Structural analyses of RuO(2)-TiO(2)/Ti and IrO(2)-RuO(2)-TiO(2)/Ti anodes used in industrial chlor-alkali membrane processes

The morphology and composition of RuO(2)-TiO(2)/Ti and IrO(2)-RuO(2)-TiO(2)/Ti anodes, which have been used for the production of chlorine for more than 10 years, were analyzed by various methods; such as high-resolution scanning electron microscopy, high-resolution Auger electron spectroscopy, electron probe X-ray emission microanalysis and X-ray diffraction analysis. Drastic changes in the surface morphology, including partial exfoliation of a small amount of the oxide layer and a reduction in the content of ruthenium species through dissolution, were observed for the RuO(2)-TiO(2)/Ti anode. For the IrO(2)-RuO(2)-TiO(2)/Ti anode, on the other hand, there were moderate changes in the surface morphology and moderate dissolution of iridium and ruthenium species.ArticleJOURNAL OF APPLIED ELECTROCHEMISTRYjournal articl

Preferential {100} etching of boron-doped diamond electrodes and diamond particles by CO2 activation

The etching behavior of polycrystalline boron-doped diamond (BDD) electrodes and diamond particles with gaseous CO2 at 800 and 900 degrees C was investigated by field-emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Polycrystalline BDD (800 ppm), composed of a mixture of cubic {100} and triangular {111} orientated planes, was used so as to pursue the possibility of preferential etching by high temperature CO2 treatment. Nanometer sized pits were observed on the {100} planes while no change was observable for the {111} planes when the activation temperature was 800 degrees C. The difference in the etching behavior by CO2 with regard to the different planes was clarified using diamond particles and comparing with steam activation. The results demonstrate that CO2 activation leads to preferential {100} etching, whereas steam-activation results in preferential {111} etching.ArticleCARBON. 70:207-214 (2014)journal articl

Intensity-modulated irradiation for superficial tumors by overlapping irradiation fields using intensity modulators in accelerator-based BNCT

The distribution of the thermal neutron flux has a significant impact on the treatment efficacy. We developed an irradiation method of overlapping irradiation fields using intensity modulators for the treatment of superficial tumors with the aim of expanding the indications for accelerator-based boron neutron capture therapy (BNCT). The shape of the intensity modulator was determined and Monte Carlo simulations were carried out to determine the uniformity of the resulting thermal neutron flux distribution. The intensity modulators were then fabricated and irradiation tests were conducted, which resulted in the formation of a uniform thermal neutron flux distribution. Finally, an evaluation of the tumor dose distribution showed that when two irradiation fields overlapped, the minimum tumor dose was 27.4 Gy-eq, which was higher than the tumor control dose of 20 Gy-eq. Furthermore, it was found that the uniformity of the treatment was improved 47% as compared to the treatment that uses a single irradiation field. This clearly demonstrates the effectiveness of this technique and the possibility of expanding the indications to superficially located tumors

Development of optimization method for uniform dose distribution on superficial tumor in an accelerator-based boron neutron capture therapy system

To treat superficial tumors using accelerator-based boron neutron capture therapy (ABBNCT), a technique was investigated, based on which, a single-neutron modulator was placed inside a collimator and was irradiated with thermal neutrons. In large tumors, the dose was reduced at their edges. The objective was to generate a uniform and therapeutic intensity dose distribution. In this study, we developed a method for optimizing the shape of the intensity modulator and irradiation time ratio to generate a uniform dose distribution to treat superficial tumors of various shapes. A computational tool was developed, which performed Monte Carlo simulations using 424 different source combinations. We determined the shape of the intensity modulator with the highest minimum tumor dose. The homogeneity index (HI), which evaluates uniformity, was also derived. To evaluate the efficacy of this method, the dose distribution of a tumor with a diameter of 100 mm and thickness of 10 mm was evaluated. Furthermore, irradiation experiments were conducted using an ABBNCT system. The thermal neutron flux distribution outcomes that have considerable impacts on the tumor’s dose confirmed a good agreement between experiments and calculations. Moreover, the minimum tumor dose and HI improved by 20 and 36%, respectively, compared with the irradiation case wherein a single-neutron modulator was used. The proposed method improves the minimum tumor volume and uniformity. The results demonstrate the method’s efficacy in ABBNCT for the treatment of superficial tumors

The Effect of Li x Ni2-x O2/Ni with Modification Method on Activity and Durability of Alkaline Water Electrolysis Anode

International audienceWater electrolysis requires durability during a fluctuating power supply in power-to-gas application with renewable energies. The previously developed lithiated NiO modified Ni (Li (x) Ni2-x O-2/Ni) has a high catalytic activity and durability during potential cycling, whereas the relatively high surface oxide resistance due to preparation of the oxidation at high temperature with a LiOH coating. In order to improve the catalytic activity, we proposed optimization of the oxide layer by thermal decomposition with various precursor coatings. The oxide layers prepared with acetate and nitrate precursors were dense and porous, respectively. The initial activity obtained from the acetate precursor electrode was higher than that of the nitrate precursor and the oxidation with the LiOH coating. Although the nitrate precursor electrode suffered from the same degradation as the Ni anode during potential cycling, the activity of the acetate precursor electrode as well as the oxidized electrode with the LiOH coating increased, and the activity for the former was almost the same as the initial Ni anode after 20,000 cycles. The lower preparation temperature of the acetate precursor would suppress the formation of the electron resistive nickel oxide between the base nickel and lithiated NiO, which was observed for the oxidized electrode with the LiOH coating as well. While the double-layer capacitance and redox peak around 1.3 V vs. RHE of the Ni and the nitrate precursor electrode significantly increased with Ni(IV) formation during potential cycling, those of the acetate precursor electrode slightly increased without any Ni(IV) formation. Therefore, the dense Li (x) Ni2-x O-2 prepared with acetate has a good electric conductivity and catalytic activity with a high durability during potential cycling as the anode of an alkaline water electrolyzer for renewable power sources