Antioxidant and Prooxidant Effects of Metal Dafonates on the NADPH-Dependent Lipid Peroxidation in the Murine Hepatic Microsomal System

Dafone inhibits the lipid peroxidation significantly in a concentration dependent manner. The inhibition was found to be an uncompetitive type with the inhibition constant (Ki) of 62.5muM On the other hand complexation with metal ions results in a significant reversal from antioxidant to pro-oxidant properties for the resulting complexes which are cationic and with associated halometallate anions. The nature of the potentiation in case of the ferric compound was of competitive type with activation constant (Ka) having the value 32.5muM. The neutral copper-dafonate complex, however, inhibits lipid peroxidation with increase in concentration.     

Hydroxynaphthoquinone metal complexes as antitumor agents x: synthesis, structure, spectroscopy and in vitro antitumor activity of 3-methyl-phenylazo lawsone derivatives and their metal complexes against human breast cancer cell line mcf-7

The C-3 substituted phenylazo derivatives of lawsone (2-hydroxy-l,4 p-naphthoquinone, III) were synthesized and characterized. The X-ray crystal structure was determined for the ligand 3-(3'-methyl phenylazo) lawsone. The copper complexes of these derivatives were found to possess 1:2 metal stoichiometry and square planar geometries with intermolecular stackings, resulting in antiferromagnetic exchange interactions. The in vitro activity of all the synthesized compounds was examined against human breast cancer cell-line, MCF-7, which revealed enhanced activities for the metal complexes, the highest activity being observed for the copper compound of 3-(3'-methyl phenylazo) lawsone.     

Dye–polymer interaction in nylon 66

Absolute orientation factors of dye and the amorphous region of the polymer nylon 66 have been determined from the dichroism of the visible band and that of the characteristic amorphous infrared band of the polymer. It has been shown that the orientations show a linear relationship with unit slope irrespective of whether the film was stretched before dyeing (prestretched) or stretched after dyeing (poststretched). The relation is the same for reactive as well as nonreactive disperse dye. The effect of thermal treatment at constant length shows that the dichroism of the dye decreases whereas that of the polymer does not and that it is reversible. It is concluded that disperse reactive as well as nonreactive dyes have specific interaction sites with the polymer.     

Deuteration of cotton fibers. II. A novel method of deuteration-infrared study of cellulose in fiber form

A new technique enabling the use of cellulosic material in the fiber form during deuteration-infrared studies is reported. A minipress, modified to suit the new technique, is described. Since the material was studied in the fiber form, danger of fiber modification during film formation was avoided. Although the usual KBr pellet technique was utilized for scanning the spectra of the deuterated fibers, preparation of pellet as well as scanning were carried out under fully dry conditions, thus completely avoiding the rehydrogenation of deuterated fibers. The modified minipress containing the pellet forms an airtight assembly allowing repeat scans after any length of time without affecting the quality of the spectra of the deuterated sample.     

Deformation-induced bonding of polymer films below the glass transition temperature

Bonding between polymers through interdiffusion of macromolecules is a well-known mechanism of polymer adhesion. A new polymer bonding mechanism in the solid state, taking place at ambient temperatures well below the glass transition value (T_g), has been recently reported; in this mechanism, bulk plastic compression of polymer films held in contact led to adhesion over timescales of the order of a fraction of a second. In this study, we prepared various blends of plasticized polymer films with desirable ductility from amorphous and semicrystalline powders of hydroxypropyl methylcellulose and polyvinyl alcohol derivatives; then, we observed the bonding of these polymers at ambient temperatures, up to 80 K below T_g, purely through mechanical deformation. The deformation-induced bonding of the polymer films studied in this work led to interfacial fracture toughnesses in the range of 1.0–21.0 J/m² when bulk plastic strains between 3% and 30% were imposed across the films. Scanning electron microscopy observation of the debonded interfaces also confirmed that bonding was caused by deformation-induced macromolecular mobilization and interpenetration. These results expand the range of applicability of sub-T_g, solid-state, deformation-induced bonding processes.     

Hormone anchored metal complexes. 1. Synthesis, structure, spectroscopy and in vitro antitumor activity of testosterone acetate thiosemicarbazone and its metal complexes

Testosterone acetate thiosemicarbazone (TATSC, 17-beta-hydroxyandrost-4-one acetate thiosemicarbazone) was synthesized and characterized by single crystal X-ray structure determination. The copper and platinum complexes of this steroid derivative were synthesized and characterized by spectroscopy and electrochemiatry. The in vitro activity of these compounds against human breast cancer cell line MCF-7 was tested. The highest activity was found for the [Pt(TATSC)Cl(1)] followed by [Cu(TATSC)Cl(2)] and the ligand in compariosn with cisplatin.     

Efficient ID-based proxy multi-signature scheme secure in random oracle

Proxy signature schemes enable an entity to delegate its signing rights to any other party, called proxy signer. As a variant of proxy signature primitive, proxymultisignature allows a group of original signers to delegate their signing capabilities to a single proxy signer in such a way that the proxy signer can sign a message on behalf of the group of original signers. We propose a concrete ID-based proxy multi-signature scheme from bilinear pairings. The proposed scheme is existential unforgeable against adaptively chosen message and given ID-attack in random oracle model under the computational Diffie-Hellman (CDH) assumption. The fascinating property of new scheme is that the size of a proxy multi-signature is independent of the number of original signers. Furthermore the proposed scheme is simple and computationally more efficient than other ID-based proxy multisignature schemes.     

Provable secure proxy signature scheme without bilinear pairings

Proxy signature is an active research area in cryptography. A proxy signature scheme allows an entity to delegate his or her signing capability to another entity in such a way that the latter can sign messages on behalf of the former. Many proxy signature schemes using bilinear pairings have been proposed. But the relative computation cost of the pairing is more than 10 times of the scalar multiplication over elliptic curve group. In order to save the running time and the size of the signature, we propose a proxy signature scheme without bilinear pairings and prove its security against adaptive chosen‐message attack in random oracle model. The security of our scheme is based on the hardness of the elliptic curve discrete logarithm problem. With the running time being saved greatly, our scheme is more practical than the previous related scheme for practical applications. Copyright © 2011 John Wiley & Sons, Ltd.