Cu/(Cu(OH)(2)-CuO) core/shell nanorods array: in-situ growth and application as an efficient 3D oxygen evolution anode

In this paper, we develop a novel strategy toward the in-situ growth of core/shell nanorods array consisting of Cu(OH)(2)-CuO nanosheets as the shell and Cu as the core on Cu foil [Cu/(Cu(OH)(2)-CuO) NA/CF]. As an integrated 3D non-noble-metal oxygen evolution anode, the Cu/(Cu(OH)(2)-CuO) NA/CF shows high catalytic activity with an onset overpotential of 350 mV and a Tafel slope of 76 mV/dec. It needs an overpotential of 417 mV to drive current density of 10 mA/cm(2) and maintains its catalytic activity for at least 22 h. The attractive performances make it promising candidate as a future high-performance catalyst for applications. (C) 2015 Elsevier Ltd. All rights reserved

Uranyl Carboxyphosphonates Derived from Hydrothermal in Situ Ligand Reaction: Syntheses, Structures, and Computational Investigations

wo uranyl carboxyphosphonates (H(2)dipy)[UO2)(3) (H2O)(2) (H2PPTP)(2)]center dot 2H(2)O (DPTP-U1) and (H(2)bbi)[(UO2)(4)(H2O)(2)(HDPTP)(2)] (DPTP-U2) [H6DPTP = 2,5diphosphonoterephthalic acid, dipy = 4,4'-bipyridine, bbi = 1,1'-(1,4-butanediyObis(imidazole)] were synthesized under hydrothermal conditions. The carboxyphosphonate ligand was formed through the in situ oxidation of (2,5-dimethy1-1,4phenylene)diphosphonic acid mediated by UO22+. Single-crystal X-ray diffraction analyses reveal that DPTP-U1 possesses uranyl carboxyphosphonate layers that are separated by protonated dipy cations. Whereas DPTP-U2 is in a three-dimensional framework structure with channels filled by protonated bbi cations. The computational investigations give an insight into the nature of bonding interactions between uranium(VI) and carboxyphosphonate ligand. The spectroscopic properties were also studied

Simultaneous Control over both Molecular Order and Long-Range Alignment in Films of the Donor-Acceptor Copolymer

Control over both molecular order and long-range alignment order in films of the donor-acceptor copolymer of 3,6-bis(thiophen-2-yl)-N,N'-bis(2-octyl-1-dodecyl)-1,4-dioxo-pyrrolo[3,4-c]pyrrole and thieno[3,2-b]thiophene (PDBT-TT) was demonstrated via off-center spin-coating (OCSC) from its blend solution with polystyrene (PS). It was found that the dichroic ratio (DR) of OCSC blend films was dependent on both the physical process of spin-coating and the effect of PS chains. The highest DR of 2.75 was obtained via OCSC from the blend solution in oDCB at 1500 rpm. Meanwhile, both the intrachain and interchain molecular order were improved in blend films compared with neat ones, which were indicated by the red-shift of the max absorption, enhanced J-aggregation absorption, and smaller pi-pi stacking distance (from 3.77 to 3.70 angstrom). According to the results of the investigation into the macro anisotropy, micro morphology, solution rheology properties, and photophysics features of films, an overall mechanism of simultaneous control over molecular and long-range order of D-A copolymer films was proposed. On the one hand, a larger viscosity and the pseudoplastic nature of the solution tuned by choosing good solvents with high boiling points and adding PS resulted in a better chain disentanglement, better shear transfer, and a slower contact line receding velocity to induce an enhanced alignment of chains and thus fibrillar aggregates. Also, the critical contact line receding velocity for alignment dominated by the solvent evaporation rate accounted for the variation of DR with OCSC rates. A vertical phase separation accompanying the formation of aligned fibrils during OCSC was also confirmed due to the friction shear between air and solution surface. On the other hand, the negligible dependence of the blend OCSC films photophysical and morphological features on the solvent suggested the critical role of PS in determining the better intrachain conjugation in blend films, which was attributed to multiple reasons, like limited phase separation room, a coil-toward conformation promotion, and a high surface energy. Furthermore, the enhanced pi-attraction and smaller steric hindrance induced by improved intrachain conjugation accounted for the smaller pi-pi stacking distance in the blend films than that in the neat ones

Investigations on structures, thermal expansion and electrochemical properties of La0.75Sr0.25Cu0.5-xCoxMn0.5O3-delta (x=0, 0.25, and 0.5) as potential cathodes for intermediate temperature solid oxide fuel cells

A series of perovskite oxides have been investigated as excellent potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this paper, we take the La0.75Sr0.25Cu0.5-xCoxMn0.5O3-delta (LSCCM, x = 0, 0.25 and 0.5) system as subject, with Cu/Mn and/or Co/Mn on B-site and 25% Sr-substituted La ions on A-site, to investigate their structures, thermal stability and electrochemical properties. Pure rhombohedral crystal with space group R (3) over barc (no. 167) is identified by Rietveld refinement of X-ray diffraction data (XRD). It is found that the thermal expansion coefficient (TEC) is manageable when Co ion is incorporated, and the low TEC value ranges from 12.7 x 10(-6) to 15.4 x 10(-6) K-1 that are well compatible with prototypical electrolytes Zr0.84Y0.16O1.92 (YSZ) and Ce0.8Sm0.2O2-delta (SDC). The dc-conductivity is significantly enhanced from 36.5, 90.5 to 173.7 S cm(-1) at 850 degrees C with the increasing Co percent, and accordingly, polarization resistance (R-p) is determined as 0.1291, 0.0835 and 0.0486 V cm(2) at 800 degrees C. The high electrical conductivities and low resistances can be attributed to the strong B-O bond hybridization and oxygen vacancy formation at elevated temperatures with the introduction of Co ion, which is consistent with the results of first-principles calculation and thermogravimetric analysis. All these results demonstrate that LSCCM series are promising cathodes with controllable TEC for IT-SOFCs. (C) 2015 Elsevier Ltd. All rights reserved

电感耦合等离子体质谱法测定磷酸钡激光玻璃中超痕量铜

将高纯HF-HNO3组合试剂与高纯PFA低压密闭消解罐建立了针对目标高温烧结体的简洁、快速、低本底湿法样品处理流程。系统优化了组合消解试剂的用量和配比、样品消解温度和消解时间等因素,实现了在150益消解温度时1.7 m L的总试剂消耗量下样品完全分解总耗时小于1 h,且无需对样品破碎至细颗粒,大大降低了样品制备中的玷污风险。以水杨醛肟类作萃取剂,建立了高效液液萃取分离富集法。以5 m L15%的萃取剂浓度在0.5%HNO3的萃取酸度和20%HNO3反萃取酸浓度下,实现了99.999%的基体分离效率,Cu2+富集10倍。优化了电感耦合等离子体质谱(ICP-MS)测定参数,在840 W低功率和低样品提取量时实现20%HNO3酸度下铜的高信背比检测,全流程方法检出限2.5 ng/g,平行测定RSD(n=6)为3.3%,加标回收率94.3%。基于所建立的方法实现了实际样品的准确测定,得出铜含量与激光能量衰减实验结果线性相关的结果

A facile method for the sensing of antioxidants based on the redox transformation of polyaniline

Polyaniline (PANI) is one of the most studied conducting polymers. It could adopt a number of chemical forms depending on the redox states of the assay solution. It was observed that the emeraldine base form of PANI could be reduced by common antioxidants (such as glutathione and ascorbic acid), which resulted in clear changes of the solution color and the UV-vis absorption spectra. In addition, it was observed that the fluorescence of CdTe quantum dots could be efficiently quenched by PANI, and the fluorescence quenching could not take place by the addition of antioxidants. The intensity of the quantum dots fluorescence could be directly related to the amount of antioxidant added to the assay solution, thus a sensitive fluorescent turn-on sensor for antioxidant was established. The detection limits for glutathione and ascorbic acid were estimated to be 50 nM and 100 nM, respectively. Our assay is simple, sensitive, and label-free, we envision it could facilitate the antioxidant sensing related applications. (C) 2014 Elsevier B.V. All rights reserved

Effect of grafted PEG chain conformation on albumin and lysozyme adsorption: A combined study using QCM-D and DPI

In this study, elucidation of protein adsorption mechanism is performed using dual polarization interferometry (DPI) and quartz crystal microbalance with dissipation (QCM-D) to study adsorption behaviors of bovine serum albumin (BSA) and lysozyme (LYZ) on poly (ethylene glycol) (PEG) layers. From the analysis of DPI, PEG2000 and PEG5000 show tight and loose mushroom conformations, respectively. Small amount of LYZ could displace the interfacial water surrounding the tight mushroomed PEG2000 chains by hydrogen bond attraction, leading to protein adsorption. The loose mushroomed PEG5000 chains exhibit a more flexible conformation and high elastic repulsion energy that could prevent protein adsorption of all BSA and most of LYZ. From the analysis of QCM, PEG2000 and PEG5000 show tight and extended brush conformations. The LYZ adsorbed mass has critical regions of PEG2000 (0.19 chain/nm(2)) and PEG5000 (0.16 chain/nm(2)) graft density. When graft density of PEG is higher than the critical region (brush conformations), the attraction of hydrogen bonds between PEG and LYZ is the dominant factor. When graft density of PEG is lower than the critical region (mushroom conformations), elastic repulsion between PEG and proteins is driven by the high conformation entropy of PEG chains, which is the dominant force of steric repulsion in PEG-protein systems. Therefore, the adsorption of BSA is suppressed by the high elastic repulsion energy of PEG chains, whereas the adsorption of LYZ is balanced by the interactions between the repulsion of entropy elasticity and the attraction of hydrogen bonds. (C) 2015 Elsevier B.V. All rights reserved

Mesoscale morphology evolution of a GdAl3(BO3)(4) single crystal in a flux system: a case study of thermodynamic control of the anisotropic mass transfer during crystal growth

In the flux system of GdAl3(BO3)(4), the compromise in competition between thermodynamic and kinetic control on the mass transfer has been studied from the viewpoint of chemical engineering. Different control mechanisms on the mass transfer in the melt growth system result in various mesoscale morphologies of a single crystal. Both the calculated and experimental results demonstrate thermodynamic control of the anisotropic mass transfer during crystal growth, leading to the mesoscale morphology evolution of the GdAl3(BO3)(4) single crystal similar to the matryoshka. The present work can deepen our understanding of mesoscale morphology evolution of the GdAl3(BO3)(4) single crystal in the flux growth system

Particle-size dependent melt viscosity behavior and the properties of three-arm star polystyrene-Fe3O4 composites

The melt viscosity of three-arm star polystyrene (S3PS)-Fe3O4 nanoparticle composites was studied by means of rheological measurements. The arm molecular weight (M-a) of S3PS (or radius gyration) and the particle size of Fe3O4 (radius (R-p): 3 nm and 44 nm) showed a strong influence on the melt viscosity behavior (at low shear frequencies) of S3PS-Fe3O4 composites. The reinforcement (viscosity increase) was observed in the composites where the Ma was higher than the M-c of PS (M-c: the critical molecular weight for chain entanglement). For M-a < M-c, when the size of Fe3O4 nanoparticles was changed, the melt viscosity of the composites exhibited either plasticization (melt viscosity reduction) or reinforcement. When the content of Fe3O4 was low (1 wt%), the transformation from plasticization to reinforcement behavior could be observed, which strongly depended on the size ratio of the radius of gyration (R-g) of S3PS to the size of nanoparticles (Rp). In addition, the magnetic properties and thermal stability of S3PS-Fe3O4 composites were studied