Reductive nitrosylation of tetraoxometallates—XI. Molybdate hydroxylamine reaction in the presence of cyanide: Synthesis of mono- and dinitrosyl cyan

The new molybdenum cyanonitrosyl complexes, R₂[Mo(NO)(CN)₅]·2H₂O (R = Ph₄P and Bu₄N) and [Mo(NO)(CN)₃(L-L)]·H₂O [L-L =     

On circular designs

Summary A general method of analysis of circular designs (Das [3]) is suggested. Average efficiency factors of these designs have been tabulated.A-optimality of circular designs has been studied in comparison to group divisible incomplete block designs.     

An extended Hückel study of hydrogen and oxygen chemisorption on Ru(001) surface

Extended Hückel MO theory has been applied to treat the chemisorption of hydrogen and oxygen atoms on Ru(001) surfaces. The site of chemisorption, surface-adatom distance, chemisorption energy and the vibrational frequency of the adatom on the surface have been calculated. For different sites, the chemisorption energy (E_c) results are as follows: For hydrogen, |E_c|(centre) > |E_c|(top) > |E_c|(bridge); while for oxygen, |E_c|(bridge) > |E_c|(top) > |E_c|(centre). These results are critically discussed in the light of the recent results obtained from the electron energy-loss spectroscopy (EELS) experiments.     

Role of dopant concentration and surface coating on photophysical properties of CdS: Eu3+ nanocrystals

Here, we report the role of dopant concentration and surface coating of CdS: Eu3+ nanocrystals on the modification of crystal structure and their photoluminescence properties by steady-state and time resolved fluorescence studies. It is found that photoluminescence properties are sensitive to the crystal structure which is controlled by surface coating and dopant concentration. The emission intensity of the peak at 614 nm (5D0 --> 7F2) of the Eu3+-ions is found to be sensitive to the doping and surface coating of CdS nanocrystals. It is found that the average decay times tau are 248, 353 and 499 micros for 0.25, 0.5 and 1.0 mol% Eu ions doped into CdS nanocrystals, respectively. From the decay time measurements, it is evident that the energy transfer occurs from CdS nanoparticles to Eu3+ ions and the calculated energy transfer efficiency from CdS nanoparticles to Eu3+ ions is 9.2 and 35% for Eu3+ ions coated and doped CdS nanoparticles, respectively. Our analysis suggests that site symmetry of ions plays a very important role in the modifications of radiative and nonradiative relaxation mechanisms.     

Spectroscopic and thermodynamic study of charge transfer complex formation between cloxacillin sodium and riboflavin in aqueous ethanol media of varying composition

Cloxacillin sodium has been shown to form a charge transfer complex of 2:1 stoichiometry with riboflavin (Vitamin B(2)) in aqueous ethanol medium. The enthalpy and entropy of formation of this complex have been determined by estimating the formation constant spectrophotometrically at five different temperatures in pure water medium. Pronounced effect of dielectric constant of the medium on the magnitude of K has been observed by determining K in aqueous ethanol mixtures of varying composition. This has been rationalized in terms of ionic dissociation of the cloxacillin sodium (D(-)Na(+)), hydrolysis of the anion D(-) and complexation of the free acid, DH with riboflavin.     

First example of an ice-like water hexamer boat tape structure in a supramolecular organic host

A T6(2) tape of hydrogen bonded water molecules in boat cyclohexane conformation resides in the channel structure of a dibromophloroglucinol (DBPG) host; water escapes at 40-90 degrees C but is readily re-absorbed by the sponge-like apohost.     

Nucleation efficiency of R134a as a sensitive liquid for superheated drop emulsion detector

Superheated emulsion detector is known to detect neutrons, γ-rays and other charged particles. The present work includes the study of nucleation efficiency of superheated drops of one of the CFC-free liquids, R134a (C₂H₂F₄), to fast neutrons, its response to γ-rays from ²⁴¹Am and ¹³⁷Cs and compare its nucleation efficiency with that of R12. The observation indicates that because of the presence of hydrogen, the nucleation efficiency is less in R134a than in R12 in the present neutron energy range of consideration. R134a is one of the most environment-friendly, commercially available liquid that is suitable for superheated drop detector, specially in neutron dosimetry and one needs to investigate it in detail.     

Optical and electrical properties of p-type transparent conducting CuAlO2 thin film synthesized by reactive radio frequency magnetron sputtering technique

Thin films of p-type transparent conducting CuAlO₂ have been synthesized through reactive radio frequency magnetron sputtering on silicon and glass substrates at substrate temperature 300°C. Reactive sputtering of a target fabricated from Cu and Al powder (1:1.5) was performed in Ar+O₂ atmosphere. The deposition parameters were optimized to obtain phase pure, good quality CuAlO₂ thin films. The films were characterized by studying their structural, morphological, optical and electrical properties.