Visible Light Irradiation Time Research Articles

Iodine-doped carbon dots with inherent peroxidase catalytic activity for photocatalytic antibacterial and wound disinfection.

A new type of nitrogen-iodine co-doped carbon dot (N/I-CD) was synthesized by a one-step hydrothermal method with a fluorescence quantum yield of 37%. The prepared N/I-CDs exhibit peroxidase-like activity, can catalyze bio-safety levels of H2O2 to generate hydroxyl radicals (•OH) under visible light and enhance the level of reactive oxygen species (ROS) in bacteria cells. All in vitro experiments showed that the designed system has strong photocatalytic antibacterial activity against both E. coli and S. aureus bacteria. The light-induced antibacterial function of N/I-CDs was evaluated under the conditions of changing other experimental parameters. When the visible light irradiation time was extended to 60min, the antibacterial efficiency of N/I-CDs (0.21mg·mL-1) against S. aureus and E. coli reached 100% in the presence of exogenous H2O2 (0.07mM). More importantly, wound disinfection in vivo demonstrates the high antibacterial efficiency, low toxicity and application potential of good biocompatibility due to the nanozyme activity of N/I-CDs.

Highly efficient visible-light driven photocatalytic hydrogen production over (MoSe2-RGO)/(Er3+:Y3Al5O12/ZnS)/RuO2 photocatalyst

The use of co-catalysts can observably enhance photocatalytic hydrogen production activity. In this work, a novel visible-light driven photocatalyst, (MoSe2-RGO)/(Er3+:Y3Al5O12/ZnS)/RuO2 nanocomposite, is prepared for the first time by loading Er3+:Y3Al5O12, MoSe2-RGO and RuO2 on the surface of ZnS nanoparticles. Er3+:Y3Al5O12 as an effective visible-to-ultraviolet up-conversion luminescence agent can provide the ultraviolet-light to activate wide band-gap ZnS. MoSe2-RGO and RuO2, acting as conduction band co-catalyst and valence band co-catalyst, respectively, can effectively separate the photo-generated carriers and supply more reactive sites. The activities of the photocatalysts were assessed via photocatalytic hydrogen production in Na2S and Na2SO3 aqueous solution under 300 W xenon lamp irradiation. In addition, the visible-light irradiation time and used times of the prepared samples as influence factors on the photocatalytic hydrogen production were also investigated. It was easily found that the prepared (MoSe2-RGO)/(Er3+:Y3Al5O12/ZnS)/RuO2 nanocomposite shows fairly high activity in photocatalytic hydrogen production, compared with single ZnS photocatalyst. It was mainly attributed to the excellent up-conversion luminescence property of Er3+:Y3Al5O12 and the efficient separation of photo-generated electrons and holes caused by MoSe2-RGO and RuO2. This research may pave an effective way for photocatalytic hydrogen production utilizing solar light.

Preparation of a AgCl/PbMoO4 Composite and Investigation of Its Photocatalytic Oxidative Desulfurization Performance.

PbMoO4 materials were synthesized by the glycerol and hydrothermal methods, and AgCl nanoparticles were loaded onto the surface of PbMoO4 by using the precipitation–deposition method. Finally, a AgCl/PbMoO4 photocatalyst was successfully prepared. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy (UV–vis-DRS) were used to characterize the phase composition, morphology, and light absorption characteristics of the catalyst. An n-octane solution of dibenzothiophene (DBT) was used to simulate fluid catalytic cracking to make gasoline. The photocatalytic oxidation performance of DBT under visible light was studied in terms of the type of light source as well as of the catalyst, substrate, and AgCl content. The mechanism of photocatalytic oxidation was also studied. The results show that AgCl loading causes a red shift of the absorption edge of PbMoO4, which improves the photocatalytic activity of the material. When the AgCl loading was 25.0%, the amount of catalyst was 1.5 g/L, and the visible light irradiation time was 2.0 h, the highest desulfurization rate of DBT reached 97.0%.

A comprehensive study on the enhanced photocatalytic activity of Cu2O/BiVO4/WO3 nanoparticles

A ternary Cu2O-BiVO4-WO3 nano-composite was prepared and its catalytic activity was evaluated in the photodegradation of sulfasalazine (SSZ). The structural and compositional characterization of the composite was evaluated by XRD, TEM, and FE-SEM techniques. Its optical properties were also investigated by UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The composite showed a boosted activity with respect to the individual semiconductors due to better charge carriers' separation. The increased charge separation of the composite was confirmed by the PL results. The composite showed weaker PL peaks than the single systems, showing slower e−/h+ recombination. Both PL intensity and photodegradation efficiency depended on the mole ratio of the combined semiconductors in the composite. The mole ratio of 2:1:1 for the Cu2O/BiVO4/WO3 composite showed the best photodegradation activity. The optimal conditions were obtained at catalyst dose: 0.3 g L−1, CSSZ: 8 mg L−1, initial solution pH: 3.75 and visible light irradiation time: 40 min. The pseudo-first-order rate constants of 0.013 min−1 and 0.039 min−1 (correspond to t1/2 values of 53.31 min and 17.77 min) were obtained from UV–vis and COD results, respectively. The mineralization extents of 24, 44, 59, 77 and 85.7% were respectively obtained at irradiation times of 10, 20, 25, 40 and 50 min based on COD results.

Innovative visible light photocatalytic activity for V-doped ZrO2 structure: optical, morphological, and magnetic properties

A new visible light sensitive photocatalysts based on Zr1−xVXO2 (x = 1, 3, 5, and 7) compositions for treatment of organic dyes in wastewater were investigated. Pure and V-doped ZrO2 samples were prepared by sol–gel techniques. The XRD results of the pure ZrO2 confirmed the formation of single phase tetragonal structure. Dopant-induced structure transition from the tetragonal to monoclinic phase. Based on SEM micrographs, mixture of spherical-nanorods architectures was formed in all samples with a volume ratio related to V concentration. Enhanced visible light absorption and an amazing red shift in the absorption edge were noticed in V doped ZrO2 samples. The magnetic properties of V doped ZrO2 exhibited room temperature ferromagnetism with varied hysteresis loops shape. Zr0.97V0.03O2 structure revealed a notable ferromagnetism with complete saturation magnetization of 0.038 emu/g and coercivity of 1200 Oe. Except Zr0.93V0.07O2 structure, all V doped ZrO2 samples showed significant photocatalytic activity when irradiated with visible light. The highest photocatalytic efficiency, ~100%, for methylene blue (MB) dye degradation was achieved through Zr0.95V0.05O2 catalyst under visible light irradiation time of 150 minutes. Vanadium played a major role in oxygen vacancies formation and separation of photo-induced electron–hole pairs which enriched the visible light photocatalytic activity.

Fabrication of highly active Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst photocatalyst for visible light photocatalytic degradation of levofloxacin with simultaneous hydrogen production

The capacity of redox and the separation efficiency of electron-hole pairs are important indexes for evaluating the performance of photocatalyst. Herein, a novel Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst is prepared by photo-assisted isoelectric point way. The prepared samples are characterized by XRD, SEM, TEM, EDS mappings, XPS, UV–vis, PL, TPR and EIS. The Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalytic system exposes the Ag3PO4 (1 1 0) crystal plane with strong oxidizing ability and provides a large producing hydrogen reduction surface of g-C3N4 at the same time. Therefore, the photocatalytic degradation of levofloxacin (LEV) with simultaneous hydrogen production can be effectively achieved under visible light irradiation. Besides, the influence factors such as visible light irradiation time, sacrificial agents, Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst dosage, initial pH and used times are studied systemically. Based on trapping tests and ESR analyzes, the mainly active species are confirmed in the photocatalytic degradation of LEV. Finally, the photocatalytic reaction mechanism on degradation of organic pollutants with simultaneous production hydrogen caused by Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (1 1 0) photocatalyst is proposed.

Deep eutectic solvents-derived carbon dots for detection of mercury (II), photocatalytic antifungal activity and fluorescent labeling for C. albicans.

A novel nitrogen and chloride co-doped carbon dots (N/Cl-CDs) based choline chloride-urea deep eutectic solvents (DESs) were synthesized by one-step hydrothermal method with high quantum yield of 37% and excellent photoluminescent properties. This N/Cl-CDs fluorescent probe had been successfully applied to sensitively and selectively detect the concentration of Hg2+ with a linear range of 0.2-40 μM and a detection limit of 0.05 μM. Moreover, the N/Cl-CDs displayed a strong photocatalytic antifungal activity against C. albicans and their photoinduced antifungal functions were evaluated under conditions of varying other experimental parameters. The antifungal efficiency of N/Cl-CDs (7 mg/mL) against C. albicans is upon 100% when extending the visible light irradiation time to 80 min. In addition, the excellent luminescence properties of N/Cl-CDs can also label C. albicans and displayed multicolour fluorescence imaging at different excitation wavelengths. Based on their functions of fluorescence probe, antifungal and fluorescence imaging, N/Cl-CDs would provide potentials for a wide range of applications in the detection and microbe in the near future.

A novel photocatalyst, Y2SiO5:Pr3+,Li/Pt-NaNbxTa1−xO3, for highly efficient photocatalytic hydrogen evolution under visible-light irradiation

In this work, Y2SiO5:Pr3+,Li, as an excellent up-conversion luminescence agent from visible-light to ultraviolet-light, is synthesized by using sol-gel method. And then, a series of Y2SiO5:Pr3+,Li/NaNbxTa1−xO3 (x=0.00, 0.25 and 0.50) with different amounts of Y2SiO5:Pr3+,Li are prepared by using hydrothermal method. The prepared samples are characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV–vis absorption spectroscopy and photoluminescence spectroscopy (PL). The activities of Y2SiO5:Pr3+,Li/Pt-NaNbxTa1−xO3 are investigated through photocatalytic hydrogen evolution in 10vol% methanol solution under visible-light irradiation. The influences of Nb content in NaNbxTa1−xO3, mass ratio of Y2SiO5:Pr3+,Li and NaNb0.5Ta0.5O3, visible-light irradiation time and reuse-times are examined on the visible-light photocatalytic hydrogen evolution. The experimental results showed that the prepared Y2SiO5:Pr3+,Li/Pt-NaNb0.5Ta0.5O3 with 0.4:1.0 mass ratio of Y2SiO5:Pr3+,Li and NaNb0.5Ta0.5O3 and 0.25wt% Pt loading displayed a highest evolved hydrogen activity under visible-light irradiation. This study may provide some significant references for large scale photocatalytic hydrogen evolution utilizing solar energy.

Injectable visible light-cured glycol chitosan hydrogels with controlled release of anticancer drugs for local cancer therapy in vivo: a feasible study

Currently available chemotherapy is associated with serious side effects, and therefore novel drug delivery systems (DDSs) are required to specifically deliver anticancer drugs to targeted sites. In this study, we evaluated the feasibility of visible light-cured glycol chitosan (GC) hydrogels with controlled release of doxorubicin⋅hydrochloride (DOX⋅HCl) as local DDSs for effective cancer therapy in vivo. The storage modulus of the hydrogel precursor solutions was increased as a function of visible light irradiation time. In addition, the swelling ratio of the hydrogel irradiated for 10 s (GC10/DOX) was greater than in 60 s (GC60/DOX). In vitro release test showed that DOX was rapidly released in GC10/DOX compared with GC60/DOX due to the density of cross-linking. In vitro and in vivo tests including cell viability and measurement of tumor volume showed that the local treatment of GC10/DOX yielded substantially greater antitumor effect compared with that of GC60/DOX. Therefore, the visible light-cured GC hydrogel system may exhibit clinical potential as a local DDS of anticancer drugs with controlled release, by modulating cross-linking density.

Enhanced photocatalytic performance of N-doped RGO-FeWO4/Fe3O4 ternary nanocomposite in environmental applications

Nitrogen doped RGO- FeWO4/Fe3O4 (NRGO-FeWO4/Fe3O4) ternary nanocomposite was synthesized by rapid single step microwave irradiation approach using iron acetate, ammonium tungstate and graphene oxide as precursors. The synthesized materials were thoroughly characterized by diffraction, microscopic and spectroscopic techniques. The materials were tested for their catalytic efficiency in photo degradation of Methylene Blue (MB) dye and in reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). MB was mineralized within 100 minutes of visible light irradiation time in the presence of the ternary composite, apart from excellent stability and efficiency even after 10 consecutive cycles. The composite also had the capacity to convert 4-NP into 4-AP within 45 seconds and showed very good catalytic activity even after 20 cycles. The results revealed that ternary composite has way more efficiency than the component materials and can act as a promising catalyst for various environmental and engineering applications.

Enhanced visible-light photocatalytic hydrogen evolution activity of Er3+:Y3Al5O12/PdS–ZnS by conduction band co-catalysts (MoO2, MoS2 and MoSe2)

Several conduction band co-catalysts (CBCOs), MoO2, MoS2 and MoSe2, were prepared to improve the visible-light photocatalytic hydrogen evolution activity of Er3+:Y3Al5O12/PdS–ZnS from water splitting, in which the PdS is a valence band co-catalyst (VBCO) used to facilitate the photo-generated hole transfer and the Er3+:Y3Al5O12 is an up-conversion luminescence agent from visible light to ultraviolet light used to provide the ultraviolet light satisfying the energy demands of wide band-gap ZnS photocatalyst. XRD, SEM, TEM and EDX analyses were employed to confirm the morphology, microstructure and composition of the prepared photocatalysts. UV–vis absorption and PL spectra were also determined to explore luminescence effect of the Er3+:Y3Al5O12. The visible-light photocatalytic hydrogen evolution activity of the prepared photocatalysts was evaluated by using Na2S and Na2SO3 as sacrificial reagents in aqueous solution under visible light irradiation. The influential factors such as contents of CBCOs (MoO2, MoS2 and MoSe2) and visible-light irradiation time on visible-light photocatalytic hydrogen evolution of Er3+:Y3Al5O12/PdS–ZnS–MoX2 (X = O, S and Se) were investigated in detail. Particularly, Er3+:Y3Al5O12/PdS–ZnS–MoSe2 with 0.30 wt% MoSe2 shows the highest photocatalytic hydrogen evolution activity.

Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

Visible-light driven photocatalyst (Er3+:YAlO3/Pt–NaTaO3) for hydrogen production from water splitting

NaTaO3 nanoparticles were synthesized by hydrothermal method and then the corresponding visible-light photocatalyst (Er3+:YAlO3/Pt–NaTaO3) was successfully prepared by mixing with Er3+:YAlO3 as up-conversion luminescence agent and supporting Pt as co-catalyst. The prepared Er3+:YAlO3/Pt–NaTaO3 was characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). By studying some influence factors such as Er3+:YAlO3 and Pt–NaTaO3 mass ratio, heat-treated temperature, visible-light irradiation time and solution acidity (pH) on the visible-light photocatalytic hydrogen production caused by Er3+:YAlO3/Pt–NaTaO3, it was found that the prepared Er3+:YAlO3/Pt–NaTaO3 with 0.3:1.0 mass ratio heat-treated at 500 °C for 120 min in weak acidic solution (pH = 5.0–6.0) with 5.0 wt% methanol displayed a high photocatalytic activity in hydrogen production from water solution.

Visible Light Driven Decomposition of Organic Compounds By Two Different Cocatalysts

1. Introduction Photocatalytic decomposition of organic pollutants is one of the promising method for environmental purification. Most of the researchers focused on efficient decomposition of environmental organic contaminants under visible light irradiation or indoor fluorescent light.1 Oxide-supported metal catalysts are widely acknowledged as important catalysts that are related to versatile key in photochromism, chemical sensing and photocatalytic activity. Tungsten trioxide (WO3) acts as a ideal visible light photocatalyst owing to its small band gap energy (2.4-2.8 eV) and high oxidation power of vanlence band holes. But, WO3 exhibits low photocatalytic activity due its high recombination rate of photoexcited electrons and holes. In order to suppress the recombination of photoexcited carriers and significantly increase the photocatalytic efficiency, most research has focused to prepare WO3 doping constituent or WO3 composites.2,3 In the present study, we have synthesized PtPb/WO3 and PtAu/WO3 alloy catalysts, demonstrated to exhibit the efficiency for the decompostion of organic pollutants under visible light irradiation. 2. Experimental A simple one-pot synthesis approach to obtain WO3 supported PtAu catalyst is as follows. In the synthesis, 0.5 g of WO3was suspended in 15 mL of anhyrous methanol for 15 min in a two neck round bottom flask. Pt (0.0075 g) and Au (0.0045 g) precursors were dissolved in 15 mL anhydrous methanol in the shielded vial uder Ar atmosphere and transferred to the suspensions. Then, the solution was stirred for 30 min to yield homogeneous color soluion. Required amount of NaBH4 in mehtanol was injected into the suspensions. The product were washed and centrifuged with anhydrous methanol for three times and dried under vacuum. Similar procedure was followed to synthesis the PtPb/WO3 catalyst. 3. Results and Discussion Figure 1 shows the TEM images of (a) Pt/WO3 (b) PtPb/WO3 and (c) PtAu/WO3 photocatalysts. Pt and PtPb and PtAu NPs are showed monodispersity and homogeneity on the WO3 supports. The average particle size of the three catalysts can be ranked as PtPb/WO3~PtAu/WO3 > Pt/WO3. The TEM results show that the addition of Pb and Au increases the size of NPs. Figure 2 depicts that the CO2 formation profile over different photocatalysts under visible light irradiation time. PtPb/WO3 photocatalyst (1 wt %) shows the higher rate of CO2formation over other photocatalysts. The details about the characterization and photocatalytic activity of catalysts would be discussed in the presentation. 4.

Preparation of novel hetero-nanostructures and high efficient visible light-active photocatalyst using incorporation of CNT as an electron-transfer channel into the support TiO2 and PbS

A series of novel visible light-active photocatalysts of TiO2/CNT and PbS/CNT were prepared by simple wet-chemical method and the resulting materials were used for degradation of methyl orange (MO) as probe pollutant. The reactive substances used to decorate the PbS quantum dots (QDs) with the diameters of ca. 6–10nm located onto the CNT substrate, were lead acetate (Pb(CH3COOH)) and Thiourea (NH2CSNH2) aqueous solution at 90°C. The physic-chemical properties of the resulting photocatalysts were characterized by SEM-EDX, TEM, XRD, FTIR, and UV–vis DRS spectroscopy. It was found that the size, shape, and coverage density of the PbS QDs and TiO2 nanoparticles (NPs) onto the CNT can be controlled through varying synthesis conditions. As a result, the experiments demonstrated photodegradation efficiency of ∼100% of MO, for TiO2/CNT and PbS/CNT, under 20 and 45min UV light irradiation time, respectively, and also 30 and 80min under visible light irradiation time, respectively. In addition, the possible decomposing mechanisms were also discussed. The results of the current study showed the feasible and potential use of high efficient CNT:TiO2:PbS photocatalyst in photodecomposition of toxic organic pollutants. As the above-mentioned results show, the use of CNT in photocatalyst systems is not only enhances the optical properties of TiO2 and PbS photocatalysts, but also improve their capability in photodegradation of organic pollutants.

Factorial design analysis for dye-sensitized hydrogen generation from water

A factorial design at two levels and four factors has been carried out in order to investigate the potential for hydrogen generation using Eosin Y-sensitized TiO 2/Pt catalyst under visible solar light in presence of triethanolamine (TEOA) as electron donor. The solution pH was found to be a significant parameter, and was maintained at pH 7.0 throughout the investigation. Visible light irradiation time (I-time) showed highest positive effect on hydrogen generation followed by initial Eosin Y concentration (for dye-sensitization) and the TEOA concentration while Pt content (wt %) in TiO 2 showed negative effect toward hydrogen generation. Experimental data were analyzed using both “Pareto analysis” as well as conventional regression analysis techniques. A regression function is proposed that satisfactorily predicts hydrogen generation.

Porphyrins incorporated to SiO2 gels as fluorescent materials and efficient catalysts in biomimetic photocatalytic systems

Two types of porphyrins (water-soluble and water-insoluble) were encapsulated in transparent mono- lithic silica gels. Their properties in solutions and at vari- ous steps of the sol-gel process were studied by absorption and emission electron spectroscopy. A photocatalytic sys- tem containing porphyrins immobilized in powdered silica gel for a-pinene biomimetic oxidation to pinocarveol, pi- nocarvone and myrtenol is reported. The impact of several parameters (visible light irradiation time, organic solvent, the presence of an electron acceptor/donor, and substrate concentration) on this biotransformation process was investigated and optimized. It was established that photo- chemical excitation of sol-gel immobilized metal-free porphyrins is crucial for catalyzed oxidation of monoterpenes.

Preparation of aluminum foil-supported nano-sized ZnO thin films and its photocatalytic degradation to phenol under visible light irradiation

The zinc oxide thin films on aluminum foil have been successfully prepared by sol–gel method with methyl glycol as solvent. The film was characterized by means of XRD, TG, UV–vis, SEM and AFM, which show that the ZnO/Al film is formed by a layer of ZnO nano-sized particles with average diameter of 52.2 nm. Under the initial concentration of 20 mg/L phenol solution (500 mL) and visible light irradiation time of 3 h, more than 40% of the initial phenol was totally mineralized using two pieces of ZnO/Al thin film as photocatalyst with an efficient irradiation area of 400 cm 2. It is a promising visible light responded photocatalyst for the activation of O 2 at room temperature to degrade organic pollutants.

Zinc Chelation and Photofluorochromic Behavior of Spironaphthoxazine Intercalated into Hydrophobically Modified Montmorillonite

Spironaphthoxazine (SNO) and Zn2+ were intercalated into montmorillonite interlayers hydrophobically modified by the alkyltrimethylammonium cation during UV light irradiation. The fluorescence spectra of the montmorillonite composites were observed to vary with an increase in the UV and visible light irradiation times. These composites exhibited two types of fluorescence emissions: F1, which originates from a new species, Xs, which is different from SNO (ring-closed form) and merocyanine (MC; ring-open form), and F2, which originates from the MC-Zn complex. With increasing UV light irradiation time, the F1 intensities decreased, whereas the F2 intensities increased. Xs, which is an intermediate species between SNO and MC, was transformed into MC and then coordinated with Zn2+ (i.e., MC-Zn complex) during the UV light irradiation. The reaction rate of the formation of the MC-Zn complex decreased for the hydrophobically modified montmorillonite due to a longer alkyl chain. The retrieval changes in the F1 and F2 intensities were observed with an increasing visible light irradiation time, implying the dissociation of the MC-Zn complex into Xs and Zn2+. The dissociation especially occurred for the hydrophobically modified montmorillonite with a longer alkyl chain. The formation and disappearance of Xs and the MC-Zn complex obeyed first-order kinetics, and therefore the interconversion between Xs and MC could be regarded as the rate-determining step of the whole reaction during the UV and visible light irradiations. The photoinduced reactions of the SNO species and Zn2+ were profoundly affected by the physicochemical environment provided by the clay interlayers. It is concluded that the present photoreactions can be controlled not only by the amounts of the intercalated SNO species and Zn2+, but also by the hydrophobic environment created by the surfactant molecules.

A basic study of visible light resins used for denture base. 2. Physical properties and fitness

Recently, Visible light curing resin has been on the market. This type of resin has advantage that troublesome technical process can be omitted and polymerization time can be greatly shortened in comparison with the conventional heat curing resin. But, there are few research reports related to this resin. Then, in this study, we examined its physical properties and fitness. As the results, it could be noted that hardness was changed by the visible light irradiation time. Furthermore, in the case of resin was separated and irradiated, gap between resin and mold was very small.