摘要:

Viscosities and number average molecular weights of various carrageenin preparations, including thermally and photochemically degraded samples, have been measured. Aqueous solutions of carrageenin of low molecular weight are shown to exhibit viscosity characteristics which are entirely similar to those of other natural and synthetic polyelectrolytes. Solutions of carrageenin of high molecular weight exhibit plastic flow. The relationship between viscosity and molecular weight for the degraded polymer indicates that the molecular configuration in solution is that of a fairly stiff rod, even in the presence of salts.

ISSN:0008-4042    

DOI:10.1139/v54-009

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

1-β-Hydroxyethylimidazolidine-2-thione was prepared from 1-amino-5-hydroxy-3-azapentane and carbon disulphide. Since its properties differ from those claimed by Sergeyev and Kolychev (7) for this compound prepared from ethylene oxide and thiocyanic acid, its structure was confirmed by conversion to 1-β-hydroxyethyl-2-benzylamino-2-imidazoline. The latter compound was prepared for comparison from the known 1-β-hydroxyethyl-2-nitramino-2-imidazoline.

ISSN:0008-4042    

DOI:10.1139/v54-010

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The effect of fluctuations in free radical concentrations on the values of relative reaction rate constants calculated from steady state expressions has been evaluated for a number of idealized model cases, representative of various conditions usually encountered in experiments.

ISSN:0008-4042    

DOI:10.1139/v54-011

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Coefficients of self-diffusion have been measured for aqueous solutions of sodium dihydrogen phosphates from 1 molar to 10−4molar and at temperatures of 15, 25, 35, and 45 °C. The activation energy of self-diffusion has been calculated for various concentrations. It decreases from 5.4 kcal./mole at 0.9 Mto 4.3 kcal./mole. at infinite dilution.

ISSN:0008-4042    

DOI:10.1139/v54-012

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

By mass spectrometric analyses, methyl ethyl ketone was determined as a product of the photolysis of acetone between 100 and 284 °C. According to the postulated mechanism, methyl ethyl ketone together with methane and ethane accounted for approximately 95% of the methyl radicals produced.

ISSN:0008-4042    

DOI:10.1139/v54-013

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Dicranostigmafranchetianumhas been renamedStylophorumfranchetianum(Prain) comb. nov. because its alkaloids are the same as those ofS.diphyllum. It is proposed to retain the nameD.lactucoidesbecause the contained alkaloids, namely protopine, isocorydine, sanguinarine, and chelerythrine present a combination hitherto encountered only in aGlaucium.Bocconiapearceiwas shown to contain, in addition to chelerythrine (and presumably sanguinarine), small amounts of protopine and allocryptopine.

ISSN:0008-4042    

DOI:10.1139/v54-014

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The influence of temperature on the sedimentation volume and relative yield values of suspensions of spherical glass beads in toluene containing varying percentages of water has been measured. The increased sedimentation volume and yield value, due to the presence of water, found at room temperature virtually disappeared below approximately 0 °C. This is in agreement with the theory which ascribes the effect of water to its interfacial tension against toluene. At temperatures above 0 °C. there was a gradual fall in the sedimentation volume and yield value from the maximum found at 0 °C. This is attributed to the increasing solubility of water in toluene. Suspensions containing no water or only a small quantity showed an unexpected steady increase in sedimentation volume and yield value as the temperature was lowered to −60 °C. This effect was also observed with a suspension of glass beads in pentane. The results indicate a close connection between yield value and equilibrium sedimentation volume.

ISSN:0008-4042    

DOI:10.1139/v54-015

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The positron emitting Na22of 2.6 year half-life has been prepared in a nuclear reactor by the double reaction Li6(n, α)H3, Ne20(H3,n)Na22. The over-all yield was 2.3 × 10−7atoms of Na22per atom of tritium formed. Eleven grams of lithium as aluminum alloy turnings in a neon atmosphere at 200 p.s.i. was irradiated for 175 days in a neutron flux of about 4 × 1012 n./cm.2/sec. About 380 μc. of Na22was obtained in a sodium extract having a specific activity of 10 mc. Na22/gm. of Na23. A specific activity in the curie/gm. level would be expected from a longer irradiation in the highest flux (6 × 1013 n./cm.2/sec.) in the NRX reactor. The separation and purification of the sodium proved practicable by paper chromatography or ion exchange; the analyses for trace Li and Na23were carried out by radioactivation.

ISSN:0008-4042    

DOI:10.1139/v54-016

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Extensive PVT measurements of xenon extending from 1.8° above the critical temperature to the critical temperature, and in a few cases to 4 ° below the critical temperature, have been carried out at densities ranging from somewhat above the critical density to well below. In order to make the corrections for hydrostatic head small and easily calculable, a bomb having a height of only 1.0 cm. was used in the present measurements. The previously reported value for the critical temperature 16.590° is confirmed. The critical density is estimated to be 1.099 ± 0.002 gm./ml. compared with 1.105 gm./ml. found previously. The critical pressure is found to be 57.636 ± 0.005 atm.The isotherms at temperatures above the temperatures of meniscus disappearance do not appear to have any flat portions. However, the critical isotherm is considerably flatter and broader over a range of densities than that corresponding to a van der Waals equation, and at the critical point the third and fourth derivatives of pressure with respect to volume appear to be zero.

ISSN:0008-4042    

DOI:10.1139/v54-017

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Mercury dimethyl was photolyzed in the presence of deuterium in the temperature range from 27 °C. to 253 °C. The activation energy for the reactionwas found to be 12.7 ± 0.5 kcal./mole. This is in satisfactory agreement with the work done with acetone and deuterium.

ISSN:0008-4042    

DOI:10.1139/v54-018

出版商:NRC Research Press    

年代:1954

数据来源: NRC