Simultaneous imaging for surface and internal structure of polymer blend thin films

A novel experimental technique for three-dimensional (3D) visualization of phase-separated structure of polymer blend thin film was proposed. Polystyrene/poly(methyl methacrylate) (PS/PMMA) blend thin films with the thickness of approximately 100 nm were cut at extremely low angle by utilizing surface and interface cutting analysis system (SAICAS), and the cross-section was exposed as gradient surface with the width of approximately 2.5 μm. SFM investigation for the grazing cross-section imaged the detailed internal and surface phase separated structure of the (PS/PMMA) blend thin films on one image.     

Ethylaluminum oxide catalysts from Et2AlOLi–Et2AlCl binary system in relation to species of AlEt3–water catalyst

Equimolar reaction of Et₂AlOLi and Et₂AlCl gave Et₂AlOAlEt₂. The catalyst behavior for polymerization of acetaldehyde, propylene oxide, and epichlorohydrin was compared with that of the AlEt₃–H₂O (1:0.5) catalyst system. The thermal disproportionation product of Et₂AlOAlEt₂ derived from Et₂AlOLi–Et₂AlCl had the structure, ? (EtAlO)_n? , and it showed catalyst behavior quite similar to that of the product obtained by the same treatment of AlEt₃–H₂O (1:0.5). These ethylaluminum oxides can be regarded as species predominating in AlEt₃–H₂O (1:0.5) and AlEt₃–H₂O (1:1), respectively. Stereospecific or high molecular weight polymerizations of these species were investigated.     

Characterization of Radical SAM Adenosylhopane Synthase,HpnH, which Catalyzes the 5′-Deoxyadenosyl Radical Addition to Diploptene in the Biosynthesis of C35 Bacteriohopanepolyols

Adenosylhopane is a crucial intermediate in the biosynthesis of bacteriohopanepolyols, which are widespread prokaryotic membrane lipids. Herein, it is demonstrated that reconstituted HpnH, a putative radical S-adenosyl-l -methionine (SAM) enzyme, commonly encoded in the hopanoid biosynthetic gene cluster, converts diploptene into adenosylhopane in the presence of SAM, flavodoxin, flavodoxin reductase, and NADPH. NMR spectra of the enzymatic reaction product were identical to those of synthetic (22R)-adenosylhopane, indicating that HpnH catalyzes stereoselective C−C formation between C29 of diploptene and C5′ of 5′-deoxyadenosine. Further, the HpnH reaction in D₂O-containing buffer revealed that a D atom was incorporated at the C22 position of adenosylhopane. Based on these results, we propose a radical addition reaction mechanism catalyzed by HpnH for the formation of the C₃₅ bacteriohopane skeleton.     

The thiosulfinyl group serves as a stereogenic center and shows diamagnetic anisotropy similar to that of the sulfinyl group

The pseudotetrahedral geometry of the thiosulfinyl group (>S=S) in the thionosulfite which was prepared by treatment of cis-3,4-di-tert-butylthiolane-3,4-diol with 1,1'-thiobisbenzimidazole is stable enough to allow the isolation of two diastereomers. X-ray crystallographic analysis revealed that the configuration of the >S=S group of the major diastereomer (45% isolated yield) is syn to the thiolane ring, while that of the minor diastereomer (10% isolated yield) is anti to the thiolane ring. 1H NMR spectrum analysis clarified that the shielding and deshielding zones of the >S=S group are similar to those of the >S=O group. Chemical properties of the >S=S group toward thermolysis, hydrolysis, and oxidation were clarified. The absorptions or bands in the UV/vis, IR, and Raman spectra, which originate from the >S=S group, were assigned on the basis of the B3LYP/6-31G* level calculations.     

Quantitative Approximation to the Ordered Dirichlet Distribution under Varying Basic Probability Spaces

An approximate expansion of a sequence of ordered Dirichlet densities is given under the set-up with varying dimensions of the relating basic probability spaces. The problem is handled as the approximation to the joint distribution of an increasing number of selected order statistics based on the random sample drawn from the uniform distribution U(0, 1). Some inverse factorial series to the expansion of logarithmic function enable us to give quantitative error evaluations to our problem. With the help of them the relating modified K-L information number, which is defined on an approximate main domain and different from the usual ones, is accurately evaluated. Further, the proof of the approximate joint normality of the selected order statistics is more systematically presented than those given in existing works. Concerning the approximate normality the modified affinity and the half variation distance are also evaluated.     

Resource pricing games on graphs: existence of Nash equilibria

In this letter, we consider a non-cooperative resource pricing game on a graph where sellers (i.e., players) set the prices for their own resources to maximize the payoffs and buyers migrate to seek the least expensive resources. We present a model for the resource pricing game and prove the existence of Nash equilibria on regular and hierarchical graphs. The results obtained are applicable to the study of market economies, social networks and computer networks where individuals trade resources in a spatially extended environment.