Kinetics and dynamics of N2 formation in a steady-state N2O + CO reaction on Pd(110)

The N(2)O decomposition kinetics and the product (N(2) and CO(2)) desorption dynamics were studied in the course of a catalyzed N(2)O+CO reaction on Pd(110) by angle-resolved mass spectroscopy combined with cross-correlation time-of-flight techniques. The reaction proceeded steadily above 400 K, and the kinetics was switched at a critical CO/N(2)O pressure ratio. The ratio was about 0.03 at 450 K and reached approximately 0.08 at higher temperatures. Below it, the reaction was first order in CO, and negative orders above it. Throughout the surveyed conditions, the N(2) desorption sharply collimated along about 45 degrees off the normal toward the [001] direction. Desorbing N(2) showed translational temperatures in the range of 2000-5000 K. It is proposed that the decomposition proceeds in N(2)O(a) oriented along the [001] direction. On the other hand, the CO(2) desorption sharply collimated along the surface normal, showing a translational temperature of about 1600 K.     

Optical resolution of various amino acids using a supported liquid membrane encapsulating a surfactant-protease complex

We have encapsulated a surfactant-protease complex (the main protease used being alpha-chymotrypsin) in an organic phase of a supported liquid membrane (SLM) for the optical resolution of various amino acids. L-Isomers of amino acids were enantioselectively permeated through the SLM. The mechanism of the amino acid permeation through the SLM was considered to be as follows; an L-amino acid was enantioselectively esterified with ethanol by a surfactant-protease complex encapsulated in the SLM, and the resulting L-amino acid ethyl ester dissolved into the organic phase of the SLM and diffused across the SLM. Another surfactant-alpha-chymotrypsin complex in the receiving phase catalyzed ester hydrolysis to produce the initial L-amino acid and ethanol, which are water-soluble. Thus, the L-amino acid was selectively transported to the receiving phase through the SLM on the basis of the molecular recognition of the surfactant-protease complex in the SLM. It was found that the catalytic activity and enantioselectivity of the surfactant-protease complex governed the permeate flux of amino acids and the enantiomeric excess in the membrane separation.     

Comb-shaped poly(ethylene glycol)-modified subtilisin Carlsberg is soluble and highly active in ionic liquids

Subtilisin Carlsberg conjugated with comb-shaped poly(ethylene glycol) was solubilized in common ionic liquids without adding water, and exhibited higher transesterification activity in an ionic liquid, [Emim][Tf2N], than in organic solvents commonly used for enzymatic biotransformation.     

Preparation of palladium film by coating photolysis process using KrF or ArF excimer laser

The preparation of palladium (Pd) films has been investigated using KrF or ArF laser irradiation on a Pd acetate (PdAc) coated substrate. A crystalline Pd film could be obtained by KrF laser irradiation (fluence = 15-40 mJ/cm²) but PdAc was found to remain in the film. An increase in the substrate temperature to 423 K decreased the inclusion of the unreacted precursor and produced a better crystallinity. An amorphous and uniform Pd film composed of very fine particles was found to be formed by this process under reduced pressure, which is probably due to the preferential ablation of the crystalline nuclei. ArF laser irradiation is more effective for decomposing the PdAc and for producing a Pd film with a better crystallinity and no (or smaller) organic inclusion.     

Solid state amorphization in Cu---Hf multilayers studied by time-differential perturbed-angular correlation

The time differential perturbed angular correlation spectra of the Cu---Hf multilayers and the change in the spectra during the amorphous phase change have been measured. The mechanism for the phase change of the multilayers is discussed.     

Spin-waves in Heisenberg ferro- and antiferromagnet

We report the result of the spin-wave spectrum, magnetic susceptibility, specific heat and short range correlation for one and two-dimensional Heisenberg antiferromagnet and ferromagnet by using the variational theory at finite temperatures. The spin-wave spectrum in one-dimensional antiferromagnet at T = 0, is in good agreement with the exact theory of Cloizeaux and Pearson.     

Formation and characterization of crystalline molecular arrays of gas molecules in a 1-dimensional ultramicropore of a porous copper coordination polymer

Molecules and atoms confined in a nanospace may have properties distinctly different from those of the bulk fluid, owing to the formation of a specific molecular array characteristic of nanospace. In situ synchrotron powder X-ray diffraction measurements have been used to observe confined guest molecules such as N2, O2, Ar, and CH4 in the well-regulated ultramicropore of a copper coordination polymer, 1 ([Cu2(pzdc)2pyz]: pzdc = 2,3-pyrazinedicarboxylate and pyz = pyrazine). The obtained crystal structures indicate that guest molecules are confined in a linear fashion to form crystalline-like regular ordered arrays, in contrast to the situation in the gas and liquid state, even at temperatures above the boiling point, and the ordered arrays are characteristic of the kind of gas molecule and the geometrical and potential properties of the ultramicropore of 1.     

Glycosides of Atractylodes ovata

A new coumarin glycoside and a new glycoside of an acetylene derivative were isolated from the water-soluble portion of the methanolic extract of Atractylodes ovata rhizome together with eight known compounds. Their structures were characterized as scopoletin beta-D-xylopyranosyl-(1-->6)-beta-D-glucopyranoside and (2E)-2-decene-4,6-diyne-1,8-diol 8-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside, respectively, based on chemical and spectroscopic investigations. A comparison of the polar constituents among Atractylodes japonica, Atractylodes lancea, and A. ovata is led to the conclusion that A. ovata is distinguishable from A. lancea and A. japonica, as also shown by phylogenetic analysis.