The influence of monovalent cations on the stability of electrochemically formed nickel fluoride films

The stability of electrochemically formed NiF₂ film in 1.0 M perchloric acid containing monovalent fluorides namely, NH₄F, HF, NaF, KF and LiF, is investigated using cyclic voltammetry, chronoamperometry, atomic absorption spectroscopy and scanning electron microscopy. In addition to direct dissolution of nickel and dissolution through the oxide layer, a new mode of dissolution of NiF₂ film as NiF₃ ⁻ and NiF₄ ²⁻ through complex formation is proposed. This process is significantly influenced by the alkali metal fluorides. On a comparative basis the stability of NiF₂ decreases in the order NH₄F > HF > KF > LiF. Received: 29 July 1998 / Accepted: 3 November 1998     

White graphene reinforced polypyrrole and poly(vinyl alcohol) blend nanocomposites as chemiresistive sensors for room temperature detection of liquid petroleum gases

Microchimica Acta - The authors describe the preparation of PVA/WPPy/hBNNP nanocomposite films by solution casting method from poly(vinyl alcohol) (PVA), water soluble polypyrrole (WPPy), and using...     

Double Schiff bases derivatives of chitosan by selective C-6 and C-2 oxidation mediated by 5-fluorosalicylaldehyde aniline by TG-GC-MS and TG-FTIR analysis

Abstract

This enhancement in the activity may be efficient on the basis that ligands mainly possess CH=N bond. The use of a structure-based drug design approach (SBDD) provides a way for investigation as well as to understand the molecular basis of the target protein and ligand molecule interactions at the atomic level. Structure-based drug design is the design and optimization of a chemical structure to identify a compound suitable for clinical testing the drug candidates. Chitosan is a polysaccharide with recognized biological activities for improving the functionality of polysaccharide 5-Fluorosalicylaldehyde aniline system. The used for selectively oxidized chitosan to produce tailored derivatives. C-2-5-Fluorosalicylaldehyde-C-6 aniline double Schiff base derivatives of chitosan were synthesized. The structure and properties of the newly synthesized product were characterized by FT-IR, ¹H-NMR, ¹³C-NMR, GC-Mass spectroscopy, and thermal analysis (DSC/TGA). An exothermic process discusses a DSC and TGA analysis of thermal behavior of this polymer was shown to be a possible thermal polymerization of the double bonds in the polymer chains and thermo-oxidation of the polymer.     

Spatial and temporal variations of radon concentrations in groundwater of hard rock aquifers in Madurai district,India

Radon (²²²Rn) and other radionuclides in groundwater can lead to health problems if present in higher concentrations. A study was carried out in Madurai district of Tamilnadu by collecting groundwater samples for four different seasons and aims to identify the regions with higher ²²²Rn concentration along with their spatial and seasonal variations. ²²²Rn has been compared with field parameters, log pCO₂, major ions and uranium to detect the factors responsible for the higher concentration in groundwater. The weathering process induces the release of higher uranium ions from the granitic terrain from the rock matrix which enhances the ²²²Rn levels in groundwater.     

Umbilical projection

Proceedings - Mathematical Sciences -     

A study of the thermal properties of single jersey fabrics of cotton, bamboo and cotton/bamboo blended-yarn vis-a-vis bamboo fibre presence and yarn count

In this study, the thermal properties of 100% cotton, 50/50 cotton/bamboo and 100% bamboo single jersey fabrics with differing yarn linear density are evaluated and analysed. The linear densities of the yarns composing the fabrics are 20^s, 25^s, 30^s Ne_c and the twist level in the yarns is kept the same. An increasing the presence of bamboo fibre in the fabric causes a reduction in fabric thickness and GSM for all linear densities of yarn. Air permeability and water-vapour permeability also increase with increase in bamboo fibre content while both thermal conductivity and thermal resistance show a decreasing trend. As the constituent yarn gets finer, fabric air and water-vapour permeability both increase in value while the thermal conductivity falls.     

Ruthenium catalyzed hydroboration of terminal alkynes to z-vinylboronates

The nonclassical ruthenium hydride pincer complex [Ru(PNP)(H)(2)(H(2))] 1 (PNP = 1,3-bis(di-tert-butyl-phosphinomethyl)pyridine) catalyzes the anti-Markovnikov addition of pinacolborane to terminal alkynes yielding Z-vinylboronates at mild conditions. The complex [Ru(PNP)(H)(2)(HBpin)] 2 (HBpin = pinacolborane), which was identified at the end of the reaction and prepared independently, is proposed as the direct precursor to the catalytic cycle involving rearrangement of coordinated alkyne to Z-vinylidene as a key step for the apparent trans-hydroboration.     

Regioselective synthesis of mono- and bis-decahydrobenzocarbazoles via tandem reactions of α-diazo ketones

Regioselective intermolecular 1,3-dipolar cycloaddition reactions of rhodium generated carbonyl ylides with indoles are reported in this paper. Intermolecular 1,3-dipolar cycloaddition reactions of five-membered-ring cyclic carbonyl ylides with indole and substituted indoles afforded hexahydro-2H-carbazol-2-ones in a regioselective manner. Similarly, reactions of cyclic carbonyl ylides were carried out to afford decahydrobenzo[c]carbazoles or decahydrocyclopenta[c]carbazoles with high regioselectivity. Interestingly, the other possible regioisomer decahydrobenzo[a]carbazoles were also obtained by the reaction of cyclic carbonyl ylides and indoles having electron withdrawing substituents. The structure and stereochemistry of regioisomers 6,11c-epoxy-1,2,3,4,4a,5,6,6a,11b,11c-decahydro-4a-methyl-5-oxo-7H-benzo[c]carbazole and 11-benzenesulfonyl-6,11b-epoxy-2,3,4,4a,5,6,6a,11,11a,11b-decahydro-4a-methyl-5-oxo-1H-benzo[a]carbazole were unequivocally corroborated by single-crystal X-ray analyses. To advance this study, regioselective double 1,3-dipolar cycloaddition reaction of five-membered-ring cyclic carbonyl ylides has been demonstrated for the first time with biindoles having various aryl and alkyl spacers. This process constructed up to eight stereocenters, four carbon-carbon and two carbon-oxygen bonds in a single step with an excellent molecular complexity and stereoselectivity.