Intrinsic alterations in the hydrogen desorption of Mg2NiH4 by solid dissolution of titanium

2018 ◽  
Vol 47 (25) ◽  
pp. 8418-8426 ◽  
Author(s):  
Pengfei Wei ◽  
Wen Huang ◽  
Xiaoli Ding ◽  
Yongtao Li ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Phase Boundary ◽  
Boundary Migration ◽  
Three Dimensional ◽  
Hydrogen Desorption ◽  
Two Dimensional ◽  
Rate Limiting Step ◽  
Dimensional Diffusion ◽  
Limiting Step ◽  
Rate Limiting

The rate-limiting step for Mg2NiH4 desorption was intrinsically shifted from three-dimensional diffusion to two-dimensional phase boundary migration by titanium dissolution.

Devitrification kinetics and mechanism of Pyrex borosilicate glass

2001 ◽  
Vol 16 (6) ◽  
pp. 1752-1758 ◽  
Author(s):  
Jau-Ho Jean ◽  
Yu-Ching Fang
Keyword(s):  
Borosilicate Glass ◽  
Linear Growth ◽  
Energy Analysis ◽  
Three Dimensional ◽  
Rate Limiting Step ◽  
Dimensional Diffusion ◽  
Limiting Step ◽  
Diffusion Controlled ◽  
Rate Limiting ◽  
Kinetics Of

Cristobalite is formed when initially amorphous Pyrex borosilicate glass (Corning 7740) is fired at temperatures ranging from 700 to 1000 °C. The sigmoidal devitrification kinetics of cristobalite obeys Avrami-like three-dimensional diffusion-controlled kinetics. Activation energy analysis indicates that the diffusion of Na+ in the glass is the rate-limiting step during phase transformation. The above conclusion is further confirmed by calculated and measured results of linear growth rates.

scholarly journals Exploiting two-dimensional morphology of molybdenum oxycarbide to enable efficient catalytic dry reforming of methane

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexey Kurlov ◽  
Evgeniya B. Deeva ◽  
Paula M. Abdala ◽  
Dmitry Lebedev ◽  
Athanasia Tsoukalou ◽  
...  
Keyword(s):  
Contact Time ◽  
Specific Activity ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Two Dimensional ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Oxygen Coverage ◽  
Rate Limiting

Abstract The two-dimensional morphology of molybdenum oxycarbide (2D-Mo2COx) nanosheets dispersed on silica is found vital for imparting high stability and catalytic activity in the dry reforming of methane. Here we report that owing to the maximized metal utilization, the specific activity of 2D-Mo2COx/SiO2 exceeds that of other Mo2C catalysts by ca. 3 orders of magnitude. 2D-Mo2COx is activated by CO2, yielding a surface oxygen coverage that is optimal for its catalytic performance and a Mo oxidation state of ca. +4. According to ab initio calculations, the DRM proceeds on Mo sites of the oxycarbide nanosheet with an oxygen coverage of 0.67 monolayer. Methane activation is the rate-limiting step, while the activation of CO2 and the C–O coupling to form CO are low energy steps. The deactivation of 2D-Mo2COx/SiO2 under DRM conditions can be avoided by tuning the contact time, thereby preventing unfavourable oxygen surface coverages.

scholarly journals Iterative screen optimization maximizes the efficiency of macromolecular crystallization

2019 ◽  
Vol 75 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Harrison G. Jones ◽  
Daniel Wrapp ◽  
Morgan S. A. Gilman ◽  
Michael B. Battles ◽  
Nianshuang Wang ◽  
...  
Keyword(s):  
Narrow Range ◽  
Three Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Crystallization Experiment ◽  
Automated Process ◽  
Macromolecular Crystallization ◽  
Rate Limiting

Advances in X-ray crystallography have streamlined the process of determining high-resolution three-dimensional macromolecular structures. However, a rate-limiting step in this process continues to be the generation of crystals that are of sufficient size and quality for subsequent diffraction experiments. Here, iterative screen optimization (ISO), a highly automated process in which the precipitant concentrations of each condition in a crystallization screen are modified based on the results of a prior crystallization experiment, is described. After designing a novel high-throughput crystallization screen to take full advantage of this method, the value of ISO is demonstrated by using it to successfully crystallize a panel of six diverse proteins. The results suggest that ISO is an effective method to obtain macromolecular crystals, particularly for proteins that crystallize under a narrow range of precipitant concentrations.

Ornithine Decarboxylase Activity in Cultured Endothelial Cells Stimulated by Serum, Thrombin and Serotonin

1978 ◽  
Vol 39 (02) ◽  
pp. 496-503 ◽  
Author(s):  
P A D’Amore ◽  
H B Hechtman ◽  
D Shepro
Keyword(s):  
Endothelial Cells ◽  
Ornithine Decarboxylase ◽  
Decarboxylase Activity ◽  
Aortic Endothelial Cells ◽  
Ornithine Decarboxylase Activity ◽  
Rate Limiting Step ◽  
Bovine Aortic Endothelial Cells ◽  
Limiting Step ◽  
Rate Limiting ◽  
Serum Serotonin

SummaryOrnithine decarboxylase (ODC) activity, the rate-limiting step in the synthesis of polyamines, can be demonstrated in cultured, bovine, aortic endothelial cells (EC). Serum, serotonin and thrombin produce a rise in ODC activity. The serotonin-induced ODC activity is significantly blocked by imipramine (10-5 M) or Lilly 11 0140 (10-6M). Preincubation of EC with these blockers together almost completely depresses the 5-HT-stimulated ODC activity. These observations suggest a manner by which platelets may maintain EC structural and metabolic soundness.

Dynamics of hepatic and peripheral insulin effects suggest common rate-limiting step in vivo

Diabetes ◽  
1993 ◽  
Vol 42 (2) ◽  
pp. 296-306 ◽  
Author(s):  
D. C. Bradley ◽  
R. A. Poulin ◽  
R. N. Bergman
Keyword(s):  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting
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