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We report the synthesis of nitrogen-doped graphene oxide, with 5.7-7.0 wt % nitrogen doping, from different sizes of precursor graphite and study its effect on the oxygen evolution reaction (OER) activity of IrO

BACKGROUND: Podocyte depletion causes glomerulosclerosis, and persistent podocyte loss drives progression to ESKD. Urinary sediment podocin (u-sed Pod) mRNA excretion and urinary supernatant podocalyxin (u-sup PCX) protein have been used to monitor disease activity in glomerular diseases. However, the differences in these markers among pathologies have not been investigated. We examined the roles of these markers in kidney diseases. METHODS: From January 2013 to March 2016, early morning urine samples were collected from 12 healthy controls and 172 patients with kidney disease (n=15 patients with minor glomerular abnormality with mild proteinuria and/or microscopic hematuria, n=15 with minimal change nephrotic syndrome [MCNS], n=15 with membranous nephropathy [MN], n=60 with IgA nephropathy [IgAN], n=19 with crescentic GN [Cres GN], n=10 with lupus nephritis [LN], and n=38 with other kidney diseases). We examined u-sed Pod mRNA excretion, u-sup PCX protein, and the urinary protein-creatinine ratio (u-PCR). RESULTS: u-sed Pod mRNA excretion was significantly correlated with u-sup PCX protein (r=0.37, P

In this study, in situ electrochemical Raman spectroscopy was applied to clarify the charge storage mechanism in three types of anodes, synthetic graphite, reduced graphene oxide (rGO), and nitrogen-doped reduced graphene oxide (N-rGO). The Li+ intercalation phenomenon was measured in LiPF6 electrolyte solution using a modified coin cell setup. The synthetic graphite anode showed the splitting of the G peak at the potential E < 0.2 V vs. Li/Li+, corresponding to the formation of a graphite intercalation compound (GIC) and its second-order 2D peak was found to be red-shifted due to charge transfer and induced strain in the potential region of 0.5 to 0.15 V vs. Li/Li+. In the case of rGO, the lattice defects assisted in large and early intercalation of electrolyte ions, which is confirmed by the red-shift in the G peak (∼36 cm−1) and its early disappearance below 0.3 V vs. Li/Li+, respectively. Unlike rGO, nitrogen vacancies in N-rGO provide active sites for Li+ intercalation, resulting in enhanced charge transfer, displayed by the large red-shift in the G peak (∼55 cm−1) and blue-shift in the D peak. In addition, a new Raman peak at 1850 cm−1 was observed in N-rGO for the first time, corresponding to the formation of a reversible intermediate species from the interaction between Li+ and nitrogen vacancies. This work demonstrates the use of a simple in situ technique to get insight into the nano-carbon electrodes during device operation and to reveal the role of doped nitrogen atoms for Li+ intercalation.

The current research deals with the study of boron and nitrogen co-doped reduced graphene oxide (BN-rGO) as a support material for iridium oxide (IrO2) nanoparticles for oxygen evolution reaction (OER) catalysis. The synthetic approach for the IrO2–BN-rGO catalyst involves the combination of pyrolysis and hydrothermal methods used for hierarchical nanostructures. BN-rGO possesses B–N, B–C, and N–C functional groups to support and stabilize the IrO2 catalyst nanoparticles. The altered electronic states of IrO2 on the BN-rGO support are compared with those of IrO2 on a non-doped support, rGO (IrO2–rGO), and on commercial BN sheets (IrO2–c-BN). The catalyst shows a low overpotential (300 mV at 10 mA cm−2), high current density (55 mA cm−2 at 1.65 V), and significantly high durability (12 350 cycles; 45 h) in an acidic environment. The high stability of IrO2–BN-rGO may result from the presence of a chemically and electrochemically stable B–N bond. We confirm that other functional groups (B–C and N–C) and the rGO framework are equally crucial for better attachment of IrO2 nanoparticles.

Background Chronic hypoxia may play a pivotal role in the development of diabetic nephropathy (DN). However, the precise mechanisms underlying progressive hypoxia-induced glomerular injury remain unclear. Methods We housed db/db mice in a hypoxia chamber (12% O2) for up to 16 weeks beginning at 8 weeks of age. Various urine, serum and kidney abnormalities and glomerular messenger RNA (mRNA) expression were compared with those in age-matched db/db mice housed under normoxia. Results Levels of urinary albumin and podocalyxin (PCX) were significantly higher in hypoxic mice early during hypoxia. Ultracentrifugation of urine samples revealed that podocytes in the hypoxic mice shed PCX-positive microparticles into the urine. After 16 weeks of hypoxia, the mice also had higher hematocrits with lower serum glucose and various degrees of mesangiolytic glomerulosclerosis with microaneurysms and the infrequent occurrence of nodular lesions. Immunohistologically, hypoxic mice showed significantly decreased endothelial cell densities early during hypoxia and decreased podocyte densities later. In both hypoxic and normoxic mice, glomerular macrophage and transforming growth factor-β1 (TGF-β1) staining significantly increased with aging, without changes in vascular endothelial growth factor or endothelial nitric oxide synthase (eNOS). Glomerular mRNA expression of monocyte chemoattractant protein-1, eNOS and TGF-β1 was significantly enhanced in the hypoxic mice. Conclusions These results indicate that chronic hypoxia induces advanced glomerulosclerosis with accelerated albuminuria triggered by mesangiolysis and podocyte injury in a murine model of DN.

For low-level tritium measurements using a liquid scintillation counter, scintillation vial selection is important. The applicability of polyethylene (PE) vials was studied. Three types of vials we...

In inertial confinement fusion (ICF), a fuel target containing deuterium and tritium is used. In recent ICF experiments on the Gekko XII LFEX facility at the Institute of Laser Engineering at Osaka...

Various postoperative predictive markers following cardiovascular surgery have been examined for use in the current aging population. The controlling nutritional status (CONUT) score, which is advocated not only as a screening tool for poor nutritional status, but also as an immunonutritional assessment, has started to attract attention in several clinical settings, such as in cancer and heart failure patients. The aim of this study was to evaluate the value of the CONUT score as a postoperative prognostic marker in patients who underwent cardiovascular surgery. A total of 75 patients who underwent elective cardiovascular surgery between January 2015 and October 2017 were retrospectively analyzed. The patients were divided into two groups according to their preoperative CONUT score (i.e., CONUT

Background Although metabolic syndrome traits are risk factors for chronic kidney disease, few studies have examined their association with urinary biomarkers. Methods Urinary biomarkers, including A-megalin, C-megalin, podocalyxin, albumin, α1-microglobulin, β2-microglobulin, and N-acetyl-β-D-glucosaminidase, were cross-sectionally assessed in 347 individuals (52.7% men) with a urine albumin-to-creatinine ratio (ACR) Results Participants had a mean body mass index, estimated glomerular filtration rate (eGFR), and median ACR of 23.0 kg/m2, 74.8 mL/min/1.73 m2, and 7.5 mg/g, respectively. In age- and sex-adjusted logistic regression analysis, A-megalin and albumin were significantly associated with the clustering number of metabolic syndrome traits (3 or more). After further adjustment with eGFR, higher quartiles of A-megalin and albumin were each independently associated with the clustering number of metabolic syndrome traits (adjusted odds ratio for A-megalin: 1.30 per quartile, 95% CI 1.03–1.64; albumin: 1.42 per quartile, 95% CI 1.12–1.79). Conclusions Both urinary A-megalin and albumin are associated with the clustering number of metabolic syndrome traits. Further research on urinary A-megalin is warranted to examine its role as a potential marker of kidney damage from metabolic risk factors.

Nondestructive measurement of tritium (T) content in solid materials is important for safe and cost-effective disposal of contaminated wastes, and beta-ray induced X-ray spectrometry (BIXS) has bee...

The present work details the development of IrO2 nanoparticles (nps) supported on B-doped reduced graphene oxide as an oxygen evolution reaction (OER) electrocatalyst for electrochemical water splitting. IrO2 on boron-doped reduced graphene oxide (B-rGO) is synthesized via sequential steps of pyrolysis to prepare B-rGO and a hydrothermal method for modification of B-rGO with IrO2 nps. With 2 wt% boron doping in graphene, a 0.10 V decrease in the OER onset potential is observed for IrO2 catalysts on B-rGO (IrO2-B-rGO). The Tafel slope for the OER on B-rGO is estimated to be 124.8 mV dec−1, which is lower than that on IrO2-rGO and suggests strong adsorption of intermediates such as OH on the IrO2 surface by the B-doping of graphene in acidic solution. In this article, we demonstrate the effect of boron doping on the electronic structure modification of the IrO2 nps, which is expected to generate more electrocatalytic centers and enhance the catalytic activity.

Liquid scintillation counters (LSCs) have been widely used for low-level tritium measurements. To obtain an accurate tritium activity using a LSC, a quenching correction is required. The quenching ...

The magnetic properties of Pd–Co alloys and their hydrides were investigated. From the temperature dependences of magnetization of Pd–Co alloys, simple ferromagnetic behaviors were observed, and the Curie temperatures are estimated to be 220, 315, and 350 K for Pd0.96Co0.04, Pd0.92Co0.08, and Pd0.90Co0.10, respectively. The Pd–Co alloys were hydrogenated under 100 kPa hydrogen gas pressure. After hydrogenation, the temperature variations of magnetization revealed two magnetic transitions implying that there are two phases in the hydrogenated Pd–Co: the hydrogen dissolution and hydride phases. The hydrogen contents ([H]/[Pd–Co]) and the Curie temperature (TC) of the hydride phase are deduced that [H]/[Pd–Co] = 0.53, 0.43 and 0.36 with TC = ≤50, 100 and 120 K for Pd0.96Co0.04, Pd0.92Co0.08, and Pd0.90Co0.10 hydrides, respectively. The magnetization against externally applied field measured at 50 and 300 K indicated that the magnetic moments per a single ion (Pd, Co) of the hydrides are always smaller than those of the original Pd–Co alloys. First principle calculations for the magnetic moments provided quite consistent results with the experimental ones.

Four different Geant4 physics packages, Livermore, Penelope, Emstandard Opt4 and Emstandard Opt1, have been benchmarked against real data in the low-energy region ≤18.6 keV, with regard to β-decay induced X-ray spectrometry (BIXS) applications. The tritium data of two different BIXS experiments have been compared against the calculated detection efficiencies and spectral shapes. All four physics package results showed the main features of the experimentally obtained spectra. The spectral shape was reproduced best by the Penelope physics package. Regarding the detection efficiency, the current data set showed the best agreement with Emstandard Opt1 output, while the maximum deviation of ≤24% was given by the Emstandard Opt4 result.

Fig.1 Cycle performance and Coulomb efficiency of graphite/CNT/CNF composite electrodes Introduction Currently, lithium-ion batteries (LIBs) have been the primary power source for electric vehicles and portable devices. LIBs consist of anodes (e.g. graphite), cathodes (e.g. LiCoO2: LCO), and electrolytes,[1] and are dis-/ charged as Li+ de-/ intercalate between the electrodes. Since LIBs require expensive fluorinated polymer as binders (e.g. poly (vinylidene fluoride): PVDF) and a volatile and toxic organic solvent such as N-methyl pyrrolidone (NMP), cheaper and easier-to-handle materials are necessary. Furthermore, the metal substrates (Cu, Al foil, etc.) as the current collectors are heavy and reduce the weight energy density of electrodes. Therefore, providing alternatives to the conventional components of LIB electrodes is a key challenge. Developing functional nanocomposites using sustainable natural resources is one of the most importance strategies.[2] Conductive thin films of cellulose nanofibers (CNFs) combined with carbon nanotubes (CNTs) have been reported as novel carbon composites.[3] Environmentally friendly and only carbonaceous electrodes without PVDF and organic solvents, and graphite are normally used for anodes. As an allotrope of graphite, CNTs have been approved to be a suitable anode material due to their unique structure (one-dimensional cylindrical tubule of graphite sheet), high conductivity (106 Sm-1 at 300 K), low density, high rigidity (Young’s modulus 1 TPa), and high tensile strength (up to 60 GPa).[4] In this study, the free-standing carbon composite anodes were successfully fabricated by using ultrasonication of CNF/ CNT or graphite mixture and vacuum filtering. Graphite slurry as the active material layer was dispersed in DI-water as the solvent containing CNF binder. This composite film has a dual-layer structure consisting of graphite/CNF active materials layer and CNT/CNF layer; here, the CNT/CNF layer with a thickness of about 10 μm is utilized as a current collector replacing the conventional metal substrate. These fabricated electrodes were evaluated by structural evaluation and dis-/ charge measurements. Experimental method CNF gel (2 wt%, Rheocrysta, DKS Co. Ltd.) and functionalized (carboxylic acid) multi-walled CNT (f-MWCNT, Sigma-Aldrich) were suspended in DI-water and sonicated for 2 h. Synthetic graphite was dispersed in DI-water with 5 wt% CNF and 10 wt% Carbon Black (CB) as a conductive material and sonicated for 30 min. Nanocomposite dual-layer films were formed by vacuum-filtering the dispersion using PVDF (pore size: 0.1 μm) membrane filters. These films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), and Raman spectroscopy. The conductivity was measured by four probe method. The electrochemical properties of the free-standing electrode were measured using coin cells at room temperature. The coin cells were assembled in an argon-filled glovebox using Li as a counter electrode, glass fiber filter as a separator, and 1 M LiPF6 in a 1:1 (volume) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as the electrolyte. Charge-discharge characteristics were recorded from 0.01 to 3 V at charging speeds of 0.1 – 2 C. The electrochemical impedance spectra (EIS) were measured in the frequency range from 100 mHz to 100 kHz with a potential perturbation at 5 mV. Results CNF combined with CNT constructs a robust conductive fibrous network, and CNT linked with graphite builds electronic conductive paths to improve the electronic conductivity. Specific capacities of the electrode were 44 mAhg-1 at 2 C and 272 mAhg-1 at 0.5 C, respectively (Fig.1). The discharge capacity of the first cycle was 363 mAhg-1 at 0.1 C. After 125 cycles, the discharge capacity was 255 mAhg-1 at 0.5 C. The ratio of the charge and discharge capacities (Coulombic efficiency) suggests that the charge-discharge behavior is stable in the cycle measurement, indicating that the irreversible capacity was small. Other information obtained by cyclic voltammetry (CV), and EIS measurement and further results will be shown in the presentation. In summary, we successfully fabricated the graphite/CNT/CNF composite film as environmentally friendly and lightweight anodes for the first time. The present results indicate that graphite/CNT/CNF composite film is a good candidate of flexible free-standing anodes. This research focused on CNFs as a promising alternative to conventional battery materials, and CNFs were successfully used to fabricate electrodes without using expensive PVDF binders and toxic organic solvents. Moreover, the gravimetric energy density was improved by replacing the conventional heavy Cu foil with a lightweight and thin composite film of CNT/CNF. References [1] M. Weiss, et al., Adv. Energy Mater. 2021, 11, 2101126. [2] C. Chen, et al., Comp. Sci. and Technol. 2018, 156, 103-108. [3] S. Cao, et al., ACS Appl. Mater. Interfaces 2015, 7, 10695-10701. [4] C. de las Casas, et al., J. Power Sources 2012, 208, 74-85. Figure 1

Tritium (T) distribution on the plasma-facing surfaces (PFSs) and inside castellation of Be limiter tiles from the JET tokamak with the ITER-like wall (ILW) was analyzed using imaging plate (IP) technique and β-ray induced X-ray spectrometry (BIXS). Regarding to PFSs, the outer poloidal limiter (OPL) showed significantly higher T concentrations than the inner wall guard limiter (IWGL) and upper dump plate (DP). The concentration of T on OPL was high at the central part. However, deuterium (D) and metallic impurities showed maximum concentration at the edges. This difference in distributions indicated different deposition and retention mechanisms between T and D. In contrast, deposition profiles of T concentrations on the castellated surfaces extended up to ∼ 5 mm into the gap, i.e. were similar to those of D and metallic impurities found by ion beam analysis.

BACKGROUND: The development of glomerulosclerosis in FSGS is associated with a reduction in podocyte number in the glomerular capillary tufts. Although it has been reported that the number of urinary podocytes in FSGS exceeds that of minimal-change nephrotic syndrome, the nature of events that promote podocyte detachment in FSGS remains elusive. METHODS: In this study, we provide detailed, morphologic analysis of the urinary podocytes found in FSGS by examining the size of the urinary podocytes from patients with FSGS, minimal-change nephrotic syndrome, and GN. In addition, in urinary podocytes from patients with FSGS and minimal-change nephrotic syndrome, we analyzed podocyte hypertrophy and mitotic catastrophe using immunostaining of p21 and phospho-ribosomal protein S6. RESULTS: The size of the urinary podocytes was strikingly larger in samples obtained from patients with FSGS compared with those with minimal-change nephrotic syndrome and GN (P=0.008). Urinary podocytes from patients with FSGS had a higher frequency of positive immunostaining for p21 (P

Graphene and heteroatom-doped graphene are potential candidates for high-performance energy storage applications, such as supercapacitors. Herein, we have studied the structure and defect generation in nitrogen-doped reduced graphene oxide (N-rGO), synthesized via pyrolysis of urea in a wide temperature range (600–900 °C). Nitrogen-doped defect densities were analyzed in detail by the deconvolution of the Raman spectrum, where we found the importance of additional I and D’’ peaks. I peak is found to be sensitive to the dopant, and D” peak is consistent with the crystallinity, which are further revealed by X-ray photoelectron spectroscopy and X-ray diffraction measurements. Synthesized N-rGO was then investigated for the supercapacitor electrode. N-rGO synthesized at 800 °C, having low crystallinity (crystallite size 3.44 nm), highest degree of reduction (C/O ratio = 23), high specific surface area (152.3 m2 g−1), and presence of both pseudocapacitive and electric double layer behavior, resulting in highest areal capacitance of 138.4 mF cm−2, lowest self-discharge rate, and exceptional capacity retention of 121.7% after 10,000 cycles of charge–discharge. The synthesized electrode material has also been tested for a symmetric supercapacitor cell showing high specific capacitance 66.8 F g−1 in 0.5 M H2SO4 electrolyte. This study is a first of its kind of structural evaluation and Raman characterization of N-rGO for application in supercapacitor cell.

In this paper, we report synthesis of novel nanoparticle catalyst of iridium oxide supported on carbon nanotube (IrO2/CNT) and characterization of activity and durability for oxygen evolution reaction (OER). The IrO2/CNT catalyst was prepared from iridium complex and COOH-CNT by hydrothermal method. The synthesized IrO2/CNT catalysts was characterized by transmission electron microscopy, x-ray diffraction, Raman microscopy, Fourier transfer-infrared spectroscopy, x-ray photoelectron spectroscopy, thermogravimetric analysis and electrochemical methods. The average particle size of the IrO2 particles on CNT is 1.7 nm and the loading amount of IrO2 is 4 wt%. The XPS measurement reveals that Ir complex was completely converted to iridium oxide through hydrothermal treatment. The IrO2/CNT catalyst showed sufficient performance for OER activity and durability in sulfuric acid solution. Our results indicate that IrO2/CNT is one of the prospective candidate catalysts for water electrolyzer.

The 125I pulse-height spectra via a liquid scintillation counter (LSC) displayed notable variations. The counting efficiencies of higher and lower energy peaks increased and decreased, respectively, with the enhancement of the amount of high atomic numbered elements within the cocktails. This tendency was ascribed to the increasing probability of the interaction of photons with the scintillation cocktail. Moreover, it was noted that the shape of a 125I spectrum strongly depends on the amount of high atomic numbered elements.

Tritium beta-ray induced X-ray spectra in various gas mediums were simulated by Monte Carlo simulation using Geant4 tool kit. The simulated beta-ray induced X-ray spectrum (s-BIX spectrum) was composed of the bremsstrahlung component and characteristics X-rays from constituent elements. The total number of photons in s-BIX spectrum decreased with increasing pressure of medium except argon. In argon medium, the characteristics X-ray of argon was generated by beta particles from tritium decay, and the contribution of Ar-Kα and -Kβ compensated the reduction of bremsstrahlung generated by solid matter with increasing argon pressure. At 0.001 atm of medium pressure, the total counts in s-BIX spectrum was independent from gas medium. Therefore, the gas medium dependence in BIXS at low pressure (less than 0.001 atm) was not serious issue.

Recently, progress toward sustainable societies with renewable energies is a critical issue to overcome environmental and social problems, for example, global warming and depletion of fossil fuels. To utilize effectively renewable energies such as solar and wind energy, conversion of renewable energies to hydrogen via water electrolysis is one of the most attractive approaches for energy storage. However, for the practical application of water electrolysis systems, its activity, durability, and catalysts cost are insufficient due to high over-potential and low kinetics of electrode reactions, especially, oxygen evolution reaction (OER) at the anode [1,2] for polymer electrolyte water electrolyzer (PEWE). As anode catalysts, iridium oxide (IrO2) particles have been used because of its high activity and durability for OER. However, iridium is one of the platinum group metals and reducing loading amount of iridium is required to reduce catalyst cost. Recently, we have successfully synthesized novel catalysts, IrO2 nanoparticle catalysts supported on nanocarbon materials with improved specific surface area, surface area per weight, of anode catalysts for PEWE. In this study, we focus on modification of IrO2 catalysts by doping of hetero atom (N) on supporting materials and characterization its electronic state condition and catalytic activity for OER. Novel catalyst of IrO2 nanoparticles supported on nitrogen-doped reduced graphene oxide (N-rGO) was prepared by hydrothermal synthesis. Graphene oxide (GO) prepared by modified Hummers method [3] was mixed with urea and hydrothermally treated at 180 ˚C for 12 h to synthesize N-rGO. For the synthesis of IrO2 / N-rGO catalysts, mixture of H2IrCl6 complex and N-rGO dispersed in ethanol/water mixture solution was stirred at 80 ˚C for 6 h in a flask to attach iridium oxide colloid to N-rGO and heated at 150 ˚C for 4 h in a hydrothermal autoclave to form IrO2 nanoparticles. The IrO2 / N-rGO catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersed X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The OER activity of the IrO2/ N-rGO was examined in sulfuric acid solution using rotating disk electrode system. Figure 1 shows TEM image of synthesized IrO2 / N-rGO catalysts. The IrO2 nanoparticles with an average particle size of 1.2 nm are uniformly dispersed on surface of the N-rGO substrate. The loading amount of the IrO2 nanoparticles and doping weight of nitrogen atom of the IrO2 / N-rGO catalysts are approximately 9 and 7 wt%, respectively, which was estimated from EDX measurements. Figure 2 shows the results of XPS investigation on GO, N-rGO, and IrO2 / N-rGO. The XPS data reveal nitrogen doping on GO by hydrothermal synthesis of GO with urea. After the reaction between Ir complexes and N-rGO, Ir 4f peak appeared on the spectrum and intensity of O 1s was decreased due to reduction of GO during the hydrothermal reaction. Deconvolution analysis of the N 1s peak of N-rGO indicates doped nitrogen has three different types, pyridinic, pyrrolic, and graphitic type. The binding energy of the Ir 4f peak was shifted to a lower energy state. In addition, XRD pattern of the IrO2 / N-rGO catalyst suggests that the interlayer distance of graphene sheets decreased during hydrothermal reaction because of reduction of GO. The XRD data suppot the results of the XPS measurement. Figure 3 shows linear sweep voltammogram of the IrO2 / N-rGO catalyst obtained in 0.5 M H2SO4 solution. Electrochemical measurement reveals high activity of the IrO2 / N-rGO catalyst for OER, onset potential of the reaction is ca. 1.43 V and mass activity at 1.60 V is ca. 1000 A g-1. The overvoltage of the IrO2 / N-rGO catalysts is 70 mV lower than that of conventional IrO2 powder catalysts. High activity of the IrO2 / N-rGO catalyst indicates that the IrO2 / N-rGO catalyst is a promising candidate of anode material for PEWE. Acknowledgements This work was supported by JSPS KAKENHI Grant number 17K05969. Reference [1] M. Carmo, D. L. Fritz, J. Mergel, D. Stolten, Int. J. Hydrogen Energy 38 (2013) 4901. [2] E. Antolini, ACS Catal. 4 (2014) 1426. [3] W. S. Hummers, R. E. Offeman, J. Am. Chem. Soc. 80 (1958) 1339. Figure 1

The purpose of this study is to elucidate helium (He) retention behavior in tungsten (W) under simultaneous He and hydrogen (H) irradiation. Polycrystalline-W was irradiated by He+ and H2+ simultaneously with the energy of 1.0 keV and 3.0 keV. He+ fluences were (0.5, 1.0, 10) × 1021 He+ m−2 and H2+ fluence was 1.0 × 1022 H+ m−2,respectively. After irradiation, He desorption behavior was investigated by high temperature thermal desorption spectroscopy (HT-TDS) in the temperature range of R.T.-1773 K. Micro-structure changes of W after irradiation were observed by TEM. It was found that simultaneous irradiation with different H2+ energy significantly changed He retention behavior. 1.0 keV H2+ suppressed the He bubble growth and no bubbles can be observed at room temperature. On the other hand, 3.0 keV H2+ facilitated the formation of He bubbles and increased the He retention due to the additional damage introduction by energetic H2+.

In this research article, we report a method to fabricate conducting reduced graphene oxide (rGO) monolayer films reduced by methane plasma treatment within few minutes and the nanoscale characterization of local conductivity via conductive atomic force microscopy (C-AFM), realizing their applicability in highly transparent conducting electrodes. Continuous monolayer graphene oxide (GO) films were fabricated by a simple spin-coating method and reduction of oxygen-containing groups with simultaneous lattice defect restoration was done by methane plasma treatment. Current images obtained by C-AFM provide detailed information about the conductivity through the flakes depending on the plasma irradiation time. Moreover, lattice defect restoration was confirmed by the appearance of the G’-band in Raman spectra, which is in correlation with current images, whereas no G’-band or current image was observed in vacuum annealed samples at similar durations in the absence of methane. This rapid and facile method offers a way to fabricate conductive monolayer rGO films by a short-term plasma treatment allowing to utilize low melting point substrates to form flexible conductive graphene-based films.

Non-destructive methods to measure tritium in solids are required for material studies and managements of tritium-contaminated material in the field of fusion research. The beta particle generated by tritium decay cannot usually escape from solids. Namely, the beta particle of tritium decay is difficult to detect in solids. Conversely, the X-rays induced by beta particles in solids escape from the solid, and they can then be detected outside the solid. This is the basis of beta-ray induced X-ray (BIX) spectrometry (BIXS) of tritium. BIXS has potential for quantitative tritium analysis, but it is qualitative rather than quantitative for the solid phase. Because the number and energy of detected X-ray photons depend on the distribution of tritium in the solid, the shape of the BIX spectrum reflects the tritium distribution in the solid. For a quantitative tritium analysis, the tritium distribution in the solid would be evaluated by the shape of the BIX spectrum. In this study, Monte Carlo simulations were employed to determine the change in the BIX spectrum with the tritium depth. The relative intensity of the characteristic X-ray had the information about the tritium distribution and constituent elements of both a solid and an atmosphere. However, the change in the BIX spectrum with the tritium depth depended on the solid material. To consider the BIX spectrum of an unknown solid sample containing tritium, Monte Carlo simulation of the BIX spectrum is indispensable.

In this study, the cracking behavior and microstructural, mechanical and thermal characteristics of tungsten–rhenium (W–Re) binary alloys fabricated by laser powder bed fusion (L-PBF) were investigated. Four bulk specimens were prepared by L-PBF: pure W, W–1%Re, W–3%Re and W–10%Re (percentages indicate the mass percent of Re). High-density bulk specimens (relative density > 98.0%) were obtained for pure W and W–Re alloys under the same laser irradiation conditions. The columnar grains elongated along the building direction were gradually refined as the Re content increased. The most remarkable grain refinement was observed for the W–10%Re alloy. Hardness under a high-temperature environment increased with increasing Re content; the micro-Vickers hardnesses of pure W and W–10%Re at 400 °C were 179 ± 4 HV0.1/30 and 281 ± 5 HV0.1/30, respectively. Observations with a scanning electron microscope revealed that the 10 mass% Re addition resulted in a shorter and narrower crack morphology in comparison with pure W and consequently reduced crack area by 59%. Furthermore, the anisotropy of the thermal diffusivity was mitigated in the high Re content specimens, suggesting that, at high Re content, thermal diffusivity is affected less by cracks than by the effect of Re atoms on heat carrier transfer via isotropic scattering.

A simple sampler using a brass bar and liquid nitrogen for measuring tritium in workplaces was designed, and the suitability of the device was evaluated. The brass bar was arranged to allow its end to touch liquid nitrogen in a stainless-steel bottle, and the water vapor in the air became saturated and condensed on the surface of the brass bar. The condensation was defrosted and the tritium in the defrosted water was analyzed by a liquid scintillation counter. The data obtained with the new sampler were compared with the data obtained with a conventional modified oxidation–liquid collection sampler. The relative ratios of the data obtained with the new sampler to the data obtained with the conventional sampler were 0.64–1.54 (average 0.99, relative standard deviation 23.0%), and the new sampler showed high usefulness in working environment measurement of tritium. The data obtained with the new sampler, as the conventional sampler, showed the seasonal effect and the position dependence in the room. Thus, the applicability of the new sampler for working environment measurement of tritium was confirmed.

The conventional tritium analysis process using a liquid scintillation counter (LSC) requires over 24 h of waiting time to reduce the interference from the luminescence of the sample cocktail. The working efficiency of tritium measurement using an LSC worsens as the waiting time for luminescence decay increases. We hypothesize that this waiting time can be shortened by using light-emitting diode (LED) lamps as lighting equipment in a measurement laboratory because the emission spectra of some LED lamps contain no ultraviolet rays. Thus, a sample cocktail was prepared under an LED lamp. The count rate of this cocktail was reduced to the background of the LSC (ca. 3 cpm) within several hours. By contrast, the luminescence of a cocktail placed under daylight took approximately 100 h to decay. Therefore, the use of LED lamps is effective for luminescence control and shortening the waiting time in a measurement process.