摘要:

An estimation of the hydrolytic stability of naturally occurring peptides and homologous sequences within protein chains has been made using Newman's “Rule of Six.” All possible sequences and their corresponding cumulative steric values, “six numbers,” were computer-generated. Those sequences having identical six numbers were grouped as families. The results of this study suggest that, in abiogenesis, peptides and proteins may have most often simply evolved to sequences which are members of the permutationally more populated sequence families.

ISSN:0022-233X    

DOI:10.1080/00222337008069372

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

It has been established that the dark conduction of isatin-[thiophene]-indophenine and of three polymers in which it is a repeating unit is described by the expression [sgrave] = [sgrave] exp (Eact/kT). The indophenine repeating units in the polymers are connected with a single bond, an oxygen atom, or a methylene group. The electronic spectra in solution and in the solid state indicate that these bonds between the basic units do not interrupt the conjugation along the chain. There is no correlation between the activation energy calculated from optical data and the thermal activation energy of conduction. The latter is considered as a sum of the energy necessary for the generation of the carriers and the energies needed to overcome the intramolecular and intermolecular potential barriers. The values of the parameters characteristic of the semiconducting properties are determined in the first place by the structure of the polymers as a solid body. Crystallinity tends to improve the electrophysical properties. The participation of heteroatoms and groups in the polymer chain, provided they do not interrupt the conjugation, has a favorable effect in cases where their presence improves the intermolecular interaction. A “compensation effect” is to be observed for all substances in vacuum and in air. The experimental data are best explained by the hopping model of electrical conduction.

ISSN:0022-233X    

DOI:10.1080/00222337008069373

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Polydipropylsiloxane single crystals, grown from a dilute n-butylacetate solution, were characterized by electron microscopy and by selected-area electron-beam diffraction techniques. The electron diffraction study shows that the growth face was parallel to the (100) plane. Fracture of single crystals parallel to the fold plane takes place during the electron diffraction examination to give ribbon like lamellae about 300 A wide and 80 A thick. Fracture normal to the fold plane was also observed.

ISSN:0022-233X    

DOI:10.1080/00222337008069374

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This paper presents a kinetic study of the copolymerization of acrylonitrile (AN, M2) with allyl alcohol (AOH, M2) in zinc chloride aqueous solution. The monomer reactivity ratios, r1and r2, determined by application of the Lewis-Mayo equation to the system, are 1.60 and 0.01, respectively. The observed value of copolymer composition agrees well with one calculated by use of computer up to higher conversion. This means that the Lewis-Mayo equation may be applicable to the present system. The possibility of homopolymerization of AOH, confirmed empirically, is also sustained by numerical calculation.

ISSN:0022-233X    

DOI:10.1080/00222337008069375

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Recent experiments in our laboratories [1–31], have shown that the technique of gas chromatography may be utilized to obtain extensive information about polymer structure and interactions in the solid phase. Although it might appear logical to apply the name “gas chromatography of polymers” to such experiments, the terminology is misleading in that the polymer is obviously not in the gas phase, nor is it undergoing a chromatographic separation. The terms GLC (gas-liquid chromatography) and GSC (gassolid chromatography) appear to be equally inapplicable for similar reasons. In fact, the nature of the experiment has more in common with the molecular beam technique for gaseous reactions and we prefer therefore to refer to these as studies on polymers using “molecular probes.”

ISSN:0022-233X    

DOI:10.1080/00222337008069376

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222337008069377

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222337008069361

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor