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.     

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.     

Vibration of piezoelectric elements surrounded by fluid media

In this paper we analyse vibrational characteristics of piezoceramic shells surrounded by acoustic media. Main results are presented for radially polarized piezoceramic PZT5 elements of hollow cylindrical shapes. The coupling in the radial direction between the solid and the acoustic media is accounted for indirectly, via impedance boundary conditions. The model based on such impedance boundary condition approximations offers a robust simplified alternative to a full scale fluid-solid interaction modelling. By using this model, we analyse numerically the influence of the boundary conditions imposed in the axial direction for long, medium, and short (disk-like) piezoceramic elements.     

Growth and physical properties of a new chiral open-framework crystal for NLO applications: Cesium hydrogen l-malate monohydrate

Cesium hydrogen l-malate monohydrate, CsH(C₄H₄O₅)·H₂O, is a new chiral open-framework semi-organic crystalline material with a second-harmonic generation efficiency one order of magnitude greater than KDP. Single crystals of this new material have been grown by the conventional slow cooling technique from aqueous solution. Grown crystals display both platy and prismatic morphologies depending on the imposed supersaturation. Hardness values measured using Vickers hardness indenter show considerable anisotropy. The resistivity behavior at room temperature and above, places the crystal between an ionic conductor and a dielectric. The single-crystal SHG efficiency estimated through Maker fringes experiment gives d_eff which is 4.24 times that of KDP. Single and multiple shot experiments performed on the grown crystals for the fundamental and second harmonic of pulsed Nd:YAG laser (1064 and 532 nm) show that it exhibits a high laser damage threshold which is a favorable property for nonlinear optical applications.     

Small Form Factor Fiber Optic Transceiver Module for High-end SONET/SDH Application

2.5Gb/s SONET/SDH applications with reach up to 80km in standard SMF fiber, is presented. Introduction Due to the trend towards higher port densities in high-capacity communication systems,Small Form Factor (SFF) Transceivers are becoming popular [1]. Originally, SFF transceivers were designed to address short reach (2km) and intermediate reach(15km) applications using PIN receivers [2]. We have developed SFF transceivers for the high-end SONET/SDH space (2.5Gb/s speed for 40km and 80km reach). This part of the SONET/SDH space is unique due to the need for Avalanche Photo Diode (APD) based receiver within a SFF footprint, and still maintaining a good transceiver performance is a real challenge.     

Measurement of virtual mass and drag coefficients of a disk oscillating sinusoidally in a two-phase mixture

This paper presents an experimental determination of the virtual mass and drag coefficients of a disk oscillating sinusoidally in a two-phase mixture of air flowing through stagnant water. The purpose of this experiment was to determine the importance of virtual mass on the transient response of an INEL-type drag-disk flow meter.The results indicate that for a given void fraction, the virtual mass coefficient increases, and the drag coefficient decreases, with increasing amplitude parameter. Also, for a given amplitude parameter, the virtual mass coefficient decreases, and the drag coefficient increases, with increasing void fraction.Based on the measured virtual mass coefficients, it was concluded that when an INEL-type drag-disk is used for the measurement of transient two-phase flows, virtual mass effects may be neglected in the analysis of its response without appreciable error.