A rapid chromatographic method for the estimation of thorium in rocks, soils and low grade ores

Summary A simple and rapid field Chromatographic method for the determination of thorium in ppm quantities in rocks, soils and low grade ores using paper strip chromatography is described. An aliquot of an hydrochloric acid solution of the sample is taken on a special paper (Chromatographic paper of C.R.L./l grade) and the paper is then placed into a beaker containing the solvent mixture consisting of methyl alcohol, acetone, 2-thenoyl trifluoroacetone and hydrochloric acid in the ratio 12 ml6 ml0.04 g2 ml (13) respectively.A saturated alcoholic solution of alizarin atph 2.8-2.4 is used as developing reagent.This method is applicable to samples containing from 0.2 ppm to 1000 ppm of thorium.

---

Zusammenfassung Eine einfache und schnell durchführbare Feldmethode zur papierchromatographischen Bestimmung von ppm-Mengen Thorium in Gesteinen, Böden und Erzen niederen Gehaltes wird beschrieben. Hierbei wird ein Anteil der salzsauren Probelösung auf ein Spezialpapier (C.R.L./ 1 grade) aufgebracht und dieses in einem Becherglas mit einem Gemisch aus Methanol, Aceton, 2-Thenoxyltrifluoraceton und Salzsäure (12 ml 6 ml0,04 g2 ml [13]) chromatographiert. Zur Entwicklung dient eine gesättigte alkoholische Alizarinlösung (ph 2,8-2,4). 0,2–1000 ppm Thorium können nach diesen Verfahren bestimmt werden.

     

XRD and bulk magnetic studies on Ni-Cd and Ti doped Ni-Cd ferrites

For the ferrites Ni _x Cd_1–x Fe₂O₄ (x=0.3, 0.4,1) the lattice parameter, grain size, electrical resistivity, initial permeability, Curie temperature and squareness of the magnetization curve were measured. The results are discussed in terms of the model of the canted spin structure taking into account the domain structure of the polycrystalline ferrite.     

A single amino acid Gly-tag enables metal-free protein purification

Analytically pure proteins are indispensable for diverse applications, including therapeutics. Here, we report a methodology where a single amino acid, glycine, enables metal-free protein purification. This robust platform is enabled by a Gly-tag resin for site-specific capture, enrichment, and release through chemically triggered C–C bond dissociation by resonance-assisted electron density polarization.

Gly-tag resin precisely captures and releases a protein with one glycine at the N-terminus. The user-friendly protocol delivers analytically pure protein free of metal contaminants.     

Spectroscopic studies on the mode of interaction of an anticancer drug with bovine serum albumin

The mechanism of interaction of vinblastin sulphate (VBS) with bovine serum albumin (BSA) has been reported. Association constant for VBS-BSA binding was found to be 3.146+/-0.06 x 10(4) M(-1). Stern-Volmer analysis of fluorescence quenching data showed that the fraction of fluorophore (protein) accessible to the quencher (drug) was close to unity indicating thereby that both tryptophan residues of BSA are involved in drug-protein interaction. The rate constant for quenching, greater than 10(10) M(-1) S(-1), indicated that the drug-binding site is in close proximity to tryptophan residues of BSA. Binding studies in the presence of an hydrophobic probe, 8-anilino-1-naphthalein-sulphonic acid, sodium salt (ANS) indicated that there is hydrophobic interaction between VBS and probe and they do not share common sites in BSA. Thermodynamic parameters obtained from data at different temperatures showed that the binding of VBS to BSA involves predominant hydrophobic forces. The effects of some additives and paracetamol on binding of VBS-BSA have also been investigated. The CD spectrum of BSA in presence of VBS shows that the binding of VBS leads to change in the helicity of BSA.     

Asymmetric synthesis of (+)-stagonolide C and (−)-aspinolide A via organocatalysis

A new enantioselective synthesis of two important fungal metabolites, (+)-stagonolide C and (?)-aspinolide A, has been described from readily available raw materials. Proline catalyzed asymmetric α-aminooxylation and Jorgensen’s epoxidation of aldehydes are the key reactions employed in the introduction of chirality. The formation of the 10-membered lactone core structure was finally accomplished via Steglich esterification and ring closing metathesis reactions.     

Fully Diastereoselective Synthesis of Polysubstituted,Functionalized Piperidines and Decahydroquinolines Based on Multicomponent Reactions Catalyzed by Cerium(IV) Ammonium Nitrate

The cerium(IV) ammonium nitrate (CAN)‐catalyzed, three‐component reaction between primary amines, β‐dicarbonyl compounds, and α,β‐unsaturated aldehydes in ethanol heated to reflux, constitutes a general, one‐pot synthesis of 1,4‐dihydropyridines. Their reduction with sodium triacetoxyborohydride furnished piperidine derivatives bearing up to five substituents with full diastereoselectivity in a hitherto inaccessible stereochemical arrangement. The reaction proceeded with no significant loss of enantiomeric purity under mild reduction conditions that are compatible with several functional groups that are normally sensitive to reduction. Octahydroquinolin‐5‐one derivatives, which were prepared by a modified version of the initial multicomponent reaction, were not suitable substrates for the sodium triacetoxyborohydride mediated reduction, but they were transformed into the corresponding decahydroquinolines, including a precursor of the amphibian alkaloid pumiliotoxin C, by catalytic hydrogenation under a variety of conditions.     

Ion beam synthesis of metal-quantum dots for photonic applications

Although electronics technologies have made great advances in device speed, optical devices can function in the time domain inaccessible to electronics. In the time domain less than 1 ps, optical devices have no competition. Photonic or optical devices are designed to switch and process light signals without converting them to electronic form. The major advantages that these devices offer are speed and preservation of bandwidth. The switching is accomplished through changes in refractive index of the material that are proportional to the light intensity. The third-order optical susceptibility, χ⁽³⁾, known as the optical Kerr susceptibility which is related to the non-linear part of the total refractive index, is the nonlinearity which provides this particular feature. Future opportunities in photonic switching and information processing will depend critically on the development of improved photonic materials with enhanced Kerr susceptibilities, as these materials are still in a relatively early stage of development. Different glass systems are now under investigation to increase their nonlinearity by introducing a variety of modifiers into the glass-network. Ion implantation is an attractive method for inducing colloid formation at a high local concentration unattainable by the melt-glass fabrication process and for confining the non-linearities to specific patterned regions in a variety of host matrices. Recent works on metal-ion implanted colloid generation in bulk fused silica glasses have shown that these nanocluster-glass composites under favourable circumstances have significant enhancement of χ⁽³⁾ with picosecond to femtosecond temporal responses.     

A Novel Synthesis and Characterization of Titanium Superoxide and its Application in Organic Oxidative Processes

A novel, exceptionally stable titanium superoxide radical ion was prepared and its structure determined by FTIR, ESR, Raman spectroscopy, X-ray diffraction, thermogravimetric/differential thermal analysis and elemental analysis. This heterogeneous catalyst has been found to be effective for the selective oxidation of aromatic amines and phenols to the corresponding nitro aromatics and p-quinones, respectively. In addition, this non-toxic, inexpensive and reusable catalyst has also been used in aminobromination of olefins, which proceed to give the 1, 2-bromoaminated anti-Markovnikov product. A brief account of these results is summarized in this review.     

Ion-water clusters, bulk medium effects, and ion hydration

Thermochemistry of gas-phase ion-water clusters together with estimates of the hydration free energy of the clusters and the water ligands are used to calculate the hydration free energy of the ion. Often the hydration calculations use a continuum model of the solvent. The primitive quasichemical approximation to the quasichemical theory provides a transparent framework to anchor such efforts. Here we evaluate the approximations inherent in the primitive quasichemical approach and elucidate the different roles of the bulk medium. We find that the bulk medium can stabilize configurations of the cluster that are usually not observed in the gas phase, while also simultaneously lowering the excess chemical potential of the ion. This effect is more pronounced for soft ions. Since the coordination number that minimizes the excess chemical potential of the ion is identified as the optimal or most probable coordination number, for such soft ions the optimum cluster size and the hydration thermodynamics obtained with and without account of the bulk medium on the ion-water clustering reaction can be different. The ideas presented in this work are expected to be relevant to experimental studies that translate thermochemistry of ion-water clusters to the thermodynamics of the hydrated ion and to evolving theoretical approaches that combine high-level calculations on clusters with coarse-grained models of the medium.