Modelling the spreading rate of controlled communicable epidemics through an entropy-based thermodynamic model

A model based on a thermodynamic approach is proposed for predicting the dynamics of communicable epidemics assumed to be governed by controlling eforts of multiple scales so that an entropy is associated with the system.All the epidemic details are factored into a single and time-dependent coefcient,the functional form of this coefcient is found through four constraints,including notably the existence of an inflexion point and a maximum.The model is solved to give a log-normal distribution for the spread rate,for which a Shannon entropy can be defined.The only parameter,that characterizes the width of the distribution function,is uniquely determined through maximizing the rate of entropy production.This entropy-based thermodynamic(EBT)model predicts the number of hospitalized cases with a reasonable accuracy for SARS in the year 2003.This EBT model can be of use for potential epidemics such as avian influenza and H7N9 in China.     

V2O5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

Science China Chemistry - A study of the catalytic activity of V2O5/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH...     

V2O5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

A study of the catalytic activity of V₂O₅/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH value and there is little oxalic acid from the excessive oxidation of glyoxylic acid. The studies of XRD and TEM have shown that V₂O₅ diffraction peaks gradually strengthen with the increase of the content of V₂O₅. With the content of 3% V₂O₅ and the calcination temperature of 573 K, V₂O₅/C catalyst displayed the best activity and selectivity. The conversion of glyoxal and the selectivity of glyoxylic acid reached 18.76% and 77.70% after 5 h, respectively. Moreover, V₂O₅/C catalyst showed small deactivation after recycling three times, which indicates that V₂O₅/C has a higher stability than noble metal catalysts in the reaction medium. Supported by the Technology Research and Development Project for University of Shanxi Province of China (Grant No. 20051272)     

Hydrogen-bonding directed cocrystallization of flexible piperazine with hydroxybenzoic acid derivatives: Structural diversity and synthon prediction

Four hydroxybenzoic acid building blocks,m-hydroxybenzoic acid,2,4-dihydroxybenzoic acid,2,5-dihydroxyterephthalic acid,and 5-hydroxyisophthalic acid,have been synthesized as robust cocrystallizing agents and employed in reactions with piperazine,including [(C4H12N22+).(C7H5O3)2 ](1),[(C4H12N22+).(C 7H5O4)2 ](2),[(C4H12N22+).(C8H5O62)](3),and [(C4H12N22+)1/2.(C8H5O5)].2H2O(4).Hydrogen-bonded directed assemblies of four salts were validated by single-crystal X-ray diffraction analysis.In compounds 1-4,hydroxybenzoic acids are all deprotonated and piperazine molecules are all protonated to form piperazine dications and keep the chair conformation.Thermal stability of these compounds has been investigated.     

Synthesis and characterization of a new open-framework zinc phosphite (4,4′-(C5H4N)2(CH2)3)·[Zn3(HPO3)4]

Employing 4,4-trimethylenedipyridine as a template,a new two-dimensional zinc phosphite (4,4-(C5H4N)2(CH2)3)· [Zn3(HPO3)4 ] has been prepared at room temperature and characterized by single-crystal X-ray diffraction,FTIR,elemental analysis,powder X-ray diffraction,and thermogravimetric analysis.The compound crystallizes in the monoclinic space group P2 1 /c,with cell parameters,a=9.3309(19),b=14.798(3),c=33.637(7),β=91.11(3),V=4643.8(16) nm 3 and Z=4.The connectivity of the ZnO4 tetrahedra and HPO 3 pseudo pyramids results in infinite corner-sharing 4-membered ring chains as second building units which are further linked by Zn O P bonds to form a 2-D layer that with interesting 8-membered ring channels along the [100] direction.The diprotonated 4,4-trimethylenedipyridine molecules sit in the middle of the layers along the [100] direction and interact with the framework via hydrogen bonds.     

Strain effect on the orientation-dependent harmonic spectrum of monolayer aluminum nitride

In this study, we theoretically investigate the strain effect on the orientation-dependent high-order harmonic generation(HHG) of monolayer aluminum nitride(Al N) by solving the multiband semiconductor Bloch equations in strong laser fields. Our simulations denote that the efficiency of the orientation-dependent HHG is considerably enhanced when a 15% biaxial tensile strain is applied to Al N, which is attributed to the downshifting energy level of the conduction band. Furthermore, the odd-even feature in the orientation-dependent high harmonic spectra owing to the strain is considerably different when compared with that in the case without strain. The enhanced quantum interference between different energy bands in strained Al N around the Γ-M direction is responsible for the observed odd-even distributions of the orientation-dependent HHG. This study helps to better understand the HHG in solids by tuning their electronic structures.     

Cocrystallization of N-donor type compounds with 5-sulfosalicylic acid: The effect of hydrogen-bonding supramolecular architectures

Benzotriazole,N,N’-dimethylpiperazine and N-methylpiperazine were applied to crystallize with 5-sulfosalicylic acid(5-H2SSA),affording three new binary molecular cocrystals [(C6H6N3+).(C7H5O6S-)].H2O(1),[(C6H16N22+)1/2.(C7H5O6S-)].H2O(2) and [(C5H14N22+).(C7H5O6S-)2].3H2O(3) under general conditions.Proton-transferring occurs from acid to nitrogen of N-donor compounds in all compounds 1,2 and 3.Analysis of the hydrogen-bonding synthons and their effects on crystal packing were also presented in the context of crystal engineering and host-guest chemistry.In compound 1,1-D infinite chains are extended to a 2-D layered architecture via strong O-H...O hydrogen bonds and then to a 3-D network by N-H...O interactions.Compound 2 and 3 both have the 1-D chain which is formed by O-H...O bonds and weak C-H...O hydrogen bonds.A common intramolecular S(6) [synthon I] ring is formed by the hydroxyl with the carboxyl group in all three compounds.     

Sensitivity and regionally proximal relation in minimal systems

A topological dynamical system is n-sensitive,if there is a positive constant such that in each non-empty open subset there are n distinct points whose iterates will be apart from the constant at least for a same moment.The properties of n-sensitivity in minimal systems are investigated.It turns out that a minimal system is n-sensitive if and only if the n-th regionally proximal relation Q_n contains a point whose coordinates are pairwise distinct.Moreover,the structure of a minimal system which is n-sensitive but not(n 1)-sensitive(n≥2)is determined.     

Large eddy simulation of city micro-atmospheric environment

Air quality is one of the important conditions for a better residence life in the populated urban area and it is closed related to the micro-atmospheric environment. Atmospheric environment is controlled by air motion with multi-scales in the city, while air flows in the residence area are of micro-scale atmospheric motion. This paper introduces a modern numerical simulation method, i.e. large eddy simulation (LES), for studying micro-atmospheric flows in the city residence area. For the complex flow features in the residence area, the proper application of LES is studied and various numerical methods are compared in order to investigate their effects on the prediction accuracy of micro-atmospheric flows, for instance, roughness elements and immersed boundary method for complex terrain, different subgrid models and so on. The wind field (including turbulence properties) and contaminant dispersion are computed by the proposed method for a model and a realistic residence area, and the numerical results are in good agreement with the experimental measurements. Supported by the National Natural Science Foundation of China (Grant No. 10572073) and Foundation for Development of Science and Technology in Macao (Grant No. 022/2006/A)