[Structure of the metaepiphyseal growth plate cartilage in conditions of total isolation from cellular and humoral influences after its transplantation into soft tissues (an experimental study)].

The aim of this study was to determine the effect of a skeletal muscle on the cartilage of growth plate of metaepiphyseal explants of tubular bones of growing and mature Chinchilla rabbits (n = 18) under conditions of their isolation from cellular and humoral influences. In experimental animals, metaepiphyseal explants of metatarsal bones, containing growth plate, were sealed in polyethylene film and were placed, under local anesthesia, in the femoral muscles. One week later these grafts were removed and studied histologically. Despite the absence of the effects of biologically active substances and immunocompetent cells of the donor (foreign) organism, the exposure of the cartilage plate to the environment of the muscular tissue lead to some typical changes in its structure. The results obtained may indicate the susceptibility of the cartilage growth plates to the action of some distant factors, probably, of an electromagnetic nature. The detection of these factors is promising for the development of clinical methods of the stimulation of the damaged cartilage growth plates for the correction of bone deformities.

[Synthesis, structure, and biological properties of some 8alpha-analogues of steroid estrogens with fluorine in position 2].

A total synthesis of 8alpha analogues of steroid estrogens with fluorine in position 2 was achieved. Structural features of these compounds were studied by the example of 17beta-acetoxy-2-fluoro-3-methoxy-8alpha-estra-1,3,5(10)-triene. It was shown that the 8alpha analogues of 2-fluorosubstituted steroid estrogens have a low uterotropic activity and retain the osteoprotective and hypocholesterolemic activities.

Microdosimetric spectra and LET distributions on board the Mir space station obtained with a particle track detector.

A spectrometer measuring energy lost (deltaE) was used to determine linear energy transfer (LET) spectra on board the Mir orbital station during the period from 8 October 1997 to 16 June 2000, i.e. during the 24th, 26th, 27th and 28th basic expeditions. It was found that the LET spectra of secondary particles between 10 and 700 keV.microm(-1) in tissue do not depend on the external radiator, with the average quality factors for the region mentioned being about 6.4 with ICRP 26 quality factors or about 7.4 with ICRP 60 quality factors. Both differential and integral LET spectra are presented for some typical cases. The spectra permitted us to calculate the total doses and dose equivalents due to particles with the LET values in the mentioned region. It was found that these doses are higher when the detector was placed in a less shielded area. It was also found that these doses vary from one expedition to another. The correlation of these variations with the solar activity level was studied.

Why are the hydroxy groups of partially protected N-acetylglucosamine derivatives such poor glycosyl acceptors, and what can be done about it? A comparative study of the reactivity of N-acetyl-, N-phthalimido-, and 2-azido-2-deoxy-glucosamine derivatives in glycosylation. 2-Picolinyl ethers as reactivity-enhancing replacements for benzyl ethers.

Competition experiments were used to determine that the 4-OH of a 2-deoxy-2-azidoglucose derivative is more reactive than that of the corresponding N-phthalimido glucose derivative which, in turn, is more easily glycosylated than the N-acetyl derivative. Glycosylation of the 4-OH groups of the N,N-diacetyl and N-acetyl-N-benzyl glucosamine was also found to be superior to that of the simple N-acetyl substance. The 3-O-picolinyl ether of a 4,6-O-benzylidene-protected N-acetylglucosamine was shown to have a strong intramolecular hydrogen bond to the adjacent acetamide group. This interaction does not persist in the 3-O-picolinyl-6-O-benzyl N-acetylglucosamine derivative, owing to a probable competing hydrogen bond between the 4-OH and the picolinyl ether. However, in the 3-O-picolinyl-4-O-benzyl N-acetylglucosamine regioisomer the picolinyl-acetamide hydrogen bond persists and leads to an enhancement of reactivity of the 6-OH, over and above that in the corresponding 3-O-benzyl ether, due to disruption of the typical intermolecular amide hydrogen bonding scheme. It is demonstrated that the picolinyl ether is readily removed by hydrogenolysis at atmospheric pressure and room temperature.

Russian measurements of neutron energy spectra on the Mir orbital station.

Results of the experiments on neutron energy spectra measurements within broad energy range from 5 x 10(-7) to 2 x 10(2) MeV aboard the Mir orbital station and equivalent neutron dose estimation are presented. Four measurement techniques were used during the experiments. The shape of spectra and their absolute values are in good agreement. According to those experiments, an equivalent neutron dose depends upon effective shielding thickness and spacecraft mass. The neutron dose mentioned is comparable with that of ionizing radiation. Neutron flux levels measured aboard the Mir station have shown that a neutron spectrometer involving broad energy range will be used within the radiation monitoring systems in manned space flights.

Efficient, diastereoselective chemical synthesis of a beta-mannopyranosyl phosphoisoprenoid.

[reaction: see text] Tetrabutylammonium benzyl dihydrophytylphosphate was coupled to S-phenyl 2,3-di-O-benyl-4, 6-O-benzylidene-1-thio-alpha-D-mannopyranoside S-oxide on activation with triflic anhydride in toluene at -78 degrees C to give the corresponding beta-mannosyl phosphate in 56% yield with no detectable formation of the alpha-anomer. Treatment with sodium in liquid ammonia then afforded the unprotected beta-mannosyl phosphoisoprenoid.

Radiation measurements on the flight of IML-2.

The second flight of the International Microgravity Laboratory (IML-2) on Space Shuttle flight STS-65 provided a unique opportunity for the intercomparison of a wide variety of radiation measurement techniques. Although this was not a coordinated or planned campaign, by sheer chance, a number of space radiation experiments from several countries were flown on this mission. There were active radiation measuring instruments from Japan and US, and passive detectors from US, Russia, Japan, and Germany. These detectors were distributed throughout the Space Shuttle volume: payload bay, middeck, flight deck, and Spacelab. STS-65 was launched on July 8, 1994, in a 28.45 degrees x 306 km orbit for a duration of 14 d 17 hr and 55 min. The crew doses varied from 0.935 mGy to 1.235 mGy. A factor of two variation was observed between various passive detectors mounted inside the habitable Shuttle volume. There is reasonable agreement between the galactic cosmic ray dose, dose equivalent and LET spectra measured by the tissue equivalent proportional counter flown in the payload bay with model calculations. There are significant differences in the measurements of LET spectra measured by different groups. The neutron spectrum in the 1-20 MeV region was measured. Using fluence-dose conversion factors, the neutron dose and dose equivalent rates were 11 +/- 2.7 microGy/day and 95 +/- 23.5 microSv/day respectively. The average east-west asymmetry of trapped proton (>3OMeV) and (>60 MeV) dose rate was 3.3 and 1.9 respectively.

Some radiation environment estimation data from 10-12 km altitude aircraft.

The results of probing the radiation environment on board different civil aviation planes with single-type detectors (nuclear emulsions), with particular emphasis to the cosmic radiation flux measured in-side aircraft, are presented. The measurement results make it possible to find the absorbed and equivalent doses induced by the cosmic radiation neutrons and charged particles.

Intercomparison of radiation measurements on STS-63.

A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65 degrees inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 microGy with an average of 2265.8 microGy or 273.98 microGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 microGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 microGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 microGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1-20 MeV contributed 13 microGy/day and 156 microSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.

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.

Secondary radiations in spacecraft shieldings.

Some problems are discussed which relate to the generation of secondary radiation under the effects of heavy charged cosmic ray particles in spacecraft shielding and in biological tissue. Methods for obtaining the total and differential inelastic interaction cross sections are recommended for use in the calculation of heavy charged particle transport in the shielding. The most extensively used methods for calculating heavy charged particle passage through matter are appraised. The results of calculating cosmic ray doses in biological tissue behind shielding, which allow for the secondary particle contribution, are presented. All the calculations have been made using the set of radiation protection standards approved by the Russian State Committee for Standards. The set of standards has been verified experimentally on board satellites of the Cosmos series.

Multiplicities of secondaries in nuclear interactions, induced by 20Ne, 40Ar and 56Fe nuclei at 0.1-0.5 GeV/nucleon.

Multiplicities of various species of charged secondaries produced in inelastic interactions of 20Ne, 40Ar and 56Fe nuclei with emulsion nuclei at 0.1-0.5 GeV/nucleon have been measured. The data obtained are compared with the results for interactions of higher energy nuclei with emulsion nuclei. The dependences of the nucleus-nucleus interaction parameters on masses and energies of colliding nuclei are examined.

Dependence of the multiplicities of secondary particles on the impact parameter in collisions of high-energy neon and iron nuclei with photoemulsion nuclei.

A method is proposed for finding the dependence of mean multiplicities of secondaries on the nucleus-collision impact parameter from the data on the total interaction ensemble. The impact parameter has been shown to completely define the mean characteristics of an individual interaction event. A difference has been found between experimental results and the data calculated in terms of the cascade-evaporation model at impact-parameter values below 3 fm.

Neutron fluences and energy spectra in the Cosmos-2044 biosatellite orbit.

Joint Soviet-American measurements of the neutron component of space radiation (SR) were carried out during the flight of the Soviet biosatellite Cosmos-2044. Neutron flux densities and differential energy spectra were measured inside and on the external surface of the spacecraft. Three energy intervals were employed: thermal (En < or = 0.2 eV), resonance (0.2 eV < En < 1.0 MeV) and fast (En > or = 1.0 MeV) neutrons. The first two groups were measured with U.S. 6LiF detectors, while fast neutrons were recorded both by U.S. fission foils and Soviet nuclear emulsions. Estimations were made of the contributions to absorbed and equivalent doses from each neutron energy interval and a correlation was presented between fast neutron fluxes, measured outside the satellite, and the phase of solar activity (SA). Average dose equivalent rates of 0.018 and 0.14 mrem d-1 were measured for thermal and resonance neutrons, respectively, outside the spacecraft. The corresponding values for fast neutrons were 3.3 (U.S.) and 1.8 (U.S.S.R.) mrem d-1. Inside the spacecraft, a value of 3.5 mrem d-1 was found.

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.

Cosmic ray LET spectra and doses on board Cosmos-2044 biosatellite.

Results of the experiments on board Cosmos-2044 (Biosatellite 9) are presented. Various nuclear track detectors (NTD) (dielectric, AgCl-based, nuclear emulsions) were used to obtain the LET spectra inside and outside the satellite. The spectra from the different NTDs have proved to be in general agreement. The results of LET spectra calculations using two different models are also presented. The resultant LET distributions are used to calculate the absorbed and equivalent doses and the orbit-averaged quality factors (QF) of the cosmic rays (CR). Absorbed dose rates inside (approximately 20 g cm-2 shielding) and outside (1 g cm-2) the spacecraft, omitting electrons, were found to be 4.8 and 8.6 mrad d-1, respectively, while the corresponding equivalent doses were 8.8 and 19.7 mrem d-1. The effects of the flight parameters on the total fluence of, and on the dose from, the CR particles are analyzed. Integral dose distributions of the detected particles are also determined. The LET values which separate absorbed and equivalent doses into 50% intervals are estimated. The CR-39 dielectric NTD is shown to detect 20-30% of the absorbed dose and 60-70% of the equivalent dose in the Cosmos-2044 orbit. The influence of solar activity phase on the magnitude of CR flux is discussed.

Radiation shielding estimates for manned Mars space flight.

In the analysis of the required radiation shielding protection of spacecraft during a Mars flight, specific effects of solar activity (SA) on the intensity of galactic and solar cosmic rays were taken into consideration. Three spaceflight periods were considered: (1) maximum SA; (2) minimum SA; and (3) intermediate SA, when intensities of both galactic and solar cosmic rays are moderately high. Scenarios of spaceflights utilizing liquid-propellant rocket engines, low- and intermediate-thrust nuclear electrojet engines, and nuclear rocket engines, all of which have been designed in the Soviet Union, are reviewed. Calculations were performed on the basis of a set of standards for radiation protection approved by the U.S.S.R. State Committee for Standards. It was found that the lowest estimated mass of a Mars spacecraft, including the radiation shielding mass, obtained using a combination of a liquid propellant engine with low and intermediate thrust nuclear electrojet engines, would be 500-550 metric tons.

Target fragments in collisions of 1.8 GeV/nucleon 56Fe nuclei with photoemulsion nuclei, and the cascade-evaporation model.

Nuclear photographic emulsion is used to study the dependence of the characteristics of target-nucleus fragments on the masses and impact parameters of interacting nuclei. The data obtained are compared in all details with the calculation results made in terms of the Dubna version of the cascade-evaporation model (DCM).

Multiplicities of secondaries in interactions of 1.8 GeV/nucleon 56Fe nuclei with photoemulsion and the cascade evaporation model.

A nuclear photographic emulsion method was used to study the charge-state, ionization, and angular characteristics of secondaries produced in inelastic interactions of 56Fe nuclei at 1.8 GeV/nucleon with H, CNO, and AgBr nuclei. The data obtained are compared with the results of calculations made in terms of the Dubna version of the cascade evaporation model (DCM). The DCM has been shown to satisfactorily describe most of the interaction characteristics for two nuclei in the studied reactions. At the same time, quantitative differences are observed in some cases.

Depth distribution of absorbed dose on the external surface of Cosmos 1887 biosatellite.

Significant absorbed dose levels exceeding 1.0 Gy day-1 have been measured on the external surface of the Cosmos 1887 biosatellite as functions of depth in stacks of thin thermoluminescent detectors (TLDs) of U.S.S.R. and U.S.A. manufacture. The dose was found to decrease rapidly with increasing absorber thickness, thereby indicating the presence of intensive fluxes of low-energy particles. Comparison between the U.S.S.R. and U.S.A. results and calculations based on the Vette Model environment are in satisfactory agreement. The major contribution to the dose under thin shielding thickness is shown to be from electrons. The fraction of the dose due to protons and heavier charged particles increases with shielding thickness.