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Search Results: 1 - 10 of 33635 matches for " Ke Dong "
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The application of glyoxal-bis-(2-hydroxyanil) to the determination of trace amounts of cadmium by spectrofluorimetry
Dong, Yanjie;Gai, Ke;
Journal of the Brazilian Chemical Society , 2006, DOI: 10.1590/S0103-50532006000100019
Abstract: the fluorescent reaction of the reagent glyoxal-bis-(2-hydroxyanil) (gbha) with cadmium was studied. based on this chelation reaction, a sensitive, rapid, direct spectrofluorimetric method for the determination of trace cadmium with gbha has been developed. the reaction conditions for the fluorescence system of cadmium with gbha were established. the cadmium ion can form a stable chelate with gbha, having a ratio of 1:3 in the 12.0 -13.0 ph range. the maximum excitation and emission wavelengths are 227.4 nm and 320.0 nm for the cadmium chelate, respectively. the fluorescence intensity of the cadmium chelate remains stable from 20 to 150 min. under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 1.0-10.0 ng ml-1 of cadmium and the detection limit is 0.65 ng ml-1 of cadmium. interferences of foreign ions were studied. the method has been successfully applied to the determination of cadmium in the sewage.
The application of glyoxal-bis-(2-hydroxyanil) to the determination of trace amounts of cadmium by spectrofluorimetry
Dong Yanjie,Gai Ke
Journal of the Brazilian Chemical Society , 2006,
Abstract: The fluorescent reaction of the reagent glyoxal-bis-(2-hydroxyanil) (GBHA) with cadmium was studied. Based on this chelation reaction, a sensitive, rapid, direct spectrofluorimetric method for the determination of trace cadmium with GBHA has been developed. The reaction conditions for the fluorescence system of cadmium with GBHA were established. The cadmium ion can form a stable chelate with GBHA, having a ratio of 1:3 in the 12.0 -13.0 pH range. The maximum excitation and emission wavelengths are 227.4 nm and 320.0 nm for the cadmium chelate, respectively. The fluorescence intensity of the cadmium chelate remains stable from 20 to 150 min. Under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 1.0-10.0 ng mL-1 of cadmium and the detection limit is 0.65 ng mL-1 of cadmium. Interferences of foreign ions were studied. The method has been successfully applied to the determination of cadmium in the sewage.
Swarm Intelligence in Power System Planning  [PDF]
Ke Meng, Z.Y. Dong, Yichen Qiao
International Journal of Clean Coal and Energy (IJCCE) , 2013, DOI: 10.4236/ijcce.2013.22B001
Abstract: Power system planning is one of the essential tasks in the power system operation management, which requires in-depth knowledge of the system under consideration. It can be regarded as a nonlinear, discontinuous, constrained multi objective optimization problem. Although the traditional optimization tools can be used, the modern planning problem requires more advanced optimization tools. In this paper, a survey of state-of-the-art mathematical optimization methods that facilitates power system planning is provided, and the needs of introducing swarm intelligence approaches into power system planning are discussed.
Carrying capacity of red-crowned cranes in the national Yancheng rare birds Nature Reserve,Jiangsu Province,China
江苏盐城国家级珍禽自然保护区丹顶鹤的承载力

DONG Ke,
董科

生态学报 , 2005,
Abstract: The coastal-zone wetland in Yancheng,Jiangsu Province is the largest winter habitat of the Red-crowned Crane(Grus japonensis) in the world.At present,about 2700 Red-crowned Cranes live over the globe.Each year,nearly half of the Red-crowned Crane population fly to Yancheng to spend the winter.Accordingly,the environmental condition of the wetland for protection of this species is of highest significance.The essential question is: How many Cranes can be accommodated there? The carrying capacity of this habit...
Measurement of Grain Growth in Nanocrystalline Materials by Means of Differential Scanning Calorimetry
Measurement of Grain Growth in Nanocrystalline Materialsby Means of Differential Scanning Calorimetry

Ke LU,Zhenfu DONG,

材料科学技术学报 , 1997,
Abstract: In this work, we demonstrated that the differential scanning calorimetry (DSC) is not always reliable in measuring thermal stability and grain growth process in nanocrystalline materials by a quantitative analysis and comparison of the DSC data measured in nanocrystalline Ni-P and Hf-Ni samples.
Effect of Magnesium Hydride on the Corrosion Behavior of Pure Magnesium in 0.1?M NaCl Solution
Shanna Xu,Junhua Dong,Wei Ke
International Journal of Corrosion , 2010, DOI: 10.1155/2010/934867
Abstract: The effect of magnesium hydride on the corrosion behavior of pure magnesium in 0.1?M NaCl solution was investigated using the gas collection method, potentiostatic current decay test, and in situ Raman spectrum. The formation of magnesium hydride (Mg , ) was observed at the cathodic region. Applying anodic potential leads to decomposition of magnesium hydride. Magnesium hydride plays an important role on the negative difference effect (NDE) in both the cathodic and anodic regions. 1. Introduction Magnesium is one of the lightest metals and its alloys have quite favorable properties which lead to specific applications. In particularly, their high strength to weight ratio makes magnesium alloys extremely attractive for applications requiring light weight, such as transport and aerospace. However, magnesium alloys currently are still not as popular as aluminum alloys due to their poor corrosion resistant performance. Magnesium exhibits a very strange electrochemical phenomenon known as the negative difference effect (NDE) [1, 2]. Electrochemistry classifies corrosion reactions into anodic and cathodic processes. Normally, increasing the applied potential, the anodic reaction rate increases while the cathodic reaction rate decreases. Therefore for most metals like iron, steels, and zinc, and so forth, increasing the applied anodic potential will cause an increase of the anodic dissolution rate and simultaneously a decrease of the cathodic hydrogen evolution rate. However, the hydrogen evolution behavior on magnesium is quite different from that on iron and steels. Above the free corrosion potential, the hydrogen evolution rate increases with the increase of the applied nobler potential. Such behavior seems to be contradiction with the very basics of the electrochemical theory. NDE has been found on magnesium and aluminum, which are thermodynamically active [3]. The NDE is of critical importance for the corrosion of magnesium [4, 5], including galvanic corrosion [6, 7] and stress corrosion cracking [8, 9]. Recently, the conception of NDE was extended to cathodic region by Song et al. [9]. Five typical models about NDE have been proposed: (a) partially protective surface film model; (b) monovalent magnesium ion model; (c) particle undermining model; (d) magnesium hydride model; (e) integration model which combines (a), (b), and (c). Thermodynamic data shows that the magnesium hydride could exist on an electrode surface [1]. The magnesium hydride could make a contribution to the NDE. Moreover, magnesium hydride could also reduce the mechanic strength of AZ91
Review: Introduction to atmospheric corrosion research in China
Junhua Dong, Enhou Han and Wei Ke
Science and Technology of Advanced Materials , 2007,
Abstract: In this paper, we introduce the research on atmospheric corrosion in China. We describe the climate characteristics and the classification of atmospheric corrosivity across the whole country. We also describe the rusting evolution under simulated wet/dry cyclic conditions.
Time series of Internet AS-level topology graphs: four patterns and one model
Lian-dong Liu,Ke Xu
Computer Science , 2008,
Abstract: Researchers have proposed a variety of Internet topology models. However almost all of them focus on generating one graph based on one single static source graph. On the other hand, Internet topology is evolving over time continuously with the addition and deletion of nodes and edges. If a model is based on all the topologies in the past, instead of one of them, it will be more accurate and closer to the real world topology. In this paper, we study the Internet As-level topology time-series from two different sources and find that both of them obey four same dynamic graph patterns. Then we propose a mode that can infer the topology in the future based on all the topologies in the past. Through theoretical and experimental analysis, we prove the topology that our model generates can match both the static and dynamic graph patterns. In addition, the parameters in the model are meaningful. Finally, we theoretically and experimentally prove that these parameters are directly related to some important graph characteristics.
A Double AR Model Without Intercept: an Alternative to Modeling Nonstationarity and Heteroscedasticity
Dong Li,Shaojun Guo,Ke Zhu
Statistics , 2015,
Abstract: This paper presents a double AR model without intercept (DARWIN model) and provides us a new way to study the non-stationary heteroskedastic time series. It is shown that the DARWIN model is always non-stationary and heteroskedastic, and its sample properties depends on the Lyapunov exponent. An easy-to-implement estimator is proposed for the Lyapunov exponent, and it is unbiased, strongly consistent and asymptotically normal. Based on this estimator, a powerful test is constructed for testing the stability of the model. Moreover, this paper proposes the quasi-maximum likelihood estimator (QMLE) for the DARWIN model, which has an explicit form. The strong consistency and asymptotical normality of the QMLE are established regardless of the sign of the Lyapunov exponent. Simulation studies are conducted to assess the performance of the estimation and testing and an empirical example is given for illustrating the usefulness of the DARWIN model.
CRDB: Database of Chemosensory Receptor Gene Families in Vertebrate
Dong Dong, Ke Jin, Xiaoli Wu, Yang Zhong
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031540
Abstract: Chemosensory receptors (CR) are crucial for animals to sense the environmental changes and survive on earth. The emergence of whole-genome sequences provides us an opportunity to identify the entire CR gene repertoires. To completely gain more insight into the evolution of CR genes in vertebrates, we identified the nearly all CR genes in 25 vertebrates using homology-based approaches. Among these CR gene repertoires, nearly half of them were identified for the first time in those previously uncharacterized species, such as the guinea pig, giant panda and elephant, etc. Consistent with previous findings, we found that the numbers of CR genes vary extensively among different species, suggesting an extreme form of ‘birth-and-death’ evolution. For the purpose of facilitating CR gene analysis, we constructed a database with the goals to provide a resource for CR genes annotation and a web tool for exploring their evolutionary patterns. Besides a search engine for the gene extraction from a specific chromosome region, an easy-to-use phylogenetic analysis tool was also provided to facilitate online phylogeny study of CR genes. Our work can provide a rigorous platform for further study on the evolution of CR genes in vertebrates.
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