Integrated injection seeded terahertz source and amplifier for time-domain spectroscopy

We used a terahertz (THz) quantum cascade laser (QCL) as an integrated injection seeded source and amplifier for THz time-domain spectroscopy. A THz input pulse is generated inside a QCL by illuminating the laser facet with a near-IR pulse from a femtosecond laser and amplified using gain switching. The THz output from the QCL is found to saturate upon increasing the amplitude of the THz input power, which indicates that the QCL is operating in an injection seeded regime.     

Contribution of slow clusters to the bulk elasticity near the colloidal glass transition

We use confocal microscopy to visualize individual particles near the colloidal glass transition. We identify the most slowly-relaxing particles and show that they form spatially correlated clusters that percolate across the sample. In supercooled fluids, the largest cluster spans the system on short time scales but breaks up on longer time scales. In contrast, in glasses, a percolating cluster exists on all accessible time scales. Using molecular dynamics simulation, we show that these clusters make the dominant contribution to the bulk elasticity of the sample.     

The motive of the moduli stack of <Emphasis Type="Italic">G</Emphasis>-bundles over the universal curve

We define relative motives in the sense of André. After associating a complex in the derived category of motives to an algebraic stack we study this complex in the case of the moduli of G-bundles varying over the moduli of curves.     

Electrochemical and spectral characterization of blue copper protein models

Blue copper proteins play a central role in various enzymatic anabolic/catabolic pathways in living cells by virtue of the integrated metal ions. These ions may exist in variable oxidation states, with suitable reduction potentials and fast electron-transfer rates which in turn is a manifestation of their unusual geometry and co-ordination. We report the electrochemical and spectral characterization of three novel complexes of copper (II) with N₂S type tridentate chelating agent 2,2′-dithiodianiline (dta), having structural similarities to the active site of Type I copper proteins. High positive redox potentials in the range of 0.5–0.6 V vs Ag/AgCl electrode of the complexes and the absorption maxima at ～550 nm, with high extinction coefficients, correspond well with typical blue copper proteins. The IR and EPR studies support the assigned pseudo tetrahedral structures to the complexes. The diffusion coefficient and rate constant for heterogeneous charge transfer for Cu²⁺/Cu⁺ coordinated in a potentially bio-mimetic Type I site is reported.     

Oblique wave scattering by a semi-infinite rigid dock in the presence of bottom undulations

The problem of oblique wave scattering by a semi-infinite rigid dock in the presence of varying bottom topography is investigated here using linear water wave theory. Employing a simplified perturbation analysis together with appropriate use of Green’s integral theorem, the reflection coefficient up to first order is obtained in terms of an integral involving the shape function representing the bottom topography. The zero-order reflection coefficient is obtained by using the residue calculus method of complex variable. The bottom undulations are described by sinusoidal and an exponentially decaying profile. The first order correction to the reflection coefficient is depicted graphically in a number of figures for the two shape functions characterizing the bottom undulations and appropriate conclusions are drawn.     

Solid + liquid phase diagrams,NMR and colorimetric measurements of mixtures

Solid+liquid equilibrium, NMR and colorimetric measurements have been made for the mixtures of o-phenylenediamine+phenol, p-phenylenediamine+hydroquinone, m-phenylenediamine+phenol, m-phenylenediamine+hydroquinone, p-phenylenediamine+phenol, and p-phenylenediamine+hydroquinone. The types and melting temperatures of the complexes formed in these mixtures were ascertained from phase diagrams. The nature of the complexes was ascertained from colorimetric and NMR data.     

Stochastic analysis of transit systems

This paper presents two mathematical models representing on surface transit systems with general failure, towing and repair time distributions. The stochastic analysis is performed with the aid of the regeneration point technique. Laplace transforms of the state probabilities are obtained. A number of general formulas are developed for the transit system steady-state availability when one of the system transition rates is described by the Erlangian probability density function. Various plots of transit system steady-state availability are shown.     

Upper bounds for the essential dimension of the moduli stack of SL n -bundles over a curve

We find upper bounds for the essential dimension of various moduli stacks of SL _n -bundles over a curve. When n is a prime power, our calculation computes the essential dimension of the stack of stable bundles exactly and the essential dimension is not equal to the dimension in this case.     

Surface tensions and surface heats of mixing of mixtures of 1,2-dibromoethane with cyclohexane,benzene, toluene, o-xylene, m-xylene,and p-xylene at 298.15, 303.15, And 308.15 K

Surface tensions of mixtures of 1,2-dibromoethane+cyclohexane, benzene, +toluene, +o-xylene, +m-xylene, and +p-xylene have been measured as a function of composition at 298.15, 303.15 and 308.15 K. Interchange energies and surface heats of mixing in these mixtures were computed.     

Application of the sum peak method to determine electric field gradient in different environments of133Cs nucleus

The sum peak method based on the phenomenon of perturbed angular correlation has been applied to study the nuclear quadrupole interaction frequencies at¹³³Cs which is followed by electron-capture decay of¹³³Ba. These values are used to determine the z-component, which is the largest one of the electric field gradient. The electric field gradient /EFG/ is found to vary with different compounds of barium. The method is found to be useful in describing the chemical influences on the attenuation of angular correlations and hence in the study of EFG.