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If a hypothetical elementary particle called an axion exists, to solve the strong CP problem, a 57Fe nucleus in the solar core could emit a 14.4-keV monochromatic axion through the M1 transition. If such axions are once more transformed into photons by a 57Fe absorber, a transition edge sensor (TES) X-ray microcalorimeter should be able to detect them efficiently. We have designed and fabricated a dedicated 64-pixel TES array with iron absorbers for the solar axion search. In order to decrease the effect of iron magnetization on spectroscopic performance, the iron absorber is placed next to the TES while maintaining a certain distance. A gold thermal transfer strap connects them. We have accomplished the electroplating of gold straps with high thermal conductivity. The residual resistivity ratio (RRR) was over 23, more than eight times higher than a previous evaporated strap. In addition, we successfully electroplated pure-iron films of more than a few micrometers in thickness for absorbers and a fabricated 64-pixel TES calorimeter structure., 5 pages, 5 figures, published in IEEE Transactions on Applied Superconductivity on 8 March 2023

This work demonstrated the first-ever cold-start operation of an ammonia (NH3)-fueled four-cylinder spark ignition engine with an on-board fuel reformer, applying autothermal reforming. In this system, an electrically heated NH3-air mixture was provided to a reforming catalyst and approximately 3 s was found to elapse between the start of engine rotation and the onset of combustion. Stable fast idle operation in conjunction with a cold start was realized with a H2-to-NH3 molar ratio of 2:1. Nearly zero NH3 emissions were achieved during cold start and fast idle until the engine warmed up, by adsorbing unburned NH3 passing through a three-way catalyst before the catalyst was sufficiently warmed up. The NH3 adsorption capacity of this system could be regenerated during the engine warm-up when the engine was running under lean conditions.

In this work, a novel electroless deposition process on the anion exchange membrane (AEM) is proposed. AEM surface has a positively charged functional group, which in general does not allow the catalyst particle, such as Pd, to be formed on the surface. Hence, a different strategy from the conventional catalyzation process was required. We found that the sensitization process using Sn-containing solution, which is widely applied in the electroless plating on nonconductive substrates, hindered the Pd particle modification, which hence inhibited the following deposition reaction. Our several experiments and density functional theory analyses suggest that for Pd particle modification, anion in the bath turned out to play a key role. In particular, Cl− provides the sufficiently strong connection between the precursor Pd2+ and positive functional group of the substrate. This leads to favorable deposition of Pd catalyst particles and metal layer formation on the AEM. Therefore, we conclude that just a single pre-treatment to immerse the AEM films into PdCl2/HCl solution is capable to perform electroless plating on it. We applied the novel process to the electrode formation, such as Pt and Ni–P, on the AEM for hydrogen evolution reaction (HER) as a case study. Both Pt and Ni–P was successfully formed on the AEM. The electrochemical measurements show that those electrodes are able to serve as the catalytic electrode for HER. The electroless process proposed here opens possibility of the direct metal fabrication on ion exchange membrane surface.

In this research, bismuth and tellurium based thermoelectric materials are studied and electrodeposition method was adapted to fabricate the devices. To improve the thermoelectric performance, the thickness of the patterned films was attempted to be increased up to 30 µm. Film properties, such as morphology, composition, resistivity and thermoelectric output, of p-type Cu-added Bi-Sb-Te films were investigated. It was found that the thermoelectric properties were improved with an increase in the film thickness. An annealed buffer layer was created as substrate to control the morphology of Bi-Sb-Te films to be more compact and denser. Finally, 30 µm thick p-type Bi-Sb-Te patterned-films were successfully fabricated, indicating the applicability to micro-thermoelectric devices.

For carbon-neutral transition, technologies are required which enable the efficient conversion of CO2 into valuable feedstocks for chemicals and fuels (e.g., CO, methane, and ethylene). Electrochemical reduction of CO2 (CO2ER) is one of the most promising pathways due to its high product selectivity as well as high activity at mild temperature and pressure, powered by electricity from renewable sources. Among the CO2 reduction products with high selectivity through CO2ER, CO is a useful feedstock to produce methane, methanol, and olefins through conventional catalytic reactions. It is reported that noble metal CO2ER catalysts such as Au and Ag exhibit high CO selectivity[1]. Toward social implementation of CO2ER technology on a commercial scale, earth-abundant elements are more favorable as a catalyst. In recent years, nitrogen (N)-doped carbon materials have attracted much attention for their high CO selectivity comparable to Au and Ag. Previous studies indicate the N-doped carbon catalysts with high content of pyridinic N show high CO generation activity[2]. However, the specific role of pyridinic N (how N contributes to the activity during CO2ER) is still unclear. To establish a design strategy for the efficient N-doped carbon catalyst, the catalytic mechanism involving the pyridinic N must be clarified. In this study, carbon nanotube (CNT) is selected as a model carbon material whose commercial-scale production methods are relatively advanced among carbon materials. With electrochemical and spectroscopic measurements, the local pH dependence of the CO2ER catalytic performance of N-doped CNT (NCNT) was investigated, and the role of the pyridinic N on the CO2ER activity was discussed. The NCNT was prepared by pyrolysis of 1,10-phenanthroline on a multi-walled carbon nanotube as previously reported[2]. CO generation activity was examined in two types of electrochemical systems; the liquid phase electrolysis using an H-cell with a three-electrode system including 4 cm2 NCNT-loaded glassy carbon as a working electrode, and the gas phase using a polymer electrolyte fuel-cell type reactor including membrane-electrode assembly (MEA) with 5 cm2 active area. In the liquid phase electrolysis with CO2 gas bubbling, NCNT showed high faradaic efficiencies toward CO in 1.0 M KHCO3 electrolyte (pH 7.37), while no CO was detected in 1.0 M KHSO4 (pH 0.55) at any applied potentials. In the case of the gas phase reaction, NCNT loaded on a carbon paper (a gas diffusion electrode) with a Nafion® ionomer (Nafion® DE2020CS, The Chemours Company, Delaware, U.S.) showed poor CO selectivity at any cell voltage in both cases using a proton and an anion exchange membrane, while the ionomer substitution to Sustainion® XA-9 (Dioxide Materials, Inc., Florida, U.S.), an anion exchange type, increased the faradaic efficiency toward CO remarkably. From those results, it was confirmed that the local pH near the catalyst surface affects the CO generation activity of NCNT. The local pH dependence on the CO generation activity could be attributed to the CO2 concentration in the electrolyte as well as the protonation of the pyridinic N of the catalyst as previously reported in the system of O2 electroreduction[3]. To observe changes in the local pH and the chemical state of pyridinic N directly, spectroscopic analyses were conducted. We applied our previously reported in situ surface-enhanced Raman spectroscopy measurement system[4] to this reaction to detect the local pH near NCNT surface in the liquid phase as well as the adsorbate species. Surface X-ray photoelectron spectroscopy was also performed to study the changes in the chemical state of N. Those spectroscopic analyses suggested that the factor which affects the CO2ER activity is not only the difference in dissolved CO2 concentration induced from the less acidic condition but also the change in the pyridinic N state. References [1] P. De Luna, C. Haun, D. Higgins, S. A. Jaffer, T. F. Jaramillo, E. H. Sargent, Science 364, eaav3506 (2019). [2] C. Ma, P. Hou, X. Wang, Z. Wang, W. Li, P. Kang, Appl. Catal. B Environ. 250 347-354 (2019). [3] K. Takeyasu, M. Furukawa, Y. Shimoyama, S. K. Singh, J. Nakamura, Angew. Chem. Int. Ed. 60, 5121 (2021). [4] K. Ide, M. Kunimoto, S. Yoshida, M. Yanagisawa, T. Homma, Electroanalysis (in press). Fig. 1. Schematic illustration of experimental setup for in situ SERS measurement of the liquid phase CO2ER with a three-electrode system. Figure 1

Hydrogen peroxide (H2O2), a strong oxidizer, is frequently used for chemical sterilization in aseptic food processing. Due to their inherent robustness, bacterial spores, i.e. spores of Bacillus atrophaeus, are commonly employed to evaluate the efficacy of the sterilization procedure [1]. Despite its widespread use, however, the details of the sporicidal action of H2O2 are not yet fully understood, with various mechanisms being discussed in the literature [2,3]. Here, we employ optical trapping Raman microscopy to elucidate the sporicidal mechanism of H2O2. Optical trapping Raman microscopy allows us to isolate, investigate, and manipulate individual spores from a sample (Fig. 1A). Combining optical microscopy with the real-time, label-free chemical information obtained from Raman spectroscopy directly reveals the sequence of steps that lead to oxidative spore death after H2O2 exposure (Fig. 1B). We find that spore degradation begins with the fast, cooperative release of dipicolinic acid (DPA), a key spore biomarker and a major component of spore’s core. This indicates a breach of the inner membrane surrounding the core. The onset of DPA release depends on the concentration of H2O2. DPA outflux is accompanied by the formation of oxidation products (mostly carbonyl compounds) and oxidation continues after exchange of DPA with the surrounding medium is complete. The remaining spore shell then slowly disintegrates and continues to shrink on a timescale of hundreds of seconds. Simultaneous observation of spore morphology and size by optical microscopy and particle tracking corroborates this three-step mechanism. The presented assay allows on-line monitoring of spore composition and morphology, which directly reveals the mechanism underlying the sporicidal action of H2O2. In addition, trapped spores can be exposed to different chemical or physical stimuli (temperature, light, chemical composition of the surrounding medium, etc.) to investigate a variety of industrially relevant sterilization conditions. Jildeh, Z. B., Wagner, P. H. & Schöning, M. J. Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020. physica status solidi (a) 218, 2000732 (2021). Setlow, P. & Christie, G. What’s new and notable in bacterial spore killing. World J Microbiol Biotechnol 37, 144 (2021). Setlow, P. Spores of Bacillus subtilis: their resistance to and killing by radiation, heat and chemicals. J Appl Microbiol 101, 514-525 (2006). Figure 1

Several issues in developing transition edge sensor (TES) microcalorimeters for the search of monochromatic solar axions expected at 14.4 keV are studied. The potential problem of developing TES’s of this purpose is in that an axion absorber of $$^{57}$$Fe must be placed in close vicinity of a TES. We estimated the minimum distance to avoid magnetic interference from iron using magnetic FEM simulations, and found it 30 $$\upmu $$m for an iron of 5 $$\upmu $$m thickness. We fabricated a TES with a 10 $$\upmu $$m thick iron membrane separated by 60 $$\upmu $$m. We confirmed the superconducting transition for this TES. However, both the residual normal resistance and the transition temperature was different from those of TES without iron. We also estimated the low-temperature thermal conductivity of an iron membrane by measuring the low-temperature electrical resistance and by applying the Wiedemann–Franz law. We estimated the pulse-shape dependency on the interaction position within the $$^{57}$$Fe converted using thermal FEM simulations. We found that the pulse-shape variations will limit the energy resolution to about 30 eV FWHM.

To determine the origin of the difference between reducing agents’ reactivity for electroless deposition processes from the viewpoint of the molecular-level interaction at the solid-liquid interface, the mechanisms for the oxidation of formaldehyde and hypophosphite on Cu and Ni were analyzed and systematically compared by first principles density functional theory (DFT) calculations. The calculated energy diagrams for formaldehyde on Cu(111) showed that the pathway via intermediate CH2O22− was the most favorable. In this case, it was clear that water molecules had an effect. Here, water worked as a reaction mediator to remove the H atom from the OH group of formaldehyde, which resulted in the formation of the stable intermediate, CH2O22−. In contrast, in the case of hypophosphite, the oxidation on Cu(111) could not proceed, because there was no mediation effect from water on the hypophosphite reaction. On Ni(111), however, the oxidation of hypophosphite proceeded favorably, because the Ni surface could well stabilize the intermediate of the reaction due to its d-electron energy states. These results suggest that the mediation effect from the solvent and d-electrons of the metal surface are the key factors in determining the reaction mechanisms and reactivity of reducing agents on metal surfaces.

Discharge behavior of the Zn negative electrode was investigated to elucidate the effects of Li+ as an additive in Zn batteries. Li+ influenced the dissolution of Zn as well as the formation of ZnO (passivation). The dissolution reaction was enhanced by Li+; step-flow dissolution at the Zn surface changed to dissolution from the entire surface. SEM observations of the ZnO formed due to the supersaturation of zincate ions showed morphological changes from acicular crystals to particulate clusters upon introduction of Li+; also, ZnO peaks in XRD patterns decreased. These changes indicated that Li+ suppressed the growth of ZnO, which was caused by the adsorption or incorporation of Li+ into the ZnO crystallites. In situ Raman analysis was carried out to monitor such a difference in the nucleation and growth processes. An E2 mode corresponding to crystalline wurtzite ZnO was dominant in the solution without Li+, while this mode diminished and an E1 (LO) mode corresponding to excess Zn in the interstitial sites of ZnO became strong in the presence of Li+. It was suggested that the Zn excess was introduced due to dominance of nucleation (reactions between zincate species) over the growth process (zincate decomposition at the surface).

The hydrogen evolution reaction (HER) was investigated using Ni catalytic electrodes with micro-patterned surfaces. The present aim was to correlate HER efficiency with the surface wettability of Ni cathodes produced with different micropatterns. Regular Ni microdot arrays, 5–10 μm in diameter, 5–10 μm in pitch were fabricated on a 7 mm diameter Cu substrate and tested in alkaline water electrolysis (AWE) experiments. Using electrodes of this design, it may be possible to relate the electrochemical reaction kinetics to the electrolyte wettability localized to the microdot surface area. The surface microstructures of the electrode considerably influenced the reaction efficiency of the HER during alkaline water electrolysis at −20 mA cm−2. Furthermore, in situ video observations of the electrode surface during the HER revealed that the bubble size increased when the surface wettability of the electrodes was decreased. That is, the surface texture (micro-patterns) affected the HER efficiency by influencing bubble evolution and aggregation behavior. This observation may aid in the design of highly efficient HER catalytic electrodes. Keywords: Hydrogen evolution reaction (HER), Micro-patterned electrode, Surface wettability, Alkaline water electrolysis

Fe-Ni-Pt thin films with compositions within the L10 ordered phase field were prepared by electrodeposition and thermal annealing. The control of the film composition has been demonstrated in terms of its variation under different electrochemical conditions. It was found that while the underpotential co-deposition (UPCD) of Pt with either Fe or Ni is in effect during the deposition process, the anomalous co-deposition between Fe and Ni is not. Isothermal annealing experiments were conducted to investigate the kinetics of the formation of the L10 phase. The control of the film composition allows us to clarify the effects of replacing one element by another, particularly upon the ordering kinetics, the crystal structure, the phase separation behavior, and the magnetic properties. Temperature-dependent magnetic properties of the system were characterized to demonstrate the suitability of Fe-Ni-Pt for heat-assisted magnetic recording (HAMR).

Zn negative electrodes are expected to be used in next-generation batteries. However, irregular shape evolution, such as mossy structures, limits its practical applications. Cationic additive species are useful in suppressing this, and Li+ is a promising species. To identify the effect of Li+ on the nucleation and growth of Zn, this study analyzed the Zn aggregation behavior during electrodeposition with Li+ at the initial stage via experimental methods and theoretical calculations using density functional theory and kinetic Monte Carlo simulations. The results suggest that Li+ affected the surface diffusion of Zn adatoms, changing the nucleation and growth during the initial stage of deposition. Li+ allows Zn adatoms to diffuse rapidly owing to the mitigation of the solvation effect on surface diffusion by forming rigid solvation of Li+ in the vicinity of the surface. This results in two-dimensional nucleation of the Zn(0001) facet, which is supported by the X-ray diffraction measurements. Li+ mitigates protrusion as the initial structure of the mossy structure. This analysis provides valuable insight into the control of the behavior of Zn adatoms and their nucleation and growth.

Zn is one of the promising candidates as negative electrode materials for next-generation secondary batteries, especially those for large capacity applications such as grid-scale energy storage. While the Zn has numbers of attracting features such as crustal abundance, applicability of aqueous system, etc., which enable to realize the secondary batteries with high performance and safety with lower cost, the major drawback is evolution of irregular morphology called mossy structure with highly filamentous features at the electrode surface during charge-discharge cycles. Unlike the conventional dendritic growth which proceeds under diffusion-limited conditions, formation of the mossy structure takes place without such a condition. At the same time, it has been reported that the growth of these irregular structures could be suppressed by applying metallic species as additives to form uniform electrodeposition [1]. We have investigated formation process of the mossy structure on the Zn anode surface, focusing on its initial stage in combination with the additive effects such as Pb and Sn [2]. In this presentation, we will introduce the results of our research on the nucleation and growth process of the mossy structure through experimental analysis and computational modeling. For the theoretical calculation, we attempted to develop multi-scale simulation model by employing density functional theory (DFT) and kinetic Monte Carlo (KMC) approaches [3], and the results will be described focusing on the effects of the metallic additives. This work is financially supported in part by MEXT/JSPS Grant-in-Aid for Scientific Research No. 21H01642. [1] For example, F. Mansfeld, S. Gilman, J. Electrochem. Soc. 117, 1328 (1970); Y. Ito, M. Nyce, R. Plivelich, M. Klein, D. Steingart, S. Banerjee, J. Power Sources, 196, 2340 (2011). [2] For example, T. Otani, M. Nagata, Y. Fukunaka, T. Homma, Electrochim. Acta, 206, 366 (2016); T. Otani, Y. Fukunaka, T. Homma, Electrochim. Acta, 242, 364 (2017). [3] Y. Onabuta, M. Kunimoto, S. Wang, Y. Fukunaka, H. Nakai, T. Homma, J. Phys. Chem.C, submitted.

Lithium with an atomic number of 3 has a small electrochemical equivalent of 6.9 g per Faraday, and a standard electrode potential of -3.045 V, the lowest among metals. For this reason, batteries using lithium as the anode are lightweight and have a high operating voltage. Li/MnO2 batteries and Li/(CF) n batteries have been commercialized using lithium anode, but they are all primary batteries. Lithium metal anodes are prone to generate dendrite during charging. The key to their practical use as anodes for secondary batteries is whether or not dendrite formation can be suppressed. The success technique of dendrite suppression will be indispensable for not only the realization of liquid electrolyte type battery with high energy density such as Li-S batteries and Li-air batteries but also all solid-state lithium metal battery. Thus, it is urgently required to interdisciplinary accumulate our profound understanding of the lithium metal nucleation and growth phenomena. Since Li metal is conventionally electrodeposited in organic electrolytes because of electrochemical window restriction, Li deposition essentially accompanies the adsorption or decomposition of the organic species on the substrate and deposited Li metal. In galvanostatic or constant current electrolysis, the electrolyte decomposes prior to Li deposition and so-called SEI is formed. Therefore, the nucleation and growth of Li is naturally affected by the existence of SEI layer. Characteristics of SEI strongly influences the charge and/or mass transfer kinetics, which affects the nucleation and growth process followed by the morphological variations. Recent work revealed that Li deposition proceeded underneath SEI(1). Also, TEM observations indicated SEI microstructure(2) and the competitive deposition on tip and root of Li dendrite(3). In this study, constant current electrodeposition of Li was carried out in common organic electrolyte instead of ionic liquid(4) to focus on the effect of current density in the initial stage of the electrodeposition. The electrolyte composed of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and PC. A typical three electrode cell was used in Ar glove box (dew point < -90 ℃), varying current density, salt concentration and temperature. The working electrode was Ni wire 500 μm in diameter (Nilaco Corp.). It was coated with FEP fluoroplastic tube as a sleeve so that the portion in contact with the electrolyte was 10 mm in depth. A lithium foil (200 μm in thickness, Honjo Metal Co., Ltd.) was used as the counter electrode and the reference electrode. The cell was mounted in the temperature-controlled aluminum block. The working electrode was immersed in dimethyl carbonate to rinse the surface and dried in vacuum after electrochemical measurements, followed by XPS and UPS analysis, and SEM observation of deposits. Fig. 1 shows the potential behavior for 0 – 10 mC cm-2 immediately after starting at 0.04 - 60 mA cm-2. In all the current densities, the potential did not immediately jump into the equilibrium potential of Li. The coulomb quantity passing before Li precipitation decreases from 8 to 4 mC cm-2 as the current density increases under the lower current densities of 0.04 - 4 mA cm-2. On the other hand, under the higher current densities of 4 - 60 mA cm-2, it is about 4 mC cm-2 which does not change much with the current density. It is deduced that the SEI formed prior to Li precipitation under constant current conditions shows differences depending on the current density and there may be a transition point around 4 mA cm-2. The typical SEM images of the electrode surface after the electrolysis of 100 mC cm-2 at 0.2 and 8 mA cm-2 are demonstrated in Fig. 2. The appearance is quite different between lower and higher current densities. At 0.2 mA cm-2, both whiskers with several micrometers in length and granular precipitates of 300 - 400 nm in size can be seen. On the other hand, at 8 mA cm-2, no granular shapes are noticed and substantially only whiskers of around 500 nm in length are homogeneously distributed. Li nucleation and growth behaviors will be further examined to focus the effect of not only current density but also salt concentration and temperature. Nucleation & growth behavior of Li electrodeposited in PC electrolyte may be compared with conventional metal electrodeposition researches in aqueous solution system in order to find out any similarity or dissimilarity between both systems. References Jana, R. E. García, Nano Energy, 41, 552–565 (2017). Li, Y. Cui et al., Joule, 2, 2167−2177 (2018). Li, Y. Yu et al., Science, 358, 506–510 (2017). Nishida, K. Nishikawa, M. Rosso and Y. Fukunaka, Electrochim. Acta, 100, 333-341 (2013). Figure 1

This study aimed to examine correlates of lifetime and past-year HIV testing among men who have sex with men (MSM) in Japan. A unique, anonymous online self-report survey was conducted in 2015. A total of 776 participants completed the survey and answered questions on sociodemographic information, HIV-testing experience, history of syphilis, experience talking about HIV, recognition of AIDS-related community-based organization (CBO) materials, and sex behaviors. HIV-testing experience and related factors were assessed for two groups: regional cities and Tokyo and Osaka. A Poisson regression analysis revealed that higher lifetime HIV testing was associated with older age, previous syphilis diagnosis, and experience talking about HIV. Moreover, higher HIV testing in the past year was associated with experience talking about HIV with friends and recognition of HIV-related CBO materials. Increased dissemination of HIV-related information provided by CBOs may, therefore, be an effective prevention policy intervention targeted at Japanese MSM to promote regular testing and maintain their interest in HIV issues.

The controlled design of biosensors based on the photo-electrochemical technique with high selectivity, sensitivity, and rapid response for monitoring of mono-bioactive molecules, particularly dopamine (DA) levels in neuronal cells is highly necessary for clinical diagnosis. Hierarchical carbon-, nitrogen-doped (CN) nickel oxide spear thistle (ST) flowers associated in single-heads (S), and symmetric and asymmetric-double heads (D and A, respectively) that are tightly connected through a micrometric dipole-like rod or trunk were fabricated by using a simple synthetic protocol. The CN-ST flower heads were decorated with dense nano-tubular like hedgehog needle skins in vertical alignments. These designated architectures are key features for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules. The exceptional electrode designs produced numerous catalytically active sites, large surface area, and high electron-transfer mobility. The active coating of carbon–nitrogen nanospheres significantly enhanced the photo-electrocatalytic activity of the prepared biosensor electrodes and prevented leakage of photocatalytic activity under long-term exposure to irradiation. Among all photo-electrochemical assays, the biosensors showed significant sensitivity and selectivity for DA in the presence of interfering molecules such as ascorbic acid (AA), uric acid (UA), adrenaline (A), and noradrenaline (NA). The photo-electrochemical property of the CN-SST-{110} crystal surface electrode showed significant sensing performance for DA in terms of unimpeded diffusion pathways, a wide concentration-detection range, and a low detection limit, even in the presence of potentially interfering molecules compared with other electrode-modified CN-DST-{111} and CN-AST-{101} crystal surfaces. Furthermore, the CN-SST photo-biosensor electrode shows potential in the selective and sensitive determination of DA in real samples, such as human serum and secreted DA from living cells. This finding indicates that the hierarchical ST biosensor may enable analytical discrimination and monitoring of DA and can be employed for clinical diagnosis application.

We demonstrate an electrochemical deposition process suitable to form arrays of L10 Fe–Pt nanodots with hard magnetic properties via electron-beam lithography, template deposition, and thermal annealing. Synthesis parameters are selected by growing single and multilayer blanket films and investigating the effect of thermal annealing on the various films. We find that the fastest ordering transformation is achieved in eight-layer Fe–Pt multilayers with a sublayer thickness of 2.5 nm, while a single Fe–Pt layer or four- and twenty-layer multilayers exhibit a more sluggish ordering process due to the imperfect layering (twenty-layer) or to the limited mean free path upon annealing (single- and four-layer); the coercivity of the eight-layer Fe–Pt multilayer after annealing at 450 °C reached 6.6 kOe, whereas the single Fe–Pt layer showed only 1.0 kOe. TEM imaging and diffraction show that the L10 Fe–Pt nanodot arrays are single crystal with a (111) orientation, suggesting a facile L10 ordering when using a mul...

In this work, the behavior of an additive designed to aid electrodeposition in through-silicon via (TSV) structures is monitored directly using surface enhanced Raman spectroscopy (SERS). A horizontal via structure with a transparent ceiling (corresponding to the side wall of the TSV) was prepared, which allowed the probe laser to reach the bottom of the structure (corresponding to the opposite side of the TSV wall). Au nanoparticles of size ~5 nm deposited on the bottom of the structure produced a SERS effect and enhanced the Raman signals of chemical species migrating nearby. The diffusion behavior of the additive inside the via structure could be monitored with high sensitivity by detecting these enhanced signals. As a case study, this direct measurement method was successfully used to follow the diffusion of a small amount of Janus Green B, a common additive for Cu electrodeposition. The diffusion coefficient of the additive determined by these measurements turned out to be different to that estimated electrochemically on flat electrodes. One of the advantages of our direct measurement setup is the ability to exclude the undesirable environmental changes that often occur in electrochemical measurements. Keywords: Through-silicon via, Cu electrodeposition, surface enhanced Raman spectroscopy, additives

Heat shock protein 47 kDa (HSP47), an ER-resident and collagen-specific molecular chaperone, recognizes collagenous hydrophobic amino acid sequences (Gly-Pro-Hyp) and assists in secretion of correctly folded collagen. Elevated collagen production is correlated with HSP47 expression in various diseases, including fibrosis and keloid. HSP47 knockdown ameliorates liver fibrosis by inhibiting collagen secretion, and inhibition of the interaction of HSP47 with procollagen also prevents collagen secretion. Therefore, a high-throughput system for screening of drugs capable of inhibiting the interaction between HSP47 and collagen would aid the development of novel therapies for fibrotic diseases. In this study, we established a straightforward method for rapidly and quantitatively measuring the interaction between HSP47 and collagen in solution using fluorescence correlation spectroscopy (FCS). The diffusion rate of HSP47 labeled with Alexa Fluor 488 (HSP47-AF), a green fluorescent dye, decreased upon addition of type I or III collagen, whereas that of dye-labeled protein disulfide isomerase (PDI) or bovine serum albumin (BSA) did not, indicating that specific binding of HSP47 to collagen could be detected using FCS. Using this method, we calculated the dissociation constant of the interaction between HSP47 and collagen. The binding ratio between HSP47-AF and collagen did not change in the presence of sodium chloride, confirming that the interaction was hydrophobic in nature. In addition, we observed dissociation of collagen from HSP47 at low pH and re-association after recovery to neutral pH. These observations indicate that this system is appropriate for detecting the interaction between HSP47 and collagen, and could be applied to high-throughput screening for drugs capable of suppressing and/or curing fibrosis.

FeCuPt nanodot arrays were fabricated by electrodeposition onto a nanopore patterned substrate fabricated by electron beam lithography (EBL), for the purpose to manufacture and characterize model bit-patterned media. Addition of Cu to FePt was carried out to accelerate the phase transformation of FePt into the $L1_{0}$ -ordered phase in order to fabricate nanodot arrays with hard and uniform magnetic properties. Composition of the FeCuPt ternary alloy films was optimized by varying applied potential and CuSO4 concentration to form single $L1_{0}$ phase (40–50 at% Pt and ~25 at% Cu). Annealing at 450 °C resulted in the phase transformation from fcc to $L1_{0}$ in FeCuPt ternary alloy films, whereas FePt binary alloy films did not show a phase transformation. Perpendicular coercivities of FeCuPt and FePt were 6 and 1 kOe, respectively, annealing at 450 °C, indicating the formation of the $L1_{0}$ phase with lower annealing temperature by Cu incorporation. FeCuPt nanodot arrays with 20 nm in diameter and 35 nm in pitch were successfully fabricated with the nanopore patterned substrate fabricated by EBL. In addition, cross-sectional transmission electron microscope analysis of FeCuPt nanodot arrays showed clear stacking of the $L1_{0}$ (111) lattice in a perpendicular direction through the growth direction having a single crystal nature, whereas phase transformation was insufficient with FePt nanodot arrays. The collective results have successfully demonstrated the electrochemical fabrication of ultra-fine FePt nanodot arrays with $L1_{0}$ structure by promoting $L1_{0}$ ordering with Cu additions.

In this work, we developed a precise approach to analyze local proton concentration at the solid/liquid interface of electrodes, i.e. “surface pH”, during electrochemical reactions. For this, surface enhanced Raman spectroscopy (SERS) was applied to analyze pH-dependent structural changes of the –COOH group of p-mercaptobenzoic acid (p-MBA) modified onto Au nanoparticles (NPs) on the substrate close to a working electrode. Measurements using this system identified deprotonation of –COOH of p-MBA. Since preliminary experiments and density functional theory calculations suggest that the pKa of p-MBA attached to Au NPs is close to that in bulk solution, the SERS results indicate pH increase due to proton consumption by the cathodic overpotential of the working electrode. As an example, we applied this system to surface pH monitoring in electrodeposition process of Ni in an acidic bath, which indicated the validity of our method for precise detection of pH changes at electrode interfaces in situ.

The effect of adding Si powder/granules on the electrochemical reduction rate of SiO2 granules in molten CaCl2 was investigated. Various starting materials were prepared by mixing different amounts (up to 80 mass pct) of Si powder/granules (four different sizes

In recent years, photovoltaic power generation using silicon solar cells has been increasing significantly. Currently, the solar-grade silicon (SOG-Si) with 6-7N (99.9999~9%) level of purity, for photovoltaic power generation is manufactured using Siemens process, which consumes drastic amount of energy & time, and uses “silica ore” as raw material that might be possibly depleted soon. There are number of alternative approaches that have been developed for solar-grade silicon such as the metallurgical process, zinc reduction process or hydrogenation process. However, these processes still require substantial energy input for the fusion or gasification and reduction of metallurgical-grade silicon (MG-Si). Therefore, there is a need to develop an alternate production process for SOG-Si that would stabilize the problems including the cost factor. Our research group focuses on the development on new preparation process of SOG-Si from diatomaceous earth as that is one of the promising candidate with abundant raw material of silica reserves: combination of wet chemical process and channel reactor process. The wet chemical process includes dissolution/precipitation treatment of diatomaceous earth with NaOH + TMAH mixture solvent with pH adjustment, followed by acid leaching [1-2]. The dissolution/precipitation treatment preliminarily purifies silica by utilizing difference in pH dependences of solubility of Si and other impurities. In the acid leaching, HCl aqueous solution subsequently removes impurities from gel-state silica. These processes are profitable to remove large amount of impurities, which were however found to be hard to eliminate B that affects significantly the electrical properties of SOG-Si. Series of our studies formerly found the followings: (i) liquid-liquid extraction process using 2,2,4-trimethyl-1,3-pentanediol (TMPD) as an extractant in organic phase (toluene) works very well to extract the B (boric acid in solution) from aqueous solution, (ii) flow type reactors are more suitable and profitable than batch type reactors for practical uses as it provides a long contact period [3-4], and (iii) the liquid-liquid interfacial reaction rate of boric acid and TMPD is sufficiently high to set the process diffusion-limited. Based on these findings, this study focuses on the design and testing of the practical channel rector in a larger scale (135x100x10 mm), which is fabricated using 3D printing technology. The channel was designed to have 2 characteristic structures: a throat structure that shows gradually diverging part after converging (converging/diverging structure) near Y shaped inlets and obstacles structure on downstream, as shown in Fig.1. The silica solution (aqueous phase) was prepared and injected into one of the inlet and TMPD (organic phase) solution into the other inlet. Vortices were generated around diverging part, leading to efficient mixing of each phase to produce smaller droplets of one phase dispersed into the other, which was retained by obstacles part efficiently. This continuous droplet production enhances mass transfer of boric acid to the interface to react with TMPD. 5 times repeating application found to be 99.65% removal of B at the flow rate 350 ml/min. From these results, this kind of converging/diverging structure and presence of obstacles will enhance the mixing efficiency between aqueous and organic phases, which in turn produces maximum extraction efficiency. These kinds of channel reactors are profitable for silica purification at industries. References: [1] M. Bessho, Y. Fukunaka, H. Kusuda and T. Nishiyama: Energy & Fuels, 23, 4160–4165 (2009). [2] T. Homma, N. Matsuo, X. Yang, K. Yasuda, Y. Fukunaka and T. Nohira: Electrochimica Acta 179 (2015) 512–518. [3] N. Matsuo, Y. Matsui, Y. Fukunaka and T. Homma: Journal of The Electrochemical Society, 161 (5) E93-E96 (2014). [4] N. Matsuo, Y. Matsui, Y. Fukunaka, and T. Homma: ECS Transactions, 50 (48) 103-108 (2013). Figure 1

Effects of Pb and Sn additives on electrodeposition of Zn were investigated for the applications in Zn secondary battery, focused on their roles on morphological evolution. Similarly to well-known effect of Pb addition to smoothly electrodeposit Zn film surface, Sn also exhibited to suppress the formation of mossy structures, which were highly filamentous Zn electrodeposits to cause frequently battery failure. Pb significantly shifted deposition potential of Zn to negative value at concentration less than 1.0 mmol dm −3 , while Sn showed no substantial effect even at 50 mmol dm −3 . The morphological evolution analysis demonstrated that the addition of 1.0 mmol dm −3 Pb significantly altered nucleation behavior of Zn at initial stages of deposition; stacking of layer-like structures (microsteps) were altered to discrete and uniform nuclei of Zn preferentially oriented to (002) direction. In contrast, with Sn additive, morphological features at the initial stage of deposition were similar to that without additive. However, microsteps evolution was gradually suppressed and relatively strong (002) texture of electrodeposited Zn was mitigated by Sn addition. These results suggested that the beneficial roles of Pb and Sn addition on Zn morphological evolution were ascribed to different reasons; Pb diminished the active growth sites of Zn surface by suppressing the deposition reaction of Zn, while Sn suppressed microsteps evolution by different texture evolution of Zn.