New Perspective on the Kinetics of Enzyme Catalysis

1995 ◽  
Vol 99 (17) ◽  
pp. 6595-6600 ◽  
Author(s):  
John Happel ◽  
Peter H. Sellers
Keyword(s):  
Enzyme Catalysis ◽  
New Perspective ◽  
Kinetics Of

Kinetics of Enzyme Catalysis

2022 ◽  
Author(s):  
Bruce Han Palfey ◽  
Rebecca Switzer
Keyword(s):  
Enzyme Catalysis ◽  
Kinetics Of

scholarly journals Understanding Hydrodechlorination of Chloromethanes. Past and Future of the Technology

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1462
Author(s):  
Sichen Liu ◽  
Javier A. Otero ◽  
Maria Martin-Martinez ◽  
Daniel Rodriguez-Franco ◽  
Juan J. Rodriguez ◽  
...  
Keyword(s):  
Catalyst Deactivation ◽  
Global Analysis ◽  
Catalytic Performance ◽  
Operating Conditions ◽  
Light Olefins ◽  
Synthesis Methods ◽  
Chlorinated Pollutants ◽  
New Perspective ◽  
Kinetics Of ◽  
Experimental And Theoretical Studies

Chloromethanes are a group of volatile organic compounds that are harmful to the environment and human health. Abundant studies have verified that hydrodechlorination might be an effective treatment to remove these chlorinated pollutants. The most outstanding advantages of this technique are the moderate operating conditions used and the possibility of obtaining less hazardous valuable products. This review presents a global analysis of experimental and theoretical studies regarding the hydrodechlorination of chloromethanes. The catalysts used and their synthesis methods are summarized. Their physicochemical properties are analyzed in order to deeply understand their influence on the catalytic performance. Moreover, the main causes of the catalyst deactivation are explained, and prevention and regeneration methods are suggested. The reaction systems used and the effect of the operating conditions on the catalytic activity are also analyzed. Besides, the mechanisms and kinetics of the process at the atomic level are reviewed. Finally, a new perspective for the upgrading of chloromethanes, via hydrodechlorination, to valuable hydrocarbons for industry, such as light olefins, is discussed.

scholarly journals A new perspective of the chemistry and kinetics of inactivation of COVID -19 coronavirus aerosols

2021 ◽  
Author(s):  
Michael L Hitchman
Keyword(s):  
Uv Light ◽  
Practical Method ◽  
Viral Envelope ◽  
Chain Reaction ◽  
Radical Chain ◽  
Enveloped Virus ◽  
Rate Kinetics ◽  
New Perspective ◽  
Free Radical Chain Reaction ◽  
Kinetics Of

In this paper we present a new approach to the mechanism of inactivation of enveloped virus aerosols. The analysis is in terms of oxidation of the lipid bilayer of the viral envelope through a free radical chain reaction. The rate kinetics of the process for various enveloped viruses have been compared and the indications are that the inactivations are closely related. Promoting virus inactivation with UV light is briefly reviewed and discussed as an extension of the chain reaction mechanism, which with physicochemical analyses give insights into the process and of reaction complexities. An outline of a practical method of achieving a 3-log10 level of deactivation in 1 min is described with purified air being returned to healthcare environments.

scholarly journals A New Perspective on Fluorapatite Dissolution in Hydrochloric Acid: Thermodynamic Calculations and Experimental Study

Inorganics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 65
Author(s):  
Kaia Tõnsuaadu ◽  
Juha Kallas ◽  
Rein Kuusik ◽  
Gizem Hacialioglu-Erlenheim ◽  
Andres Trikkel
Keyword(s):  
Dissolution Rate ◽  
Thermodynamic Calculations ◽  
Ph Change ◽  
Secondary Reactions ◽  
Solid Part ◽  
New Perspective ◽  
Kinetics Of Dissolution ◽  
Hcl Concentration ◽  
The Relationship ◽  
Kinetics Of

Apatite (Ap) dissolution in diluted acids is well described in the literature, but in technological processes which use more concentrated acids, the reaction is fast, and it is complicated to follow the process kinetics. The relationship between pH change and the apatite dissolution rate depending on HCl concentration was studied by thermodynamic calculations and experiments with synthetic fluorapatite (FAp). On the basis of experimental pH measurements, the kinetics of dissolution was analyzed. The solution composition (P, Ca, F) was determined by wet chemical methods and the solid part was characterized by XRD and FTIR. It was shown that the amount of HCl needed for FAp dissolution depends on acid concentration. FAp dissolution rate cannot be deduced from solubility data of P, Ca or F as the secondary reactions of CaF2 and CaHPO4 formation take place simultaneously. It was found that the Ap dissolution rate can be followed by pH change.

scholarly journals The Kinetics of Amyloid Fibril Formation by de Novo Protein Albebetin and Its Mutant Variants

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 241
Author(s):  
Vitalii Balobanov ◽  
Rita Chertkova ◽  
Anna Egorova ◽  
Dmitry Dolgikh ◽  
Valentina Bychkova ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
De Novo ◽  
Point Mutations ◽  
Inhibitory Effect ◽  
Structural Basis ◽  
Amyloid Formation ◽  
Amyloid Fibril Formation ◽  
External Conditions ◽  
New Perspective ◽  
Kinetics Of

Engineering of amyloid structures is one of the new perspective areas of protein engineering. Studying the process of amyloid formation can help find ways to manage it in the interests of medicine and biotechnology. One of the promising candidates for the structural basis of artificial functional amyloid fibrils is albebetin (ABB), an artificial protein engineered under the leadership of O.B. Ptitsyn. Various aspects of the amyloid formation of this protein and some methods for controlling this process are investigated in this paper. Four stages of amyloid fibrils formation by this protein from the first non-fibrillar aggregates to mature fibrils and large micron-sized complexes have been described in detail. Dependence of albebetin amyloids formation on external conditions and some mutations also have been described. The introduction of similar point mutations in the two structurally identical α-β-β motifs of ABB lead to different amiloidogenesis kinetics. The inhibitory effect of a disulfide bond and high pH on amyloid fibrils formation, that can be used to control this process, was shown. The results of this work are a good basis for the further design and use of ABB-based amyloid constructs.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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