Degeneracy-averaged and polarized cross sections for rotational scattering in (Ar,LiH)

Close-coupling calculations at 500 cm^?1 for the system (Ar,LiH) are used to obtain scattering amplitudes and cross sections for the rotational transitionsj = 1 to j'= 0, 2, 3, 4, 5,j = 2 to j' = 3 and j = 3 to j'= 4. The degeneracy-averaged cross sections are in reasonable agreement with experiment for two different simple model potentials. Values for m-dependent cross sections with respect to two frames of reference are compared with various rules for Δm and with the previous results for (Ar,LiH).     

Thermodynamic properties of (a pentyl ester + an-alkane). XIV. The HmEand VmEfor (an ester + an-alkane)

This paper presents experimental data for the excess molar enthalpies H_m^Eand excess molar volumes V_m^Eat T =  298.15 K and atmospheric pressure for 21 binary mixtures consisting of one of three pentyl esters (ethanoate, propanoate, and pentanoate) and one of seven odd n -alkanes (from pentane to heptadecane). The results have shown the mixing of these mixtures to be endothermic, with H_m^Evarying uniformly with the n -alkane chain length. The variation of V_m^Ewas also found to be uniform, with contraction effects observed for the mixtures that contained low molecular-weight hydrocarbons, and increasing with the pentyl ester chain length. Different group-contribution theories were used to calculate the excess properties for (an ester  +  an n -alkane). Comparison of the calculated and experimental results revealed that, in most cases, the differences increased with the molecular weight of the components. However, the differences for the calculated values of the excess volumes using the model of Nitta et al. decreased with n -alkane chain length but increased with ester chain length, the mean differences for the excess volumes being larger than 20 per cent.     

Clinicopathological values of NBS1 and DNA damage response genes in epithelial ovarian cancers

Epithelial ovarian cancers (EOCs) are highly lethal gynecological malignancies with a high recurrence rate. Therefore, developing prognostic markers for recurrence after chemotherapy is crucial for the treatment of ovarian cancers. As ovarian cancers frequently respond to DNA-damaging agents, we assessed the clinicopathological significance of key double-strand DNA break (DSB) repair genes, including BRCA1, BRCA2, BARD1, ATM, RAD51 and NBS1 in EOC cell lines and paraffin-embedded tissue sections from 140 EOC patients treated with cytoreductive surgery, followed by platinum-based chemotherapy. These samples were analyzed for the clinicopathological impact of DSB genes by western blot analysis, immunohistochemistry and quantitative real-time PCR. Of the DSB repair genes, BRCA1, ATM and NBS1, which are involved in the homologous recombination-mediated repair pathway, were related to aggressive parameters in EOC. When survival analysis was performed, NBS1 expression exhibited an association with EOC recurrence. Specifically, increased NBS1 expression was found in 107 out of 140 cases (76.0%) and correlated with advanced stage (P=0.001), high grade (P=0.001) and serous histology (P=0.008). The median recurrence-free survival in patients with positive and negative expression of NBS1 was 30 and 78 months, respectively (P=0.0068). In multivariate analysis, NBS1 was an independent prognostic factor for the recurrence of EOC. Together, these results suggest that NBS1 is a marker of poor prognosis for the recurrence of EOC and is associated with aggressive clinicopathological parameters.     

Thermodynamics of proton dissociations from aqueous l-proline: apparent molar volumes and apparent molar heat capacities of the protonated cationic,zwitterionic, and deprotonated anionic forms at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

Apparent molar volumes V_φ and apparent molar heat capacities C_p,φ were determined for aqueous solutions of l-proline, l-proline with equimolal HCl, and l-proline with equimolal NaOH at the pressure p=0.35 MPa. Density measurements obtained with a vibrating-tube densimeter at temperatures (278.15⩽T/K⩽368.15) were used to calculate V_φ values, and heat capacity measurements obtained with a twin fixed-cell, differential-output, power-compensation, temperature-scanning calorimeter at temperatures (278.15⩽T/K⩽393.15) were used to calculate C_p,φ values. Speciation arising from equilibrium was accounted for using Young’s Rule, and semi-empirical equations describing (V_φ, m, T) and (C_p,φ, m, T) for each aqueous equilibrium species were fitted by regression to the experimental results. From these equations, the volume change Δ_rV_m and heat capacity change Δ_rC_p,m for the protonation and deprotonation reactions were calculated. Additionally, the Δ_rC_p,m expression was integrated symbolically to yield values of the reaction enthalpy change Δ_rH_m, reaction entropy change Δ_rS_m, and equilibrium molality reaction quotient Q for both reactions. The results provide a much-improved thermodynamic characterization of aqueous l-proline and of its protonation and deprotonation equilibria.     

Exponential gap relation and the rotational inelasticity of H2M systems

Previously published values of state-to-state integral inelastic cross sections for the H₂(J_i)—M (M  H, He, Li, Li⁺, H₂, CO₂) systems are fitted to the exponential gap relation for the rotational inelastic process to obtain the C value that reflects the magnitudes of relative cross sections. While the vibration of the rotor seems to have little influence, the C value is shown to decrease dramatically with increase in initial collision energy T_i, ΔC/ΔT_i being larger at lower T_i for all systems analysed, in accord with the prediction of the surprisal synthesis of Procaccia and Levine. For the only case of H₂(J_i)-Li⁺ for which results are available for several J_i, C decreases with increase in J_i or J_i(J_i + 1)). The C value predicted by Procaccia and Levine for H₂M systems falls within the range of C values calculated for the various collision partners. However, there is a noticeable change in C (albeit within a factor of two) with change in M, indicating that dynamical factors do play an important role in rotational inelastic processes.     

Second-order perturbation theory for the angular pair correlation function in molecular fluids

Second-order perturbation theory is used to calculate spherical harmonic coefficients of the angular pair correlation function g(rω₁ω₂) for a liquid in which the molecules interact with a pair potential that is the sum of Lennard-Jones and quadrupole-quadrupole parts. The theory is compared with both molecular dynamics results and with the predictions of the GMF ≡ LHNC, QHNC and first-order perturbation theories. Second-order perturbation theory gives excellent results for the harmonic coefficient g(224,r), but is poorer for g(222,r) and g(202,r).     

Ultrasonic speed in compressed liquid by a sing-around method

A new apparatus for the measurement of ultrasonic speed in compressed liquid was constructed. The reliability of this instrument was confirmed by measuring the speeds in pure benzene in the ranges from 283.15 to 323.15 K and pressures up to near freezing pressure, and by comparing the results with literature values. The isentropic compressibilities κ_S were also determined using the experimental speeds and densities, and the results κ_S(u) were compared with those observed directly elsewhere κ_S(d) and those calculated thermodynamically κ_S(c) from (p, V_m, T). At atmospheric pressure, the present results, while agreeing with κ_S(u) reported in the literature, show differences from κ_S(d) and κ_S(c), while those for higher pressures close on a simple curve with κ_S(c).     

The general solution of the coagulation equation for branched polymers

The coagulation equation with a bilinear kernel, K_ij = [(f − 2) i + 2][(f − 2) j + 2], and arbitrary initial conditions c_k (0), is solved both for finite f, and in the limit f → ∞. Analytic expressions are given for the size distribution before and after gelation and for the gelation times. The correspondence with a generalized version of Flory's probability argument is shown.     

On the characterization of BiMO2NO3 (M=Pb, Ca, Sr, Ba) materials related with the Sillén X1 structure

The compounds BiMO₂NO₃, with M=Pb, Ca, Sr, and Ba, were obtained as single-phase products from solid-state reactions in an atmosphere of nitrous gases. The oxide nitrates with Pb and Ca crystallize in the tetragonal space group I4/mmm with two formula units per unit cell; the oxide nitrates with Sr and Ba crystallize in the orthorhombic space group Cmmm with four formula units per unit cell. Lattice parameters at room temperature are a=397.199(4), c=1482.57(2) pm for M=Pb; a=396.337(5), c=1412.83(3) pm for M=Ca; a=1448.76(3), b=567.62(1), c=582.40(1) pm for M=Sr and a=1536.50(8), b=571.67(3), c=597.55(3) pm for M=Ba. The structures, which were refined by powder X-ray diffraction, consist of alternating [BiMO₂]⁺ and [NO₃]⁻ layers stacked along the direction of the long axis. IR and thermogravimetric data are also given. The various M²⁺ cations in BiMO₂NO₃ are compatible with each other; therefore and because of their layer-type structure, these compounds are interesting precursors for oxide materials, e.g., the HTSC compounds (Bi,Pb)₂Sr₂Ca_n−1Cu_nO_x.     

Biochemical study for the effect of henna (Lawsonia inermis) on Escherichia coli

Leaf samples of Lawsonia inermis (Li) were examined for their antimicrobial potential. Broth extracts in different concentrations were prepared and bioassayed in vitro for the growth of Escherichia coli. The growth of E. coli pathogen was inhibited to various degrees by increasing the concentration of the herbal powder. In addition to the observed alterations which were detected electrophoretically in the protein pattern, were activities of the amylase enzyme and glycoprotein fractions. The protein pattern has one common band of Rf 0.47 and two characteristic bands of Rf 0.36 and Rf 0.42 for E. coli sample. The quantitative mutation was observed in the bacteria with different concentrations of L. inermis compared with the control. Some types of proteins in E. coli completely disappeared upon being S.I affected. The amylase pattern showed one common band with Rf 0.037 and two characteristic bands with Rf 0.18 and Rf 0.37 for E. coli sample. The obvious quantitative mutation observed in bacteria with different concentrations of L. inermis compared with E. coli. The glycoprotein pattern recorded one common band at R₁ with Rf 0.94 for E. coli sample and bacteria inoculated with different concentrations of L. inermis. These results confirmed the antibacterial activity of henna leaves and supported the traditional use of the plant in therapy of bacterial infections and disturbances that occurred at the biochemical level. The broth extract of the L. inermis leaves showed obvious antibacterial activity against E. coli.     

Vibrational spectra and vibrational states of simple gas-phase hydrogen-bonded dimers

The article aims to outline the growth of evidence and ideas about infrared band broadening for simple, gaseous, moderately strong, hydrogen bonded dimers B…HA, to draw attention to areas in need of further development and to collect together experimental information available at the present time about vibrational states associated with such dimers. The band associated with the modified HA stretching mode, ν_s, is observed for several dimers not only to be broad, but to have sub-band structure, which is satisfactorily interpreted as arising from combination bands of ν_s with the low frequency stretch-mode ν_σ, giving a progression ν_s ± nν_σ as a result of strong anharmonic coupling. For weaker dimers with lower values of ν_σ the sub-band structure is less evident, and may appear only as shoulders, while for still weaker dimers, the sub-bands may be merged into a featureless broad band. A major factor contributing to the breadth of the individual sub-bands in the band structure is the presence of hot-bands, especially a long series based on successive excited states of the low-frequency bending mode ν_β. A link is indicated with the interpretation of band-broadening for moderately strong hydrogen-bonded complexes in the liquid state. The anharmonic coupling of ν_s and ν_σ is again a central feature but there is a new factor, namely the coupling of ν_σ through a fluctuating potential with the surroundings, which has the result that the ν_s mode rapidly loses phase coherence resulting in a broad structureless band.     

Energy dependence of rotational and vibrational distributions of N2(C) for the Ar*(3P0,2) + N2(X) excitation transfer reaction

The Ar* + N₂(X) → N₂(C, v′, N′) + Ar excitation transfer reaction has been investigated experimentally in two different atomic beam experiments. The inelastic cross sections Q_{v′ = 0}(E) and Q_{v′ = 1}(E) to the v′ vibrational level have been measured in the energy range 0.06 ⩽ E(eV) ⩽ 6, using a crossed beam machine. Both cross sections show a behaviour typical for a curve crossing mechanism, with maximum values Q₀ = 8.0 Ų and Q₁ = 1.2 Ų at E = 0.16 eV and E = 0.13 eV, respectively. The oscillatory behaviour of the ratio Q₁(E)/Q₀(E), as first observed by Cutshall and Muschlitz, is also present in our data. Within the model of Gislason et al. the results indicate a decreasing bond stretching with increasing energy. As an alternative we discuss the possibility that the oscillation is due to a different energy dependence of the cross sections for the Ar*(³P₀) and Ar*(³P₂) fine structure states in the mixed beam of metastable Ar*. The vibrational and rotational distributions have also been measured at E = 0.065 eV in a small scale atomic beam-scattering cell experiment, which can be considered as an intermediate between a bulk experiment and a crossed beam experiment. The relative vibrational populations are n_v′ = 100, 16.0, 3.03 and 0.31 for v′ = 0 through 3, with rotational “temperatures” of T_rot,v′ = 1960, 1010, 370 and 130 K. Pronounced deviations (“hump”) of the Boltzmann rotational distributions occur at N′ ≈ 27 for v′ = 0, 1 and 2, with a fractional population of 1, 3 and 11%. For v′ = 0 the “hump” is largely obscured by overlap with the v′ = 1 bandhead. These bimodal distributions are in qualitative agreement with the results of Nguyen and Sadeghi for v′ = 0. The results are discussed within the framework of a curve crossing mechanism with the Ar⁺-N⁻₂ diabatic potential as an intermediate. By assuming equal charges on both N atoms the Coulomb potential of the collinear orientation lies lower (0.45 eV at R = 2.5 Å) than the perpendicular orientation, with the consequence of different transfer probabilities for both orientations. Within a classical model or rotational excitation the final N′ values can be calculated for both orientations, resulting in much higher N′ values for the perpendicular orientation. This mechanism supplies a qualitative explanation for the observed bimodal rotational distributions.     

Relation of gas-transport parameters of amorphous glassy polymers to their free volume: Positron annihilation study

Correlations of transport parameters (diffusion coefficients D and permeabilities P of gases) and thermodynamic parameters (solubility coefficients S and parameters C′ _H of sorption isotherms) with the sizes of free-volume elements, v _h, as estimated via positron annihilation lifetime spectroscopy are analyzed for the first time on the basis of the data array obtained for glassy polymers. Correlations of logD and logP with 1/v _h that agree with the free-volume model under the condition of a weak change in the concentration of free-volume elements in different polymers are ascertained. Certain deviations from linear correlations with 1/v _h for polymers with high free volumes are interpreted as evidence that the connectivity (openness) of pores increases with the sizes of free-volume elements. For solubility coefficients and Langmuir parameters of sorption capacity C′ _H , good linear correlations with the value of v _h are demonstrated.     

Radiative lifetime of CO+ (X2∑+, ν) ions

The radiative relaxation of CO⁺(X²∑⁺, ν) ions produced by ionization of CO and of OCS with 70 eV electrons has been investigated using the monitor ion technique in a triple FT ICR spectrometer. Since the monitor reaction is exothermic for ν ≥ 1, the experimental lifetimes, 170 ms for CO⁺ from CO and 210 ms for CO⁺ from OCS, should correspond to the overall decay rate of ν ≥ 2 with a small contribution of ν = 1.These values being much larger than the theoretical lifetime of ν = 1 (128.5 ms), computer-simulated overall lifetimes for ν ≥ 1 and ν ≥ 2 have been determined using theoretical lifetimes calculated by Rosmus and Werner and a vibrational population deduced from photoelectron spectroscopy of CO with 40.8 eV photons (Gardner and Samson). The computer-simulated lifetimes, 250 ms for ν ≥ 1 and 125 ms for ν ≥ 2, are indeed about twice as large as the theoretical lifetimes for ν = 1 and ν = 2, respectively, indicating that the large experimental lifetimes may be accounted for by radiative cascade from the upper vibrational levels.     

Concentration dependence of critical exponents for gelation in gellan gum aqueous solutions upon cooling

The sol-gel transition in aqueous gellan gum solutions induced upon cooling was investigated by rheology measurements. The gelation temperature was determined from the crossover point of storage and loss moduli, i.e., G′ = G′′ (T_c) and from the Winter’s criterion (T_gel), respectively, which increased with gellan concentration. T_gel was higher than T_c and the difference became larger as the gellan concentration got higher. The relaxation critical exponent n was estimated with the Winter’s method and the self-similarity was observed from the critical gel. The scaling for the zero-shear viscosity η₀ before the gel point and the equilibrium modulus G_e after the gel point was established against the relative distance ε from the gel point over the gellan concentration C_g of 1.0-2.5 wt%, giving the critical exponents k and z. The critical exponent n calculated from k and z agrees well with n from the Winter’s criterion. However, no universal n was found for the gelation in aqueous gellan gum solutions, indicating that this gelation should be classified into the cross-linking category for the physical gelation. The critical exponent n decreased with increasing C_g for the gellan gum solution. The fractal dimension d_f calculated from n with the screened hydrodynamic interaction and the excluded volume effect suggested a denser structure in the critical gel with higher C_g.     

The vapour pressure behaviour and the association of N-methylethylamine,diethylamine and their N-deuterioanalogues in mixtures with n-hexane

The vapour pressure isotherms of mixtures of N-methylethylamine and N-methyl(N-²H)ethylamine with n-hexane have been measured between 273 and 323 K. The vapour pressure isotherms of mixtures of diethylamine and (N-²H)diethylamine with nhexane between 293 and 353 K have also been measured. In addition, the vapour pressures of the pure amines have been determined down to 228 or 243 K. As evidenced by the small values for the Wilson coefficients, the activity coefficients, the Gibbs free energies and the data derived from the theory of ideal associated solutions, the association of diethlamine is very weak; that of N-methylethylamine is not much larger. The observations on the vapour pressure isotope effect of the two amines and their N-deuterioanalogues are compatible with this interpretation. The normal effect is smaller for diethylamine, with ratios P_D/P_H of 0.972–0.997 between 243 and 323 K, than for N-methylethylamine with values of 0.965–0.991, and the partial pressure quotients calculated for mixtures of the two compounds with n-hexane show the transition from the normal to the inverse effect on low dilution. The data for the N-deuterioanalogues and their mixtures with n-hexane suggest a somewhat greater energy of the deuterium bonds.     

Excess molar volumes and dynamic viscosities for binary mixtures of toluene + n-alkanes (C5–C10) at T = 298.15 K – Comparison with Prigogine–Flory–Patterson theory

Densities ρ, dynamic viscosities η, for binary mixtures of toluene with some n-alkanes, namely, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane have been measured over the complete composition range. Excess molar volumes V^E, viscosity deviations Δη, and excess Gibbs free energy of activation ΔG^1E, were calculated there from and were correlated by Redlich–Kister type function in terms of mole fractions. For mixtures of toluene with n-pentane and n-hexane the V^E is negative and for the remaining systems is positive. The Δη values are negative for all the studied mixtures. The ΔG^1E values shows the positive values for the binary mixtures with n-decane, whereas the negative values have been observed for all the remaining binary mixtures. From the results, the excess thermal expansivities at constant pressure α^E, is also estimated. The Prigogine–Flory–Patterson (PFP) theory and its applicability in predicting V^E is tested. The results obtained for viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg and Nissan, Tamura and Kurata, Hind et al., Katti and Chaudhri, McAllister, Heric, Kendall, and Monroe. The experimental on the constituted binaries are analyzed to discus the nature and strength of intermolecular interactions in these mixtures.     

Chemical effect on L X-ray fluorescence cross-sections of Hg,Pb and Bi compounds

Chemical effect on the photon induced L X-ray fluorescence cross-sections (σ_Lα, σ_Lβ and σ_Lγ) for Hg, Pb and Bi compounds were investigated. The samples were excited by gamma rays with energy 59.5 keV from ²⁴¹Am radioisotope source. L X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. We observed chemical effect on the photon induced L X-ray fluorescence cross-sections (σ_Lα, σ_Lβ and σ_Lγ) for Hg, Pb and Bi compounds. Our values were compared with calculated theoretical values.     

Elastic behavior of non-Gaussian polymethylene chains

In this paper, elastic behaviors of non-Gaussian polymethylene (PM) chains with chain length N=100 are investigated by rotational isomeric state model. Here the tetrahedral lattice of PM chain and the non-local interaction of Sutherland potential are adopted. In the metropolis movement of PM chain, a four-bond movement model is used. The average energy and average Helmholtz free energy with various elongation ratios λ are calculated by Monte Carlo simulation method. The average energy increases with elongation ratio λ and the average Helmholtz free energy decreases with elongation ratio λ. The elastic force f and the energy contribution to elastic force f_u can be obtained from f=∂〈A〉/∂r and f=∂〈U〉/∂r. We find that the elastic force f increases with elongation ratio λ and the energy contribution f_u decreases with elongation ratio λ, and f_u is less than zero. The ratio f_u/f is close to −0.21 for λ?1.25, and −0.04 to −0.35 for λ>1.25 at T=364 K. In our calculation, the rubber elasticity may be discussed in terms of the chemical structure of polymer chains.     

Electrical conductivity and high resolution electron microscopy studies of WO3−x crystals with 0 ≤ x ≤ 0.28

WO_3?x crystals with 0 ≤ x ≤ 0.28 have been studied by means of HREM and electrical conductivity measurements. Semiconducting behavior with andE_a of the order 0.06 eV was observed for crystals which, according to the HREM study, contained {102}CS planes (x ? 0.03). Plots of conductivity vs1–T for WO₃ and WO_3?x containing disordered {102}CS planes are also presented. Metallic behavior was found for crystals with ordered {103}CS planes (x ? 0.11), for W₁₂O₃₄ (x = 0.167), and for W₁₈O₄₉ (x = 0.28).