On density of transitive operator algebras

In this paper we study the transitive algebra question by considering the invariant subspace problem relative to von Neumann algebras. We prove that the algebra (not necessarily ∗) generated by a pair of sums of two unitary generators of L(F_∞) and its commutant is strong-operator dense in B(H). The relations between the transitive algebra question and the invariant subspace problem relative to some von Neumann algebras are discussed.     

Optical properties of PbSe quantum dots doped in borosilicate glass

PbSe quantum dots (QDs) were synthesized in borosilicate glass and their optical properties were investigated. The typical quantum confinement effects were clearly observed from the absorption when the average radii of the QDs changed from 1.7 to 3.1 nm. Photoluminescence from PbSe QDs was achieved in 1.1–2.2 μm wavelength region that covers the entire fiber-optic telecommunication window. Borosilicate glasses containing controlled size of PbSe QDs provide potentials for the fiber-optic amplifiers.     

Influence of silver nanoclusters on formation of PbS quantum dots in glasses

Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag₂O, and the influence of Ag₂O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag₂O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses.     

Preparation and third-order optical nonlinearity of glass ceramics based on GeS2–Ga2S3–CsCl pseudo-ternary system

Chalcohalide glass-ceramics based on GeS₂–Ga₂S₃–CsCl pseudo-ternary system were prepared by heat treatment method. X-ray diffraction and scanning electron microscope studies confirmed the formations of Ga₂S₃ and GeS₂ phase grains with sizes of 2–5 and 80 nm, respectively. Z-scan technology was employed to investigate the third-order nonlinear optical characteristics of both precursor glass and its glass ceramics at 800 nm. The results show that nonlinear refractive index n₂ as well as nonlinear absorption coefficient β increase after heat treatment, which is due to quantum effects, and the largest n₂ of the glass ceramics is 4.3 × 10^? 11 esu which is 4 times larger than that of the host.     

Kinetic studies on the oxidation of carbon monoxide over pure,reduced, and doped indium sesquioxides

Kinetic studies on the oxidation of carbon monoxide have been carried out between 413 and 473 K at different partial pressures of carbon monoxide and oxygen by means of the static method using vacuum-activated, hydrogen-reduced, and NiO-doped In₂O₃ semiconductors as catalysts. A strong carbon dioxide inhibiting effect is observed. The experimental data satisfactorily fit an equation derived by assuming the controlling step to be the adsorption of gaseous oxygen on the surface of catalyst. CO and CO₂ adsorb on the lattice oxygens (O), while O₂ adsorbs on the oxygen vacancies (V) formed by vacuum-activation, H₂-reduction, and NiO-doping of In₂O₃. When CO₂ formed during the reaction is removed by means of liquid nitrogen trap, the oxidation is found to be first-order with respect to CO and to be half-order with respect to O₂. The concentration of oxygen vacancy in the solid catalyst is shown to be the controlling factor for the oxidation of carbon monoxide. A possible reaction mechanism can be explained by the n-type character of In₂O₃ and proposed from the experimentally obtained kinetic data and conductivities.     

Chronic activation of CREB and p90RSK in human epileptic hippocampus

Mesial temporal lobe epilepsy (MTLE) is associated with severe neuronal death and reactive gliosis in hippocampus. However, the molecular mechanisms underlying these pathological changes remain unanswered. ERK has been reported chronically activated in reactive glia of human epileptic hippocampus. In the present study, we investigated which of the downstream signaling molecules of ERK would be involved in MTLE. Western blot analysis demonstrated that CREB and p90RSK were strongly activated in MTLE patients. Increase in the active forms of CREB and p90RSK resulted not only from the increase in their phosphorylation levels but also from the increase in the protein levels. Activation of CREB and p90RSK was noted in the whole subfields of hippocampus with Ammon's horn sclerosis (AHS) representing a distinctive cellular distribution. However, the common major change was present in proliferating reactive astrocytes. In contrast, their activation was not significant in adjacent temporal lobes despite the presence of a number of astrocytes expressing high levels of GFAP. Our results demonstrate that chronic activation CREB and p90RSK in the epileptic hippocampus may be closely associated with the histopathological changes of AHS.     

Separation of theophylline and its analogues by micellar electrokinetic chromatography: application to the determination of theophylline in human plasma.

Micellar electrokinetic chromatographic separation of theophylline and its analogues was investigated using sodium dodecyl sulphate (SDS) as a micellar phase. The effects of pH, micelle concentration, applied voltage and temperature on the separation and preliminary quantitative analysis were studied for the determination of theophylline in human plasma. The data indicate that this technique could be used as the reference or routine method of theophylline measurement in therapeutic drug monitoring.     

Synthesis of dibenzo‐16‐crown‐5 compounds with pendant ester and ether groups

Structurally related dibenzo‐16‐crown‐5 lariat ethers with pendant ester and ether groups are prepared. Structural variations within the series of alkyl lariat ether esters include changes in the O‐alkyl group, attachment site and nature of the lipophilic group, and length of the spacer, which connects the ester group to the polyether framework. Also synthesized are bis(crown ether) diesters with two dibenzo‐16‐crown‐5 or two dicyclohexano‐16‐crown‐5 units and two ester groups connected to each other by a linker of varying length. Synthetic strategies for the preparation of these lariat ethers with pendant ester‐ and ether‐containing side arms are described.     

Facile palladium-catalysed synthesis of 1-aryl-1H-indazoles from 2-bromobenzaldehydes and arylhydrazines

2-Bromobenzaldehydes react with arylhydrazines in toluene at 100 [degree]C in the presence of a catalytic amount of a palladium catalyst and phosphorus chelating ligands such as 1,1[prime or minute]-bis(diphenylphosphino)ferrocene and 1,3-bis(diphenylphosphino)propane along with NaO-t-Bu to afford 1-aryl-1H-indazoles in good yields.     

Mid-infrared light emission characteristics of Ho3+-doped chalcogenide and heavy-metal oxide glasses

Emission characteristics of Ho³⁺-doped heavy-metal oxide and chalcogenide glasses were investigated and compared with those of conventional oxide glasses. In addition to the fluorescence at approximately 1.2 m (5/6 5/8) and 2.0 m (5/7 5/8), another mid-infrared emission was observed at 2.9 m from the transition 5/6 5/7. The calculated radiative transition probability and multiphonon decay rate of the latter transition using Judd-Ofelt analysis indicated that the occurrence of the 2.9 m fluorescence was directly related to the low vibrational phonon energy of the host glasses.