A simple spectrophotometric method for determination of isoxsuprine hydrochloride in pharmaceuticals

A spectrophotometric method has been developed for the determination of isoxsuprine hydrochloride and its dosage forms, based on its coupling reaction with diazotized sulphanilic acid. The yellow chromophore has an absorption maximum at 440 nm. Beer's law holds over the range 0.8-8 mu/ml in the final solution.     

Direct asymmetric organocatalytic Michael reactions of alpha,alpha-disubstituted aldehydes with beta-nitrostyrenes for the synthesis of quaternary carbon-containing products

[reaction: see text] Direct asymmetric catalytic Michael reactions have been performed using chiral-amine/acid bifunctional catalysts. Performed with 0.3 equiv of (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine and 0.3 equiv of trifluoroacetic acid as the catalyst, the reaction of alpha,alpha-dialkylaldehydes with (E)-beta-nitrostyrene provided the alpha,alpha-dialkyl Michael products in up to 96% yield with up to 91% ee. With respect to enantioselectivity, l-proline was a poor catalyst of this class of Michael reactions.     

Acid activated montmorillonite and vermiculite clays as dehydration and cracking catalysts

Treatment of montmorillonite and vermiculite with hydrochloric acid results in an overall increase in acidity and acidic sites. IR and DSC studies of base adsorbed catalysts have revealed the heterogeneity of surface acidity on the activated catalysts. Clay catalysts have been found to dehydrate 1-butanol to 1-butene, which directly isomerizes tocis- andtrans-2-butenes, confirming the presence of Lewis and Brönsted acid sites. Cumene cracking studies using the clay catalyst also confirm the presence of Brönsted acid sites. The temperature and concentration of acid have been found to have a significant influence on the catalytic activity.     

Synthesis and characterization of sol–gel derived glass-ceramic and its corrosion protection on 316L SS

Glass-ceramic was prepared by sol–gel method using Ca(NO₃)₂·4H₂O and P₂O₅ as Ca and P precursors, respectively. In order to improve the bioactivity of the implant material, glass-ceramic (β-Ca₂P₂O₇) coating was developed on 316L SS substrate by spin coating method. Coating was annealed at different temperatures and its corrosion resistance was evaluated by electrochemical polarization and impedance analysis using Ringer’s solution as electrolyte. The results from the present study, show excellent corrosion resistance for coated 316L SS, corroborated by the high values of charge transfer resistance from impedance analysis and higher breakdown and repassivation potential with the corresponding lower current density from polarization measurements. Based on the results, the glass-ceramic coating on 316L SS can be considered as a corrosion resistant material.     

Inhibition of mild steel corrosion by Morinda tinctoria leaves extract in sulphuric acid medium

The corrosion inhibition of mild steel in 0.5 M sulphuric acid by aqueous and acid extracts of leaves of Morinda tinctoria was studied using weight loss, colorimetric and electrochemical techniques. Results obtained indicate that both the extracts are effective in sulphuric acid medium and the efficiency decreases with increase in temperature. Added halide additives improve the efficiency of the inhibitor. From the thermodynamic, spectral, and surface analyses, the nature of adsorption has been found out.     

Recent study of nanomaterials prepared by inert gas condensation using ultra high vacuum chamber

The ultra high vacuum chamber was developed in the Department of Nuclear Physics, University of Madras with the funding from DST, India. This UHV chamber is used to prepare nanocrystalline materials by inert gas condensation technique (IGCT). Nanocrystalline materials such as PbF₂, Mn²⁺-doped PbF₂, Sn-doped In₂O₃ (ITO), ZnO, Al₂O₃, Ag₂O, CdO, CuO, ZnSe:ZnO etc., were prepared by this technique and characterized. Results of some of these materials will be presented in this paper. In solid-state²⁰⁷Pb NMR on PbF₂ a separate signal due to the presence of grain boundary has been observed. The structural phase transition pressure during the phase transformation from the cubic phase to orthorhombic phase under high pressure shows an increase with the decrease in grain size. Presence of electronic centres in nanocrystalline PbF₂ is observed from Raman studies and the same has been confirmed by photoluminescence studies. Al₂O₃ was prepared and⁵⁶Fe ions were implanted. After implantation segregation of⁵⁶Fe ions was examined by SEM. The oxidation properties of ITO were studied by HRTEM. As against the expectation of oxide coating on individual nanograins of In-Sn alloy, ITO nanograins grew into faceted nanograins on heat treatment in air and O₂ atmosphere. The growth of ITO under O₂ atmosphere showed pentagon symmetry. The PMN was initially prepared by solid-state reaction. Further, this PMN relaxor material will be used to convert into nanocrystalline PMN by IGCT with sputtering and will be studied     

Stress Field Evolution under Mechanically Simulated Hull Slamming Conditions

The effect of repeated loading from mechanically simulated hull slamming on foam core sandwich composites was investigated utilizing a novel technique that simultaneously measured temperature and displacement while cyclic loading occurred. Thermoelastic Stress Analysis (TSA) and Digital Image Correlation (DIC) techniques were combined using a single infrared camera for characterization of the foam core. Improved stress fields with TSA results were found through deformation compensation. Initial work approximating hull slamming conditions mechanically utilizing a custom device were performed. Mechanically loading offers several benefits over water impact investigations, including easy access to the sample during the slamming event, an unobstructed optical path, and accelerated testing. Evolving stress fields under long-duration, repeated simulated hull slamming loading were observed around a growing delamination crack between the foam core and skin.     

Simultaneous bioanalysis and pharmacokinetic interaction study of acebrophylline,levocetirizine and pranlukast in Sprague–Dawley rats

The combination of acebrophylline (ABP), levocetirizine (LCZ) and pranlukast (PRN) is used to treat allergic rhinitis, asthma, hay‐fever and other conditions where patients experience difficulty in breathing. This study was carried out with the aim of developing and validating a reverse‐phase high‐performance liquid chromatographic bioanalytical method to simultaneously quantitate ABP, LCZ and PRN in rat plasma. The objective also includes determination of the pharmacokinetic interaction of these three drugs after administration via the oral route after individual and combination treatment in rat. Optimum resolution between the analytes was observed with a C₁₈ Kinetex column (250 mm × 4.6 mm × 5 μm). The chromatography was performed in a gradient elution mode with a 1 mL/min flow rate. The calibration curves were linear over the concentration range of 100–1600 ng/mL. The intra‐ and inter‐day precision and accuracy were found to be within acceptable limits as specified in US Food and Drug Administration guideline for bioanalytical method validation. The analytes were stable on the bench‐top (8 h), after three freeze–thaw cycles, in the autosampler (8 h) and as a dry extract (?80°C for 48 h). The statistical results of the pharmacokinetic study in Sprague–Dawley rats showed a significant change in pharmacokinetic parameters for PRN upon co‐administration of the three drugs.