Determination of carbohydrates by condensation with 3-methyl-2-benzothiazolinonehydrazone

The condensation reactions obtained by heating carbohydrates with 3-methyl-2-benzothiazolinonehydrazone (MBTH) in alkaline solution containing 2-methoxyethanol are utilized. The absorbance of the product is measured at 390 nm against the reagent blank. D-Glucose (50–350 nmol) can be determined accurately with coefficients of variation less than 1.5%. Other reducing carbohydrates give similar results. The selectivity of this method is discussed.     

Porous polystyrene microspheres having dimpled surface structures prepared within micellar assemblies of amphiphilic silica particles in water

Production of porous polystyrene microspheres having dimpled surface structures was demonstrated using amphiphilic and hydrophobic silica particles as structure-directing agents.     

Syntheses of anolignans A and B using ruthenium-catalyzed cross-enyne metathesis.

Anolignans A and B were synthesized using ruthenium-catalyzed cross-enyne metathesis as the key steps. The 1,3-diene moieties of these natural products were constructed by the introduction of the methylene parts of ethylene into alkyne using Grubbs' catalyst.     

A systematic preparation of new contracted Gaussian- type orbital sets. VII. MINI-3, MINI-4, MIDI-3, and MIDI-4 sets for transition metal atoms

Two minimal contracted Gaussian-type orbital (CGTO ) sets are developed for the transition metal atoms. The expansion terms for the first set, MINI -3, are 4, 3, 3, and 3 for s-type CGTO s and others are all three. The abbreviation would be (4333/33/3) where the slash divides symmetry. The expansion terms for the other set, MINI -4, is (4333/43/4). The split-type basis sets, MIDI -3 and MIDI -4, are derived directly from MINI -3 and MINI -4, MINI -3 and MIDI -3 provide the outer-shell orbital energies which are far better than those by single-zeta (SZ ) STO s. MINI -4 and MIDI -4 provide the outer-shell orbital energies which are almost as good as those by double-zeta (DZ ) STO s. The total energies given by the present sets are better than those of SZ except for MINI -3 for Sc and Ti: the energies by MINI -4 and MIDI -4 are only 0.8–1.7 a.u. higher than DZ . The basis sets were tested on the Cu₂ molecule, where a large basis set was also used.     

Model potentials for molecular calculations. II. The spd-MP set for transition metal atoms Sc through Hg

Model potential parameters and valence orbitals were generated for the transition metal atoms Sc through Hg. They are named the spd-MPs and are supplementary to the sd-MPs presented in the preceding article. The outermost core np electrons were treated explicitly together with valence nd and (n + 1)s electrons, and the remaining electrons were replaced by a model potential. The model potential parameters and valence orbitals were determined in the same way as the sd-MPs. Major relativistic effects (via the mass velocity and Darwin terms) were also incorporated in the spd-MPs for the second-and third-row transition metal atoms. The results of numerical nonrelativistic Hartree-Fock (HF) calculations for the first-row transition metal atoms and of the quasirelativistic HF calculations with Cowan and Griffin's method for the second-row and third-row transition metal atoms were used as reference data in determination of the spd-MPs.     

Photophysical and photochemical processes in zeolite cavities: The effects of ion-exchanged alkalimetal cations on the excited states of xanthone and the photolysis of 2-pentanone

The characteristics properties of xanthone phosphorescence and of 2-pentanone photolysis in alkali metal cation-exchanged zeolites have been investigated to clarify the effect of the micro-environment of host-adsorbents on the photophysical and photochemical properties of guest-molecules in restricted void spaces. The enhancement of the phosphorescence yields of xanthone included in zeolites is observed by changing the exchangeablealkali metal cation from Li⁺ to Cs⁺. Simultaneously, the phosphorescence lifetimes were observed to continuously shorten by changing the cation from Li⁺ to Cs⁺. These results suggest that the external heavy-atom effect deriving from the alkali metal cations on the singlet-triplet transitions of xanthone molecules stabilized on alkali metal cations in the order of Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺. The yields for the photolysis of 2-pentanone included in zeolites increase with changing the alkali metal cation from Li⁺ to Cs⁺. IR investigations of the adsorption state of 2-pentanone indicate that strength of the interaction between the alkali metal cations and 2-pentanones decreases by changing the cation from Li⁺ to Cs⁺, which results in a longer lifetime of 2-pentanone. The selectivity of propylene formation is dramatically increased by changing the cation from Li⁺ to Cs⁺. The enhanced formation of propylene is asociated with the hydrogen absorption from propyl radicals by lattice oxygen, their basicity increasing by changing the cation from Li⁺ to Cs⁺. Thus, these changes in the zeolite cavities modified by exchanging cations caused significant effects not only on the excited state but also on the following chemical reactions of ketones.     

Periodate oxidation analysis of carbohydrates: Part 12. Rapid Determination of Aldehydes in the Oxidation Products of Oligoglycosides by the Dithioacetal Method

A rapid and convenient analysis for glycosidic linkages in oligoglycosides was developed by improving the ditbioacetal method. A sample (0.1–1 μmol) was oxidized with an aqueous or aqueous methanolic 0.05 M solution of sodium metaperiodate for 3 h at 50°C. An equivalent amount of silver nitrate was added and the mixture was evaporated to dryness. The residue was treated with a 2:1 (v/v) mixture of ethanethiol and trifluoroacetic acid for 10 min at 25°C, and subsequently trimethylsilylated with hexamethyldisilazane and trimethylchlorosilane for 30 min at 50°C. Gas chromatography of the product allowed the simultaneous determination of the conjugated aldehydes in the oxidation product with high reproducibility. The glycosidic linkages in various oligoglycosides were examined by this procedure.     

Seven germacranolides,eupaglehnins A,B, C,D, E,and F,and 2alpha-acetoxyepitulipinolide from Eupatorium glehni

Four new germacrane-type sesquiterpenoids with unsaturated acids as esters at the 8-position, two chlorine atom-containing lactones, 2alpha-acetoxyepitulipinolide, and 12 previously known compounds have been isolated from the MeOH extract of Eupatorium glehni (Compositae) and their structures have been determined on the basis of spectral data analyses.     

Photoinactivation of Virus Infectivity by Hypocrellin A

Abstract— We investigated the photoinactivation of virus infectivity by hypocrellin A and its mechanism. The titers of vesicular stomatitis virus (VSV) and human immunodeficiency virus type 1 (HIV-1), both of which are enveloped viruses, were reduced upon illumination with hypocrellin A in a concentration-dependent manner, whereas canine parvovirus, a nonenveloped virus, was not killed. The removal of oxygen or addition of sodium azide or bT-carotene both inhibited VSV inactivation. Mannitol and superoxide dismutase had no effect on VSV inactivation. These results indicate that singlet oxygen was involved in the process of VSV inactivation. Of the three major VSV membrane proteins, peripheral membrane protein M was most damaged by the hypocrellin A phototreatment.     

Optical damping constants in narrow gap semiconductors

Optical damping constants due to free carriers of HgSe, Zn _x Hg_1–x and Cd _x Hg_1–x Se were estimated from far infrared reflection spectra at 5 and 10 K. The damping mechanism was explained by the Drude type scattering below plasma frequency and by doubly ionized impurity scattering in the higher frequency range.