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Kinetic Study on CO_2 Reforming of Methane

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Chinese Journal of Chemical Engineering 2001年第2期9卷 190-195页

作者： C.E.Quincoces M.G.González centro de investigacion y desarrollo en Procesos Cataliticos (CINdeCA) 阿根廷

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.

关键词： CH4 reforming Ni catalysts syngas

Contribution of altered signal transduction associated to glutamate receptors in brain to the neurological alterations of hepatic encephalopathy

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World Journal of Gastroenterology 2006年第48期12卷 7737-7743页

作者： Vicente Felipo Laboratory of Neurobiology Centro de Investigacion Principe Felipe Valencia Spain

Patients with liver disease may present hepatic enceph- alopathy (HE), a complex neuropsychiatric syndrome covering a wide range of neurological alterations, including cognitive and motor disturbances. HE reduces the quality of life of the patients and is associated with poor prognosis. In the worse cases HE may lead to coma or death. The mechanisms leading to HE which are not well known are being studied using animal models. The neurological alterations in HE are a consequence of impaired cerebral function mainly due to alterations in neurotransmission. We review here some studies indicating that alterations in neurotransmission associated to different types of glutamate receptors are responsible for some of the cognitive and motor alterations present in HE. These studies show that the function of the signal transduction pathway glutamate-nitric oxide-cGMP associated to the NMDA type of glutamate receptors is impaired in brain in vivo in HE animal models as well as in brain of patients died of HE. Activation of NMDA receptors in brain activates this pathway and increases cGMP. In animal models of HE this increase in cGMP induced by activation of NMDA receptors is reduced, which is responsible for the impairment in learning ability in these animal models. Increasing cGMP by pharmacological means restores learning ability in rats with HE and may be a new therapeutic approach to improve cognitive function in patients with HE. However, it is necessary to previously assess the possible secondary *** with HE may present psychomotor slowing, hypokinesia and bradykinesia. Animal models of HE also show hypolocomotion. It has been shown in rats with HE that hypolocomotion is due to excessive activation of metabotropic glutamate receptors (mGluRs) in substantia nigra pars reticulata. Blocking mGluR1 in this brain area normalizes motor activity in the rats, suggesting that a similar treatment for patients with HE could be useful to treat psychomotor slowing and hy

关键词： Hepatic encephalopathy Glutamate receptors Neurological alterations Cognitive function Motor func-tion NMDA receptors Metabotropic glutamate receptors Nitric oxide cGMP

TWO NOVEL GRADIENT METHODS WITH OPTIMAL STEP SIZES

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Journal of Computational Mathematics 2021年第3期39卷 375-391页

作者： Harry Oviedo Oscar Dalmau Rafael Herrera centro de investigacion en Matematicas CIMAT A.C.GuanajuatoGto.Mexico

In this work we introduce two new Barzilai and Borwein-like steps sizes for the classical gradient method for strictly convex quadratic optimization *** proposed step sizes employ second-order information in order to obtain faster gradient-type *** step sizes are derived from two unconstrained optimization models that involve approximate information of the Hessian of the objective function.A convergence analysis of the proposed algorithm is *** numerical experiments are performed in order to compare the efficiency and effectiveness of the proposed methods with similar methods in the ***,it is observed that our proposals accelerate the gradient method at nearly no extra computational cost,which makes our proposal a good alternative to solve large-scale problems.

关键词： Gradient methods Convex quadratic optimization Hessian spectral properties Steplength selection

Temporal stability and directional change in a color cline of a marine snail from NW Spain

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Current Zoology 2024年第2期70卷 163-173页

作者： Juan Gefaell Ramon Vigo A.Honorato Gonzalez-Vazquez Juan Galindo Emilio Rolan-Alvarez centro de investigacion marina Universidade de VigoDepartamento de BioquimicaGenetica e Inmunologia36310 VigoSpain

The evolution and maintenance of color clines is a classic topic of research in evolutionary ***,studies analyzing the temporal dynamics of such clines are much less frequent,due to the difficulty of obtaining reliable data about past color distributions along environmen-tal *** this article,we describe a case of decades-long temporal stability and directional change in a color cline of the marine snail Littorina saxatilis along the coastal inlet of the Ria de Vigo(NW Spain).*** from this area shows a clear color cline with 3 distinct areas from the innermost to the more wave-exposed localities of the Ria:the inner,protected localities show an abundance of fawn-like individuals;the intermediate localities show a high diversity of colors;and the outer,wave-exposed localities show populations with a high frequency of a black and lineated *** compare data from the 1970s and 2022 in the same localities,showing that the cline has kept relatively stable for at least over half a century,except for some directional change and local variability in the frequency of certain *** regression analyses and biodiversity measures are presented to provide clues into the selective pressures that might be involved in the maintenance of this color *** research avenues to properly test the explanatory power of these selective agents as well as the possible origins of the cline are discussed.

关键词： clinal variation color polymorphism ecological gradient Littorina saxatilis natural selection wave exposure.

Bean yellow disorder virus： Parameters of transmission by Bemisia tabaci and host plant range

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Insect Science 2011年第1期18卷 50-56页

作者： German Martin Isabel maria Cuadrado Dirk Janssen Instituto Andaluz de investigacion y Formacion Agraria y Pesquera Centro La Mojonera Almeria Spain

Bean yellow disorder virus （BnYDV） was recently identified as the first crinivirus （family Closteroviridae） that infects members of the family Leguminosae. It was first observed during the autumn of 2003, causing heavy losses in French bean （Phaseolus vulgaris L.） grown commercially in Spain. The virus is transmitted by the sweetpotato whitefly, Bemisia tabaci （Hemiptera： Aleyrodidae） Q-biotype, and disease symptoms resemble nutritional disorders consisting of interveinal mottling and yellowing in leaves, combined with stiffness or brittleness, and are typically produced on the middle to lower parts of the plant. Transmission experiments showed that 50% and 100% of B. tabaci adults acquired the virus after a feeding period of 3 and 7 h, respectively. Viruliferous whiteflies infected 66% and 100% ofP. vulgaris plants after a feeding period of 12 and 24 h, respectively. The transmission efficiency of single whiteflies was 37% and persistence of BnYDV in the vector lasted up to 2 weeks with a half-life of 9 days. BnYDV was transmitted to P. vulgaris, Pisum sativum L., Lens culinaris Medik., and Vicia faba L., but not to Vigna unguiculata L., Glycine max （L.） Merr., Cicer arietum L., and to crop species belonging to families of the Solanaceae and Cucurbitaceae. No virus was detected in field samples collected from 30 different species from Boraginaceae, Asteraceae, Geraniaceae, Lamiaceae, Leguminosae, Malvaceae, Scrophulariaceae, Thymelaeaceae and Verbenaceae. The restricted host range and efficient management of crops regarding whitefly infestation may be key elements in the control of BnYDV.

关键词： bean Closteroviridae Crinivirus disease vector whiteflies

Distribution Function of the Blow up Time of the Solution of an Anticipating Random Fatigue Equation

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Acta Mathematica Sinica,English Series 2021年第4期37卷 551-564页

作者： Liliana PERALTA centro de investigacion en Matematicas UAEHCarretera Pachuca-Tulancingo km 4.5 PachucaHidalgo 42184Mexico

In this paper,we study the distribution function of the time of explosion of a stochastic differential equation modeling the length of the dominant crack due to *** main novelty is that initial condition is regarded as an anticipating random variable and the stochastic integral is in the forward *** suitable conditions,we use the substitution formula from Russo and Vallois to find the local solution of this ***,we find the law of blow up time by proving some results on barrier crossing probabilities of Brownian bridge.

关键词： Stochastic differential equations random fatigue explosion time forward integral Brownian bridge

Laser induced photo-detachment of O2 in DC discharge

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Plasma Science and Technology 2018年第7期20卷 98-105页

作者： j r legorreta j l patiNo f b yousif centro de investigacion en Ciencias Universidad Autonoma del Estado de Morelos.Av.UniversidadNo.1001 Col.Chamilpa Cuemavaca MorelosMexico

determination of the negative ion number density of O2 and O in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo- detachment technique. The temporal evolution of the extra electrons resulting from the photo- detachment of O2- and O- were used to evaluate the negative ion number density. The ratio of O2 number density to O varied from 0.03 to 0.22. Number density of both O~ and O increased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function （EEDF） using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the 02（al△g） metastable state is discussed.

关键词： electronegative plasma electron temperature Langmuir probe negative ion number density

Tetrapartite entanglement measures of generalized GHZ state in the noninertial frames

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Chinese Physics B 2022年第3期31卷 170-176页

作者： Qian Dong R.Santana Carrillo Guo-Hua Sun Shi-Hai Dong centro de investigacion en Computacion Instituto Politecnico NacionalUPALMCDMX 07738Mexico Catedratica CONACyT Centro de Investigacion en ComputacionInstituto Politenico NacionalUPALMCDMX 07738Mexico Research Center for Quantum Physics Huzhou UniversityHuzhou 313000China Laboraorio de Informacion Cuantica CIDETECInstituto Poitenico NacionalUPALMCDMX 07700Mexico

Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acceleration is considered for simplicity. In terms of explicit negativity calculated, we notice that the difference between the algebraic average π_(4) and geometric average Π_(4) is very small with the increasing accelerated observers and they are totally equal when all four qubits are accelerated simultaneously. The entanglement properties are discussed from one accelerated observer to all four accelerated observers. It is shown that the entanglement still exists even if the acceleration parameter r goes to infinity. It is interesting to discover that all 1-1 tangles are equal to zero, but 1-3 and 2-2 tangles always decrease when the acceleration parameter γ increases. We also study the von Neumann entropy and find that it increases with the number of the accelerated observers. In addition, we find that the von Neumann entropy S_(ABCDI), S_(ABCIDI), S_(ABICIDI) and S_(AIBICIDI) always decrease with the controllable angle θ, while the entropies S_(3-3 non), S_(3-2 non), S_(3-1 non) and S_(3-0 non) first increase with the angle θ and then decrease with it.

关键词： tetrapartite generalized GHZ state entanglement measures dirac field noninertial frames

development of cork oak (Quercus suber L.) seedlings in response to tree shelters and mulching in northwestern Tunisia

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Journal of Forestry Research 2013年第2期24卷 193-204页

作者： Taher Mechergui Marta Pardos Naceur Boussaidi Brahim Hasnaoui Douglass F. Jacobs Faculté des Sciences de Bizerte (FSB) Instituto Nacional de investigacion y Tecnologia Agraria y Alimentaria (INIA). centro de investigacion Forestal. Ctra. de La Coruňa Institut Sylvo-Pastoral de Tabarka department of Forestry and Natural Resources Purdue University

The need for reforestation in cork oak （Quercus suber L.） areas is challenged by difficulties. Principal among these is herbivory of young plants, vegetative competition, and slow growth rates of cork oak seedlings. We evaluated the early development of cork oak seedlings treated using tree shelters and mulching in northwestern Tunisia. We tested three tree shelter treatments （non-vented, vented, and control） to shield seedlings from animal damage and five mulch types to control competing vegetation （Italian Stone Pine, Lentisk, combination of Italian Stone Pine and Lentisk （organic mulches）, gravel （inorganic mulch） and no mulch）. At the end of the two-year experiment, sheltered seedlings were 89-99% taller than unshelteredseedlings and had higher numbers and lengths of shoot growth flushes. In contrast, both stem diameter growth and dry weight biomass （from samples extracted after two years） were significantly reduced inside tree shelters. Root-to-shoot ratio was not significantly different in sheltered vs. unsheltered seedlings, suggesting that tree shelters do not adversely affect this parameter. Mulching alone did not favour growth, but could be beneficial when combined with tree shelters. The combination of vented tree shelters and gravel mulch was the most effective treatment for promoting diameter, height and stem volume growth.

关键词： Quercus suber L. afforestation tree shelter mulching seedling growth polycyclism