Volume 57, Issue 1-2

We apply the methods recently developed for computation of type IIA disk instantons using mirror symmetry to a large class of D-branes wrapped over Lagrangian cycles of non-compact Calabi-Yau 3-folds. Along the way we clarify the notion of “flat coordinates” for the boundary theory. We also discover an integer IR ambiguity needed to define the quantum theory of D-branes wrapped over non-compact Lagrangian submanifolds. In the large N dual Chern-Simons theory, this ambiguity is mapped to the UV choice of the framing of the knot. In a type IIB dual description involving (p; q) 5-branes, disk instantons of type IIA get mapped to (p; q) string instantons. The M-theory lift of these results lead to computation of superpotential terms generated by M2 brane instantons wrapped over 3-cycles of certain manifolds of G2 holonomy

The method for simulating the second moment of the NMR absorption spectrum as a function of temperature is presented. The second moment is first calculated as a function of the number of jumps of rotating molecules or their parts (like methyl groups). This number of jumps is rescaled into the frequency of internal rotation and these frequencies are recalculated into equivalent temperatures. The relation between frequency of rotation, and temperature is established on the basis of the Arrhenius relation υ c = υ o exp (-E a /RT). The described method is then applied to the analysis of molecular motion in trimethylamine borane (CH 3 ) 3 NBH 3 . The proposed method is especially useful in the case of complex structures, where combined motions are possible, because the NMR second moment is much more sensitive to the geometry of motion than the magnetic relaxation times T 1 or T 1p usualy used in studies of the internal dynamics of solids.

Two radicals, formed frum niethylglyuinateliyilrocliliiriile, C 3 H 8 CINO 2 , wysudb un inadhuiuii with 7 rays, have been identified as CH 2 CŌOCH 3 and ĊŌOCH 3 .

In engineering and physical sciences, solitons and nonlinear evolution equations are of current interest. To the generalized reaction Duffing model, we report several families of exact solitonic solutions, including shock waves and bell-shaped waves. Some of the observable solitonic features are pictured out

The anisotropic g-factors g x , g y , and g z for Co 2+ in rutile crystal are studied from the secondorder perturbation formulas based on the cluster approach. In the studies, the contributions due to covalency effects, the configuration interaction and the rhombic crystal field are taken into account. The calculated values are close to the observed ones. The small discrepancy between calculation and experiment is discussed

A variety of molecular-graph-based structure-descriptors were proposed, in particular the Wiener index W. the largest graph eigenvalue λ 1 , the connectivity index X , the graph energy E and the Hosoya index Z, capable of measuring the branching of the carbon-atom skeleton of organic compounds, and therefore suitable for describing several of their physico-chemical properties. We now determine the structure of the chemical trees (= the graph representation of acyclic saturated hydrocarbons) that are extremal with respect to W , λ 1 , E, and Z. whereas the analogous problem for X was solved earlier. Among chemical trees with 5. 6, 7, and 3k + 2 vertices, k = 2,3,..., one and the same tree has maximum λ 1 and minimum W, E, Z. Among chemical trees with 3k and 3k +1 vertices, k = 3,4...., one tree has minimum 11 and maximum λ 1 and another minimum E and Z .

Two-dimensional exchange 35 Cl NQR spectroscopy has been applied for studies of the CCl3- group reorientation processes in chloral hydrate. The experimental results are interpreted on the basis of the 2D-exchange NQR theory, which takes into account the off-resonance irradiation. The pulse-optimisation procedure, which is required by this theory, enabled the detection of the 2D-exchangeNQRspectrum andwas applied to the quantitative study of the exchange processes in chloral hydrate. A temperature dependent study of the exchange rate revealed two different activation processes in the temperature ranges from 240 to 295 K and from 295 to 310 K, respectively

Investigations using surface acoustic waves provide information on the elastic properties of thin films. Residual stresses change the phase velocity of the surface waves. We have calculated the phase velocity and dispersion of surface waves in thin silver films with a strong [111]-fibre texture. A non-linear description of surface waves propagating along the [110]-direction of the substrate has been developed on the basis of an acoustoelastic theory, taking into account residual stresses. The relative change Δc/c of the velocity v was found to be linear for large excitation frequencies. The dispersion curves were measured using a photoacoustic method. For sputtered polycrystalline thin silver films we found good agreement between the experimental and calculated dispersion curves for frequencies up to 225 MHz

Raman scattering has been employed to study the temperature and polarization dependence of the vibrational modes for the glass-forming halide salt mixtures xZnCl 2 -(1-x)AlCl 3 , with x = 0.8 and 0.6. The analysis has shown that the vibrational modes of the mixtures arise from a contribution of the vibrational modes of the pure components salts. Emphasis has also been given to the low-frequency modes (3 - 80 cm -1 ), and particular points related to the glass transition phenomenology are discussed in view of the experimental findings.

Some types of anodes thai could replace die usual carbon anodes in aluminium production by die Hall-Keroult process are based on SnO 2 . The presenr Investigation deals nidi SnO 2 -Sb 2 O 3 -CuO ceramics having an SnO 2 . conrent of ≥ 96%), Sb 2 O 3 , and CuO being dopants The ceramic pellets, thermally treated at 1400 °C for 4 hours, were analysed by X-ray diffraction and IR. spectroscopy. The structural analysis of the samples evidenced an SnO 2(88) type solid solution. All samples were electronically conductive (small negative values of the Seebeck coefficients), having an sanation energy ranging within 0.02 - 0.3 eV. The anodic polarisation curves obtained with those anodes in an electrolyte of 88 % Na 3 AlF 6 , 7% Al 2 O 3 , and 5% CaF 2 were studied- The results were correlated with the microstrucrure of die invesagated samples.

The rotational spectra of discharge produced 13 C isotopomers of fluorodiacetylene were recorded with high sensitivity to improve the centrifugal distortion analysis. Stimulated by the sensitivity attained by the spectrometer the investigation was extended to detect the hitherto unknown fluorotriacetylene. The spectrum of a linear molecule was found, which with high probability belongs to fluorotriacetylene

Heat capacities of solid SmCl 3 and TmCl 3 were measured by differential scanning calorimetry in the ternperature range from 300 K up to the respective melting temperatures. The heat capacity of liquid SmCl 3 was also investigated. These results were compared with literature data and fitted by a polynomial temperature dependence. The temperature coefficients were given. Additionally, the enthalpy of fusion of SmCl 3 was measured. Furthermore, by combination of these results with the literature data on the entropy at 298.15 K, S 0 m (LnCl 3 , s, 298.15 K) and the standard molar enthalpy of formation of Δ form H 0 m (LnCl 3 ,s, 298.15 K), the meruiodynaniic functions were calculated up to T = 1300 K.

The influence of the second coordination sphere on die electroreduction of hafnium complexes to hafnium metal and the redox reaction Eu(III)+e - ⇔ Eu(II) in alkali halide melts was studied. It is shown that die large caesium cations in the melt reduce the transfer and the diffusion coefficients as well as the heterogeneous rate constants for charge transfer of harnitcn complexes. The standard rare constants for the europium redox reaction increase when going from NaCl-KCl to CsCl. The different influence of die second coordination sphere on the electrode reactions is explained by different limitation stages for electron transfer

The photoswitching of the energy gap width of the isomeric forms of photoresponsive polymers with homomiclear photochrome diaryletheue elementary units is investigated theoretically, taking into account the correlation correction. It is shown that a real switching of electrical conductivity (insulator ⇔ semiconductor or conductor) can not be realized with polymers with alternant homomiclear π -electron systems within the elementary unit. A change and tuning-in of the light absorption is possible in most cases.

The fluorescence of ACRYLODAN (6-acryloyl-2-dimethylamino-naphtalene) consists of two bands in liquid polar solvents like 1,2-dichloroethane, N,N-dimethylformamide, or acetonitrile. The intensity ratio of long emission (LE) and short emission (SE) bands, LE/SE, depends on the excitation wavelength. For λ exe = 420 nm only LE band appears. The observed two fluorescence bands of ACRYLODAN in polar solvents containing trace amounts of water originate from two different components: LE of ACRYLODAN and SE of the product resulting from hydrolysis back to 2-dimethylaminonaphtalenic acid.

The phase diagrams of Er-Sb and Er-Bi have been obtained. Erbium forms three compounds with antimony as well as bismuth. The antimonides and bismuthides Er 5 Sb 3 (1640°C), Er 5 Bi 3 (1427°C), ErSb 2 (650°C) and ErBi 2 (595°C) are formed by peritectic reactions. ErSb (2040°C) and ErBi (1860°C) melt congruently

The phase diagrams of Tb-Bi has been obtained. A peritec reaction develops as a result of bismuth addition, the transformation temperature of terbium being lowered by 18°C. Eutec reactions occur at 17 at.%Bi and 1090°C, and at more than 99 at.%Bi and 269°C. There are four compounds in the system: Tb 5 Bi 3 , Tb 4 Bi 3 , TbBi, and TbBi 2 , resulting from peritectic reactions at 1480, 1570, 1770 and 720°C. While TbBi melts congruently at 1920°C. Tb 5 Bi 3 and TbBi were observed to exhibit transformation

Smectic and comprehensive investigations on the phase transition studies of p-n-alkoxybenzylidene-p-n-alkyl anilines (nO.m’s) reveal the occurrence of direct smectic-F transition from isotropic liquid in higher homologues. We report the influence of terminal alkyl- and/or alkoxy-chain lengths on the manifestation and stabilization of this unique phase variant