Temperature Dependence of Peptide Conformational Equilibria from Simulations at a Single Temperature

2021 ◽  
Vol 125 (11) ◽  
pp. 2374-2384
Author(s):  
Ankita Katiyar ◽  
Ward H. Thompson
Keyword(s):  
Temperature Dependence ◽  
Single Temperature ◽  
Conformational Equilibria

Temperature Dependence of the Conformational Equilibria of Cyclic Sulfites

1965 ◽  
Vol 30 (12) ◽  
pp. 4363-4364 ◽  
Author(s):  
C. G. Overberger ◽  
T. Kurtz ◽  
S. Yaroslavsky
Keyword(s):  
Temperature Dependence ◽  
Conformational Equilibria ◽  
Cyclic Sulfites

ALICYCLIC KETYLS: II. TEMPERATURE DEPENDENCE OF THE CONFORMATIONAL MOBILITY OF MEDIUM-SIZED RINGS

1965 ◽  
Vol 43 (12) ◽  
pp. 3294-3303 ◽  
Author(s):  
J. W. Lown
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Close Agreement ◽  
Conformational Equilibrium ◽  
Dihedral Angles ◽  
Paramagnetic Resonance ◽  
Conformational Equilibria ◽  
Electron Paramagnetic ◽  
Hyperfine Couplings

The electron paramagnetic resonance spectra of ketyls derived from alicyclic ketones containing from 6 to 12 carbons have been recorded in 1,2-dimethoxyethane or dimethoxymethane at temperatures from −96 to +87 °C. At −96° individual conformers of the cyclohexyl ketyl are observed with hyperfine couplings in close agreement with that of the conformationally 'frozen' 4-tert-butyl analogue at room temperature. The cycloheptyl ketyl conformational equilibrium between forms which have a plane of symmetry through the C—O bond axis is 'frozen' with respect to the spectrometer frequency at temperatures from −40 to +88 °C. Cyclooctyl ketyl equilibrates at ordinary temperatures between two conformers lacking a plane of symmetry through the C—O bond axis. The electron paramagnetic resonance spectra of the ketyls derived from 10- and 12-membered rings show dramatic temperature dependence, which is interpreted in terms of two or more simultaneous conformational equilibria. Values for the dihedral angles of the alpha protons and for the spin density on the sp2 carbon are derived.

SPECTROSCOPIC STUDIES OF ALCOHOLS: VI. INTRAMOLECULAR HYDROGEN BONDS IN ETHANOLAMINE AND ITS O- AND N-METHYL DERIVATIVES

1965 ◽  
Vol 43 (11) ◽  
pp. 2970-2977 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Temperature Dependence ◽  
Spectroscopic Studies ◽  
Intramolecular Hydrogen Bonds ◽  
Distinct Band ◽  
Conformational Equilibria ◽  
Methyl Derivatives ◽  
Intramolecular Hydrogen

The competitive intramolecular [Formula: see text] hydrogen bonding in ethanolamine and N-methylethanolamine has been studied in dilute C2Cl4 solution by means of the temperature dependence of the fundamental OH and NH stretching bands. Of the three conformers identified for each of these compounds, the least stable shows a distinct band which is assigned to a "terminal" OH group involved in an intramolecular [Formula: see text] hydrogen bond. Enthalpy differences between conformers are reported and discussed, and compared with those found for the conformational equilibria in 2-methoxyethylamine and N,N-dimethyl-ethanolamine.

Nuclear magnetic resonance study of conformational equilibria in some fluorinated alkenes

1964 ◽  
Vol 282 (1391) ◽  
pp. 559-568 ◽  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Opposite Sign ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Study ◽  
Close Proximity ◽  
Conformational Equilibria ◽  
Enthalpy Difference

From a temperature study of coupling constants in cis and trans i -C 3 F 7 CH═CHF several coupling constants characteristic of the fixed rotamers have been calculated. The observed temperature dependence is consistent with there being only two rotamers of significant population for each isomer. The enthalpy difference between rotamers is – 1700 and – 900 cal/mole for the cis and trans isomers respectively. Long-range F–F coupling constants appear to be large where the interacting nuclei are in close proximity. Some of the coupling constants are found to be of opposite sign when the isomers change their conformations.

scholarly journals Modelling the effect of temperature on the probabilistic stress–life fatigue diagram of glass fibre–polymer composites loaded in tension along the fibre direction

2017 ◽  
Vol 52 (2) ◽  
pp. 207-224 ◽  
Author(s):  
Laurent Cormier ◽  
Simon Joncas
Keyword(s):  
Fatigue Life ◽  
Temperature Dependence ◽  
Polymer Composites ◽  
Static Strength ◽  
Fatigue Performance ◽  
Effect Of Temperature ◽  
Model Parameters ◽  
Fibre Direction ◽  
Single Temperature ◽  
Different Temperatures

Predicting the fatigue performance of composites has proven to be a challenge both conceptually, due to the inherent complexity of the phenomenon, and practically, because of the resource-intensive process of fatigue testing. Moreover, mechanical behaviour of polymer matrix composites exhibits a complicated temperature dependence, making the prediction of fatigue performance under different temperatures even more complex and resource intensive. The objective of this paper is to provide a method for the prediction of fatigue life of glass–polymer composites loaded in the fibre direction at various temperatures with minimal experimental efforts. This is achieved by using a static strength degradation approach to fatigue modelling, where only two parameters (including static strength) are temperature dependent, in conjunction with relationships for these two fatigue model parameters temperature dependence. The method relies on fatigue data at a single temperature and simple static tests at different temperatures to predict the effects of temperature on the material’s fatigue behaviour. The model is validated on experimental data for two unidirectional and one woven glass–epoxy composites and is found to accurately predict the effect of temperature on fatigue life of composites. A method to obtain probabilistic stress-life [Formula: see text] fatigue diagrams including temperature effects is also presented.

Temperature dependence of tryptophan and tyrosine luminescence in poly(vinyl alcohol) films

1981 ◽  
Vol 34 (7) ◽  
pp. 1367 ◽  
Author(s):  
R Sakurovs ◽  
KP Ghiggino
Keyword(s):  
Triplet State ◽  
Temperature Dependence ◽  
Vinyl Alcohol ◽  
Kinetic Scheme ◽  
Activation Energies ◽  
Poly Vinyl Alcohol ◽  
Luminescent Probes ◽  
Single Temperature ◽  
Distinct Temperature

The temperature dependence of the fluorescence and phosphorescence from tyrosine and tryptophan in poly(vinyl alcohol) films has been studied over the temperature range 90-295 K. A kinetic scheme is proposed which allows the calculation of activation energies for excited singlet and triplet state deactivation processes. A single temperature-dependent radiationless process from the singlet state is observed for tyrosine and tryptophan, with activation energies of 5.2�0.4 and 7.1�0.6 kJ mol-1 respectively. However, two distinct temperature transitions have been detected for triplet-state relaxation at 180 and 255 K. The role of polymer phase transitions in determining excited state relaxation pathways of embedded luminescent probes is discussed.

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