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1

Determination of Deltamethrin in Mice Plasma and Immune Organs by Simple Reversed-Phase HPLC

Kumar A., Dubey R. K., Kant K., Sasmal D., Ghosh M., Sharma N.

Acta Chromatographica

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2016

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Vol. 28, no. 2

193--206

EN

Deltamethrin, a well-known type 2 synthetic pyrethroid insecticide, is a widespread environmental toxicant. It has potential to accumulate in body fluids and tissues due to its lipophilic characteristics. The immune system is among the most sensitive targets regarding toxicity of environmental pollutants. Various methods are available in the literature to analyze deltamethrin (DLM) concentration in plasma and tissues, but regarding the immune organs, only one gas chromatography–tandem mass spectrometry (GC–MS/MS) method (on spleen tissues) has been reported. In the present investigation, a rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed and validated to determine DLM concentration in plasma, thymus, and spleen using zaleplone as an internal standard. Liquid chromatography (LC) separation is performed on an Agilent Zorbax® C8 column (250 mm × 4.6 mm, i.d., 5 μm) with isocratic elution using a mobile phase consisting of acetonitrile–5 mM KH2PO4 (70:30, v/v) at a flow rate of 1 mL min−1. The lower limit of quantification (LLOQ) for DLM is 10 ng mL−1 (plasma, thymus, and spleen). The method has been validated in terms of establishing linearity, specificity, sensitivity, recovery, accuracy, and precision (intra- and inter-day) and stabilities study. This validated method was successfully applied to a pharmacokinetic and tissue distribution study of DLM in mice.

2

Quantitative analysis of α-CL-20 polymorphic impurity in ε-CL-20 using Dispersive Raman Spectroscopy

Ghosh M., Venkatesan V., Sikder N., Sikder A. K.

Central European Journal of Energetic Materials

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2013

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Vol. 10, no. 3

419--438

EN

α-CL-20 polymorphic impurity in ε-CL-20 studies have been carried out using Dispersive Raman Spectroscopy. ε-, β-, α- and γ-CL-20 polymorphs were produced using crystallization methods with sample recovery from the solution being >90%, and chemical purity of about 99%. The polymorphs prepared were characterized using Dispersive Raman Spectroscopy over the Raman shift region of 100-3500 cm-1 using a 514 nm argon ion laser. The experimental studies were supported by ab initio computations performed at B3LYP level using a 6-31+G** basis set. The computed vibrational frequencies of the CL-20 conformers correspond to the ε, β and α or γ-CL-20 polymorphs when compared with the observed frequencies. α-CL-20 shows a distinct feature at 280 cm-1 as compared with those of the ε-CL-20 polymorph. Using Dispersive Raman Spectroscopy, a linear relationship was demonstrated for the absolute peak height and absolute peak area ratio of α-CL-20 versus the weight percent of α-CL-20. This method enables a detection limit of this polymorphic impurity down to 2 wt%.

3

Surface Coating of Cyclotetramethylenetetranitramine (HMX) Crystals with the Insensitive High Explosive 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB)

Nandi A. K., Ghosh M., Sutar V. B., Pandey R. K.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 2

119-130

EN

A method to crystallize the thermally stable, insensitive high explosive, 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) onto the surface of another high explosive cyclotetramethylenetetranitramine (HMX) crystal is described. Amination of 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) in toluene produces TATB which is precipitated by a reactive crystallization process. When the reaction is carried out in the presence of HMX, TATB crystals are found to be deposited onto the HMX crystal surface. This phenomenon was utilized to obtain in situ surface coating of HMX crystals with TATB. Both the conventional amination and the sonochemical amination methods, using dry ammonia (NH3) gas and ammonium hydroxide (NH 4 OH) respectively as the aminating agents, were studied. The coated materials were characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Simultaneous Thermal Analysis (STA) and sensitivity tests. The results were compared with those of the virgin materials. Sonochemical amination provided a uniform coating of the HMX crystals. Coated HMX has shown substantial friction insensitivity gain as compared to uncoated HMX. However there is a drop in impact insensitivity in the coated materials.

4

Formation of Boric Acid by Surface Oxidation of Amorphous Boron Powder: Characterization and Quantitative Estimation

Nandi A. K., Ghosh M., Newale S. P., Jadhav A. J., Prasanth H., Pandey R. K.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 4

387-398

EN

Amorphous Boron Powder (ABP) is used as a fuel in air breathing propulsion systems due to its high gravimetric and volumetric heat value. ABP is sensitive to air and undergoes slow oxidation during storage and handling, leading to the formation of a boric acid layer on the particle surface. This paper describes an analytical method for the estimation of boric acid in ABP. In-house samples obtained from the pilot plant of this laboratory, as well as commercial samples, were assayed for their boric acid content. The study is substantiated by characterization of the ABP samples by SEM with EDX and FTIR. The ageing characteristics of in-house boron powder was also studied.

5

Thermo-mechanical forming of sheet metal -- modelling of warm forming, heat treatments and transformations

Van Den Boogaard A. H., Kurukuri S., Ghosh M., Miroux A. G.

Computer Methods in Materials Science

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2009

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Vol. 9, No. 1

5-11

EN

Although basically all sheet forming processes are thermo-mechanical forming processes, the influence of temperature changes can most often safely be ignored. Two cases are considered, in which the interaction between thermal and mechanical behaviour cannot be neglected: 1. if the material is heated or cooled with the purpose to get different mechanical properties and 2. if the material properties vary considerably in the range between 20 and 100 °C, which is the range in industrial sheet forming processes without external heating or cooling. An example of the first one is temperature enhanced forming of aluminium sheet. In this process, parts of the tools are heated and other parts are cooled, in order to increase the formability. For simulations, this requires a material model that is suitable for the complete range of temperatures between 20 and 250 °C. Three models: a completely phenomenological model, the Bergström model and the Alflow model are evaluated with respect to temperature enhanced deep drawing of cylindrical cups of both Al-Mg and Al-Mg-Si alloys. A yet unexplained observation in experiments was that the earing profile changed between low temperature an elevated temperature deep drawing. Another type of temperature influence to enhance the formability of aluminium is an intermediate annealing step. Here, the thermal and mechanical loading is separated in time, but still they influence eachother, especially when aging materials are used. Experiments on, and models for an Al-Cu alloy are presented. The initial approach to completely reset the mechanical material properties after a heat treatment needed only very little correction. An example of the second type is the forming of austenitic stainless steels. Although the temperature dependence of austenite is not significant in ordinary industrial sheet forming situations, the material experiences a strain induced martensitic transformation which is highly sensitive to the temperature, exactly in the temperature range which is industrially the most common. Although progress is recently made in micro-scale modeling of the martensitic transformation, including transformation induced plasticity; these models are not feasible for full-scale forming simulations. Therefore, macroscopic models are developed that model the most relevant aspects in deep drawing: temperature, strain and stress dependent transformation and the influence on the macroscopic mechanical behaviour. The influence of stress is experimentally determined with a biaxial testing machine, in which several strain paths between simple shear and plane strain can be imposed.

PL

Temperatura oraz rozkład prędkości odkształcenia podczas formowania aluminium na ciepło charakteryzują się duża niejednorodnością. Wykorzystywane do analizy modele naprężenia uplastyczniającego powinny uwzględniać wpływ tych niejednorodności. Opracowany w niniejszej pracy fizyczny model Nes wykorzystano do symulacji tłoczenia aluminium AA6061-T4 w warunkach odkształcenia na ciepło. W trakcie analizy zaobserwowano znaczące różnice w kształcie wypływki uzyskanej podczas odkształcenia w temperaturze pokojowej oraz 250 °C. Analiza z wykorzystaniem modelu plastyczności kryształów wykazała aktywności dodatkowych systemów poślizgu w podwyższonych temperaturach. W pracy przedstawiono wyniki analizy numerycznej dla procesów rozciągania oraz tłoczenia.

6

Shear wave interaction with a pair of rigid strips embedded in an infinitely long elastic strip

Pramanik R., Pal S., Ghosh M.

Journal of Technical Physics

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1999

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Vol. 40, no 1

31-44

EN

In this paper, the problem of diffraction of normally incident SH wave by two co-planar finite rigid strips placed symmetrically in an infinitely long isotropic elastic strip perpendicular to the lateral surface is in maritime air and predicted scattering coef- of the elastic strip has been treated. The mixed boundary value problem gives rise to the determination of the solution of triple integral equations which finally have been reduced to the solution of a Fredholm integral equation of second kind. The equation has been solved numerically for low frequency range.