Disorder-driven transition to tubular phase in anisotropic two-dimensional materials

We develop a theory of anomalous elasticity in disordered two-dimensional flexible materials with orthorhombic crystal symmetry. Similar to the clean case, we predict existence of infinitely many flat phases with anisotropic bending rigidity and Young's modulus showing power-law scaling with momentum controlled by a single universal exponent the very same as in the clean isotropic case. With increase of temperature or disorder these flat phases undergo crumpling transition. Remarkably, in contrast to the isotropic materials where crumpling occurs in all spatial directions simultaneously, the anisotropic materials crumple into tubular phase. In distinction to clean case in which crumpling transition happens at unphysically high temperatures, a disorder-induced tubular crumpled phase can exist even at room-temperature conditions. Our results are applied to anisotropic atomic single layers doped by adatoms or disordered by heavy ions bombarding.Comment: 18 LaTex pages, 6 figure

Thermoelectric performance of weakly coupled granular materials

We study thermoelectric properties of inhomogeneous nanogranular materials for weak tunneling conductance between the grains, g_t < 1. We calculate the thermopower and figure of merit taking into account the shift of the chemical potential and the asymmetry of the density of states in the vicinity of the Fermi surface. We show that the weak coupling between the grains leads to a high thermopower and low thermal conductivity resulting in relatively high values of the figure of merit on the order of one. We estimate the temperature at which the figure of merit has its maximum value for two- and three-dimensional samples. Our results are applicable for many emerging materials, including artificially self-assembled nanoparticle arrays.Comment: 4 pages, 3 figure

Germination of pine seed in weightlessness (investigation in Kosmos 782)

An investigation was made of the orientation of aboveground and underground organs of pine plants grown from seed in weightlessness. Orientation was found to be caused by the position of the seeds relative to the substrate surface. Normal growth was manifest only for the plants grown from seed oriented with embryo toward the substrate. Differences were noted between experiment and control as to the quantitative content of nucleoli in the meristematic cells of the rootlets and the shape of cells in the cotyledonous leaflets. No complete agreement was found between data obtained in weightlessness and when gravity was compensated (clinostat treatment with horizontal rotation)

Thermoelectric performance of granular semiconductors

We study thermoelectric properties of granular semiconductors with weak tunneling conductance between the grains, g_t < 1. We calculate the thermopower and figure of merit taking into account the shift of the chemical potential and the asymmetry of the density of states in the vicinity of the Fermi surface due to n- or p-type doping in the Efros-Shklovskii regime for temperatures less than the charging energy. We show that for weakly coupled semiconducting grains the figure of merit is optimized for grain sizes of order 5nm for typical materials and its values can be larger than one. We also study the case of compensated granular semiconductors and show that in this case the thermopower can be still finite, although two to three orders of magnitude smaller than in the uncompensated regime.Comment: 4 pages, 4 figure

Pine seed germination under weightlessness (a study of the Kosmos 782 satellite)

Orientation of the above and underground organs of pine plants, grown from seeds under weightlessness, was found to be determined by seed position on the substrate. Normal plant growth was observed only if the seed embryos were oriented toward the substrate. Some differences were noted between the experimental and control plants concerning the amount of nucleoli in the root meristematic cells and the cell shape in cotyledonous leaves. No complete similarity was found in experimental results obtained with plants under weightlessness and under compensated gravity. The seeds were obtained from Pinus silvestris, considered to be particularly suitable for this experiment

Regression in the Symptoms and Discal Hernia in Case of Lumbar Radiculopathy

BACKGROUND: Discogenic lumbar radiculopathy has a favorable potential for survival; the regression of clinical symptoms may outpace the subsidence of discal hernia. AIM: The objective of the study is comparing the clinical data and the results of magnetic resonance imaging (MRI) in patients with discogenic lumbar radiculopathy over 1 year of observation. MATERIALS AND METHODS: Thirty-two patients (13 males at the average age of 39.1 ± 11.8 years) with discogenic lumbar radiculopathy confirmed by MRI were examined in the study. The intensity of pain condition was assessed using the numerical rating scale; disability was assessed using the Oswestry disability index. Sixteen patients were subjected to repeated MRI. RESULTS: Statistically significant (p &lt; 0.01) reduction of the average pain intensity and intensity of disability more than 2 times was observed as early as in the first 2 weeks. Gradual reduction of pain and disability was observed during the year. Reduction of discal hernia by more than 50% was observed on average after 8.7 ± 4.7 months. CONCLUSION: In the case of discogenic radiculopathy, the reduction of pain and related disability far outstrips the regression of the herniation of intervertebral disk

Electrical properties of polyurethane metal complexes

The static and dynamic electrical conductivity of coordination compounds of 2, 4-tolylene diisocyanate with Cu (II) and Fe (II) halides, and also polyurethanes synthesized from them are studied. According to the proposed model, the electrical conductivity of metal coordination polyurethanes is associated with electron exchange bettween metal ions of different valence, and depends on saturation with electrons of hetero-atoms entering into the composition of the flexible parts of the macro-chain. © 1990