Temperature dependence of narrow-band UVB photoluminescence of silica-(Gd,Pr)PO4transparent glass-ceramic phosphors.

The effect of temperature on photoluminescence (PL) due to the6Pj→8S7/2(j= 5/2, 7/2) transitions of Gd3+ions was examined between 200 and 500 K for a sol-gel-derived silica-(Gd,Pr)PO4transparent glass-ceramic phosphor with negligible concentration quenching under excitation into the 5d-4f transition of Pr3+ions at 220 nm. The intensity of the narrow-band ultraviolet B (UVB) PL at ∼313 nm associated with the6P7/2→8S7/2transition slightly increased between 200 and 300 K, but was decreased to ∼86% and ∼62% of that at 300 K when temperature was raised to 400 and 500 K, respectively. The observed magnitude of the thermal quenching of the UVB PL intensity was agreed well with that recorded in a prototype narrow-band UVB lamp consisting of another silica-(Gd,Pr)PO4transparent glass-ceramic window and a KrCl excimer lamp as a light source at 222 nm. The silica-(Gd,Pr)PO4transparent glass-ceramics was more resistant to the thermal quenching of the narrow-band UVB PL than a conventional powder phosphor, probably because of the encapsulation of (Gd,Pr)PO4nanocrystals with low quenching centre concentrations in inert silica glass matrix.

Synergistic effect of Ag decorated in-liquid plasma treated titanium dioxide catalyst for efficient electrocatalytic CO2 reduction application.

Recently, the conversion of carbon dioxide (CO2) into a useful resource and its byproducts by electrocatalytic reduction has been studied. It is well known that CO2 can be selectively reduced by gold, lead, etc. supported on conductive carbon. However, the high pH in the vicinity of the electrode raises concerns about the catalyst and catalyst support degradation. Therefore, we considered that using chemically stable TiO2 (titanium dioxide) powder as an alternative to carbon. Surface treatment using in-liquid plasma was used to improve the electrochemical properties of TiO2. TiO2 maintained its particle shape and crystalline structure after in-liquid plasma treatment. Electrochemical properties were evaluated and the disappearance of Ti4+ and Ti3+ redox peaks derived from TiO2 and a decrease in hydrogen overvoltage were observed. The hydrogen overvoltage relationship suggested that tungsten coating or doping on a portion of the reduced TiO2 surface. Electrocatalytic CO2 reduction using the silver nanoparticle-supported in-liquid plasma treated TiO2 showed increased hydrogen production. In electrocatalytic CO2 reduction, the ratio of hydrogen to carbon monoxide gas is important. Therefore, in-liquid plasma treated TiO2 is useful for the electrocatalytic CO2 reduction application.

Complete decomposition of sulfamethoxazole during an advanced oxidation process in a simple water treatment system.

A simple water treatment system consisting of a deep UV light (λ = 222 nm) source, a mesoporous TiO2/boron-doped diamond (BDD) photocatalyst, and a BDD electrode was prepared and used to decompose sulfamethoxazole (SMX) in an advanced oxidation process. The mesoporous TiO2/BDD photocatalyst used with the electrochemical treatment promoted SMX decomposition, but the mesoporous TiO2/BDD photocatalyst alone had a similar ability to decompose SMX as photolysis. Fragments produced through photocatalytic treatment were decomposed during the electrochemical treatment and fragments produced during the electrochemical treatment were decomposed during the photocatalytic treatment, so performing the electrochemical and photocatalytic treatments together effectively decomposed SMX and decrease the total organic carbon concentration to a trace.

Synergetic effect in water treatment with mesoporous TiO2/BDD hybrid electrode.

Boron-doped diamond (BDD) electrodes have a wide potential window and can produce ozone by water electrolysis at high voltage. Though ozone has strong oxidative power (standard oxidation potential: 2.07 V vs. NHE), it cannot decompose certain types of recalcitrant organic matter completely. We developed an advanced oxidation process (AOP), in which hydroxy radicals with stronger oxidative power (standard oxidation potential: 2.85 V vs. NHE) are formed using a combination of ozone, photocatalyst, and UV. In this study, we fabricated a mesoporous TiO2/BDD hybrid electrode and examined its potential for AOPs. A synergetic effect between electrochemical water treatment and photocatalytic water treatment was observed with the hybrid electrode that did not occur with the BDD electrode.

Synthesis of Mesoporous TiO2/Boron-Doped Diamond Photocatalyst and Its Photocatalytic Activity under Deep UV Light (λ = 222 nm) Irradiation.

There is a need for highly efficient photocatalysts, particularly for water purification. In this study, we fabricated a mesoporous TiO2 thin film on a boron-doped diamond (BDD) layer by a surfactant-assisted sol-gel method, in which self-assembled amphiphilic surfactant micelles were used as an organic template. Scanning electron microscopy revealed uniform mesopores, approximately 20 nm in diameter, that were hexagonally packed in the TiO2 thin film. Wide-angle X-ray diffraction and Raman spectroscopy clarified that the framework crystallized in the anatase phase. Current⁻voltage (I⁻V) measurements showed rectification features at the TiO2/BDD heterojunction, confirming that a p⁻n hetero-interface formed. The as-synthesized mesoporous TiO2/BDD worked well as a photocatalyst, even with a small volume of TiO2 (15 mm × 15 mm × c.a. 1.5 µm in thickness). The use of deep UV light (λ = 222 nm) as a light source was necessary to enhance photocatalytic activity, due to photo-excitation occurring in both BDD and TiO2.

Effect on surface character and mechanical property of unsintered hydroxyapatite/poly-l-lactic acid (uHA/PLLA) material by UV treatment.

Materials fabricated with unsintered hydroxyapatite/poly-l-lactic acid (uHA/PLLA) exhibit biological activity and biocompatibility, but are also hydrophobic. This hydrophobicity limits the ability of cells or tissues to adhere to the surface of the material and thereby prevents the materials from exhibiting effective biological activity. In this study, we examined the effects of ultraviolet (UV) treatment on the hydrophobicity of uHA/PLLA. We compared the contact angle, mechanical strength, cell attachment, and cell differentiation capacity between untreated uHA/PLLA and uHA/PLLA treated with UV light. The contact angle of UV-treated uHA/PLLA was significantly reduced compared with that of untreated uHA/PLLA. However, there were no differences in mechanical strength between untreated uHA/PLLA and UV-treated uHA/PLLA. Notably, the ability of cells to adhere to UV-treated uHA/PLLA was significantly increased compared with that of untreated uHA/PLLA. Similarly, there were significant differences between UV-treated uHA/PLLA and untreated uHA/PLLA in alkaline phosphatase assays. These findings demonstrated that UV irradiation of uHA/PLLA improved the surface hydrophilicity without changing the mechanical strength of the material; thus, UV treatment of uHA/PLLA may facilitate the use of this material in biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 191-200, 2018.

G-protein coupled estrogen receptor-mediated non-genomic facilitatory effect of estrogen on cooling-induced reduction of skin blood flow in mice.

An enhanced vasoconstrictor activity of cutaneous arteries participates in the reduction of skin blood flow induced by cooling stimulation. Raynaud's phenomenon, which is characterized by intense cooling-induced constriction of cutaneous arteries, is more common in women during the period from menarche to menopause. We thus investigated the effect of 17ß-estradiol (E2) on cooling-induced reduction of plantar skin blood flow (PSBF) in mouse in vivo. Ovariectomized female ddY mice, anaesthetized with pentobarbital, were treated with tetrodotoxin for eliminating the sympathetic nerve tone and artificially ventilated. The PSBF was measured by laser Doppler flowmetry. Cooling air temperature around the foot from 25 to 20, 15, or 10°C decreased the PSBF in a temperature-dependent manner, which was suppressed by the specific α2C-adrenoceptor antagonist MK-912. When E2 was intravenously administered as a bolus followed by a constant infusion for 10min just before the cooling stimulation, the cooling-induced reduction of PSBF was facilitated by E2 in a dose-dependent manner. The facilitatory effect of E2 was not induced after the treatment with MK-912. Similar facilitatory effect was induced by an intravenous application of G-1, an agonist of G protein-coupled estrogen receptor (GPER, also termed GPR30). Moreover, the facilitatory effect of E2 was abolished by the GPER antagonist G15. These results suggest that acute administration of E2 leads to the facilitation of cooling-induced, α2C-adrenoceptor-mediated reduction of skin blood flow via the activation of the non-genomic estrogen receptor GPER.

Boron-doped diamond semiconductor electrodes: Efficient photoelectrochemical CO2 reduction through surface modification.

Competitive hydrogen evolution and multiple proton-coupled electron transfer reactions limit photoelectrochemical CO2 reduction in aqueous electrolyte. Here, oxygen-terminated lightly boron-doped diamond (BDDL) thin films were synthesized as a semiconductor electron source to accelerate CO2 reduction. However, BDDL alone could not stabilize the intermediates of CO2 reduction, yielding a negligible amount of reduction products. Silver nanoparticles were then deposited on BDDL because of their selective electrochemical CO2 reduction ability. Excellent selectivity (estimated CO:H2 mass ratio of 318:1) and recyclability (stable for five cycles of 3 h each) for photoelectrochemical CO2 reduction were obtained for the optimum silver nanoparticle-modified BDDL electrode at -1.1 V vs. RHE under 222-nm irradiation. The high efficiency and stability of this catalyst are ascribed to the in situ photoactivation of the BDDL surface during the photoelectrochemical reaction. The present work reveals the potential of BDDL as a high-energy electron source for use with co-catalysts in photochemical conversion.