NMR Characterization of Precursors to Chemically Derived Ceramics

1988 ◽  
Vol 121 ◽  
Author(s):  
John D. Basil ◽  
Chia-Cheng Lin
Keyword(s):  
Oxide Materials ◽  
Titanium Alkoxides ◽  
Reaction Parameters ◽  
Nmr Characterization ◽  
Hydrolysis And Condensation ◽  
Silicon Alkoxides ◽  
Ceramic Precursors ◽  
Insight Into

High resolution 29Si NMR spectroscopy has been used to study the hydrolysis and condensation reactions of TEOS and related silicon alkoxides under a range of conditions selected to model initial steps in the formation of ceramic precursors. Kinetic results have led to a detailed description of the role of various reaction parameters and to differences in reactivity of various polyethoxysiloxanes. Reactivity studies have provided insight into the processes that form multicomponent alkoxide/oxide materials. Titanium alkoxides in particular can act as catalysts for silanol condensation in addition to forming Si-O-Ti linkages, and the former role may predominate in certain systems.

scholarly journals Evidence that the TRPV1 S1-S4 Membrane Domain Contributes to Thermosensing

2019 ◽  
Author(s):  
Minjoo Kim ◽  
Nicholas J. Sisco ◽  
Jacob K. Hilton ◽  
Camila M. Montano ◽  
Manuel A. Castro ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Solution Nmr ◽  
Membrane Domain ◽  
Temperature Dependent ◽  
Nmr Characterization ◽  
Significant Interest ◽  
Pore Domain ◽  
Coupling Mechanisms

AbstractSensing and responding to temperature is crucial in biology. The TRPV1 ion channel is a well-studied heat-sensing receptor that is also activated by vanilloid compounds including capsaicin. Despite significant interest, the molecular underpinnings of thermosensing have remained elusive. The TRPV1 S1-S4 membrane domain couples chemical ligand binding to the pore domain during channel gating. However, the role of the S1-S4 domain in thermosensing is unclear. Evaluation of the isolated human TRPV1 S1-S4 domain by solution NMR, Far-UV CD, and intrinsic fluorescence shows that this domain undergoes a non-denaturing temperature-dependent transition with a high thermosensitivity. Further NMR characterization of the temperature-dependent conformational changes suggests the contribution of the S1-S4 domain to thermosensing shares features with known coupling mechanisms between this domain with ligand and pH activation. Taken together, this study shows that the TRPV1 S1-S4 domain contributes to TRPV1 temperature-dependent activation.

Histolocalization and physico-chemical characterization of dihydrochalcones: Insight into the role of apple major flavonoids

2013 ◽  
Vol 90 ◽  
pp. 78-89 ◽  
Author(s):  
Matthieu Gaucher ◽  
Thomas Dugé de Bernonville ◽  
David Lohou ◽  
Sylvain Guyot ◽  
Thomas Guillemette ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Physico Chemical ◽  
Insight Into

The use of multinuclear solid state NMR for the characterization of siloxane-oxide hybrid nanocomposites

2004 ◽  
Vol 847 ◽  
Author(s):  
Christel Gervais ◽  
Beatriz Julián ◽  
Eloisa Cordoncillo ◽  
Purificación Escribano ◽  
Mark E. Smith ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
Sol Gel Process ◽  
Hydrolysis And Condensation ◽  
Silicon Alkoxides ◽  
Different Types ◽  
Nmr Techniques

ABSTRACTThe objective of this paper is to review various solid state NMR techniques that have been, or can be used for the structural characterization of siloxane—oxide hybrid systems prepared by sol-gel process, and to discuss the type of information they provide, as well as their limitations. More precisely, this paper focuses on NMR techniques to probe and quantify the different types of oxo-bridges (M–O–M of oxide network, Si–O–Si of siloxane chains and Si–O–M siloxane–MxOy interface) in siloxane-oxide nanocomposites prepared through hydrolysis and condensation of organosilanes and M(OR)n alkoxides. In addition the influence of the functionality of the silicon alkoxides and the nature of the MxOy oxides on the extent of the Si-O-M interface will be examined.

scholarly journals The pathophysiology of sepsis—2021 update: Part 1, immunology and coagulopathy leading to endothelial injury

2021 ◽  
Author(s):  
Judith Jacobi
Keyword(s):  
Treatment Options ◽  
Endothelial Injury ◽  
Coagulation Cascade ◽  
Secondary Infections ◽  
Sepsis And Septic Shock ◽  
Risk And Benefit ◽  
Insight Into ◽  
Related Mortality

Abstract Disclaimer In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. Purpose To provide an overview of current literature on the pathophysiology of sepsis, with a focus on mediators of endothelial injury and organ dysfunction. Summary Sepsis is a dysregulated response to infection that triggers cascades of interconnected systems. Sepsis has been a significant cause of mortality worldwide, and the recent viral pandemic that may produce severe sepsis and septic shock has been a major contributor to sepsis-related mortality. Understanding of the pathophysiology of sepsis has changed dramatically over the last several decades. Significant insight into the components of the inflammatory response that contribute to endothelial injury and trigger coagulation pathways has been achieved. Similarly, characterization of anti-inflammatory pathways that may lead to secondary infections and poor outcome has illustrated opportunities for improved therapies. Description of an increasing number of important mediators and pathways has occurred and may point the way to novel therapies to address immune dysregulation. Pharmacists will need a fundamental understanding of the overlapping pathways of the immune response to fully prepare for use of novel treatment options. While pharmacists typically understand coagulation cascade how to utilize anticoagulants, the issues in sepsis related coagulopathy and role of mediators such as cytokines and complement and role of activated platelets and neutrophils require a different perspective. Conclusion Pharmacists can benefit from understanding both the cellular and organ system issues in sepsis to facilitate assessment of potential therapies for risk and benefit.

scholarly journals The Role of Hydraulic Hysteresis on the Hydrological Response of Pyroclastic Silty Covers

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 628 ◽  
Author(s):  
Guido Rianna ◽  
Luca Comegna ◽  
Luca Pagano ◽  
Luciano Picarelli ◽  
Alfredo Reder
Keyword(s):  
Slope Failure ◽  
Hysteretic Behavior ◽  
Recent Experience ◽  
Hydrological Response ◽  
Hydraulic Hysteresis ◽  
The Stability ◽  
Hydrological Effects ◽  
Insight Into

A significant part of the recent geotechnical literature concerning pyroclastic soils is focused on the characterization of the hydrological effects of precipitations and their implications for the stability conditions of unsaturated sloping covers. Recent experience shows that suction-induced strength reduction is influenced by various factors including hydraulic hysteresis. A deeper insight into the hysteretic water retention behavior of these materials and its effects upon their response to dry/wetting conditions is a major goal of this paper, which exploits the data provided by the monitoring of a volcanic ash. Based on the parameters retrieved from data calibration, the hydrological response of a virtual slope subject to one-dimensional rainfall infiltration is investigated by numerical analyses and compared with the results obtained through the usually adopted non-hysteretic approaches. The analysis demonstrates that considering the hysteretic behavior may be crucial for a proper evaluation of the conditions leading to slope failure.

Solid-State Carbon-13 NMR Studies of Vulcanized Elastomers. VII. Sulfur-Vulcanized Cis-1,4 Polybutadiene at 75.5 Mhz

1989 ◽  
Vol 62 (5) ◽  
pp. 908-927 ◽  
Author(s):  
R. S. Clough ◽  
J. L. Koenig
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Chemical Information ◽  
Chemical Probes ◽  
Nmr Studies ◽  
Nmr Characterization ◽  
The Individual ◽  
Insight Into

Abstract Solid-state C-13 NMR spectroscopy provides a wealth of chemical information concerning sulfur-vulcanized cis-l,4-polybutadiene. New resonances which appear upon curing have chemical shifts which are expected for crosslink and cyclic structures. The DEPT experiment with MAS worked well for the polybutadiene vulcanizate in the solid state. DEPT is very useful as an aid in the assignment of structures to resonances. The new resonances can be assigned to more than one type of structure given only chemical shift and DEPT information. Swelling measurements indicate the majority of the resonances are due to cyclics. Further work involving C-13 NMR characterization of polybutadiene vulcanizates treated with chemical probes and vulcanizates cured with organic accelerators should provide insight into the specific structures responsible for the individual resonances.

scholarly journals Characterization of vegetative inflorescence (mc-vin) mutant provides new insight into the role of MACROCALYX in regulating inflorescence development of tomato

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Fernando J. Yuste-Lisbona ◽  
Muriel Quinet ◽  
Antonia Fernández-Lozano ◽  
Benito Pineda ◽  
Vicente Moreno ◽  
...  
Keyword(s):  
Inflorescence Development ◽  
Insight Into

scholarly journals Characterization of a Latent Virus-Like Infection of Symbiotic Zooxanthellae

2007 ◽  
Vol 73 (9) ◽  
pp. 2976-2981 ◽  
Author(s):  
Jayme Lohr ◽  
Colin B. Munn ◽  
William H. Wilson
Keyword(s):  
Uv Light ◽  
Latent Virus ◽  
Thin Sections ◽  
Virus Like Particles ◽  
Transmission Electron ◽  
Uv Irradiance ◽  
Virus System ◽  
Insight Into

ABSTRACT A latent virus-like agent, which we designated zooxanthella filamentous virus 1 (ZFV1), was isolated from Symbiodinium sp. strain CCMP 2465 and characterized. Transmission electron microscopy and analytical flow cytometry revealed the presence of a new group of distinctive filamentous virus-like particles after exposure of the zooxanthellae to UV light. Examination of thin sections of the zooxanthellae revealed the formation and proliferation of filamentous virus-like particles in the UV-induced cells. Assessment of Symbiodinium sp. cultures was used here as a model to show the effects of UV irradiance and induction of potential latent viruses. The unique host-virus system described here provides insight into the role of latent infections in zooxanthellae through environmentally regulated viral induction mechanisms.

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