Mass spectrometric-Knudsen cell study of cerium dicrbide sublimation and thermal and x-ray analyses of cerium dicarbide

1967 ◽  
Vol 71 (13) ◽  
pp. 4476-4479 ◽  
Author(s):  
Perrin Winchell ◽  
N. L. Baldwin
Keyword(s):  
Mass Spectrometric ◽  
Knudsen Cell ◽  
X Ray ◽  
Cell Study

Mass spectrometric-Knudsen cell study of the gaseous oxides of platinum

1967 ◽  
Vol 71 (11) ◽  
pp. 3686-3689 ◽  
Author(s):  
John H. Norman ◽  
H. Gene Staley ◽  
Wayne Elliot Bell
Keyword(s):  
Mass Spectrometric ◽  
Knudsen Cell ◽  
Cell Study

Resolution of a protein sequence ambiguity by X-ray crystallographic and mass spectrometric methods

1992 ◽  
Vol 25 (2) ◽  
pp. 205-210 ◽  
Author(s):  
L. J. Keefe ◽  
E. E. Lattman ◽  
C. Wolkow ◽  
A. Woods ◽  
M. Chevrier ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Electron Density ◽  
Mass Spectrometric ◽  
Amino Acid Sequences ◽  
Data Matrix ◽  
Protein Crystal ◽  
Insertion Mutant ◽  
Laser Desorption Mass Spectrometry ◽  
X Ray

Ambiguities in amino acid sequences are a potential problem in X-ray crystallographic studies of proteins. Amino acid side chains often cannot be reliably identified from the electron density. Many protein crystal structures that are now being solved are simple variants of a known wild-type structure. Thus, cloning artifacts or other untoward events can readily lead to cases in which the proposed sequence is not correct. An example is presented showing that mass spectrometry provides an excellent tool for analyzing suspected errors. The X-ray crystal structure of an insertion mutant of Staphylococcal nuclease has been solved to 1.67 Å resolution and refined to a crystallographic R value of 0.170 [Keefe & Lattman (1992). In preparation]. A single residue has been inserted in the C-terminal α helix. The inserted amino acid was believed to be an alanine residue, but the final electron density maps strongly indicated that a glycine had been inserted instead. To confirm the observations from the X-ray data, matrix-assisted laser desorption mass spectrometry was employed to verify the glycine insertion. This mass spectrometric technique has sufficient mass accuracy to detect the methyl group that distinguishes glycine from alanine and can be extended to the more common situation in which crystallographic measurements suggest a problem with the sequence, but cannot pinpoint its location or nature.

Mass spectrometric study of the leak tightness of products made of technical sintered beryllium

2021 ◽  
Vol 87 (4) ◽  
pp. 26-31
Author(s):  
A. N. Fokanov ◽  
V. F. Podurazhnaya ◽  
A. V. Tebyakin
Keyword(s):  
Raw Materials ◽  
Flaw Detection ◽  
Mass Spectrometric Study ◽  
Radiation Energy ◽  
Radiation Detectors ◽  
Mass Spectrometric ◽  
High Tech ◽  
Vacuum Equipment ◽  
X Ray ◽  
Leak Tightness

Beryllium products exhibiting a low level of absorption of the radiation energy are widely used in scientific instrumentation design (x-ray technology, radiation detectors, etc.). We present the results of studying the leak tightness of products (disks, plates) made of technical sintered beryllium of standard purity and foil obtained by «warm» rolling from high-purity beryllium. The relevant standards and requirements for testing are given. The leak tightness control was performed using mass spectrometric helium leak detectors with forevacuum backing pumps (oil and dry diaphragm pumps) and specialized vacuum equipment. The parameters of tightness of samples made of technical sintered beryllium were determined. The level of the helium signal during blowing was (0.6 – 7.4) × 10–11 Pa · m3/sec, which corresponds to the tightness standard of foreign analogues and matches the requirements of domestic manufacturers of x-ray equipment. The data spread tended to increase due to the growth of the background value. The obtained results can be used to improve high-tech equipment intended for flaw detection, medical devices, rapid analysis of ore raw materials, radiation safety equipment, etc.

scholarly journals Knudsen Cell Mass Spectrometric Study of the Thermodynamic Properties of Fe-W Alloys

1984 ◽  
Vol 70 (6) ◽  
pp. 549-556 ◽  
Author(s):  
Yoshiyuki UESHIMA ◽  
Hisashi YAMANA ◽  
Toyoko SUGIYAMA ◽  
Eiji ICHISE
Keyword(s):  
Thermodynamic Properties ◽  
Cell Mass ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Knudsen Cell ◽  
Spectrometric Study
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