Energy of formation for and liquid binary alloys

We have investigated the free energy of formation for Ag_xIn_1-x and Ag_xSn_1-x liquid binary alloys at temperatures 1173 and 1250 K, respectively. A microscopic theory based on the first order perturbation has been applied. The interionic interaction and a reference liquid are the fundamental components of the theory. The interionic interaction is described by a local pseudopotential. A liquid of hard spheres (HS) of two different effective diametres and charges is used to describe the reference system. The results of the calculations for energy of formation agree very well with the available experimental data. Our calculations also reveal that a simple perturbative approach along with appropriate effective pair potentials can produce nearly quantitative results for the concerned alloys.     

Comparative analysis of refrigerant performance between LPG and R134a under subtropical climate

Journal of Thermal Analysis and Calorimetry - In this investigation, a series of experiments were conducted to explore the effects of liquefied petroleum gas (LPG) mixture of 60% propane and 40%...     

In Vivo Imaging of the Tumor‐Associated Enzyme NCEH1 with a Covalent PET Probe

Herein, we report the development of an ¹⁸F‐labeled, activity‐based small‐molecule probe targeting the cancer‐associated serine hydrolase NCEH1. We undertook a focused medicinal chemistry campaign to simultaneously preserve potent and specific NCEH1 labeling in live cells and animals, while permitting facile ¹⁸F radionuclide incorporation required for PET imaging. The resulting molecule, [¹⁸F]JW199, labels active NCEH1 in live cells at nanomolar concentrations and greater than 1000‐fold selectivity relative to other serine hydrolases. [¹⁸F]JW199 displays rapid, NCEH1‐dependent accumulation in mouse tissues. Finally, we demonstrate that [¹⁸F]JW199 labels aggressive cancer tumor cells in vivo, which uncovered localized NCEH1 activity at the leading edge of triple‐negative breast cancer tumors, suggesting roles for NCEH1 in tumor aggressiveness and metastasis.     

Evidence for a second,local contact condition for a planar electric double layer containing size and valency asymmetric ions

A generalised form of a local contact condition for the charge profile in a primitive model planar double layer [Bhuiyan, Outhwaite, and Henderson, Mol. Phys. 107, 343 (2009)] at low electrode charge is examined for completely asymmetric, binary electrolytes. The cation and anion sizes are taken to be different from each other with the valencies being 2⁺:1^? or 1⁺:2^?, while the electrode surface charge density is varied from being negative through zero to being positive. Monte Carlo simulation data obtained for such double layer systems at varying ionic radius ratios and electrolyte concentrations suggest the generalised contact relation to be valid at low charge on the electrode.     

Geometry and bond‐length alternation in nonlinear optical materials. II. Effects of donor strength in two push–pull molecules

The compounds N‐[2‐(4‐cyano‐5‐dicyanomethylene‐2,2‐dimethyl‐2,5‐dihydrofuran‐3‐yl)vinyl]‐N‐phenylacetamide, C₂₀H₁₆N₄O₂,(I), and 2‐{3‐cyano‐5,5‐dimethyl‐4‐[2‐(piperidin‐1‐yl)vinyl]‐2,5‐dihydrofuran‐2‐ylidene}malononitrile 0.376‐hydrate, C₁₇H₁₈N₄O·0.376H₂O, (II), are novel push–pull molecules. The significant bonding changes in the polyene chain compared with the parent molecule 2‐dicyanomethylene‐4,5,5‐trimethyl‐2,5‐dihyrofuran‐3‐carbonitrile are consistent with the relative electron‐donating properties of the acetanilido and piperidine groups. The packing of (I) utilizes one phenyl–cyano C—H...N and two phenyl–carbonyl C—H...O hydrogen bonds. Compound (II) crystallizes with a partial water molecule (0.376H₂O), consistent with cell packing that is dominated by attractive C—H...N(cyano) interactions. These compounds are precursors to novel nonlinear optical chromophores, studied to assess the impact of donor strength and the extent of conjugation on bond‐length alternation, crystal packing and aggregation.     

Development of an optical parametric generator with pulsed dye amplification for high-resolution laser spectroscopy

An injection-seeded optical parametric generator (OPG), coupled with three pulsed dye amplification (PDA) stages, was shown to produce tunable, narrow linewidth laser radiation. The OPG was composed of a pair of beta barium borate (β-BBO) crystals and pumped by the third harmonic (355 nm) output of a seeded Nd:YAG laser. The OPG was injection-seeded at the idler wavelength (824 nm) using an external cavity diode laser (ECDL) with a mode-hop-free tuning range of 20 GHz. Using the PDA stages, the OPG output signal (624 nm) was amplified to 19 mJ/pulse, while maintaining a spectral linewidth of approximately 160 MHz at full-width-half-maximum (FWHM) which was within a factor of 2 of the Fourier limit. A system of lenses and apertures was used to minimize amplified spontaneous emission (ASE) in the PDA stages. Using the OPG/PDA system, two-photon laser-induced fluorescence measurements of atomic oxygen were performed by sum-frequency-mixing the 624-nm beam with the third harmonic output of the seeded Nd:YAG laser to generate approximately 1 mJ/pulse of ultraviolet radiation near 226 nm. Voigt line shapes were found to be in good agreement with oxygen atom spectra in atmospheric-pressure, laminar, counter-flow flames; the magnitude of Doppler and collisional broadening was approximately the same. The measured O-atom concentration profile was found to compare well with that calculated using an opposed-flow flame code.     

A test of distribution function method in the case of liquid transition metals alloys

Atomic transport properties namely the shear viscosity and diffusion coefficients for Ni_xCo_1-x, Co_xFe_1-x and Ni_xFe_1-x liquid transition metal alloys are investigated systematically by employing statistical mechanical theory known as the distribution function method. As required we describe the interionic interaction by a local pseudopotential model that can take into account d-band effect adequately and, the pair correlation function is derived from the Percus-Yevick theory for hard spheres where the effective hard sphere diameter is determined by the LWCA thermodynamic perturbation theory. Results for shear viscosity agree well with the available experimental data for the whole range of concentration.     

AC Electrical Properties of Plasma Polymerized <Emphasis Type="Italic">o</Emphasis>-Methoxyaniline Thin Films

Alternate current (ac) electrical properties of the plasma polymerized o-methoxyaniline (PPOMA) thin films synthesized in the glow discharge plasma using a capacitively coupled reactor are studied. Measurement revealed that the ac electrical conductivity varies with frequency ω as ω ⁿ , where the exponent n is less than unity in the range 0.1 to 2.0 kHz, indicating the Debye type conduction mechanism in the PPOMA thin films, while above this frequency range the exponent is become greater than unity indicating non-Debye type conduction. At low frequencies the conduction is considered to be due to hopping of carriers between the localized states. The PPOMA thin films of thicknesses 100?250 nm possesses dielectric constant <10, which remains static in the range 0.1?10 kHz, and decreases at higher temperature due to the orientation polarization. The dielectric loss increases with the increase in frequency having a peak around or above 10 kHz for all the PPOMA films of different thicknesses. Cole-Cole plot between the real and imaginary dielectric constant exhibits single relaxation mechanism in the PPOMA thin films.     

Structures and properties of the compression-molded istactic-polypropylene/talc composites: Effect of cooling and rolling

Talc-loaded isotactic polypropylene (iPP) composites with various contents of talc were fabricated by compression molding, following slow- and fast-cooling processes, to obtain slow-cooled samples (SCS) and fast-cooled samples (FCS), respectively. Lamellar thickness of the α-crystal of iPP in the SCS is observed to be larger than that in the FCS by X-ray diffraction study. Rolled fast-cooled samples (RFCS) were also prepared at 25 °C in order to examine the crystal growth of iPP. An epitaxial growth mechanism of the α-crystal of iPP from the talc crystal is proposed. Surface of talc-loaded FCS appears with a smaller particle size than that of talc-loaded SCS and RFCS as observed by a scanning electron microscope. Young’s modulus and tangent modulus of FCS are found lower than those of SCS with the addition of talc up to 20 wt% and higher above this concentration, except microhardness which is higher in SCS at all contents of talc. From thermal studies, talc-loaded SCS and FCS are found to show higher melting temperature than the neat samples. Effect of cooling and rolling on the structures and properties of the fabricated composites are elaborately discussed.