Some inhomogeneous magnetized viscous-fluid cosmological models with varyingΛ

Some cylindrically symmetric inhomogeneous viscous-fluid cosmological models with electromagnetic field are obtained. To get a solution a supplementary condition between metric potentials is used. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. Without assuming anyad hoc law, we obtain a cosmological constant as a decreasing function of time. The behaviour of the electromagnetic field tensor together with some physical aspects of the model are also discussed.     

Supramolecular peptide helix from a novel double turn forming peptide containing a β-amino acid

A single-crystal X-ray diffraction study of the terminally protected tetrapeptide Boc-β-Ala-Aib-Leu-Aib-OMe 1 (Aib: α-aminoisobutyric acid; β-Ala: β-Alanine) reveals that it adopts a new type of double turn structure which self-associates to form a unique supramolecular helix through intermolecular hydrogen bonds. Scanning electron microscopic studies show that peptide 1 exhibits amyloid-like fibrillar morphology in the solid state.     

Synthesis and DNA binding properties of pyrrole amino acid-containing peptides

Dimers of the pyrrole amino acid (Paa), 5-(aminomethyl)pyrrole-2-carboxylic acid, and its derivatives having Lys anchored on N- and C-termini bind in the minor groove of DNA with considerable apparent binding affinities. When the Lys unit is attached to the C-terminus, the resulting ligand binds to ds-DNA with twice the affinity, of the order of 10⁵, than the one carrying two positive charges at the same end.     

Partitioning of quencher ions in the micellar microenvironment of polyoxyethylene nonyl phenol

This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu2+, Co2+, Ni2+ and Mn2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal.     

Simultaneous determination of copper,mercury and antimony in biological samples by neutron activation and substoichiometric extraction

A simple and accurate method has been developed for the determination of copper, mercury and antimony by thermal neutron activation analysis involving substoichiometric extraction technique. The results of analysis indicate that copper, mercury and antimony in biological samples can be determined with an accuracy of 5.3%, 5.5% and 6.2%, respectively. Two samples and a standard can be analysed by the proposed method in about 4 hrs. Part of this work was presented at the International Conference on Modern Trends in Activation Analysis, Saclay, Paris, France, October 2–6, 1972.     

Synthesis and characterization of Boc-protected 4-amino- and 5-amino-pyrrole-2-carboxylic acid methyl esters

Syntheses of Boc-protected 4-amino- and 5-amino-pyrrole-2-carboxylic acid methyl esters have been achieved and the structures of these compounds have been fully characterized by detailed NMR studies.     

Application of directed metalation in synthesis. Part 7: Synthesis of suitably functionalised benzo[b]thiophenes as key intermediates in the synthesis of benzothienopyranones

One-pot syntheses of (3-hydroxybenzo[b]thiophen-2-yl) aryl methanones from ortho-methylsulfanylaryl N,N-diethyl amides and of 1-(3-hydroxybenzo[b]thiophen-2-yl)ethanone and 1-(3-hydroxybenzo[b]thiophen-2-yl)propan-1-one via an anionic ortho-Fries rearrangement are described. The hydroxy ketones were used as key intermediates in the synthesis of benzothienopyranones.     

Highly efficient water promoted allylation and propargylation of arylepoxides via rearrangement-carbonyl addition

A simple and highly efficient one-pot procedure for allylation and propargylation of arylepoxides has been developed. A combination of SnCl₂ and catalytic Pd(0) or Pd(II) promotes the reaction of organic halides and epoxides in DMSO with controlled water addition, leading to the regioselective formation of the corresponding homoallyl and homopropargyl alcohols in good yields.     

Constrained photophysics of 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine in micellar environments: a spectrofluorometric study

Photophysical properties of 3-acetyl-4-oxo-6,7-dihydro-12H indolo-[2,3-a] quinolizine (AODIQ) have been studied in different aqueous micellar environments using steady-state and time-resolved emission spectroscopy. The charge transfer (CT) fluorescence exhibits appreciable hypsochromic shift, along with an enhancement in the fluorescence intensity in all the micellar media. This is associated with an increase in the fluorescence anisotropy (r), which suggests that the fluorophore molecule experiences motionally restricted environments upon binding with the micelles. Fluorescence spectral position and fluorescence quenching studies suggest that the fluorescing moiety does not penetrate into the core of the micellar units; rather it binds at the micelle-water interfacial region. The binding constant and free energy change during probe-micelle binding have been evaluated from relevant fluorescence data. Light has been thrown on the mode of action of urea on micelle bound probes. The results are interpreted in terms of the model that urea displaces water molecules from the micellar interface and the consequent destabilization leads to the expulsion of the probe molecules from the interfacial region. Polarity and viscosity of the microenvironments around the probe have been determined in the micellar systems.