Search

[70]fullerene solutions in carbon tetrachloride and o-xylene exhibit a noteworthy spectral variation with time when acetonitrile is added. This has been ascribed to self-aggregation of [70]fullerene caused by the repulsion between polar acetonitrile and hydrophobic [70]fullerene, and the aggregation numbers have been determined from a kinetic scheme and also from a scanning electron microscopic study. The numbers thus obtained follow a cuboctahedral stacking pattern proposed recently and also agree with the magic formula n=55+3m (m=1 to 14) proposed by Branz et al. for [60]fullerene clusters [Phys. Rev. B. 66, 094107 (2002)]. [ABSTRACT FROM AUTHOR]

Change-transfer absorption bands of the host-guest complexes of [60]- and [70]- fullerenes with the aza crown ether N,N'-dibenzyl-1,4,10,13-tetraoxa-7,16-diaza-cyclooctadecane in pi-donor solvents and also in the nondonor solvent is detected. The CT absorption band of the [70]- fullerene-aza crown complex appears at a longer wavelength than that of the fullerene complex in each solvent.

The limitations of CMOS technology led to the discoveries of new technologies, one of which is quantum-dot cellular automata. This upcoming technology is making its way because of high efficiency, high speed and small space requirement. Two-dot one-electron cells are used to design a parity generator and checker. Parity generator and checker aids in flawless binary data transmission from the source to the destination. Both irreversible as well as reversible parity generators and checkers are designed. It is seen that the amount of energy and power needed to drive these architectures is very low. [ABSTRACT FROM AUTHOR]

Abstract: Charge transfer complexes of 1:1 stoichiometry have been found to form between vitamin B6 (pyridoxine hydrochloride) and a series of electron acceptors including p-chloranil. Since vitamin B6 is soluble in water while the electron acceptors are insoluble in water but soluble in ethanol, the medium chosen for study is water–ethanol mixture. From the trends in the CT absorption bands the vertical ionization potential of vitamin B6 has been determined to be 8.12eV. The enthalpy and entropy of formation of the complex between p-chloranil and vitamin B6 have been determined by estimating the formation constant (K) spectroscopically at four different temperatures in 75% ethanol–water mixture. Again, the magnitude of K has been found to decrease noticeably with decrease in dielectric constant of the medium (as the percentage of ethanol in the aqueous–ethanol mixture is increased). A plausible explanation for this has been given in terms of hydrolysis of pyridoxine hydrochloride. [Copyright &y& Elsevier]

Six octapeptide bombesin (BN) analogs were synthesized by substituting α-aminoisobutyric acid (Aib), in place of Ala9 or Gly11, or both, in the [D-Phe6, desMet14]-BN (6-14) sequence: D-Phe6-Gln7-Trp8-Ala9-Val10-Gly11-His12-Leu13-NH2 ( P0). Additionally, Leu13 was replaced with isoleucine in two analogs and one of the analogs was butanoylated at the N-terminus. The antiproliferative activity of the analogs was tested in vitro on human pancreatic (MiaPaCa-2) and colon cancer (SW620, HT29 and PTC) cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The analogs demonstrated anticancer activity in the above cell lines at concentrations ranging from 0.01 n M to 1 µ M. One of the analogs, P6, was evaluated for in vivo tumor regression in a xenograft model of human primary colon cancer in athymic nude mice and was found to cause significant reduction in tumor volume. NMR and molecular dynamics (MD) simulation studies for this analog revealed the presence of a mixed 310/α-helical structure. This study demonstrates that the designed BN analogs retain their anticancer activity after the incorporation of the constrained amino acid, Aib, and are potential molecules for future use in cancer therapy and drug targeting. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]