PREFERENTIAL INHIBITION OF NUCLEOSOME ASSEMBLY BY ULTRAVIOLET-INDUCED (6-4)PHOTOPRODUCTS

We reconstituted nucleosomes in vitro using two kinds of damaged pBR322 plasmid DNA carrying cyclobutane pyrimidine dimers (CPD) or (6-4)photoproducts. The results indicate that nucleosome assembly is inhibited preferentially by (6-4)photoproducts compared with CPD, suggesting that the regions carrying (6-4)photoproducts retain their nucleosome-free form, i.e. linker-like conformation until completion of the repair processes.     

Commutativity of association schemes of prime square order having non-trivial thin closed subsets

Through a study of the structure of the modular adjacency algebra over a field of positive characteristic p for a scheme of prime order p and utilizing the fact that every scheme of prime order is commutative, we show that every association scheme of prime square order having a non-trivial thin closed subset is commutative. The second author was supported by Korea Research Foundation Grant (KRF-2006-003-00008).     

On p-covalenced association schemes

Let (X,S) denote an association scheme where X is a finite set. For a prime p we say that (X,S) is p-covalenced (p-valenced) if every multiplicity (valency, respectively) of (X,S) is a power of p. In the character theory of finite groups Ito's theorem states that a finite group G has a normal abelian p-complement if and only if every character degree of G is a power of p. In this article we generalize Ito's theorem to p-valenced association schemes, i.e., a p-valenced association scheme (X,S) has a normal p-covalenced p-complement if and only if (X,S) is p-covalenced.     

Ionic conductivities of Nasicon-type glass-ceramic superionic conductors in the system Na2O–Y2O3–XO2–SiO2 (X = Ti,Ge, Te)

Glass-ceramics of the titanium-, germanium- or tellurium-containing Na₅RSi₄O₁₂-type (R = rare earth; Y) Na⁺-superionic conductors (N5YXS) were prepared by crystallization of glasses with the composition Na_3+3xY_1 ? xX_ySi_3 ? yO₉ (X = Ti; NYTiS, Ge; NYGeS, X = Te; NYTeS), and the effects of X elements on the separation of the phase and the microstructural effects on the conduction properties of glass-ceramics were discussed. The combination of x and y was most varied in N5YGeS and more limited in the order of N5YTeS > N5YTiS. Their conductivities and activation energies are of the order of 10^? 2 S/cm at 300 °C and of 15 to 24 kJ/mol, respectively. The conductivity of the glass-ceramic N5YXS decreases giving the order N5YGeS > N5YTeS > N5YTiS. It is considered that this order corresponds to the N5 single phase region. Large enhancement of electrical conductivity was observed in the glass-ceramics as the grain growth was promoted with increase of heating temperature and heating time for crystallization.     

Experimental and Numerical Analysis of Thermal Deformation of Electronic Packages,QFP and MCM

0Introduction Anelectronicpackageisgenerallyconstructedwithanactivesiliconchip,mountisland,gold wires,leadframesandsoldersasshowninFig.1(a).Toprotectfromtheenvironment,thesilicon chipisusuallyencapsulatedinresin.SincethesematerialshavedifferentCTE(coefficientofthermal expansion),stressandstrainaregeneratedbyinternalheatinginserviceoperationorthermalloading fromtheenvironment[1].Insomecases,thismaycausefailureofthewireandcrackinganddebonding insidethepackage.Thereliabilityofelectronicpackages…     

Effect of PEO‐PPO‐PEO copolymer on the mechanical and thermal properties and morphological behavior of biodegradable poly (L‐lactic acid) (PLLA) and poly (butylene succinate‐co‐L‐lactate) (PBSL) blends

A blend of two biodegradable and semi‐crystalline polymers, poly (L‐lactic acid) (PLLA; 70 wt%) and poly (butylene succinate‐co‐L‐lactate) (PBSL; 30 wt%), was prepared in the presence of various polyethylene oxide‐polypropylene oxide‐polyethylene oxide (PEO‐PPO‐PEO) triblock copolymer contents (0.5, 1, 2 wt%). Mechanical, thermal properties, and Fourier transform infrared (FTIR) analysis of the blends were investigated. It was found that the addition of copolymer to PLLA/PBSL improved the fracture toughness of the blends as shown by mode I fracture energies. It was supported by morphological analysis where the brittle deformation behavior of PLLA changed to ductile deformation with the presence of elongated fibril structure in the blend with copolymer system. The glass transition temperature (T_g), melting temperature (T_m) of PLLA, and PBSL shift‐closed together indicated that some compatibility exists in the blends. In short, PEO‐PPO‐PEO could be used as compatibilizer to improve the toughness and compatibility of the PLLA/PBSL blends. Copyright © 2010 John Wiley & Sons, Ltd.