摘要:

Recent volumetric and calorimetric data have been used to calculate the excess functions for mixtures of water and hydrogen peroxide over the entire concentration range. The results are compared with those for the corresponding deuterium compounds. The existing calorimetric and vapor-pressure measurements are not comprehensive nor accurate enough to support discussion of the finer details of the excess quantities. A maximum in the excess-volume curves, presumably related to the formation of the compound H2O2.2H2O, persists in the liquid mixtures over an appreciable temperature range above the melting point of that compound. A possible crystal structure is proposed for the latter.New density determinations were carried out on mixtures of heavy water and deuterium peroxide at 0° and 20 °C. and the effect of deuterium peroxide on the temperature of maximum density of heavy water was measured and compared with that of deuterated alcohols. It is concluded that the structure of liquid water is easily penetrated by hydrogen peroxide molecules.

ISSN:0008-4042    

DOI:10.1139/v58-128

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

The activation of the myosin-catalyzed hydrolysis of adenosine triphosphate by calcium ions has been studied at pH 7.5 over a range of temperature extending from 3° to 25 °C. There is evidence that the activation is due to the equilibrium formation of a complex between adenosine triphosphate and calcium ions.From such a reaction mechanism, values of equilibrium constants are reported for the binding of adenosine triphosphate to the myosin in the presence and in the absence of calcium ions, together with stability constants for the calcium complexes of both the adenosine triphosphate and the myosin – adenosine triphosphate. The influence of hydrogen-ion concentrations on these constants is indicated.

ISSN:0008-4042    

DOI:10.1139/v58-129

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

A new alkaloid, lycodine, C17H24N2, m.p. 118°, has been isolated fromLycopodium annotinum. Lycodine is a tetracyclic diacidic base containing a secondary nitrogen atom, a 2,3-disubstituted pyridine ring, and a C-methyl group. The 2,3-disubstitution is in the form of a saturated six-membered ring.

ISSN:0008-4042    

DOI:10.1139/v58-130

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

The vapor pressure of lithium over the system lithium oxide – calcium oxide – silicon has been measured using the gas entrainment method at temperatures between 970 °C. and 1025 °C. The experimental results are summarized in the formwherePis in atmospheres andTin °A. The reaction, as usually written,does not describe the process completely.

ISSN:0008-4042    

DOI:10.1139/v58-131

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v58-132

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Treatment of methyl β-L-arabopyranoside under hydrogenolytic conditions with copper chromium oxide catalyst induces extensive isomerization. Products formed include glycosides ofD-ribose,D-xylose,D-lyxose, andL-lyxose which together represent about an 80–90% conversion of starting material. Isolation of these compounds shows that carbons 2, 3, and 4 undergo isomerization, but no evidence has been obtained of anomerization. These findings possibly explain the formation of an opticallyinactivemixture ofcis- andtrans-tetrahydropyran-3,4-diol under slightly more drastic reaction conditions.

ISSN:0008-4042    

DOI:10.1139/v58-133

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

By further chromatographic fractionation of the unsaponifiable matter from an extract of peat moss (Sphagnum) three crystalline triterpenes have been isolated. They have been identified as α-amyrin, taraxerone, and taraxerol by their physical and chemical properties.

ISSN:0008-4042    

DOI:10.1139/v58-134

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

The effect of various modes of drying upon the crystallinity of cellulose has been determined by X-ray diffraction.No change in the crystallinity index was observed when previously undried pure cellulose fibers from softwood were dried from water under a wide range of conditions, but a lower value was obtained when they were dried from benzene to which the fibers were accommodated by a series of solvent exchanges. Heat of wetting determinations on the same samples indicated changes in the accessibility with different drying methods. Qualitative variations in the degree of intrafiber bonding were also detected by a differential staining method. The X-ray measurements suggested that drying from water either produces no change in lateral order or that such changes are too small to be detectable by X-rays.The crystallinity of cellulose prepared by dry-milling whole fibers was studied. The crystallinity was substantially reduced in a Wiley mill and obliterated in a ball mill. X-Ray diffraction showed that wetting with water and then drying restored the crystallinity, while similar treatment with other liquids yielded less definite results. However, by following the destruction of the lattice with progressive periods of milling, it was concluded that alcohols reform this lattice to a limited extent depending, among other factors, upon the swelling capacity.

ISSN:0008-4042    

DOI:10.1139/v58-135

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Polycyclic aromatic compounds can, in a number of cases, be oxidized with chromyl chloride, whereas heterocyclic compounds are unaffected.

ISSN:0008-4042    

DOI:10.1139/v58-136

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Viscosity and light-scattering measurements were made on several fractions and two unfractionated samples of cellulose trinitrate. The samples were prepared from bleached ramie, unbleached ramie, and cotton linters. The solvents were acetone and ethyl acetate. Viscosity was measured in a multishear viscometer designed for the purpose. Light-scattering measurements were made in a Brice-Phoenix Light-scattering Photometer modified to accommodate a cell which could be ultracentrifuged.The range of molecular weight investigated was from 6.5 × 105to 25.0 × 105The relationship between thez-average mean-square radius of gyration,and thez-average molecular weight was approximately linear in both solvents. The ratio of(whereis the value ofin the unperturbed state) was found constant in acetone but to increase within ethyl acetate. This indicated that, whereas in acetone random coil configuration was attained, a configurational transition occurred in ethyl acetate in the molecular weight range investigated.The value of the exponentain the relationship between intrinsic viscosity and molecular weight was found to be lower than unity but approximately equal in both solvents.The significance of the experimental data is discussed.

ISSN:0008-4042    

DOI:10.1139/v58-137

出版商:NRC Research Press    

年代:1958

数据来源: NRC