Effective Sol-Gel Nanocoatings on ZnO Electrodes for Suppressing Recombination in Dye-Sensitized Solar Cells

Attempts have been made to improve the performance of dye-sensitized solar cells by forming metal-oxide nanocoating layers on ZnO electrodes by a sol-gel transformation. SiO2, Nb2O5, TiO2, or ZrO2 nanocoating layers could be formed by dipping ZnO films into metal alkoxide solutions of low concentrations and subsequent heat treatments. The performance of DSSCs using the coated ZnO electrodes depends strongly on the structure of coating layers such as the thickness and the surface coverage, which are significantly influenced by the coating conditions. In particular, SiO2 and Nb2O5 coating layers are effective to suppress the recombination by constructing the energy barrier at the ZnO/electrolyte interface and enhance energy conversion efficiency. It is found that the coating layers also hinder the grain growth of ZnO, contributing to the enhanced cell performance as well

Noninvasive vessel-selective perfusion imaging with intravenous myocardial contrast echocardiography

Background Intravenous myocardial contrast echocardiography (MCE) cannot identify each perfusion area of coronary vessels separately. However, by destroying microbubbles passing through a specific vessel using high-power ultrasound during intravenous MCE, vessel-selective perfusion imaging (VSPI) may be feasible. Methods In 10 open-chest dogs, intermittent short-axis images were obtained during contrast agent infusion using an ultrasound system. For VSPI, a probe coupled to another ultrasound machine was placed on the proximal left circumflex coronary artery (LCx). High-power ultrasound pulses were transmitted to destroy bubbles passing through the LCx. A negative contrast area on VSPI was considered to represent the perfusion area of the LCx (LCx-VSPI). A negative contrast area on conventional MCE during LCx occlusion and a region without staining by Evans blue dye were used as gold standards for defining the LCx perfusion area. LCx-VSPI was compared with a negative contrast area on conventional MCE during LCx occlusion and a region without staining by Evans blue dye. Results Despite lack of LCx occlusion, high-power destructive pulses produced a definite area of negative contrast on the LCx region. Decreased power of ultrasound pulses resulted in disappearance of the negative contrast area. An excellent relationship was demonstrated between both LCx-VSPI and a negative contrast area on conventional MCE during LCx occlusion (r = 0.93, P < .0001), and LCx-VSPI and a region without staining by Evans blue dye (r = 0.92, P = .0002). Conclusion: VSPI during intravenous MCE may be feasible for noninvasive assessment of perfusion areas associated with specific vessels.Asanuma T, Fujihara T, Otani K, Miki A, Ishikura F, Beppu S. Noninvasive vessel-selective perfusion imaging with intravenous myocardial contrast echocardiography. J Am Soc Echocardiogr. 2004 Jun;17(6):654-8. doi: 10.1016/j.echo.2004.03.011

Fabrication of layered hydroxide zinc nitrate films and their conversion to ZnO nanosheet assemblies for use in dye-sensitized solar cells

Layered hydroxide zinc nitrate (LHZN; Zn5(NO3)2(OH)8·xH2O) films were fabricated on glass or plastic substrates by a chemical bath deposition method combined with a homogeneous precipitation in methanolic solutions. High- or low-temperature pyrolytic decomposition of the LHZN films having two-dimensional morphology was attempted to obtain porous ZnO nanosheet-assembly films. The LHZN films were converted into porous ZnO films by pyrolyzing at temperatures above 400 °C, while porous LHZN/ZnO hybrid films were obtained by pyrolyzing at a lower temperature of 120 °C without morphological changes. The pyrolyzed ZnO films were applied to dye-sensitized solar cells (DSSCs), resulting in the generation of relatively high open-circuit voltages. The low-temperature pyrolysis enabled us to fabricate the LHZN/ZnO film even on the plastic substrate. Actually a cell using the LHZN/ZnO film on an indium tin oxide-coated polyethylene naphthalate substrate showed an energy conversion efficiency of 2.08% with a high open-circuit voltage around 0.70 V

Endoscopic hemostasis with endoscopic mucosal resection and multiple synchronous early gastric cancers: a case report

Abstract Introduction Endoscopic hemostasis for severe upper gastrointestinal bleeding due to tumors, such as gastrointestinal stromal tumors and malignant lymphoma, is temporarily effective. However, permanent hemostasis is difficult in many cases because of diffuse bleeding. Case presentation A 60-year-old Japanese woman was admitted to our hospital with hematemesis. Endoscopy revealed multiple gastric polyps and fresh blood in her stomach. One of the gastric polyps, which was associated with oozing bleeding, was found near the anterior wall of the lower gastric body. We initially applied hemostatic forceps and argon plasma coagulation over the tumor surface, but the bleeding persisted. After endoscopic mucosal resection, exposed vessels were seen at the base of the mucosal resection site with oozing bleeding. Coagulation of the bleeding vessels using hemostatic forceps allowed successful completion of the hemostatic procedure. Our patient also had eight synchronous gastric cancer lesions. Histological examination of the resected specimens showed various types of cancer. Conclusion This is a case report of gastric cancer associated with eight gastric cancer lesions, confirmed by histology, in which hemostasis was achieved through endoscopy.</p

Simplified Submucosal Tunneling Biopsy Using Clip-With-Line Traction and Closure for Gastric Subepithelial Lesion

Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) has emerged as a standard and convenient method for the sampling of subepithelial lesions (SELs). Immunohistological analysis is required to definitively distinguish mesenchymal tumors; however, EUS-FNA provides insufficient material to achieve this, especially for small SELs &lt; 2 cm. We therefore previously reported a novel submucosal tunneling biopsy (STB) technique that utilizes endoscopic submucosal dissection (ESD) for sampling SELs. However, unresolved advanced technical issues have hindered its widespread application. Currently, a counter-traction technique is used to facilitate ESD. We here describe a technically simplified STB technique using clip-with-line traction for gastric SELs