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Gold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300 °C to 525 °C with 2 °C/h rate and 25 °C step under 50 MPa. Pyrolysis temperature of 425 °C is critical for weight loss of bulk bitumen and hydrocarbon generation and destruction. Polar compounds are the main source of saturated and aromatic hydrocarbon, gas and coke fractions. Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures. High molecular weight n-alkanes (C26+) are gradually destructed during pyrolysis due to thermal cracking. Moderate molecular weight n-alkanes (C21–C25) show the highest thermal stability in designed pyrolysis temperatures. The loss of low molecular weight n-alkanes (C20−) might be caused by volatilization during pyrolysis, which may alter commonly used molecular parameters such as ∑n-C20−/∑n-C21+, Pr/n-C17 and Ph/n-C18. Aromatic hydrocarbons were generated from 300 to 425 °C, then condensation and dealkylation have been initiated at 425 °C as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures. The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin, while fluoranthene shows unexpected behaviors during pyrolysis. Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples. [ABSTRACT FROM AUTHOR]

Abstract: Two pyrazolate-bridged dinuclear Pd(II) diimine complexes {[(phen)Pd]2L2}(NO3)2 (1) and {[(bpy)Pd]2L2}(NO3)2 (2) have been synthesized through metal–metal interaction and spontaneous deprotonation from 1H-3,5-diphenylpyrazole (HL) in aqueous solution. These complexes show Pd(II)⋯Pd(II) interactions and anion binding have been characterized by elemental analyses, 1H and 13C NMR, ESI-MS, UV–Vis and luminescent spectroscopy, and single crystal X-ray diffraction methods. [Copyright &y& Elsevier]

In the crystal structure of the title compound, [Pd2(C22H17N2)2(C12H12N2)2](PF6)2·C4H10O·H2O, two Pd(dmbpy) units (dmbpy is 4,4′-dimethyl-2,2′-bipyridine) are bridged by 4-benzyl-3,5-diphenylpyrazolate ligands in an exodentate fashion, which results in a clip-like cavity between the two Pd(dmbpy)Pd planes. A disordered hexafluoridophosphate anion is held in the cavity by an anion–π interaction [P—F... Cg1 = 3.435 (15) Å ( Cg1 is the centroid of the Pd–dmbpy chelate ring system) and P—F... Cg2 = 3.187 (15) Å ( Cg2 is the centroid of a pyridine ring)]. A crystallographic twofold rotation axis passes through an F atom of the disordered anion and the mid-point of the two Pd atoms. The P and two F atoms of the second anion also lie on a twofold rotation axis, as do the O atom of the diethyl ether and the water O atom. The crystal structure is stabilized by electrostatic forces between the cations and anions, and intermolecular hydrogen bonds involving hexafluoridophosphate anions (C—H...F), the solvent diethyl ether molecules and water molecules (C—H...O). [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnO/TiO 2 heterojunction was constructed, effectively separating photo-generated carriers. • ZnO should be electrodeposited by CV on high crystallinity TiO 2 nanorods that have been calcined. • Depositing ZnO facilitates rapid electron transfer. • Introducing oxygen-rich vacancy ZnO effectively enhances the photocatalytic performance of TiO 2 photoanode. This study presents a novel approach utilizing a simple, stable, reproducible CV (Cyclic Voltammetry) electrodeposition method to deposit varying amounts of ZnO onto ordered TiO 2 (Rutile) nanorod arrays. Comprehensive investigations were conducted on the morphology, semiconductor band-gap structure of different ZnO/Rutile composites, and their performance in photocatalytic (PC) and photoelectrochemical (PEC) hydrogen production. Results demonstrate that the ZnO/TiO 2 photoanodes fabricated in this manner exhibit outstanding PC/PEC hydrogen production capabilities. Particularly noteworthy is the Z/R-15 photoanode, showcasing superior PEC performance with a photocurrent density 3.5 times higher than that of the pristine TiO 2 photoanode under equivalent conditions. Furthermore, it was observed that depositing ZnO onto highly crystalline, annealed TiO 2 nanorods yields optimal photoelectrical properties. Incorporating oxygen-rich vacancies in ZnO significantly enhances the photoelectrocatalytic performance of TiO 2 photoanodes. The CV electrodeposition method offers valuable insights for developing efficient photocatalytic hydrogen production catalysts. [ABSTRACT FROM AUTHOR]

Nowadays, anyone carrying a mobile device can enjoy the various location-based services provided by the Internet of Things (IoT). 'Aggregate nearest neighbor query' is a new type of location-based query which asks the question, 'what is the best location for a given group of people to gather?' There are numerous, promising applications for this type of query, but it needs to be done in a secure and private way. Therefore, a trajectory privacy-preserving scheme, based on a trusted anonymous server (TAS) is proposed. Specifically, in the snapshot queries, the TAS generates a group request that satisfies the spatial K-anonymity for the group of users—to prevent the location-based service provider (LSP) from an inference attack—and in continuous queries, the TAS determines whether the group request needs to be resent by detecting whether the users will leave their secure areas, so as to reduce the probability that the LSP reconstructs the users' real trajectories. Furthermore, an aggregate nearest neighbor query algorithm based on strategy optimization, is adopted, to minimize the overhead of the LSP. The response speed of the results is improved by narrowing the search scope of the points of interest (POIs) and speeding up the prune of the non-nearest neighbors. The security analysis and simulation results demonstrated that our proposed scheme could protect the users' location and trajectory privacy, and the response speed and communication overhead of the service, were superior to other peer algorithms, both in the snapshot and continuous queries. [ABSTRACT FROM AUTHOR]

Three chain-based GdIII coordination polymers, namely [Gd2(SO4)3(phen)2(H2O)2]n (1), [Gd2(oda)2(ox)(H2O)6]n (2) and {[Gd2(glu)3(H2O)2]·4H2O}n (3) (phen = 1,10-phenanthroline, H2oda = oxydiacetic acid, H2ox = oxalic acid and H2glu = glutaric acid), have been successfully constructed by using multidentate O ligands under hydro/solvothermal conditions. Complex 1 has a one-dimensional (1D) chain bridged by inorganic sulfate, and complex 2 exhibits a 1D double-chain ladder-shaped structure connected by oxalate. While, complex 3 is a three-dimensional (3D) metal–organic framework composed of 1D chains. All of them display good thermal stabilities and large magnetic entropy changes with −ΔSmaxm ＞ 31 J kg−1 K−1 (7 T), suggesting them to be good candidates for use as cryogenic magnetic refrigerants. [ABSTRACT FROM AUTHOR]

Abstract: A novel graphene oxide sheets/polyaniline/CdSe quantum dots (GO/PANi/CdSe) nanocomposites were successfully synthesized and used for the sensitive electrochemiluminescence (ECL) biosensing. The GO/PANi/CdSe nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet–visible (UV–vis) absorption spectroscopy, photoluminescence (PL) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Finally, the nanocomposites were employed to construct the biosensor via layer-by-layer assembly for the ECL detection of Cytochrome C (Cyt C). The whole process was characterized by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). Experimental parameters such as the ratio of GO/PANi, the K2S4O8 concentration and the pH value of electrolyte solution were studied to investigate the effect on the ECL intensity. Under the optimized conditions, the ECL intensity decreased linearly with the Cyt C concentrations in the range from 5.0×10−8 to 1.0×10−4 M with detection limit of 2.0×10−8 M. Besides, the as-proposed biosensor exhibits high specificity, good reproducibility, and stability, and may be applied in more bioanalytical systems. [Copyright &y& Elsevier]