scholarly journals The Effect of Clustering on the Measurement of the Mobility of Potassium Ions in Nitrogen Gas

1972 ◽  
Vol 25 (4) ◽  
pp. 465 ◽  
Author(s):  
EW McDaniel

McDaniel and Martin (1971) have suggested that the zero-field reduced mobility of (unclustered) K+ ions in nitrogen at room temperature and low pressures (~ 0�1 torr) is accurately enough known to be useful in pressure calibration of drift tubes and other types of apparatus employed in atomic collision experiments, where the uncertainty in the value of the gas pressure frequently represents the largest source of error in the measurements. Elford (1971) has questioned the validity of this suggestion on the grounds that he has observed a very slight, explicit dependence of the reduced mobility of K+ ions on the gas pressure in drift tube experiments with nitrogen and other gases. Although this pressure effect cannot be reconciled with existing mobility theory (McDaniel and Mason 1972), Elford believes the effect to be real and hence maintains that in fact the true mobility of unclustered K+ ions in nitrogen is not accurately known. The purpose of this communication is to point out that Elford's experiments with nitrogen were conducted at pressures sufficiently high that significant clustering of nitrogen molecules with his K+ ions inevitably occurred and that consequently the suggestion of McDaniel and Martin (1971) is not weakened by his findings.

1974 ◽  
Vol 27 (2) ◽  
pp. 227 ◽  
Author(s):  
RO Watts

Recent work on the mobilities of alkali metal ions in the noble gases has indicated that there is a pressure dependence of the zero-field reduced mobility. The possibility of temporarily bound dimmers being responsible for this pressure dependence is examined here by quantum mechanical methods for the case of potassium ions in argon and it is shown that the conditions needed for a small pressure dependence do exist at room temperature.


1956 ◽  
Vol 2 (3) ◽  
pp. 145-159 ◽  
Author(s):  
Joseph T Anderson ◽  
Ancel Keys

Abstract 1. Methods are described for the separation, by paper electrophoresis and by cold ethanol, of α- and β-lipoproteins in 0.1 ml. of serum, with subsequent analysis of cholesterol in the separated portions. 2. It is shown that both methods of separation yield separated fractions containing substantially the same amounts of cholesterol. 3. Detailed data are given on the errors of measurement for total cholesterol and for cholesterol in the separated lipoprotein fractions. 4. Studies are reported on the stability of cholesterol in stored serum and on paper electrophoresis strips. It is shown that simple drying on filter paper causes no change in cholesterol content and yields a product that is stable for many weeks at ordinary room temperature. 5. The sources of variability in human serum cholesterol values are examined and it is shown that spontaneous intraindividual variability is a much greater source of error than the errors of measurement with these methods.


1987 ◽  
Vol 38 (6) ◽  
pp. 228-233
Author(s):  
Saburou KUWANO ◽  
Masahiro SUGIYAMA ◽  
Yoshio SHIBUYA ◽  
Terunori OOTAKE ◽  
Takeo OKI

2006 ◽  
Vol 61 (5-6) ◽  
pp. 289-292 ◽  
Author(s):  
Hong-Gang Liu ◽  
Xiao-Xuan Wu ◽  
Wen-Chen Zheng ◽  
Lv He

The EPR zero-field splitting D (= b02 ) and its pressure and temperature dependence for trigonal Mn2+ centers in low and room temperature phases in [Zn(H2O)6](BF4)2 :Mn2+ crystal are studied by a high-order perturbation formula based on the dominant spin-orbit coupling mechanism. From the studies, the local trigonal distortion angles, the local angular compressibilities and the local angular thermal expansion coefficients for Mn2+ centers in both phases of the [Zn(H2O)6](BF4)2 crystal are estimated. The results are discussed


1966 ◽  
Vol 39 (2) ◽  
pp. 211-216
Author(s):  
B. A. Hunter ◽  
M. J. Kleinfeld

Abstract A novel method for producing a cellular cured rubber product at room temperature has been developed. Pourable liquid polysulfide polymers are treated with a conventional oxidizing curative and selected water-sensitive or oxidation-sensitive blowing agents. Standing at ambient temperature the viscous liquid mixture gradually “rises” and cures to form a finely porous cellular rubber product. Conventional curatives employed include oxidizing agents such as lead peroxide and cumene hydroperoxide. These convert terminal or pendant thiol groups in the polysulfide polymer chains to chain-connecting disulfide linkages. Water is a byproduct of the curing reaction. In the presence of water-sensitive blowing agents such as, (1) metal salts of azodicarboxylic acid or, (2) metal hydride compounds the water produced in the cure reacts to form copious amounts of nitrogen or of hydrogen. Alternatively, oxidation-sensitive blowing agents such as p, p′-oxybis-(benzene sulfonyl hydrazide) react directly with the oxidizing curative to form nitrogen gas. The blowing reactions are concurrent with cure and efficient and controllable expansion can be achieved. The unique process offers possible economies and special properties in applications of liquid polysulfide rubbers as potting compounds, joint sealants, solvent resistant forms, and cold casting compounds.


Research on the catalysis by metals of the combination of hydrogen and oxygen at low pressures was commenced in these laboratories by Cooper in 1923. Investigating the catalytic properties of a short platinum filament subjected to various pre-treatments by heating it electrically in hydrogen or oxygen or in vacuo , he found that the metallic surface thus cleaned became so active at room temperature as to render the quantitative measurement of the catalysed reaction impossible. It was discovered also that mercury vapour is a very potent poison of the surface, the enormously active clean platinum surface being rendered completely inactive by exposure to mercury vapour for a few minutes: a fact noted but apparently insufficiently emphasized in a paper published by Chapman and Hall in 1929. Owing to the difficulties involved in wording with a catalyst of such high activity, the research was discontinued in favour of an investigation of the same reaction using silver instead of platinum, a clean surface of this metal having been found to catalyse the reaction at a convenient rate at room temperature. The following facts were established:— (1) At the temperature of the laboratory a surface of metallic silver adsorbs completely a quantity of gaseous oxygen sufficient to form a complete unimolecular layer of silver oxide. This adsorbed oxygen cannot, of course, be removed by evacuation.


2012 ◽  
Vol 1444 ◽  
Author(s):  
Robert M. Harker ◽  
Afiya H. Chohollo

ABSTRACTIdentical samples of uranium coupons were prepared and each exposed to hydrogen for different times (where this time is significantly less than a classically understood ‘induction time’). Samples were prepared from rolled depleted uranium stock: as-received oxide was removed on all surfaces and two faces (~12x12 mm) were polished to a sub-micron standard. Samples were individually taken through a Vacuum Thermal Pre-Treatment cycle from room temperature to 200°C to the reaction temperature (80°C) over 40 hours and subsequently exposed to 10 mbar O2 for 24 hours. After O2 was removed, the samples were exposed to hydrogen for pre-determined times of up to 48 minutes. Examination of the samples by Scanning Electron Microscopy (SEM) has, as expected, identified small features protruding from the surface believed to have been caused by sub-surface precipitation of UH3. In general these features are circular and isolated from each other, have a diameter of less than 3μm and appear as either ‘flat-topped’ or ‘domed’ morphology. In addition, longer time exposure samples show a predominance of ‘area attack’ where coalesced sub-surface precipitation appears to be confined to particular metal grains. X-Ray Diffraction (XRD) data show an increase in the quantity of UH3 with time.


2020 ◽  
Vol 127 (22) ◽  
pp. 223901 ◽  
Author(s):  
Mangyuan Ma ◽  
Calvin Ching Ian Ang ◽  
Yong Li ◽  
Zizhao Pan ◽  
Weiliang Gan ◽  
...  

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