scholarly journals Mesophase behaviour of a cyanobiphenyl molecule in polar aprotic solvent: Rigidity effect

2020 ◽  
Vol 31 (3) ◽  
pp. 33-45
Author(s):  
Suraj Kumar Nayak ◽  
◽  
P. Lakshmi Praveen ◽  
Keyword(s):  
Transition Temperature ◽  
Room Temperature ◽  
Theoretical Study ◽  
Aprotic Solvent ◽  
Molecular Models ◽  
Polar Aprotic Solvent ◽  
Rigidity Parameter ◽  
The Stability ◽  
Modes Of Interaction ◽  
Crystal Compound

In this paper, a theoretical study has been carried out on a liquid crystal compound named p-n-propyl cyanobiphenyl (3CB). The different modes of interaction energy values in a polar aprotic solvent (ethyl acetate) for small amount of translation and rotation are calculated. The corresponding probabilities have been calculated at both room temperature (300 K) and transition temperature (303.3 K). The rigidity parameter for stacking and in-plane interactions has been estimated and then the stability of molecule according to probability and rigidity at definite translation and rotation has been concluded. The change in the characteristics and stability of the compound at transition temperature has been observed. The dependence of mesophase behaviour with change in the certain configurations and orientation of the molecules have been discussed. These observed results provide an insight about the process of mesophase structure and its formation. The present compound may guide in establishing the other molecular models with transition temperature nearer to room temperature.

Solvolysis of sulphonyl halides. VIII. Reaction of methane and ethane sulphony1 chlorides with methanol, ethanol, and mixed solvent systems

1971 ◽  
Vol 24 (4) ◽  
pp. 713 ◽  
Author(s):  
R Foon ◽  
AN Hambly
Keyword(s):  
Carbon Tetrachloride ◽  
Room Temperature ◽  
Reaction Rate ◽  
Mixed Solvent ◽  
Aprotic Solvent ◽  
Excess Enthalpies ◽  
Initial State ◽  
Polar Aprotic Solvent ◽  
Rate Of Reaction ◽  
Solvent Systems

At room temperature methanesulphonyl chloride reacts more rapidly than ethanesulphonyl chloride in solvolysis by ethanol. Their rates of reaction with methanol are approximately equal while ethanesulphonyl chloride is the more reactive in hydrolysis. The enthalpies and entropies of activation have been determined for the solvolysis of ethanesulphonyl chloride in mixtures of ethanol with benzene, carbon tetrachloride, or 2,2,4-trimethylpentane. A comparison of the excess enthalpies and entropies of mixing in the formation of these solvents with the corresponding parameters for reaction shows that the effects on reaction rate are not due merely to the modification of the initial state of the system. The effect of the polar aprotic solvent nitrobenzene on the rate of reaction with methanol is attributed to an increase in the nucleophilic tendency of the methanol rather than to solvation of the reactive centre in the transition state.

scholarly journals Strong Binding of Noble Gases to [B12X11]˗: A Theoretical Study

2021 ◽  
Author(s):  
Kevin Wöhner ◽  
Toshiki Wulf ◽  
Nina Vankova ◽  
Thomas Heine
Keyword(s):  
Charge Transfer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Noble Gases ◽  
Theoretical Study ◽  
Ion Trap ◽  
Noble Gas ◽  
Capture Reaction ◽  
Strong Binding ◽  
The Stability

We systematically explore the stability and properties of [B<sub>12</sub>X<sub>11</sub>Ng]<sup>−</sup> adducts resulting from the capture reaction of noble gas atoms (Ng) by anionic [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> clusters in the ion trap. [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> can be obtained by stripping one X<sup>−</sup> ligand off the icosahedral <i>closo</i>-dodecaborate dianion [B<sub>12</sub>X<sub>12</sub>]<sup>2</sup><sup>−</sup>. We study the binding of the noble gas atoms He, Ne, Kr, Ar and Xe to [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> with ligands X = F, Cl, Br, I, CN. While He cannot be captured by these clusters and Ne only binds at low temperatures, the complexes with the heavier Kr, Ar and Xe show appreciable complexation energies and exceed 1 eV at room temperature in the case of [B<sub>12</sub>(CN)<sub>11</sub>Xe]<sup>−</sup>. For the latter three noble gases, we observe a significant charge transfer from the Ng to the icosahedral B<sub>12</sub> cage.

scholarly journals Strong Binding of Noble Gases to [B12X11]˗: A Theoretical Study

2021 ◽  
Author(s):  
Kevin Wöhner ◽  
Toshiki Wulf ◽  
Nina Vankova ◽  
Thomas Heine
Keyword(s):  
Charge Transfer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Noble Gases ◽  
Theoretical Study ◽  
Ion Trap ◽  
Noble Gas ◽  
Capture Reaction ◽  
Strong Binding ◽  
The Stability

We systematically explore the stability and properties of [B<sub>12</sub>X<sub>11</sub>Ng]<sup>−</sup> adducts resulting from the capture reaction of noble gas atoms (Ng) by anionic [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> clusters in the ion trap. [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> can be obtained by stripping one X<sup>−</sup> ligand off the icosahedral <i>closo</i>-dodecaborate dianion [B<sub>12</sub>X<sub>12</sub>]<sup>2</sup><sup>−</sup>. We study the binding of the noble gas atoms He, Ne, Kr, Ar and Xe to [B<sub>12</sub>X<sub>11</sub>]<sup>−</sup> with ligands X = F, Cl, Br, I, CN. While He cannot be captured by these clusters and Ne only binds at low temperatures, the complexes with the heavier Kr, Ar and Xe show appreciable complexation energies and exceed 1 eV at room temperature in the case of [B<sub>12</sub>(CN)<sub>11</sub>Xe]<sup>−</sup>. For the latter three noble gases, we observe a significant charge transfer from the Ng to the icosahedral B<sub>12</sub> cage.

Slip Transition in [001] Oriented Nial at High Temperatures

1990 ◽  
Vol 213 ◽  
Author(s):  
J.T. Kim ◽  
R. Gibala
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
High Temperatures ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Slip Direction ◽  
Annealing Temperatures ◽  
The Stability ◽  
Slip Transition

ABSTRACTThe present work was undertaken to understand the transition in slip direction In [001] oriented NiAl as a function of temperature. Single crystals of [001] NiAl were deformed at room temperature to produce <111> dislocations and were subsequently annealed at various temperatures in order to see the effect of temperature on the stability of the <111> dislocation. These results were compared with corresponding dislocation substructures of specimens deformed directly at high temperatures. During annealing <111> dislocations are dissociated into <001>+<110> dislocations at 773–923 K. It is also observed that <111> dislocations can be dissociated into <001>+<110> dislocations during deformation in the vicinity of the transition temperature of around 773 K. The quantitative details of these changes depend on deformation or annealing temperatures.

Methods for the Concentration of Bovine Ac-Globulin (Factor V)

1961 ◽  
Vol 06 (03) ◽  
pp. 435-444 ◽  
Author(s):  
Ricardo H. Landaburu ◽  
Walter H. Seegers
Keyword(s):  
Room Temperature ◽  
Barium Carbonate ◽  
Deae Cellulose ◽  
Reducing Agents ◽  
Factor V ◽  
Isoelectric Precipitation ◽  
Stabilizing Agent ◽  
Bovine Plasma ◽  
The Stability

SummaryAn attempt was made to obtain Ac-globulin from bovine plasma. The concentrates contain mostly protein, and phosphorus is also present. The stability characteristics vary from one preparation to another, but in general there was no loss before 1 month in a deep freeze or before 1 week in an icebox, or before 5 hours at room temperature. Reducing agents destroy the activity rapidly. S-acetylmercaptosuccinic anhydride is an effective stabilizing agent. Greatest stability was at pH 6.0.In the purification bovine plasma is adsorbed with barium carbonate and diluted 6-fold with water. Protein is removed at pH 6.0 and the Ac-globulin is precipitated at pH 5.0. Rivanol and alcohol fractionation is followed by chromatography on Amberlite IRC-50 or DEAE-cellulose. The final product is obtained by isoelectric precipitation.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

Cholesterol in Serum and Lipoprotein Fractions

1956 ◽  
Vol 2 (3) ◽  
pp. 145-159 ◽  
Author(s):  
Joseph T Anderson ◽  
Ancel Keys
Keyword(s):  
Human Serum ◽  
Total Cholesterol ◽  
Filter Paper ◽  
Room Temperature ◽  
Paper Electrophoresis ◽  
Cholesterol Content ◽  
Intraindividual Variability ◽  
Detailed Data ◽  
The Stability ◽  
Source Of Error

Abstract 1. Methods are described for the separation, by paper electrophoresis and by cold ethanol, of α- and β-lipoproteins in 0.1 ml. of serum, with subsequent analysis of cholesterol in the separated portions. 2. It is shown that both methods of separation yield separated fractions containing substantially the same amounts of cholesterol. 3. Detailed data are given on the errors of measurement for total cholesterol and for cholesterol in the separated lipoprotein fractions. 4. Studies are reported on the stability of cholesterol in stored serum and on paper electrophoresis strips. It is shown that simple drying on filter paper causes no change in cholesterol content and yields a product that is stable for many weeks at ordinary room temperature. 5. The sources of variability in human serum cholesterol values are examined and it is shown that spontaneous intraindividual variability is a much greater source of error than the errors of measurement with these methods.

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