Impact Parameter-Dependent Parton Distributions for a Relativistic Composite System

We investigate the impact parameter-dependent parton distributions for a relativistic composite system in light-front framework. We express them in terms of overlaps of light-cone wave functions for a self-consistent two-body spin- state, namely an electron dressed with a photon in QED. The pdf’s are distorted in the transverse space for transverse polarization of the state at one-loop level.     

Microwave Spectrum and Conformation in 2-Fluorophenylisothiocyanate

The microwave rotational spectra of 2-fluorophenylisothiocyanate have been investigated in the frequency region of 26.0-38.0 GHz. Analysis of a-type R-branch transitions confirmed the existence of two conformers: cis and trans. Rotational and centrifugal distortion constants for both conformers have been derived. The observed inertial defect values demonstrate their planarity. From the relative intensity ratio the cis form was shown to be more stable than the trans form by about 208 cm(-1). Finally, molecular geometries for both conformers have been proposed. Copyright 2000 Academic Press.     

Study on typical behavior of transient nature (I-t) and hysterisis nature of I–V characteristics of dye doped solid state thin film photoelectrochemical cell

In this present investigation, we describe the steady state current voltage (I–V) characteristic of Crystal violet dye dispersed solid state photoelectrochemical cell (PEC). Typical behavior of dark current-voltage characteristic by increasing and decreasing external bias voltage has a similar form like hysterisis in nature. Although we have already observed this hysterisis nature in case of both forward and reverse bias condition, yet it is clear that the reverse hysterisis curve is more prominent than forward hysterisis. In this paper, we are getting double values of current (I) for a single value voltage, which is also helpful to understand the charge transport process through disordered materials. As the bias increases, the distribution of traps depth, which is exponential in nature, changes toward order state (resulting increase in disordered parameter α) This means that as α increases, it tends to reach the most order state of material. When external bias voltage is at 3.5 V, the value of disorder parameter becomes 1, and when bias voltage is beyond 3.5 V, the diffusion comes enhanced in nature.     

Chemical reactions in the atomization of molybdenum in graphite furnace atomic absorption spectrometry

Summary Chemical reactions in the atomization of molybdenum in graphite furnace atomic absorption spectrometry have been studied using graphite platforms for atomization along with X-ray diffraction analysis. When Mo [as an aqueous solution of (NH₄)₂MoO₄] is heated in a graphite furnace, three molybdenum oxides: [MoO_2(s), MoO_3(s) and Mo₄O_11(s)], are formed at relatively low temperatures (<1,500 K). When Mo is atomized from a pyrolytic graphite surface, the charring curve of Mo shows a dip in absorbance in the temperature range 1,200–1,800 K. Hence, a charring temperature <1,200 K should be used for quantitative determination of Mo when a pyrolytically coated tube or a platform made of pyrolytic graphite is used. Mo_(s), MoC_(s) and Mo₂C_(s) have been found on both the pyrolytic and the regular graphite surface after the charring step is completed. Formation of Mo_(g) by direct sublimation of Mo_(s) and by dissociation of MoC_(g) are all thermodynamically favourable reactions at the temperature considered.

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Chemische Reaktionen bei der Atomisierung von Molybdän in der Graphitofen-AAS

Zusammenfassung Die chemischen Reaktionen bei der Atomisierung von Molybdän wurden mit Hilfe von GraphitPlattformen zusammen mit der Röntgen-Diffraktionsanalyse untersucht. Bei der Erhitzung von Molybdän [als wäßrige (NH₄)₂MoO₄-Lösung] im Graphitofen werden drei Molybdänoxide (MoO_2(s), MoO_3(s) und Mo₄O_11(s)) bei relativ niedrigen Temperaturen (<1 500 K) gebildet. Wenn Molybdän von einer pyrolytischen Graphitoberfiäche atomisiert wird, zeigt die Veraschungskurve eine Absenkung der Extinktion im Bereich von 1200 bis 1800 K. Deshalb sollte bei Verwendung eines mit pyrolytischem Graphit überzogenen Rohres oder einer entsprechenden Plattform für quantitative Molybdänbestimmungen eine Veraschungstemperatur von <1 200 K benutzt werden. Nach der Veraschungsstufe wurden sowohl auf der pyrolytischen als auch auf der normalen Graphitoberfläche Mo_(s), MoC_(s) und Mo₂C_(s) gefunden. Bildung von Mo_(g) durch direkte Sublimation von Mo_(s) und durch Dissoziation von MoC_(g) sind thermodynamisch günstige Reaktionen bei der betreffenden Temperatur.

     

SENSITIZER-INDUCED CONFORMATIONAL CHANGES IN LENS CRYSTALLIN—II. PHOTODYNAMIC ACTION OF RIBOFLAVIN ON BOVINE α-CRYSTALLIN

Abstract— Photolysis of α-crystallin in the presence of riboflavin under both aerobic and anaerobic conditions causes a rapid decrease in Trp emission; photooxidation most likely occurs via non-covalent complex formation between the sensitizer molecule and the substrate. However, the change in the tertiary structure of the protein, as manifested in the near-UV CD, is very different between aerobic and anaerobic photolysis. Riboflavin-sensitized reaction under aerobic condition causes a major change in the microenvironments of thiol groups as well as in the near-UV CD, whereas under anaerobic condition the change in the near-UV CD is much less and SH-group environments remain unaltered. The sensitizer in this photoinduced change in conformation of the protein is very selective and specific.     

Cooling of a composite slab

A mixed boundary value problem associated with the diffusion equation, that involves the physical problem of cooling of an infinite parallel-sided composite slab, is solved completely by using the Wiener-Hopf technique. An analytical expression is derived for the sputtering temperature at the quench front being created by a cold fluid moving on the upper surface of the slab at a constant speed v. The dependence of the various configurational parameters of the problem under consideration, on the sputtering temperature, is rather complicated and representative tables of numerical values of this important physical quantity are prepared for certain typical values of these parameters. Asymptotic results in their most simplified forms are also obtained when (i) the ratio of the thicknesses of the two materials comprising the slab is very much smaller than unity, and (ii) the quench-front speed v is very large, keeping the other parameters fixed, in both the cases.     

Ferromagnetically coupled cobalt-benzene-cobalt: the smallest molecular spin filter with unprecedented spin injection coefficient

Here, we predict that the ferromagnetically coupled cobalt-benzene-cobalt system will act as the smallest molecular spin filter with unprecedented spin injection coefficient. To validate our in-silico observation, we have performed state-of-the-art nonequilibrium Green's function calculations and analyzed the density of states of cobalt at the relativistic and nonrelativistic level of theory. Remarkably, we found that unpaired 3d electrons of cobalt are not participating in the spin transport process like other transition metal containing multidecker complexes. Instead, an admixture of the outer-sphere 4s and 4p orbitals of cobalt along with the 2p orbital of carbon of the benzene moiety is contributing to the singly occupied highest molecular orbital in the majority spin channel that creates a path for coherent spin transport leading to the extremely high spin injection coefficient of the system. The absence of the 3d electrons of cobalt in the spin transport process has been carefully examined, and it was found that the nodal structure of the 3d orbital of cobalt is not at all suitable for bonding in the cobalt-benzene-cobalt system. The whole study indicates that the underlying mechanism of the spin filter action in cobalt-benzene-cobalt is completely distinctive from the other known materials.     

Measurement of the Diffusivity of Cesium Ion in Aqueous Rubidium Chloride Solution

For the first time cesium diffusivity in aqueous solutions of rubidium chloride is being reported here in the concentration range from 0.001 to 4.00 mol⋅dm⁻³. The measurement use a radioactive tracer technique employing a sliding cell mechanism. These diffusivity values were utilized to understand the transport mechanism of Cs ion in the RbCl–H₂O system using the Onsager-Gosting-Harned equation and the extended Debye-Hückel equation. The observed deviation between the theoretical and experimental diffusivities are explained by introducing the concept of Field-Dielectric-Gradient forces and energies that exist around an ion, which takes care of the finite size of the ion, ion-water interaction and the ion-ion interaction in a continuum basis.     

Simultaneous occurrence of energy transfer and photoinduced electron transfer in interactions of hen egg white lysozyme with 4-nitroquinoline-1-oxide

The carcinogenic drug 4-nitroquinoline-1-oxide (4NQO) has been found to bind with the protein hen egg white lysozyme as evident from fluorescence quenching experiments. The binding constant and stoichiometry have been determined. The values of the thermodynamic parameters indicate that the interaction is an enthalpy-driven spontaneous phenomenon. The experimental value of change in free energy is similar to that obtained from the docking study. The far UV circular dichroism spectra show some changes in the secondary structure of protein. The high value of bimolecular quenching constant leads to the possibility of Förster resonance energy transfer (FRET). Along with FRET, the photoinduced electron transfer (PET) from tryptophan residue of protein to 4NQO has also been evident from the transient absorption spectra obtained in laser flash photolysis experiments. The simultaneous occurrence of FRET and PET is the key factor for quenching of intrinsic fluorescence of the protein as it binds with the drug.