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排序方式: 共有449条查询结果,搜索用时 15 毫秒
1.
A new, simple, and reproducible method is described for the determination of selenium(IV) based on differential pulse cathodic stripping voltammetry. The optimized experimental conditions are as follows: selenium(IV) ions in an acidic medium (0.06 M HCl-0.07 M HNO(3)) are electrodeposited on a rotating silver disk electrode as silver selenide at -0.4 V vs SCE for 30 min; the deposit is then cathodically stripped in another solution (2 M NaOH) at a scan rate of 50 mV s(-1) to -1.2 V vs SCE. The cathodic stripping results in only a single well-defined peak at about -0.95 V vs SCE. The calibration (peak height vs selenium concentration) graph is linear up to at least 40 ng mL(-1) of selenium(IV) and passes through the origin, with a relative standard deviation of 2.7% for 20 ng mL(-1) (n = 5). The detection limit (3σ) is 0.20 ng mL(-1). The possible interferences have been evaluated. Dissolved oxygen does not affect the peak height of selenium. The electrode can be used repeatedly at least 20 times with excellent reproducibility without further polishing. The proposed method is an improvement over the existing cathodic stripping techniques. 相似文献
2.
Tadao Tanabe Yuichi Kozawa Ken Suto Jun-ichi Nishizawa Ytaka Oyama 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(6):881-892
Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions. 相似文献
3.
Kailong Hu Tingting Yu Yanyi Zhang Xiaorong Lin Yilu Zhao Guoqiang Xie Xingjun Liu Xi Lin Jun-ichi Fujita Hua-Jun Qiu Yoshikazu Ito 《Advanced functional materials》2021,31(38):2103632
Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal-air batteries. A promising strategy for improving both ORR performance and mass diffusion simultaneously is to build carbon-based catalysts with ORR-active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N-doped carbon with bicontinuous porosity and interconnected open-pore channels is reported, which is prepared by a polyaniline-assisted template method. The polyaniline can efficiently inhibit the surface diffusion-caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N-dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C-comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all-solid-state flexible Al-air battery is assembled with the measured maximum power density reaching 130.5 mW cm−2, as compared to 106.2 mW cm−2 when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N-doped carbon with bicontinuous nano-sized pore channels for wide-ranging applications in portable and flexible devices. 相似文献
4.
Matsumoto S. Hiraoka Y. Ishiyama T. Sakai T. Yachi T. Yamada I. Ito A. Arimoto Y. 《Electron Devices, IEEE Transactions on》1998,45(9):1940-1945
The device characteristics of a quasi-SOI power MOSFET were investigated to obtain its optimum device structure. The oxide at the original bottom surface of the bulk power MOSFET of the quasi-SOI power MOSFET formed by reversed silicon wafer direct bonding acts as the buried oxide of the conventional SOI power MOSFET. The short channel effect of the quasi-SOI power MOSFET was larger than that in the conventional SOI power MOSFET. It was suppressed by increasing the width of the oxide in the body region, and the parasitic bipolar effect was suppressed by decreasing it. We also propose a new device structure which can suppress the short channel effect and parasitic bipolar effect of a quasi-SOI power MOSFET based on the results of these experiments 相似文献
5.
Takeo Ohno Yutaka Oyama Ken Suto Jun-ichi Nishizawa 《Materials Science in Semiconductor Processing》2003,6(5-6):417-420
Low-temperature (290°C) area-selective regrowth by molecular layer epitaxy (MLE) was applied for the fabrication of an ultra-shallow sidewall (50 nm) GaAs tunnel junction. Fabricated tunnel junctions have shown a record peak current density up to 35,000 A/cm2. It is shown that the tunnel junction characteristics are strongly dependent on the sidewall orientation and the AsH3 surface treatment conditions just prior to regrowth. The effects of AsH3 surface treatment are discussed in view of the control of surface stoichiometry. 相似文献
6.
Access and metro networks based on WDM technologies 总被引:3,自引:0,他引:3
Iwatsuki K. Jun-ichi Kani Suzuki H. Fujiwara M. 《Lightwave Technology, Journal of》2004,22(11):2623-2630
This paper describes the technical issues of access and metro networks based on wavelength division multiplexing (WDM) technologies, some solutions, and an experimental demonstration. A WDM star access network with colorless optical network units (ONUs) is proposed. For realizing the colorless ONU, two approaches are introduced; optical carrier supply and spectrum slicing. In addition, a WDM metro ring network with scalable optical add/drop multiplexers (OADMs), namely the tapped-type OADM, is proposed to effectively accommodate the large amount of traffic issued from access networks. Prototypes are constructed and used to verify the feasibility of the proposed WDM technologies. 相似文献
7.
Jun-ichi Nishizawa Akihiko Murai Hiroki Makabe Osamu Ito Tomoyuki Kimura Ken Suto Yutaka Oyama 《Solid-state electronics》2004,48(12):2251-2254
The tunnel injection transit time (TUNNETT) diodes with p+p+n+n−n+ structure were fabricated by liquid phase epitaxy (LPE). About 100 Å tunnel junction (p+n+) was successfully prepared by the double impurity diffusion of Ge and S during LPE growth. Continuous wave (CW) oscillation was realized at 51.520 GHz in the V-band cavity with the phase noise of −60 dBc/Hz at 1 kHz bandwidth. 相似文献
8.
Mutational analysis of structure--activity relationships in human tumor necrosis factor-alpha 总被引:1,自引:0,他引:1
Yamagishi Jun-ichi; Kawashima Hitoshi; Matsuo Noriyuki; Ohue Mayumi; Yamayoshi Michiko; Fukui Toshikazu; Kotani Hirotada; Furuta Ryuji; Nakano Katsuji; Yamada Masaaki 《Protein engineering, design & selection : PEDS》1990,3(8):713-719
To determine the region of human tumor necrosis factor-alpha(TNF-), essential for cytotoxic activity against mouse L-M cells,single amino-acid-substituted TNF- mutant proteins (muteins)were produced in Escherichia coli by protein engineering techniques.An expression plasmid for TNF- was mutagenized by passage throughan E.coli mutD5 mutator strain and by oligonucleotide-directedmutagenesis. Approximately 100 single amino-acid-substitutedTNF- muteins were produced and assayed for cytotoxic activity.The cytotoxic activities of purified TNF- muteins, e.g. TNF-31T,-32Y, -82D, -85H, -115L, -141Y, -144K and -146E, were < 1%of that of parent TNF-. These results indicate that the integrityof at least four distinct regions of the TNF- molecule is requiredfor full biological activity. These regions are designated asfollows: region I, from position 30 to 32; region II, from position82 to 89; region III, from position 115 to 117; region FV, fromposition 141 to 146. In addition, TNF-141Y could not completelycompete with parent TNF- for binding to the receptor. This demonstratesthat region IV, and at least aspartk acid at position 141, mustbe involved in the TNF receptor binding site. 相似文献
9.
Noritsugu Hashimoto Seiji Niijima Jun-ichi Inagaki 《Journal of the European Ceramic Society》2009,29(14):3039-3043
Solid oxide fuel cells (SOFCs) are very attractive for their high energy conversion efficiency and low emissions. Generally, a supported layer of SOFCs is fabricated by tape casting, using an organic solvent. Recently, a slurry based on water instead of an organic solvent has been sought in order to avoid environmental pollution. In this study, the anode of SOFCs was fabricated by aqueous tape casting, and the electrolyte and the cathode were deposited by screen printing. The I–V characteristics of the cell thus obtained were evaluated. As a result, an 80 mm diameter-sized cell with a power density of 0.33 W/cm2 at 800 °C was successfully fabricated by controlling sintering conditions. 相似文献
10.
Tomoya Hasegawa Mikako Ito Satoru Hasegawa Masaki Teranishi Koki Takeda Shuto Negishi Hiroshi Nishiwaki Jun-ichi Takeda Tyler W. LeBaron Kinji Ohno 《International journal of molecular sciences》2022,23(5)
Molecular hydrogen ameliorates pathological states in a variety of human diseases, animal models, and cell models, but the effects of hydrogen on cancer have been rarely reported. In addition, the molecular mechanisms underlying the effects of hydrogen remain mostly unelucidated. We found that hydrogen enhances proliferation of four out of seven human cancer cell lines (the responders). The proliferation-promoting effects were not correlated with basal levels of cellular reactive oxygen species. Expression profiling of the seven cells showed that the responders have higher gene expression of mitochondrial electron transport chain (ETC) molecules than the non-responders. In addition, the responders have higher mitochondrial mass, higher mitochondrial superoxide, higher mitochondrial membrane potential, and higher mitochondrial spare respiratory capacity than the non-responders. In the responders, hydrogen provoked mitochondrial unfolded protein response (mtUPR). Suppression of cell proliferation by rotenone, an inhibitor of mitochondrial ETC complex I, was rescued by hydrogen in the responders. Hydrogen triggers mtUPR and induces cell proliferation in cancer cells that have high basal and spare mitochondrial ETC activities. 相似文献