SP–PLP–EPR Measurement of Iron-Mediated ATRP Deactivation Rate

2015 ◽  
Vol 48 (17) ◽  
pp. 6108-6113 ◽  
Author(s):  
Hendrik Schroeder ◽  
Michael Buback
Keyword(s):  
Deactivation Rate

Atomic Layer Deposition for Improved Stability of Catalysts for the Conversion of Biomass to Chemicals and Fuels

2011 ◽  
Vol 1366 ◽  
Author(s):  
Monika K. Wiedmann ◽  
Yomaira J. Pagan-Torres ◽  
Mark H. Tucker ◽  
James A. Dumesic ◽  
T. F. Kuech
Keyword(s):  
Atomic Layer Deposition ◽  
Metal Oxides ◽  
Rate Constant ◽  
Flow Reactor ◽  
Atomic Layer ◽  
Deactivation Rate ◽  
Layer Deposition ◽  
Improved Stability ◽  
Deactivation Rate Constant ◽  
Acid Catalyzed

ABSTRACTAtomic layer deposition (ALD) has been used to coat SBA-15 and functionalized SBA-15 with various metal oxides. Use of SBA-15 coated with 4-10 ALD cycles of titania, alumina, niobia, or zirconia in the acid-catalyzed dehydration of fructose to 5-hydroxymethylfurfural (HMF) resulted in 24-57% conversion, with 0-22% selectivity, at 130 °C with 2 wt % fructose in 4:1 THF:H2O. Propylsulfonic acid functionalized SBA-15 (SBA-15-PrSO3H) had a 25% conversion and 48% selectivity for HMF under the same conditions. SBA-15-PrSO3H was also coated with 2 ALD cycles of titania followed by 8 ALD cycles silica. The deactivation rate constant for SBA-15-PrSO3H was 2.7 x 10-2 h-1 for the dehydration of fructose to HMF in a flow reactor at 130 °C with a feed of 2 wt % fructose in 4:1 THF:H2O. In comparison, the deactivation rate constant for the ALD coated SBA-15-PrSO3H-ALD was 7.9 x 10-3 h-1.

scholarly journals Acidification of Rat TRPV1 Alters the Kinetics of Capsaicin Responses

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-28 ◽  
Author(s):  
Torben R Neelands ◽  
Michael F Jarvis ◽  
Ping Han ◽  
Connie R Faltynek ◽  
Carol S Surowy
Keyword(s):  
Acidic Ph ◽  
Hek 293 ◽  
Deactivation Rate ◽  
Vanilloid Receptor 1 ◽  
293 Cells ◽  
Activation Rate ◽  
Current Activation ◽  
Acidic Conditions ◽  
Tissue Acidosis ◽  
Trpv1 Antagonist

TRPV1 (vanilloid receptor 1) receptors are activated by a variety of ligands such as capsaicin, as well as by acidic conditions and temperatures above 42°C. These activators can enhance the potency of one another, shifting the activation curve for TRPV1 to the left. In this study, for example, we observed an approximately 10-fold shift in the capsaicin EC50 (640 nM to 45 nM) for rat TRPV1 receptors expressed in HEK-293 cells when the pH was lowered from 7.4 to 5.5. To investigate potential causes for this shift in capsaicin potency, the rates of current activation and deactivation of whole-cell currents were measured in individual cells exposed to treatments of pH 5.5, 1 μM capsaicin or in combination. Acidic pH was found to both increase the activation rate and decrease the deactivation rate of capsaicin-activated currents providing a possible mechanism for the enhanced potency of capsaicin under acidic conditions. Utilizing a paired-pulse protocol, acidic pH slowed the capsaicin deactivation rate and was readily reversible. Moreover, the effect could occur under modestly acidic conditions (pH 6.5) that did not directly activate TRPV1. When TRPV1 was maximally activated by capsaicin and acidic pH, the apparent affinity of the novel and selective capsaicin-site competitive TRPV1 antagonist, A-425619, was reduced ∼35 fold. This shift was overcome by reducing the capsaicin concentration co-applied with acidic pH. Since inflammation is associated with tissue acidosis, these findings enhance understanding of TRPV1 receptor responses in inflammatory pain where tissue acidosis is prevalent.

Collisional Deactivation Rates of Electronically Excited Molecular Ions. II

1972 ◽  
Vol 50 (1) ◽  
pp. 1-7 ◽  
Author(s):  
G. I. Mackay ◽  
R. E. March
Keyword(s):  
Rate Constants ◽  
Radiative Lifetime ◽  
Molecular Ions ◽  
Deactivation Rate ◽  
Complete Knowledge ◽  
Induced Dipole ◽  
Excited Species ◽  
Vibrational Levels ◽  
Electronically Excited ◽  
Deactivation Rate Constant

Total deactivation rate constants have been determined for N2+(B2Σu+) and the (A2Πu) and (B2Σu+) states of CO2+ with a number of quenchers. The energy specific total deactivation rate constant is compared to the total radiative lifetime of the excited species. A particular novelty of the technique is that it does not require a complete knowledge of the formation modes for the excited species. The results are compared with theoretical values obtained from the ion-induced dipole model. Individual deactivation rate constants are presented for N2+(B2Σu+) ions in the v = 0, 1, and 2 vibrational levels quenched by N2, O2, H2, and CO2; and for the(A2Πu) and (B2Σu+) states of CO2+ quenched byCO2, N2, O2, NO, and H2. Charge transfer is the most probable mode of deactivation except in the CO2+–H2 reactions where H-atom abstraction is more probable.

A low-deactivation-rate Lewis acid zeolite prepared in an alkali metal ion-containing system for alkene epoxidation

RSC Advances ◽  
2016 ◽  
Vol 6 (100) ◽  
pp. 98514-98519 ◽  
Author(s):  
Kai-Rui Fu ◽  
Ji-Kang Yao ◽  
Qiang Xiao ◽  
Hai-Xia Liu ◽  
Tian-Duo Li ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Lewis Acid ◽  
Metal Ion ◽  
Catalytic Performance ◽  
Alkali Metal Ion ◽  
Deactivation Rate ◽  
Acid Zeolites

The best catalytic performance among the currently reported TS-1 Lewis acid zeolites is achieved due to its durable catalytic life.

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