Continuous wave NMR of submonolayer 3He adsorbed on grafoil

NMR linewidths and magnetic susceptibilities of ³He adsorbed on Grafoil have been measured by a continuous wave technique between 0.40 K to 4.21 K for five fractional monolayer coverages, x, between 0.20 and 0.96. Interpretations in terms of the phases of the submonolayers are presented.     

A Facile One‐Pot Synthesis of Pyrrolo[1, 2‐a] Indoles by Intramolecular 1,3‐Dipolar Cycloaddition under Neat‐Microwave Irradiation

A straightforward and general approach for the stereoselective synthesis of fused pyrrolo[1,2‐a] indoles frameworks from>intramolecular 1,3‐dipolar cycloaddition using N‐alkylated Baylis–Hillman derivatives is presented. It was found that the cycloaddition proceeded efficiently under microwave irradiation in solvent‐free condition to afford highly stereoselective cycloadducts in good yield.     

Sonochemical synthesis of Ce(1-x)Fe(x)O(2-δ) (0 ≤ x ≤ 0.45) and Ce(0.65)Fe(0.33)Pd(0.02)O(2-δ) nanocrystallites: oxygen storage material, CO oxidation and water gas shift catalyst

Nanocrystalline Ce(1-x)Fe(x)O(2-δ) (0 ≤ x ≤ 0.45) and Ce(0.65)Fe(0.33)Pd(0.02)O(2-δ) of ~4 nm sizes were synthesized by a sonochemical method using diethyletriamine (DETA) as a complexing agent. Compounds were characterized by powder X-ray diffraction (XRD), X-ray photo-electron spectroscopy (XPS) and transmission electron microscopy (TEM). Ce(1-x)Fe(x)O(2-δ) (0 ≤ x ≤ 0.45) and Ce(0.65)Fe(0.33)Pd(0.02)O(2-δ) crystallize in fluorite structure where Fe is in +3, Ce is in +4 and Pd is in +2 oxidation state. Due to substitution of smaller Fe(3+) ion in CeO(2), lattice oxygen is activated and 33% Fe substituted CeO(2)i.e. Ce(0.67)Fe(0.33)O(1.835) reversibly releases 0.31[O] up to 600 °C which is higher or comparable to the oxygen storage capacity of CeO(2)-ZrO(2) based solid solutions (Catal. Today 2002, 74, 225-234). Due to interaction of redox potentials of Pd(2+/0)(0.89 V) and Fe(3+/2+) (0.77 V) with Ce(4+/3+) (1.61 V), Pd ion accelerates the electron transfer from Fe(2+) to Ce(4+) in Ce(0.65)Fe(0.33)Pd(0.02)O(1.815), making it a high oxygen storage material as well as a highly active catalyst for CO oxidation and water gas shift reaction. The activation energy for CO oxidation with Ce(0.65)Fe(0.33)Pd(0.02)O(1.815) is found to be as low as 38 kJ mol(-1). Ce(0.67)Fe(0.33)O(1.835) and Ce(0.65)Fe(0.33)Pd(0.02)O(1.815) have also shown high activity for the water gas shift reaction. CO conversion to CO(2) is 100% H(2) specific with these catalysts and conversion rate was found to be as high 27.2 μmoles g(-1) s(-1) and the activation energy was found to be 46.4 kJ mol(-1) for Ce(0.65)Fe(0.33)Pd(0.02)O(1.815).     

Electrodeposition and characterization Zn-Co alloy

The present work details optimization of a stable acid chloride bath for electroplating of bright Zn-Co alloy on mild steel using gelatin and glycine as additives. It was found that the addition of gelatin along with glycine changed the deposition pattern markedly. A suitable bath has been formulated using conventional Hull cell experiments. The bath under plating conditions were found to exhibit anomalous codeposition with preferential deposition of less noble (zinc) over more noble (cobalt) as characterized by Zn-Fe group metal alloys. Investigation revealed that the current density (c.d.), temperature, and pH of the bath have strong effect on the composition of the deposit. Influence of bath constituents and operating parameters on appearance and composition of deposits were studied as measure of their performance against corrosion. A variety of deposits were obtained and their corrosion resistances were measured by Tafel method with/without chrome passivation. Experimental results demonstrated the fact that the corrosion resistances of Zn-Co alloys increased with percent of Co in the deposit except at very high c.d. This is due to the fact at very high c.d. the deposit becomes very porous and thick as evidenced by SEM image. The formation of Zn-Co alloy is confirmed by EDAX analysis. A stable chloride bath for Zn-Co alloy deposition has been proposed and discussed. The formation of passive film on chromatization is indicated by almost same E _corr value of all Zn-Co electroplates irrespective of the current densities at which they have been deposited. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 811–816. The text is published in the original.     

Oxidative degradation and deamination of atenolol by diperiodatocuprate(III) in aqueous alkaline medium: A mechanistic study

The kinetics of oxidation of atenolol (ATN) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm⁻³ was studied spectrophotometrically. The reaction between DPC and ATN in alkaline medium exhibits 1:2 stoichiometry (ATN:DPC). The reaction is of first order in [DPC] and has less than unit order in both [ATN] and [alkali]. However, the order in [ATN] and [alkali] changes from first order to zero order as their concentration increase. Intervention of free radicals was observed in the reaction. Increase in periodate concentration decreases the rate. The oxidation reaction in alkaline medium has been shown to proceed via a monoperiodatocuprate(III)–ATN complex, which decomposes slowly in a rate-determining step followed by other fast steps to give the products. The main oxidative products were identified by spot test, IR, NMR and LC–ESI-MS studies. The reaction constants involved in the different steps of the mechanism are calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed, and thermodynamic quantities are also determined.     

Voltammetric oxidation and determination of cinnarizine at glassy carbon electrode modified with multi-walled carbon nanotubes

We discovered a novel method to prepare a protein-based hydrogel, that is, a “Three-Dimensional Nanostructured Protein Hydrogel (3D NPH)”, which is composed of protein–polymer hybrid nanoparticles. In this study, we propose a novel protein microarray whose 3D NPH spots were prepared by dispensing a small volume of the solution of protein–polymer mixture on a substrate. The dispensed solution had a short time for cross-linking before its drying-up and the resulting 3D NPH had loosely cross-linked, thin spongy structure. Therefore, the reaction ratio between ligands and analytes was drastically improved in this system compared with the large volume system for Surface Plasmon Resonance (SPR) protein microarray.     

Total synthesis of (-)-laulimalide

(-)-Laulimalide (1), a structurally novel macrolide isolated in trace amounts from marine sponges, promotes abnormal tubulin polymerization and apoptosis in vitro, with a similar mode of action to that of Taxol(R), but with potentially less susceptibility to multidrug resistance. Herein, a flexible and convergent asymmetric synthesis of (-)-laulimalide is described. This synthesis featured a highly diastereoselective Sakurai reaction of 2 with 3 and a regioselective macrolactonization of an unprotected vicinal diol. Laulimalide was synthesized in 25 steps (longest linear; 36 overall) in 3.5% overall yield, providing a uniquely short and efficient route to 1 and its analogues.     

Synthesis and structure of nanocrystalline TiO2 with lower band gap showing high photocatalytic activity

Nanocrystalline TiO2 was synthesized by the solution combustion method using titanyl nitrate and various fuels such as glycine, hexamethylenetetramine, and oxalyldihydrazide. These catalysts are active under visible light, have optical absorption wavelengths below 600 nm, and show superior photocatalytic activity for the degradation of methylene blue and phenol under UV and solar conditions compared to commercial TiO2, Degussa P-25. The higher photocatalytic activity is attributed to the structure of the catalyst. Various studies such as X-ray diffraction, Raman spectroscopy, Brunauer-Emmett-Teller surface area, thermogravimetric-differential thermal analysis, FT-IR spectroscopy, NMR, UV-vis spectroscopy, and surface acidity measurements were conducted. It was concluded that the primary factor for the enhanced activity of combustion-synthesized catalyst is a larger amount of surface hydroxyl groups and a lowered band gap. The lower band gap can be attributed to the carbon inclusion into the TiO2 giving TiO(2-2x)C(x) VO2**.     

Determination of thorium concentrations in soil and sand samples using instrumental neutron activation analysis

Thorium along with its daughter products present in the soil is one of the major contributors to the external gamma dose in the environment. To establish the dose levels, quantification of thorium contents in soil samples is very important. As a part of pre-operational environmental radiological surveillance, a total of 23 soil and six sand samples were collected from different locations around the proposed nuclear power plant site of Jaitapur, Maharashtra. Thorium concentrations in these samples were determined by instrumental neutron activation analysis (INAA). Samples were irradiated with neutrons in Apsara reactor at a neutron flux of?~5?×?10¹¹ cm^?2 s^?1 and radioactive assay was carried out using high resolution gamma ray spectrometry. Relative method of INAA was used for quantification of thorium utilizing 311.9?keV gamma ray of ²³³Pa, the daughter product of ²³³Th. The concentrations of thorium in the soil and sand samples were in the ranges of 4.0?C18.8 and 1.2?C6.2?mg?kg^?1 respectively.     

Separation of uranium from iron in ground water samples using ion exchange resins

Uranium determination in environmental samples is faced with problems due to presence of iron and other major elements. Iron is also used many a times for pre-concentration of uranium and actinides. Separation of milligram quantity of Fe from microgram quantity of uranium becomes essential during the estimation step. A simple two step procedure has been standardized for separating uranium and iron using anion exchange in 0.025 M H₂SO₄. Quantitative recovery of uranium was obtained as well as good separation from iron. This method was applied for estimation of uranium in water samples.