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For a battery module where single cells are connected in series, the single cells should each have a similar state of charge (SOC) to prevent them from being exposed to an overcharge or over-discharge during charge–discharge cycling. To detect the existence of unbalanced SOC cells in a battery module, we propose a simple measurement method using a single-frequency response of electrochemical impedance spectroscopy (EIS). For a commercially available graphite/nickel-cobalt-aluminum-oxide lithium-ion cell, the cell impedance increases significantly below SOC20%, while the impedance in the medium SOC region (SOC20%–SOC80%) remains low with only minor changes. This impedance behavior is mostly due to the elementary processes of cathode reactions in the cell. Among the impedance values (Z, Z′, Z″), the imaginary component of Z″ regarding cathode reactions changes heavily as a function of SOC, in particular, when the EIS measurement is performed around 0.1 Hz. Thanks to the significant difference in the time constant of cathode reactions between ≤SOC10% and ≥SOC20%, a single-frequency EIS measurement enlarges the difference in impedance between balanced and unbalanced cells in the module and facilitates an ~80% improvement in the detection signal compared to results with conventional EIS measurements.

Achieving both the backbone order and solubility of π-conjugated polymers, which are often in a trade-off relationship, is imperative for maximizing the performance of organic solar cells. Here, we studied three different π-conjugated polymers based on thiazolothiazole (PSTz1 and POTz1) and benzobisthiazole (PNBTz1) that were combined with a benzodithiophene unit in the backbone, where PNBTz1 was newly synthesized. Because of the steric hindrance between the side chains located on neighboring heteroaromatic rings, POTz1 had a much less coplanar backbone than PSTz1 in which such a steric hindrance is absent. However, POTz1 showed higher photovoltaic performance in solar cells that used Y6 as the acceptor material. This was likely due to the significantly higher solubility of POTz1 than PSTz1, resulting in a better morphology. Interestingly, PNBTz1 was found to have markedly higher backbone coplanarity than POTz1, despite having similar steric hindrance between the side chains, most likely owing to the more extended π-electron system, whereas PNBTz1 had good solubility comparable to POTz1. As a result, PNBTz1 exhibited higher photovoltaic performance than POTz1 in the Y6-based cells: specifically, the fill factor was significantly enhanced. Our results indicate that the backbone order and solubility can be achieved by the careful molecular design, which indeed leads to higher photovoltaic performance.

During a severe accident (SA) such as the Fukushima Daiichi Nuclear Power Plant accident, fission products (FPs) can be retained on the surface of structural materials in reactors. Cesium (Cs) is a...

π-Conjugated polymers are important materials for organic photovoltaics. While search for new backbone systems is central to the development of π-conjugated polymers, side chain engineering is also imperative. Here, we synthesized two benzodithiophene-thiazolothiazole copolymers, PSTz1 and POTz1, where the side chain placement is different. Due to the less steric hindrance between the side chains, PSTz1 had a more coplanar backbone than POTz1. This led to significant differences in trend of the performance for the binary and ternary blend cells that used a fullerene (PC 71 BM) and/or a non-fullerene (ITIC) as the acceptor materials. Whereas PSTz1 showed higher photovoltaic performance in the PC 71 BM-based cell, POTz1 showed higher performance in the ITIC-based cell. Furthermore, in the ternary blend cell, whereas increase in the PC 71 BM content improved the photovoltaic performance for the PSTz1 system, it was detrimental to the performance for the POTz1 system. We believe that these results would be a good guideline for maximizing the performance of organic photovoltaics.

We analyzed edible potato starch and observed the interaction between its granular structure and water molecules. We studied the changes caused by gelatinization during heating and stirring using microscopy, micro‐FT‐IR spectroscopy, and X‐ray scattering techniques. A wide range of spatial scales was revealed using these various techniques. The rate of gelatinization varied significantly and was dependent on the starch concentration. The process of adsorption of water on starch molecules was studied using the humidity‐controlled FT‐IR spectroscopy technique. Furthermore, by comparing the X‐ray scattering profiles of dry and wet granules, the 9‐nm repeat “cluster” structure was studied. A gradual collapse of the granules occurred during the processes of heating and stirring. A clustered smectic structure and a smectic‐like structure were observed in the opaque gel after gelatinization. Upon further heating, a transparent gel was obtained after the melting of the cluster., We analyzed edible potato starch and observed the interaction between its granular structure and water molecules. A wide range of spatial scales was revealed using various techniques such as X‐ray scattering and FT‐IR measurements. We could succeed gelatinization and gelation process with a wide spatial scale.

Herein, we study the origin of differences in open-circuit voltage (VOC) for polymer:fullerene solar cells employing highly crystalline conjugated polymers (PTzBT) based on the same thiophene–thiazolothiazole backbone with different side chains. By analyzing the temperature dependence of VOC and cyclic voltammogram, we find that the difference in VOC originates in the different cascaded energy structures for the highest occupied molecular orbital (HOMO) levels in the interfacial mixed phase. Furthermore, we find that this is due to the stabilization of HOMO caused by the different branching of side chains on the basis of density functional theory calculation. Finally, we discuss the molecular design strategy based on side-chain engineering for ideal interfacial cascaded energy structures leading to higher VOC and photocurrent simultaneously.

Polymer-blend solar cells (all-PSCs) based on a copolymer of naphthodithiophene diimide and bithiophene (PNDTI-BT-DT) as a near-infrared absorber as well as an electron acceptor were fabricated in combination with PTB7 as an electron donor. Notably, the external quantum efficiency spectra of the all-PSCs demonstrated photoresponse up to 900 nm with the efficiency of 25% at 800 nm, which is much higher than that for the previously reported all-PSCs. Power conversion efficiency as high as 2.59% was achieved under the irradiation of simulated solar light (AM1.5, 100 mW/cm2). Both PNDTI-BT-DT and PTB7 formed a crystalline structure in the blend films similar to in the pristine films, leading to the efficient charge generation contributed from both polymers.

Thiazole has been less focused, compared to thiophene, as the building unit for π-conjugated polymers that are used in organic electronic devices despite its electron deficiency and ability to coplanarize the polymer backbone, which are crucial for design of such π-conjugated polymers. Here, we show that bithiazole dicarboxylate ester (BETz), which is quite easily synthesized, is a promising building unit for π-conjugated polymers. Copolymers based on BETz, having unsubstituted bithiophene and bithiazole as counits, indeed form highly crystalline structures in thin films, which is beneficial for semiconducting properties. Of particular interest is that the BETz-based polymers are found to show electron-transport property even though the lowest unoccupied molecular orbital (LUMO) energy levels are not very low, as they show ambipolar and unipolar n-channel behaviors depending on the counit in organic transistor devices. We believe that BETz allows us to design a wide variety of π-conjugated polymers that provide fascinating functions in organic electronic devices.

Field effect transistor (FET) biosensors are capable of detecting various biomolecules, although challenges remain in the detection of uncharged molecules. In this study, the detection of uncharged cortisol was demonstrated by interfacial design using a technique to immobilize target-bound aptamers. The target-bound aptamers, which formed a higher-order structure than target-unbound aptamers, expanded the distance between adjacent aptamers and reduced the steric hindrance to the conformational change. The density-controlled aptamers efficiently induced their conformational changes with the cortisol binding, which resulted in the improvement of the sensitivity of FET biosensors.

The control of three-dimensional (3D) geometrical shapes is one of important approaches that contribute the development of new functionalities in material science. We produced 3D Si pyramids with a...

Lithium-ion capacitors (LICs) are energy storage devices that bridge the gap between electric double-layer capacitors and lithium-ion batteries (LIBs). A typical LIC cell is composed of a capacitor-type positive electrode and a battery-type negative electrode. The most common negative electrode material, graphite, suffers from low rate capability and cyclability due to the sluggish kinetics of the Li+ intercalation/de-intercalation process. In this work, metal chloride-pillared graphite, which has recently attracted attention as high-rate LIB anodes, is applied as the negative electrode for LICs for the first time to overcome this drawback. It is shown that AlCl3-graphite intercalation compounds (AlCl3-GICs) with a wide interlayer spacing benefits faster Li+ diffusion. The low molecular weight and conversion reaction of the AlCl3 pillar further enhances the specific capacity per mass. An optimized LIC cell comprised of a AlCl3-GIC negative electrode and activated carbon as the positive electrode exhibited higher energy and power densities compared to LICs using graphite as the negative electrode, and displayed stable cycling performance with 85% capacity retention after 10,000 charge/discharge cycles. The AlCl3-GICs synthesized in this work displayed improved electrochemical performances and have the potential to replace the graphite electrode in conventional LICs.

Increasing photon harvest is an essential issue in improving the efficiency of organic photovoltaics. Here, we study ternary blend polymer solar cells that are composed of a thiazolothiazole-based crystalline semiconducting polymer and a fullerene derivative as the host binary system and a very small content of a series of narrow-band gap non-fullerene acceptors as the third-component sensitizer that is selectively located at the interface between the host donor and acceptor. Surprisingly, the cells give an external quantum efficiency in the sensitizer absorption range that is as high as that in the polymer absorption range despite the fact that the optimal sensitizer content is only 6 wt %, which is far smaller than the host polymer contents. This leads to significantly improved photocurrents and, in turn, high power conversion efficiencies relative to the binary blend cell. Such pronounced sensitization is found to originate in the markedly amplified sensitizer absorption owing to the optical interference effect of more than 300 nm-thick photoactive layers. In parallel, the ternary blend system realizes markedly reduced photon energy loss, which is also important for the power conversion efficiency improvement, and high thermal stability. With such excellent features, we believe that the sensitized ternary blend cells have exceptional possibilities and that exploring more well-matched material combinations would improve the performance further., 光干渉効果を利用し、低コストで有機薄膜太陽電池を飛躍的に高効率化することに成功. 京都大学プレスリリース. 2020-12-02.

Acrylic rubber (ACM) nanocomposites reinforced with cellulose nanocrystals (CNCs) were prepared and the properties were characterized. CNCs were produced by hydrochloric acid hydrolysis of microcry...

Recent developments in molecular doping technologies allow extremely high carrier densities in polymeric semiconductors, exhibiting great diversity because of the unique size, conformation, and steric effect of molecular dopants. However, it is controversial how steric effects can limit the doping efficiency and to what extent dopants can be accommodated in polymers. Here, we employ two distinct conjugated polymers with different alkyl side-chain densities, where polymers are doped via anion-change, allowing greater variation in the incorporation of molecular dopants having different electrostatic potentials and shapes. We characterize the doping efficiency with regard to steric effects, considering the unique void space in the conjugated polymers. Our study reveals that doping efficiency of polymers with sparse alkyl side-chains is significantly greater than that with dense side-chains. A closest-packed supramolecule is realized with a particular combination of a sparse polymer and a large dopant, giving rise to high conductivity, air stability, and remarkably high work function. This work provides a critical insight into overcoming steric effects in molecular doping. Anion-exchange doping allows high carrier densities in organic semiconductors but can be limited by host-guest steric effects. Here, these are analyzed, and high doping efficiency is realized for a specific combination of a polymer with sparse side-chains and a large dopant, forming a close-packed structure.

Sub-µm CaCO3 (calcite; CC) particles were converted to calcium monohydrogenphosphate dihydrate (DCPD) and hydroxyapatite (HAp) via soaking treatments in K2HPO4 solutions with varied pH (3–12) and concentrations (0.1–1.5 M) at 37°C for up to 10 days. DCPD was derived from the solutions with pH ≤ 6; while hollow HAp was yielded when pH ≥ 7 in assemblies of petal-like crystallites. Results of magic angle spinning (MAS) and cross-polarization magic angle spinning (CP-MAS) NMR studies have shown that the HAp lattice has only PO4 2− but no HPO4 2− at B (phosphate) sites. Trace amounts of CO3 2− have occupied both A (OH) and B (PO4) sites, and H2O is adsorbed on surface crystallites. The primary crystallite size of HAp derived from Scherrer equation increases quickly in a 12 h period and becomes gradually stable afterward. Samples of particles soaked within 3 h in a temperature range of 20–80°C were analyzed by X-ray diffraction. It is shown that the rate constant of 1 M solution is about an order of magnitude greater than that of 0.1 M solution and the apparent activation energy is 33 kJ/mol. In this work, the conversion of CC to HAp can be quantitatively controlled to solve the problem of slow degradation of HAp.

A focus characterization method using the intensity correlation of X-ray fluorescence is proposed, and demonstrated for the sub-micrometre focused X-ray free-electron laser beam at the SPring-8 Angstrom Compact Free Electron Laser., This paper proposes and demonstrates a simple method using the intensity correlation of X-ray fluorescence to evaluate the focused beam size of an X-ray free-electron laser (XFEL). This method was applied to the sub-micrometre focused XFEL beam at the SPring-8 Angstrom Compact Free Electron Laser, and the beam size evaluated using the proposed method was consistent with that measured using the knife-edge scan method. The proposed method is readily applicable to extremely small X-ray spots and can be applied for the precise diagnostics of sub-10 nm focused X-ray beams which have recently emerged.

The performance of desulfurization materials plays a key role in desulfurization technology. In this study, different types of manganese dioxide (MnO2) composites were prepared to improve desulfurization performance. These composites were characterized intensively via SEM, XRD, XPS, and BET. Desulfurization performance was measured through thermogravimetry (TG), and the desulfurization mechanism of different types of MnO2 composite was investigated. Results showed that the desulfurization performances of MnO2 composites are determined by the combined effects of the materials’ pore structure, specific surface area, active components and Mn valence contents. The desulfurization performances of high specific surface area MnO2 and porous MnO2 were enhanced on account of their excellent physical structures. The desulfurization performance of alkali metal additive LiOH doped MnO2 improved through the addition of active components. The desulfurization performance of bimetallic oxide MnO2/CeO2 improved through the synergistic effect of bimetallic oxides. The desulfurization performance of carrier type MnO2/NaY improved through the dispersion of MnO2 particles. Among the composites obtained, porous MnO2 revealed the best desulfurization performance, this composite demonstrated an average SO2 capture rate of 0.283 gSO2/gmaterial·h within the first hour of reaction, and its SO2 capture capacity was 0.633 gSO2/gmaterial.

The paper focuses on examining agreement of the adaptive smoothed particle hydrodynamics (ASPH) in the investigation of the sliding friction of silica at micronscale throughout observation of several friction characteristics. It is found that the ASPH approach well presents the friction of micronscale silica due to agreement of the friction coefficient and the applied load-friction coefficient relationship between the present results and the previously experimental reports. The shape of the particle modeled in the ASPH almost does not effect on the detected results for the hard system due to the very slight variation of the particles during the sliding. However, the variation of the particles can explain for the discrepancy between the stick time and the slip time and the unsharp change between the stick state and the slip one. The study is also extended for the contacts of the two sinusoidal rough surfaces and finds that the friction coefficient is almost independent of the wavelength while it linearly increases with the amplitude.

Aiming for the fine observation of fast physical phenomena such as phonon propagation and laser ablation, phase-contrast X-ray imaging combined with a crystal X-ray interferometer and the X-ray free-electron laser (XFEL) of the SPring-8 Angstrom Compact Free-Electron Laser has been developed. An interference pattern with 70% visibility was obtained by single-shot exposure with a 15 keV monochromated XFEL. In addition, a phase map of an acrylic wedge was successfully obtained using the fringe scanning method.

Focusing of an X-ray free-electron laser enables the production of ultrahigh-intensity X-ray pulses. X-ray nanobeams of a free-electron laser were generated using reflective focusing optics combined with speckle interferometry., Ultimate focusing of an X-ray free-electron laser (XFEL) enables the generation of ultrahigh-intensity X-ray pulses. Although sub-10 nm focusing has already been achieved using synchrotron light sources, the sub-10 nm focusing of XFEL beams remains difficult mainly because the insufficient stability of the light source hinders the evaluation of a focused beam profile. This problem is specifically disadvantageous for the Kirkpatrick–Baez (KB) mirror focusing system, in which a slight misalignment of ∼300 nrad can degrade the focused beam. In this work, an X-ray nanobeam of a free-electron laser was generated using reflective KB focusing optics combined with speckle interferometry. The speckle profiles generated by 2 nm platinum particles were systematically investigated on a single-shot basis by changing the alignment of the multilayer KB mirror system installed at the SPring-8 Angstrom Compact Free-Electron Laser, in combination with computer simulations. It was verified that the KB mirror alignments were optimized with the required accuracy, and a focused vertical beam of 5.8 nm (±1.2 nm) was achieved after optimization. The speckle interferometry reported in this study is expected to be an effective tool for optimizing the alignment of nano-focusing systems and for generating an unprecedented intensity of up to 1022 W cm−2 using XFEL sources.

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of light water reactor (LWR) under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation could elucidate two mechanisms for the gaseous iodine formation. One was the gaseous phase chemical reaction in Cs-I-O-H system at relatively high-temperature region, which led to gaseous iodine transport to the lower temperature region without any further changes in gas species due to the kinetics limitation effects. The other one was the chemical reactions related to condensed phase of CsI, namely those of CsI deposits on walls with surface of stainless steel to form Cs2CrO4 compound and CsI aerosol particles with steam, which were newly found in this study.

Coulombic efficiency (CE) has been widely used in battery research as a quantifiable indicator for the reversibility of batteries. While CE helps to predict the lifespan of a lithium-ion battery, the prediction is not necessarily accurate in a rechargeable lithium metal battery. Here, we discuss the fundamental definition of CE and unravel its true meaning in lithium-ion batteries and a few representative configurations of lithium metal batteries. Through examining the similarities and differences of CE in lithium-ion batteries and lithium metal batteries, we establish a CE measuring protocol with the aim of developing high-energy long-lasting practical lithium metal batteries. The understanding of CE and the CE protocol are broadly applicable in other rechargeable metal batteries including Zn, Mg and Na batteries. Coulombic efficiency (CE) has been frequently used to assess the cyclability of newly developed materials for lithium metal batteries. The authors argue that caution must be exercised during the assessment of CE, and propose a CE testing protocol for the development of lithium metal batteries.

In situ anatase thin film with high percentage exposure of {001} facet was fabricated on titanium substrate via one-step hydrothermal method at low temperature from the precursor solution of (NH4)2TiF6 and HF. Nano-inverted bipyramid arrays densely covered the whole surface on as-treated Ti substrate. The structural analysis clearly indicated that as-deposited thin film only consisted of anatase TiO2 single crystal with preferred oriented {001} facets. According to the XRD patterns of as-treated anatase thin film, the integral intensity ratio of (004) to (101) peaks was as high as 7.5 which was remarkably higher than the standard value 0.18. Based on the experimental results, the growth pattern and bonding strength of nano-structural array with high percentage exposure of anatase {001} facet on Ti substrate were discussed. The biocompatibility results demonstrated that MC3T3-E1 cells grown on the as-treated Ti sheet exhibited positive effect on the cell proliferation and significantly high gene expression of ALP, COL-1, BMP-2, OPN and RUNX2 due to its specific property of the surface. Hence, the in situ anatase thin film with high percentage exposure of {001} facet was expected to achieve satisfactory primary stability for osseointegration. In situ fabrication of anatase TiO2 nano-inverted bipyramid arrays with high percentage exposure of {001} facet

The interaction of cesium hydroxide and a calcium silicate insulation material was experimentally investigated at high-temperature conditions to evaluate the possibility of unprecedented cesium ret...

A large amount of cesium (Cs) chemisorbed onto stainless steel is predicted to be present especially in the upper region of reactor pressure vessel (RPV) during light water reactor severe accident. A chemisorption model was developed for estimation of such amounts of Cs for stainless steel type 304 (SS304) exposed to cesium hydroxide (CsOH) vapor. However, this existing chemisorption model cannot accurately reproduce experimental results and is considered not to be suitable for the estimation of the Cs-chemisorbed amounts under various conditions experienced in Fukushima Dai-ichi nuclear power station. Our recent laboratory study indicated that the surface reaction rate constant used in the exiting chemisorption model depended on both of silicon content in SS304 and concentration of gaseous CsOH as well as on temperature. Therefore, in this study, a modified Cs chemisorption model which accounts for these effects was constructed by combining penetration theory for gas-liquid mass transfer with chemical reaction and mass action law for CsOH decomposition at interface between gaseous and solid phases. As a result, it was found that the modified model was able to adequately describe effects on concentration of CsOH in gaseous phase and Si content in SS304 and more accurately reproduce the experimental data than the existing model.

The low temperature heat capacity of Cs2Si4O9, which is one of the cesium chemisorbed compounds onto stainless steel during severe accidents of the light water nuclear reactor, was experimentally d...

Inverted-type polymer solar cells with poly[naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole-5,10-diyl[3,4′-bis(2-butyloctyl)[2,2′-bithiophene]-5,5′-diyl]thiazolo[5,4-d]thiazole-2,5-diyl[3′,4-bis(2-butyloctyl)[2,2′-bithiophene]-5,5′-diyl]] (PTzNTz) have attracted attention because of their high power conversion efficiency and thermal stability. However, the internal deterioration mechanism has not yet been completely clarified. Here, we report operand electron spin resonance (ESR) spectroscopy of the highly durable PTzNTz polymer solar cells to investigate the mechanism of the device-performance deterioration at a molecular level. We identify the layer with accumulated charges in the PTzNTz cells by the analyses of light-induced components in the ESR spectra of the thin films and cells with PTzNTz. We observe the correlation between the increase in the number of spins and the decrease in the device performance. Notably, compared to the previously reported ESR studies of polymer solar cells, the PTzNTz solar cells have less charge accumulation and higher durability. This correlation holds even if another hole-transport layer of PTzNTz solar cells is utilized. The calculation with density functional theory is performed to analyze the charge-accumulation states in the cells. The present results are useful to develop further highly efficient and durable polymer solar cells.

A calcium silicate insulator material was investigated for its interaction with non-radioactive cesium at room temperature by batch-type adsorption experiments. An industrial-grade calcium silicate was weighted and ground into powder with an average size of 15.4 ± 0.1 μm, which was then placed into the polypropylene (PP) tubes containing cesium chloride aqueous solution. Cesium concentrations were range between 1.3×10-6–3.5×10-3 M. Adsorption kinetics of cesium was evaluated based on pseudo-first order and pseudo-second order models, while the adsorption isotherm was modeled using the Langmuir model and modified BET model. Physicochemical properties of calcium silicate before and after the adsorption was investigated using XRD, SEM/EDS, and FT-IR. Chemisorption was found as the underlying sorption process between calcium silicate insulator material and cesium.

Organic photovoltaics (OPVs) are a topic of significant research interest in the field of renewable energy as well as organic electronics. The crucial issue in OPVs is the improvement of the power conversion efficiency (PCE). In addressing this issue, one of the most important factors is the photon energy loss (Eloss), which is defined as the difference between the bandgap of the materials and the energy corresponding to the open-circuit voltage. Typically, the Eloss for OPVs is considerably larger than that for inorganic and perovskite photovoltaics, which has prevented OPVs from generating larger photovoltages. In parallel, reducing the Eloss for OPVs causes a loss of driving-force energy for charge generation, which is detrimental to the generation of photocurrent. Thus, OPVs have been facing a trade-off between photocurrent and photovoltage. However, a number of recently developed π-conjugated materials for use as p-type and n-type organic semiconductors have been shown to enable small Eloss values that are close to those for inorganic systems, simultaneously with efficient charge generation. Here, we summarize recent progress in π-conjugated polymers and molecules that enable small Eloss and high PCE at the same time. We hope that this review will be of help to chemists and materials scientists who are involved in the design of materials and blends with an eye toward highly efficient OPVs.

Small-bandgap π-conjugated polymers are an important class of materials possessing significant potential for their broad application in organic electronics. Incorporating a quinoid structure into the polymer backbone is a powerful strategy for reducing the bandgap. Although this also leads to high-lying HOMO energy levels, resulting in unstable polymers, the use of an electron-deficient quinoid building unit can bring about low-lying HOMO energy levels, thus stabilizing the polymer against oxidation. Recent efforts in molecular design and synthesis have produced a number of fascinating small-bandgap π-conjugated polymers based on quinoid structures, many of which have shown notable performance in organic electronic devices such as transistors and solar cells. This review covers the progress in small-bandgap quinoid-based π-conjugated polymers, focusing on a variety of electron-deficient quinoid building units. We highlight the properties of each quinoid building unit and the polymers along with their structural features and device performances.

Since the Fukushima Daiichi nuclear power plant accident, we have been developing a failure evaluation method that considers creep damage mechanisms using detailed three-dimensional finite element analysis model of lower head including penetration, stub tubes, and weld parts, etc., for the early completion of the decommissioning of the nuclear power plants in Fukushima Daiichi. For the finite element analysis, we have been obtaining material properties for which no data are provided in existing databases or in the literature. In particular, creep data corresponding to the high temperature region near the melting point of materials is important in evaluating creep deformation under severe accident conditions. In this study, we obtained the uniaxial tensile and creep properties for low-alloy steel, stainless steel, and Ni-based alloy. In particular, creep test data with long rupture times at high temperatures are expanded using a tensile test machine that can measure the elongation of test specimens in a noncontact measurement system. The parameters related to the failure evaluation were improved on the basis of the expanded creep database.

Silica nanoparticle growth during the polymerization of silicic acid in saline geothermal brine from the Yamagawa geothermal power station, Japan, was examined using dynamic light scattering (DLS). Two types of polysilicic acid particles (large and small) were found to grow simultaneously after vapor–brine separation at the surface. The DLS results seemed to indicate that the average particle size increased over the initial 70 min and then decreased, however this is most likely due to the larger particles settling out. The small particles gradually increased to 200 nm over 180 min. As deduced from the change in the numbers of the two types of polysilicic acid particles, the small particles were absorbed by the large particles.

This paper presents our investigation on cesium and iodine revaporization from cesium iodide (CsI) deposits on stainless steel type 304L, which were initiated by boron and/or steam flow. A dedicated basic experimental facility with a thermal gradient tube (TGT) having a temperature range of 1000–400 K was used for simulating the phenomena. In the absence of boron, it was found that the initially deposited CsI at 850 K could be revaporized as CsI vapor/aerosol or reacted with the carrier gas and stainless steel (Cr2O3 layer) to form Cs2CrO4. The latter mechanism consequently released gaseous iodine that was later accumulated downstream. After introducing boron to the steam flow, a severe revaporization occurred. This, in addition to the revaporized CsI vapor/aerosol, was caused by cesium borate (Cs2B4O7 and CsB5O8) formation, which then largely released gaseous iodine that was capable of reaching the TGT outlet (

In this contribution, design and synthesis of various π-conjugated building unit based on naphthobisthiadiazole heteroaromatic ring are presented. These units are successfully incorporated into donor polymers and an acceptor molecule, which are found to have high π-π interactions to form well-ordered structures in the thin film. These materials therefore function well in organic photovoltaic cells. The structure-properties relationships are also discussed in depth.

The present study uses the smoothed particle hydrodynamics (SPH) and discrete element method (DEM) coupling to investigate influence of the hexagonal boron nitride (hBN) particles on friction of the elastic coarse-grained micronscale iron. The hBN lubricant particles significantly improve the friction performance of iron in various simulation behaviors. The particle size, the air/water background containing the particles, and its temperature result in reduction of the friction coefficient. The surface mending, the protective film, and the energy dissipation are the main mechanisms related to the friction reduction. Additionally, it is worthy to note that the static friction and the kinetic friction can be clearly observed by this elastic coarse-graining.

In order to avoid the stress shielding phenomenon in orthopedic bionic bone implantation, it is necessary to consider the design of mechanical compatible implants imitating the host bone. In this study, we developed a novel cancellous bone structure design method aimed at ensuring the mechanical compatibility between the bionic bone and human bone by means of computer-aided design (CAD) and finite element analysis technology (specifically, finite element modeling (FEM)). An orthogonal lattice model with volume porosity between 59% and 96% was developed by means of CAD. The effective equivalent elastic modulus of a honeycomb structure with square holes was studied by FEM simulation. With the purpose of verifying the validity of the cancellous bone structure design method, the honeycomb structure was fabricated by selective laser sintering (SLS) and the actual equivalent elastic modulus of the honeycomb structure was measured with a uniaxial compression test. The experimental results were compared with the FEM values and the predicted values. The results showed that the stiffness values of the designed structures were within the acceptable range of human cancellous bone of 50–500 MPa, which was similar to the stiffness values of human vertebrae L1 and L5. From the point of view of mechanical strength, the established cellular model can effectively match the elastic modulus of human vertebrae cancellous bone. The functional relationship between the volume porosity of the nylon square-pore honeycomb structure ranging from 59% to 96% and the effective elastic modulus was established. The effect of structural changes related to the manufacture of honeycomb structures on the equivalent elastic modulus of honeycomb structures was studied quantitatively by finite element modeling.

In this work, we present a powdered Si-O-C composite, namely pSi-O-C composite, synthesized by electrodeposition harvesting method. This new type of the Si-O-C composite shows impressive results, such as outstanding cyclability with a good discharge capacity of 616 mAh g−1 which reached 10,000 cycles, and a remarkable coulombic efficiency of 99% at the 10,000th cycle. Furthermore, the pSi-O-C composite demonstrates the highest amounts of loaded silicon compared to different types of Si-O-C composite deposited on a Cu and CNTs/Cu substrate.