The reaction kinetics of NiCl2 in silica-alumina gel matrix

Insitu isothermal reduction of NiCl₂ by dextrose in silica-alumina gel matrix has been carried out between 800 and 950 °C under nitrogen atmosphere. The predominant mechanism of reaction is found to be nucleation and growth. X-ray diffraction (XRD) analyses of reacted samples confirm the presence of metallic Ni, nickel aluminate and finely dispersed alumina in the reacted samples. The average particle size of nickel has been determined by transmission electron micrograph (14 nm) as well as XRD (17±2 nm).     

Fluorescence resonance energy transfer from tryptophan in human serum albumin to a bioactive indoloquinolizine system

The interaction between a bioactive molecule, 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ), with human serum albumin (HSA) has been studied using steady-state absorption and fluorescence techniques. A 1:1 complex formation has been established and the binding constant (K) and free energy change for the process have been reported. The AODIQ-HSA complex results in fluorescence resonance energy transfer (FRET) from the tryptophan moiety of HSA to the probe. The critical energy-transfer distance (R ₀) for FRET and the Stern-Volmer constant (K _sv) for the fluorescence quenching of the donor in the presence of the acceptor have been determined. Importantly, K _SV has been shown to be equal to the binding constant itself, implying that the fluorescence quenching arises only from the FRET process. The study suggests that the donor and the acceptor are bound to the same protein at different locations but within the quenching distance.     

Relativistic Ornstein–Uhlenbeck Process

We wish to shed some light on the problem of thermodynamic irreversibility in the relativistic framework. Therefore, we propose a relativistic stochastic process based on a generalization of the usual Ornstein–Uhlenbeck process: we introduce a relativistic version of the Langevin equation with a damping term which has the correct Galilean limit. We then deduce relativistic Kramers and Fokker–Planck equations and a fluctuation-dissipation theorem is derived from them. Finally, numerical simulations are used to check the equilibrium distribution in momentum space and to investigate diffusion in physical space.     

Reaction of 2-(arylazo)pyridine complexes of type [OsX2L2] (X = Cl or Br) with heterocyclic bases (B): spectra and electrochemistry of [OsX(B)L2]ClO4·H2O

Summary The synthesis and characterization of a series of complexes of the type [OsX(B)L₂] ⁺ (X = Cl or Br, B = pyridine (py) and pyrazine (pyz), L = 2-(phenylazo)pyridine (L¹) or 2-(m-tolylazo)pyridine (L²)) is described. The cations have been isolated as crystalline perchlorate monohydrates after purification by column chromatography. The diamagnetic compounds display several spin-allowed and spin-forbidden m.l.c.t. transitions in the visible region. The metal-centred oxidations and ligand-based reductions of the complexes are studied electrochemically in MeCN. Two consecutive one-electron oxidations corresponding to Os^III/Os^II and Os^IV/Os^III couples occur at ca. 1.3 and ca. 2.3 V versus s.c.e. respectively. Four successive azo-reductions are observable in the potential range -0.4 to -2.4V.     

An investigation into flow mode transition and pressure fluctuations for fluidized dense-phase pneumatic conveying of fine powders

This paper presents the results of an ongoing investigation into the fluctuations of pressure signals due to solids-gas flows for dense-phase pneumatic conveying of fine powders.Pressure signals were obtained from pressure transducers installed along different locations of a pipeline for the fluidized dense-phase pneumatic conveying of fly ash(median particle diameter 30μm;particle density 2300kg/m~3;loosepoured bulk density 700kg/m~3) and white powder(median particle diameter 55 u.m;particle density1600kg/m~3;loose-poured bulk density 620kg/m~3) from dilute to fluidized dense-phase.Standard deviation and Shannon entropy were employed to investigate the pressure signal fluctuations.It was found that there is an increase in the values of Shannon entropy and standard deviation for both of the products along the flow direction through the straight pipe sections.However,both the Shannon entropy and standard deviation values tend to decrease after the flow through bend(s).This result could be attributed to the deceleration of particles while flowing through the bends,resulting in dampened particle fluctuation and turbulence.Lower values of Shannon entropy in the early parts of the pipeline could be due to the non-suspension nature of flow(dense-phase),i.e.,there is a higher probability that the particles are concentrated toward the bottom of pipe,compared with dilute-phase or suspension flow(high velocity),where the particles could be expected to be distributed homogenously throughout the pipe bore(as the flow is in suspension).Changes in straight-pipe pneumatic conveying characteristics along the flow direction also indicate a change in the flow regime along the flow.     

Conversion of nuclear to 2-flavour quark matter in rotating compact stars: A general relativistic perspective

The conversion of neutron star to strange star is argued to be a two step process. The first process involves the deconfinement of nuclear to two-flavour quark matter. The GR results shows that the propagating front breaks up into fragments which propagate with different velocities along different directions. The time taken for this conversion to happen is of the order of few ms. This calculation indicates the inadequacy of non-relativistic (NR) or even Special Relativistic (SR) treatments for these cases.     

Isolation of a Diylide‐Stabilized Stannylene and Germylene: Enhanced Donor Strength through Coplanar Lone Pair Alignment

The preparation of the first stable diylide‐substituted stannylene and germylene ( Y₂E, with E=Ge, Sn and Y=[PPh₃‐C‐SO₂Tol]^?) is reported. The synthesis is easily accomplished in one step from the sulfonyl‐substituted metalated ylide YNa and the corresponding ECl₂ precursors. Y₂Ge and Y₂Sn exhibit unusual structures in the solid state and in solution, in which the three adjacent lone pairs in the C‐E‐C linkage are arranged coplanar to each other. As shown by DFT studies, this bonding situation is preferred over the typical π‐donation from the ligands into the empty p‐orbital at the metal due to the strong anion‐stabilizing ability of the sulfonyl groups in the ylide backbone and their additional coordination to the metal. The alignment of the three lone pairs leads to a remarkable boost of the HOMO energy and thus of the donor strengths of the tetrylenes. Hence, Y₂Ge and Y₂Sn become stronger donors than their diamino or diaryl congeners and comparable to cyclic alkyl(amino)carbenes. First reactivity studies confirm the high reactivity of Y₂Ge and Y₂Sn , which for example undergo an intramolecular C?H activation reaction via metal–ligand cooperation.     

Ultrafast Raman loss spectroscopy

This paper deals with a new form of nonlinear Raman spectroscopy called ‘ultrafast Raman loss spectroscopy (URLS)’. URLS is analogous to stimulated Raman spectroscopy (SRS) but is much more sensitive than SRS. The signals are background (noise) free unlike in coherent anti‐Stokes Raman spectroscopy (CARS) and it provides natural fluorescence rejection, which is a major problem in Raman spectroscopy. In addition, being a self‐phase matching process, the URLS experiment is much easier than CARS, which requires specific phase matching of the laser pulses. URLS is expected to be alternative if not competitive to CARS microscopy, which has become a popular technique in applications to materials, biology and medicine. Copyright © 2009 John Wiley & Sons, Ltd.     

The vibrational assignment of phenanthridine molecule based on normal coordinate analysis and DFT

A complete vibrational assignment of phenanthridine C13NH9 has been presented. The infrared (IR) and the Raman spectra of the molecule are analyzed with the help of theoretical prediction of the normal vibrational wavenumbers estimated from normal coordinate analysis (NCA) and density functional theory (DFT) calculations. A general valence force field (GVFF) including 31 parameters (13 diagonal and 18 off‐diagonal) reproduces satisfactorily the in‐plane vibrational signatures of the aforesaid molecule and as well as those for the other related hydrocarbons [phenanthrene and benzo(c)cinnoline]. The bivariate and multivariate data analysis reveals that calculated wavenumbers using GVFF are more accurate than the DFT result. However, DFT yields the relative Raman intensities, which are in good agreement with the experimental ones. The decomposition of the normal mode frequencies into those related to different internal coordinates is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Strong pionic intermittency in ‘cold’ events in12C-AgBr interactions at 4.5 A GeV

In this paper intermittent behaviour of the pions from ‘cold’ and ‘hot’ classes of events from¹²C-AgBr interactions at 4.5 A GeV has been studied, separately. The results reveal strong intermittent pattern in case of ‘cold’ class of events.