The thermodynamic properties of liquid binary mixtures of <Emphasis Type="Italic">n</Emphasis>-alkanes: <Emphasis Type="Italic">n</Emphasis>-decane + <Emphasis Type="Italic">n</Emphasis>-hexadecane

Data on sound velocity are used for determining the density, the isobaric expansion coefficient, the isobaric and isochoric heat capacity, and the isothermal compressibility of liquid binary mixture of n-decane + n-hexadecane of three compositions in the temperature range of 298–433 K and pressure range of 0.1–100 MPa. The coefficients of Tait equation are calculated in the above-identified range of parameters. The calculation results are compared with experimental data on density. The divergence does not exceed 0.2% for the most reliable data.     

The Viscosity and Density of <Emphasis Type="Italic">n</Emphasis>-Dodecane and <Emphasis Type="Italic">n</Emphasis>-Octadecane at Pressures up to 200 MPa and Temperatures up to 473 K

A vibrating-wire instrument for simultaneous measurement of the density and viscosity of liquids under conditions of high pressure is described. The instrument is capable of operation at temperatures between 298.15 and 473.15 K at pressures up to 200 MPa. Calibration was performed by means of measurements in vacuum, air, and toluene at 298.15 K. For n-dodecane measurements were made along eight isotherms between 298.15 and 473.15 K at pressures up to 200 MPa while for n-octadecane measurements were measured along seven isotherms between 323.15 and 473.15 K at pressures up to 90 MPa. The estimated uncertainty of the results is 2% in viscosity and 0.2% in density. Comparisons with literature data are presented.     

Electrical characteristics of (<Emphasis Type="Italic">p</Emphasis>)3C-SiC-(<Emphasis Type="Italic">n</Emphasis>)6H-SiC heterojunctions

The electrical characteristics of (p)3C-SiC-(n)6H-SiC epitaxial heterostructures obtained by sublimation epitaxy in vacuum are studied. The band discontinuities are determined and the energy band diagram of the heterojunction is constructed. It is shown that the obtained heterostructure offers a promising material for high electron mobility transistors.     

A Statistical Model of <Emphasis Type="Italic">I</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> Changes for Bending Bi-2223 Tapes

Bi-2223 tape was one of the high-temperature superconductors with commercial applications. One of the applications was bending and winding Bi-2223 tape into solenoids to produce high magnetic fields. To study bending properties, three multifilamentary of Bi-2223 tapes sheathed with silver alloys were manufactured. Bending experiments for the tapes were performed, and critical currents I _c of tapes with definite bending radius were measured. And, current transferring mechanisms in filaments were analyzed, as well. Experimental results showed that silver alloy sheathed tapes had better bending properties than pure silver-sheathed one. On the contrary, to describe bending radius dependence of I _c , a statistical model was suggested. The model expected that bending radius dependence of I _c was following an exponential law that was quantitatively expressed by mathematic expressions. Bending dependence of I _c could be calculated from the expression and calculated results agreed with experimental data very well. Therefore, the suggested model has successfully explained the experimental results.     

Viscosity and Surface Tension of Saturated <Emphasis Type="Italic">n</Emphasis>-Pentane

Light scattering by thermally excited capillary waves on liquid surfaces or interfaces can be used for the investigation of viscoelastic properties of fluids. In this work, the simultaneous determination of surface tension and liquid kinematic viscosity of n-pentane by surface light scattering (SLS) on a gas–liquid interface was carried out. The experiments are based on a heterodyne detection scheme and signal analysis by photon correlation spectroscopy (PCS). Measurements were performed under saturation conditions over a wide temperature range from about 233 to 363 K. For the whole temperature range the total uncertainty of the liquid kinematic viscosity and surface tension is estimated to be better than 1.0 and 1.2, respectively. The results obtained corroborate the reliability of the SLS technique for the determination of thermophysical properties.     

Magneto-Peltier cooling of single-crystal Bi<Subscript>1-<Emphasis Type="Italic">X</Emphasis></Subscript>Sb<Subscript><Emphasis Type="Italic">X</Emphasis></Subscript> (<Emphasis Type="Italic">X </Emphasis>= 0.12 and 0.15) alloys

The cooling temperatures of rectangular parallelepiped Bi_1-X Sb _X (X = 0.12 and 0.15) single-crystals with the same thickness of t = 2 mm but different width W were measured at 113 K and 290 K as a function of electric current in the magnetic field B up to 2.17 T. The magnetic field was aligned along the thickness t of a sample and the current flows along its length L through the copper leads soldered to both end surfaces of cross section (W × t), where W, t and L are parallel to the binary, bisector and trigonal axes of the single-crystal, respectively. The thermoelement was not in contact with a heat sink. The cooling temperature of Bi_0.85Sb_0.15 at 290 K was increased with an increase of B and was almost symmetric for the reverse of the field direction, while at 113 K it exhibited a maximum at B = ±0.25 T and a strong asymmetry for the field direction. The largest maximum cooling temperature ΔT _max of Bi_0.85Sb_0.15 was achieved when a thermoelement has optimum dimensions so that heat energy is hardly generated at the cold side. When the single-crystal Bi_0.85Sb_0.15 alloy has optimum dimensions of L = 15 mm, W = 4 mm and t = 2 mm, the ΔT _max at 290 K increased from 4.2 K in B = 0 T to 9.6 K in B = +2.17 T, so that it exceeded ΔT _max values of 5.7 K obtained for a typical Bi₂Te₃ and 8.5 K measured previously for Bi single-crystal in B = +2.17 T.     

Asymmetric current transfer in isotype <Emphasis Type="Italic">n</Emphasis>-In<Subscript>2</Subscript>Se<Subscript>3</Subscript>/<Emphasis Type="Italic">n</Emphasis>-InSe heterocontacts

We have studied the mechanisms of current transfer and the capacitance-voltage characteristics of a radiation-resistant isotype n-In₂Se₃/n-InSe heterocontact in which the region depleted of major charge carriers is localized predominantly in a relatively low-ohmic semiconductor—the α-type In₂Se₃ with a large density of defects. The spectrum of the relative quantum efficiency of photoconversion in this structure depends on the thickness of the In₂Se₃ layer and on the geometry of illumination of the heterocontact.     

Sensitivity of dislocation engineered Si <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">n</Emphasis> junctions to influence of illumination and ultrasound

In this work it is shown that the dislocation engineered Si p-n junctions are sensitive to variations of illumination intensity. It is found that with the aim of ultrasound processing it is possible to purposefully modulate properties of the device structure.     

Generalization of <Emphasis Type="Italic">T</Emphasis> and <Emphasis Type="Italic">A</Emphasis> integrals to time-dependent materials: analytical formulations

This paper deals with the generalization of T-integral to crack growth process in viscoelastic materials. In order to implement this expression in a finite element software, a modelling form of this integral, called Aθ, is developed. The analytical formulation is based on conservative law, independent path integral, and a combination of real, virtual displacement fields, and real, virtual thermal fields introducing, in the same time, a bilinear form of free energy density F. According to the generalization of Noether’s method, the application of Gauss Ostrogradski’s theorem combined with curvilinear cracked contour, T _v is obtained. By introducing a volume domain around crack tip, the modelling expression Aθ is also defined.. Finally, the viscoelastic generalization through a thermodynamic approach, called A _v , is introduced by using a discretisation of the creep tensor according to a generalized Kelvin Voigt representation.     

Preparation and Mechanical Properties of Carbon Fiber Reinforced (BC<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>–SiC)<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> Multilayered Matrix Composites

A boron doped carbon materials (BC _x ) was prepared by chemical vapor deposition and a 3D (BC _x –SiC) _n multilayered matrix composite reinforced by carbon fiber, C/(BC _x –SiC) _n , was prepared by chemical vapor infiltration (CVI). XPS and SEM results showed that the BC _x matrix had a boron content of 15 at.% and exhibited a very finely laminated structure. XRD analysis showed the BC _x matrix was mainly carbon with B₄C crystals in it. SEM and EDS results showed that the BC _x layers and the SiC layers were deposited within the interspaces of fiber bundles, alternately arranged and paralleled to each other as designed. The fracture energy of the composite was about 16.8 KJ m⁻². Flexural strength–displacement curve showed a remarkable metal-like yielding stage. Multiple fracture microstructures were induced by the multilayered matrix, such as delaminations of the multilayered matrix, deflections and propagations of cracks spread in the multilayered matrix layer by layer and long pullout of fiber bundles together with fiber clusters with multi-step pull-out structures. It was suggested that these special fracture behaviors absorbed a great deal of energy during the stress increasing and released the stress concentration, in this way, the toughness of the materials was improved.     

Combination of <Emphasis Type="Italic">Eigenfactor</Emphasis><Superscript>TM</Superscript> and <Emphasis Type="Italic">h-</Emphasis>index to evaluate scientific journals

The h-index and Eigenfactor ^TM values of top and specialized scientific/engineering journals are tabulated and combined to provide a simple graphical representation of the journals. The information may be tailored to specific uses by respective stakeholders to aid decision making processes with regards to scholarly research and scientific journal publications.     

Electrical properties of photodiodes based on <Emphasis Type="Italic">p</Emphasis>-GaSb/<Emphasis Type="Italic">p</Emphasis>-GaInAsSb/<Emphasis Type="Italic">N</Emphasis>-GaAlAsSb heterojunctions

We have studied the electrical characteristics of photodiodes based on p-GaSb/p-GaInAsSb/N-GaAlAsSb heterojunctions and investigated the mechanisms of current transfer in these heterostructures at various temperatures. A comparison of the theoretical results and experimental data showed that the tunneling charge transfer mechanism dominates at low temperatures (T < 150 K) under both forward and reverse bias conditions. The tunneling current becomes a determining factor at an electric field strength in the p-n junction of no less that 10⁵ V/cm, which is related to a small bandgap width of the materials studied and low effective masses of electrons and holes.     

<Emphasis Type="Italic">hg</Emphasis>-index: a new index to characterize the scientific output of researchers based on the <Emphasis Type="Italic">h</Emphasis>- and <Emphasis Type="Italic">g</Emphasis>-indices

To be able to measure the scientific output of researchers is an increasingly important task to support research assessment decisions. To do so, we can find several different measures and indices in the literature. Recently, the h-index, introduced by Hirsch in 2005, has got a lot of attention from the scientific community for its good properties to measure the scientific production of researchers. Additionally, several different indicators, for example, the g-index, have been developed to try to improve the possible drawbacks of the h-index. In this paper we present a new index, called hg-index, to characterize the scientific output of researchers which is based on both h-index and g-index to try to keep the advantages of both measures as well as to minimize their disadvantages.     

Electrical conductivity of homopolymer and copolymers of <Emphasis Type="Italic">N</Emphasis>-vinylcarbazole

Poly(N-vinylcarbazole) (PVCz) is well known as an electroactive material due to its good photoconductivity, charge-transfer complexes, photoluminescence and electroluminescence properties. The block copolymers of N-vinylcarbazole were prepared and the effects of the relative composition, molar masses, architecture and doping on its electrical behavior were investigated. Controlled free radical polymerization has been carried out using nitroxide-mediated process in order to prepare a series of block copolymers of N-vinylcarbazole. 2,2,6,6-Tetramethyl-1-piperidinyloxy radical (TEMPO) was used to end-cap “living” homopolymer of p-bromostyrene, which was further used as a macroinitiator to polymerize N-vinylcarbazole and styrene. The copolymers have been doped at room temperature with LiClO₄ and the electrical conductivities were measured by two-probe method, which have shown to depend on copolymer’s relative composition and molar masses.     

Optical,structural and electrical investigations on PbTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>S<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> alloys

The fabrication of devices with lead salts and their alloys with detecting and lasing capabilities has been an important technological development. The high quality polycrystalline thin films of PbTe_1−x S _x with variable composition (0 ≤ x ≤ 1) have been deposited onto ultra clean glass substrates by vacuum evaporation technique. Optical, structural and electrical properties of PbTe_1−x S _x thin films have been examined. Absorption coefficient and band gap of the films were determined by absorbance measurements in wavelength range 2,500–5,000 nm using FTIR spectrophotometer. Sample nature, crystal structure and lattice parameter of the films were determined from X-ray diffraction patterns. DC conductivity and activation energy of the films were measured in temperature range 300–380 K through I–V measurements.     

Gravireception in <Emphasis Type="Italic">Phycomyces Blakesleeanus</Emphasis> and <Emphasis Type="Italic">Arabidopsis Thaliana</Emphasis>: Hysteretic Behavior of Primary Reactions

The gravireception of the fungus Phycomyces blakesleeanus and seedlings of Arabidopsis thaliana is accompanied by gravity-induced absorption changes (GIACs) that occur very fast and most likely represent primary responses of gravireception. GIACs that were analyzed during parabolic flights in micro- and hypergravity invariably display hysteretic behavior. Even though the identity of the pigments generating the GIACs remain presently unknown, it is nevertheless clear that they are specific for gravireception. This is strongly suggested by the fact that hystereses loops of wild-type specimen are significant larger than of gravitropic mutants. Hystereses are largely kinetically determined, are specific for the different organisms and stimulus programs, and thus aid in characterizing the requisite transduction chains of gravireception. The fact that monocot as well as dicot plants display GIACs just in the area of highest gravitropic sensitivity at the tip supports the conclusion that gravireception is generally associated with primary reactions.     

Nuclear-Physical Properties of <Superscript>105, 106<Emphasis Type="Italic">m</Emphasis>, 110<Emphasis Type="Italic">m</Emphasis></Superscript>Ag

The nuclear-physical properties of the nuclides ^{105, 106m,110m} Ag, which are concomitant nuclides in reactor production of ¹⁰³Pd and ¹⁰⁹Cd used in metrology of ionizing radiations and in nuclear medicine, were studied. The following quantities were determined by semiconductor X-ray and γ-ray spectrometry: the parameter K _α/K _β of X-ray K radiation accompanying the decay of ^110m Ag and the intensities of γ-ray quanta with the energies of 280 and 345 keV (¹⁰⁵Ag); 430, 451, and 512 keV (^106m Ag); 658, 764, 885, 938, and 1384 keV (^110m Ag). The half-lives determined using the above γ-ray lines are as follows: T _1/2(¹⁰⁵Ag) = 41.2 ± 0.1 days; T _1/2(^106m Ag) = 8.30±0.07 days. The errors are given for 95% confidence level.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 31–34.Original Russian Text Copyright © 2005 by Popov, Zakharova, Sadulin, Andreev, Pakhomov.     

Application of a sensitivity equation method to the <Emphasis Type="Italic">k</Emphasis>–<Emphasis Type="Italic">ε</Emphasis> model of turbulence

In this paper, we present some examples of sensitivity analysis for flows modeled by the standard k–ε model of turbulence with wall functions. The flow and continuous sensitivity equations are solved using an adaptive finite element method. Our examples emphasize a number of applications of sensitivity analysis: identification of the most significant parameters, analysis of the flow model, assessing the influence of closure coefficients, calculation of nearby flows, and uncertainty analysis. The sensitivity parameters considered are closure coefficients of the turbulence model and constants appearing in the wall functions.     

Detecting quasi-periodic {11<Emphasis Type="Italic">n</Emphasis>} (<Emphasis Type="Italic">n</Emphasis> = 7–11) faces in samples with Ge/Si quantum dots by grazing X-ray reflectometry

High-resolution grazing X-ray reflectometry is used to obtain experimental and theoretical data on the intensity of specular and diffuse reflection from self-organized structures grown by molecular beam epitaxy with single-layer (non-overgrown) and multilayer (overgrown) Ge/Si quantum dots (QDs). Using the positions of diffuse scattering peaks in the direct space, the slopes of quasi-periodic faces have been determined to within ±0.1° by a method employed previously for the investigation of In(Ga)As/GaAs quantum dots. Finding the quasi-periodic {11n} (n = 7−11) faces (typical of the growth of ordered QDs) in the samples with disordered Ge/Si quantum dots is evidence of the generality of mechanisms of QD formation in different systems.     

Electrical impedance of ethylene-carbon monoxide/propylene-carbon monoxide (<Emphasis Type="Italic">EPEC</Emphasis>-<Emphasis Type="Italic">69</Emphasis>) thermoplastic polyketone

Electrical impedance technique was employed to investigate the electrical properties of ethylene-carbon monoxide/propylene-carbon monoxide terpolymer (EPEC-69). The measurements were performed in the frequency range 0.1–10⁵ Hz and in the temperature range 30–110 °C. The results reveal that the dielectric constant, loss factor, modulus, and ac conductivity are dependent of frequency and temperature. A Debye relaxation peak was detected in the plot of Z″ versus frequency where the activation energy was determined and found to be 1.26 eV. When the surface phenomenon effects were separated using the imaginary part of the complex admittance a second dielectric dispersion was observed in the low frequency region. Two models were proposed from the impedance measurements depending on temperature range.