Structural and chemical modifications of oxides and OH generation by space weathering: Electron microscopic/spectroscopic study of hydrogen-ion-irradiated Al2O3

2021 ◽  
Author(s):  
Yohei Igami ◽  
Shunsuke Muto ◽  
Aki Takigawa ◽  
Masahiro Ohtsuka ◽  
Akira Miyake ◽  
...  
Keyword(s):  
Spectroscopic Study ◽  
Hydrogen Ion ◽  
Space Weathering ◽  
Chemical Modifications ◽  
Electron Microscopic

scholarly journals ACTION OF TRITON X-100 ON CHLOROPLAST MEMBRANES

1967 ◽  
Vol 33 (2) ◽  
pp. 395-410 ◽  
Author(s):  
David W. Deamer ◽  
Antony Crofts
Keyword(s):  
Ion Transport ◽  
Conformational Changes ◽  
Active Material ◽  
Active Species ◽  
Hydrogen Ion ◽  
Electron Microscopic ◽  
Chloroplast Membranes ◽  
Ionic Equilibrium ◽  
Hydrogen Ion Transport ◽  
Triton X

Addition of Triton X-100 to chloroplast suspensions to a final concentration of 100–200 µM causes an approximate tripling of chloroplast volume and complete inhibition of light-induced conformational changes, light-dependent hydrogen ion transport, and photophosphorylation. Electron microscopic studies show that chloroplasts treated in this manner manifest extensive swelling in the form of vesicles within their inner membrane structure. Triton was adsorbed to chloroplast membranes in a manner suggesting a partition between the membrane phase and the suspending medium, rather than a strong, irreversible binding. This adsorption results in the production of pores through which ions may freely pass, and it is suggested that the inhibition of conformational changes, hydrogen ion transport, and photophosphorylation by Triton is due to an inability of treated chloroplast membranes to maintain a light-dependent pH gradient. The observed swelling is due to water influx in response to a fixed, osmotically active species within the chloroplasts, after ionic equilibrium has occurred. This is supported by the fact that chloroplasts will shrink upon Triton addition if a nonpenetrating, osmotically active material such as dextran or polyvinylpyrrolidone is present externally in sufficient concentration (>0.1 mM) to offset the osmotic activity of the internal species.

scholarly journals Light and Electron Microscopic Evaluation of Hydrogen Ion-Induced Brain Necrosis

1987 ◽  
Vol 7 (5) ◽  
pp. 625-632 ◽  
Author(s):  
C. K. Petito ◽  
R. P. Kraig ◽  
W. A. Pulsinelli
Keyword(s):  
Structural Changes ◽  
Vascular Occlusion ◽  
Hydrogen Ion ◽  
Solution Ph ◽  
Electron Microscopic ◽  
Neuronal Necrosis ◽  
Ischemic Brain ◽  
Microscopic Evaluation ◽  
Neuronal Swelling ◽  
Excessive Accumulation

Excessive accumulation of hydrogen ions in the brain may play a pivotal role in initiating the necrosis seen in infarction and following hyperglycemic augmentation of ischemic brain damage. To examine possible mechanisms involved in hydrogen ion-induced necrosis, sequential structural changes in rat brain were examined following intracortical injection of sodium lactate solution (pH 4.5), as compared with injections at pH 7.3. Following pH 7.3 injection, neuronal swelling developed between 1 and 6 h, but only a needle track wound surrounded by a thin rim of necrotic neurons and vacuolated neuropil was present 24 h after injection. In contrast, pH 4.5 injection produced neuronal necrosis as soon as 1 h after injection, followed by necrosis of astrocytes and intravascular thrombi at 3 and 6 h. Alterations common to both groups included vascular permeability to horseradish peroxidase, dilation of extracellular spaces, astrocyte swelling, capillary compression, and vascular stasis. These data suggest that neurons, astrocytes, and endothelia can be directly damaged by increased acid in the interstitial space. Lethal injury initially appeared to affect neurons, while subsequent astrocyte necrosis and vascular occlusion may damage tissue by secondary ischemia.

Correlation between CdS photoanodic behaviour and electrode chemical modifications: An X-ray photoelectron spectroscopic study

1985 ◽  
Vol 7 (4) ◽  
pp. 163-168 ◽  
Author(s):  
J. Riga ◽  
J. J. Verbist ◽  
P. Josseaux ◽  
A. Kirsch-de Mesmaeker
Keyword(s):  
Spectroscopic Study ◽  
Chemical Modifications ◽  
X Ray

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

Sign in / Sign up

Export Citation Format

Share Document