The role of terphenyl-containing carboxylic acid in the oligomerization of aryl vinyl ketone.

The molecular structure of 8-((4''-((1R,4S)-4-butylcyclohexyl)-2'-chloro-[1,1',4',1''-terphenyl]-4-yl)oxy)oct-1-en-3-one (TERPh-VK) and 6-((4''-((1R,4S)-4-butylcyclohexyl)-2'-chloro-[1,1':4',1''-terphenyl]-4-yl)oxy) hexanoic acid (TERPh-COOH) is analyzed by FTIR spectroscopy. Vinyl ketone isolated from solution forms a thermodynamically unstable cis conformation due to probable peculiarities of the crystal structure formation. The heating of this substance above 100 °C results in the cis-trans transformation with the simultaneous opening of the vinyl double bond. The mixing of the above terphenyls in solution followed by the isolation of the solid product results in the formation of the TERPh-VK/TERPH-COOH associated species due to the H-bonding between ketone and carboxylic groups. The thermal transformation of the H-bond associated species resulted in the formation of the oligo (TERPh-VK)/TERPh-COOH associated species.

A study of the radiation environment on board the Space Shuttle flight STS-57.

A joint NASA-Russian study of the radiation environment inside a SPACEHAB 2 locker on Space Shuttle flight STS-57 was conducted. The Shuttle flew in a nearly circular orbit of 28.5 degrees inclination and 462 km altitude. The locker carried a charged particle spectrometer, a tissue equivalent proportional counter (TEPC), and two area passive detectors consisting of combined NASA plastic nuclear track detectors (PNTDs) and thermoluminescent detectors (TLDs), and Russian nuclear emulsions, PNTDs and TLDs. All the detector systems were shielded by the same Shuttle mass distribution. This makes possible a direct comparison of the various dose measurement techniques. In addition, measurements of the neutron energy spectrum were made using the proton recoil technique. The results show good agreement between the integral LET spectrum of the combined galactic and trapped particles using the tissue equivalent proportional counter and track detectors between about 15 keV/micrometers and 200 keV/micrometers. The LET spectrum determined from nuclear emulsions was systematically lower by about 50%, possibly due to emulsion fading. The results show that the TEPC measured an absorbed dose 20% higher than the TLDs, due primarily to an increased TEPC response to neutrons and a low sensitivity of TLDs to high LET particles under normal processing techniques. There is a significant flux of high energy neutrons that is currently not taken into consideration in dose equivalent calculations. The results of the analysis of the spectrometer data will be reported separately.

Experimental and calculated LET distributions in the Cosmos-2044 biosatellite orbit.

During the flight of the Cosmos-2044 biosatellite, joint U.S.S.R.-U.S.A. investigations of different characteristics of cosmic radiation (CR) in the near-Earth environment were carried out. The U.S. dielectric track detectors CR-39 and Soviet BYa- and BR-type nuclear photo-emulsions were used as detectors. The present work shows some results of experimental measurements of linear energy transfer (LET) spectra of CR particles obtained with the use of these detectors, which were placed both inside and outside the satellite. The LET spectra measurement with plastic detectors is composed of two parts: the measurement of galactic cosmic rays (GCR) particles, and of short-range particles. The contributions of these components to the total LET distribution at various thicknesses of the shielding were analyzed and the results of these studies are presented. Calculated LET spectra in the Cosmos-2044 orbit were compared with experimental data. On the basis of experimental and calculated values of the LET spectra, absorbed and equivalent CR doses were calculated. In the shielding range of 1-1.5 g cm-2, outside the spacecraft, the photo-emulsions yielded 10.3 mrad d-1 and 27.5 mrem d-1 (LET > or = 2 MeV cm-1) while the CR-39 yielded averages of 1.43 mrad d-1 and 13.4 mrem d-1 (LET > or = 40 MeV cm-1). Inside the spacecraft (> or = 10 g cm-2) the photo-emulsions yielded 8.9 mrad d-1 and 14.5 mrem d-1.