Development of Raman-shifted probe laser beam for plasma diagnosis using polaro-interferometer

Optical diagnostics of laser-produced plasma requires a coherent, polarized probe beam synchronized with the pump beam. The probe beam should have energy above the background emission of plasma. Though the second harmonic probe beam satisfies most of the requirements, the plasma emission is larger at the harmonic frequencies of the pump. Hence, at high intensities we need a probe beam at non-harmonic frequencies. We have set up a Raman frequency shifted probe beam using a pressurized hydrogen cell that is pumped by the second harmonic of the Nd glass laser that operates at only one Stokes line of 673.75 nm.     

Monte Carlo predictions of phase equilibria and structure for dimethyl ether + sulfur dioxide and dimethyl ether + carbon dioxide

A new force field for dimethyl ether (DME) based on the Lennard-Jones (LJ) 12-6 plus point charge functional form is presented in this work. This force field reproduces experimental saturated liquid and vapor densities, vapor pressures, heats of vaporization, and critical properties to within the statistical uncertainty of the combined experimental and simulation measurements for temperatures between the normal boiling and critical point. Critical parameters and normal boiling point are predicted to within 0.1% of experiment. This force field is used in grand canonical histogram reweighting Monte Carlo simulations to predict the pressure composition diagrams for the binary mixtures DME + SO(2) at 363.15 K and DME + CO(2) at 335.15 and 308.15 K. For the DME + SO(2) mixture, simulation is able to qualitatively reproduce the minimum pressure azeotropy observed experimentally for this mixture, but quantitative errors exist, suggesting that multibody effects may be important in this system. For the DME + CO(2) mixture, simulation is able to predict the pressure-composition behavior within 1% of experimental data. Simulations in the isobaric-isothermal ensemble are used to determine the microstructure of DME + SO(2) and DME + CO(2) mixtures. The DME + SO(2) shows weak pairing between DME and SO(2) molecules, while no specific pairing or aggregation is observed for mixtures of DME + CO(2).     

Synthesis and structure of transition metal complexes derived from a novel polynucleating oxaza macrocycle having diazine and phenoxo bridging components

Novel Co^II, Ni^II, Cu^II and Zn^II complexes of the polynucleating oxaza macrocyclic ligand (LH₄) derived from the 2:2 condensation of pyrazole-3,5-dicarbohydrazide and 2,6-diformyl-4-methylphenol have been synthesized. Ligand and complexes were characterized on the basis of elemental analysis, IR, ¹HNMR, UV–Visible, magnetic susceptibility, ESR and conductivity measurements, FAB-mass and thermal analysis. Present Zn^II and Cu^II complexes are binuclear in nature with octahedral geometry, where as Co^II and Ni^II complexes are tetranuclear with square-planar geometry. Cu^II and Co^II complexes are paramagnetic whereas Zn^II and Ni^II complexes are diamagnetic. Only the copper complex has shown redox property in the applied potential range while the ligand and other complexes are found to be electrochemically innocent.     

Electrodeposition of ZnO coatings from aqueous Zn(NO3)2 baths: effect of Zn concentration, deposition temperature, and time on orientation

Cathodic reduction of zinc nitrate solution results in the deposition of ZnO crystallites with a strong c-axis orientation. The orientation of crystallites can be switched to 10l (l?=?1, 2, 3) direction by varying the bath concentration (0.04–0.1?M) and the deposition conditions (T, 50–70?°C; t, 30–90?min). The range of concentrations yielding c-axis orientation can be widened at a high deposition temperature. At 0.1?M bath concentration and long deposition times, crystallites are oriented along 10l (l?=?3) direction. At low temperature (50?°C), 100 oriented nanostructured ZnO coatings are obtained (crystallite size, 20–35?nm). The c-axis-oriented crystallites grow as hexagonal columns perpendicular to substrate and 10l-oriented crystallites grow tilted at different angles to the substrate surface.     

Study of the Effect of the Interaction Between Kaolin and Surfactant Blend (AOS: APG C12) on the Solubility,Dispersibility, and Wetting Property of the Pesticide Granule

The extensive use of pesticides in agriculture in particular herbicides is a serious environmental threat. There is an urgent need to develop pesticide formulation that combines optimum bioactivity and minimum dosage. In the present article an attempt has been made to design granular formulation of one of the most commonly used herbicide, atrazine (AT). This potent herbicide along with kaolin as the carrier and suitable clay modifiers can be thought as one of the potential way of formulation keeping in view the desired dosage and bioavailability of the same. The process of granule formulation was carried out using the principle of rapid mix granulation. These granule formulations were then compared with the other formulation where the clay was not modified with the help of parameters such as dissolution rate, dispersion stability and wetting time. The study reveals a very positive effect of clay modifications on granules in terms of above mentioned quality parameters.     

Study of Solubilizing Capacity of Anionic Surfactants (AOS and SLS) in Spray-Dried Pesticide Formulation

The slow dissolution rate exhibited by sparingly water‐soluble pesticide is a major challenge in the pesticide development process. The aim of this study was to improve the dissolution rate of a sparingly water soluble model pesticide, Atrazine. Microparticles containing the model pesticide (atrazine) were produced by spray‐drying technique in the absence and presence of an anionic surfactant. Alpha olefin sulfonate (AOS) and Sodium lauryl sulfate (SLS) were chosen as the surfactants to improve the particle wetting and the dissolution rate. The spray dried particles were characterized by SEM and particle size analyzer and dissolution studies were carried out by USP XXIII paddle method. Also the effect of spray drying on atrazine was studied by DSC. The results obtained showed that the dissolution rate of the spray dried atrazine‐surfactant particles were significantly increased compared to the active. This proves that the better wetting characteristics conferred by the hydrophilic surfactant were responsible for the enhanced dissolution rate of the model pesticide. 50% water dispersible granules (WDG) of atrazine were also prepared by spray‐drying technique. The resulting granules had a unique combination of good flow ability and a good degree of dispersion.     

Simulation of gain-switched picosecond pulse generation from quantum well lasers

Circuit models for gain-switched quantum well laser diodes are developed and simulated using the circuit analysis program SPICE2. Effects of cavity length and number of wells on the output pulse shape are analysed. Picosecond pulses of 7 and 2 ps full-width at half-maximum (FWHM) are observed, corresponding to second and third quantized level transitions, respectively. A remarkable reduction in the output pulse width observed for the third quantized level transition, demonstrates the significance of higher sub-band transitions for ultrashort pulse generation.     

Synthesis, spectral characterization and biological activities of Mn(II) and Co(II) complexes with benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone

Mn(II) and Co(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone have been synthesized and characterized by the investigations of electronic and EPR spectra and X-ray diffraction. Based on the spectral studies, an octahedral geometry is assigned for the Mn(II) and Co(II) complexes. X-ray powder diffraction studies reveal that Mn(II) and Co(II) complexes have triclinic crystal lattices. The unit cell parameters of the Mn(II) complex are a=11.0469 ?, b=6.2096 ?, c=7.4145 ?, α=90.646°, β=95.127°, γ=104.776°, V=489.7 ?(3) and those of Co(II) complex are a=9.3236 ?, b=10.2410 ?, c=7.8326 ?, α=90.694°, β=99.694°, γ=100.476°, V=724.2 ?(3). When the free ligand and its metal complexes are subjected to antibacterial activity, the metal complexes are proved to be more active than the ligand. However with regard to in vitro antioxidant activity, the ligand exhibits greater antioxidant activity than its metal(II) complexes.     

Anion exchange reaction potentials as approximate estimates of the relative thermodynamic stabilities of Mg/Al layered double hydroxides containing different anions

Coatings of hydrotalcite-like nitrate-intercalated Mg/Al layered double hydroxides are electrochemically deposited on a Pt electrode by electrogeneration of base by reduction of a mixed metal nitrate aqueous solution. As-prepared coatings are stable to workup and function as rugged electrodes. The voltammetric response generated by anion exchange of intercalated nitrate for dissolved anions from solution under equilibrium conditions is employed to estimate the thermodynamic stabilities of the Mg/Al layered double hydroxides comprising different anions relative to the nitrate-containing phase. Among monovalent anions, the most stable is the fluoride-containing LDH (ΔG° = -48.7 kJ mol(-1)) relative to the nitrate-containing LDH. The stability in aqueous phase decreases as F(-) > Cl(-) > Br(-) > NO(2)(-) > NO(3)(-), whereas, among divalent anions, SO(4)(2-) (ΔG° = -8.7 kJ mol(-1)) > CO(3)(2-) (ΔG° = 14.3 kJ mol(-1)). The results of monovalent ions match well with the Miyata series, whereas the divalent anion series is at variance with the commonly held belief that carbonate-LDHs are more stable than sulfate-LDHs.