Thermal quenching of thermoluminescence in TLD-200, TLD-300 and TLD-400 after β-irradiation

The dosimetric characteristics of many TL materials are influenced by changes in location, size and shape of the glow curves due to changes in the heating rate. In this study, the effect of heating rate on the integrated peak areas of CaF₂:Dy (TLD-200), CaF₂:Tm (TLD-300) and CaF₂:Mn (TLD-400) crystals have been investigated after β-irradiation. It was observed that the peak temperatures of all peaks shifted to the high temperature sides and the integrated peak areas decrease as the heating rate increases due to thermal quenching, whose efficiency increases as temperature increases.     

Fabrication of CuO/T-ZnOw nanocomposites using photo-deposition and their photocatalytic property

CuO/tetrapod-like ZnO whisker (T-ZnOw) nanocomposites were successfully synthesized using a simple photo-deposition method. Some nanocomposites exhibit remarkably improved photocatalytic property, while the extents of the improvements vary with different Cu/Zn molar ratios and polyethylene glycol (PEG) concentrations. Moreover, it is found that excessively high Cu/Zn molar ratio or PEG concentration would reduce the photocatalytic property of the nanocomposites. A direct relationship between the morphology and the photocatalytic property of CuO/T-ZnOw was established and then analyzed by discussing the photocatalytic mechanism of the CuO/T-ZnOw nanocomposites.     

Fine structure of the isoscalar giant quadrupole resonance in Ca due to Landau damping?

The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in ⁴⁰Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at Ep=200 MeV$E_{\mathrm{p}}=200\text{MeV}$. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon–nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for ⁴⁰Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle–two-hole (2p–2h) states.     

Lu2SiO5:Ce透明薄膜改性及其发光性能

Lu2SiO5:Ce具有高密度、高光产额、快衰减等优点,是一种性能优异的新型X射线闪烁薄膜材料.本文采用溶胶-凝胶工艺和旋涂技术,以无机盐为原料、2-甲氧基乙醇为溶剂、聚乙二醇(PEG)为改性剂,在石英基片上成功制备出Lu2SiO5:Ce透明薄膜,较为详细地研究了PEG对该薄膜发光性能的影响.结果表明当采用浓度为12....     

High‐molecular‐weight symmetrical multiblock copolymers: Synthesis by RAFT polymerization and characterization

High‐molecular‐weight (MW) symmetrical multiblock copolymers, based on the hydrophobic monomers styrene (Sty) and methyl methacrylate (MMA), and the more polar monomer, 2‐vinyl pyridine (2VPy), were prepared using stepwise reversible addition‐fragmentation chain transfer polymerization. All copolymers shared a common poly(ethylene glycol) (PEG) midblock, introduced as a bifunctional macromolecular chain transfer agent. In total, five ABA triblock copolymers, five ABCBA pentablock terpolymers, and two ABCDCBA heptablock quaterpolymers (comprising four different monomer types) were synthesized. The MWs of the multiblock polymers were determined using gel permeation chromatography (GPC) and proton nuclear magnetic resonance (¹H NMR) spectroscopy, with the latter values being closer to the theoretically expected, whereas GPC MW distributions were relatively narrow, broadening with the number of blocks. The compositions of the synthesized polymers, as determined by ¹H NMR spectroscopy, were also close to the expected values. Finally, films cast from chloroform solutions of the pentablock terpolymers P2VPy‐b‐PSty‐b‐PEG‐b‐PSty‐b‐P2VPy, PSty‐b‐PMMA‐b‐PEG‐b‐PMMA‐b‐PSty, and P2VPy‐b‐PMMA‐b‐PEG‐b‐PMMA‐b‐P2VPy examined using transmission electron microscopy exhibited PSty and PMMA cylinders (first two) and lamellae (third terpolymer). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4957–4965     

Copper‐catalyzed one‐pot synthesis of propargylamines via C?H activation in PEG

An efficient and convenient three‐component A³ coupling reaction of aldehyde, amine and alkyne via C? H activation with CuI alone as the catalyst in PEG is developed, providing a wide range of propargylamines with yields ranging from moderate to excellent. Additionally, the catalyst system was recovered and reused several times without evident loss in activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Chromatography of glycols. Regularities in the retention of C3−C6 branched glycols in gas-solid and gas-liquid chromatography

Summary Linear correlation between the major physico-chemical properties of glycols and their relative retention volumes measured by gas-solid (GSC) and gas-liquid (GLC) chromatography is shown. The coefficients of the linear regression equations describing the relationship between the relative retention volumes and the physico-chemical parameters (boiling point, density, etc.) are given. The values of the change in the free energy for the stationary phases studied are given as well as the increments of this change per −CH₂- and CH₃-group. The main factors determining the retention of branched glycols on Polysorb, Tween and poly(ethylene glycol) are shown to be the distance between the hydroxyl groups in their molecules, the presence of alkyl substituents and the type and the number of these substituents.     

Etude thermoanalytique et spectrale de l'interaction lorazepam/PEG 6000

Résumé The solubility and rate of dissolution of a poorly-soluble active principle are of importance when substances are destined for oral administration. Physical blends in wich drug and carrier are able to form particular compositions, such as a eutectic, may exibit an increased rate of dissolution. In this work the interactions lorazepam and PEG 6000, were examined, the particular thermal behaviour of lorazepam being taken into account. An eutectic was obtained and its composition was studied by means of differential scanning calorimetry, thermomicroscopy, infrared spectroscopy and X-ray methods.

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Zusammenfassung Bei der oralen Darreichung von Substanzen ist die L?slichkeit und Aufl?sungsgeschwindigkeit schlechtl?slicher aktiver Komponenten von gro?er Bedeutung. Physikalische Gemische, in denen Wirkstoffe und Tr?gersubstanzen besondere Zusammensetzungen wie zum Beispiel Eutektika zu bilden in der Lage sind, k?nnen eine erh?hte Aufl?sungsgeschwindigkeit zeigen. Vorliegend wird die Wechselwirkung zwischen Lorazepam und PEG 6000 untersucht, wobei das besondere thermische Verhalten von Lorazepam berücksichtigt wurde. Es wurde ein Eutektikum erhalten und dessen Zusammensetzung mittels DSC, Thermomikroskopie, Infrarotspektroskopie und R?ntgenmethoden untersucht.

     

The photochemical metal organic deposition of manganese oxide films from films of manganese(II) 2-ethylhexanoate: a mechanistic study

The photochemistry of thin films of manganese(II) 2-ethylhexanoate to produce manganese oxide films is presented. Thin films of manganese(II) 2-ethylhexanoate can be cast onto silicon wafers by spin coating. The FTIR spectroscopy of these films suggests they exist as chains or clusters with the manganese(II) centers linked by bridging 2-ethylhexanoate ligands. The initial photochemical reaction results in the loss of the bridging 2-ethylhexanoate ligands and the formation of monomeric manganese(II) 2-ethylhexanoate. In this process approximately 60% of the bridging 2-ethylhexanoate ligand is converted to chelating 2-ethylhexanoate while the other 40% fragments to form CO₂, heptane and heptene. Further photolysis resulted in the conversion of the remaining 2-ethylhexanoate ligand to form CO₂, heptane and heptene. The film consisted of manganese(II) oxide although the surface of the film was more oxidized and had carbon impurity on it. Annealing the film resulted in the conversion to polycrystalline α-Mn₂O₃.     

Effect of polyethylene glycol on the crystallization and impact properties of polylactide‐based blends

Polylactide (PLA) was plasticized by polyethylene glycols (PEGs) with five different molecular weights (M_w = 200–20,000 g/mol). The effects of content and molecular weight of PEG on the crystallization and impact properties of PLA were studied by wide‐angle X‐ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, and V‐notched impact tests, respectively. The results revealed that PEG‐10,000 could significantly improve the crystallization capacity and impact toughness of PLA. When the PEG‐10,000 content ranged from 0 to 20 wt%, the increases in both V‐notched Izod and Charpy impact strengths of PLA/PEG‐10,000 blends were 206.10% and 137.25%, respectively. Meanwhile, the crystallinity of PLA/PEG‐10,000 blends increased from 3.95% to 43.42%. For 10 wt% PEG content, the crystallization and impact properties of PLA/PEG blends mainly depended upon PEG molecular weight. With increasing the M_w of PEG, the crystallinity and impact strength of PLA/PEG blends first decreased and then increased. The introduction of PEG reduced the intermolecular force and enhanced the mobility of PLA chains, thus improving the crystallization capacity and flexibility of PLA. Copyright © 2015 John Wiley & Sons, Ltd.