Kinetics of the dehydration of boehmites prepared under different hydrothermal conditions

The kinetics of the dehydration of five boehmites, which were prepared under different hydrothermal conditions (300°C, 85 atm, 20 h — 150°C, 4.5 atm, 5 h), were studied by means of isothermal TG at an air pressure of 150 mm Hg and at a constant flow rate of nitrogen (30 ml min^?1) containing water vapor of partial pressures between 10^?4 and 23.8 mm Hg. It was found that the dehydration temperature of boehmites was lowered as the preparation conditions became more mild. Moreover, the rate-controlling step of the dehydration of boehmites varied with their preparation conditions. The water vapor pressure led to decreases in the rate of dehydration.     

Permeability of hydrophilic and hydrophobic Shirasu-porous-glass (SPG) membranes to pure liquids and its microstructure

Morphological properties of hydrophilic and hydrophobic Shirasu-porous-glass (SPG) membranes were investigated over a wide range of mean pore sizes (0.252–20.3 μm) by liquid permeability measurements, scanning electron microscopy and Hg porosimetry. Hydrophobic modification of membrane surface was made by surface coating with silicone resin. The results are discussed using the non-uniform capillary bundle model of membrane permeability. The mean pore tortuosity of 1.28 was kept constant over the whole range of mean pore sizes investigated. The SEM images confirmed that the geometry of pore network was similar for all SPG membranes, irrespective of their mean pore size. The span of pore size distribution ranged from 0.28 to 0.68 and the number of pores per unit cross-sectional membrane area from 10⁹ to 10¹³ m⁻². The membrane resistance was unchanged after surface treatment with silicone resin, which means that the pores were not plugged by the resin, even in the submicron range of mean pore sizes.     

The circular bacteriocins gassericin A and circularin A

Gassericin A, a bacteriocin produced by Lactobacillus gasseri LA39, shows antibacterial activity against a number of Gram-positive food-borne pathogenic bacteria. Circularin A produced by Clostridium beijerinckii ATCC25752 is active against C. tyrobutyricum, a known cheese-spoilage bacterium. Both bacteriocins were purified to homogeneity from culture supernatants by reverse-phase chromatography and the subsequently determined amino acid sequences were used to clone the bacteriocin structural genes. Mature gassericin A and circularin A are class V circular bacteriocins comprised of 58 and 69 amino acid residues, respectively. Both bacteriocins are resistant to several peptidases and proteases, as are other cyclic bacteriocins. Heterologous expression of gassericin A in Escherichia coli was used to produce a non-cyclic mature peptide, which was shown to have a specific activity 173-fold lower than the circular molecule. The minimal region for production and secretion of active circularin A is comprised of five genes, as was deduced by heterologous gene expression in Enterococcus faecalis. Gassericin A and circularin A have limited mutual similarity in their primary sequences. Unlike most bacteriocins, including gassericin A, circularin A has a three-amino-acid-leader sequence.     

Totally synthetic steroid heterocycles. Part 7.. A facile approach to 16-oxa-D-homoestrogens

In search of biologically active modified steroids, novel 16-oxa-D-homoestrone and -D-homoestradiol 3-methyl ethers were synthesized from 16-oxa-3-methoxy- D -homoestra-1,3,5(10),8,14-pentaen-17a-one. The straightforward synthesis involved stereoselective two-step reduction of the 8,14-diene system. The B/C stereoisomers were also derived from the estrapentaene. The stereostructures of these heterocyclic estrogens were determined on the basis of their spectral data.     

The ortho-lithiation of phenyl groups and α-lithiation of alkyl groups of thiophosphoryl compounds

Diphenylphosphinothioyl compounds were ortho-lithiated and alkyldiphenyl phosphine sulfides were α-lithiated and the resulting lithio compounds reacted to give the corresponding $\text{o}$- and α-substituted products.     

Protection of hydroxy groups by intramolecular oxidative formation of methoxybenzylidene acetals with DDQ

On DDQ oxidation under anhydrous conditions, hydroxy groups located at α or β position to methoxybenzyl ether groups were readily protected by the intramolecular oxidative formation of acid-sensitive methoxybenzylidene acetals, which were further oxidized to alkali-sensitive hydroxy esters in the presence of H₂O.     

Enantioselective synthesis of (2R,4'R,8'R)-alpha-tocopherol (vitamin E) based on enzymatic function

Syntheses of (S)-chroman-2-carboxaldehyde congener 1 and (S)-chiral isoprene unit 3 were achieved based on the enzymatic acetylation of (+/-)-chroman-2-methanol 6 and (+/-)-(2,3)-anti-2-methyl-3-(p-methoxyphenyl)-1,3-propane diol 12, respectively. Synthesis of the side-chain part corresponding to (3R,7R)-3,7,11-trimethyldodecan-1-ol 27 was achieved by the coupling reaction of (S)-3 and (R)-3,7-dimethyloctyl iodide 4. The Wittig reaction of (3R,7R)-phosphonium salt 2 derived from (3R,7R)-27 and (S)-1 gave the olefin 28 which was subjected to catalytic hydrogenation to afford (2R,4'R,8'R)-alpha-tocopherol.     

No-Cloning Theorem,Kochen-Specker Theorem,and Quantum Measurement Theories

The usual no-cloning theorem implies that two quantum states are identical or orthogonal if we allow a cloning to be on the two quantum states. Here, we investigate a relation between the no-cloning theorem and the projective measurement theory that the results of measurements are either + 1 or − 1. We introduce the Kochen-Specker (KS) theorem with the projective measurement theory. We result in the fact that the two quantum states under consideration cannot be orthogonal if we avoid the KS contradiction. Thus the no-cloning theorem implies that the two quantum states under consideration are identical in that case. It turns out that the KS theorem with the projective measurement theory says a new version of the no-cloning theorem. Next, we investigate a relation between the no-cloning theorem and the measurement theory based on the truth values that the results of measurements are either + 1 or 0. We return to the usual no-cloning theorem that the two quantum states are identical or orthogonal in the case.