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Fengcheng, China

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Fengcheng, China

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Cui S.-W.,Normal University | Zhu R.-Z.,CAS Institute of Mechanics | Wang X.-S.,Henan Polytechnic University | Yang H.-X.,CangZhou Normal University Library | And 2 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2015

Theoretical analyses are given to the known approaches of nano-contact angle and arrive at the conclusions: 1) All the approaches based on the assumptions of Qusi-uniform liquid film, or uniform liquid molecular density, or uniform liquid molecular densities respectively inside and outside the interface layer cannot give the correct nano-contact angle, and it is difficult to improve them. Among these approaches, both the conclusions of nano-contact angle sure being 0° and sure being 180° are false. 2) Density functional theory (DFT) approach and Molecular Dynamics (MD) approach are capable to treat of nano-contact angle, however, the work is very heavy for using the DFT approach. 3) In 1995, Ruzeng Zhu (College Physic [Vol. 14 (2), p1-4 (in Chinese)], corrected the concept of contact angle in a earlier false theory for macro contact angle and obtained the most simple and convenient approximate formula of nano-contact angle α = (1-2EPS/EPL) π, where EPL is the potential of a liquid molecule in the internal liquid and EPS is the interact potential between a liquid molecule and the solid on which it locats. Both EPS and EPL can be obtained by MD, therefore this theory as a approximate simplified form belongs to Molecular Dynamics approach of nano-contact angle. The results of 0° and 180° for complete wetting and complete non-wetting given by this formula are correct under the assumption of incompressible fluid, therefore, this theory is worthy of further development. For this end, based on the physical analysis, we assume that the potential energy of a liquid molecule on the Gibss surface of tension outside the three-phase contact area is EPL/2x and that of a liquid molecule on the three-phase contact line is (1+kEPS/EPL) αEPL/2xπ, where x and k are optimal parameters. According to the condition that the potential energy is the same everywhere on the Gibss surface of tension, an improved approximate formula for nano-contact angle α = π (1-2xEPS/EPL)/(1+kEPS/EPL) is obtained. To obtain the value of x and k, MD simulations are carried on argon liquid cylinders placed on the solid surface under the temperature 90 K, by using the lennard - Jones (LJ) potentials for the interaction between liquid molecules and for that between a liquid molecule and a solid molecule with the variable coefficient of strength a. Eight values of a between 0.650 and 0.825 are used. The Gibss surfaces of tension are obtained by simulations and their bottom angles are treated as the approximate nano-contact angles. Combining these data with the physical conditions (when EPS/EPL = 0, α=π), the optimized parameter values x=0.7141, k=1.6051 with the correlation coefficient 0.9997 are obtained by least square method. This correlation coefficient close enough to 1 indicates that for nano liquid solid contact system with different interaction strength, the parameter of optimization x and k really can be viewed as constants, so that our using MD simulation to determine of the optimized parameters is feasible and our approximate formula is of general applicability. ©, 2015, Chinese Physical Society. All right reserved.


Home > Press > Quantum effects affect the best superconductor: Quantum effects explain why hydrogen sulphide is a superconductor at record-breaking temperatures Abstract: The theoretical results of a piece of international research published in Nature, whose first author is Ion Errea, a researcher at the UPV/EHU and DIPC, suggest that the quantum nature of hydrogen (in other words, the possibility of it behaving like a particle or a wave) considerably affects the structural properties of hydrogen-rich compounds (potential room-temperature superconducting substances). This is in fact the case of the superconductor hydrogen sulphide: a stinking compound that smells of rotten eggs, which when subjected to pressures a million times higher than atmospheric pressure, behaves like a superconductor at the highest temperature ever identified. This new advance in understanding the physics of high-temperature superconductivity could help to drive forward progress in the search for room-temperature superconductors, which could be used in levitating trains or next-generation supercomputers, for example. Superconductors are materials that carry electrical current with zero electrical resistance. Conventional or low-temperature ones behave that way only when the substance is cooled down to temperatures close to absolute zero (-273 °C o 0 degrees Kelvin). Last year, however, German researchers identified the high-temperature superconducting properties of hydrogen sulphide which makes it the superconductor at the highest temperature ever discovered: -70 °C or 203 K. The structure of the chemical bonds between atoms changes In classical or Newtonian physics it is possible to measure the position and momentum of a moving object to determine where it is going and how long it will take to reach its destination. These two properties are inherently linked. However, in the strange world of quantum physics, it is impossible, according to Heisenberg's uncertainty principle, for specific pairs of observable complementary physical magnitudes of a particle to be known at the same time. Hydrogen is the lightest element in the periodic table, so it is an atom that is very strongly affected by quantum behaviour. Its quantum nature affects the structural and physical properties of various hydrogen compounds. An example is high-pressure ice where quantum fluctuations of the proton lead to a change in the way the molecules are held together, due to the fact that the chemical bonds between atoms end up being symmetrical. The researchers in this study believe that a similar quantum hydrogen-bond symmetrisation occurs in the hydrogen sulphide superconductor. The researchers have formulated the calculations by considering the hydrogen atoms as quantum particles behaving like waves, and they have concluded that they form symmetrical bonds at a pressure similar to that used experimentally by the German researchers. So they have succeeded in explaining the phenomenon of superconductivity at record-breaking temperatures because in previous calculations hydrogen atoms were treated as classical particles, which made impossible to explain the experiment. All this highlights the fact that quantum physics and symmetrical hydrogen bonds lie behind high-temperature conductivity in hydrogen sulphide. The researchers are delighted that the good results obtained in this research show that quantitative predictions and computation can be used with complete confidence to speed up the discovery of high-temperature superconductors. According to the calculations made, the quantum symmetrisation of the hydrogen bonds has a great impact on the vibrational and superconducting properties of hydrogen sulphide. "In order to theoretically reproduce the observed pressure dependence of the superconducting critical temperature, the quantum symmetrisation needs to be taken into account," explained Ion Errea, the lead researcher in the study. This theoretical study shows that in hydrogen-rich compounds, the quantum motion of hydrogen can strongly affect the structural properties (even modifying the chemical bonding), as well as the electron-phonon interaction that drives the superconducting transition. In the view of the researchers, theory and computation have played a key role in the search for superconducting hydrides subjected to extreme compression. And they also pointed out that in the future an attempt will be made to increase the temperature until room-temperature superconductivity is achieved while dramatically reducing the pressures required. ### Additional information This international research was carried out with the collaboration of researchers from the UPV/EHU-University of the Basque Country and Donostia International Physics Center (DIPC), the UPMC Université Paris 06 (Sorbonne), the University of Cambridge (Cavendish Laboratory), the Jiangsu Normal University, the Carnegie Institution of Washington, Jilin University, and the University of Rome 'La Sapienza'. The lead researcher in the study was Ion Errea (Donostia-San Sebastian, 1984); he is a PhD holder in Physics and is currently a researcher at DIPC and a lecturer in the UPV/EHU's Department of Applied Physics. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Zhenhua C.,Normal University | Zhenhua C.,Xi'an University of Science and Technology | Shundong L.,Normal University | Qianhong W.,Beihang University | Qiong H.,South China Agricultural University
Security and Communication Networks | Year: 2015

In this paper, a distributed secret share update scheme with public verifiability for ad hoc network is proposed, in which the system secret key is collaboratively generated by k nodes or more, instead of by a centralized key generation center. To prevent a passive adversary from collecting other nodes' shares to compromise the system key over a long period, each node can periodically refresh its share without changing the system key. At the same time, to resist an active adversary to forge partial share and even to solve the accusation problem, any one can publicly verify the correctness of partial shares submitted by other nodes in the share update phase. To achieve our goals, we explore the technique of verifiable encryption with additive homomorphism and that of threshold cryptography. The analysis shows that the proposed scheme is more secure and efficient than the previous schemes for ad hoc networks. © 2014 John Wiley & Sons, Ltd.


News Article | January 18, 2016
Site: www.nanotech-now.com

Home > Press > TSRI researchers develop versatile new way to build molecules Abstract: Chemists at The Scripps Research Institute (TSRI) have devised a new and widely applicable technique for building potential drug molecules and other organic compounds. The new method, reported in the January 15, 2016 issue of the journal Science, enables researchers to add clusters of atoms called carbon fragment or functional groups to certain organic molecules more efficiently, robustly and selectively than current methods typically allow. It thus opens up new possibilities for chemists to assemble novel compounds that can be tested for useful properties in the development of drugs and other products. "We demonstrated this technique with two broad classes of compounds, aldehydes and ketones--the 'bread and butter' of modern chemical synthesis," said senior investigator Jin-Quan Yu, the Frank and Bertha Hupp Professor of Chemistry at TSRI. Expanding the Toolkit Yu's laboratory specializes in the development of techniques to make molecule-building easier, particularly for chemists trying to devise potential new drugs. Yu and his team have published more than a half-dozen of these innovations in Science or Nature in the past two years alone. Their newest tool improves a basic molecule-building operation called C-H functionalization. When chemists set out to build a candidate drug molecule, they often start with a simple organic compound whose central structure contains more inert carbon hydrogen bonds than reactive carbon heteroatom bonds. Turning such a starter molecule into a useful drug typically means replacing at least one of the hydrogen atoms with a more complex cluster of atoms called a functional group. This C-H functionalization process can be tricky for a variety of reasons, and chemists often have to employ special methods to make it work. Many of these methods involve helper molecules known as "directing groups." Chemists first attach a directing group to the initial molecule they want to modify; the directing group then guides a bond-breaking catalyst, often a metal such as palladium, to the carbon-hydrogen bond that needs to be broken to make way for the new functional group. "This has proven to be a very reliable and broadly useful strategy," said Yu, "but it requires at least two additional steps--the installation of the directing group and later its removal--and sometimes the directing group is incompatible with functional groups already present on the starting molecule." Ideally, chemists would like to find directing groups that are broadly tolerant of existing functional groups and that also don't have to be attached and detached in separate steps. Essentially that is what Yu and his team have achieved here. Cutting Out Two Steps The team--including co-first authors Fang-Lin Zhang, a visiting scholar from Wuhan University of Technology; Kai Hong, a postdoctoral research associate in the Yu Laboratory; and Tuan-Jie Li, a visiting scholar from Jiangsu Normal University--found that amino acid molecules (the building blocks of the proteins that help make up all known life forms) can work well as "transient directing groups" for ketone or aldehyde compounds. The amino acids attach themselves automatically to these starter compounds and remove themselves automatically after the new functional group is attached. In effect, this means that they work "catalytically," functionalizing one starter molecule after another and continually being re-used, rather than being consumed in their first reaction. This further streamlines the process and reduces the overall quantity of reagents that are needed. "In principle, all amino acids can be used as catalytic directing groups for such reactions," said Yu. "The availability of diverse amino acids makes it possible to find different reagents to suit different substrates or transformations." A further advantage of the new technique is that it can, with the proper choice of chiral amino acid directing group, preferentially generate "chiral" molecules that are functionalized just on one side. C-H functionalization reactions typically generate a roughly even mix of molecules functionalized on one side plus mirror-image molecules functionalized on the other side--yet the desirable biological activity of a drug often comes exclusively from its "right-handed" or "left-handed" chiral form. "The fact that we can do this using a simple amino acid as the directing group and ligand is phenomenal, considering the usual difficulty of such reactions," said Hong. "Essentially with this new method we're improving functionalizations by cutting out two steps in the functionalization process--by using a directing group that is catalytic, and by employing, if needed, a chiral directing group to generate chirally pure compounds," said Yu. Yu and his team are now working to extend the applicability of the new method to other broad classes of medicinal chemistry compounds such as amines and alcohols. ### The other co-author of the paper, "Functionalization of C(sp3)-H bonds using a transient directing group," was Hojoon Park of the Yu laboratory at TSRI. The work was funded in part by the National Institute of General Medical Sciences (2R01GM084019). For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | January 14, 2016
Site: phys.org

The new method, reported in the January 15, 2016 issue of the journal Science, enables researchers to add clusters of atoms called carbon fragment or functional groups to certain organic molecules more efficiently, robustly and selectively than current methods typically allow. It thus opens up new possibilities for chemists to assemble novel compounds that can be tested for useful properties in the development of drugs and other products. "We demonstrated this technique with two broad classes of compounds, aldehydes and ketones—the 'bread and butter' of modern chemical synthesis," said senior investigator Jin-Quan Yu, the Frank and Bertha Hupp Professor of Chemistry at TSRI. Yu's laboratory specializes in the development of techniques to make molecule-building easier, particularly for chemists trying to devise potential new drugs. Yu and his team have published more than a half-dozen of these innovations in Science or Nature in the past two years alone. Their newest tool improves a basic molecule-building operation called C-H functionalization. When chemists set out to build a candidate drug molecule, they often start with a simple organic compound whose central structure contains more inert carbon hydrogen bonds than reactive carbon heteroatom bonds. Turning such a starter molecule into a useful drug typically means replacing at least one of the hydrogen atoms with a more complex cluster of atoms called a functional group. This C-H functionalization process can be tricky for a variety of reasons, and chemists often have to employ special methods to make it work. Many of these methods involve helper molecules known as "directing groups." Chemists first attach a directing group to the initial molecule they want to modify; the directing group then guides a bond-breaking catalyst, often a metal such as palladium, to the carbon-hydrogen bond that needs to be broken to make way for the new functional group. "This has proven to be a very reliable and broadly useful strategy," said Yu, "but it requires at least two additional steps—the installation of the directing group and later its removal—and sometimes the directing group is incompatible with functional groups already present on the starting molecule." Ideally, chemists would like to find directing groups that are broadly tolerant of existing functional groups and that also don't have to be attached and detached in separate steps. Essentially that is what Yu and his team have achieved here. The team—including co-first authors Fang-Lin Zhang, a visiting scholar from Wuhan University of Technology; Kai Hong, a postdoctoral research associate in the Yu Laboratory; and Tuan-Jie Li, a visiting scholar from Jiangsu Normal University—found that amino acid molecules (the building blocks of the proteins that help make up all known life forms) can work well as "transient directing groups" for ketone or aldehyde compounds. The amino acids attach themselves automatically to these starter compounds and remove themselves automatically after the new functional group is attached. In effect, this means that they work "catalytically," functionalizing one starter molecule after another and continually being re-used, rather than being consumed in their first reaction. This further streamlines the process and reduces the overall quantity of reagents that are needed. "In principle, all amino acids can be used as catalytic directing groups for such reactions," said Yu. "The availability of diverse amino acids makes it possible to find different reagents to suit different substrates or transformations." A further advantage of the new technique is that it can, with the proper choice of chiral amino acid directing group, preferentially generate "chiral" molecules that are functionalized just on one side. C-H functionalization reactions typically generate a roughly even mix of molecules functionalized on one side plus mirror-image molecules functionalized on the other side—yet the desirable biological activity of a drug often comes exclusively from its "right-handed" or "left-handed" chiral form. "The fact that we can do this using a simple amino acid as the directing group and ligand is phenomenal, considering the usual difficulty of such reactions," said Hong. "Essentially with this new method we're improving functionalizations by cutting out two steps in the functionalization process—by using a directing group that is catalytic, and by employing, if needed, a chiral directing group to generate chirally pure compounds," said Yu. Yu and his team are now working to extend the applicability of the new method to other broad classes of medicinal chemistry compounds such as amines and alcohols. Explore further: Building new drugs just got easier More information: "Functionalization of C(sp3)–H bonds using a transient directing group" DOI: 10.1126/science.aad7893


Qu J.,China Three Gorges University | Zou L.,China Three Gorges University | Zhang J.,Normal University
Proceedings 2010 IEEE International Conference on Information Theory and Information Security, ICITIS 2010 | Year: 2010

In this paper, we propose a practical dynamic multi-secret sharing scheme based on the intractability of the discrete logarithm and one way hash functions, the exclusive OR operation. Security analysis shows that our scheme could correctly reconstruct the shared secret, and our scheme is as secure as Lin-Yeh's scheme. In addition, in our schemes, all participants themselves select their shares, so the calculation amount of dealer is reduced and secure channel between the dealer and any participant is avoided. The group secret combiner can verify whether each participant's pseudo secret share true or not. © 2010 IEEE.


Xue L.,Normal University | Yi L.,Normal University
ICCET 2010 - 2010 International Conference on Computer Engineering and Technology, Proceedings | Year: 2010

With the development of computer technology, the role data acquisition system played in equipment check system is particularly prominent. Embedded-based portable data acquisition system generation makes the function of the data acquisition system further expanded. Based on the object-oriented analysis and design methods, this paper uses software reuse ideas and a unified modeling language, component technology to design the portable data acquisition system software model, and carry out a certain amount of research of the system case model, domain model, dynamic model and component model. © 2010 IEEE.


Xiong Y.,Normal University | Chen S.,Normal University | Ye F.,Normal University | Su L.,Normal University | And 3 more authors.
Chemical Communications | Year: 2015

We demonstrate a facile and rapid in situ partial oxidation synthetic strategy for the fabrication of a mixed valence state Ce-MOF (MVCM) which exhibits intrinsic oxidase-like activity. Furthermore, on the basis of the excellent catalytic activity of the MCVM, a colorimetric approach for the high-throughput detection of biothiols in serum samples was established. © 2015 The Royal Society of Chemistry.

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