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Biodiesel was efficiently produced from biomass fatty acids using renewable gas H2 and a reusable heterogeneous catalyst under low-energy-consumption microwave conditions. As the decarboxylation of...

Permittivity measurement and microwave heating characteristics of rod-shaped SiC (fragmented SiC fiber) mixed with SiO2 or Al2O3 were investigated, comparing with the mixtures of other two kinds of SiC materials. Rod-shaped SiC mixtures had larger permittivity (both real and especially imaginary parts) than the other SiC mixtures, and a broad peak of loss factor (er”) appeared around 1 GHz. Effective permittivity of mixtures was not successfully fitted by Maxwell-Garnett mixing law to the rod-shaped SiC mixtures but well fitted to other kinds of SiC mixtures. The microwave heating ability of rod-shaped SiC mixtures were much superior to that of other SiC mixtures, as expected from the larger loss factors. However, differences were observed between the mixture of rod-shaped SiC with SiO2 and with γ-Al2O3 in heating behavior and in the mixture permittivity. Interactions of the rod SiC are considered different between SiO2 and γ-Al2O3 and influenced the experimental heating data.

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders completely. In 2006, one-meter-long crack was detected in Yamazoe Bridge. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In previous studies, we investigated fatigue cracking behavior through fatigue tests using small girder specimens with web penetration details and effects of large attachment retrofitting methods against fatigue cracking in web penetration details through fatigue tests using a large girder specimen with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. However these methods cannot prevent fatigue crack initiation perfectly. In this study, we investigate effects of weld bead removal and small angle steel attachment retrofitting method against fatigue cracking in web penetration details through fatigue tests using a large girder specimen. As a result, it has been verified that weld bead removal and small angle steel attachment method can prevent fatigue crack initiation perfectly in the web penetration details with a slot.

SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased, in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 &deg, C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients.

We achieved the lowest-ever transmission losses of 0.1419 dB/km at 1560 nm wavelength and 0.1424 dB/km at 1550 nm in a Ge-free silica-core optical fiber. It was an improvement by 4 mdB/km from the previous record realized in 2015. The Ge-free silica core included fluorine co-doping, which helps to reduce disorder in the microscopic glass network structure that causes Rayleigh scattering loss without a significant increase in waveguide imperfection loss. A two-layered polymer coating with an inner layer having lower elastic modulus than before also contributed to the ultralow loss without influence of microbending loss increase even with an enlarged effective area of 147 μm2. The present fiber with ultralow loss and a large effective area benefits an ultralong haul optical transmission system including transoceanic submarine cable systems. We estimate system performance based on the fiber figure of merit theory that the present fiber enables a 0.10 bit/s/Hz increase in spectral efficiency or 7% reduction in the number of repeaters, compared to the previous record-loss fiber.

Single crystal growth of ScAlMgO4 boules with 10 mm up to 4 in. (c.a. 101.6 mm) in diameter by Czochralski technique was demonstrated. Some high quality ScAlMgO4 single crystal boules with 2-inches (c.a. 50.8 mm) in diameter were successfully grown without dislocation, which was revealed by X-ray rocking curve and X-ray topography measurements for the c-plane wafers. After a GaN template was formed on a substrate cut out from a grown ScAlMgO4 boule by using metalorganic vapor phase epitaxy, a thick GaN film was epitaxially grown on the template using hydride vapor phase epitaxy (HVPE). At the cooling stage after the growth in the HVPE process, the thick grown GaN film was separated by itself from the ScAlMgO4 substrate due to high cleavability of ScAlMgO4, which makes it possible the reuse of the substrate. The free-standing GaN grown on the reused ScAlMgO4 substrate showed the same quality as a GaN fabricated on a fresh ScAlMgO4 substrate. The reuse of ScAlMgO4 substrates is beneficial for saving the GaN films fabrication cost. The fabrication of a free-standing GaN substrate with 2 in. in diameter and 1 mm in thickness on ScAlMgO4 substrates was demonstrated to be more high-yield than the fabrication on a sapphire substrate. The growth method shown in this study is very promising, and it opens an efficient way to obtain GaN free-standing wafers and to reduce the production cost of GaN wafers.

X-ray diffraction analysis through high-resolution X-ray rocking curve measurement and X-ray topography was performed on Czockralski (CZ) -grown ScAlMgO4 (SAM) substrates. An extremely narrow rocking curve width of 0.002° (7.2 arcsec) was obtained, and the three-dimensional (3D) configuration of dislocations in the interior of the SAM crystal structure was analyzed through 3D section topography. Burgers vectors of dominating dislocations with slip planes of (0001) were determined to be parallel to the a-axis of the SAM crystal, and the dislocations were found to form clusters.

High-voltage silicone rubber composite insulators are widely used for outdoor insulation in power transmission lines. Silicone rubber, which is used as a housing material, gradually degrades with long-term use in the field. Therefore, to accurately determine the lifetime of composite insulators, it is essential to evaluate this degradation. This paper describes the results of depth profiling, which shows the change in the chemical composition caused by degradation, using laser-induced breakdown spectroscopy (LIBS). A remote LIBS system was constructed for application in in-situ degradation diagnostics. Field-aged insulators were irradiated with second harmonic Nd:YAG laser pulses at a distance of 10. The emission from the plasma was received by a telescope, and a spectroscopic analysis was performed. Energy dispersive X-ray spectroscopy (EDX) was performed for a comparative study. The emission intensity ratio of silicone to aluminum, which forms an alumina trihydrate filler, decreased by approximately 30% at the degraded surface compared to the undegraded bulk. A reduction in silicones at the degraded surface up to a depth of 300 was confirmed by LIBS and EDX measurements. These results show that remote LIBS using the ratio of silicone to aluminum as an index is a promising method for the in-situ diagnostics of composite insulators.

The joining of Al2O3 rods using SiC particles in a microwave field was examined. SiC with high microwave absorption characteristics is coated on the fracture surface of Al2O3 rods. Then, microwave irradiation is performed using a 2.45 GHz single-mode cavity and the Al2O3 rods are rapidly joined. Energy dispersive X-ray spectroscopy reveals that the substance generated on the joining surface comprises Al and O. It is believed that the SiC interacts with the microwave to generate microwave plasma and that the plasma melts the Al2O3 rods. Thus, the matrix melts and the fracture surfaces are joined.

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In a previous report, we investigated the stress distributions around web penetration details, and fatigue cracking behavior, using steel girder specimens with web penetration details. In this study, we investigate effects of retrofitting methods against fatigue cracking in web penetration details through fatigue tests using large girder specimens with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. Principal results obtained through this study are as follows: (1) Weld toe grinding can extend fatigue life more than 5 times, (2) Two-face attachment can extend fatigue life more than 10 times, and (3) Two-face attachment with weld toe grinding can extend fatigue life more than 25 times.

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties. In this study, we investigate stress reduction effects of three face attachment retrofit through fatigue tests using a large girder specimen with web penetration details where cross beam lower flanges are connected to the lower surface of a slot by welding. As a result, there is very little difference between two and three face attachments about stress reduction effects, while they are more effective than one face attachment. The upper side attachment is more effective than the lower side attachment, while both side attachment is best. Two and three face both side attachments can reduce about 40% of stress concentration, while two and three face upper side attachments can reduce 50– 60%.

MgtE is a Mg2+ channel conserved in organisms ranging from prokaryotes to eukaryotes, including humans, and plays an important role in Mg2+ homeostasis. The previously determined MgtE structures in the Mg2+-bound, closed-state, and structure-based functional analyses of MgtE revealed that the binding of Mg2+ ions to the MgtE cytoplasmic domain induces channel inactivation to maintain Mg2+ homeostasis. There are no structures of the transmembrane (TM) domain for MgtE in Mg2+-free conditions, and the pore-opening mechanism has thus remained unclear. Here, we determined the cryo-electron microscopy (cryo-EM) structure of the MgtE-Fab complex in the absence of Mg2+ ions. The Mg2+-free MgtE TM domain structure and its comparison with the Mg2+-bound, closed-state structure, together with functional analyses, showed the Mg2+-dependent pore opening of MgtE on the cytoplasmic side and revealed the kink motions of the TM2 and TM5 helices at the glycine residues, which are important for channel activity. Overall, our work provides structure-based mechanistic insights into the channel gating of MgtE., MgtE is a magnesium-selective ion channel whose gating is regulated by cytoplasmic magnesium concentration; this cryo-EM study reveals how MgtE undergoes magnesium-dependent structural changes to open the pore on the cytoplasmic side.

We investigated the performance of electric-field-induced second-harmonic generation (E-FISHG) by spectroscopic measurement using high-intensity femtosecond laser pulses. The second-harmonic intensity increased quadratically versus the applied electric field, as expected from the theory, up to 15 kV/cm with the laser energy up to 2.5 mJ, which is times higher than the observable optical breakdown threshold. In addition, when the laser energy was 2.8 mJ, times signal intensity at 0.23 mJ was obtained. These results suggest that the electric-field measurement by E-FISHG with high-intensity second harmonics is expected by using high-intensity laser pulses above the observable optical breakdown threshold. Spectroscopic measurement shows no E-FISHG of white light generated by self-phase modulation in laser-induced filament.

Recently, the microwave well absorber goes noticed as a heating aid to establish a microwave chemical plant. We determine the mechanism of the rapid and selective heating of magnetic conductive particles by electric and magnetic microwave fields. Furthermore, we investigate the dependencies of the Curie temperature of NixZn(1−x)Fe2O4 powders on their heating behaviors by employing a conventional microwave oven. In these experiments, the maximum microwave heating temperature increases with the Curie temperature of ferrites. To investigate the dependence of the microwave magnetic field strength on the heating behavior, we focus a pure magnetic field separated from 2.45 GHz microwaves onto these ferrites, and the magnetic field enhanced by a single-mode cavity is used to heat the ferrites at higher Curie temperatures. Our results indicate that there are two types of energy interactions between the ferrites and the microwave magnetic field with two different mechanisms: magnetic loss and eddy current heating. Furthermore, the heating performance of the ferrites as microwave absorbers is evaluated in comparison with SiC, which is a typical microwave absorber used in microwave processing. We believe that our findings can contribute to further advancements in microwave chemistry and related fields.

Two dimensional (2D) materials, such as graphene and transition metal dichalcogenides, are of potential interest from both exploratory research and application perspectives. Here we discuss the potential of bright field transmission electron microscopy (BFTEM) for quantitative mass thickness mapping of ultra thin samples illustrated using graphene [1, 2]., Proceedings of Microscopy & Microanalysis 2018, Aug 5-9, 2018, Baltimore, Maryland

Visualization of macromolecular structures is essential for understanding the mechanisms of biological functions because they are all determined by the structure and dynamics of macromolecular complexes. Electron cryomicroscopy (cryoEM) and image analysis has become a powerful tool for structural studies because of recent technical developments in microscope optics, cryostage control, image detection and the methods of sample preparation. In particular, the recent development of CMOS-based direct electron detectors with high sensitivity, high resolution and high frame rate has revolutionized the field of structural biology by making near-atomic resolution structural analysis possible from small amounts of solution samples. However, for some biological systems, it is still difficult to reach high resolution due to somewhat flexible nature of the structure, and a complementary use of cryoEM with X-ray crystallography is essential and useful to gain mechanistic understanding of the biological functions and mechanisms. We will describe our strategy for the structural analyses of actin filament and actomyosin rigor complex and the biological insights we gained from these structures.

We investigated experimentally the change in permeability in three different types of soft rocks including mudstone, sandstone, and tuff from the Fureoi and Takinoue formations, which are representative of the CCS demonstration site at Tomakomai in Japan, and another type of mudstone from the Besho Fm. (B-M). Permeability during deformation, shear fracturing, and post-failure slipping is estimated from measured flow rate and differential pore pressure. In addition, the morphologies of the shear fracture zones were examined using the X-ray CT scanning technique. All the samples exhibit typical brittle-fracturing behaviors, except for the B-M sample which does not show a major shear fracture. During the fracturing process, the permeability increased by one to three orders of magnitude. Further changes in the post-failure slipping and stress relaxation regimes show strong dependence on the type of rocks. Observed changes in permeability can be interpreted as results of fracturing creation, shear zone smoothing, closure and reactivation of fractures under different stress regimes. [doi:10.2320/matertrans.M-M2015802]

Lowest-ever 0.1419-dB/km loss at 1560-nm wavelength was realized in a silica-core fiber with 1290-°C low fictive temperature, 147-μm2 large effective area and low microbending loss due to soft primary coating.

The penetration profile of chlorine in a reinforced concrete (RC) specimen was determined by laser-induced breakdown spectroscopy (LIBS). The concrete core was prepared from RC beams with cracking damage induced by bending load and salt water spraying. LIBS was performed using a specimen that was obtained by splitting the concrete core, and the line scan of laser pulses gave the two-dimensional emission intensity profiles of 100 × 80 mm2 within one hour. The two-dimensional profile of the emission intensity suggests that the presence of the crack had less effect on the emission intensity when the measurement interval was larger than the crack width. The chlorine emission spectrum was measured without using the buffer gas, which is usually used for chlorine measurement, by collinear double-pulse LIBS. The apparent diffusion coefficient, which is one of the most important parameters for chloride penetration in concrete, was estimated using the depth profile of chlorine emission intensity and Fick's law. The carbonation depth was estimated on the basis of the relationship between carbon and calcium emission intensities. When the carbon emission intensity was statistically higher than the calcium emission intensity at the measurement point, we determined that the point was carbonated. The estimation results were consistent with the spraying test results using phenolphthalein solution. These results suggest that the quantitative estimation by LIBS of carbonation depth and chloride penetration can be performed simultaneously.

Threshold pressure Pcth (kPa), a parameter controlling rock's sealing performance in cases of CO2 geological sequestration, was studied in a supercritical CO2-water system under conditions of 1000 m depth (10 MPa and 40°C). With respect to correlation between Pcth and another important parameter of permeability, k (mdarcy), the closest-packing structure of spherical particles is defined theoretically as a line having slope of −0.5 on a double logarithmic plot. This study found this line by measuring Pcth of a capillary plate with known throat diameter as Pcth = 377.7 k– 0.5. This function is directly applicable to different depth and salinity conditions, although it requires minor correction at some temperature conditions. As a first step in determining the range of variation of rocks' Pcth and k from internal particle structures, we used sintered compacts of uniform spherical silica particles with diameters of 0.1–10 µm. Results show that measured values of sintered compacts were scattered around the closest-packing line, with the difference of packing state depending on different sintered additives and sintering temperatures. The change of packing state, occurring independently of resultant changes of porosity, varied sensitively according to Pcth. Therefore, Pcth is inferred to depend strongly on the local structure within rocks. The Knudsen number estimated for supercritical CO2 at 1000 m depth indicated that CO2 transmuted into a noncontinuum at k

Silicon is brittle and easily cracks even under a small load. The difficulty in shaping silicon has prevented breakthroughs in the mass production of silicon lenses for terahertz and infrared technology. We developed a novel method of deforming bulk single-crystal silicon into the required shape by one-shot pressing at a temperature just below the melting point of silicon, despite its brittleness and covalent nature, and realized the near-net shaping of the material into the plano-convex shape with the curvature radius R=7.5 mm for a infrared transmission lens. The crystallographic quality of the obtained lens could be improved by primary recrystallization. The simple method of 'pressing' will enable the mass production of not only silicon lenses but also lenses with a complex shape, such as aspherical lenses, and lens arrays by using dies with desired shape.

Crack propagation tests of lead-free solder were conducted at room temperature in air using center-notched plates under load-controlled conditions with three waveforms: triangular pp waveform having fast loading and unloading rates, cp-h waveform having a hold time under tension, and cc-h waveform having a hold time under tension and compression. The J integral was evaluated from load-displacement curves. For fatigue loading of pp waveform, the crack propagation rate was expressed as a power function of the fatigue J-integral range. The creep component due to the hold time greatly accelerated the crack propagation rate. The creep crack propagation rate was found to be a power function of the creep J integral range for each case of cp-h and cc-h waveforms. The creep crack propagation rate for cp-h waveform was higher than that for cc-h waveform. Displacement-controlled tests were also performed under four triangular strain waveforms: pp, cp, cc and pc. For the case of pp waveform, the crack propagation rate was also expressed as the same power function of the fatigue J integral range as in the case of load-controlled tests. The creep crack propagation rate was expressed as a power function of the creep J integral range for each case of cp, pc and cc waveforms. Microscopic observations were conducted to clarify micromechanisms of creep-fatigue crack propagation.

The atmospheric corrosion test and residual stress measurement were performed to evaluate the effect of laser irradiation on stress corrosion cracking (SCC) initiation. Second-harmonic Nd:YAG laser pulses (pulse width: 10 ns) were irradiated on a type-304L stainless-steel plate. The specimens were placed in a chamber at 353 K with RH=35% for the corrosion test. When laser energies were 30 and 300 mJ, cracks caused by SCC or pitting were observed on the surface of the specimens. The cracks were classified into two types on the basis of cumulative probability distribution; one of the types is related to the laser irradiation condition. The mean maximum crack depths were about 27 and 52 μm when laser energies were 30 and 300 mJ, respectively. These values were the same as the depth at which the tensile residual stress was induced from the surface of the specimen by laser irradiation. These results suggest that the maximum stress corrosion crack depth was caused by the tensile residual stress induced by laser irradiation, and that the crack stopped propagating when the crack depth was larger than several dozen μm in this test set. When laser pulses of 300 mJ energy were irradiated on the surface of the specimen by shot peening, the tensile stress was induced up to 20 μm from the surface, and the compressive stress was observed at a larger depth. These results show that the laser irradiation is less effective in obtaining tensile residual stress of the specimen compared to when laser pulses are irradiated on the specimen treated by shot peening. The depth of tensile stress obtained by laser irradiation is much shorter than that of compressive stress obtained by shot peening.

The drying up of the natural aggregate resources becomes the problem. The slag is an industrial by-product attracts attention as substitute aggregate. Ferro-nickel slag and copper slag are made a standard in Japan Industrial standard (JIS) as concrete aggregate. But the slag is hardly used on the construction site. The slag contains many type heavy metals. There is possibility that heavy metals in the slag retard cement hydration. Therefore, it is necessary to know the effect that heavy metals give on hydration of cement for utilization of slags as concrete aggregate. This paper shows retardation effects of four kinds of copper compounds and four kinds of zinc compounds on setting of mortar. Basic copper carbonate, copper (Ⅰ) oxide, copper (Ⅱ) oxide, copper (Ⅱ) sulfate pentahydrate, zinc oxide, zinc nitrate hexahydrate, basic zinc carbonate and zinc sulfide were used. It was found that setting retardation effect of each compound was different according to the form of the metal salt. Basic copper carbonate had highest effect of setting retardation in four kinds of copper compounds. And zinc oxide had highest effect of setting retardation in four kinds of zinc compounds. In addition, basic copper carbonate and zinc oxide had more high setting retardation effect. In this paper, it was shown that using basic copper carbonate and zinc oxide together caused 20 days delay of setting times of mortar.本研究では、塩基性炭酸銅、酸化銅（Ⅰ）、酸化銅（Ⅱ）および硫酸銅（Ⅱ）五水和物の4種類の銅化合物と、酸化亜鉛、硝酸亜鉛六水和物、塩基性炭酸亜鉛および硫化亜鉛の4種類の亜鉛化合物を用い、これらがモルタルの凝結特性に与える影響を検討した。その結果、同じ金属であっても塩の種類によって凝結遅延作用が異なること、塩基性炭酸銅と酸化亜鉛の凝結遅延作用が大きいことが分かった。また、塩基性炭酸銅と酸化亜鉛を併用することで、凝結の始発が最大で20日まで遅延することを示した。

We demonstrate the measurement of electrical properties of InN layers grown by RF-MBE using terahertz time-domain spectroscopic ellipsometry (THz-TDSE). Dependences of carrier density and mobility on InN film thickness are characterized using THz-TDSE. It is found that these electrical properties of the InN films are improved with the increase in the film thickness. Although the results obtained by Hall effect measurement also show the same tendency, the electrical properties of InN obtained by THz-TDSE is superior to those by Hall effect measurement. In addition, we also apply a two-layer model for THz-TDSE measurement to analyze the electrical properties of the bulk InN region and the surface electron accumulation layer independently. The mobility ranging from 50 to 140 cm2 V−1 s−1 are obtained for the surface electron accumulation layer of InN.

The ion-shadow method, an ion milling process using carbon particles as the mask material, is investigated as a means of preparing resistance random access memory (ReRAM) samples for in situ transmission electron microscopy (TEM). With a milling time of 1 hour (Ar+, 5 kV, 1 mA), multiple long needles (> 5 μm), on which there are miniaturized ReRAM devices comprising a ReRAM insulating layer sandwiched by two metallic electrodes, are formed on the substrate. Device sizes of up to several hundreds of nm are easily obtained with the method. The internal part of small devices (i.e., up to 100 nm) can be observed by TEM. Electrical measurements using an in situ TEM holder demonstrate that sufficient electric contact is obtained without any electric shortage between the electrodes due to re-deposition of milled material. The ion-shadow method is confirmed to be a quick and easy method suitable for in situ TEM experiments, especially for ReRAM devices which are highly susceptible to destruction during the switching operation.

In this study, hierarchical dual pore surfaces have been developed by two-step anodizing of aluminum. The first anodizing has been carried out at 390 V in 2 wt% citric acid, and then, the resultant anodic film has been dissolved to disclose the scalloped aluminum substrate with a cell size of ~900 nm. Subsequently, the second anodizing has been carried out at 25 V in 0.3 mol dm-3 sulfuric acid electrolyte to generate smaller nanopores. The size of nanopores has been further controlled by pore-widening treatment in 5 wt% phosphoric acid at 303 K. After coating with a fluoroalkyl phosphate monolayer to reduce the surface energy, the dual pillar surfaces with enlarged nanopores show super-repellency even for rapeseed oil as well as for water.

The purpose of this study is to examine the CO 2 sorption amount for Kimachi sandstone and Berea sandstone in water-saturated and air-dry states using pressure decay method (manometric method) at 50° and pressures of up to 20 MPa and to provide useful information for assessing the effect of water saturation state on sorption behavior of CO 2 in host reservoir rocks.

This study relates to retardation effects of some inorganic compounds on a set of cement mortar. Zinc oxide, Basic zinc carbonate, Copper（Ⅰ）oxide, Copper（Ⅱ）oxide and Basic copper carbonate were used as an inorganic set retarder. Additionally, mixtures of those compounds were tested to examine a combination effect. It was found that retardation effect of zinc compounds was bigger than that of copper compounds. The difference of retardation effect between the zinc compounds was small. And the difference of retardation effect between the copper compounds was also small. Using basic copper oxide and zinc oxide together made the retardation effect bigger than single use of zinc oxide or basic copper carbonate. Particularly, in the case of using a mixture of zinc oxide and basic copper oxide in the ratio of 2：1 by mass, setting of mortar was retarded up to about 10th day. Remixing the mortar shortened the set time, that is to say, decreased the retardation effect. Compressive strength of the mortar at the 28th day was comparable to that of plain mortar. It means those retarders do not affect on the compressive strength at such an age.本研究は無機化合物による凝結遅延効果についてモルタルを用いて検証を行ったものである。本研究では、無機化合物として試薬の酸化亜鉛、塩基性炭酸亜鉛、酸化銅（Ⅰ）、酸化銅（Ⅱ）、塩基性炭酸銅を用いた。その結果、酸化亜鉛と塩基性炭酸銅を質量比で2対1の割合で同時に添加することによってモルタルの凝結が10日程度まで遅延すること、また、凝結遅延させたモルタルを練直すことによって遅延時間が短縮されることがわかった。凝結遅延剤を添加したモルタルおよびそれらを練直して得たモルタルの圧縮強度は無添加のものと比較して材齢7日までは低いものの、材齢28日では同等であった。

Resistive random access memory (ReRAM) properties in which the resistance of the insulating material drastically changes by voltage application have recently attracted much attention. In this work, molybdenum oxide prepared by thermal oxidation of Mo films was studied to investigate its potential as a material exhibiting ReRAM switching. The samples oxidized between 400 and 600 °C were composed of MoO 3 and were switchable. Current-to-voltage curves, which were measured in air at room temperature by using a Pt–Ir probe as the top electrode, indicated the yielding of both the monopolar and bipolar switching properties. The resistance on-off ratio was between 10 and 10 2 .

In situ transmission electron microscopy (TEM) was carried out to investigate the dynamics of resistance switching in a solid electrolyte, Cu-Ge-S. By applying voltage to Pt-Ir/Cu-Ge-S/Pt-Ir, where Pt-Ir constituted the electrodes, a deposit containing conductive filaments composed mainly of Cu was formed around the cathode. As voltage continued to be applied, the deposit grew and finally narrow conductive filaments made contact with the anode. This corresponded to resistance switching from high- to low-resistance states (HRS and LRS). By alternating the voltage, the deposit contracted toward the cathode and detached from the anode. The resistance immediately changed from LRS to HRS. By applying voltage, the deposit containing Cu-based filaments grew and shrank, and resistance switching occurred at the electrolyte-anode interface. This conductive filament-formation model, which was recently reported, was experimentally confirmed with TEM through dynamic observations of the deposit-containing filaments.

Inside sewers, living sewage decomposes producing hydrogen sulfide, ammonia, methane etc. In the presence of these gases, hydrogen sulfide reduced by sulfate-reducing bacteria is oxidized into sulfuric acid by aerobic sulfur-oxidizing bacteria on the concrete surface, which severely deteriorates the concrete. When concrete is soaked in sulfuric acid, the relationship between the corrosion depth by sulfuric acid and the product of soaking time and concentrations of sulfuric acid are linear. The mortar which this relationship is clear is exposed in the sulfuric acid environment during a fixed period, and can be known corrosion depth, it is possible to presume the apparent concentrations of sulfuric acid. For that purpose, it is important that the relationship between the corrosion depth and the products of soaking time and concentrations of sulfuric acid hardly change by the age. In this paper, the effect of materials, mix proportions, curing method, curing period and curing temperature on the corrosion speed of mortar by sulfuric acid attack was investigated, and examined the suitable mortar for presumption of concentrations of sulfuric acid. As a result, it was desirable to use mortar with the crushed sandstone sand and cured in water above for 28 days after removing mold. The effect of type of cement, curing method and curing temperature are small.コンクリートを硫酸に浸漬した場合、硫酸浸漬期間と硫酸濃度の積と侵食深さの間には、線形関係が成り立つ。この関係が明らかなモルタルを硫酸環境で曝露し、一定期間で侵食された深さが分かれば、見かけの硫酸濃度を推定することが可能である。そのためには、硫酸浸漬期間と硫酸濃度の積と侵食深さの関係が材齢による変化の小さいものを用いることが重要である。本研究では、使用材料、配合および養生方法が、モルタル等の硫酸による侵食速度に及ぼす影響を調べ、硫酸の濃度推定に適切なモルタルについて検討を行った。その結果、細骨材に砂岩砕砂を用いたモルタルで、脱型後28日以上水中で養生を行うことが望ましいことが分かった。