Green synthesis of mesoporous hematite (α-Fe2O3) nanoparticles and their photocatalytic activity

A green synthesis method for the preparation of mesoporous α-Fe₂O₃ nanoparticles has been developed using the extract of green tea (camellia sinensis) leaves. This simple and one-step method can suitably be scaled up for large-scale synthesis. The as-prepared mesoporous nanoparticles were characterized by SEM, TEM, XRD, XPS, Raman, UV–visible spectroscopy and N₂ adsorption analysis. The nanoparticles were highly pure and well crystallized with an average particle size of 60 nm. The photocatalytic activity of nanoparticles was evaluated by the amount of hydroxyl radical formation under visible light irradiation detected by fluorescence spectroscopy. The as-prepared α-Fe₂O₃ showed two times higher activity than commercial α-Fe₂O₃ in term of hydroxyl radical formation and enhanced performance in a photoelectrochemical cell. Also, a plausible mechanism for the formation of mesoporous α-Fe₂O₃ has been suggested.     

Materials dynamics under nanosecond pulsed pressure loading

A nanosecond pressure pulse is generated by focusing a nanosecond-pulsed laser onto an aluminum target with plasma confined geometry. A spatially uniform pressure pulse is generated by focusing laser beams with a flat-top spatial energy distribution. High-pressure pulse loading and recovery experiments were performed on yttria-doped (3 mol%) tetragonal zirconia polycrystals at 11 GPa. In the pressure-loaded region, the monoclinic phase was uniformely formed. The transition ratio was approximately 30%. Nanosecond time-resolved Raman spectroscopy was performed on polytetrafluoroethylene under high-pressure pulse loading at 1 GPa, and rapid structural phase transition within 10 ns was revealed.     

Comparative assessment of the efficiency of Fe-doped TiO2 prepared by two doping methods and photocatalytic degradation of phenol in domestic water suspensions

Fe-doped TiO₂ particles responding to visible light were synthesized by impregnation and calcination method using TiO₂ particle and Ti element, respectively. The optical and the chemical properties were characterized by measuring the X-ray diffraction (XRD) and UV–visible spectroscopy. The onset of absorption shifted to longer wavelengths on doping TiO₂ by the calcination process, which showed a better response as compared to the impregnation method. The photocatalytic reactivity was evaluated by the degradation of phenol with impregnated Fe-doped (0.5% w/w in Fe) and calcined Fe-doped (Fe_xTi_{1 x}O₂, x ¼ 0.005 (Fe/Ti molar ratio)) TiO₂ separately in distilled and tap water. The characterization results have confirmed the advanced possibility of correlation between photoactivity and the special property of sulfur-containing calcined Fe-doped TiO₂. In case of the coagulation of the undoped A-I and the Fe-doped B-I, the photoactivity showed a decrease due to the presence of natural electrolytes and due to the high pH of tap water, whereas in the case of the coagulation of calcined Fe-doped TiO₂ prepared from sulfides (Fe_xTiS₂), the photoactivity showed an increase. In this study, highest catalytic activity was found to be strongly dependent both on catalyst structure and on the type of water used.     

Application of a modular multilevel cascade converter (MMCC‐SDBC) to a STATCOM. Control of active power and negative‐sequence reactive power

This paper presents the application of a modular multilevel cascade converter based on single‐delta bridge‐cells (MMCC‐SDBC) to a STATic synchronous COMpensator (STATCOM), particularly for negative‐sequence reactive‐power control. The SDBC is characterized by cascade connection of multiple single‐phase H‐bridge (or full‐bridge) converter cells per leg, which facilitates ?exible circuit design, low voltage steps, and low electromagnetic interference (EMI) emissions. However, there is no published report on such a STATCOM with experimental veri?cation or a control strategy. This paper designs, constructs, and tests a 100‐V 5‐kVA PWM STATCOM based on the SDBC with focus on the operating principle and performance. Experimental results con?rm that this converter can control not only the positive‐sequence reactive power but also the negative‐sequence reactive power and low‐frequency active power intended for the ?icker compensation of arc furnaces. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 33–44, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22365     

Poly(p-maleimidostyrene) as a macromolecule initiator for polymerization of styrene-type monomers - Synthesis of block copolymers containing poly(p-maleimidostyrene) with highly reactive pendent maleimido groups

4-Substituted styrenes (substituent: methoxy, methyl, acetoxy, maleimido and none), were cationically polymerized with an initiator system involving poly(p-maleimidostyrene)(PMS) as a macroinitiator, having highly reactive pendent maleimide moieties and a α-chlorobenzyl structure at the polymer end. Using PMS/SnCl₄/tetra-n-butylammmonium chloride initiator system, block copolymers of 4-substituted styrenes onto PMS were obtained in CH₂Cl₂ at 0 °C. As for the polymerization of N-(4-vinylphenyl)maleimide and 4-acetoxystyrene, especially, PMS as the macroinitiator was almost completely utilized for initiation reaction and the polymers having PMS-b-poly(4-substituted styrene) platform with very narrow and unimodal molecular weight distribution were formed in contrast with the case of using 4-methoxystyrene and 4-methylstyrene with stronger electron releasing groups, in which the molecular weight distributions of the formed polymeric materials appeared to be bimodal.     

Pd/SiO2 catalyst for oxidation of benzene to phenol

Usefulness of silica supported palladium catalysts applied for the hydroxylation reaction of benzene under ambient conditions has been demonstrated. Two types of catalyst, Pd alone and CuPd composite catalysts both being supported on silica, were found to behave in remarkably different ways which are dependent also on the mode of reactant gas feeding. The Pd single component catalyst is powerful when hydrogen and oxygen are simultaneously present in the reacting system and produces phenol almost exclusively. On the other hand, the composite catalyst can be used irrespective of the mode of gas feeding. If quinones are desired, the use of the composite catalyst is recommended but if phenol is desired the Pd single component catalyst seems to be advantageous.     

Elimination of a back-reflected TE mode in a TM-mode optical isolator with a Mach-Zehnder interferometer

Eimination of a back-reflected TE mode traveling in a TM-mode optical isolator was investigated. The optical isolator had a Mach-Zehnder interferometer that included a polarization-dependent reciprocal phase shifter in one of the arms. The reciprocal phase shift was achieved by an optical path difference between the two arms. By adjustment of the length of the reciprocal phase shifter, the interferometer prevented the back-reflected TE mode from coupling into an input port of the isolator. An extinction ratio of more than 18 dB was obtained against the back-reflected TE mode at a wavelength of 1.55 microm.     

Validation and verification of the ICRP biokinetic model of 32P: the criticality accident at Tokai-Mura, Japan

Regrettably, a criticality accident occurred at a uranium conversion facility in Tokai-mura, Ibaraki, Japan, on 30 September 1999. Radioactivities of 32P in urine, blood and bone samples of the victims, who were severely exposed to neutrons, were measured. 32P was induced in their whole bodies at the moment of the first nuclear release by the reaction 31P (n, gamma) 32P and 32S (n, p) 32P. A realistic biokinetic model was assumed, as the exchange of 32P between the extracellular fluid compartment and the soft tissue compartment occurs only through the intracellular compartment, and the model was used for preliminary calculations. Some acute excretion of 32P, caused by decomposition or elution of tissues which occurred at the time of the accident, may have happened in the victims' bodies in the first few days. The working hypotheses in the present work should initiate renewed discussion of 32P biokinetics.