Quaternary hydrotalcite-like precursors containing Mg(II)Pd(II)Cu(II)Al(III) with (Pd + Cu + Mg)/Al ≈ 3 and varying Pd/Cu molar ratios were prepared by coprecipitation of metal nitrates at constant
pH. The precursors and their calcined products were characterized by elemental analysis, powder XRD, TG-DTA, FT-IR diffuse
reflectance, TPR and N2 physisorption. Powder XRD indicated the formation of hydrotalcite of good crystallinity as the structure for all the precursors;
the crystallinity decreased with increase of Pd2+ and Cu2+ in the Mg–Al brucite like layer. Thermal decomposition of HT-precursors at intermediate temperatures led to amorphous mixed
oxides, PdCu/MgAl(O), which on reduction yielded a bi-functional catalyst, Pd0Cu0/MgAl(O). The resulting catalysts with acid, base and hydrogenating sites were highly effective and selective for the one-step
synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen under mild conditions. Addition of copper with Pd inhibited
the formation of hydrogenated by-products, propane-2-ol (IPA) and 4-methyl-pentane-2-ol (MIBA), which resulted an increase
of MIBK selectivity and also the stability of the catalysts. A proper balance between acid-base and metallic sites was paramount
for high catalytic performance.
A simple chromatographic procedure for clean separation of the important radionuclide,99m Tc, in the equilibrium mixture,99Mo−99mTc, has been demonstrated. Separation of pure99mTc has been achieved by preferential extraction of the radioisotope through an anion exchange resin column of Amberlite IRA-410
using Na-ascorbate solution at pH 7 as an eluent. The radiochemical purity of the separated radiotracer has been verified
by taking recourse to γ-ray spectrometry. The potentiality of the developed procedure lies in the facts that the eluting agent,
ascorbic acid, itself h got its own biomedical importance as Vitamin C and the concerned radioisotope can be obtained in both
Tc(IV) and Tc(VII) states as per requirement for diagnostic purposes.
The potential use of ascorbic acid as a complexing reagent in the separation and preconcentration of rare earth elements (REE) in geological materials in a suitable solid matrix has been demonstrated. Traces of REE from some USGS standard rock samples, viz., GSP-1, G-2, AGV-1 and PCC-1, have been separated after acid dissolution in two ways: (1) by ion exchange chromatography on Dowex 50×8 column and Na-ascorbate as eluent and (2) by direct complexation with ascorbic acid under specific experimental conditions. The separated REE were coprecipitated with the non isotopic diluent, calcium fluoride, before neutron activation analysis. Radiometric determinations showed that the overall recovery of REE in both cases was practically quantitative.
A simple ion exchange procedure for clean separation of the biomedically important radionuclide,90Y, in the equilibrium mixture,90Sr–90Y, has been demonstrated. Separation of90Y in the carrier-free state has been achieved by preferential elution of the radiotracer through a cation exchange resin column of Dowex-50W-X8 with freshly prepared Na-ascorbate solution of <1% concentration at pH7. The radionuclidic purity of the separated90Y has been verified by taking recourse to the studies of beta decay curves. The procedure developed has the added advantage that the complexing reagent, ascorbic acid, itself has got its own biomedical importance as vitamin C and the technique can also conveniently be used as a generator for the isotope90Y.
[NiL3]X2 (where L=N-phenylethane-1,2-diamine and X=I− and ClO4−), [NiL2X2] (X is Cl−, Br−, NCS−, 0.5SO42− or 0.5SeO42−) and [NiL2(H2O)2](NO3)2 have been synthesized from solution and their thermal study has been carried out in the solid phase. [NiL2Cl2] upon heating undergoes irreversible endothermic phase transition (142–152C, ΔH=0.35 kJ mol−1) without showing any visual colour change. This phase transition is assumed to be due to conformation changes of the diamine
chelate rings. NiLCl2 and NiL2.5I2 have been prepared pyrolytically from [NiL2Cl2] and [NiL3]I2 respectively in the solid state. [NiL2(H2O)2](NO3)2 upon heating undergoes deaquation-anation reaction without showing any visual colour change. [NiL2X2] (X is Cl−, Br−, NCS−), [NiL2(H2O)2](NO3)2 and [NiL2(NO3)2] possess trans-octahedral configuration, whereas, [NiL2X2] (X is 0.5SO42− or 0.5SeO42−) are having cis-octahedral configuration. Amongst the complexes, only NiLCl2 shows unusually high (5.1 BM at 27C) magnetic susceptibility value.
Studies on the distribution of various oxidation states of recoil sulphur formed by35Cl(n, p)35S reaction in the alkali halides, namely, NaCl, KCl and RbCl have been made. A suitable anion exchange method using Amberlite
IRA-410 in the chloride form has been described for rapid separation of the various radiosulphur species. The elution was
carried out by means of nitrate solutions. The observed results on the effect of cation environment in affecting the distribution
of radioactive sulphur amongst its various oxidation states were discussed on the basis of electron affinity and ionic size
of the metal ion in question.
A simple solvent extraction procedure for an effective separation of traces of tantalum from rock phosphate samples has been
developed and used in its determination through neutron activation analysis. The tantalum contents in the samples were found
to be about 3.10−7%.
Autophagy is a catabolic process through which damaged or long-lived proteins, macromolecules and organelles are degraded using lysosomal degradative machinery. Since cardiac myocytes are terminally differentiated, the role of autophagy is essential to maintain the homeostasis of the myocardium. Autophagy supplies nutrients for the synthesis of essential proteins during starvation and thus helps to extend cell survival. Although autophagy is non-selective, under oxidative conditions it effectively removes oxidatively damaged mitochondria, peroxisomes and endoplasmic reticulum. Thus, autophagy can protect the cells from apoptosis and other major injuries, and it is considered to be in the cross-road between cell death and survival. However, excess autophagy can destroy essential cellular components and lead to cell death. The function of autophagy in normal and in the conditions of cardiac diseases such as heart failure, cardiomyopathy, cardiac hypertrophy, and ischemia-reperfusion injury is discussed.
Effective separation of the congeneric pair of elements, zirconium and hafnium and also niobium which was in admixtures with zirconium as daughter in its isotopic form were achieved through reversed phase column and paper extraction chromatographic procedures using di-(2-ethylhexyl)phosphoric acid (HDEHP) as the liquid exchanger. In reversed phase column chromatographic separation, the tracers,95Zr,95Nb and175,181Hf, were extracted by HDEHP impregnated on kieselguhr and were sequentially eluted with 6N H2SO4+xN oxalic acid+H2O2(where x=0.1, 0.5 and 2). Similarly, in reversed phase paper chromatographic study in which a coating of HDEHP on Whatman No. 1 chromatographic paper was used as stationary phase, the mobile phase, 18N H2SO4+0.1N oxalic acid + H2O2, helped in separating the elements with favorable separation factors. Under the optimal conditions, the separation and decontamination of the elements in both methods were found to be quantitative, as verified by -spectrometric studies.