Mechanical properties of a composite with a carbonized matrix

The effect of reinforcement schemes that differ in the magnitude of the disorientation angle of neighboring filler layers on the mechanical properties of a "carbon-carbon" composite under extension, compression, or bending is shown.Translated from Mekhanika Polimerov, No. 2, pp. 235–240, March–April, 1976.     

Ground state of π-conjugated polymer chains forming an intermolecular charge-transfer complex as probed by Raman spectroscopy

The intermolecular charge-transfer complex (CTC) between the conjugated polymer MEH-PPV and the low-molecular organic acceptor trinitrofluorenone (TNF) has been studied by Raman and optical absorption spectroscopy. On mixing MEH-PPV with TNF, an absorption band due to the CTC appeared in the optical gap of the polymer, whereas, in the Raman spectra, characteristic bands of the polymer are shifted and their widths and intensities change. The low-frequency shift of the strongest band at 1580 cm^?1 in the Raman spectrum of the polymer, assigned to the symmetric stretching vibration of the phenyl group, is shown to be due to electron density transfer from the π-conjugated system of the polymer to the acceptor and is as large as 5 cm^?1, which corresponds to a charge transfer on the order of 0.1e ^?1. Even at a low acceptor concentration (one TNF molecule per 10 monomer units of the polymer), most Raman-active conjugated chains are involved in the CTC. It is suggested that conjugated segments of the polymer can form a CTC of variable composition MEH-PPV: TNF = 1: X, where 0.1 ≤ X ≤ 0.5 (for each monomer unit of the polymer), and one TNF molecule can thereby interact with two conjugated segments of MEH-PPV. The conjugated polymer chains involved in the CTC can become more planar, and their interaction with the local environment can noticeably change; however, their conjugation length, most likely, remains unaltered.     

About Cosmic Ray Sources in Galaxy

Physics of Atomic Nuclei - In the last two decades the new experimental data on cosmic rays concerning energy spectra in a wide energy range up to 10 $${}^{14}$$ eV, isotropy, ratio of positron...     

Photocatalytic Conversion of a FeCl<Subscript>3</Subscript>–CCl<Subscript>4</Subscript>–ROH System

The photocatalytic transformations of carbon tetrachloride and aliphatic primary alcohols in the presence of iron trichloride and a molar ratio of components FeCl₃: CCl₄: ROH = 1: 300: 2550 were studied. CCl₄ is transformed into chloroform and hexachloroethane after exposure to a mercury lamp (250 W) to the FeCl₃–CCl₄–ROH system at 20°C, whereas the primary ROH alcohols are selectively oxidized into acetals (1,1-dialkoxyalkanes). The maximum conversion of CCl₄ reaches 80%. The kinetics and mechanism of the photocatalytic conversion of the FeCl₃–CCl₄–ROH system are considered.     

Rainfalls during great Forbush decreases

Summary The changes of rainfall values during great Forbush decreases recorded by the low-latitudinal neutron monitor of Huancayo (47 events from 1956 through 1992) were examined. The data on precipitations were taken from the State of S?o Paulo and from the Amazonian region, Brazil. As a rule, the data from more than 50 meteorological stations were used for each events. The main result is the following: during strong decreases of cosmic-ray flux in the atmosphere (great Forbush decreases) the precipitation value is decreased. The effect of rainfall changes is seen more distinctly if wet seasons are considered.     

Latitude effect of muons in the Earth’s atmosphere during solar activity minimum

The results of muon flux measurements (E ≥ 70 MeV) in the atmosphere during solar activity minimum are reported. The measurements were performed during Antarctic sea expedition in 1975–1976 at several geomagnetic locations (from 1 to 14 GV). The experimental data obtained made it possible to determine the latitude effect of muons in the distribution at different levels in the atmosphere. The Geant4 program was used to simulate the galactic cosmic ray transport in the Earth’s atmosphere and evaluate the angular and spectral distributions (p, e^?/e⁺, photons, muons) at different atmospheric levels. The experimental and simulated results are in satisfactory agreement.     

A 19F NMR study of products of hexafluorobutadiene sulfotrioxidation

The products of hexafluorobutadiene sulfotrioxidation were identified by ¹⁹F NMR. The major products are hexafluoro-1-butene-3,4-β-sultone, hexafluoro-2-butene-1,4-sultone, hexafluoro-1-butene-3,4-pyrosultone, and hexafluoro-2-buten-1,4-diyl sulfate.     

On the Reproduction of the Solar Activity Variations in the Range 2–40 Months in the Interplanetary Medium

Journal of Experimental and Theoretical Physics - We compare the quasi-biennial variations and Rieger-type variations (on a timescale of less than 1&nbsp;year) in solar activity, interplanetary...     

Solar particle events observed on MIR station.

Radiation impact of the SPEs on board the MIR space station and in the interplanetary space is discussed in the report. The data of the on-board radiation dosimeter R-16 were used to measure the SPE absorbed doses. Some of SPEs (such as September-October 1989 series of very large SPEs) were measured in detail by Liulin active high sensitive dosimetric instrument installed on board MIR station. MIR station orbit measurements of the absorbed doses are compared with the interplanetary absorbed doses from SPEs estimated by the data obtained by the METEOR satellite spectrometer. The equivalent dose beyond the magnetosphere resulting from the September 29, 1989 solar flare in a spacecraft module with ordinary shielding thickness (approximately 10 g/cm2 of Al) is far higher than the maximum permissible dose of acute single exposure (50 cSv) and comparable with the maximum permissible dose of 2 year mission (118 cSv). Such large SPEs are a serious hazard in interplanetary missions and call forth of special administrative countermeasures.     

Variations of charged particle fluxes in the earth troposphere

The results of measurements of charged particles in the troposphere of polar and middle latitudes obtained since 1957 are presented. While in stratosphere the fluxes of secondary cosmic rays reproduce well the variations of primary cosmic radiation, mostly the 11-year cycle associated with solar activity, in troposphere other variations are added which are presumably of atmospheric origin. In particular, increased amplitudes of variations were observed before 1973 and after 1991. In the Northern hemisphere, the variations contain the annual wave with maximum in the winter period. The wave phase corresponds to the expected temperature effect, but in the 1990s its amplitude was several times larger than expected.