Modelling of impregnation of γ-alumina with cobalt and molybdenum salts. Co(NO3)2-(NH4)2MoO4-γ-alumina (chloride type) system

1987 ◽  
Vol 52 (3) ◽  
pp. 672-677 ◽  
Author(s):  
Jiří Hanika ◽  
Vladimír Janoušek ◽  
Karel Sporka
Keyword(s):  
Type System ◽  
Atomic Ratio ◽  
Cobalt Nitrate ◽  
Ammonium Molybdate ◽  
Active Components ◽  
Two Component ◽  
Support Particle ◽  
Aluminium Trichloride ◽  
Crude Oil Fractions ◽  
Kinetics Of

The kinetics of one-component and two-component impregnation of γ-alumina (prepared from aluminium trichloride) with aqueous solutions of cobalt nitrate and ammonium molybdate were studied and treated in terms of a mathematical model accounting for the simultaneous diffusion and adsorption of the active components. The time-dependent radial concentration profiles of the components across the cylindrical support particle were obtained. The profiles of the cobalt-to-molybdenum atomic ratio were derived from the results. The conclusions are applicable to the development of procedures for the preparation of hydrodesulphuration catalysts for the working of crude oil fractions.

Modelling of impregnation of γ-alumina with cobalt and molybdenum salts. CoCl2-(NH4)2MoO4-γ-Al2O3 (aluminate type) system

1987 ◽  
Vol 52 (3) ◽  
pp. 663-671 ◽  
Author(s):  
Jiří Hanika ◽  
Vladimír Janoušek ◽  
Karel Sporka
Keyword(s):  
Effective Diffusion ◽  
Type System ◽  
Catalyst Particle ◽  
Ammonium Molybdate ◽  
Active Components ◽  
Model Set ◽  
Cobalt Dichloride ◽  
Set Up ◽  
Electron Microanalysis ◽  
Kinetics Of

Adsorption data for the impregnation of alumina with an aqueous solution of cobalt dichloride and ammonium molybdate were treated in terms of the Langmuir adsorption isotherm and compared with a mathematical model set up to describe the kinetics of simultaneous impregnation of a support by two components. The effective diffusion coefficients of the two components at 25 °C in a cylindrical particle of alumina were obtained. The validity of the model used was verified qualitatively by comparing the numerical results with the experimental time dependent concentration profiles of the active components in a catalyst particle, measured by electron microanalysis technique.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

Hollow structure engineering of FeCo alloy nanoparticles electrospun in nitrogen-doped carbon enables high performance flexible all-solid-state zinc–air batteries

2020 ◽  
Vol 4 (4) ◽  
pp. 1747-1753 ◽  
Author(s):  
Yuanyuan Ma ◽  
Wenjie Zang ◽  
Afriyanti Sumboja ◽  
Lu Mao ◽  
Ximeng Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Hollow Structure ◽  
Active Surface ◽  
Oxygen Electrode ◽  
Active Surface Area ◽  
Active Components ◽  
Nitrogen Doped Carbon ◽  
Structure Engineering ◽  
Kinetics Of

Hollow structuring of active components is an effective strategy to improve the kinetics of oxygen electrode catalysts, arising from the increased the active surface area, the defects on the exposed surface, and the accessible active sites.

scholarly journals Activation of Bacterial Histidine Kinases: Insights into the Kinetics of the cis Autophosphorylation Mechanism

mSphere ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Gaurav D. Sankhe ◽  
Narendra M. Dixit ◽  
Deepak K. Saini
Keyword(s):  
Mathematical Model ◽  
Theoretical Approach ◽  
Reaction Rates ◽  
Antibacterial Drug ◽  
Histidine Kinases ◽  
Content Type ◽  
Two Component ◽  
Kinetics Of ◽  
Best Fit ◽  
Step Mechanism

ABSTRACT Two-component signaling systems (TCSs) are central to bacterial adaptation. However, the mechanisms underlying the reactions involving TCS proteins and their reaction rates are largely undetermined. Here, we employed a combined experimental and theoretical approach to elucidate the kinetics of autophosphorylation of three histidine kinases (HKs) of Mycobacterium tuberculosis , viz. , MtrB, PrrB, and PhoR, all known to play a role in regulating its virulence. Using wild-type and mutant proteins, we performed dimerization assays, thermophoretic-affinity measurements, and competition-based phosphorylation assays to establish that for HK, MtrB autophosphorylation occurs in cis , similar to what has been proposed for the PhoR and PrrB HKs. Next, to determine the kinetics of cis autophosphorylation, we used a quantitative high-throughput assay and identified a two-step mechanism of HK activation, involving (i) the reversible association of HK with ATP, followed by (ii) its phosphorylation. We developed a mathematical model based on this two-step cis mechanism that captured the experimental data. Best-fit parameter values yielded estimates of the extent of HK-ATP association and the rates of HK autophosphorylation, allowing quantification of the propensity of HK autophosphorylation. Our combined experimental and theoretical approach presents a facile, scalable tool to quantify reactions involving bacterial TCS proteins, useful in antibacterial drug development strategies. IMPORTANCE Two-component systems consisting of an input-sensing histidine kinase (HK) and an output-generating response regulator (RR) are one of the key apparatuses utilized by bacteria for adapting to the extracellular milieu. HK autophosphorylation is shown to occur primarily in trans (intermolecular) and more recently shown to occur in cis (intramolecular). Although the catalysis of HK activation remains universal, the reaction scheme for evaluation of the kinetic parameter differs between these designs and cis mode largely remains unexplored. We combined experimental and theoretical approach to unravel two-step mechanism of activation of three cis mode HKs of M. tuberculosis . The new mathematical model yields best-fit parameters to estimate the rates of HK-ATP association and HK autophosphorylation.

Studies of human zinc kinetics using the stable isotope 70Zn

1993 ◽  
Vol 84 (1) ◽  
pp. 113-117 ◽  
Author(s):  
N. M. Lowe ◽  
A. Green ◽  
J. M. Rhodes ◽  
M. Lombard ◽  
R. Jalan ◽  
...  
Keyword(s):  
Liver Disease ◽  
Alcoholic Liver Disease ◽  
Turnover Rate ◽  
Kinetic Studies ◽  
Normal Subjects ◽  
Short Term ◽  
Control Subjects ◽  
Two Component ◽  
Kinetics Of ◽  
Fractional Turnover

1. The short-term (120 min) kinetics of Zn turnover has been studied in control subjects and patients with alcoholic liver disease after intravenous injection of 0.5 mg of 96.5% enriched 70ZnCl2. 2. The 70Zn enrichment of plasma was found closely to obey two-compartment kinetics and the derived two-component decay equation has been used to calculate the size and turnover of the initial two rapidly exchanging pools of body Zn. 3. In normal subjects isotopic Zn appears initially to equilibrate with the whole of the plasma Zn which comprises the first metabolic compartment, pool a. This has a size of 0.72 ± 0.1 μmol/kg. 70Zn equilibration then occurs with a second compartment, pool b, consistent with a rapidly exchanging liver Zn pool of size 3.60 ± 0.93 μmol/kg. The fractional turnover rate of pool b was found to be fivefold slower than that of pool a. 4. In the alcoholic group an expansion of pool a was observed (1.63 ± 0.39 μmol/kg), but the size of the second pool was not significantly different from that of control subjects (5.55 ± 1.0 μmol/kg), although its fractional turnover was significantly increased (Kab: control subjects, 0.018 ± 0.002 min−1, alcoholic patients, 0.031 ± 0.006 min−1). 5. These data therefore demonstrate that kinetic studies using stable isotopes of Zn can provide novel information on exchangeable Zn pools in man, but provide no support for the possibility of an underlying Zn depletion in patients with alcoholic liver disease.

scholarly journals Structure, dynamics and kinetics of two-component Lantibiotic Lichenicidin

PLoS ONE ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. e0179962 ◽  
Author(s):  
Alejandra de Miguel ◽  
Rafael Tapia-Rojo ◽  
Tillmann Utesch ◽  
Maria Andrea Mroginski
Keyword(s):  
Structure Dynamics ◽  
Two Component ◽  
Kinetics Of

scholarly journals Corrosion-mechanical behavior of gas main steel in saline soils

2019 ◽  
Vol 63 (3) ◽  
pp. 105-112
Author(s):  
L. Poberezhny ◽  
A. Stanetsky ◽  
G. Grytsuliak ◽  
L. Poberezhna ◽  
M. Kosmii ◽  
...  
Keyword(s):  
Residual Life ◽  
Pipeline Steel ◽  
Mechanical Tests ◽  
Chloride Ions ◽  
Operating Costs ◽  
Saline Soils ◽  
Active Components ◽  
Gas Main ◽  
The Impact ◽  
Kinetics Of

Abstract The study of the deformation behavior of the pipeline material in conditions of loads and influences simulating the operation allows better estimation of the residual life of the pipelines and more accurate forecasting of the operating costs. The kinetics of deformation in 6 model environments simulating soil electrolytes was studied. Corrosion-mechanical tests were performed and the impact of the soil electrolyte chemical composition and the applied mechanical stresses on the corrosion behavior of the pipeline steel was studied. Significant increase in the corrosion activity of the soil electrolyte due to the synergistic effect of the corrosion-active components was found in the specified ratios of the ionic molar concentrations of sulphate and chloride ions (0.05 M: 0.1 M).

Development of Cobalt-Molybdenum Hydrodesulfurization Catalysts

1992 ◽  
Vol 57 (12) ◽  
pp. 2501-2508 ◽  
Author(s):  
Karel Sporka ◽  
Jiří Hanika
Keyword(s):  
Aqueous Solutions ◽  
Aromatic Compounds ◽  
Laboratory Scale ◽  
Gas Oil ◽  
Active Components ◽  
Hydrodesulfurization Catalysts ◽  
The Individual ◽  
Kinetics Of

The Co-Mo catalysts have been prepared on laboratory scale by controlled impregnation of extruded γ-alumina with aqueous solutions of suitable active components, and their activity has been tested in the hydrodesulfurization and hydrogenation of aromatic compounds in gas oil. The kinetics of impregnation of the carrier, the effect of its nature, the order of impregnation of precursors of the individual active components, and the effect of their nature on the activity of the catalyst prepared have been studied. The samples prepared have been compared with selected commercial catalysts.

scholarly journals The Neuroprotective Role of Origanum syriacum L. and Lavandula dentata L. Essential Oils through Their Effects on AMPA Receptors

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Qneibi ◽  
Nidal Jaradat ◽  
Mohammed Hawash ◽  
Abdel Naser Zaid ◽  
Abdel-Razzak Natsheh ◽  
...  
Keyword(s):  
Essential Oils ◽  
Ampa Receptor ◽  
Ampa Receptors ◽  
Neurological Diseases ◽  
Critical Role ◽  
Hek293 Cells ◽  
Gas Chromatography Mass Spectrometry ◽  
Active Components ◽  
Study Results ◽  
Kinetics Of

Lavandula dentata L. and Origanum syriacum L. essential oils have numerous health benefits and properties, such as possessing common components with a variant degree of depressive actions in the central nervous system. We investigated the depressive property of these oils on AMPA receptors, which are responsible for most of the fast-excitatory neurotransmission in the CNS and play a critical role in synaptic plasticity. Since excessive activation of AMPARs has been linked to neurotoxicity leading to various pathologies, we hypothesize that these oils have a neuroprotective role by acting directly on the kinetics of AMPARs. Using Gas Chromatography-Mass Spectrometry (GC/MS) and patch-clamp electrophysiology, the essential oils of L. dentata flowers and O. syriacum leaves were characterized and the whole cell currents were measured with and without the administration of the oils onto HEK293 cells. The current study results showed that the biophysical properties of AMPA receptor subunits showed a decrease in desensitization rate of GluA1 and GluA2 homomers, using O. syriacum, while administering L. dentata oil decreased the desensitization rate of GluA1 and GluA2 homomers, as well as GluA1/2 heteromers. As for the deactivation rate, both oils slowed the deactivation kinetics of all AMPA receptor subunits. Intriguingly, between the two oils, the effect of desensitization and deactivation was of a greater significance for L. dentata oil than O. syriacum. Our data suggest that the two oils contain components that are essential to identify, as those active components underlie the oils’ neuronal depressive properties reported, and to extract them to synthesize a potent neuroprotective drug to treat neurological diseases potentially.

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