Effect of Divalent Cations on the Coagulation of F Centers in Potassium Chloride

1959 ◽  
Vol 30 (1) ◽  
pp. 342-343 ◽  
Author(s):  
L. Richard Watson ◽  
Allen B. Scott
Keyword(s):  
Potassium Chloride ◽  
Divalent Cations ◽  
F Centers

Diffusion of F-centers in potassium chloride crystals

1972 ◽  
Vol 50 (1) ◽  
pp. 367-377 ◽  
Author(s):  
G. C. Kuczynski ◽  
J. J. Byun
Keyword(s):  
Potassium Chloride ◽  
F Centers

Chemistry with F Centers: Reduction of Organic Molecules on the Defective Potassium Chloride(100) Surface

2020 ◽  
Vol 124 (23) ◽  
pp. 12606-12616 ◽  
Author(s):  
Michael Häfner ◽  
Manuel Hochheim ◽  
Thomas Bredow
Keyword(s):  
Potassium Chloride ◽  
Organic Molecules ◽  
F Centers

Optical stability of F centers in potassium chloride ?cleavage? and ordinary whiskers

1976 ◽  
Vol 19 (1) ◽  
pp. 107-110
Author(s):  
I. Ya. Melik-Gaikazyan ◽  
A. N. Kravets ◽  
A. A. Zhaksylykova
Keyword(s):  
Potassium Chloride ◽  
Optical Stability ◽  
F Centers

Ionic conductivity of potassium chloride crystals

1970 ◽  
Vol 48 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Suresh Chandra ◽  
John Rolfe
Keyword(s):  
Potassium Chloride ◽  
Defect Formation ◽  
Divalent Cations ◽  
Formation Enthalpy ◽  
Negative Ion ◽  
Strontium Chloride ◽  
Coulomb Interactions ◽  
Vacancy Migration ◽  
Positive Ion ◽  
Migration Enthalpy

The electrical conductivity of single crystals of potassium chloride was measured as a function of temperature, and as a function of the amount of strontium chloride or potassium carbonate impurity. The results were analyzed by using a least-squares curve-fitting computer program in which the basic assumption was that conductivity was due entirely to the motion of separated anion and cation vacancies (Schottky defects). Coulomb interactions between charged defects were allowed for by using Debye–Hückel theory. With the exception of the conductivity of pure crystals very near the melting point, experimental conductivity measurements agreed with values calculated from the following parameters: Schottky-defect formation enthalpy hs = 2.59 eV, entropy ss = 9.61k; positive ion vacancy migration enthalpy Δh1 = 0.73 eV, entropy Δs1 = 2.70k; negative ion vacancy migration enthalpy Δh2 = 0.99 eV, entropy Δs2 = 4.14k; association of divalent cations and positive ion vacancies enthalpy χ = 0.58 eV, entropy η = 1.30k.

Ultrastructural Localization of Acid Mucosubstance in Skeletal Muscle

1967 ◽  
Vol 25 ◽  
pp. 52-53 ◽  
Author(s):  
William J. Dougherty ◽  
Samuel S. Spicer
Keyword(s):  
Striated Muscle ◽  
Divalent Cations ◽  
Ultrastructural Localization ◽  
Major Elements ◽  
Frozen Sections ◽  
Thorium Dioxide ◽  
Iron Solution ◽  
Coupling System ◽  
Psoas Muscles ◽  
Formalin Fixed

In recent years, considerable attention has focused on the morphological nature of the excitation-contraction coupling system of striated muscle. Since the study of Porter and Palade, it has become evident that the sarcoplastic reticulum (SR) and transverse tubules constitute the major elements of this system. The problem still exists, however, of determining the mechamisms by which the signal to interdigitate is presented to the thick and thin myofilaments. This problem appears to center on the movement of Ca++ions between myofilaments and SR. Recently, Philpott and Goldstein reported acid mucosubstance associated with the SR of fish branchial muscle using the colloidal thorium dioxide technique, and suggested that this material may serve to bind or release divalent cations such as Ca++. In the present study, Hale's iron solution adapted to electron microscopy was applied to formalin-fixed myofibrils isolated from glycerol-extracted rabbit psoas muscles and to frozen sections of formalin-fixed rat psoas muscles.

Structure, assembly and interactions of the nuclear lamina and the nuclear pore complex

1992 ◽  
Vol 50 (1) ◽  
pp. 490-491
Author(s):  
N. Panté ◽  
M. Jarnik ◽  
E. Heitlinger ◽  
U. Aebi
Keyword(s):  
Nuclear Pore Complex ◽  
Divalent Cations ◽  
Nuclear Lamina ◽  
Dynamic Structure ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Cytoplasmic Filaments ◽  
Radial Spokes ◽  
Nuclear Ring ◽  
Central Plug

The nuclear pore complex (NPC) is a ∼120 MD supramolecular machine implicated in nucleocytoplasmic transport, that is embedded in the double-membraned nuclear envelope (NE). The basic framework of the ∼120 nm diameter NPC consists of a 32 MD cytoplasmic ring, a 66 MD ‘plug-spoke’ assembly, and a 21 MD nuclear ring. The ‘central plug’ seen in en face views of the NPC reveals a rather variable appearance indicating that it is a dynamic structure. Projecting from the cytoplasmic ring are 8 short, twisted filaments (Fig. 1a), whereas the nuclear ring is topped with a ‘fishtrap’ made of 8 thin filaments that join distally to form a fragile, 30-50 nm distal diameter ring centered above the NPC proper (Fig. 1b). While the cytoplasmic filaments are sensitive to proteases, they as well as the nuclear fishtraps are resistant to RNase treatment. Removal of divalent cations destabilizes the distal rings and thereby opens the fishtraps, addition causes them to reform. Protruding from the tips of the radial spokes into perinuclear space are ‘knobs’ that might represent the large lumenal domain of gp210, a membrane-spanning glycoprotein (Fig. 1c) which, in turn, may play a topogenic role in membrane folding and/or act as a membrane-anchoring site for the NPC. The lectin wheat germ agglutinin (WGA) which is known to recognize the ‘nucleoporins’, a family of glycoproteins having O-linked N-acetyl-glucosamine, is found in two locations on the NPC (Fig. 1. d-f): (i) whereas the cytoplasmic filaments appear unlabelled (Fig. 1d&e), WGA-gold labels sites between the central plug and the cytoplasmic ring (Fig. le; i.e., at a radius of 25-35 nm), and (ii) it decorates the distal ring of the nuclear fishtraps (Fig. 1, d&f; arrowheads).

Effects of Mg2+ on Chromatic Structure in Isolated Chicken Liver Nuclei

1990 ◽  
Vol 48 (3) ◽  
pp. 130-131
Author(s):  
Soichiro Arai ◽  
Yuh H. Nakanishi
Keyword(s):  
Chromatin Structure ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Divalent Cations ◽  
Chromatin Condensation ◽  
Chicken Liver ◽  
Electron Microscopic ◽  
Razor Blade ◽  
Microscopic Studies ◽  
Liver Nuclei

Although many electron microscopic studies on extracted chromatin have provided considerable information on chromatin condensation induced by divalent cations, there is only a little literature available on the effects of divalent cations on chromatin structure in intact nuclei. In the present study, the effects of Mg2+ on chromatin structure in isolated chicken liver nuclei were examined over a wide concentration range of Mg2+ by scanning electron microscopy.Nuclei were prepared from chicken liver by the method of Chauveau et al. with some modifications. The nuclei were suspended in 25 mM triethanolamine chloride buffer (pH7.4) with 1 mM EDTA or in the buffer with concentrations of MgCl2 varying from 1 to 50 mM. After incubation for 1 min at 0°C, glutaraldehyde was added to 1.8% and the nuclei were fixed for 1 h at 4°C. The fixed nuclei were mixed with 15% gelatin solution warmed at about 40°C, and kept at room temperature until the mixture set. The gelatin containing the nuclei was fixed with 2% glutaraldehyde for 2-4 h, and cut into small blocks. The gelatin blocks were conductive-stained with 2% tannic acid and 2% osmium tetroxide, dehydrated in a graded series of ethanol, and freeze-cracked with a razor blade in liquid nitrogen.

Sign in / Sign up

Export Citation Format

Share Document