摘要:

In previous papers1–5the remarkable properties of a liquid birefringent phase that separates from certain solutions of polypeptides in organic solvents when a limiting concentration is exceeded have been described. This phase, first observed by Elliott and Ambrose1in solutions of poly-γ-benzyl-L-glutamate (PBLG) shows microscopically visible periodicities and a very high optical rotatory power.2The order of magnitude of the optical rotatory power is comparable to that exhibited by the well-known cholesteric liquid crystals21,22formed by esters and ethers of cholesterol, and which also show visible periodicities (the Grandjean layers) although these are smaller than the periodicties in the PBLG solutions.

ISSN:0369-1152    

DOI:10.1080/15421406608083287

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The skin over subcutaneous lesions of primary or metastatic carcinomas and sarcomas is frequently warmer than the apparently normal surrounding skin.1–3Thus thermotopographic measurement of skin temperature over tumor lesions can be useful for measurement of size, vascular physiology and response to treatment.

ISSN:0369-1152    

DOI:10.1080/15421406608083288

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The proton magnetic resonance spectra of some acetylenic compounds, acetonitrile and methanol, oriented in the nematic phase of 4, 4-di-n-hexyloxy-azoxy benzene or 4-n-octyloxy-benzoic acid have been investigated. From the chemical shift difference of the signals of the acetylenic proton in the isotropic and nematic phase a value of 12± 1.5 ppm is obtained for the anisotropy of the chemical shift. From the spectra of oriented acetontrile-2−13C and methanol−13C accurate values for the H-C-H bond angle of the methyl groups are derived. The absolute sign of the indirect spin coupling constant J13CHin acetonitrile-2-13C has been found to be positive.

ISSN:0369-1152    

DOI:10.1080/15421406608083289

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

In homogeneously ordered liquid crystals of the nematic type, two principal dielectric constants can be measured: ϵ1 parallel and ϵ2 perpendicular to the symmetry axis of the liquid crystal. The two dielectric constants may show a very different relaxation behavior. With alkoxy derivatives of azobenzene, only the normal Debye dispersion region at microwave frequencies has been observed. With alkoxy derivatives of azoxybenzene, ϵ2 shows again only the normal Debye dispersion region at microwave frequencies, but ϵ1 has an additional dispersion at very unusually low frequencies in the radio region. This dispersion is due to the permanent electric dipole momment of the azoxy group, more exactly to its component parallel to the long molecular axis. The reorientation of this component in direction 1 is hindered by a potential barrier due to intermolecular forces. The corresponding relaxation time is increased by a factorg. Starting from a modification of the Debye theory of dielectric relaxation, this retardation factor may be used to calculate the height of the potential barrier. Numerical values are in satisfactory agreement with other values, calculated from the observed long range order.

ISSN:0369-1152    

DOI:10.1080/15421406608083290

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The average orientation of benzene and some chlorine substituted benzene derivatives in a nematic liquid crystalline solution has been determined. 1,2,3-trichlorobenzene was used to study the influence of a permanent electrical dipole moment. It was measured in different nematic solvents of positive and of negative dielectrical anisotropy. There is no or only little variation in the relative average orientation of the principal molecular axes. It shows that the forces between permanent electrical dipole moments are of minor importance for the average orientation.

ISSN:0369-1152    

DOI:10.1080/15421406608083291

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Lyotropic liquid crystals given by binary systems have been known for a long time to investigators in the soap and detergent field, mainly by the work of McBain and his school.1, 2The first analysis by X-ray diffraction of soap mesophases was done by Stauff3and by Kiessig and Philippoff.4Liquid crystals obtained with phospholipids in the presence of water were examined by X-ray analysis already in 1941 by Schmittet al.5More recently Luzzatiet al.6defined the structure of the different mesophases with more precision.

ISSN:0369-1152    

DOI:10.1080/15421406608083292

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

There are several good theoretical reasons why matter in the liquid crystalline state should play a part in the structure of living tissue.

ISSN:0369-1152    

DOI:10.1080/15421406608083293

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor