Effect of acyl chain length on the structure and motion of gramicidin A in lipid bilayers

The transmembrane ion transport properties of gramicidin A have previously been shown to dependent on the nature of its lipid environment. Solid-state NMR spectroscopic studies of 13C-labelled analogues of gramicidin in oriented multilayers of phosphatidylcholine have shown that variation of the lipid hydrocarbon chain length has no effect on the structure or orientation of the peptide backbone.     

Biodegradation of Glycidol and Glycidyl Nitrate

When calcium hydroxide is used to desensitize glycerol trinitrate (nitroglycerine)-containing waste streams, the epoxides glycidol and glycidyl nitrate are formed. The epoxide rings of both compounds are unstable to heat in aqueous solutions, and they open to form glycerol 1-mononitrate and presumably glycerol. These transformations were accelerated by microbial activity. Glycerol 1-mononitrate was slowly denitrated to form glycerol. Glycidol and glycidyl nitrate caused base-pair substitutions in the Ames test for mutagenicity, whereas glycerol 1-mononitrate tests were negative.     

Microviscosity of human erythrocytes studied with hypophosphite and 31P-NMR

A 31P-NMR method, which complements earlier 13C-NMR procedures for probing the intra-erythrocyte microenvironment, is described. Hypophosphite is an almost unique probe of the erythrocyte microenvironment, since it is rapidly transported into the cell via the band 3 protein, and intra- and extracellular populations give rise to distinct resonances in the 31P-NMR spectrum. Relaxation mechanisms of the 31P nucleus in the hypophosphite ion were shown to be spin-rotation and dipole-dipole. Analysis of longitudinal relaxation rates in human erythrocytes, haemolysates and concentrated glycerol solutions allowed the determination of microviscosity using the Debye equation. Bulk viscosities of lysates and glycerol solutions were measured using Ostwald capillary viscometry. Translational diffusion coefficients were then calculated from the viscosity estimates using the Stokes-Einstein equation. The results with a range of solvent systems showed that 'viscosity' is a relative phenomenon and that bulk (i.e., macro-) viscosity is therefore not necessarily related to the NMR-determined viscosity. The intracellular NMR-determined viscosities from red cells, ranging in volume from 65.5 to 100.1 fl, varied from 2.10 to 2.67 mPa s. This is consistent with the translational diffusion coefficients of the hypophosphite ion altering by only 20%, whereas the values determined from bulk viscosity measurements conducted on lysates of these cells are consistent with a 230% change.     

Dispersal distances attained by insect populations of different densities

Different population categories of apterous green peach aphid, adult sweet potato weevils, mature Caribbean fruit fly larvae and tobacco budworm larvae were permitted to move on dispersion ranges in the laboratory. Determination of distances dispersed by the larvae were made to show the effects of population sizes. In general, longer distances were dispersed by more individuals when larger numbers were released as compared with smaller ones.     

Research and Development of High-performance Explosives

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. small-scale For newly developed formulations, the process begins with small-scale mixes, thermal testing, and impact and friction sensitivity. Only then do subsequent larger scale formulations proceed to detonation testing, which will be covered in this paper. Recent advances in characterization techniques have led to unparalleled precision in the characterization of early-time evolution of detonations. The new technique of photo-Doppler velocimetry (PDV) for the measurement of detonation pressure and velocity will be shared and compared with traditional fiber-optic detonation velocity and plate-dent calculation of detonation pressure. In particular, the role of aluminum in explosive formulations will be discussed. Recent developments led to the development of explosive formulations that result in reaction of aluminum very early in the detonation product expansion. This enhanced reaction leads to changes in the detonation velocity and pressure due to reaction of the aluminum with oxygen in the expanding gas products.     

Progress report: Results of a long-range captive breeding program for the bottlenose dolphin,Tursiops truncatus and Tursiops truncatus gilli

There have been 36 bottlenose dolphins born in breeding colonies at Sea World, California, and Sea World, Florida, from 1978–1985. Significant features of this successful reproductive program are construction of a compatible breeding colony, early hormonal detection of pregnancy, pre- and postnatal association of inexperienced mothers with experienced females and their calves, and minimized handling of the mothers and calves until the calves are over 1 year of age. Inclusion in the breeding colonies of males old enough to be effective breeders is stressed. Females in the colonies have successfully bred from 8–9 years of age to 23–24 years of age. Calving intervals in the colonies vary from 2 to over 3 years. Calves are born all year round, with some peaking in calving activity in the spring and fall months. Serum progesterone levels greater than 6,000 pg/ml, maintained over a 4–6-week period, are considered indicative of pregnancy. Progesterone levels vary from less than 10,000 to over 50,000 pg/ml during gestation, averaging 25,000 pg/ml. The need for further study of variation in the pattern of progesterone levels during pregnancy is emphasized. A gestation period for Tursiops of 11.5 to 12 months is consistent with our cumulative progesterone data.