Upper critical field, pressure-dependent superconductivity and electronic anisotropy of Sm4Fe2As2Te(1-x)O(4-y)F(y).

We present a detailed study of the electrical transport properties of a recently discovered iron-based superconductor: Sm4Fe2As2Te0.72O2.8F1.2. We followed the temperature dependence of the upper critical field by resistivity measurement of single crystals in magnetic fields up to 16 T, oriented along the two main crystallographic directions. This material exhibits a zero-temperature upper critical field of 90 T and 65 T parallel and perpendicular to the Fe2As2 planes, respectively. An unprecedented superconducting magnetic anisotropy γH=H(c2)(ab)/H(c2)(c) ~ 14 is observed near Tc, and it decreases at lower temperatures as expected in multiband superconductors. Direct measurement of the electronic anisotropy was performed on microfabricated samples, showing a value of ρ(c)/ρ(ab)(300K) ~ 5 that rises up to 19 near Tc . Finally, we have studied the pressure and temperature dependence of the in-plane resistivity. The critical temperature decreases linearly upon application of hydrostatic pressure (up to 2 GPa) similarly to overdoped cuprate superconductors. The resistivity shows saturation at high temperatures, suggesting that the material approaches the Mott-Ioffe-Regel limit for metallic conduction. Indeed, we have successfully modelled the resistivity in the normal state with a parallel resistor model that is widely accepted for this state. All the measured quantities suggest strong pressure dependence of the density of states.

Ultrasensitive 1D field-effect phototransistors: CH3NH3PbI3 nanowire sensitized individual carbon nanotubes.

Field-effect phototransistors were fabricated based on individual carbon nanotubes (CNTs) sensitized by CH3NH3PbI3 nanowires (MAPbI3NWs). These devices represent light responsivities of R = 7.7 × 10(5) A W(-1) under low-lighting conditions in the nW mm(-2) range, unprecedented among CNT-based photodetectors. At high incident power (∼1 mW mm(-2)), light soaking results in a negative photocurrent, turning the device insulating. We interpret the phenomenon as a result of efficient free photoexcited charge generation and charge transfer of photoexcited holes from the perovskite to the carbon nanotube. The charge transfer improves conductance by increasing the number of carriers, but leaves electrons behind. At high illumination intensity their random electrostatic potential quenches mobility in the nanotube.

Structural characterization of eutectic aqueous NaCl solutions under variable temperature and pressure conditions.

The structure of amorphous NaCl solutions produced by fast quenching is studied as a function of pressure, up to 4 GPa, by combined neutron diffraction experiments and classical molecular dynamics simulations. Similarly to LiCl solutions the system amorphizes at ambient pressure in a dense phase structurally similar to the e-HDA phase in pure water. The measurement of the static structure factor as a function of pressure allowed us to validate a new polarizable force field developed by Tazi et al., 2012, never tested under non-ambient conditions. We infer from simulations that the hydration shells of Na(+) cations form well defined octahedra composed of both H2O molecules and Cl(-) anions at low pressure. These octahedra are gradually broken by the seventh neighbour moving into the shell of first neighbours yielding an irregular geometry. In contrast to LiCl solutions and pure water, the system does not show a polyamorphic transition under pressure. This confirms that the existence of polyamorphism relies on the tetrahedral structure of water molecules, which is broken here.

Separation of orbital contributions to the optical conductivity of BaVS(3).

The correlation-driven metal-insulator transition (MIT) of BaVS(3) was studied by polarized infrared spectroscopy. In the metallic state two types of electrons coexist at the Fermi energy: the quasi-1D metallic transport of A(1g) electrons is superimposed on the isotropic hopping conduction of localized E(g) electrons. The "bad-metal" character and the weak anisotropy are the consequences of the large effective mass m(eff) approximately 7 m(e) and scattering rate Gamma > or = 160 meV of the quasiparticles in the A(1g) band. There is a pseudogap above T(MI) = 69 K, and in the insulating phase the gap follows the BCS-like temperature dependence of the structural order parameter with Delta(ch) approximately 42 meV in the ground state. The MIT is described in terms of a weakly coupled two-band model.

Charge dynamics of 2H- TaSe2 along the less-conducting c-axis.

We present an optical study of 2H-TaSe2 along the less conducting c-axis. This dichalcogenide compound belongs to a large class of conductors called "bad metals" (with a mean free path smaller than the lattice constant along the c-axis), which also includes the superconducting cuprates. The optical response shows the progressive development of a pseudogaplike feature with decreasing temperature. The spectral weight lost by the opening of such a pseudogap goes into the narrow Drude component, developing at low frequency and temperature. There is no violation of the sum rule in 2H-TaSe2 contrary to the cuprates.

Pressure induced quantum critical point and non-fermi-liquid behavior in BaVS3

The phase diagram of BaVS3 is studied under pressure using resistivity measurements. The temperature of the metal to nonmagnetic Mott insulator transition decreases under pressure, and vanishes at the quantum critical point p(cr) = 20 kbar. We find two kinds of anomalous conducting states. The high-pressure metallic phase is a non-Fermi liquid described by Deltarho approximately T(n) where n = 1.2-1.3 at 1

Heteromorphic grade of renal cell cancer.

The present study demonstrates by means of histopathologic analysis that most of the renal adenocarcinomas are microscopically heterogeneous--named by authors as heteromorphic. This heteromorphism means the mixture of different cell types, histological patterns and fields of tumor with different nuclear atypia. 300 surgical specimens of renal cell cancer (RCC) were reclassified retrospectively. The histologic classification was as follows: 1. Nuclear atypia (nuclear grading according to Skinner); 2. Histological structure (compact, tubular, papillary, cystic); 3. Tumor cell types (clear, chromophobe, chromophilic basophilic, chromophilic eosinophilic). Homogeneous tumors consist of the three categories of this basic classifications. Heteromorphic tumors have combinations the three categories: different cell types (clear and granular) and/or histological elements (tubulo-papillary) and/or nuclear structure. Heteromorphism of RCC can be graded as: G-I: homogeneous structure (three patterns, one-one pattern of the three categories; G-II: 3 + 1 patterns.... G-III: 3 + 2 patterns.... G-IV: 3 + 3 or more patterns of the classification given above. This grading system is recommended for the heteromorphism of renal adenocarcinomas.

Wheelchair rider injuries: causes and consequences for wheelchair design and selection.

An understanding of adverse incidents and injuries sustained by active wheelchair riders, who live and work in the mainstream of society, is needed to improve safety via wheelchair design, selection, and configuration. We interviewed 109 riders who had experienced incidents, in order to identify the causes of incidents and injuries they suffered. Participants reported n = 253 incidents (53% in powered wheelchairs, 47% manual) occurring within a 5-year period, comprised of 106 (42%) "Tips and Falls," 84 (33%) "Component Failures," and 63 (25%) "Other" events. Sixty-eight (27%) of the incidents caused injuries requiring medical attention, including 13 hospitalizations. Direction of Tips and Falls was associated with wheelchair type (manual or powered) and with different riding surfaces. Aspects of wheelchair stability, particularly the effects of wheelchair configuration and of different riding surfaces, are important engineering issues affecting wheelchair safety. Interpretation of the results highlights wheelchair stability mechanics. Potential design improvements are discussed.

Use of the Cardiff infusor for induction of labour in a metropolitan maternity unit.

Use of the Cardiff infusor was studied over a 3-year period at Manly District Hospital to assess its advantages in relation to labour parameters and gross effects on the newborn infant.