The combined effects of ionizing radiation and weightlessness on calcium and phosphorus content in the mineral fraction of the calcified tissues in the rat skeleton

Phosphorus and calcium content in the ash from skeletal bones (ribs, scapula, vertebra, and crus) of 30 rats exposed to ionizing radiation (800 rads) on the flight of the Kosmos 690 biosatellite was studied. A 10 percent decrease in ash content coefficient and 29 percent decrease in phosphorus content was found immediately after the flight, and a 9 percent decrease in phosphorus content persisted after 26 days of readaptation to terrestrial conditions

Absence of ferromagnetism in Co and Mn substituted polycrystalline ZnO

We discuss the properties of semiconducting bulk ZnO when substituted with the magnetic transition metal ions Mn and Co, with substituent fraction ranging from $x$ = 0.02 to $x$ = 0.15. The magnetic properties were measured as a function of magnetic field and temperature and we find no evidence for magnetic ordering in these systems down to $T$ = 2 K. The magnetization can be fit by the sum of a Curie-Weiss term with a Weiss temperature of $\Theta\gg$100 K and a Curie term. We attribute this behavior to contributions from both \textit{t}M ions with \textit{t}M nearest neighbors and from isolated spins. This particular functional form for the susceptibility is used to explain why no ordering is observed in \textit{t}M substituted ZnO samples despite the large values of the Weiss temperature. We also discuss in detail the methods we used to minimize any impurity contributions to the magnetic signal.Comment: 6 pages, 4 figures (revised

The effect of hypodynamia on mineral and protein metabolism in calcified tissues of the maxillodental system (experimental radioisotope study)

Mineral and protein metabolism was studied in experiments on 60 white rats, using P-32 and Ca-45 uptake in the mineral fractions, 2C-14-glycine in the protein fractions, and P-32 in both fractions of calcified tissues as indices over a 100 day period of experimental hypodynamia. Combined alterations in mineral and protein metabolism occurred in the calcified tissues of the experimental animals. The most pronounced changes were found in P-32 and 2C-14-glycine metabolism. In the incisors and femoral bones, these alterations occurred in two phases: P-32 and 2C-14-glycine uptake first increased, then decreased. Changes in Ca-45 metabolism were less pronounced, particularly in the initial period of the experiment. A marked reduction in P-32, Ca-45, and 2C-14-glycine uptake was found in various fractions of the calcified tissues on the 100th day of experimental hypodynamia

On the Thermal Instability in a Contracting Gas Cloud and Formation of a Bound Cluster

We perform linear analysis of thermal instability in a contracting large cloud filled with warm HI gas and investigate the effect of metallicity and radiation flux. When the cloud reaches critical density n_f, the cloud fragments into cool, dense condensations because of thermal instability. For a lower metallicity gas cloud, the value of n_f is high. Collision between condensations will produce self-gravitating clumps and stars thereafter. From the result of calculation, we suggest that high star formation efficiency and bound cluster formation are realized in low-metallicity and/or strong-radiation environments.Comment: 7 pages, including 7 figures, LaTeX2e(emulateapj5.sty) To appear in ApJ, Jun 10, 200

Effect of space flight on sodium, copper, manganese and magnesium content in the skeletal bones

Sodium content decreased in the human skeletal bones and rose in the rat bones following space flight. In man copper content rose in the femoral bone and decreased in the vertebral body and the sternum, but was unchanged in the rest of the bones. Magnesium content was decreased in the femoral bone and the sternum, and in the vertebrae, but remained unchanged in the rest of the bones. Possible mechanisms of the changes detected are discussed

Carrier-induced ferromagnetism in p-Zn1-xMnxTe

We present a systematic study of the ferromagnetic transition induced by the holes in nitrogen doped Zn1-xMnxTe epitaxial layers, with particular emphasis on the values of the Curie-Weiss temperature as a function of the carrier and spin concentrations. The data are obtained from thorough analyses of the results of magnetization, magnetoresistance and spin-dependent Hall effect measurements. The experimental findings compare favorably, without adjustable parameters, with the prediction of the Rudermann-Kittel-Kasuya-Yosida (RKKY) model or its continuous-medium limit, that is, the Zener model, provided that the presence of the competing antiferromagnetic spin-spin superexchange interaction is taken into account, and the complex structure of the valence band is properly incorporated into the calculation of the spin susceptibility of the hole liquid. In general terms, the findings demonstrate how the interplay between the ferromagnetic RKKY interaction, carrier localization, and intrinsic antiferromagnetic superexchange affects the ordering temperature and the saturation value of magnetization in magnetically and electrostatically disordered systems.Comment: 14 pages, 10 figure

A method of reconstruction after pancreaticoduodenectomy for pancreatic malignancies in very young children: Two cases reports

Pancreatic tumors are very rare diseases in very young children. Most information about those diseases in children was published in cases reports. Due to the rare nature of pancreatic tumors in children, there remains the absence of diagnostic algorithms, clear radiographic and morphological assessments as well as evidence based best treatment options. Because of the young age of patients and the rare occurrence of pancreatic neoplasms, tumor detection remains poor. For malignancies affecting the head of the pancreas the only possibility for achieving clear surgical margins is performing a pancreaticoduodenectomy (PD). We describe two cases of diagnostic and treatment of pancreatic tumor of very young children what was done in our institute

Carbon electronics and photonics

Diamond surpasses all known semiconductors in basic parameters, second only to gallium arsenide and graphene (a quasimetallic form of carbon) in electron mobility. For a long time, the widespread use of diamond in electronics was limited by the high cost and poor quality of both natural and synthetic raw materials. Currently, the technology of synthesis and doping of diamond has reached the necessary level for the breakthrough of diamond into electronics and photonics [1, 2]. In the first place, diamond based electronic devices will ensure long term and efficient operation in high temperature conditions and high levels of ionizing radiation, in the subterahertz frequency rang