Difference of composition operators from the space of Cauchy integral transforms to Bloch-type spaces

In this paper, we characterize boundedness and compactness of difference of composition operators from the space of Cauchy integral transforms to Bloch-type spaces. Our characterizations are free from pseudo-hyperbolic metric, which is a common feature of all the characterizations of difference of composition operators acting between different spaces of holomorphic functions. Exact value of operator norm of difference of composition operators acting between these spaces is also computed.     

Effects of CO<Subscript>2</Subscript> infiltration on mobility and speciation of uranium at mineral–water interface

Laboratory batch experiment of CO₂ infiltration under closed conditions was conducted for a period of 30 days on mineral (uranium ore)–water system to understand, (a) how increased CO₂ concentration affects the mobility and speciation of uranium (U); (b) change in water chemistry due to CO₂ infiltration; and (c) identify geochemical signatures for identification CO₂ infiltration. After exposure to CO₂, water pH declines rapidly and again rebound and achieved equilibrium till end of the experiment. Speciation of U at mineral–water interface change from (UO₂)₂CO₃(OH) ₃ ^? to carbonato (UO₂CO₃), fluoride (UO₂F⁺) and sulfato (UO₂SO₄) complexes. pH and HCO₃ ^? were identified as best geochemical indicators for CO₂ infiltration.     

Modeling of 137Cs migration in cores of marine sediments of Mumbai Harbor Bay

The vertical concentration profile of ¹³⁷Cs in cores of marine sediment of Mumbai Harbor Bay has been studied by the compartment and the diffusion-convection models. Based on the measured concentrations of ¹³⁷Cs in the sediment layers, the various transport parameters such as sedimentation rate, residence half- time, effective migration velocity, diffusion coefficient and the convective velocities were determined. The sedimentation rate was determined to be 1.61, 1.03 0.69 and 1.25 cm year^?1 from the slope of lines obtained from the depth profile of ¹³⁷Cs in cores using a least-square fitting method at site 1, 2, 3 and 4 respectively. The mean residence half-times, ranging from 11 to 35 years were observed to be the highest at the upper layers (up to 8 cm) of all sites and decreased with sediment depth. Subsequently, the ranges of mean value of effective vertical migration velocity in the same layers were between 0.15 and 0.46 cm year^?1. As expected, the vertical migration in the upper sediment layers was very slow and thereafter increased slowly in the succeeding layers (12 cm onwards) of all sites with a mean ranging from 1.11 to 4.13 cm year^?1. The obtained migration velocities were quite higher than those reported in literatures for global fallout. The convective velocity and diffusion coefficient at each site were assumed to be constant in the whole depth and calculated under the assumption of steady state. Using a depth-zoned bioturbational mixing model, the estimated biological diffusion coefficients ranged from 7 × 10^?7 to 3.8 × 10^?6 cm² s^?1 which were within the literature values reported for shallow coastal environments and deep sea.     

Comprehensive studies on dielectric properties of p-methoxy benzylidene p-decyl aniline with function of temperature and frequency in planar geometry: A potential nematic liquid crystal for display devices

The dielectric properties of the nematic mesophase, p-methoxy benzylidene p-decyl aniline(MBDA), measured in planar geometry with a function of frequency and temperature are investigated in detail. The complex dielectric permittivity(ε' and ε') is also studied at a bias voltage of 10 V for planar aligned sample cell of nematic mesophase. The dielectric permittivity with bias voltage attains a higher( 2 times) value than that without bias voltage at a temperature of 56℃,which is due to the fact that the linking group of nematic molecules is internally interacted with an applied bias voltage.This is supported by observing an enhanced dielectric permittivity of nematic liquid crystal(LC) in the presence of bias voltage, which can be fully explained as the increasing of the corresponding dipole moment. The dielectric relaxation behaviors of nematic LC are also demonstrated for planar aligned sample cell. The remarkable results are observed that the relaxation frequency shifts into low frequency region with the increase of the bias voltage applied to the planar aligned sample cells. The dielectric relaxation spectra are fitted by Cole–Cole nonlinear curve fitting for nematic mesophase in order to determine the dielectric strength.     

Cr-free Co-Cu/SBA-15 catalysts for hydrogenation of biomass-derivedα-,β-unsaturated aldehyde to alcohol

Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of bio-mass-derived α-, β-unsaturated aldehyde (furfural) to value-added chemical furfuryl alcohol (FOL). Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings (2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray dif-fraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, ener-gy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemi-sorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the cata-lyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.     

Optimal stability envelope of the damped hauger system

Summary By using the Frobenius' method, the authors obtain the virtually exact instability boundary of the externally damped viscoelastic Hauger system. The interaction between the two types of damping, yields results paradoxical to those obtained with each type of damping considered separately. An optimal stability envelope, which for a prescribed value of internal damping and any external damping gives the highest attainable critical load, is obtained. The addition of external damping for a prescribed internal damping, raises the critical load at best to the above optimal value; further addition of external damping diminishes the critical load. The Ziegler's jump or pseudo-destabilization due to infinitesimal internal damping, is shown to vanish with the introduction of external damping. For large external damping, the Ziegler's jump approaches a negative asymptotic value. These paradoxical results provide a deeper insight into the complex interaction between the internal and external damping in polygenic systems.

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Sommario Usando il metodo di Frobenius gli autori ottengono il contorno di instabilità virtualemnte esatto del sistema viscoelastico Hauger smorzato esternamente. La interazione fra i due tipi di smorzamento porta a risultati paradossali rispetto a quelli ottenuti con ogni tipo di smorzamento considerato separatamente. Si ottiene un inviluppo ottimale di stabilità che per dati valori degli smorzamenti interni ed esterni dà il massimo carico critico ottenibile. L'aggiunta di smorzamento esterno per un prescritto smorzamento interno aumenta il carico critico al massimo fino al sopra citato valore ottimale; un aumento ulteriore di smorzamento esterno diminuisce il carico critico. Si dimostra che con l'introduzione di smorzamento esterno diminuisce la discontinuità di Ziegler e la pseudo-instabilità dovuta a smorzamento interno infinitesimo. Per forti smorzamenti esterni la discontinuità di Ziegler tende a un valore asintotico negativo. Questi risultati paradossali forniscono una più approfondita comprensione della complessa interazione fra smorzamento interno ed esterno nei sistemi poligenici.

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Direct numerical simulation of a turbulent axisymmetric jet with buoyancy induced acceleration

Direct numerical simulations of an axisymmetric jet with off-source volumetric heat addition are presented in this paper. The system solved here involves a three-way coupling between velocity, concentration and temperature. The computations are performed on a spherical coordinate system, and application of a traction free boundary condition at the lateral edges allows physical entrainment into the computational domain. The Reynolds and Richardson numbers based on local scales employed in the simulations are 1000 and 12 respectively. A strong effect of heat addition on the jet is apparent. Heating causes acceleration of the jet, and an increased dilution due to an increase in entrainment. Further, the streamwise velocity profile is distorted, and the cross-stream velocity is inward for all radial locations for the heated jet. Interestingly, the maximum temperature is realized off-axis and a short distance upstream of the exit of the heat injection zone (HIZ). The temperature width is intermediate between the scalar and velocity widths in the HIZ. Normalized rms of the concentration and temperature increases in the HIZ, whereas that of streamwise, cross-stream and tangential velocities increases rapidly after decreasing. Both mass flux and entrainment are larger for the heated jet as compared to their unheated counterparts. The buoyancy flux increases monotonically in the HIZ, and subsequently remains constant.     

Styrene acrylonitrile (SAN) based polymeric waveguides

In the present study styrene acrylonitrile based polymeric waveguides have been optimized with the help of aging (variation of baking time keeping the temperature constant), annealing (variation of baking temperature keeping the time constant), concentration and thickness (physical). Propagation losses are lowest at an annealing temperature of 100°C and aging time of 8 h. The values of effective refractive index of the waveguides change inconsistently between 1.566 and 1.569 and between 1.5660 and 1.5667 for aging and annealing effect, respectively. However, by increasing the physical thickness of the film, the value of refractive index was decreased. By increasing the concentration of the solution, the refractive index of the waveguides was increased. The birefringence in the present observation is of the order of 10⁻⁴. Polarization selective properties were also observed in the present study for certain range of concentration.     

Synthesis and studies of some 4-substituted phenyl-4'-azopyridine-containing hydrogen-bonded supramolecular mesogens

Novel azopyridine-containing supramolecular liquid crystalline (LC) materials built via 1 : 1-heterointermolecular hydrogen bonding between some 4-substituted phenyl-4'-azopyridines and 4- n -alkyloxybenzoic acids are reported. These hydrogen-bonded LC complexes exhibit well defined nematic, smectic A and smectic C phases over wide ranges of temperature depending upon the number of carbon atoms present in the alkyl chains. The formation of pure LC materials on 1 : 1-complexation could be confirmed from the phase diagrams of the binary mixtures, which clearly indicated a melting maximum for the 50 mol % mixture as well as the presence of two eutectic points on either side of this mixture.