A new look into the acquisition properties of a second-orderdigital phase locked loop

With the help of real-time numerical simulation results, the acquisition properties of a second-order ZC₁-DPLL are investigated. Besides confirming the sensitivity of the system dynamics to the initial values of the state variables, it predicts qualitatively the maximum possible frequency acquisition range (FAR) of the system, and obtains the values of the maximum FAR for systems with different design parameters. The effect of jitter on the loop dynamics has also been considered     

A generalized approach to steady-state analysis of a current-sourceinverter with induction motor load including commutation overlap

A generalized state-space approach is presented for the steady-state commutation analysis of an autosequential commuted current-source inverter-fed induction motor drive covering all possible modes of operation using a digital computer. The analysis adopts the basic per-phase equivalent circuit for the induction motor model, includes the effect of DC link filter impedance and the variation of back EMF during the commutation interval, and extends the inverter model to cover the complex commutation overlap mode occurring during high frequency operation. A digital computer program is evolved, to identify automatically the relevant sets of equations applicable to a particular mode from a generalized set of equations and to solve them     

Explicit two-loop calculation of decoupling in unbroken gauge theories with fermions

Unbroken gauge theories containing light as well as heavy fermions are considered in the limit of the mass of the heavy fermions tending to infinity. The effective coupling constant of the decoupled low-energy theory thus obtained, has been calculated up to two-loop level using the light particle irreducible vertex function and the background field formalism. In addition, to simplify the computation, a background field gauge-fixing term has been used, because in such a gauge the effective coupling constant can be calculated from a two-point function only. Our analysis reveals that in the non-abelian theory, the simple algorithm proposed by Ovrut and Schnitzer for computing the effective coupling constant up to the two-loop level is valid only in the α = 0 or α = ?3 background field gauge. A general procedure correct for all values of α is described.     

An unusual cleavage of a side chain during catalytic hydrogenation of some octalones

Novel hydrogenolysis of a CC bond linking a benzyl side chain in some octalones is described.     

Warm electron coefficient in polar semiconductors in the presence of strong electron-electron collisions

An iterative calculation of the warm electron coefficient is presented considering polar mode scattering in a parabolic band. Electron-electron collisions are assumed strong enough to establish a Maxwellian distribution function. The results vary considerably from those of the displaced Maxwellian calculation which has been used earlier for the interpretation of experimental results.     

High pressure X-ray diffraction study on p-FeS2, m-FeS2 and MnS2 to 340 kbar: A possible high spin-low spin transition in MnS2

Pyrite p-FeS₂, marcasite m-FeS₂ and MnS₂2 have been investigated using the high-pressure X-ray diffraction technique to 340 kbar. MnS2 undergoes a pressure-induced phase transition at about 140 kbar from the pyrite to the marcasite type phase with a volume contraction of about 15%. The high-pressure marcasite type m-MnS₂ is found to belong to the B type of marcasite with an axial ratio $\text{c}\text{a}\text{= 0.76}$ and $\text{c}\text{b}\text{= 0.62.}$ p-FeS₂ and m-FeS₂ do not undergo any phase transition in the pressure range investigated. The high spin p-MnS₂ has been found to be much more compressible (B_o = 760 kbar, B′_o = 5.4) than the low spin p-FeS₂ (B_o = 2154 kbar, B′_o = 5.5) and m-FeS₂ (B₀ = 1465 kbar, B′_o = 4.9) while the high-pressure m-MnS₂ has comparable compressibility (B_o = 2138 kbar, B′₀ = 5.0) with those of low spin p-FeS₂ and m-FeS₂. The p-MnS₂-m-MnS₂ phase transition might be accompanied by a high spin-low spin transition of Mn²⁺.     

Temperature and pressure dependence of the crystal structure of InTe: A new high pressure phase of InTe

InTe has been investigated using high pressure x-ray diffraction technique to 340 kbar InTe undergoes a pressure induced phase transition from the tetragonal TISe-type (B37) to the NaCl-type (B1) phase We have discovered a further pressure induced phase transition from the NaCl-type to the CsCl type (B2) phase at about 150 kbar The crystal structure of the tetragonal TISe-type InTe has been reinvestigated with x-ray diffractometer data Temperature variation of the lattice constants of the tetragonal InTe has been obtained in the range 297 to 505 K.     

Pressure induced phase transition in MnTe2

Energy dispersive high-pressure powder X-ray experiments have been performed for MnTe₂ up to a pressure of 20 GPa. MnTe₂ undergoes a discontinuous transformation from the cubic pyrite type structure to the orthorhombic marcasite type structure at 7.0±0.5 GPa upon increasing pressure. The transformation is accompanied by a large reduction in the specific volume (ΔV/V=0.18) which probably reflects different magnetic properties of the two modifications of MnTe₂.     

Monitoring Membrane Protein Conformational Heterogeneity by Fluorescence Lifetime Distribution Analysis Using the Maximum Entropy Method

Due to the inherent difficulty in crystallizing membrane proteins, approaches based on fluorescence spectroscopy have proved useful in elucidating their conformational characteristics. The ion channel peptide gramicidin serves as an excellent prototype for monitoring membrane protein conformation and dynamics due to a number of reasons. We have analyzed conformational heterogeneity in membrane-bound gramicidin using fluorescence lifetime distribution analysis of tryptophan residues by the maximum entropy method (MEM). MEM represents a model-free and robust approach for analyzing fluorescence lifetime distribution. In this paper, we show for the first time, that fluorescence lifetime distribution analysis using MEM could be a convenient approach to monitor conformational heterogeneity in membrane-bound gramicidin in particular and membrane proteins in general. Lifetime distribution analysis by MEM therefore provides a novel window to monitor conformational transitions in membrane proteins.     

Study of electron donor-acceptor complexes of tri-n-octyl amine with [60]- and [70]fullerenes and some other electron acceptors by absorption spectrophotometric method

Electron donor-acceptor (EDA) complexes of tri-n-octylamine (TOA) with [60]- and [70]fullerenes and some other electron acceptors have been studied in chloroform medium by absorption spectrophotometric technique. Charge transfer (CT) absorption bands are observed in the visible region. Vertical ionization potential of TOA was determined utilizing CT transition energy. Oscillator strengths, transition dipole strengths and resonance energies for all the complexes have been calculated. [60]Fullerene/TOA and [70]fullerene/TOA complexes are found to decay slowly with time. Kinetics of these reactions have been studied and activation energies for such processes have been estimated. Ab initio calculations suggest that complexation of [70]fullerene with TOA is enthalpy favoured.