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The preparation and exfoliation of graphite oxide at low temperatures (near room temperature) to produce exfoliated graphite (EG) instead of rapid heating to a high temperature (conventional process) are reviewed. The exfoliation by microwave irradiation, electrochemical exfoliation and surfactant-assisted exfoliation of graphite are also included because these techniques can be applied under ambient atmosphere, although last two techniques were mainly applied for thinning the graphite flakes to obtain “graphene” flakes. The applications of the resultant exfoliated graphite (EG) for oil/water separation, adsorptive removal of the environment pollutants and microwave shielding are shortly reviewed.

This paper reports beam wave intensity fluctuations in uplink (ground-to-satellite) laser beam transmission caused by atmospheric turbulence. Intensity fluctuation in the strong region was apparently induced by uplink measurement in previous experiments. Statistical values of the uplink fluctuation were estimated by numerical calculation using moment equation analysis with thin phase screen approximation. The beam profile of the uplink, the scintillation index, and the covariance of the uplink intensity fluctuation were calculated using models of the refractive index structure constant. The generation of strong intensity variation was explained as the result of a speckle pattern on the receiving plane at the satellite produced by atmospheric turbulence when scanned along with trajectory of the satellite.

To demonstrate chiral induction and amplification in the solid state, we investigated co-crystals prepared from (S)- or (R)-1-phenylethylamine and achiral biphenyl-4-carboxylic acid by solvent-free crystallization. The chiroptical and optical properties of the co-crystals were characterized by circular dichroism spectroscopy, Fourier transform infrared spectroscopy, and time-dependent density functional theory calculations, revealing chiral induction, and amplification in the solid phase.The anisotropy factors-time plot showing the circular dichroism (CD) enhancement of the co-crystal prepared from chiral amine and achiral compounds by solvent-free crystallization in the KBr matrix. A correlation was shown between CD enhancement and the uptake of water on the KBr disk.

Herein, the edges in carbon materials were quantitatively evaluated by summing the amount of hydrogen and the amount of functional groups without hydrogen in the material. The amount of hydrogen in the carbon material was quantitated via temperature-programmed oxidation (TPO) under an oxygen atmosphere, whereas the amount of functional groups was determined via temperature-programmed desorption (TPD) of the sample under an inert atmosphere. Consequently, the amount of edges in exfoliated carbon fibers prepared from polyacrylonitrile (PAN) (referred to as PAN-1000) was 9.4 mmol g−1. In addition, Ketjen Black (KB) and activated carbon (AC) had edge content of 1.3 and 3.6 mmol g−1, respectively. Because the total amount of functional groups of PAN-1000, KB and AC were estimated to be 8.18, 0.082 and 1.02 mmol g−1via TPD, the total amount of edges and oxygen-containing functional groups of each sample could be quantified. The difference between amount of edges and the amount of functional groups is speculated to correspond to the amount of edges terminated with hydrogen. This study revealed that detailed information about the edges such as their proportion terminated with oxygen-containing functional groups, the species and amount of oxygen-containing functional groups via a combination of TPO and TPD.

Polyzwitterions that show the alternation of net charge in response to external stimuli have attracted great attention as a new class of surface-polymers on nanomedicines. However, the correlation between their detailed molecular structures and expression of antifouling properties under physiological condition remain controversial. Herein, we synthesized a series of ethylenediamine-based polyzwitterions with carboxy groups/sulfonic groups and ethylene, propylene, and butylene spacers as potential surface-polymers for nanomedicines, allowing sensitive recognition of tumor acidic environments (pH = 6.5–5.5). Then, we evaluated their structure-based characteristics, including pH-dependent cellular uptakes and intracellular distributions. Additionally, the role of conformation stability, i.e., Gibbs free energy changes, was to induce an intramolecular electrostatic interaction in the zwitterionic moieties. These results highlight the practicality of fine-tuning the design of zwitterionic moieties on polymers for the future development of nanomedicines that can recognize the narrow pH window in tumor acidic environments.

We investigated the oxygen electrode reactions (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)) of a pyrochlore-type metal oxide containing Bi and Ru (BRO), for aqueous air batteries. Here, we report the correlation between the calcination temperature of BRO and its catalytic activity in a KOH aqueous solution. It was found that the number of oxygen vacancies of BRO increased and the Tafel slopes for the ORR and OER decreased with an increase in the calcination temperature. The results of this study suggest that the oxygen vacancies of BRO are one of the factors that determine the catalytic activity for not only the ORR but also the OER.

Self-standing carbonaceous sheets were obtained from phyllostachys (bamboo), and their potential for use as the gas diffusion layer (GDL) of polymer electrolyte fuel cells (PEFCs) was investigated. Addition of polyvinyl alcohol (PVA) to bamboo fiber sheet was investigated in the present study. Addition of PVA gives increasing in the electrical conductivity, durability, and higher power density of the resultant PEFC single cell. The maximum power of GDL using bamboo and PVA was 155 mW cm-2, whereas it was 170 mW cm-2 for a conventional GDL composed of carbon fibers.

The degradation of Pt/C in HClO4 solution was investigated using identical location field emission scanning electron microscopy (IL-FE-SEM) and inductively coupled plasma-mass spectrometry (ICP-MS) during potential pulse acceleration degradation tests (ADT). Typical morphological changes such as particle shrinkage and growth, disappearance, migration, coalescence, and precipitation on the carbon support were observed for Pt particles. The precipitation was a minor part of the deterioration process and was observed after the 5,000th pulse. The largest number of particles either disappeared or shrunk. Hence, these processes were considered to be the largest contributors to deterioration under the ADT. In addition, the migration distance of the Pt particles was generally less than 4 nm.

Urethane foam mattresses are commonly used as cushioning when placing panel flooring on the floor slab of a building. Urethane foam consists of elastic fibres with pores. Both elements can affect the performance of the insulation against impact sounds. However, these effects have not yet been detailed, and they may change if the material properties or constitution of the fibres and pores in the cushioning change. In this paper, we propose an analytical model for use in evaluating the performance of insulation against floor impact sound. This model was used to examine the contribution of the pores versus the elastic fibres to wave transmissions from the flooring surface to the slab. The results reveal that the constitution of the foam (either open or closed cells of pores) and the thickness and hardness of the cushion layer strongly affect the sound insulation performance of the floor.

A composite catalyst (LaMnO3-CNF), containing LaMnO3 and carbon nanofiber (CNF), was prepared by a co-precipitation method for use as a cathode catalyst in metal hydride (MH)/air battery. The catalytic activities for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) were investigated in aqueous KOH. The onset potential for the ORR of CNF and the composite catalyst was estimated to be 0.84 V and 0.91 V vs. a reversible hydrogen electrode (RHE), respectively. To estimate the onset potential for the OER, in-situ OER measurements were carried out using a dissolved oxygen sensor during chronoamperometry at the charging potential of a MH/air battery. The onset potential was found to be 1.65 V for CNF and 1.60 V for the composite catalyst.

Carbonaceous sheets were obtained from phyllostachys (bamboo), and their potential for use as the gas diffusion layers (GDLs) of proton exchange membrane fuel cells (PEMFCs) was investigated. Fibers, which were mainly composed of cellulose, were obtained from phyllostachys via roll-pressing and chemical treatment in an autoclave with 0.1 mol dm-3 NaOH solution, followed by defibration by an electric blender. The fibers were molded into a sheet by a papermaking procedure. The fibrous morphology remained even after carbonization under an Ar atmosphere at 1000 - 3000oC. The electric conductivity increased as the carbonization temperature was raised up to 2500oC. A single PEMFC operation test was carried out by using the carbonaceous fiber sheet as the GDL. The maximum power was 140 mW cm-2, whereas it was 170 mW cm-2 for a conventional GDL composed of carbon fibers.

Phyllostachys, which is generally called as "bamboo", is one of the sustainable natural resources with high CO2 immobilization capacity and is expected to use in the next generation. In the present study, the carbonaceous sheets are prepared from phyllostachys through a series of physical, chemical and heat treatments. The average diameter of obtained single bamboo fiber was ca. 12.5 mm and is reduced by the carbonization; on the other hand, the microscopic morphology is remained "fibrous". The electric conductivity, which is measured by four-probe method, is 35 S cm-1 after heat treatment at 2000oC in this study. From the cyclic vlotammogram obtained in in 0.1 mol dm-3 of perchloric acid aqueous solution under N2 atmosphere, significantly current flow due to an electrochemical reaction is not recognized and only electrochemical double layer capacity can be observed. The results of this study suggest that phyllostachys could be used to for the material of the electrochemical devices.

A number of small ultrasonic transducers were placed on a flat surface to form a directional ultrasonic sound source. A standing wave field with a hexagonal distribution of sound pressure like a honeycomb was formed when ultrasonic waves were superimposed from three directions using three of these sources. Small objects could be trapped at the nodes of the sound pressure in the sound field. When the phase of the three sources was changed, the sound pressure distribution shifted in the direction of the sound axis of the sources, and the objects trapped at the pressure nodes also shifted. For more stable object trapping, the ultrasonic transducers were placed on the inner wall of a semicylinder and the ultrasonic waves were focused to form a thin two-dimensional planar standing wave field. Three of these sources were used in the experiment, and it was possible to manipulate the objects more stably.

Time- and frequency-domain numerical models are developed to investigate the acoustic performance of metascreen-based coatings for maritime applications. The coating designs are composed of periodic air-filled cavities embedded in a soft elastic medium, which is attached to a hard backing and submerged in water. Numerical results for an acoustic coating with cylindrical cavities are favorably compared with analytical and experimental results from the literature. Frequencies associated with peak sound absorption as a function of the geometric parameters of the cavities and material properties of the host medium are predicted. Variation in the cavity dimensions that modifies the cylindrical-shaped cavities to flat disks or thin needles is modeled. Results reveal that high sound absorption occurs when either the diameter or length of the cavities is reduced. Physical mechanisms governing sound absorption for the various cavity designs are described.

The results of the investigations on the photodegradation of a non-steroidal anti-inflammatory drug ibuprofen sodium salt (IBU) in a photocatalytic membrane reactor (PMR) coupling photocatalysis using suspended TiO2and direct contact membrane distillation are described. The influence of solution composition in terms of (i) pH (pH 3, pH 6.5 and pH 10), (ii) presence of inorganic salts (NaCl, Na2SO4, NaHCO3, NaNO3and Na3PO4) and (iii) turbidity (bentonite, 13.5 - 103 NTU) on the effectiveness of IBU removal was especially investigated. The highest effectiveness of IBU photodegradation was obtained at pH 6.5. No influence of the presence of NaCl, NaNO3and Na2SO4on the effectiveness of degradation and mineralization of IBU was found. NaHCO3and Na3PO4 did not affect the effectiveness of degradation of IBU; however, the efficiency of mineralization decreased significantly. The increased turbidity of feed solution did not affect IBU removal in the PMR.

The present paper describes photodegradation of non-steroidal anti-inflammatory drug ibuprofen sodium salt (C13H17O2Na) in a new hybrid system coupling photolysis and direct contact membrane distillation (DCMD). Photodegradation was conducted using UV254germicidal lamp. The initial concentration of C13H17O2Na was c0= 0.05, 0.1, 0.2 or 0.4 mmol/dm3. After 5 h of the process the mass of C13H17O2Na in the feed decreased for 99.8-96.7% for c0 of 0.05-0.4 mmol/dm3, respectively. The amount of total organic carbon (TOC) in the feed was lowered by ca. 75%, regardless of initial C13H17O2Na concentration. Among the volatile compounds which passed through the membrane low amounts of C13H18O2(0.04-0.16 μmol) and some other organic compounds measured as TOC (1.2-3.7 mg) were present. The conductivity of distillate did not exceed the value of 2.6 μS/cm and pH was about 5.7. The total effectiveness of organics removal was 99.97-99.99% for C13H18O2and 94.8- 98.0% for TOC, dependent on initial concentration of ibuprofen sodium salt.

Barium titanate (BaTiO3) and strontium titanate (SrTiO3) nanoparticles were synthesized separately through hydrothermal reaction of crystalline TiO2 particles and corresponding alkaline earth hydroxides, Ba(OH)2 and Sr(OH)2 respectively, in 50 mol·dm−3 KOH solution at 150°C. Each structural evolution of BaTiO3 and SrTiO3 during the hydrothermal treatment was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), field emission transmission electron microscopy (FE-TEM) and thermogravimetry-differential analysis (TG-DTA). In the BaTiO3 system, round particles with cubic perovskite-type structure were obtained within 1 h. However, these particles were gradually dissolved and then were re-precipitated in the form of cube-shape BaTiO3 particles with a smaller lattice constant a c than that of the former phase. After the BaTiO3 particles formed firstly have disappeared completely, or the two phases coexistence stage with different lattice constant a c passed, lattice constant a c of BaTiO3 phase re-precipitated continuously decreased with annealing time. In contrast, once SrTiO3 particles are formed, the lattice constant a c decreased continuously throughout the reaction. The result indicates that SrTiO3 particles were annealed without dissolution and precipitation process under the present condition. [Copyright &y& Elsevier]

Titania nanofiber was attempted to be partly nitrided by direct heat-treatment in ammonia gas flow at 800~1000{degree sign}C, in order to add the high electron conductive property of titanium nitride into titania to make titanium compounds having both lithium insertion ability and high electron conductivity in one particle. The resulted compounds from the fiber showed a good rate-capability of reversible lithium insertion even without any addition of conductive-support material, such as carbon black.

Carbon vanadium nitride composite was prepared as an active material in lithium ion battery with high-rate capability through carbothermal reduction of fibrous NH4+ intercalated vanadium xerogel at above 1000 oC under nitrogen gas flow. Carbon-vanadium nitride composite prepared showed reversible electrochemical lithium insertion/extraction in 1M LiBF4 EC/DEC electrolyte, discharge capacity down to 0 V being 240, 180, and 125 mAh g-1 at current density of 50, 100, and 1000 mA g-1 respectively.

Carbon modified TiO2photocatalysts for water purificationCarbon can form different structures with TiO2: carbon-doped TiO2, carbon coated TiO2and composites of TiO2and carbon. The presence of carbon layer on the surface of TiO2as well as the presence of porous carbon in the composites with TiO2can increase the concentration of organic pollutants on the surface of TiO2, facilitating the contact of the reactive species with the organic molecules. Carbon-doped TiO2can extend the absorption of the light to the visible region by the narrowing of the band gap and makes the photocatalysts active under visible light irradiation. TiO2loaded carbon can also work as a photocatalyst, on which the molecules are adsorbed in the pores of carbon and then they undergo the photocatalytic decomposition with UV irradiation. Enhanced photocatalytic activity for the destruction of some organic compounds in water was noticed on the carbon coated TiO2and TiO2loaded activated carbon, mostly because of the adsorptive role of carbon. However, in carbon-doped TiO2, the role of carbon is somewhat different, the replacement of carbon atom with Ti or oxygen and formation of oxygen vacancies are responsible for extending its photocatalytic activity towards the visible range.

Preparation of carbon coated FeWO4 was carried out by heat treatment of WO2.9 with iron acetate at 400oC, followed by carbonization with poly(vinyl alcohol) (PVA) as carbon precursor at 800oC in N2 atmosphere. The powders mainly consist of FeWO4. The photocatalytic activities of their samples were confirmed by phenol photodecomposition in its aqueous solution. Carbon coated FeWO4 powders revealed photocatalytic activity under visible light. However, the photocatalytic activity of FeWO4 without carbon coating could not be detected. Carbon coating to the FeWO4 derived the photocatalytic activity under visible light irradiation. An addition of 10% PVA to the carbon coating derived the highest photocatalytic activity to decompose the phenol.

The electrochemical oxidation of HOPG (highly oriented pyrolytic graphite) was investigated in sulfuric acid solution at less than 1.0 V vs. NHE to clarify the oxidation mechanism of electrode material in polymer electrolyte fuel cells. It was found by surface analysis with X-ray photoelectron spectroscopy that several kinds of oxygenated functional groups were formed dependently on the potential. Furthermore, C-Br peaks were detected on the surface of HOPG after immersion in hydrobromic acid solution following holding at 1.0 V for 15 h. This suggests that lactones were formed in the course of electrochemical oxidation of HOPG.

A new way of preparation of TiO2/C photocatalyst by a pressure technique has been proposed. Hydrolysed titania TiO(OH)2(supplied by Chemical Factory Police in Poland) was used as a source of TiO2. TiO2/C was obtained by treating of TiO(OH)2with ethanol under pressure of 10 bar in a pressure reactor for 4 hours at a temperature of 180 °C. The building of carbon structures in the form of the alkene groups was proved by FTIR/DRS measurements, a new vibration in the region of 1520-1380 cm-1appeared on the FTIR spectrum of TiO2/C photocatalyst. The photocatalytic activity of TiO2/C photocatalyst was tested for the azo dyes decomposition (Reactive Red, Reactive Black and Direct Green) under either UV or artificial solar light irradiation. The decantability of the photocatalysts in dye solutions after the photocatalytic process was measured. The photoactivity of prepared TiO2/C was compared to the hydrolysed titania and a commercial TiO2Degussa P25. Introducing of carbon to TiO2improved both, the photoactivity of TiO2under UV irradiation and its ability for sedimentation. The both, hydrolysed titania and TiO2/C photocatalyst revealed a better photoactivity for dyes decomposition under artificial solar light irradiation than Degussa P25, Reactive Red spread on the surface of TiO(OH)2was decolourised after 4 hours of artificial solar light irradiation while on P25 surface this process took 72 hours.

Anatase type TiO2, ST-01 (Ishihara Sangyo Co. Ltd, Japan) was modified by mixing and heating with the powder of iron(II) oxalate in air and argon to obtain Fe-TiO2and Fe-C-TiO2photocatalysts, respecttively. TiO2as-received and the prepared photocatalysts were used for the phenol decomposition under UV irradiation with an addition of H2O2as a Fenton reagent. A different mechanism of phenol oxidation on Fe-TiO2and Fe-C-TiO2samples was observed: on the former, the radical reaction was dominant, whereas on the latter, a complex reaction with iron occurred. A different interaction of phenol molecules and its oxidation products with the surface of TiO2, Fe-TiO2and Fe-C-TiO2samples was observed by FTIR studies. Formed upon the phenol decomposition, hydroquinone is more likely adsorbed on the surface of Fe-C-TiO2than on TiO2or Fe-TiO2and is suggested that it affects the rate of phenol decomposition by the reduction of iron(III) to iron(II) and formation of a ternary HQ-Fe-H2O2complex.

Carbon-coated TiO2 photocatalysts were prepared by a simple heat treatment of the powder mixtures of anatase-type TiO2 with PVA at a temperature of 700 and 900 oC in a N2 atomosphere. Diffuse optical reflectance spectra for carbon-coated TiO2 showed the absorption edge for anatase structure clearly, overlapping with absorption due to coated carbon over whole range of wavelegth. These carbon-coated TiO2 photocatalysts had relatively high apparent BET surface area, from 50 to 170 m2/g, which suggested the formation of porous carbon layers, and showed relatively high adsorption of various pollutants, methylene blue (MB), reactive black (RB-5), phenol (Ph) and iminoctadine triacetate (IT), in water. Photocatalytic activity of carbon-coated TiO2 thus prepared was evaluated through the determination of the rate constant for the decomposition of different pollutants in water. Rate constant values were strongly depend on the pollutants, but their dependence on the crystallinity of TiO2 phase. The relations between adsorptivity and rate constant for four pollutants looked similar with each other, and the pollutants adsorbed in the larger amount was decomposed with the higher rate. Adsorptivity of carbon-coated TiO2 photocatlysts was determined and discussed on the relations to BET surface area, amount of carbon coated and also rate constant k for the decomposition of MB, RB5, Ph and IT. Adsorptivity of carbon-coated catalysts depends strongly on the adsorbate (pollutant) but also on the surface nature of carbon layer on TiO2 particles. The relations between adsorptivity and rate constant k for four pollutants looked similar, suggesting that the pollutant adsorbed in the larger amount being decomposed with the higher rate.

Carbon-coated TiO2 photocatalysts were prepared by a simple heat treatment of the powder mixtures of anatase-type TiO2 with PVA at a temperature of 700 and 900 oC in a N2 atomosphere. Diffuse optical reflectance spectra for carbon-coated TiO2 showed the absorption edge for anatase structure clearly, overlapping with absorption due to coated carbon over whole range of wavelegth. These carbon-coated TiO2 photocatalysts had relatively high apparent BET surface area, from 50 to 170 m2/g, which suggested the formation of porous carbon layers, and showed relatively high adsorption of various pollutants, methylene blue (MB), reactive black (RB-5), phenol (Ph) and iminoctadine triacetate (IT), in water. Photocatalytic activity of carbon-coated TiO2 thus prepared was evaluated through the determination of the rate constant for the decomposition of different pollutants in water. Rate constant values were strongly depend on the pollutants, but their dependence on the crystallinity of TiO2 phase. The relations between adsorptivity and rate constant for four pollutants looked similar with each other, and the pollutants adsorbed in the larger amount was decomposed with the higher rate. Adsorptivity of carbon-coated TiO2 photocatlysts was determined and discussed on the relations to BET surface area, amount of carbon coated and also rate constant k for the decomposition of MB, RB5, Ph and IT. Adsorptivity of carbon-coated catalysts depends strongly on the adsorbate (pollutant) but also on the surface nature of carbon layer on TiO2 particles. The relations between adsorptivity and rate constant k for four pollutants looked similar, suggesting that the pollutant adsorbed in the larger amount being decomposed with the higher rate.

The new photocatalysts were prepared from the commercial metatitanic acid (TiO(OH)2) by ethanol treatment. The photocatalytic activity of catalysts thus prepared was studied by degradation of phenol and dyes (Reactive Red (monoazo dye) Direct Green (polyazo dye) in water under artificial solar light irradiation. Introduction of carbon-containing species to the TiO2was identified from the FTIR/DRS spectra (new bands in the regions 3100-2800 cm-1and 1750-1400 cm-1). With increasing temperature through ethanol carbonisation, the rate of photodegradation of phenol under artificial solar light irradiation increased and the turbidity of the solution insignificantly decreased. On the UV-Vis/DR spectra of the TiO2/C photocatalysts, the decrease in reflectance in the visible light region was observed. Absorption of visible light by TiO2/C photocatalysts thus prepared can enhance their activity under solar light.

Starting materials such as Ti4O7were mixed with PVA powders in various mass ratios and then heated up to different temperatures from 900 °C in Ar. Fine particles of photocatalytic Ti4O7were coated by carbon, and reduced phases, such as Ti5O9were formed through interaction between Ti4O7and coated carbon. The photocatalytic activity was evaluated from the decomposition of iminoctadine triacetae (IT) in aqueous solution under visible light or UV irradiation. Commercial grades of anatase (ST-01), and commercially available Ti4O7were employed as reference materials. Under UV irradiation, the carbon-coated Ti4O7and Ti5O9were confirmed to have photocatalytic activity, though a little lower than that of anatase (ST-01). However, carbon-coated Ti4O7and Ti5O9were photoactive even under visible light, whereas anatase ST-01 was inactive. On comparison of Ti4O7and Ti5O9with and without carbon coating under irradiation of visible light, it was confirmed that Ti4O7and Ti5O9with carbon-coating had a higher photocatalytic activity than uncoated oxides.

In the impact of floors, sound transmission through walls, and structure-borne sound transmission in buildings, there is a possibility of improving the insulation by restricting the air particle motion at the interface of the vibrating surface and the air. One of the practical ways for realizing this condition is by subdividing the air layer at the interface in the direction parallel to the radiating surface. This novel method for noise control has an attractive simplicity and a real practical benefit. In this paper, the mechanism, causing this effect, is discussed using analytical models of acoustic radiation and sound transmission. As a result of this investigation, it is seen that the effect of this method is characterized by reduction of acoustic radiation at low frequencies near and below the critical frequency of coincidence. The method is validated experimentally.

Laser-beam-intensity fluctuations between an uplink (ground to satellite) and a downlink (satellite to ground) are described. The dependence of the beam radius on log-intensity variance in the uplink and the dependence of receiving-aperture diameter on the log-intensity variance in the downlink using a known theory were calculated. Statistical analysis of the experimental data on the laser links was performed, and high correlation coefficients of 0.94 between the normalized intensity variances of the uplink and those of the stellar scintillation were obtained. The beam-pointing error in the satelliteborne laser transmitter chiefly caused fluctuations in the downlink.

When a sound source is located near a large plane-surface reflector, the total acoustic power radiated from the source including the reflection depends on the source position. Interference is the cause of this phenomenon, and the musical instruments for bass sound are particularly influenced. The surface diffusion treatment of the stage reflectors may be a solution for improving the problem. In this paper, from the viewpoint of acoustic power from the stage area to the audience area, the effect of surface diffusion of a stage rear-wall is examined by using an analytical model of 2 and 3-dimensional wave theory. As a result of some numerical examples, it is shown that a rear wall tilted more than right angles has a potential of improving the effect.

A method that uses two quadrant detectors (QDs) for sensing wave-front tilt is described. The detectors are set at the front and back of the focal plane of the focusing optics. When the intensity distribution at the aperture of a telescope is not uniform because of atmospheric turbulence, the wave-front tilt can be measured more accurately with our two-QD method than with a conventional single-focal-plane QD. We proved this method to be effective by using it for fixed-star observation. Application of the method to a ground-to-satellite laser beam pointing system showed that it increases the intensity of the laser beam that is transmitted to a satellite.

Carbon coating of photocatalytic anatase-type TiO₂ powders was successfully carried out by heating a powder mixture of poly(vinyl alcohol) and TiO₂ under N₂ gas flow at temperatures above 700 °C. All particles of TiO₂ were covered by a carbon layer and looked black. For methylene blue (MB) in aqueous solution, carbon-coated anatase powders thus prepared showed marked adsorption and decomposition under UV irradiation and were confirmed to keep almost the same photoactivity as that without any carbon coating. Carbon coating of anatase-type TiO₂ was found to give different merits for photoactive performance; suppression of phase transformation from anatase to rutile at high temperatures, quick adsorption of MB into the carbon layer, decomposition of adsorbed MB by TiO₂ and prevention of the interaction of TiO₂ with binder resin. Repeated cycles of adsorption and decomposition of methylene blue in aqueous solution were experimentally confirmed.

We measured the characteristics of a quadrant-type avalanche photodiode (APD). Its transition region between the adjacent cells had a narrow width of 35 m. As the multiplication factor of the quadrant APD was limited by the variety of that among the quadrant cells, the maximum multiplication factor was about 30. We investigated the performance on applying the quadrant APD to a laser tracking system. A noise-equivalent angle of less than 1 rad (rms) was achieved at a received optical power of more than 4 pW. The quadrant APD compared favorably with a photodiode quadrant detector when the received power was less than 100 pW. © 2002 Society of Photo-Optical Instrumentation Engineers.

A technique for transmitting a narrow laser beam from a ground station to a satellite has been developed. The principle of pointing a laser beam to a distant target in a scattering medium by use of a backscattered laser beam image is described. We calculated the intensity distribution of the image by using a typical model of atmospheric coefficients. The method was applied to transmit a laser beam from a ground station to Engineering Test Satellite-VI. The accuracy of pointing the laser beam to the satellite was approximately 10 µrad in this experiment.

The sorption behaviors of four kinds of heavy oils into exfoliated graphites with different bulk densities were studied. The maximum sorption capacity of an exfoliated graphite with a bulk density of 6 kg/m3was found to be suprisingly high, 86 g of A-grade heavy oil and 76 g of crude oil per 1 g of exfoliated graphite, respectively, and also its sorption occured very rapidly, i.e. within 2 min. Sorption capacity was found to depend strongly on the bulk density and pore volume of the exfoliated graphite and the time it took to reach maximum sorption, as well as sorption capacity, as an exfoliated graphite depended strongly on the grade of heavy oil. Heavy oils sorbed into the exfoliated graphite could be recovered either by a simple compression or suction filtration with a recovery ratio of 60–80%. Recovered oils showed no difference in molecular weight and hydrocarbon constituent from the original. No increase of the water content in the recovered oils was detected, suggesting preferential sorption of heavy oil into exfoliated graphite. This result indicates clearly that the oils recovered from the exfoliated graphite can be recycled. From the present work, exfoliated graphite with low bulk density is a promising material for the sorption and recovery of spilled heavy oil.

ZnO thin films were prepared on silicon substrate with Pt electrode by the sol-gel processing using Zn alkoxide solution prepared from Zn(NO3)2·6H2O and 2-methoxyethanol. FT-IR spectroscopy showed the presence of Zn species in the alkoxide, with methoxyethoxide and nitrato groups as coordination ligands, indicating formation of Zn(NO3)(OCH2CH2OCH3). Smooth and homogeneous thin films were obtained by heat treating coating gel films in the temperature range from 250 to 500°C. The ZnO thin films exhibited a preferred growth of crystals with c-axis perpendicular to the Si substrate surface when fired at 250°C. It was discussed that the presence of nitrogen atoms in precursors had affected the phase development of crystals and was the basis of the structural relaxation for crystallization at low temperature.

(Ba0.92,Ca0.08)(Ti0.92,Zr0.08)O3thin films were prepared from Ba-Ti and Ca-Zr precursors by sol-gel processing. Polymerizable solutions containing Ba-Ti and Ca-Zr, respectively, were newly synthesized. Decomposition of the starting compounds and crystallization behavior of the film were examined by using TG/DTA and XRD. Microstructure of thin films was observed by using SEM. Polycrystalline (Ba0.92,Ca0.08)(Ti0.92, Zr0.08)O3films obtained by firing at 800°C were dense with fine grains. The thin films showed a dielectric constant of 1200 and dielectric loss of 0.5%.

The sol-gel processing was applied to the fabrication of PbTiO3fibers. Pb(CH3COO)2·3H2O and Ti(OC3H7i)4were refluxed with stirring in 2-methoxyethanol to form Pb-methoxyethoxide and Ti-methoxyethoxide, respectively, followed by mixing with stirring in 2-methoxyethanol to form Pb−Ti double alkoxide. The hydrolysis and polycondensation reaction of this double alkoxide gave polymerized products, and as a result the viscosity of the solution increased, suggesting that linear polymers were produced through the hydrolysis and polycondensation reaction. Homogeneous PbTiO3gel fibers were drawn from the spinnable viscous solutions, which were wellcrystallized into perovskite type PbTiO3at 650°C. The heat-treated fibers were a few centimeters long and from 10 to 100 μm in diameter. The fiber was made up of extremely uniform grains. Electron diffraction revealed a preferred growth of (101) planes along the fiber axis, which might be due to the linear molecular characteristics of the alkoxide.

The sol-gel processing was applied to the fabrication of PbTiO3fibers. Pb(CH3COO)2· 3H2O and Ti(OC3H $$_7^i $$ )4were refluxed with stirring in 2-methoxyethanol to form Pb-methoxyethoxide and Ti-methoxyethoxide, respectively, followed by mixing with stirring in 2-methoxyethanol to form Pb-Ti double alkoxide. The hydrolysis and polycondensation reaction of this double alkoxide gave polymerized products, and as a result the viscosity of the solution increased, suggesting that linear polymers were produced through the hydrolysis and polycondensation reaction. Homogeneous PbTiO3gel fibers were drawn from the spinnable viscous solutions, which were well-crystallized into perovskite type PbTiO3at 650°C. The heat-treated fibers were a few centimeters long and from 10 to 100 μm in diameter. The fiber was made up of extremely uniform grains. Electron diffraction revealed a preferred growth of (101) planes along the fiber axis, which might be due to the linear molecular characteristics of the alkoxide.

We investigated the oxygen electrode reactions (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)) of a pyrochlore-type metal oxide containing Bi and Ru (BRO), for aqueous air batteries. Here, we report the correlation between the calcination temperature of BRO and its catalytic activity in a KOH aqueous solution. It was found that the number of oxygen vacancies of BRO increased and the Tafel slopes for the ORR and OER decreased with an increase in the calcination temperature. The results of this study suggest that the oxygen vacancies of BRO are one of the factors that determine the catalytic activity for not only the ORR but also the OER.