WAX SECRETION IN THE COCKROACH

1955 ◽  
Vol 32 (3) ◽  
pp. 514-538
Author(s):  
J. W. L. BEAMENT
Keyword(s):  
Molecular Weight ◽  
Periplaneta Americana ◽  
Freezing Point ◽  
Surface Active Properties ◽  
Surface Active ◽  
Solvent Molecules ◽  
Water Saturated ◽  
Chain Lengths ◽  
Novel Design ◽  
Surface Balance

An investigation has been made into the properties of the grease layer which waterproofs the cuticle of the cockroach Periplaneta americana. This grease changes slowly into a hard wax if stored in air. The melting-point rises during this process by 20° C. It is shown that the grease consists of a hard wax (m.p. 56° C.) dissolved in a ‘solvent’ which is liquid at room temperatures; there may be equal amounts of wax and of solvent. It is suggested that the series of paraffins and alcohols which probably compose the wax extend into the short-chain lengths, C8-C12 to provide the solvent. A micro-freezing-point method for determining the molecular weight of wax samples is described (based on Ramsay's method for aqueous solutions); the molecular weight of the solvent lies between 120 and 170, and of the hard wax--300-350. A method is also outlined for collecting large quantities of cockroach wax. Of a large range of lipophilic liquids, which dissolve waxes, only octane, decane, octyl and decyl alcohols are miscible in all proportions with insect waxes, and form synthetic greases with beeswax and with the hard wax of the cockroach. The surface-active properties of the natural and synthetic greases have been compared on a surface balance of novel design which is described in the Appendix. The two materials are remarkably similar; the surface balance has been used to confirm the size of the solvent molecules. An apparatus is described which enables the continuous measurement of water transport through an insect membrane in a water vapour/vapour gradient, and in the presence of other vapours. As opposed to the effect of the most organic wax solvents, the vapour of an octane-octyl alcohol mixture does not alter the permeability of a natural insect cuticle to water; exposure of an artificially waxed membrane to this vapour and water increases its impermeability. Evidence is provided for believing that octane-octyl alcohol mixtures will improve the waterproofness of most ‘imperfectly’ waxed membranes. The natural grease of the cockroach is a strong reducing agent, and evidence is produced for believing that the lipoid part is entirely saturated, but that it contains a small portion of substances resembling shellac. It is suggested that this represents the ‘cement’ layer of the cockroach cuticle. The importance of spreading agents with wax solubility in the formation of insect waterproof layers is discussed; it is suggested that the presence of a water-saturated substrate is an essential part of this process.

Cryoscopic and Viscosity Studies of Polyisobutylene. Cryoscopic Deviation of Polyisobutylene Solutions from Raoult's Law

1943 ◽  
Vol 16 (1) ◽  
pp. 69-84
Author(s):  
A. R. Kemp ◽  
H. Peters
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Infinite Dilution ◽  
Freezing Point ◽  
Raoult’S Law ◽  
Ideal Solutions ◽  
Chain Lengths ◽  
Selection Of ◽  
Raoult's Law

Abstract 1. The cryoscopic method is not satisfactory for polyisobutylenes having chain lengths much over 40 isobutylene units, on account of the failure of their solutions to obey Raoult's law. 2. The present work has led to the selection of a Kcm value of 0.75×104 for n-hexane solutions of polyisobutylene for use in the equation M=(log ηr×Kcm)/C. 3. Extrapolation of cryoscopic data obtained on nonideal solutions to infinite dilution gives inordinately high molecular weight values compared with those based on freezing point measurements of ideal solutions. 4. Of several solvents studied, n-hexane was found to be the best for viscosity—molecular weight measurements of polyisobutylene. 5. Fractionation of polyisobutylene by diffusion into mixtures of n-hexane and acetone resulted in the separation of the lower polymer fractions.

Solvation properties of ubiquinone-10 in solvents of different polarity

1986 ◽  
Vol 6 (9) ◽  
pp. 783-796 ◽  
Author(s):  
Monica Ondarroa ◽  
Santosh K. Sharma ◽  
Peter J. Quinn
Keyword(s):  
Surface Tension ◽  
Solvent Mixtures ◽  
X Ray Diffraction ◽  
Polar Solvents ◽  
X Ray ◽  
Air Water Interface ◽  
Surface Active ◽  
Solvent Molecules ◽  
Ubiquinone 10 ◽  
Surface Balance

The solvation properties of ubiquinone-10 and ubiquinol-10 in a wide variety of solvents of polarity varying from alkanes to water are reported. Greatest solubility is observed in solvents of intermediate polarity and particularly where low polarity is combined with a pronounced tendency to interact with the benzoquinone substituent of the ubiquinone molecule. This includes solvents like chloroform and benzene. Ubiquinone-10 is somewhat less polar than ubiquinol-10 as judged by comparative solubilities of the two molecules. Proton-NMR chemical shift measurements and aggregation studies in selected solvents indicate that in ubiquinone-10 in the liquid phase and in solution in hydrocarbons like dodecane the molecules have a preferred association possibly involving stacking of the benzoquinone rings. Surface balance studies indicated that the surface-active character of ubiquinone-10 is relatively weak and only in a comparatively polar and highly structured solvent, formamide, was there evidence of an effect on surface tension of the solvent. The critical micelle concentratiom in this solvent was estimated to be about 5 μM on the basis of surface tension measurements. Ubiquinone-10 is well known to form virtually insoluble monolayers at the air/water interface. Studies of the partition of ubiquinone-10 in binary mixtures of solvents suggest that the interaction of the benzoquinone ring substituent with structured polar solvents is considerably weaker than the internal cohesion between molecules of the solvent. No evidence on the basis of wide-angle X-ray diffraction measurements was obtained to indicate that solvent molecules were a component of the crystal lattice of ubiquinone-10 that had precipitated from solvent mixtures.

scholarly journals Novel polymer surfactants based on the branched silatrane-containing polyesters and polyethers

2019 ◽  
Vol 14 (5) ◽  
pp. 61-70 ◽  
Author(s):  
V. V. Istratov ◽  
V. I. Gomzyak ◽  
O. V. Yamskova ◽  
G. D. Markova ◽  
L. G. Komarova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Degree Of Substitution ◽  
Biologically Active ◽  
Hydroxyl Groups ◽  
Critical Micelle Concentrations ◽  
Surface Active Properties ◽  
Hydrophilic Lipophilic Balance ◽  
Surface Active ◽  
The Stability ◽  
Polymer Surfactants

Objectives. Biologically active polymeric surfactants are a new promising class of macromolecules that can find application in medicine, cosmetology, and agriculture. In this study, a number of new biologically active amphiphilic polymers based on branched silatrane-containing polyesters and polyethers were obtained, and their surface-active properties were investigated.Methods. The branched polymers were represented by polyethers and polyesters, obtained respectively via the anionic polymerization of 1,2-epoxypropanol or a combination of equilibrium polycondensation and ring opening polymerization. The polymers were modified with 3-isocyanopropylsilatrane and trimethylethoxysilane to obtain the amphiphilic compounds containing silatrane groups bonded to the polymer backbone by the urethane bond. The structure of the synthesized polymer silatranes was confirmed via nuclear magnetic resonance spectroscopy and gel permeation chromatography. The surface active properties of all the copolymers obtained were investigated in connection with their obvious amphiphilicity. In particular, the formation of micelles in aqueous solutions is such a property. The critical micelle concentrations were determined by a method of quenching the fluorescence of the polymers.Results. It was shown that the values of the critical micelle concentrations and the hydrophilic-lipophilic balance values of polymers determined by the Griffin equation correlate well with each other. A linear relationship between the hydrophilic-lipophilic balance and the critical micelle concentrations was established. At the same time, polyether-based polymers generally showed higher critical micelle concentrations than polyester-based polymers, although the hydrophilic-lipophilic balance values for polymers of different series, but with close degrees of substitution, were close. It was found that the use of all synthesized polymers as stabilizers of direct and reverse emulsions leads to an increase in the aggregative stability of both types of emulsions. The stability of emulsions depended both on the degree of substitution of peripheral hydroxyl groups of polymers by silatranes and on the molecular weight and structure of the branched block of polymers. The stability of direct emulsions increased for all polymers, while that of inverse emulsions decreased with an increasing degree of substitution of hydroxyl groups by silatranes. The increase of the branched block molecular weight led to an increase of droplet sizes for both direct and inverse emulsions. The smallest droplet size for direct and inverse emulsions was obtained using polymers with low molecular weight branched polyester blocks as surfactants.Conclusions. The results obtained prove the possibility of creating polymer surfactants containing silatrane groups. By varying the structure of the polymer, its molecular weight and the degree of substitution of peripheral functional groups, it is possible to obtain surfactants with desired surface properties.

scholarly journals Research of surface-active properties and sizes of pectin molecules after post-alcohol grain distillery dreg

2021 ◽  
Vol 640 (5) ◽  
pp. 052014
Author(s):  
A S Kaishev ◽  
N S Kaisheva ◽  
H N Gyulbyakova ◽  
E A Maslovskaya ◽  
V A Karpenko
Keyword(s):  
Surface Active Properties ◽  
Surface Active

scholarly journals Facile construction of a family of supramolecular gels with good levofloxacin hydrochloride loading capacity

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12641-12648
Author(s):  
Renyuan Chen ◽  
Caidie Xu ◽  
Yihao Lei ◽  
Hongxin Liu ◽  
Yabin Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Alkyl Chain ◽  
Low Molecular Weight ◽  
Loading Capacity ◽  
Supramolecular Gels ◽  
Low Molecular Weight Gelators ◽  
Chain Lengths

A family of low molecular weight gelators with different alkyl chain lengths was constructed, having excellent gelation ability and antibiotic loading capacity. A low molecular weight hydrogelator was obtained by adjusting the length of alkyl chain.

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