394 research outputs found

    Treatment time for non-surgical endodontic therapy with or without a magnifying loupe

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    Synthesis, Magnetic Anisotropy and Optical Properties of Preferred Oriented Zinc Ferrite Nanowire Arrays

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    Preferred oriented ZnFe2O4 nanowire arrays with an average diameter of 16 nm were fabricated by post-annealing of ZnFe2 nanowires within anodic aluminum oxide templates in atmosphere. Selected area electron diffraction and X-ray diffraction exhibit that the nanowires are in cubic spinel-type structure with a [110] preferred crystallite orientation. Magnetic measurement indicates that the as-prepared ZnFe2O4 nanowire arrays reveal uniaxial magnetic anisotropy, and the easy magnetization direction is parallel to the axis of nanowire. The optical properties show the ZnFe2O4 nanowire arrays give out 370–520 nm blue-violet light, and their UV absorption edge is around 700 nm. The estimated values of direct and indirect band gaps for the nanowires are 2.23 and 1.73 eV, respectively

    Capture barrier of Sn-related DX centers in AlGaAs epilayers

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    Thermal capture and emission processes of Sn-related DX centers in AlxGa1-xAs (x = 0.26) were measured by a constant capacitance (CC) voltage transient in various temperatures, By employing a Laplace defect spectroscopic (LDS) method, the non-exponential transients were decomposed into several discrete exponential components. The results shown that more exponential components appeared in the small emission rate region as capture period increased. This indicates that electrons preferentially fill shallow energy levels due to their lower capture barriers. Discrete exponential components of the capture process were identified and four of their barriers were preliminarily measured to be about 0.14, 0.15, 0.16, and 0.17 eV, respectively

    Heterogeneous electrocatalytic reduction of maleic acid on nanocrystalline TiO2 film modified Ti electrode

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    The precursor Ti(OEt)(4) was prepared by anodic dissolution of metallic titanium in absolute ethanol and direct hydrolysis to prepare nanocrystalline TiO2 film on titanium electrode (Ti/nano-TiO2) by a sol-gel process. SEM and XRD were used to characterize the structure of nanocrystalline TiO2 film (anatase, 25 nm). Redox behavior and electrocatalytic activities of the Ti/nano-TiO2 electrode were investigated by cyclic voltammetry (CV) and cyclic osteryoung square wave voltammetry (COV) and bulk electrolysis. The results indicate that there are two pairs of well-defined redox peaks for Ti/nano-TiO2 film electrode in 1 mol/L H2SO4 with E-1/2(r) of -0.53 V and -0.92 V (vs. SCE) at 0.05 V (.) s(-1) in correspondence with TiO2/Ti2O3 and TiO2/Ti(OH)(3) reversible electrode process and the heterogeneous electrocatalytic reduction activities of TiO2/Ti2O3 redox in the electrode for maleic acid. It is found that the indirect electroreduction of maleic acid to butane diacid was achieved by Ti-IV/Ti-III redox system on the nanocrystalline TiO2 film surface, the electrode reaction mechanism is the called catalytic (EC') mechanism

    Electrochemical synthesis of zinc complexes and preparation of nano-sized ZnO

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    Zinc complexes were directly prepared by using zinc metal as sacrificing anode in a cell without separating the cathode and anode spaces. The products were characterized by using FT-IR, NMR and Raman spectroscopy. The influence of temperature and conductive additives on product yield was also investigated. The study shows that direct electrochemical preparation of zinc complexes such as Zn(acac)(2), Zn(OEt)(2) (acac)(2) and Zn(OBu)(2)(acac)(2) has high current efficiency and electrolysis yield than that of Zn(OR)(2). Furthermore, these zinc complexes have high purity and can be directly used as sol-gel precursor for preparation of nanometer ZnO. Experimental results show that controlling temperature in the range of 50 similar to 60 degreesC, selecting R4NBr as conductive additives and preventing zinc anode from being covered by electrochemical products can improve product yield. The study also shows that nano-sized ZnO prepared by this method has monoclinic structure with a narrow size distribution of 5-10 nm

    TRIM16 Acts as an E3 Ubiquitin Ligase and Can Heterodimerize with Other TRIM Family Members

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    The TRIM family of proteins is distinguished by its tripartite motif (TRIM). Typically, TRIM proteins contain a RING finger domain, one or two B-box domains, a coiled-coil domain and the more variable C-terminal domains. TRIM16 does not have a RING domain but does harbour two B-box domains. Here we showed that TRIM16 homodimerized through its coiled-coil domain and heterodimerized with other TRIM family members; TRIM24, Promyelocytic leukaemia (PML) protein and Midline-1 (MID1). Although, TRIM16 has no classic RING domain, three-dimensional modelling of TRIM16 suggested that its B-box domains adopts RING-like folds leading to the hypothesis that TRIM16 acts as an ubiquitin ligase. Consistent with this hypothesis, we demonstrated that TRIM16, devoid of a classical RING domain had auto-polyubiquitination activity and acted as an E3 ubiquitin ligase in vivo and in vitro assays. Thus via its unique structure, TRIM16 possesses both heterodimerization function with other TRIM proteins and also has E3 ubiquitin ligase activity

    Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

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    The decay channel ψπ+πJ/ψ(J/ψγppˉ)\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) is studied using a sample of 1.06×1081.06\times 10^8 ψ\psi^\prime events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the ppˉp\bar{p} invariant mass spectrum. The enhancement can be fit with an SS-wave Breit-Wigner resonance function with a resulting peak mass of M=186113+6(stat)26+7(syst)MeV/c2M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2 and a narrow width that is Γ<38MeV/c2\Gamma<38 {\rm MeV/}c^2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

    Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation

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    <p>Abstract</p> <p>Background</p> <p>The Wnt/β-catenin pathway is a major signaling cascade in bone biology, playing a key role in bone development and remodeling. The objectives of this study were firstly, to determine the effects of dexamethasone exposure on Wnt/β-catenin signaling at an intracellular and transcriptional level, and secondly, to assess the phenotypic effects of silencing the Wnt antagonist, Dickkopf-1 (Dkk1) in the setting of dexamethasone exposure.</p> <p>Methods</p> <p>Primary human osteoblasts were exposed in vitro to 10<sup>-8 </sup>M dexamethasone over a 72 h time course. The phenotypic marker of osteoblast differentiation was analyzed was alkaline phosphatase activity. Intracellular β-catenin trafficking was assessed using immunoflourescence staining and TCF/LEF mediated transcription was analyzed using a Wnt luciferase reporter assay. Dkk1 expression was silenced using small interfering RNA (siRNA).</p> <p>Results</p> <p>Primary human osteoblasts exposed to dexamethasone displayed a significant reductions in alkaline phosphatase activity over a 72 h time course. Immunoflourescence analaysis of β-catenin localization demonstrated a significant reduction in intracytosolic and intranuclear β-catenin in response to dexamethasone exposure. These changes were associated with a reduction of TCF/LEF mediated transcription. Silencing Dkk1 expression in primary human osteoblasts exposed to dexamethasone resulted in an increase in alkaline phosphatase activity when compared to scrambled control.</p> <p>Conclusions</p> <p>Wnt/β-catenin signaling plays a key role in regulating glucocorticoid-induced osteoporosis <it>in vitro</it>. Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation. Targeting of the Wnt/β-catenin signaling pathway offers an exciting opportunity to develop novel anabolic bone agents to treat osteoporosis and disorders of bone mass.</p

    Oxidation behavior of graphene-coated copper at intrinsic graphene defects of different origins

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    The development of ultrathin barrier films is vital to the advanced semiconductor industry. Graphene appears to hold promise as a protective coating; however, the polycrystalline and defective nature of engineered graphene hinders its practical applications. Here, we investigate the oxidation behavior of graphene-coated Cu foils at intrinsic graphene defects of different origins. Macro-scale information regarding the spatial distribution and oxidation resistance of various graphene defects is readily obtained using optical and electron microscopies after the hot-plate annealing. The controlled oxidation experiments reveal that the degree of structural deficiency is strongly dependent on the origins of the structural defects, the crystallographic orientations of the underlying Cu grains, the growth conditions of graphene, and the kinetics of the graphene growth. The obtained experimental and theoretical results show that oxygen radicals, decomposed from water molecules in ambient air, are effectively inverted at Stone-Wales defects into the graphene/Cu interface with the assistance of facilitators
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