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Abstract: The effects of K2TiF6 on the dehydrogenation properties of LiAlH4 were investigated by solid-state ball milling. The onset decomposition temperature of 0.8 mol% K2TiF6 doped LiAlH4 is as low as 65 °C that 85 °C lower than that of pristine LiAlH4. Isothermal dehydrogenation properties of the doped LiAlH4 were studied by PCT (pressure–composition–temperature). The results show that, for the 0.8 mol% K2TiF6 doped LiAlH4 that dehydrogenated at 90 °C, 4.4 wt% and 6.0 wt% of hydrogen can be released in 60 min and 300 min, respectively. When temperature was increased to 120 °C, the doped LiAlH4 can finish its first two dehydrogenation steps in 170 min. DSC results show that the apparent activation energy (E a) for the first two dehydrogenation steps of LiAlH4 are both reduced, and XRD results suggest that TiH2, Al3Ti, LiF and KH are in situ formed, which are responsible for the improved dehydrogenation properties of LiAlH4. [Copyright &y& Elsevier]

• The Loei Fold Belt contains Late Carboniferous (304–299 Ma) basaltic and andesitic tuffaceous rocks and Late Triassic (224–236 Ma) andesite and rhyolite. • The Late Carboniferous and Late Triassic volcanic rocks were formed in a back-arc basin and continental arc setting respectively. • Magmatic events in the Loei Fold Belt occurred in four periods: Ordovician-Silurian, Late Devonian-Middle Permian, Early-Middle Triassic and Late Triassic. • The Nan belt and Luang Prabang-Loei belt were connected in a back-arc basin during Late Devonian to Carboniferous. The Loei Fold Belt is one of the most significant tectonic and metallogenic belts in the Indochina Block. However, origin and tectonic significance of volcanic rocks in several volcanic belts of this fold belt remain ambiguous. In this paper, we present new petrochemical data, zircon U-Pb ages and Lu-Hf isotopic data for volcanic rocks from the Loei Fold Belt in northwestern Laos. The basaltic and andesitic tuffaceous rocks have Late Carboniferous zircon U-Pb ages (304 ± 2.1 Ma and 299 ± 1.8 Ma respectively), and display both MORB-like and arc-like geochemical signatures. Zircon Lu-Hf isotopic analyses give highly positive ε Hf (t) values of 8.99–14.24, indicative of a metasomatic mantle source which formed in a back-arc basin environment. On the other hand, the andesite and rhyolite samples have zircon U-Pb ages ranging from 236 Ma to 224 Ma, erupted during the Late Triassic, and formed in a continental margin arc setting (e.g., enrichment of LREE, depletion in Nb-Ta, Sr, and positive ε Hf (t) values of 9.87–12.25). With a synthesis of available geochronological, petrochemical and isotopic data, magmatic events in the Loei Fold Belt occurred in four periods: Ordovician-Silurian (450–400 Ma), Late Devonian-Middle Permian (ca. 361–265 Ma), Early-Middle Triassic (250–237 Ma) and Late Triassic (ca. 236–200 Ma), with peaks in Triassic and Carboniferous. Accordingly, we propose a tectonic-magmatic evolution model for the Loei Fold Belt. The Luang Prabang-Loei belt was a spreading back-arc basin during the Late Devonian-Middle Permian, and connected with the Nan back-arc basin. The basin expanded to its largest extent in the Permian period and started subduction in the earliest Triassic; the successive subduction did not terminate until the Late Triassic. [ABSTRACT FROM AUTHOR]

A core-shell composite consisting of polypyrrole (PPy) nanofibers and TiO 2 was synthesized by using PPy nanofibers as the core and TiO 2 as the shell. The TiO 2 @PPy composite substrate was doped with Pd nanoparticles via chemical reduction. The resulting Pd–TiO 2 @PPy nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller (BET) adsorption analysis before it was utilized to fabricate a hydrogen sensor. Compared with sensors based on TiO 2 @PPy or PPy, the Pd–TiO 2 @PPy sensor was highly sensitive and selective to hydrogen gas, exhibiting a fast response time in air at room temperature. The Pd–TiO 2 @PPy-based sensor exhibited a sensitivity of 8.1% toward 1 vol% of H 2 gas, which is much larger than the sensitivities of sensors based on only TiO 2 @PPy and PPy nanofibers. The excellent reproducibility, stability and selectivity of the Pd–TiO 2 @PPy nanocomposite make it a high potential candidate for hydrogen sensors. [ABSTRACT FROM AUTHOR]

A ternary composite of polypyrrole (PPy), Prussian blue (PB), and graphene oxide (GO), PPy–PB–GO, was successfully prepared through spontaneous polymerization of pyrrole and formation of PB nanocubes on GO. The obtained nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The results indicate that the PPy-protected PB nanocubes were well dispersed on the GO. Electrochemical testing showed a specific capacitance of 525.4 F g −1 at a current density of 5 A g −1 in the potential range from −0.2 to 0.6 V, obtained in an electrolyte of 1 mol L −1 KNO 3 during the galvanostatic charge–discharge cycles, which is superior to the performance of binary cathode materials, including PPy–PB and PPy–GO nanocomposites. The as-prepared supercapacitor could retain a specific capacitance of 96% after 2000 cycles. It was confirmed that the three components—PPy, PB, and GO—led to the display of integrated electrochemical behavior and a resulting capacitor with enhanced performance. The significant enhancement in electrochemical performance of the ternary nanocomposite can be attributed to the synergistic effect of PPy-protected PB nanocubes dispersed on GO sheets with the pseudocapacitance from PB and PPy on the double-layer capacitance from GO. [ABSTRACT FROM AUTHOR]

A cobalt–boron/nickel–boron (Co–B/Ni–B) nanocomposite was synthesized in a two-step process by in situ reduction of nickel and cobalt salts. Characterization of the nanocomposite using X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller adsorption analysis showed that the Co–B nanoparticles were well dispersed on the Ni–B surface. Enlisted as a catalyst in the hydrolysis of ammonia borane (AB) for hydrogen generation (HG), the nanocomposite exhibited better catalytic activity than Co–B and Ni–B at room temperature; the HG rate was 1368.2 mL min −1 g −1 at 25 °C in a 1.5 wt.% AB solution, with a low activation energy of 33.5 kJ mol −1 . The effect of the complexing agent (sodium citrate) on the nanocomposite's catalytic activity was also investigated. In addition, recycling tests showed that Co–B/Ni–B was still highly active and preserved 84% of its initial catalytic activity after 11 recover-and-reuse cycles. [ABSTRACT FROM AUTHOR]

Abstract: BiFeO3 magnetic nanoparticles (BFO MNPs) are used as a catalyst to develop an ultrasensitive method for the determination of H2O2. It is found that BFO MNPs can catalyze the decomposition of H2O2 to produce ls, which in turn oxidize the weakly fluorescent benzoic acid to a strongly fluorescent hydroxylated product with a maximum emission at 405nm. This makes it possible to sensitively quantify traces of H2O2. Under optimized conditions, the fluorescence intensity is observed to be well linearly correlated with H2O2 concentration from 2.0×10−8 to 2.0×10−5 molL−1 with a detection limit of 4.5×10−9 molL−1 (S/N=3). In addition, a selective method for glucose determination is developed by using both glucose oxidase and BFO MNPs, which has a linear range for glucose concentration from 1.0×10−6 to 1.0×10−4 molL−1 with a detection limit of 5.0×10−7 molL−1. These new methods have been successfully applied for the determination of H2O2 in rainwater and glucose in human serum samples. [Copyright &y& Elsevier]

Abstract: Vitellin (Vt) and vitellogenin (Vg) profiles were analyzed in Pteromalus puparum, a pupal endoparasitoid of Pieris rapae. Non-denaturing and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) analyses indicated that both native Vt and Vg were likely 370kDa in size, consisting of two subunits of approximate 206 and 165kDa. An indirect double antibody enzyme-linked immunosorbent assay (ELISA) for monitoring hemolymph Vg and ovarian Vt levels was developed using a monoclonal antibody and a polyclonal antibody made specially against P. puparum Vt. The synthesis and uptake of Vg in this wasp was initiated immediately after adult eclosion. The hemolymph Vg and ovarian Vt reached their highest level of 0.58 and 4.51μg per female 24 and 48h after adult eclosion, respectively. Both Vg synthesis and uptake were in parallel with ovarian development. The Vt levels in the developing embryos decreased progressively except 12h after parasitism. Meanwhile, nine new polypeptides with sizes ranging from 59.2 to 151kDa, possibly resulting from the limited proteolysis of Vt originally accumulated in newly laid eggs, were detected de-novo during embryonic development using Western blotting with the monoclonal antibody against Vt. These studies provide the basis for future investigation into endocrinal regulations of vitellogenesis and understanding the reproductive strategy in this wasp. [Copyright &y& Elsevier]