms that arise are regrouped before their subsequent elimination. We then show that these solitons are unstable for all α, although the growth rate is small for α>α and goes to zero as α→½π. The relevant linearized equation is solved numerically, and excellent agreement between analytical and numerical results is obtained.
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Lontoh, Sonny, and Jeremy D. Semrau. "Methane and Trichloroethylene Degradation byMethylosinus trichosporium OB3b Expressing Particulate Methane Monooxygenase." Applied and Environmental Microbiology 64, no. 3 (March 1, 1998): 1106–14. http://dx.doi.org/10.1128/aem.64.3.1106-1114.1998.
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ABSTRACT Whole-cell assays of methane and trichloroethylene (TCE) consumption have been performed on Methylosinus trichosporium OB3b expressing particulate methane monooxygenase (pMMO). From these assays it is apparent that varying the growth concentration of copper causes a change in the kinetics of methane and TCE degradation. For M. trichosporium OB3b, increasing the copper growth concentration from 2.5 to 20 μM caused the maximal degradation rate of methane (V max) to decrease from 300 to 82 nmol of methane/min/mg of protein. The methane concentration at half the maximal degradation rate (Ks ) also decreased from 62 to 8.3 μM. The pseudo-first-order rate constant for methane,V max/Ks , doubled from 4.9 × 10−3 to 9.9 × 10−3liters/min/mg of protein, however, as the growth concentration of copper increased from 2.5 to 20 μM. TCE degradation by M. trichosporium OB3b was also examined with varying copper and formate concentrations. M. trichosporium OB3b grown with 2.5 μM copper was unable to degrade TCE in both the absence and presence of an exogenous source of reducing equivalents in the form of formate. Cells grown with 20 μM copper, however, were able to degrade TCE regardless of whether formate was provided. Without formate theV max for TCE was 2.5 nmol/min/mg of protein, while providing formate increased the V max to 4.1 nmol/min/mg of protein. The affinity for TCE also increased with increasing copper, as seen by a change in Ks from 36 to 7.9 μM.V max/Ks for TCE degradation by pMMO also increased from 6.9 × 10−5to 5.2 × 10−4 liters/min/mg of protein with the addition of formate. From these whole-cell studies it is apparent that the amount of copper available is critical in determining the oxidation of substrates in methanotrophs that are expressing only pMMO.
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Zhao, Yingyu, Zhenbin Chen, Jie Li, Zhen Liu, Donglei Liu, and Zhizong Li. "Preparative separation and purification of flavonoids from Lamiophlomis rotata (Benth.) Kudo." Pigment & Resin Technology 46, no. 6 (November 6, 2017): 496–506. http://dx.doi.org/10.1108/prt-12-2016-0119.
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Purpose The purpose of the paper is to separate and purify flavonoids existed in Lamiophlomis rotata (Benth.) Kudo. by macroporous adsorption resin (MAR) mixed-bed technology. Design/methodology/approach The adsorption and desorption parameters were characterized by UV-VIS spectrophotometry. The optimal MAR mixed bed was screened based on the adsorption experiments; the experiment process was investigated by the order of single, two and three MAR mixed bed separately; and the adsorption performance, which was composed by the authority of 80 per cent adsorption ratios and 20 per cent desorption ratios, was adopted to screen MAR mixed bed for flavonoids. The adsorption dynamic investigated the order of reaction first, and then the adsorption mechanism was researched further. The adsorption thermodynamic investigated the adsorption isotherm first, and then the adsorption feature was analyzed. Findings This research found that MAR mixed bed of LS-840 + LSD301 with mass ratio of mLS840:mLSD301 = 3:2 was the optimized combination, and the optimal conditions of the adsorption were volume V = 50 mL, time t = 6.5 h, T = 40°C. The desorption conditions were ethanol content = 70 per cent, desorption time t = 3.0 h, T = 40°C. The adsorption dynamic experimental data fitted better to the pseudo-second-order, and the intra-particle-diffusion model was more suitable for expression of the adsorption mechanism in mesopores process, whereas the homogeneous particle-diffusion model was more suitable in microspores. The adsorption was a physical and multilayer adsorption, and the adsorption driving force was disappeared as it transferred to the fourth layer. Practical implications Find an efficient way to separate flavonoids that useful for human’s health, which can not only utilize of plant resources effectively, but also make outstanding contributions to medical industry. It has very high economic and social value. Originality/value This contribution provided a new way to separate flavonoids from Lamiophlomis rotata (Benth.) Kudo. Under the optimal conditions, the adsorption rate (F) of MAR mixed bed LS-840 + LSD301 to the flavonoids was 97.81 per cent, the desorption rate (D) was 90.02 per cent and the purity of flavonoids was dramatically increased about 2.08 fold of the crude extract from 28 to 58.4 per cent, and the recovery yield of flavonoids arrived at 91.6 per cent after a circle of adsorption/desorption operation.
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Gönenç, I. E., D. Orhon, and B. Beler Baykal. "Application of Biofilm Kinetics to Anaerobic Fixed Bed Reactors." Water Science and Technology 23, no. 7-9 (April 1, 1991): 1319–26. http://dx.doi.org/10.2166/wst.1991.0584.
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Two basic phenomena, reactor hydraulics and mass transport through biofilm coupled with kinetic expressions for substrate transformations were accounted for in order to describe the soluble COD removal mechanism in anaerobic fixed bed reactors. To provide necessary verification, experimental results from the long term operation of the pilot scale anaerobic reactor treating molasses wastewater were used. Theoretical evaluations verified by these experimental studies showed that a bulk zero-order removal rate expression modified by diffusional resistance leading to bulk half-order and first-order rates together with the particular hydraulic conditions could adequately define the overall soluble COD removal mechanism in an anaerobic fixed bed reactor. The experimental results were also used to determine the kinetic constants for practical application. In view of the complexity of the phenomena involved it is found remarkable that a simple simulation model based on biofilm kinetics is a powerful tool for design and operation of anaerobic fixed bed reactors.
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Wang, Yin, and Keming Yao. "Optimal Skip Entry Trajectory for Lunar Return Vehicle with Trim-Flaps." Mathematical Problems in Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/3498350.
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A medium lift-to-drag ratio lunar return vehicle with trim-flaps is presented in this paper. The trajectory optimization design under heat-rate constrain for skip entry lunar return vehicle is analyzed. The optimization problem with a first-order state constraint is introduced. The trajectory applying the Pontryagin maximum principle under the performance of minimum heat is optimized, and the optimal expression of lift coefficient is derived. The simulation studies show that this research method can decrease the heat-rate effectively.
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Carbone, V. "Scaling exponents of the velocity structure functions in the interplanetary medium." Annales Geophysicae 12, no. 7 (June 30, 1994): 585–90. http://dx.doi.org/10.1007/s00585-994-0585-3.
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Abstract. We analyze the scaling exponents of the velocity structure functions, obtained from the velocity fluctuations measured in the interplanetary space plasma. Using the expression for the energy transfer rate which seems the most relevant in describing the evolution of the pseudo-energy densities in the interplanetary medium, we introduce an energy cascade model derived from a simple fragmentation process, which takes into account the intermittency effect. In the absence and in the presence of the large-scale magnetic field decorrelation effect the model reduces to the fluid and the hydromagnetic p-model, respectively. We show that the scaling exponents of the q-th power of the velocity structure functions, as obtained by the model in the absence of the decorrelation effect, furnishes the best-fit to the data analyzed from the Voyager 2 velocity field measurements at 8.5 AU. Our results allow us to hypothesize a new kind of scale-similarity for magnetohydrodynamic turbulence when the decorrelation effect is at work, related to the fourth-order velocity structure function.
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Ullah, Inam, Alexis Dowhuszko, Zhong Zheng, David González González, and Jyri Hämäläinen. "End-to-End Data Rate Performance of Decode-and-Forward Relaying with Different Resource Allocation Schemes." Mobile Information Systems 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/3708142.
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This paper studies the end-to-end (e2e) data rate of dual-hop Decode-and-Forward (DF) infrastructure relaying under different resource allocation schemes. In this context, we first provide a comparative analysis of the optimal resource allocation scheme with respect to several other approaches in order to provide insights into the system behavior and show the benefits of each alternative. Then, assuming the optimal resource allocation, a closed form expression for the distribution of the mean and outage data rates is derived. It turns out that the corresponding mean e2e data rate formula attains an expression in terms of an integral that does not admit a closed form solution. Therefore, a tight lower bound formula for the mean e2e data rate is presented. Results can be used to select the most convenient resource allocation scheme and perform link dimensioning in the network planning phase, showing the explicit relationships that exist between component link bandwidths, SNR values, and mean data rate.
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Brett Borup, M., and E. Joe Middlebrooks. "Photocatalysed Oxidation of Toxic Organics." Water Science and Technology 19, no. 3-4 (March 1, 1987): 381–90. http://dx.doi.org/10.2166/wst.1987.0218.
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The feasibility of treating water contaminated by two toxic organic compounds with an ultraviolet light catalyzed oxidation process using hydrogen peroxide as an oxidant is investigated. In this process hydrogen peroxide is decomposed by ultraviolet radiation producing hydroxyl radicals. The hydroxyl radicals will then oxidize organic compounds via a complex chain of radical reactions. Tests showed that this photooxidation process could successfully remove isophorone and dimethyl phthalate from contaminated waters. A reaction rate expression which adequately describes the process was developed. The reaction rate was found to be first order with respect to hydrogen peroxide concentration, zero order with respect to organic concentration and a function of ultraviolet radiation intensity. The reaction did not exhibit autocatalytic characteristics.
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Pettygrove, Dennis R., and Denny V. Naylor. "Metribuzin Degradation Kinetics in Organically Amended Soil." Weed Science 33, no. 2 (March 1985): 267–70. http://dx.doi.org/10.1017/s0043174500082230.
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The rates of degradation of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] were determined in an untreated Portneuf silt loam, in soil with added organic amendments, and in soil previously treated with metribuzin. While first-order rate kinetics generally described the degradation of the metribuzin in the soil, a quadratic expression was superior. Organic amendments were found to inhibit or accelerate the rate of breakdown of metribuzin depending upon the kind of amendment. Neither a lag phase nor an enrichment was observed from prior treatment with metribuzin.
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ZHAN, YONGZHAO, JINGFU YE, DEJIAO NIU, and PENG CAO. "FACIAL EXPRESSION RECOGNITION BASED ON GABOR WAVELET TRANSFORMATION AND ELASTIC TEMPLATES MATCHING." International Journal of Image and Graphics 06, no. 01 (January 2006): 125–38. http://dx.doi.org/10.1142/s0219467806002112.
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Facial expression recognition technology plays an important role in research areas such as psychological studies, image understanding and virtual reality etc. In order to achieve subject-independent facial expression recognition and obtain robustness against illumination variety and image deformation, facial expression recognition methods based on Gabor wavelet transformation and elastic templates matching are presented in this paper. First given a still image containing facial expression information, preprocessors are executed which include gray and scale normalization. Secondly, Gabor wavelet filters are adopted to extract expression features. Then the elastic graph for expression features is constructed. Finally, elastic templates matching algorithm and K-nearest neighbors classifier are used to recognize facial expression. Experiments show that expression features can be extracted effectively by Gabor wavelet transformation, which is insensitive to illumination variety and individual difference, and high recognition rate can be obtained using elastic templates matching algorithm, which is subject-independent.
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Chen, G. H., H. Ozaki, and Y. Terashima. "Endogenous Denitrification in Biofilm." Water Science and Technology 26, no. 3-4 (August 1, 1992): 523–34. http://dx.doi.org/10.2166/wst.1992.0432.
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The model on endogenous denitrification in a biofilm, previously presented by the authors, was verified well with bench scale experiments. Production of the secondary substrate due to lysis of microorganisms, which is necessary for the progress of endogenous denitrification, was experimentally proved. In order to investigate metabolic characteristics of the substrate, molecular weight distributions of the substrate on CODcr or carbohydrate bases were measured. The percentage of the secondary substrate with molecular weight less than 10,000, was more than 50% on both bases. The experimental results demonstrated that the production rate of the substrate can be expressed by the first order type expression with respect to the concentration of biomass. The specific constants for microorganisms lysis and maximum endogenous denitrification rate were determined (0.45 day−1 and 0.141 day−1, respectively).
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Almasri, Amin H., and George Z. Voyiadjis. "Effect of Strain Rate on the Dynamic Hardness in Metals." Journal of Engineering Materials and Technology 129, no. 4 (April 9, 2007): 505–12. http://dx.doi.org/10.1115/1.2744430.
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Traditionally, the hardness of materials is determined from indentation tests at low loading rates (static). However, considerably less work has been conducted in studying the dynamic hardness of materials using relatively high loading rates. In the present work, two models are used to predict strain rate dependency in hardness. The first model is a power law expression that is based on the dependence of the yield stress on the strain rate. This model is relatively simple in implementation, and it is quite easy to determine its parameters from simple uniaxial experiments. The second model is a micromechanical based model using Taylor’s hardening law. It utilizes the behavior of dislocation densities at high strain rates in metals in order to relate dynamic hardness to strain rates. The latter model also accounts for any changes in temperature that could exist. A finite element is also run and compared with the two models proposed in this work. Results from both models are compared with available experimental results for oxygen-free high-conductivity copper and 1018 cold rolled steel, and both models show reasonably good agreement with the experimental results.
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Ezzati, Rohollah. "Derivation of Pseudo-First-Order, Pseudo-Second-Order and Modified Pseudo-First-Order rate equations from Langmuir and Freundlich isotherms for adsorption." Chemical Engineering Journal 392 (July 2020): 123705. http://dx.doi.org/10.1016/j.cej.2019.123705.
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Chargui, H., W. Hajjaji, J. Wouters, J. Yans, and F. Jamoussi. "Direct Orange 34 dye fixation by modified kaolin." Clay Minerals 53, no. 2 (June 2018): 271–87. http://dx.doi.org/10.1180/clm.2018.18.
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ABSTRACTThe present study investigated the adsorption behaviour of Direct Orange 34, a highly toxic dye used in textile industries in Tunisia, on modified kaolinite-rich clays. A kaolin from the Sidi Bader (SDB) area was activated with hydrochloric acid to create the activated clay referred to hearafter as SDBa, or treated with FeSO4•7H2O to obtain its Fe-saturated form, Fe-SDB. The adsorbents were characterized by X-ray diffraction, X-ray fluorescence, transmission electron microscopy, BET surface area and zeta-potential measurements. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The estimated adsorption capacities (qm) for the dye were improved in the Fe-loaded samples. The good fit (R2 = 0.99) with a pseudo-second order expression suggests that the adsorption process could be effective following a chemisorption mechanism. At acidic pH, the optimum dye-retention rate was achieved for SDB (83%) after 60 min. The uptake decreased at neutral pH and increased again in alkaline media. This behaviour might be explained by the formation of covalent bonds between the OH radicals on the external surface and the negatively charged dye molecules. On the other hand, Fe impregnation increased the zeta potential of kaolinite, leading to a greater adsorption capacity compared to its natural and acid-activated counterparts. In addition, the adsorption rate increased when increasing the suspension temperature from 283 to 313 K. The modified kaolinite-rich materials showed satisfactory affinity for adsorbing this reactive dye.
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Zhai-min, Wang, Pi Pi-hui, Wen Xiu-fang, Cheng Jiang, and Yang Zhuo-ru. "Analysis of Most Probable Mechanism Functions and Thermal Degradation Kinetics of N-Phenylmaleimide-Styrene-Maleic Copolymers." Polymers and Polymer Composites 15, no. 5 (July 2007): 409–14. http://dx.doi.org/10.1177/096739110701500509.
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The thermal degradation kinetics of N-phenylmaleimide-styrene-maleic (NSMA) anhydride copolymers was analysed by a non-isothermal kinetic method. Kinetic parameters were obtained using integral and differential methods, and the most probable mechanism functions and kinetic compensation effects were discussed. The activation energy E for the thermal degradation of NSMA was 211.34kJ/mol according to the Flynn-Wall-Ozawa method and the thermal degradation was a first-order chemical reaction. A recommended rate expression for the thermal degradation reaction of NSMA was [Formula: see text] (where α is the conversion, t is time, R is the gas constant, T is the temperature and A is the pre-exponential factor), and the mathematical expressions of compensation effects for the integral and differential methods were lnA=-1.8037+0.1749E and lnA=-2.1974+0.1741E respectively.
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Cai, Yiqing, Xiangxiang Zhou, Juan Yang, Jiarui Liu, Yi Zhao, Shunfeng Hu, Shuai Ren, and Xin Wang. "Single-Cell Transcriptome Reveals the Role of Sting Pathway in Acute B Lymphoblastic Leukemia Bone Marrow Cells." Blood 136, Supplement 1 (November 5, 2020): 47–48. http://dx.doi.org/10.1182/blood-2020-139028.
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Introduction Cancer immunotherapy and targeted therapy have yielded impressive clinical efficacy in acute B lymphoblastic leukemia (B-ALL). Despite the initial high complete remission (CR) rate following first-line therapy, treatment refractoriness and disease relapse remain are correlated with dismal survival. By the time the malignant cells generate, they are accompanied by a rich network of stromal cells and cytokines in bone marrow (BM). This tumor microenvironment (TME) represents an important feature of the biology of B-ALL but also shapes the clinical behavior of the disease. It remains to be confirmed whether the cellular composition and transcriptional heterogeneity impacts the clinical effects of B-ALL. Herein, we analyzed the immune cell infiltration features and related marker genes for B-ALL based on single cell RNA sequencing (scRNA-seq) data, which would be of significance for the development of novel immunotherapies. Methods ScRNA-seq data of 11373 BM cells from 3 B-ALL patients were obtained from the Gene Expression Omnibus (GEO, GSE153358). After quality control and data normalization, cell filtration and marker genes extraction were performed by the Seurat package. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) were then applied to cluster cells, following with cell types' definition and gene expression profiles in total subsets. Cell clustering was demonstrated using t-SNE-1 and t-SNE-2. In order to determine the cellular characteristics of TME cells mainly mediated by STING pathway, dendritic cell (DC) and B cell were extracted and further plotted gene expression including immunosuppressive molecules and STING pathway, respectively. The pseudo-time analysis was finally performed by Monocle package to display B cell development trajectory and gene expressions over time. Results 9 cell subsets in B-ALL BM, including naïve and memory CD4+ T cell, CD14+ monocyte, B cell, CD8+ T cell, FCGRA3+monocyte, nature killer (NK) cell, DC, and platelet, were identified based on t-SNE analysis (Fig.1A). Top 10 marker genes in each cell cluster were presented in heat map (Fig.1B). Through analyzing differentially expressed genes, we found that BM B cells hardly expressed PD-L1 (CD274), but partially carried TMEM173 (STING), NFKB1 (NF-κB) and GSDMD. In addition, immune cells in BM TME broadly distributed and highly expressed STING and NF-κB, indicating the potential response to type I innate immune response and higher sensitivity to STING agonists than PD-1 antibody (Fig.2A and B). Previous studies had revealed that STING pathway participated in the activation of DC following with production of type I IFNs. We further isolated DC from 9 subsets and profiled the gene expression features. T-SNE analysis revealed 3 subtypes of DC in BM, marker genes comparison further identified as monocyte derived DC, CD1C-CD14-DC and myeloid conventional DC. Cyclic GMP-AMP synthase (cGAS), STING and NF-κB were highly expressed in each type in compared with PDCD1 (PD-1) and highest existed on myeloid conventional DC (Fig.3). We then explored B cell subsets to determine whether STING pathway could induce cell pyroptosis in BM B cells. Different subgroup of B cells shared similar marker genes, companying with higher expression of NF-κB and GDSMD (Fig.4). Furthermore, pseudo-time analysis plotted the development trajectory of malignant B cells. The results showed that GSDMD gradually increased along with cell development, suggesting that STING agonist would be sensitive to mature B cells (Fig.5). Subsets analysis shown that anti-tumor immune response of DC and pyroptosis of B cell might be triggered through STING pathway activation. Conclusion Our study profiled for the first time the expression of STING pathway in BM DC and B cell from B-ALL patients based on single-cell transcriptome. Combination of STING agonist and conventional immunotherapy had been shown prospects in antitumor therapy. STING agonist is expected to be an adjuvant drug for B-ALL immunotherapies in the future. Keywords: Single-cell RNA sequencing; acute B lymphoblastic leukemia; STING; PD-1; immunotherapy. Disclosures No relevant conflicts of interest to declare.
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Gao, Huajian, and James R. Rice. "Shear Stress Intensity Factors for a Planar Crack With Slightly Curved Front." Journal of Applied Mechanics 53, no. 4 (December 1, 1986): 774–78. http://dx.doi.org/10.1115/1.3171857.
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Recent work (Rice, 1985a) has presented the calculations of the first order variation in an elastic displacement field associated with arbitrary incremental planar advance of the location of the front of a half-plane crack in a loaded elastic full space. That work also indicated the relation of such calculations to a three-dimensional weight function theory for crack analysis and derived an expression for the distribution of the tensile mode stress intensity factor along a slightly curved crack front, to first order accuracy in the deviation of the crack front location from a reference straight line. Here we extend the results on stress intensity factors to the shear modes, solving to similar first order accuracy for the in-plane (Mode 2) and antiplane (Mode 3) shear stress intensity factors along a slightly curved crack front. Implications of results for the configurational stability of a straight crack front are discussed. It is also shown that the concept of line tension, while qualitatively useful in characterizing the crack extension force (energy release rate) distribution exerted on a tough heterogeneity along a fracture path as the crack front begins to curve around it, does not agree with the exact first order effect that is derived here.