Showing papers by "Akira Fujishima published in 2007"
TL;DR: Water splitting and environmental cleanup are two active fields in heterogeneous photocatalysis, which are both closely related to the research in semiconductor photoelectrochemistry since the 1960s.
497 citations
TL;DR: In this paper, the photoinduced conversion of composition on TiO2-based nanofibers may find applications in photocatalysis, antibacterial technology, and other areas.
Abstract: Silver−TiO2 nanofibers (Ag/Ti = 1/50) were fabricated by the electrospinning method, followed by heat treatment at 200 °C and calcination at 550 °C. The electrospinning solution was comprised of AgNO3 and titanium tetraisopropoxide (TTIP) with polyvinylpyrrolidone (PVP). Alternating irradiation of the silver−TiO2 nanofibers with ultraviolet and visible light can interconvert the silver species on the TiO2-based nanofibers to yield Ag metal and Ag2O, respectively, and this process has been characterized by UV−visible spectra, TEM, XRD, and XPS. The interconversion process can be rationalized in terms of the photoreduction of Ag2O by TiO2 and the oxidization of Ag by visible light. Acetaldehyde photodecomposition measurements indicate that Ag2O has better mineralization ability than Ag0 in this kind of silver−TiO2 nanofiber photocatalytic system. The photoinduced conversion of composition on TiO2-based nanofibers may find applications in photocatalysis, antibacterial technology, and other areas.
107 citations
TL;DR: T titanium dioxide (TiO2)‐coated catheters for CIC are made using technology developed previously, and the photocatalytic antibacterial effect of this catheter using only light energy and the safety of this type of catheter for practical clinical use are examined.
Abstract: Objective: Clean intermittent catheterization (CIC) requires a large number of disposable catheters or a large amount of water and disinfectant. We made titanium dioxide (TiO2)-coated catheters for CIC using technology we have developed previously, and examined the photocatalytic antibacterial effect of this catheter using only light energy and the safety of this type of catheter for practical clinical use.
Methods: TiO2-coated catheters were filled with bacterial cell suspensions and illuminated with a 15-W black-light lamp for testing antibacterial potency. Next, we soaked control toxic materials (zinc diethyldithiocarbamate) and the tips of TiO2-coated catheters in M05 medium, and evaluated cell toxicity from the numbers of V79 colonies in these dilutions. Then, bodyweight curves and histological tissue changes were observed over a period of time in mouse-transplanted TiO2-coated catheters and control catheters. Finally, we investigated the use of these TiO2-coated catheters in 18 patients by questionnaire and bacterial culture of TiO2-coated catheters and control catheters.
Results: The survival rate of Escherichia coli in the liquid inside the TiO2 catheter decreased to a negligible level within 60 min under ultraviolet (UV)-A illumination. The survival rate of Staphylococcus aureus, Pseudomonas aeruginosa and Serratia marcescens also decreased to a negligible level within 60 min. V79 cells showed no cytotoxicity of this catheter, and there was no difference in bodyweight or foreign body reaction between mouse-transplanted TiO2-coated catheters and control catheters. In a preliminary clinical analysis of 18 patients who voluntarily used this catheter, the rate of positive bacterial culture of the tips of TiO2-coated catheters was 20% versus 60% for conventional catheters after 4 weeks of use.
Conclusion: TiO2-coated silicone catheters were easily sterilized under certain light sources and were shown to be safe in an experiment using cultured cells and in animal experiments. Sterilizing catheters with TiO2 photocatalyst thin films are expected to be used clinically for clean intermittent catheterization after proper modification based on this study.
59 citations
TL;DR: In this paper, the X-ray diffraction patterns of WO 3 bilayer films were analyzed using radio frequency magnetron sputtering in a mixed gas of 80%Ar-20%O 2.
10 citations
TL;DR: In this paper, the reactive facing-target sputtering method was used to deposit WO3 thin films from a metal tungsten disk in an Ar+O2 mixture gas atmosphere at different sputtering pressures.
Abstract: The reactive facing-target sputtering method was used to deposit WO3 thin films from a metal tungsten disk in an Ar+O2 mixture gas atmosphere at different sputtering pressures. X-ray diffraction, scanning electron microscopy (SEM), UV-visible spectrophotometer, and Raman studies were performed to study structural, surface morphology, and optical properties of the as-deposited and annealed samples. Annealing treatments were done in oxygen atmospheres. All the as-deposited films were amorphous in structure. The films annealed at 400°C and deposited at 200W show preferential orientation. SEM images show nanorodlike growth for the films deposited at a sputtering pressure of 0.15Pa and annealed at 400°C. The optical absorption edge of the as-deposited films prepared at the sputtering pressures of 0.8–0.15Pa varied between 340 and 380nm and shifted up to 480nm when the samples were annealed at 400°C. From Raman spectra, we observed the O–W6+–O bonds, and the W6+O stretching mode of terminal atoms on the surfac...
6 citations