ChemInform Abstract: ELECTROPHILIC HALOGENATION OF OLEFINS. VII. EFFECT OF AN ELECTROPHILE ON THE RESONANCE EFFECT OF α-GROUPS AND CORRELATION OF FREE ACTIVATION ENERGY COMPONENTS OF ADE2 REACTIONS OF ALKENES

The Cope rearrangements of bicyclo[5.1.0]octa-2,5-diene and its 4-hetero-(aza/oxa/phospha) and 4,8-dihetero analogues were investigated using density functional theory at the B3LYP/6–31+G* level in gas phase. The rearrangements of bicyclo[5.1.0]octa-2,5-diene and its symmetrical 4,8-dihetero analogues followed a concerted mechanism involving synchronous transition states. In other cases, although a concerted mechanism was observed, asynchronous transition states were involved. In the case of bicyclo[5.1.0]octa-2,5-diene, a degenerate Cope rearrangement was expected to occur at room temperature (25°C) due to a low free activation energy (ΔG‡ = 14.46 kcal mol–1). However, under similar conditions, the rearrangement of 4,8-dioxabicyclo[5.1.0]octa-2,5-diene was much slower (ΔG‡ = 23.85 kcal mol–1) and the 4,8-diaza- and diphospha analogues did not undergo Cope rearrangement. The Cope rearrangements of 4-phospha-, 8-aza-, 8-aza-4-oxa-, 8-aza-4-phospha-, and 8-oxa-4-phospha-bicyclo[5.1.0]octa-2,5-dienes were exergonic and were expected to occur spontaneously to form the corresponding products. In contrast, rearrangement of 8-oxabicyclo[5.1.0]octa-2,5-diene, though exergonic, was accompanied by a decrease in entropy, due to which Cope rearrangement would occur much more slowly and a mixture of both valence isomers would be formed. The Cope rearrangements of 4-aza-, 4-oxa-, 4-aza-8-oxa-, 8-phospha-, 4-aza-8-phospha-, 4-oxa-8-phospha-, and 4,8-diphospha-bicyclo[5.1.0]octa-2,5-dienes were endergonic; consequently either no Cope rearrangement would take place or it would occur sluggishly.

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Comparison of Conventional and Electron Spectroscopic Imaging in the Fixed Beam Electron Microscope of Ordered Protein Arrays

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117443 ◽

1985 ◽

Vol 43 ◽

pp. 74-75

Author(s):

E. L. Buhle ◽

U. Aebi

Keyword(s):

Image Processing ◽

Electron Microscope ◽

High Resolution ◽

Image Plane ◽

Electron Spectroscopic Imaging ◽

Protein Arrays ◽

Beam Electron ◽

Average Unit ◽

Fixed Beam ◽

Energy Components

CTEM brightfield images are formed by a combination of relatively high resolution elastically scattered electrons and unscattered and inelastically scattered electrons. In the case of electron spectroscopic images (ESI), the inelastically scattered electrons cause a loss of both contrast and spatial resolution in the image. In the case of ESI imaging on the Zeiss EM902, the transmited electrons are dispersed into their various energy components by passing them through a magnetic prism spectrometer; a slit is then placed in the image plane of the prism to select the electrons of a given energy loss for image formation. The purpose of this study was to compare CTEM with ESI images recorded on a Zeiss EM902 of ordered protein arrays. Digital image processing was employed to analyze the average unit cell morphologies of the two types of images.

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Semi-empirical calculation of activation energy for a number of bimolecular reactions. Part I

Journal de Chimie Physique ◽

10.1051/jcp/1971680753 ◽

1971 ◽

Vol 68 ◽

pp. 753-757 ◽

Cited By ~ 1

Author(s):

M.B. Pahari ◽

Rama Basu

Keyword(s):

Activation Energy ◽

Bimolecular Reactions ◽

Semi Empirical

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High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

MRS Proceedings ◽

10.1557/proc-762-a6.8 ◽

2003 ◽

Vol 762 ◽

Cited By ~ 7

Author(s):

A. Gordijn ◽

J.K. Rath ◽

R.E.I. Schropp

Keyword(s):

Activation Energy ◽

High Temperature ◽

High Temperatures ◽

Continuous Wave ◽

Hydrogen Plasma ◽

Silicon Layer ◽

Dark Conductivity ◽

High Deposition Rate ◽

Layer By Layer ◽

Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

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White- and Brown-Rice Supplementation Improves Insulin Tolerance, Brown Fat Activation, Energy Expenditure, and Changes the Gut Microflora in Diet-Induced Obesity

Diabetes ◽

10.2337/db18-1897-p ◽

2018 ◽

Vol 67 (Supplement 1) ◽

pp. 1897-P

Author(s):

HISASHI YOKOMIZO ◽

ATSUSHI ISHIKADO ◽

TAKANORI SHINJO ◽

KYOUNGMIN PARK ◽

YASUTAKA MAEDA ◽

...

Keyword(s):

Activation Energy ◽

Energy Expenditure ◽

Brown Rice ◽

Brown Fat ◽

Gut Microflora ◽

Diet Induced Obesity ◽

Insulin Tolerance

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Activation energy of relaxation processes in chalcogenide glasses

Scientific Herald of Uzhhorod University Series Physics ◽

10.24144/2415-8038.2013.34.59-63 ◽

2013 ◽

Vol 34 (0) ◽

pp. 59-63

Author(s):

А. А. Горват ◽

В. М. Кришеник ◽

А. Е. Кріштофорій ◽

В. В. Мінькович ◽

О. А. Молнар

Keyword(s):

Activation Energy ◽

Chalcogenide Glasses ◽

Relaxation Processes

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Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v8i3.1496 ◽

2015 ◽

Vol 8 (3) ◽

pp. 2176-2188 ◽

Cited By ~ 4

Author(s):

Keisham Nanao Singh

Keyword(s):

Activation Energy ◽

Silver Nanoparticles ◽

Liquid Crystal ◽

Dielectric Relaxation ◽

Relaxation Process ◽

Relaxation Times ◽

Low Frequency ◽

Bulk Liquid ◽

Molecular Rearrangement ◽

Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

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