Effect of included guest molecules on the normal state conductivity and superconductivity of beta''-(ET)(4)[(H(3)O)Ga(C(2)O(4))(3)].G (G = pyridine,nitrobenzene)

Normal state conductivity and superconductivity together with bulk magnetic susceptibility and magnetization measurements have been measured for two molecular charge-transfer salts: beta' '-(ET)4[(H3O)Ga(C2O4)3]G (ET = bis(ethylenedithio)tetrathiafulvalene, G = pyridine for compound I and nitrobenzene for compound II). With the exception of the included guest molecules (G) the crystal structures are almost identical. Both show minima in their electrical transport at 130 K for I and at 160 K for II, but at lower temperatures their behaviors differ markedly. The resistance of I reaches a maximum at 50 K with a further small peak at 2 K and possible superconductivity only below 2 K, whereas that of II increases continuously down to 7.5 K, where an abrupt transition to a superconducting state occurs.     

Emission-spectrometric determination of trace non-rare earth elements in yttrium oxide using AgF-Ga2O3 mixed carrier

Summary An emission-spectrometric method is described for the quantitative determination of traces of non-rare earth elements in yttrium oxide, employing addition of AgF-Ga₂O₃ mixed carrier. This addition effects an increase of the rate of evaporation of the analytical elements and of the number of atoms in the arc plasma. It enhances the sensitivity of the analytical elements to a larger extent than other carriers and permits the determination of microquantities of the elements (Mg, Ca, Mn, Co, Fe, Pb, Cu, Cd, Al, B, Sn, As, Bi) within limits of detection from 0.1 to 13 ppm in high-purity yttrium oxide. The coefficients of variation are less than 20%.

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Emissionsspektrometrische Bestimmung von nicht zu den Seltenen Erden gehörenden Elementspuren in Yttriumoxid mit Hilfe eines AgF-Ga₂O₃ -Trägergemisches

Zusammenfassung Das Trägergemisch bewirkt eine Erhöhung der Verdampfungsgeschwindigkeit der zu bestimmenden Elemente und der Anzahl der Atome im Bogenplasma. Es verbessert mehr als andere Träger die Empfindlichkeit und ermöglicht die Bestimmung von Mikromengen der Elemente (Mg, Ca, Mn, Co, Fe, Pb, Cu, Cd, Al, B, Sn, As, Bi) in hochreinem Yttriumoxid mit Nachweisgrenzen von 0,1–13 ppm. Die Variationskoeffizienten liegen unter 20%.

     

1,4-cycloheptylene and the related allylic diradicals. Thermal nitrogen extrusion from 6,7-diazabicyclo[3.2.2]Non-6-enes

Thermal nitrogen extrusion of 2-methylene-6,7-diazabicyclo[3.2.2]non-6-enes and 6,7- diazabicyclo[3.2.2]nona-2,6-diene,6 proceeded easily to give closure and cleavage products $\text{via}$ the corresponding 5-methylene-1,4-cycloheptylenes and 4-cyclohepten-1,3-ylenes, respectively.     

Studies of Japanese lacquer: Urushiol dimerization by the coupling reaction between urushiol quinone and a triolefinic component of urushiol

Previously, the formation of urushiol quinone from urushiol was demonstrated in the laccase-catalyzed oxidation process of the sap of the Japanese lacquer tree (Rhus vernicifera D.C.) or of lacquer formed from it. This paper presents the results of the investigation on the participation of urushiol quinone in the oxidative polymerization and crosslinking of the sap or the lacquer. The polymeric urushiol was obtained by the fractionation of the mildly oxidized sap (Japanese lacquer), and a specific dimeric urushiol was isolated from it by thin-layer chromatography (TLC). Structural analysis of the dimer illustrated that it has a conjugated triene structure and may be formed by a coupling reaction between urushiol quinone and a triolefinic component of urushiol. Further support for this was given by the spectroscopic study of the reaction between 4-tert-butyl-o-quinone and the triolefinic component of dimethylurushiol, and by the isolation and identification of the coupling product between them.     

Optimal laser control of ultrafast photodissociation of I2- in water: mixed quantum/classical molecular dynamics simulation

A linearized optimal control method in combination with mixed quantum/classical molecular dynamics simulation is used for numerically investigating the possibility of controlling photodissociation wave packets of I(2)(-) in water. Optimal pulses are designed using an ensemble of photodissociation samples, aiming at the creation of localized dissociation wave packets. Numerical results clearly show the effectiveness of the control although the control achievement is reduced with an increase in the internuclear distance associated with a target region. We introduce effective optimal pulses that are designed using a statistically averaged effective dissociation potential, and show that they semiquantitatively reproduce the control achievements calculated by using optimal pulses. The control mechanisms are interpreted from the time- and frequency-resolved spectra of the effective optimal pulses.     

Studies on polymers containing functional groups. II. Polymerization behavior of o-hydroxystyrene

The polymerization behavior of o-hydroxystyrene with free-radical and cationic initiators and without an initiator was examined. The structures thus obtained were estimated. Although polymerization behavior of o-hydroxystyrene was rather complicated, according to the results, it appeared that each polymerization more or less might simultaneously follow the two types of mechanisms: normal vinyl polymerization and polymerization through the addition to benzene nuclei. The proportion of addition to benzene nuclei was considered to be highest in the polymerization with BF₃·(OEt)₂ and lowest in that with azobisisobutyronitrile. Degrees of polymerization of these polymers were low in all cases (42–82). Some brief experiments on copolymerization of o-hydroxystyrene were carried out.     

Effect of hydrophobic amino acids on the conformational change of decapeptides in micellar environments

A series of peptides containing various hydrophobic amino acids [methionine (Met), leucine (Leu), norleucine (Nle), phenylalanine (Phe), 2-aminooctanoic acid (Aoc), and 2-aminodecanoic acid (Ade)] were synthesized and their conformations were studied using circular dichroism (CD) spectroscopy in different solvents such as water, methanol, and aqueous solution of ammonium tetradecanesulfonate. Peptides containing hydrophobic amino acids with linear side chains formed -sheets in water and methanol. Electrostatic interaction between the charged side chain (lysine) and a micelle consisting of an anionic surfactant, ammonium tetradecanesulfonate, is necessary for the formation of -helices in micellar environments. The conformational transition from -helix to -sheet structure required moderate hydrophobicity and linear side chains. This conformational transition depended on the surfactant concentration.     

A simple and easy access to 3-N-alkyl-5-vinyloxazolidinones mediated by palladium-phosphine catalysts

A new entry for the synthesis of 3-alkyl substituted 5-vinyloxazolidin-2-one derivatives 2 from cis-2-butenylene-1,4-dicarbonate 1 and primary amines mediated by palladium-phosphine catalysts is described. The scope and limitation, a plausible mechanism, and an asymmetric version of the reaction are also discussed.     

Multielement determination in tobacco leaves by photon activation analysis

A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is quite simple and gives good reproducible results for at least 12 elements.