We report the fabrication and electroluminescence of a simple ZnO nanotube diode. The hexagonal ZnO nanotubes are synthesized electrochemically using a two-step method. At low forward bias, the electroluminescence spectrum of the ZnO nanotube diode exhibits a traditional emission spectrum composed of an excitonic peak centered at 400 nm and a broad-band emission at around 550 nm, consistent with its photoluminescence spectrum. When a higher voltage is applied, the diode current grows rapidly and the spectral coverage broadens to include almost the entire visible spectrum. The electroluminescent intensity of the ZnO nanotube diode is much stronger than that of the ZnO nanorod diode

A novel method of ultraviolet vapour generation (UVG) coupled with atomic fluorescence spectrometry (AFS) was developed for the determination of ultratrace inorganic arsenic (iAs) in surface water. In this work, different ferric species were utilised for the first time as an enhancement reagent for the ultraviolet vapour generation of As(III), and their UVG efficiencies for volatile species of arsenic were investigated. 15 mg L(-1) of ferric chloride provided the greatest enhancement of approximately 10-fold, using 20% acetic acid combined with 4% formic acid with 30 s ultraviolet irradiation at 200 mL min(-1) Ar/H2 flow rate. Under the optimised conditions, the linear range was 1.0 μg L(-1)-100.0 μg L(-1), and the spiked recoveries were 92%-98%. The limit of detection was 0.05 μg L(-1) for iAs, and the relative standard deviation (RSD) value of the repeated measurements was 2.0% (n = 11). This method was successfully applied to the determination of ultratrace iAs in tap water, river water, and lake water samples using 0.2% H2SO4 (v : v) as the sample preserver. The obtained values for the water samples of certified reference materials (CRMs) including GSB-Z50004-200431, GBW08605 and GBW(E)080390 were all within the certified ranges.

ObjectiveDifficulty in wound healing is one common complication of diabetes mellitus. The study explored whether the therapeutic effect of human umbilical cord mesenchymal stem cells (hUCMSCs) on diabetic ulcer wound was enhanced by the activation of the Wnt signaling pathway.MethodsRat diabetic model was established by intraperitoneal injection of Streptozotocin (STZ). hUCMSCs were purified and seeded on the collagen–chitosan laser drilling acellular dermal matrix (CCLDADM) scaffold, which was subsequently implanted into the cutaneous wound of normal and diabetic rats, followed by daily injection of Wnt signaling pathway agonist (Wnt3a) or antagonist (sFRP3) at the edge of the scaffold. Wound healing was checked on days 7, 14, and 21, and the fibrous tissue deposition, capillaries, and epidermal regeneration at the wound were examined by hematoxylin–eosin staining. The hUCMSCs-CCLDADM scaffold was cultured in vitro and treated with Wnt3a or sFRP3, followed by evaluation of cell proliferation, cell proliferation rate, survival status, and altered protein levels in the Wnt signaling pathway using BrdU staining, CCK-8 assay, live/dead staining, and Western blotting, respectively.ResultsOn days 7 and 14 postoperatively, the speed of wound healing was significantly lower in diabetic rats than that in normal control rats. This phenomenon was significantly improved by the activation of the Wnt signaling pathway that also elevated the fibrous protein deposition and the abundance of capillary in the granulation tissue. Conversely, blockade of Wnt signaling slowed the healing of skin wound in diabetic rats. The activation of Wnt signaling pathway promoted the proliferation and differentiation and decreased the apoptosis of hUCMSCs, thereby elevating the number of living hUCMSCs on the CCLDADM scaffold, while the suppression exerted a contrary effect.ConclusionThe activation of the Wnt signaling pathway promotes the healing of diabetic skin wound by the regulation of proliferation and differentiation of hUCMSCs on the CCLDADM scaffold.

By contrast with the rich, wurztite-related, one-dimensional nanostructure of ZnO and its wide variety of applications, there only exists a few methods for the controlled and designed synthesis of one-dimensional CdSe nanostructures. Here, we describe a low-temperature and directed preparation of CdSe nanowires in a simple one-step, template-free electrochemical deposition. The preparation takes advantage of both the wurtzite structure characteristics and current-induced preferential orientation. High-resolution transmission electron microscopy (TEM) images and selected area electron diffraction (SAED) patterns clearly verify that the prepared CdSe nanowires have a single-crystal wurtzite structure and grow along the [0001] (c-axis). With the discovery of other one-dimensional CdSe nanostructures and CdS nanowires, it is anticipated that this electrochemical synthesis method can be extended to other nanostructures of CdSe and to other II−VI semiconductors and can also be developed into a systematic synthesis for nanostructured semiconductors. The average diameter of the thus prepared CdSe nanowires is larger than those synthesized by chemical vapor deposition (CVD) and solution−liquid−solid (SLS) methods. This may be an advantage in some applications, for example, as the light-harvesting material in photovoltaic cells. Organic/inorganic hybrid photovoltaic cells fabricated with CdSe nanowires and PEDOT:PSS give a good photovoltaic performance, demonstrating the attractive potential of CdSe nanowire applications in photovoltaics.

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The most common approximation of electroneutrality is inappropriate for analyzing the voltammetric response of nanoelectrodes. Therefore, the microelectrode theory for extracting the standard rate constant k 0 for electron transfer from steady-state voltammograms is invalid for nanoelectrodes. Unlike previous approaches, we considered the influence of the interfacial potential distribution caused by the absence of electroneutrality. We estimated the magnitude of the error at low overpotential incurred as a result of ignoring the absence of electroneutrality and found that it was small. In this region, electrochemical reaction appears to be limited by the rate of electron transfer. Under these conditions, k 0 can be obtained from steady-state voltammogram data in a low overpotential region according to an approximate form of the Butler -Volmer equation. This procedure can greatly simplify analysis and calculation of the rate constant k 0 at nanoelectrodes.