Close contact distance between hexacyanometallate ions in the course of electron transfer

1999 ◽  
Vol 9 (5) ◽  
pp. 181-182 ◽  
Author(s):  
Vitalii Yu. Kotov ◽  
Galina A. Tsirlina
Keyword(s):  
Electron Transfer ◽  
Close Contact ◽  
Contact Distance

scholarly journals The susceptibility of disulfide bonds towards radiation damage may be explained by S...O interactions

IUCrJ ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 825-834
Author(s):  
Rajasri Bhattacharyya ◽  
Jesmita Dhar ◽  
Shubhra Ghosh Dastidar ◽  
Pinak Chakrabarti ◽  
Manfred S. Weiss
Keyword(s):  
Electron Transfer ◽  
Disulfide Bond ◽  
Disulfide Bonds ◽  
Metal Ion ◽  
Structural Information ◽  
Close Contact ◽  
Bond Cleavage ◽  
Protein Structures ◽  
Protein Crystal ◽  
X Ray

Radiation-induced damage to protein crystals during X-ray diffraction data collection is a major impediment to obtaining accurate structural information on macromolecules. Some of the specific impairments that are inflicted upon highly brilliant X-ray irradiation are metal-ion reduction, disulfide-bond cleavage and a loss of the integrity of the carboxyl groups of acidic residues. With respect to disulfide-bond reduction, previous results have indicated that not all disulfide bridges are equally susceptible to damage. A careful analysis of the chemical environment of disulfide bonds in the structures of elastase, lysozyme, acetylcholinesterase and other proteins suggests that S—S bonds which engage in a close contact with a carbonyl O atom along the extension of the S—S bond vector are more susceptible to reduction than the others. Such an arrangement predisposes electron transfer to occur from the O atom to the disulfide bond, leading to its reduction. The interaction between a nucleophile and an electrophile, akin to hydrogen bonding, stabilizes protein structures, but it also provides a pathway of electron transfer to the S—S bond, leading to its reduction during exposure of the protein crystal to an intense X-ray beam. An otherwise stabilizing interaction can thus be the cause of destabilization under the condition of radiation exposure.

Adjustable anchoring of Ni/Co cations by oxygen-containing functional groups on functionalized graphite paper and accelerated mass/electron transfer for overall water splitting

2020 ◽  
Vol 10 (8) ◽  
pp. 2627-2643 ◽  
Author(s):  
Yiyi Huang ◽  
Lei Sun ◽  
Zebin Yu ◽  
Ronghua Jiang ◽  
Jun Huang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Water Splitting ◽  
Functional Groups ◽  
Cellular Network ◽  
Close Contact ◽  
Overall Water Splitting ◽  
Porous Nanosheets ◽  
Electron Transportation

NCS–NCO/FGP0.44 with a cellular network of porous nanosheets and close-contact heterointerface reveals accelerated interfacial mass/electron transportation for overall water splitting.

scholarly journals Model of electric charge distribution in the trap of a close-contact TENG system

Open Physics ◽  
2020 ◽  
Vol 18 (1) ◽  
pp. 1-5
Author(s):  
SeongMin Kim
Keyword(s):  
State Energy ◽  
Sliding Mode ◽  
Close Contact ◽  
Rebound Effect ◽  
Triboelectric Nanogenerator ◽  
Continuous Contact ◽  
Large Size ◽  
Contact Distance ◽  
Electron Propagation ◽  
Electric Charge Distribution

AbstractElectron propagation in a trapped state between an insulator and a metal during very close contact in a triboelectric nanogenerator (TENG) system was considered in this study. A single energy level (E0) was assumed for the trap and wave function inside the trap, which is related to the ground state energy. The phase of the waveform in the metal (neglecting the rebound effect at the wall) was assumed very small (δ′ ≪ 1) because of the large size of the metal. The contact distance between the trap and metal is very small, which allows us to ignore the vacuum potential. Based on our results, the probability of finding an electron inside the trap as a function of time was found to be in oscillation (i.e., back-and-forth propagation of the electron between the trap and metal leads to an equilibrium state). These results can be used to understand the quantum mechanisms of continuous contact, particularly in sliding-mode TENG systems.

The porphyrin-C60 non-bonded interaction: an ab initio MO and DFT study

2002 ◽  
Vol 06 (12) ◽  
pp. 783-794 ◽  
Author(s):  
Michael J. Shephard ◽  
Michael N. Paddon-Row
Keyword(s):  
Density Functional ◽  
Close Contact ◽  
Photophysical Properties ◽  
Cost Effective ◽  
Theoretical Models ◽  
Dft Methods ◽  
Hartree Fock ◽  
Best Estimate ◽  
Contact Distance ◽  
Moller Plesset

The non-bonded interactions between a porphyrin molecule and a C 60 molecule, in the gas-phase, has been systematically investigated using various theoretical models. These are: (1) wavefunction-based methods, Hartree-Fock SCF (HF), second-order Møller-Plesset (MP2) theory, and the localized MP2 (LMP2) theory using the diatomics in molecules (DIM-LMP2) and triatomics in molecules (TRIM-LMP2) methods; (2) density functional theory (DFT), using non-local (BLYP, PW91), hybrid (B3LYP), and local (SVWN) functionals. Of the HF and DFT methods examined, corrected for BSSE using the counterpoise (CP) method, only the SVWN method predicts a close separation (2.5 Å) between the porphyrin and the C 60 molecules, in line with close contacts observed in crystal structures of cocrystallates of porphyrins and fullerenes (2.7-3.0 Å). The MP2 and LMP2 methods also predict a close contact between the two molecules although the MP2 and TRIM-LMP2 methods overestimate the interaction giving a separation < 2.5 Å while the DIM-LMP2 method gives a satisfactory separation of 2.9 Å. The SVWN and DIM-LMP2 methods also predict a reasonable complexation energy of ca. −13 kcal/mol (SVWN and DIM-LMP2 CP-uncorrected) and −7.9 kcal/mol (SVWN CP-corrected), whereas the MP2 and TRIM-LMP2 methods probably strongly overestimate the complexation energy. The remaining methods underestimate the complexation energy. The CP-uncorrected DIM-LMP2/6-31G(d) method gave the best estimate of the porphyrin- C 60 separation (2.9 Å) with a complexation energy of −13.3 kcal/mol; however, the more cost-effective SVWN functional gives satisfactory values for these quantities with the SVWN/6-311+G(d) level providing the best estimate for the complexation energy (−16.5 kcal/mol). The porphyrin- C 60 interaction was investigated in the giant triad 1 in which a zinc porphyrin, a dimethoxynaphthalene and a C 60 fullerene are separated by two norbornylogous bridge sections of six and five bond lengths, respectively. All methods predict the existence of a compact form of the molecule in which the porphyrin and C 60 moieties are only 2.9-4.3 Å apart (contact distance). This finding is consistent with certain photophysical properties of 1.

Ultrastructure of Liver in Lactosyl Ceramidosis

1971 ◽  
Vol 29 ◽  
pp. 312-313
Author(s):  
Z. Hruban ◽  
J. R. Esterly ◽  
G. Dawson ◽  
A. O. Stein
Keyword(s):  
Connective Tissue ◽  
Liver Biopsy ◽  
Osmium Tetroxide ◽  
Close Contact ◽  
Multivesicular Bodies ◽  
Bile Canaliculi ◽  
Dense Bodies ◽  
Marginal Plates ◽  
Membranous Material ◽  
Perichromatin Granules

Samples of a surgical liver biopsy from a patient with lactosyl ceramidosis were fixed in paraformaldehyde and postfixed in osmium tetroxide. Hepatocytes (Figs. 1, 2) contained 0.4 to 2.1 μ inclusions (LCI) limited by a single membrane containing lucid matrix and short segments of curved, lamellated and circular membranous material (Fig. 3). Numerous LCI in large connective tissue cells were up to 11 μ in diameter (Fig. 2). Heterogeneous dense bodies (“lysosomes”) were few and irregularly distributed. Rough cisternae were dilated and contained smooth vesicles and surface invaginations. Close contact with mitochondria was rare. Stacks were small and rare. Vesicular rough reticulum and glycogen rosettes were abundant. Smooth vesicular reticulum was moderately abundant. Mitochondria were round with few cristae and rare matrical granules. Golgi complex was seen rarely (Fig. 1). Microbodies with marginal plates were usual. Multivesicular bodies were very rare. Neutral lipid was rare. Nucleoli were small and perichromatin granules were large. Small bile canaliculi had few microvilli (Fig. 1).

A light optical diffractometer for electron microscopical images operating in line

1978 ◽  
Vol 36 (1) ◽  
pp. 86-87
Author(s):  
P. Bonhomme ◽  
A. Beorchia
Keyword(s):  
Electron Microscopy ◽  
Electron Transfer ◽  
Electron Microscope ◽  
Image Converter ◽  
Coherent Light ◽  
Spatial Filters ◽  
Electron Image ◽  
Electron Microscopical ◽  
Working Parameters ◽  
Amorphous Part

We have already described (1.2.3) a device using a pockel's effect light valve as a microscopical electron image converter. This converter can be read out with incoherent or coherent light. In the last case we can set in line with the converter an optical diffractometer. Now, electron microscopy developments have pointed out different advantages of diffractometry. Indeed diffractogram of an image of a thin amorphous part of a specimen gives information about electron transfer function and a single look at a diffractogram informs on focus, drift, residual astigmatism, and after standardizing, on periods resolved (4.5.6). These informations are obvious from diffractogram but are usualy obtained from a micrograph, so that a correction of electron microscope parameters cannot be realized before recording the micrograph. Diffractometer allows also processing of images by setting spatial filters in diffractogram plane (7) or by reconstruction of Fraunhofer image (8). Using Electrotitus read out with coherent light and fitted to a diffractometer; all these possibilities may be realized in pseudoreal time, so that working parameters may be optimally adjusted before recording a micrograph or before processing an image.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

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