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311.
Nickel-based single crystal superalloys oriented along the o0014 and o0114 lattice
directions were produced by a bottom seeding technique in an attempt to understand the evolution
mechanism of the dendrite grown along different orientations in the present study. The changes in
primary dendrite arm spacing for single crystal with different orientations are also discussed. It was
found that the dendrite morphologies of single crystal superalloy grown along o0114 were
different from that of o0014. Firstly, the dendrites showed the irregular cruciforms and array in
rows in a transverse section. Secondly, no typical primary dendrites were observed but the dendrite
morphologies appeared like the letter ‘‘V’’ or ‘‘W’’ in a longitudinal section. The primary dendrite
arms grew along the o0014 orientation from the bottom of the sample in the o0014 orientation.
However, in the o0114 orientation, the single crystal developed by continuous side-branching
along the [001] and [010] orientations. The primary dendrite arm spacing was as the function of the
deviation angle f. It indicates that with the increase in the deviation angle f, the primary dendrite
arm spacing first increased, and then decreased. 相似文献
312.
A facile and green preparation of high surface area activated carbons with mixed
microporosity and mesoporosity from durian shell waste is reported in this work. The pore
structure and surface chemistry of the parent carbon were modified by the combination of
ultrasonication and microwave irradiation techniques. The effects of temperature and time in the
ultrasonication treatment and power output and time in the microwave irradiation were studied.
The electrochemical performance of carbon electrodes for supercapacitors was tested by cyclic
voltammeter (CV) and galvanostatic charge–discharge. The results show that the capacitive energy
storage of electrodes is critically dependent on the microporosity and surface chemistry of activated
carbons. The highest electrode capacitance in this work was 103.6 F/g that prepared from activated
carbon modified at an ultrasonication temperature of 323.15 K for 10 min and microwave power
output of 900 W for 10 min. 相似文献
313.
Response surface methodology (RSM) is used to optimize the medium of Tetraselmis sp.-1 which is cell fused microalgae capable of growing under mixotrophie condition. Empirical models are developed to describe the relationships between the operating variables (glucose, urea, sodium dehydrogenate phosphate, sodium chloride) and responses (cell density). Statistical analysis indi-cates that glucose and urea have significant effects on the microalgae cell density, but other two factors (sodium dehydrogenate phosphate, sodium chloride) have no obvious effect. The path of steepest ascent is used to approach the optimal region of medium ecanposition. Optimal cell density(2. 638 g dry weight/L) was reached when the operating conditions were glucose concentration(30.75 % ), urea concentration (0.440 g/L), sodium dehydrogenate phosphate (15mg/L) and sodium chloride (28 g/L). 相似文献
314.
A wing specific F 1 genetic screen was carried out using the powerful Drosophila genetic system, combined with yeast FRT/FLP and GAL4/UAS system. Form the wing phenotypes and germline clone embryonic cuticle phenotypes observed in these mutant alleles, a number of mutant alleles of known or unknown genes were isolated. Among them, fifteen mutant alleles related to Wingless signal transduction were further isolated; the arm of these mutations located were determined, and their location in the chromosome were roughly mapped. 相似文献
315.
Human cytomegalovirus induces alteration of β-actin mRNA and microfilaments in human embryo fibroblast cells 总被引:4,自引:0,他引:4
Objective: To investigate the infection of human embryo fibroblast cell line HF cells by CMV as well as the effects of CMV on β-actin mRNA and microfilaments. Methods: HF cells shape was observed after the infection of CMV.RT-PCR assay was used to detect the mRNA expression of CMV immediate early (IE) gene, β-actin and GAPDH genes of HF cells infected by CMV. CMV particles and cell microfilaments were detected with electron microscope. Results: Shape of HF cell changed after the infection by CMV. HF cells infected by CMV could express IE mRNA and the expression of β-actin mRNA decreased in a time-and titer-dependent manner compared with the uninfected HF cells whose expression of GAPDH mRNA did not change much. CMV particles were found with electron microscope in the cells. Microfilaments were ruptured and shortened after the infection of CMV. Conclusion: CMV can not only infect human embryo fibroblast cells line HF cells and replicate in the cells, but can also affect the expression of β-actin mRNA and the microfilaments. 相似文献
316.
A new photonic bandgap (PBG) cover for a patch antenna with a photonic bandgap substrate is introduced. The plane wave expansion method and the FDTD method were used to calculate such an antenna system. Numerical results for the input return loss, radiation pattern, surface wave, and the directivity of the antennas are presented. A comparison between the conventional patch antenna and the new PBG antenna is given. It is shown that the new PBG cover is very efficient for improving the radiation directivity. The physical reasons for the improvement are also given. 相似文献
317.
318.
A new framework for consciousness is introduced based upon traditional artificial neural network models. This framework reflects explicit connections between two parts of the brain: one global working memory and distributed modular cerebral networks relating to specific brain functions. Accordingly this framework is composed of three layers, physical mnemonic layer and abstract thinking layer, which cooperate together through a recognition layer to accomplish information storage and cognition using algorithms of how these interactions contribute to consciousness: (1) the reception process whereby cerebral subsystems group distributed signals into coherent object patterns; (2) the partial recognition process whereby patterns from particular subsystems are compared or stored as knowledge; and (3) the resonant learning process whereby global workspace stably adjusts its structure to adapt to patterns' changes. Using this framework, various sorts of human actions can be explained, leading to a general approach for analyzing brain functions. 相似文献
319.
Study of the morphology, aggregation structure and properties of Bombyx mori silk treated by low temperature oxygen plasma showed that slight flutes appeared on the surface of Bombyx mori silk fiber and that its surface structure changed after plasma treatment. The conformation also changed and crystalline degree decreased. The stannic filling rate of treated fiber was improved. Because of etching, the weight of the fiber decreased but the breaking strength changed little after short-time treatment. 相似文献
320.
Electrochemistry: building on bubbles in metal electrodeposition 总被引:1,自引:0,他引:1
Tsai WL Hsu PC Hwu Y Chen CH Chang LW Je JH Lin HM Groso A Margaritondo G 《Nature》2002,417(6885):139
In the electrodeposition of metals, a widely used industrial technique, bubbles of gas generated near the cathode can adversely affect the quality of the metal coating. Here we use phase-contrast radiology with synchrotron radiation to witness directly and in real time the accumulation of zinc on hydrogen bubbles. This process explains the origin of the bubble-shaped defects that are common in electrodeposited coatings. 相似文献