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排序方式: 共有2273条查询结果,搜索用时 15 毫秒
81.
82.
Che‐Yi Lin Chao‐Fu Chen Yuan‐Ming Chang Shih‐Hsien Yang Ko‐Chun Lee Wen‐Wei Wu Wen‐Bin Jian Yen‐Fu Lin 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(33)
Electrical contacts often dominate charge transport properties at the nanoscale because of considerable differences in nanoelectronic device interfaces arising from unique geometric and electrostatic features. Transistors with a tunable Schottky barrier between the metal and semiconductor interface might simplify circuit design. Here, germanium nanowire (Ge NW) transistors with Cu3Ge as source/drain contacts formed by both buffered oxide etching treatments and rapid thermal annealing are reported. The transistors based on this Cu3Ge/Ge/Cu3Ge heterostructure show ambipolar transistor behavior with a large on/off current ratio of more than 105 and 103 for the hole and electron regimes at room temperature, respectively. Investigations of temperature‐dependent transport properties and low‐frequency current fluctuations reveal that the tunable effective Schottky barriers of the Ge NW transistors accounted for the ambipolar behaviors. It is further shown that this ambipolarity can be used to realize binary‐signal and data‐storage functions, which greatly simplify circuit design compared with conventional technologies. 相似文献
83.
Modularization strategy for syngas generation in chemical looping methane reforming systems with CO2 as feedstock 下载免费PDF全文
Peter Sandvik Fanhe Kong Yitao Zhang Abbey Empfield Liang‐Shih Fan 《American Institute of Chemical Engineers》2017,63(8):3343-3360
This study considers a CO2 feedstock in conventional methane reforming processes and metal oxide lattice oxygen based chemical looping reforming. Lattice oxygen from iron‐titanium composite metal oxide provides the most efficient co‐utilization of CO2 with CH4. A modularization chemical looping strategy is developed to further improve process efficiencies using a thermodynamic rationale. Modularization leverages the ability of two or more reactors operating in parallel to produce a higher quality syngas than a single reactor operating alone while offering a direct solution to scale up of multiple parallel reactor processes. Experiments conducted validate the thermodynamic simulation results. Simulation and experimental results ascertain that a cocurrent moving bed in a modularization system can operate under CO2 neutral or negative conditions. The results for a modularization process system for 7950 m3 per day (50,000 barrels per day) of liquid fuel indicate a ~23% reduction of natural gas usage over baseline‐case. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3343–3360, 2017 相似文献
84.
Zhao-Jun Pan Ya-Chi Nien Yu-An Shih Tsun-Ying Chen Wen-Dar Lin Wen-Hsi Kuo Hao-Chun Hsu Shih-Long Tu Jen-Chih Chen Chun-Neng Wang 《International journal of molecular sciences》2022,23(4)
The establishment of dorsal–ventral (DV) petal asymmetry is accompanied by differential growth of DV petal size, shape, and color differences, which enhance ornamental values. Genes involved in flower symmetry in Sinningia speciosa have been identified as CYCLOIDEA (SsCYC), but which gene regulatory network (GRN) is associated with SsCYC to establish DV petal asymmetry is still unknown. To uncover the GRN of DV petal asymmetry, we identified 630 DV differentially expressed genes (DV-DEGs) from the RNA-Seq of dorsal and ventral petals in the wild progenitor, S. speciosa ‘ES’. Validated by qRT-PCR, genes in the auxin signaling transduction pathway, SsCYC, and a major regulator of anthocyanin biosynthesis were upregulated in dorsal petals. These genes correlated with a higher endogenous auxin level in dorsal petals, with longer tube length growth through cell expansion and a purple dorsal color. Over-expression of SsCYC in Nicotiana reduced petal size by regulating cell growth, suggesting that SsCYC also controls cell expansion. This suggests that auxin and SsCYC both regulate DV petal asymmetry. Transiently over-expressed SsCYC, however, could not activate most major auxin signaling genes, suggesting that SsCYC may not trigger auxin regulation. Whether auxin can activate SsCYC or whether they act independently to regulate DV petal asymmetry remains to be explored in the future. 相似文献
85.
Microsystem Technologies - Brushless dc (BLDC) motor provides many advantages such as less power consumption, small volume, good stability, larger torque and simple control. As a result, the... 相似文献
86.
A low temperature process of mixing different sizes of silicon carbide (SiC) particles with a polymer precursor was utilized to synthesize SiC pellets for potential use as inert matrix fuels (IMF) for light water reactors. The lower temperature process is required to prevent the reactions between SiC and the dispersed PuO2 fuel material. The effect of the polymer content and the cold pressing pressure on the packing of SiC particles was investigated. The effect of mixing coarse and fine SiC particles on the density and the pore size distribution was also investigated. It was found that the density and pore size distribution can be tailored by controlling the SiC size compositions, polymer content and pressing pressure at room temperature. A possible mechanism has been proposed to explain the forming of the pores with respect to the geometric arrangement between SiC particles and the polymer precursor. SEM images showed that ceria (cerium oxide) which is a PuO2 surrogate in this study, was well distributed in the pellet. 相似文献
87.
Cell cycle-dependent tumor necrosis factor apoptosis 总被引:1,自引:0,他引:1
To determine if tumor necrosis factor (TNF)-mediated apoptosis affects cells at defined stages of the cell cycle, WEHI-164/2F (WEHI) cells were synchronized at G0-G1 after 3-day cultures in medium containing RPMI 1640 and 0.5% FCS (RPMI-0.5% FCS). The arrested WEHI cells (60-75% in G0-G1) showed increased sensitivity to TNF killing, measured as 48-h 3-(5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assays, and 15-h apoptosis by propidium iodide staining and flow cytometry analysis. The TNF killing kinetics of G0-G1-arrested cells was similar to controls, and TNF did not accelerate or retard cell cycle progression of the arrested cells after feeding with fresh RPMI-0.5% FCS. However, TNF inhibited WEHI DNA synthesis as early as 1 h after treatment, and inhibition was proportionate to sensitivity to TNF-induced apoptosis. WEHI cells treated with TNF showed a higher percentage of cells in S phase with concomitant decrease in G0-G1 and G2-M. When cultured for 3-18 h in fresh RPMI-0.5% FCS to allow progression of the G0-G1-arrested cells toward the G1-S boundary, WEHI cells became more sensitive to TNF killing, especially at the 3-9 h time points. Moreover, TNF did not degrade [125I]5-iodo-2'-deoxyuridine-labeled WEHI DNA if the labeled cells were precultured for 9 h in fresh RPMI-0.5% FCS to allow them to pass S phase before the addition of TNF. These results show that TNF-induced apoptosis of WEHI cells is connected to cell cycle events; WEHI targets receive the TNF cytotoxic signal mainly at the G1-S boundary and begin to die by apoptosis as they exit from S phase. 相似文献
88.
89.
The syngas chemical looping process coproduces hydrogen and electricity with iron oxide based oxygen carriers in a circulating moving bed system. In this article, a one‐dimensional (1‐D) dynamic model is developed to simulate the countercurrent gas–solid reactive flow in the moving‐bed reducer. This model is validated by TGA and bench‐scale experiments. Both the steady state and dynamic composition profiles are obtained to help understand the reaction and reactor behaviors. Numerical simulation on the effects of reactor length is conducted to optimize the moving‐bed reducer design. It is also found that minor variations in the feed rate ratio near a critical point that is represented by the reaction equilibrium could yield a significant difference in the time required for the reactions to reach a steady‐state operation. Such a difference has an important practical implication in that the moving‐bed reducer should be designed and operated to circumvent the critical point. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3432–3443, 2013 相似文献
90.
Chiou‐Juy Chen Hsu‐Tung Lu Wen‐Yen Tseng I‐Hsiang Tseng Shih‐Liang Huang Mei‐Hui Tsai 《应用聚合物科学杂志》2011,122(1):648-656
Polyimide (PI)/silica hybrid membranes with high contact angles were prepared through the in situ sol–gel process. The precursor, poly(amic acid) with controlled block chain length, was synthesized using 4,4′‐diaminodiphenyl ether (ODA), 3,3′,4,4′‐benzophenone‐tetracarboxylic dianhydride (BTDA) and 3‐aminopropyl‐trimethoxysilane (APrTMOS) or 3‐aminopropyldimethylethoxysilane (APDiMOS). And then, phenyltrimethoxysilane (PTS) or tetramethoxysilane (TMOS) or methyltrimethoxysilane (MTrMOS) was respectively, added to the above polyamic acid and mixed thoroughly. Following curing reaction, the PI/silica hybrid membranes with different cross‐linkages, silica content, and hydrophobic properties were prepared. The effect on the formation of PI imide ring during imidization reaction is increased as the increase of silanes content and characterized by frequency shiftment and absorbance ratio of Fourier transform infrared (FTIR) measurements. All the hybrid membranes show high transparency though with high silica contents. The storage modulus, tan δ, and damping intensity by DMA measurements are all correlated with silane content or block chain length. And all these membranes with silane content possess high contact angle as compared to pure PI without any silanes added and the contact angles increase with increasing the silane content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献