THE VAPOR DENSITY OF HYDROGEN SULPHIDE

1931 ◽  
Vol 5 (4) ◽  
pp. 442-447 ◽  
Author(s):  
R. H. Wright ◽  
O. Maass
Keyword(s):  
Hydrogen Sulphide ◽  
Vapor Density ◽  
Molecular Weights ◽  
Gas Laws ◽  
Standard Pressure ◽  
The Difference ◽  
Molecular Attraction

An apparatus for the measurement of the vapor density of condensable gases at pressures greater than atmospheric and at various temperatures is described. The vapor density of redistilled hydrogen sulphide was measured at 47°, 25°, 0°, −20°, and −35 °C., and up to 4 atm. pressure. The interpolated value for the vapor density of hydrogen sulphide under standard conditions was found to be 1.537. This value agrees with the values given by Leduc (1.538) and Baume and Perrot (1.539), but the difference may be attributed in part to the neglect of the earlier experimenters to allow for deviations from the gas laws in correcting their values to standard pressure. The results are expressed as apparent molecular weights, and the deviations from the theoretical value shown to be due to the action of molecular attraction.

Characterization of the surface of hydrodesulphurization catalysts by adsorption of hydrocarbons

1984 ◽  
Vol 49 (2) ◽  
pp. 410-420
Author(s):  
Eva Hillerová ◽  
Miroslav Zdražil
Keyword(s):  
Hydrogen Sulphide ◽  
Chromatographic Method ◽  
Supported Catalysts ◽  
Alumina Surface ◽  
Reversible Adsorption ◽  
The Difference

Reversible adsorption of heptane and benzene on model and industrial hydrodesulphurization molybdena catalysts has been studied by elution chromatographic method at 150 °C. An increase in the adsorption of heptane on sulphidation of adsorbents was small for Al2O3 and great for MoO3. Supported catalysts behaved as mixture of Al2O3 and MoO3.The portion of surface which can be transformed by sulphidation into MoS2 ranged from 0 to 65% for individual commercial catalysts, as determined from the change in heptane adsorption after sulphidation of a given sample. The polarity of catalysts, including their acidity, was estimated from the difference between adsorption of benzene and heptane. The polarity of model and industrial catalysts in oxidic form was similar to that of alumina in most cases. The decrease in the polarity after sulphidation of the adsorbents was small for Al2O3 and great for MoO3. The decrease in polarity resulting from sulphidation of supported catalysts was relatively small, since the reaction of MoO3 monolayer with hydrogen sulphide leads to partial reformation of the alumina surface. The acidity of supported sulphided hydrodesulphurization catalysts has been shown by this method to be comparable with the acidity of the support itself.

scholarly journals Effects of oat bran, processed to different molecular weights of β-glucan, on plasma lipids and caecal formation of SCFA in mice

2010 ◽  
Vol 104 (3) ◽  
pp. 364-373 ◽  
Author(s):  
Tina Immerstrand ◽  
Kristina E. Andersson ◽  
Caroline Wange ◽  
Ana Rascon ◽  
Per Hellstrand ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Propionic Acid ◽  
Plasma Lipids ◽  
Plasma Cholesterol ◽  
Control Diet ◽  
Cholesterol Lowering ◽  
Molecular Weights ◽  
Oat Bran ◽  
Diet Pattern ◽  
The Difference

In the present study, we evaluated the cholesterol-lowering effects of different oat bran (OB) preparations, differing regarding their peak molecular weight (MWp) of β-glucans (2348, 1311, 241, 56, 21 or < 10 kDa), in C57BL/6NCrl mice. The diets were designed to be atherogenic (0·8 % cholesterol and 0·1 % cholic acid), and they reflected the Western diet pattern (41 % energy fat). All OB preparations that were investigated significantly reduced plasma cholesterol when compared with a cellulose-containing control diet, regardless of the molecular weight of β-glucan. Moreover, the difference in viscous properties between the processed OB (from 0·11 to 17·7 l/g) did not appear to play a major role in the cholesterol-lowering properties. In addition, there was no correlation between the molecular weight of β-glucan and the amount of propionic acid formed in caecum. Interestingly, however, there was a significant correlation between the ratio of (propionic acid+butyric acid)/acetic acid and the MWpof β-glucans: the ratio increased with increasing molecular weight. The results of the present study suggest that the molecular weights and viscous properties of β-glucan in oat products may not be crucial parameters for their cholesterol-lowering effects.

Dependence of Tack Strength on Molecular Properties

1959 ◽  
Vol 32 (1) ◽  
pp. 48-66 ◽  
Author(s):  
W. G. Forbes ◽  
L. A. McLeod
Keyword(s):  
Molecular Weight ◽  
Shear Viscosity ◽  
Catalyst System ◽  
Chain Entanglement ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
The Difference ◽  
Catalyst Systems ◽  
Time Required ◽  
Butadiene Styrene

Abstract A method has been developed for the measurement of the tack strength of fresh and reproducibly smooth rubber surfaces. Using this method the tack strength of natural rubber is shown to be independent of polymer purity, and, to a large extent, Mooney viscosity, intrinsic viscosity, gel content and molecular weight distribution. The relative tack strengths of polyisoprenes of different molecular weights prepared in different catalyst systems are measured. The results are discussed in terms of microstructure. A study of the tack strength of oil-extended butadiene-styrene copolymers indicates that relative tack strength is related to the shear viscosity of the bulk polymer. Measurements of relative tack strength on Alfin and free radical butadiene-styrene copolymers, butyl, brominated butyl and butadiene-acrylonitrile copolymers confirm the inportance of shear viscosity in controlling tack strength. Choice of catalyst system and temperature of polymerization cause the largest variation in polymer viscosity. The contact time required for the relative tack strength to become unity is shown to be inversely dependent upon the value of the relative tack strength itself. Shear viscosity measurements are given for six classes of polymer and the values shown to correlate with relative tack strength. It is postulated that molecular weight (and probably also chain entanglement) is the controlling variable. The bond strength between two different uncured polymers is shown to depend upon the difference in cohesive energy densities of the two polymers.

scholarly journals An equation to estimate the difference between theoretically predicted and SDS PAGE-displayed molecular weights for an acidic peptide

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Yihong Guan ◽  
Qinfang Zhu ◽  
Delai Huang ◽  
Shuyi Zhao ◽  
Li Jan Lo ◽  
...  
Keyword(s):  
Molecular Weights ◽  
Sds Page ◽  
Acidic Peptide ◽  
The Difference

Effects of dextran on microvascular ischemia-reperfusion injury in striated muscle

1997 ◽  
Vol 272 (4) ◽  
pp. H1710-H1716 ◽  
Author(s):  
M. Steinbauer ◽  
A. G. Harris ◽  
K. Messmer
Keyword(s):  
Molecular Weight ◽  
Reperfusion Injury ◽  
Striated Muscle ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Capillary Density ◽  
Vessel Diameter ◽  
Functional Capillary Density ◽  
Molecular Weights ◽  
The Difference

The objectives of this study were 1) to elucidate the effects of dextran (Dx) at a nonhemodiluting dose of 5 mg/kg on ischemia-reperfusion injury in striated muscle and 2) to investigate whether the effects are dependent on the molecular weight of Dx. We used the model of a 4-h pressure-induced ischemia in the hamster skinfold chamber. By means of intravital microscopy the following parameters were assessed: vessel diameter, red blood cell velocity, rolling and adherent leukocytes, macromolecular extravasation, and functional capillary density. The animals received a continuous infusion (total dose 5 mg/kg) of dextran of different molecular weights or equivalent volumes of saline. Seven groups were studied: NaCl (control, n = 6), Dx 1 (n = 6), Dx 40 (n = 7), Dx 60 (n = 6), Dx 70 (n = 7), Dx 110 (n = 7), and Dx 150 (n = 7). Leukocyte rolling was reduced by all Dx fractions, the difference from the control reaching significance 0.5 h after reperfusion in the Dx 60, Dx 70, and Dx 110 group, whereas leukocyte adherence was attenuated by > 40,000-mol-wt Dx at 0.5 h after reperfusion. Concomitantly, functional capillary density tended to improve after treatment with > or = 40,000-mol-wt Dx. However, all Dx fractions studied failed to reduce postischemic macromolecular extravasation. These results provide evidence that Dx at 5 mg/kg attenuates postischemic microvascular disturbances; this effect is molecular weight dependent.

Identification and Genetic Analysis of a Common Molecular Variant of Histidine-rich Glycoprotein with a Difference of 2KD in Apparent Molecular Weight

1995 ◽  
Vol 74 (06) ◽  
pp. 1491-1496 ◽  
Author(s):  
B C Hennis ◽  
P A van Boheemen ◽  
S Wakabayashi ◽  
T Koide ◽  
J J M L Hoffmann ◽  
...  
Keyword(s):  
Consensus Sequence ◽  
Apparent Molecular Weight ◽  
Mendelian Inheritance ◽  
Glycosylation Site ◽  
Single Chain ◽  
Chain Molecules ◽  
Molecular Weights ◽  
Molecular Variants ◽  
Direct Sequence Analysis ◽  
The Difference

SummaryTwo forms of histidine-rich glycoprotein (HRG) were detected on SDS-PAGE by silver staining and immunoblotting after isolation of the protein from pooled plasma using immuno-affinity chromatography followed by chromatography with heparin-Sepharose. Both forms were single-chain molecules and the apparent molecular weights of form 1 and form 2 were 77 kD and 75 kD respectively. Mendelian inheritance of both HRG forms was observed in four families with 24 informative meioses, strongly suggesting that the two forms are encoded by different alleles. The frequency of form 1 and form 2 in a group of 36 individuals was 0.35 and 0.65 respectively.The difference between the two molecular variants was studied by direct sequence analysis of amplified exons of the HRG gene from 6 individuals who were homozygous either for form 1 or form 2. Five amino acid polymorphisms in three different exons were observed: Ile/Thr in exon 4; Pro/Ser in exon 5; His/Arg, Arg/Cys and Asn/Ile in exon 7. Analysis of these polymorphisms in 20 volunteers showed that only the Pro/Ser polymorphism at position 186 in exon 5 was coupled to the form of the HRG protein. Ser was found in form 1 and Pro in form 2. The presence of Ser at position 186 introduces a consensus sequence for a N-glycosylation site (Asn-X-Ser/Thr). By removing N-linked sugars with N-glycanase, it could be demonstrated that the difference between the two forms of HRG is caused by an extra carbohydrate group at Asn 184 in form 1.

scholarly journals Metamorphism of Dry Snow as a Result of Temperature Gradient and Vapor Density Differences

1983 ◽  
Vol 4 ◽  
pp. 3-9 ◽  
Author(s):  
E. E. Adams ◽  
R. L. Brown
Keyword(s):  
Temperature Gradient ◽  
Heat Conduction Equation ◽  
Temperature Gradients ◽  
Large Temperature ◽  
Local Minima ◽  
Vapor Density ◽  
Snow Density ◽  
Local Maxima ◽  
The Difference

A heat conduction equation for the determination of the temperature profile in a snowpack is developed. The magnitude of the temperature gradient tends to increase as the snow surface is approached, with local minima through layers of high snow density and local maxima above and below these layers. Calculations are made of the difference in vapor density in the pore and over the ice grain surfaces which border the pore. In the presence of sufficient temperature and temperature gradient, faceted crystals will develop near the top of the pore, as ice is sublimed away from the surfaces in the lower region. There will be a reduction in the percentage of rounded grains as the faceted form develops. The process is demonstrated to be enhanced at warm temperatures and large temperature gradients in low density snow.

scholarly journals Properties and structure of high temperature resistant cyanate ester/polyethersulfone blends using solvent-free toughening approach

2020 ◽  
Author(s):  
Lyaysan Amirova ◽  
Fabian Schadt ◽  
Markus Grob ◽  
Christian Brauner ◽  
Thomas Ricard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Temperature ◽  
Network Formation ◽  
Mechanical Analysis ◽  
Solvent Free ◽  
Cyanate Ester ◽  
Low Molecular Weight ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
The Difference

AbstractA high temperature resistant novolac cyanate ester was blended with polyethersulfone (PES) with different molecular weights using the solvent-free approach. The phase separation, curing behavior and thermal properties were studied using hot stage microscopy, differential scanning calorimetry and dynamic mechanical analysis. Results showed the difference in the morphology for blends with different molecular weight PES explained by possible network formation. The influence of PES content on the glass transition temperature and mechanical properties was investigated. The most significant toughening effect (increase of 132% in fracture toughness) was achieved on a functionalized low molecular weight PES (20 parts per hundred of resin, phr). Rheology investigation allowed to estimate the optimal content of PES (15 phr) for further prepreg manufacturing.

THE EFFECTS OF THE PAI DERIVED FROM HUMAN PLATELETS ON TWO DIFFERENT TYPES OF t-PA

1987 ◽  
Author(s):  
T Yasukouchi ◽  
T Fujie ◽  
S Sakurama ◽  
M Satoh ◽  
M Ikeo ◽  
...  
Keyword(s):  
Molecular Form ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Red Cross ◽  
Molecular Weights ◽  
Rich Solution ◽  
The Difference ◽  
Triton X ◽  
Important Significance ◽  
Short Incubation Time

We studied on the effect of PAI derived from human platelets on two different kinds of t-PAs; one was purchased from BioPool, Sweden, (human uterus or melanoma cell derived one-chain t-PA: one-chain u-mt-PA) and another was kindly supplied from Sumitomo Pharm. Co., Osaka, (recombinant two-chain t-PA: two-chain rt-PA). As the PAI-rich solution derived from platelets. We used the platelets extract, which was prepared as follows: The concentrated platelet-rich plasma (Red Cross Japan) was washed with phosphate buffer containing 0.4 % Triton X-100. The inhibitory activities of the PAI were measured by the method of parabolic rate assay and were calcurated from the activities remained in the mixtures of PAI and the t-PAs. The reactions of the PAI and the t-PAs were also analysed by the method of fibrin autography. The PAI suppressed the activity of two-chain rt-PA completely within 5 minutes, but could not suppressed that of one-chain u-mt-PA completely within such a short incubation time. These facts also recognized on fibrin autography. The molecular weights of both free t-PAs were recognized at 60 kDa and that of the complex of the PAI and two-chain rt-PA was recognized at 110 kDa, respectively. The fibrinolytic zone of the complex of PAI and one-chain u-mt-PA, however, could not be recognized. This indicates two possibilities; one is too small amounts of complex forming to detect and another is that SDS can not reveal the t-PA activity from the complex of PAI and one-chain u-mt-PA on fibrin autography. It remained unclear that the difference of the reactions of these t-PAs to PAI had been induced from whether the difference between one- and two-chain, or that between rt-PA and u-mt-PA. If the former is reasonable, it can be said that the molecular form of t-PA has an important significance in physiological fibrinolytic mechanism.

MOLECULAR WEIGHTS FROM MICRO QUANTITIES OF MATERIALS

1949 ◽  
Vol 27b (3) ◽  
pp. 151-157 ◽  
Author(s):  
I. E. Puddington
Keyword(s):  
Molecular Weight ◽  
Vapor Pressure ◽  
Chemical Compounds ◽  
Unknown Compound ◽  
Molecular Weights ◽  
Pure Solvent ◽  
Unknown Substance ◽  
The Difference

A method is proposed for the determination of the molecular weight of chemical compounds in which the unknown substance may be used successfully m quantities of 1 mgm. or less. The method depends on the accurate measurement of the difference in vapor pressure between a solution of the unknown compound and the pure solvent, and this is accomplished with a modified mercury U-tube manometer. The results presented indicate that the difference between the experimental and theoretical molecular weights is of the order of 2%. Determinations require from two to three hours and the sample may be recovered.

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