Ab Initio Studies on the Ziegler-Natta Polymerization Reaction Mechanisms. The Role of Cocatalysis

1994 ◽  
Vol 98 (46) ◽  
pp. 12053-12058 ◽  
Author(s):  
Shogo Sakai
Keyword(s):  
Ab Initio ◽  
Reaction Mechanisms ◽  
Polymerization Reaction

The role of density reduction in lithiated amorphous silicon: Molecular dynamics and ab-initio studies

2021 ◽  
Author(s):  
Jay Krishan Dora ◽  
Charchit Saraswat ◽  
Ashish Gour ◽  
Sudipto Ghosh ◽  
Natraj Yedla ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Amorphous Silicon ◽  
Density Reduction

Activators in Accelerated Sulfur Vulcanization

2004 ◽  
Vol 77 (3) ◽  
pp. 512-541 ◽  
Author(s):  
Geert Heideman ◽  
Rabin N. Datta ◽  
Jacques W. M. Noordermeer ◽  
Ben van Baarle
Keyword(s):  
Reaction Mechanisms ◽  
Model Compound ◽  
Background Information ◽  
Zinc Compounds ◽  
Chemical Mechanisms ◽  
Sulfur Vulcanization ◽  
Multifunctional Additives ◽  
Vulcanization Process

Abstract This review provides relevant background information about the vulcanization process, as well as the chemistry of thiuram- and sulfenamide-accelerated sulfur vulcanization with emphasis on the role of activators, to lay a base for further research. It commences with an introduction of sulfur vulcanization and a summary of the reaction mechanisms as described in literature, followed by the role of activators, particularly ZnO. The various possibilities to reduce ZnO levels in rubber compounding, that have been proposed in literature, are reviewed. A totally different approach to reduce ZnO is described in the paragraphs about the various possible roles of multifunctional additives (MFA) in rubber vulcanization. Another paragraph is dedicated to the role of amines in rubber vulcanization, in order to provide some insight in the underlying chemical mechanisms of MFA systems. Furthermore, an overview of Model Compound Vulcanization (MCV) with respect to different models and activator/accelerator systems is given. In the last part of this review, the various functions of ZnO in rubber are summarized. It clearly reveals that the role of ZnO and zinc compounds is very complex and still deserves further clarification.

On the role of hydrogen filled vacancies on the embrittlement of zirconium: An ab initio investigation

2015 ◽  
Vol 467 ◽  
pp. 311-319 ◽  
Author(s):  
Pär A.T. Olsson ◽  
Kwadwo Kese ◽  
Anna-Maria Alvarez Holston
Keyword(s):  
Ab Initio

scholarly journals Estrogen binding by leukocytes during phagocytosis,.

1977 ◽  
Vol 145 (4) ◽  
pp. 983-998 ◽  
Author(s):  
S J Klebanoff
Keyword(s):  
Chronic Granulomatous Disease ◽  
Reaction Mechanisms ◽  
Dehydrogenase Deficiency ◽  
Cell Types ◽  
Neutrophil Function ◽  
Granulomatous Disease ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Estrogen Binding ◽  
Two Populations

Estradiol binds covalently to normal leukocytes during phagocytosis. The binding involves three cell types, neutrophils, eosinophils, and monocytes and at least two reaction mechanisms, one involving the peroxidase of neutrophils and monocytes (myeloperoxidase [MPO]) and possibly the eosinophil peroxidase, and the second involving catalase. Binding is markedly reduced when leukocytes from patients with chronic granulomatous disease (CGD), severe leukocytic glucose 6-phosphate dehydrogenase deficiency, and familial lipochrome histiocytosis are employed and two populations of neutrophils, one which binds estradiol and one which does not, can be demonstrated in the blood of a CGD carrier. Leukocytes from patients with hereditary MPO deficiency also bind estradiol poorly although the defect is not as severe as in CGD. These findings are discussed in relation to the inactivation of estrogens during infection and the possible role of estrogens in neutrophil function.

Role of the Catalytic Triad and Oxyanion Hole in Acetylcholinesterase Catalysis:  An ab initio QM/MM Study

2002 ◽  
Vol 124 (35) ◽  
pp. 10572-10577 ◽  
Author(s):  
Yingkai Zhang ◽  
Jeremy Kua ◽  
J. Andrew McCammon
Keyword(s):  
Ab Initio ◽  
Catalytic Triad ◽  
Oxyanion Hole
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