Enhancement of photocatalytic activity and regeneration of Fe-doped TiO2 (Ti1−xFexO2) nanocrystalline particles synthesized using inexpensive TiO2 precursor

Research on Chemical Intermediates - Fe-doped TiO2, Ti1?xFexO2 (x?=?0.00, 0.01, 0.03, 0.05, 0.07, and 0.09) photocatalysts with enhanced activity were synthesized via a...     

Determination of Essential Elements in Ayurvedic Medicinal Leaves by k0 Standardized Instrumental Neutron Activation Analysis

Elemental concentrations of a few medicinal leaves are determined by instrumental neutron activation analysis using the single comparator (k ₀) method. Data obtained for neem leaves, collected from two different places, have been used to see the effect of soil condition. The applicability of the method particularly for the simultaneous determination of Ca, Mg, V and Al in biological matrices has been evaluated in terms of the detection limit, precision and accuracy. The method was validated by analysing the NIST Standard Reference Material (SRM-1571) and it was found that the elemental concentrations measured in SRM-1571 are within ±10% of the reported values.     

A comparative study of a polyindole-based microelectrochemical transistor in aqueous and non-aqueous electrolytes

The behaviour of a polyindole-based microelectrochemical transistor in aqueous and non-aqueous electrolytes is described. The polyindole film was grown onto two closely spaced (100 μm) platinum microelectrodes by anodic oxidation of indole (10 mM) from 0.1 M tetrabutylammonium perchlorate in dichloromethane at 1.1 V vs. Ag/AgCl. The polymerization was carried out for a sufficiently long time in order to connect both Pt microelectrodes, which operated as a transistor when immersed in an electrolytic solution. In this transistor, one microelectrode was a “source” and the other a “drain”; the Ag/AgCl wire reference electrode was used as a “gate”. The drain current (current between source and drain) was modulated by varying the gate potential (potential between source and gate) at a fixed drain potential (potential between source and drain). The transconductances of the transistor were estimated as 0.98 mS/cm and 20.6 mS/cm of channel width (separation between two microelectrodes) in aqueous and non-aqueous solutions, respectively. Received: 6 April 1999 / Accepted: 24 August 1999     

Optical anisotropy and the direction of polarization of exciton emissions in a semiconductor quantum dot:Effect of heavy-and light-hole mixing

The dependence of the directions of polarization of exciton emissions, fine structure splittings(FSS), and polarization anisotropy on the light-and heavy-hole(LH–HH) mixing in semiconductor quantum dots(QDs) is investigated using a mesoscopic model. In general, all QDs have a four-fold exciton ground state. Two exciton states have directions of polarization in the growth-plane, while the other two are along the growth direction of the QD. The LH–HH mixing does affect the FSS and polarization anisotropy of bright exciton states in the growth-plane in the low symmetry QDs(e.g., C_(2V),C_S, C_1), while it has no effect on the FSS and polarization anisotropy in high symmetry QDs(e.g., C_(3V), D_(2d)). When the hole ground state is pure HH or LH, the bright exciton states in the growth-plane are normal to each other. The LH–HH mixing affects the relative intensities and directions of bright exciton states in the growth-plane of the QD. The polarization anisotropy of exciton emissions in the growth-plane of the QD is independent of the phase angle of LH–HH mixing but strongly depends on the magnitude of LH–HH mixing in low symmetry QDs.     

Extended time range modeling of myelin growth

When some poorly water-soluble solid surfactants are contacted with water, several microstructures are observed as part of the dissolution process of the surfactants in water. One such microstructure called "myelin," which is observed when a surfactant like phosphatidylcholine is contacted with water, is the subject of this paper. In this study we have used video microscopy to investigate myelin growth over a wide time range, namely 0.25-700 s, and found that existing models do not correctly express myelin growth over extended time ranges. When studied over a wide time range, the myelin growth was found to evolve over three distinct regimes, namely ballistic, diffusional, and subdiffusional regimes. The underlying growth models are physically explained and mathematically expressed. A relationship is derived between the width of myelin and the growth rate at long times. The estimated width of myelin is consistent with experiments.     

Spontaneously broken spacetime symmetries and Goldstone's theorem

Goldstone's theorem states that there is a massless mode for each broken symmetry generator. It has been known for a long time that the naive generalization of this counting fails to give the correct number of massless modes for spontaneously broken spacetime symmetries. We explain how to get the right count of massless modes in the general case, and discuss examples involving spontaneously broken Poincaré and conformal invariance.     

Heat capacity and thermodynamic properties of the alkali metal compounds in the temperature range 300–800 K. I. Cesium and rubidium molybdates

The heat capacities of cesium and rubidium molybdates, Cs₂MoO₄ and Rb₂MoO₄, have been measured by differential scanning calorimetry (DSC) in the temperature range 300–800 K. These values have been combined with published low-temperature heat capacity data for Cs₂MoO₄ to obtain thermodynamic functions to 800 K. For Rb₂MoO₄, however, these functions could not be calculated because low-temperature heat capacities are unavailable. Instead, only heat capacity data are reported.