Bound D‐states of helium atom under Debye screening

We have investigated the 1snd^1,3D (3 ≤ n ≤ 7) state energies of helium atom embedded in weakly coupled plasma environments using the Rayleigh–Ritz variational method. The effect of the plasma environment is taken care of using a Debye screening model. A correlated wave function involving exponential expansion has been used to represent correlation between the charge particles. The bound 1snd^1,3D (3 ≤ n ≤ 7) state energies of helium for various Debye lengths along with the excitation energies of few singlet and triplet states are reported. Our results are useful references to atomic physics, plasma physics, and astrophysics research communities. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Chemical and radiochemical separation of strontium and yttrium

Summary A procedure is presented for the chemical and radiochemioal separation of strontium and yttrium in mixtures which is based on the selective carrying of strontium by ignited barium sulphate leaving yttrium in the solution phase; the carried strontium is recovered by leaching with aqueous hydrochloric acid solution. In order to make strontium radiochemically free from yttrium activity, an initial isotopic dilution of the latter with 1 mg of inactive yttrium is an essential requirement. The method is applicable to chemical analysis of mixtures involving 1 to 3 mg of strontium and 1 to 16 mg of yttrium, both components being determined complexometrically after separation.

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Zusammenfassung Ein Verfahren zur chemischen und radioehemischen Trennung von Strontium und Yttrium in Gemischen wurde vorgeschlagen, das auf der selektiven Abscheidung von Sr mit geglühtem Bariumsulfat beruht, wobei Y in der Lösung zurückbleibt; Sr wird dann mit wäßriger Salzsäure ausgewaschen. Um jede radiochemische Y-Aktivität aus dem Sr zu entfernen, ist es wesentlich, vorher mit 1 mg Y-Isotop zu verdünnen. Das Verfahren ist für die chemische Analyse von Gemischen aus 1 bis 3 mg Sr und 1 bis 16 mg Y verwendbar. Die beiden Komponenten werden nach der Trennung komplexometrisch bestimmt.

     

Optical and magnetic properties of manganese-incorporated zinc sulfide nanorods synthesized by a solvothermal process

Manganese-incorporated ZnS (MnxZn1-xS) nanorods were synthesized by a simple solvothermal process. Synthesized nanorods were single crystalline. Manganese incorporation in the ZnS lattice induces a phase transformation from hexagonal wurtzite to cubic zinc blende structure. The diameter of the nanorods increased with the increase of Mn concentration. Intense orange luminescence at approximately 585 nm was observed for the nanorods. Six-line hyperfine splitting was observed in the EPR spectra for lower Mn concentrations, whereas broad Lorentzian-shaped EPR spectra were obtained for higher Mn concentrations because of the Mn-Mn cluster formation at higher Mn concentrations.     

The status of trace and minor elements in pulses: A PIXE measurement

The proton particle induced X-ray emission (proton PIXE) technique has been employed to study the heavy element status (essential and toxic) in five different varieties of pulses commonly cultivated and consumed in Bangladesh. In this analysis, the samples were irradiated in air with 2 MeV protons having 30 nA beam intensity for characteristic X-ray excitation. For 40 μC irradiations, the concentration of ten elements (K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, and Rb) was determined by comparison with a calibration obtained from the NBS orchard leaf standard, SRM 1571. In a comparative study with atomic absorption spectrophotometric (AAS) measurements of some elements in lathyrus sativus, the data were found to be in good agreement. The results obtained from the present study are discussed and compared with available data.     

The study of the Cd(NH3) 4 2+ /Cd*(NH3) 4 2+ exchange reaction in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV)

Kinetics of the exchange reaction of cadmium(II)-ammine complex ion using radio-active isotope¹¹⁵Cd in the same chemical form in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV) has been studied. It has been found that the major contribution in the overall exchange process is from the surface of the exchanger particles. It has also been found that the rate of exchange follows the order: hydrous ZrO₂>hydrous SnO₂>hydrous SiO₂     

Studies on the synthesis of trans-dihydrodiols of polycyclic aromatic thiaarenes as potential proximate carcinogenic metabolites: first synthesis of trans-10,11-dihydroxy-10,11-dihydroacenaphtho[1, 2-b]benzo[d]thiophene and 6,7-dihydroxy-6,7-dihydronaphtho[1, 2-b]thiophene

Polyaromatic thiophene compounds are found to occur concomitantly with numerous coal-derived products and shale oils and are suspected mutagens and/or carcinogens. The first synthesis of the two title compounds 9 and 16 has been achieved in five or four steps starting from 8,9-dihydroacenaphtho[1,2-b]benzo[d]thiophene (1) and 7-methoxynaphtho[1,2-b]thiophene (12), respectively. Compound 1 was converted to the cis-diol (11) (via treatment with OsO(4)/pyridine) or to trans-diol (3) [via Prevost reaction (PhCOOAg/I(2)) followed by hydrolysis] in 95-98% yield, respectively. Subsequent dehydration (PTS/benzene) of the diol followed by aromatization of the resulting ketone (5) produced the phenolic compound 6 in 97% yield. Oxidation of the phenol with phenyl iododiacetate followed by hydrolysis of the o-quinone monoketal 7 gave the o-quinone (8) in 86% yield. Stereoselective reduction of 8 with NaBH(4)/EtOH under oxygen afforded trans-10,11-dihydroxy-10,11-dihydroacenaphtho[1,2-b]benzo[d]thi oph ene(9) (orange yellow solid) in 55% yield. Compound 16 was obtained as a colorless solid, through the stereoselective reduction of the o-quinone 15 (with NaBH(4)), which in turn was prepared from 12 following the protocol of functional group transformation of methoxy --> phenol --> o-quinone monoketal --> o-quinone, as used in the previous case. The yields for all the steps are very good. The mutagenicity assay of compound 9 and 16 as well as their parent thiaarenes have been performed. The results showed that 9 may not be the proximate carcinogen of acenaphtho[1,2-b]benzo[d]thiophene, while it is likely that compound 16 is one of the possible proximate carcinogens for naphtho[1,2-b]thiophene.     

UV-mediated DNA strand breaks in corneal epithelial cells assessed using the comet assay procedure

Ultraviolet (UV)-mediated DNA damage in various tissues has been well documented. However, research on the damaging effect of UV irradiation on the DNA of corneal epithelium is scarce, even though this is of interest because the cornea is directly exposed to damaging solar (UV) radiation. In this study, we developed a corneal epithelium Comet assay model to assess the background DNA damage (as strand breaks) in cells retrieved from different layers of the porcine corneal epithelium, and to investigate the effect of UV irradiation on DNA damage in corneal epithelial cells. Results show that the background DNA strand breaks decreased significantly (P < 0.001) toward deeper layers of the epithelium. Exposure to the same intensity (0.216 J/cm2) of UVA, UVB and UVC caused a significant (P < 0.001) increase in DNA strand breaks of deeper-layer cells: mean +/- SD %DNA scores (10 gels per treatment, with 100 irradiated cells scored per gel) were 10.2% +/- 1.4% for UVA, 27.4% +/- 4.6% for UVB, and 14.7% +/- 1.8% for UVC compared with 4.2% +/- 0.5% for controls (ambient room light). This study has shown for the first time that the Comet assay for DNA strand breaks can be used successfully with corneal epithelial cells. This report will support future studies investigating environmental influences on corneal health and the assessment of possible protective strategies, and in applying DNA lesion-specific versions of the Comet assay in this corneal epithelial cell model.     

Studies on polycyclic thiaarenes: Part II. An improved synthesis of phenanthro[1,2-b]thiophene and a synthesis of acenaphtho[1,2-b]naphtho-[2,3-d]thiophene,a novel polynuclear thiaarene

An improved synthesis of phenanthro[1,2-b]thiophene ( 6 ) from 1-chloro-3,4-dihydrophenanthrene-2-aldehyde ( 2 ) by condensation with thioglycolate followed by hydrolysis, decarboxylation and dehydrogenation is described. A new polycyclic thiophene derivative 14 has also been prepared from acenaphthothiophene ( 7 ) by Friedel-Craft's reaction with phthalic anhydride followed by lactonisation of the keto carboxylic acid 9 and then reduction and finally cyclisation of the resultant aldehyde 13 .     

Coupling reactions of CO2 with neat epoxides catalyzed by PPN salts to yield cyclic carbonates

The off-the-shelf reagent PPN+Cl- and PPN-manganese carbonylates [PPN]+[Mn(CO)4L]- (L = CO, PPh3) are good catalysts for the coupling reactions of CO2 with neat epoxides without the use of organic solvents to afford cyclic carbonates. PPN salts with weak nucleophilic anions such as PPN+BF4- and PPN+OTf- are, however, inactive for the coupling reactions.