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Search Results: 1 - 10 of 104410 matches for " ZHANG Dapeng "
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Projective Dirac Operators, Twisted K-Theory and Local Index Formula
Dapeng Zhang
Mathematics , 2010, DOI: 10.4171/JNCG/153
Abstract: We construct a canonical noncommutative spectral triple for every oriented closed Riemannian manifold, which represents the fundamental class in the twisted K-homology of the manifold. This so-called "projective spectral triple" is Morita equivalent to the well-known commutative spin spectral triple provided that the manifold is spin-c. We give an explicit local formula for the twisted Chern character for K-theories twisted with torsion classes, and with this formula we show that the twisted Chern character of the projective spectral triple is identical to the Poincar\'e dual of the A-hat genus of the manifold.
A Volt-Ampere Method to Estimate the Energy Efficiency Evolutions of Proton Exchange Membrane Fuel Cells along with Load and Time  [PDF]
Hongfei Zhang, Pucheng Pei, Mancun Song, Dapeng Zhang
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.52A004
Abstract:

The energy efficiency of proton exchange membrane (PEM) fuel cells always keeps changing with load and time. Considering cell diversity and operation variety, it’s of necessity to find a simple method to estimate the changes. The work is done with the recently developed ideal cell model on behalf of various real cells, and results in a complete set of efficiency formulae including one for the instantaneous and three for the average. The formulae stand for a volt-ampere method which permits the average efficiency to be estimated in the form of state function of cell output like the instantaneous efficiency. With cell constants for cell specialty representation in this method, the formulae can extend to cover various real cells and make it realized to broadly overview the instantaneous and average efficiency movements with both load and time throughout cell operating ranges. The energy efficiency formulization and overviews may help make clear the correlative parameters with the efficiency, help deepen acquaintance with efficiency change and assist in cell operation optimization.

Post-translational inhibitory regulation of acid invertase induced by fructose and glucose in developing apple fruit
Zhang Dapeng,Wang Yongzhang
Science China Life Sciences , 2002, DOI: 10.1360/02yc9034
Abstract: Acid invertase (EC 3.2.1.26) is one of the key enzymes involved in the carbohydrate sinkorgan development and the sink strength modulation in crops. The experiment conducted with ‘Starkrimson’ apple (Malus domestica Borkh) fruit showed that, during the fruit development, the activity of acid invertase gradually declined concomitantly with the progressive accumulation of fructose, glucose and sucrose, while Western blotting assay of acid invertase detected a 30 ku peptide of which the immuno-signal intensity increased during the fruit development. The immunolocalization via immunogold electron microscopy showed that, on the one hand, acid invertase was mainly located on the flesh cell wall with numbers of the immunosignals present in the vacuole at the late stage of fruit development; and on the other hand, the amount of acid invertase increased during fruit development, which was consistent with the results of Western blotting. The in vivo preincubation of fruit discs with soluble sugars showed that the activity of extractible acid invertase was inhibited by fructose or glucose, while Western blotting did not detect any changes in apparent quantity of the enzyme nor other peptides than 30 ku one. So it is considered that fructose and glucose induced the post-translational or translocational inhibitory regulation of acid invertase in developing apple fruit. The mechanism of the post-translational inhibition was shown different from both the two previously reported ones that proposed either the inhibition by hexose products in the in vitro chemical reaction equilibrium system or the inhibition by the proteinaceous inhibitors. It was hypothesized that fructose and glucose might induce acid invertase inhibition by modulating the expression of some inhibition-related genes or some structural modification of acid invertase.
β-amylase in developing apple fruits: activities, amounts and subcellular localization
Dapeng Zhang,Yongzhang Wang
Science China Life Sciences , 2002, DOI: 10.1360/02yc9048
Abstract: Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, β-amylase is considered one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. The present experiment showed that β-amylase activity was progressively increasing concomitantly with decreasing starch concentrations during apple (Malus domestica Borkh cv. Starkrimson) fruit development. The apparent amount of β-amylase assessed by Western blotting also increased during the fruit development, which is consistent with the seasonal changes in the enzyme activity. The subcellular-localization studies via immunogold electron-microscopy technique showed that β-amylase visualized by gold particles was predominantly located in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments. These data proved for the first time that the enzyme is compartmented in its functional sites in plant living cells. The predominantly plastid-distributed pattern of β-amylase in cells was shown unchanged throughout the fruit development. The density of gold particles (β-amylase) in plastids was increasing during the fruit development, which is consistent with the results of Western blotting. So it is considered that β-amylase is involved in starch hydrolysis in plastids of the fruit cells.
The Temptation of Getting the “Pie”----- The Cost-benefit Analysis on Farmer Specialized Cooperatives Access to Government Subsidies in Mainland China
Ying Zhang,Dapeng Ren
International Journal of Business and Management , 2011, DOI: 10.5539/ijbm.v6n9p24
Abstract: In the Chinese mainland, government subsidies look like a delicious “pie” hunted by different cooperatives. In order to get more charge of it, however, some cooperatives used strategies distorting the cooperative’s basic characters. These problems appeared also decline the capital usage efficiency of government subsidies in a certain extent. This paper uses transaction cost theory to explore the current situation and the cost/benefit existed in different cases. The authors believe that the win-win options for Chinese cooperatives are getting the supportive resource, developing themselves and profiting from the market as well. In the end, authors suggest that the financial subsidies should be more used on building a public service platform to realize more and more cooperatives benefiting.
beta-amylase in developing apple fruits: activities, amounts and subcellular localization
β-amylase in developing apple fruits: activities, amounts and subcellular localization

ZHANG Dapeng,WANG Yongzhang,

中国科学C辑(英文版) , 2002,
Abstract: Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, beta-amylase is considered one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. The present experiment showed that beta-amylase activity was progressively increasing concomitantly with decreasing starch concentrations during apple (Malus domestica Borkh cv. Starkrimson) fruit development. The apparent amount of beta-amylase assessed by Western blotting also increased during the fruit development, which is consistent with the seasonal changes in the enzyme activity. The subcellular-localization studies via immunogold electron-microscopy technique showed that beta-amylase visualized by gold particles was predominantly located in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments. These data proved for the first time that the enzyme is compartmented in its functional sites in plant living cells. The predominantly plastid-distributed pattern of beta-amylase in cells was shown unchanged throughout the fruit development. The density of gold particles (beta-amylase) in plastids was increasing during the fruit development, which is consistent with the results of Western blotting. So it is considered that beta-amylase is involved in starch hydrolysis in plastids of the fruit cells.
A Survey of the Development of Computers for Pattern Recognition and Image Processing(PRIP)
模式识别与图象处理(PRIP)计算机发展评述

Zhang Dapeng,
张大鹏

自动化学报 , 1989,
Abstract: In this paper, some important facts promoting the development of PRIP computers are analysed. Then the current situation, the features, and trend of the development are evaluated. And the classification with 4 types of architecture is presented. The explorations above are useful to developing PRIP computers in China.
Morphology and Thermal Characteristics of Polysaccharide Extracted by Ultrasound from Ophiopogon japonicas  [PDF]
Xiaomei Wang, Tianzhu Zhang, Wenfei Zhang, Miao Wang, Dapeng Hao, Qi Ding
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.98123
Abstract: The crude polysaccharide UPOJ was extracted by ultrasound from Ophiopogon japonicas and purified by DEAE-cellulose52 column and Sephadex G-150 gel column. Purified polysaccharide UPOJ-DS was obtained. The thermal characteristics of UPOJ-DS were studied by using the thermal analysis system Q1000DSC LNCS FACS Q600SDT. The heating rate was 10°C/min and the test temperature was 20°C ~ 800°C. The results showed that there were three large mass losses in the process of heating, in which the maximum weight loss rate was 66.68% at 220°C ~
A New Version of Special Relativity Absorbed the Uncertainty Principle: Its Content as Well as Application and Experimental Test  [PDF]
Dapeng Qian
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.512117
Abstract:

Based on the space spherical symmetry of 3-dimensional and the translational symmetry of time and the uncertainty principle, a 4-dimensional space-time cylinder model of quarks and leptons is established. With this model, equations of the special relativity can be extended more perfectly, thereby achieving a unity of the special relativity and quantum mechanics in deeper level. New equations can not only interpret issues explained by old equations but also solve several important pending problems. For example, a formula to strictly calculate the coefficient ξ of Lorentz invariance violation (LIV) is derived, to above 4 × 1019 eV UHECR protons the calculated |ξ| < 4.5 × 10-30, although there is the LIV effect it is too weak to change the GZK cutoff, which is consistent with observations of HiRes and Auger; Also, a relation formula between the Hubble constant and several basic constants is derived, thus theoretically calculated H0 = 70.937 km·s-1·Mpc-1, which is well consistent with the final observation result of HST Key Project. In addition, an unusual effect predicted by new equations can be experimentally tested in the electron storage ring; a preliminary experiment result has hinted its signs of existence.

Comparison of Y2Ba4CuBiOy Nanoparticles with CeO2 Doping on the Levitation Force of Single Domain YBCO Bulk Superconductor by TSIG Process  [PDF]
Miao Wang, Xu Yang, Xuan Wang, Xiaomei Wang, Ming Zhang, Dapeng Hao
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.61010
Abstract: The top-seeded infiltration and growth process (TSIG) is very effective method for the preparation of YBa2Cu3O7-x (YBCO) bulk superconductors. In order to improve the levitation force of the samples, a series of single domain YBCO bulk superconductors with different ratios of nanoscale Y2Ba4CuBiOy (YBi2411) inclusions in the solid phase pellet is successfully fabricated by the TSIG technique on the basis of previous research. In the present work, the results of YBCO bulk superconductors with YBi2411 and CeO2 (1 wt%) codoping system indicate that, the optimum doping of YBi2411 is 2 wt%, the size of Y211 particles is reduced compared with the samples without CeO2 doping; the largest levitation force is about 15 N obtained in the samples with optimum YBi2411, which is about two times higher than that of the sample without CeO2 doping. The results are very helpful for the fabrication of high quality single domain YBCO bulk superconductors.
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