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排序方式: 共有192条查询结果,搜索用时 15 毫秒
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Takuya Isomura Akimasa Takeuchi Kenta Shimba Kiyoshi Kotani Yasuhiko Jimbo 《Electrical Engineering in Japan》2014,187(4):42-50
Recently, there has been abundant research using multineuron recording, but there are many problems with extracting the features from the obtained spike time series, which are huge in volume and complex. Here we introduce a new method of estimating synaptic connection strengths between neurons by fitting to the Izhikevich model by maximum likelihood estimation. We demonstrate that our method can estimate connection strengths from spike time series given by a simulated neural ensemble and can estimate nonconnectivity between two independent cultured neuronal networks. These results suggest that our method is applicable to network and plasticity analysis of neuronal networks. 相似文献
3.
A new process for electrolytic production of a perfluorinated compound, (CF3)3N, using lanthanum nickel oxide-coated Ni sheet anode in the (CH3)4NF·4.0HF melt at room temperature, was developed. Thin films of the lanthanum nickel oxides were prepared on Ni sheets by sol-gel coating method using polyvinlylpyrrolidone(PVP). The main components of the thin films were La2O3, LaNiO3, and La2NiO4 at 500, 750 and 1000 °C, respectively. The anode performance in the (CH3)4NF·4.0HF melt depends greatly on the main component of the thin film, and the LaNiO3-coated Ni sheet anode gives the best anode performance. The potential of LaNiO3-coated Ni sheet anode remains constant at 5.9 V during electrolysis at 20 mA·cm−2 in the (CH3)4NF·4.0HF melt for 100 h. This is because LaNiO3 and NiF3, and/or Ni2F5, the latter of which was formed during electrolysis, in the film give a high electronic conductivity to the surface film during electrolysis. The maximum mole fraction of (CF3)3N (21.4%) was obtained at 20 mA·cm−2 in (CH3)4NF·4.0HF melt using the LaNiO3-coated Ni sheet. 相似文献
4.
The CCl4 plasma treatment of polypropylene films was investigated from the viewpoint of hydrophilic surface modification using a contact-angle meter, ATR FTIR spectroscopy, and angular XPS. Hydrophilicity and chemical composition of the CCl4 plasma treatment was effective in hydrophilic modification. The advancing contact angle of water for polypropylene films was decreased from 99° to 81-7° by the CCl4 plasma treatment, and the surface energy increased from 27.2 to 38.9-67.7 mJ/m2 when the discharge current varied from 50 to 150 mA. The CCl4 plasma initiated chlorination, oxidation, and aluminum sputtering reactions. The chlorination of polypropylene films was favorable in a mild CCl4 plasma operated at discharge current of 50 mA. The oxidation and aluminum sputtering reactions were predominant over the chlorination in strong CCl4 plasmas operated at discharge currents of more than 75 mA. The chlorination initiated by the mild CCl4 plasma was restricted near the film surface within 36 Å deep. The regions modified with the strong CCl4 plasma reached inner layers of 36-49 Å deep. Hydrophilicity caused by the CCl4 plasma treatment may be due not only to chlorine functionalities but also to oxygen and aluminum functionalities. © 1993 John Wiley & Sons, Inc. 相似文献
5.
Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations 总被引:18,自引:0,他引:18
M. Cai P. K. Kaiser Y. Tasaka T. Maejima H. Morioka M. Minami 《International Journal of Rock Mechanics and Mining Sciences》2004,41(5):833-847
The rock mass failure process is characterized by several distinct deformation stages which include crack initiation, crack propagation and coalescence. It is important to know the stress levels associated with these deformation stages for engineering design and practice.Extensive theoretical, experimental and numerical studies on the failure process of intact rocks exist. It is generally understood that crack initiation starts at 0.3 to 0.5 times the peak uniaxial compressive stress. In confined conditions, the constant-deviatoric stress criterion was found to describe the crack initiation stress level.Here, generalized crack initiation and crack damage thresholds of rock masses are proposed. The crack initiation threshold is defined by σ1−σ3=A σcm and the crack damage threshold is defined by σ1−σ3=B σcm for jointed rock masses, where A and B are material constants and σcm is the uniaxial compressive strength of the rock masses. For a massive rock mass without joints, σcm is equal to σcd, the long-term uniaxial strength of intact rock. After examining data from intact rocks and jointed rock masses, it was found that for massive to moderately jointed rock masses, the material constants A and B are in the range of 0.4 to 0.5, 0.8 to 0.9, respectively, and for moderately to highly jointed rock masses, A and B are in the range of 0.5 to 0.6, 0.9 to 1.0, respectively. The generalized crack initiation and crack damage thresholds, when combined with simple linear elastic stress analysis, assist in assessing the rock mass integrity in low confinement conditions, greatly reducing the effort needed to obtain the required material constants for engineering design of underground excavations. 相似文献
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7.
Tomohiro Isogai Kazuhiro Hirooka Tetsuro Tojo Hitoshi Takebayashi Morihiro Saito Minoru Inaba Akimasa Tasaka 《Electrochimica acta》2011,56(12):4425
Metal fluoride added carbon anodes treated by pre-electrolysis were investigated for electrolytic production of nitrogen trifluoride (NF3) in molten NH4F·KF·4HF at 100 °C. The conditions for pre-electrolysis were first optimized using a graphite sheet anode as a model anode. The formation of fluorine-graphite intercalation compounds (fluorine-GICs) with semi-covalent C–F bonds, (CxF)n, on the MgF2 and CaF2 added carbon anode surface was accelerated by pre-electrolysis at potentials less than 4.0 V. Critical current densities (CCD) on the MgF2 added carbon anodes pre-electrolyzed under various conditions were determined, and the highest CCD was 290 mA cm−2 obtained for that pre-electrolyzed at 3.5 V for 500 C cm−2. This anode was successfully used in the electrolysis at 100 mA cm−2 for 290 h and the maximum NF3 current efficiency was 55%. From these results, it was concluded that the metal fluoride added carbon anode treated by pre-electrolysis has a high potential for electrolytic production of NF3 at higher current density. 相似文献
8.
Makoto Togo Akimasa TakamuraTatsuya Asai Hirokazu KajiMatsuhiko Nishizawa 《Journal of power sources》2008
An enzyme-based glucose/O2 biofuel cell was constructed within a microfluidic channel to study the influence of electrode configuration and fluidic channel height on cell performance. The cell was composed of a bilirubin oxidase (BOD)-adsorbed O2 cathode and a glucose anode prepared by co-immobilization of glucose dehydrogenase (GDH), diaphorase (Dp) and VK3-pendant poly-l-lysine. The consumption of O2 at the upstream cathode protected the downstream anode from interfering O2 molecules, and consequently improved the cell performance (maximum cell current) ca. 10% for the present cell. The cell performance was also affected by the channel height. The output current and power of a 0.1 mm-height cell was significantly less than those of a 1 mm-height cell because of the depletion of O2, as determined by the shape of the E–I curve at the cathode. On the other hand, the volume density of current and power was several times higher for the narrower cell. 相似文献
9.
Thin films plasma-polymerized from tetramethyltin was applied for CO gas sensor device. The films formed from tetramethyltin contains alkyl chains with organic tin moieties, and pyrolysis of them at 350–500°C yields carbonized films with SnO2 moieties. The electrical resistance for the films pyrolized at 350–500°C decreases in exposing to CO gas. The sensitivity, the ratio of the electrical resistance between in air and in CO atmosphere, is enhanced by catalytic actions of palladium chloride, specially in operation at low temperatures below 50°C. The gas sensitivity between CO and other gases such as ethanol, methane, and propane gases is good. The possible determination of CO gas concentration by the sensor device is in ranges from 10 to 1000 ppm. 相似文献
10.
Mechanism‐Based Trapping of the Quinonoid Intermediate by Using the K276R Mutant of PLP‐Dependent 3‐Aminobenzoate Synthase PctV in the Biosynthesis of Pactamycin 下载免费PDF全文
Akane Hirayama Dr. Akimasa Miyanaga Prof. Dr. Fumitaka Kudo Prof. Dr. Tadashi Eguchi 《Chembiochem : a European journal of chemical biology》2015,16(17):2484-2490
Mutational analysis of the pyridoxal 5′‐phosphate (PLP)‐dependent enzyme PctV was carried out to elucidate the multi‐step reaction mechanism for the formation of 3‐aminobenzoate (3‐ABA) from 3‐dehydroshikimate (3‐DSA). Introduction of mutation K276R led to the accumulation of a quinonoid intermediate with an absorption maximum at 580 nm after the reaction of pyridoxamine 5′‐phosphate (PMP) with 3‐DSA. The chemical structure of this intermediate was supported by X‐ray crystallographic analysis of the complex formed between the K276R mutant and the quinonoid intermediate. These results clearly show that a quinonoid intermediate is involved in the formation of 3‐ABA. They also indicate that Lys276 (in the active site of PctV) plays multiple roles, including acid/base catalysis during the dehydration reaction of the quinonoid intermediate. 相似文献