An advanced meshless method for time fractional diffusion equation

Recently, because of the new developments in sustainable engineering and renewable energy, which are usually governed by a series of fractional partial differential equations (FPDEs), the numerical modelling and simulation for fractional calculus are attracting more and more attention from researchers. The current dominant numerical method for modeling FPDE is Finite Difference Method (FDM), which is based on a pre-defined grid leading to inherited issues or shortcomings including difficulty in simulation of problems with the complex problem domain and in using irregularly distributed nodes. Because of its distinguished advantages, the meshless method has good potential in simulation of FPDEs. This paper aims to develop an implicit meshless collocation technique for FPDE. The discrete system of FPDEs is obtained by using the meshless shape functions and the meshless collocation formulation. The stability and convergence of this meshless approach are investigated theoretically and numerically. The numerical examples with regular and irregular nodal distributions are used to validate and investigate accuracy and efficiency of the newly developed meshless formulation. It is concluded that the present meshless formulation is very effective for the modeling and simulation of fractional partial differential equations

Joint effect of lattice interaction and potential fluctuation in colossal magnetoresistive manganites

Taking into account both the Jahn-Teller lattice distortion and the on-site electronic potential fluctuations in the orbital-degenerated double-exchange model, in which both the core-spin and the lattice distortion are treated classically, we investigate theoretically the metal-insulator transition (MIT) in manganites by considering the electronic localization effect. An inverse matrix method is developed for calculation in which we use the inverse of the transfer matrix to obtain the localization length. We find that within reasonable range of parameters, both the lattice effect and the potential fluctuation are responsible to the occurrence of the MIT. The role of the orbital configuration is also discussed.Comment: 4 figure

Fluctuations and scaling of inverse participation ratios in random binary resonant composites

We study the statistics of local field distribution solved by the Green's-function formalism (GFF) [Y. Gu et al., Phys. Rev. B {\bf 59} 12847 (1999)] in the disordered binary resonant composites. For a percolating network, the inverse participation ratios (IPR) with $q=2$ are illustrated, as well as the typical local field distributions of localized and extended states. Numerical calculations indicate that for a definite fraction $p$ the distribution function of IPR $P_q$ has a scale invariant form. It is also shown the scaling behavior of the ensemble averaged $$ described by the fractal dimension $D_q$. To relate the eigenvectors correlations to resonance level statistics, the axial symmetry between $D_2$ and the spectral compressibility $\chi$ is obtained.Comment: 7 pages, 6 figures, accepted by Physical Review

Chemical dynamics of triacetylene formation and implications to the synthesis of polyynes in Titan's atmosphere

For the last four decades, the role of polyynes such as diacetylene (HCCCCH) and triacetylene (HCCCCCCH) in the chemical evolution of the atmosphere of Saturn's moon Titan has been a subject of vigorous research. These polyacetylenes are thought to serve as an UV radiation shield in planetary environments; thus, acting as prebiotic ozone, and are considered as important constituents of the visible haze layers on Titan. However, the underlying chemical processes that initiate the formation and control the growth of polyynes have been the least understood to date. Here, we present a combined experimental, theoretical, and modeling study on the synthesis of the polyyne triacetylene (HCCCCCCH) via the bimolecular gas phase reaction of the ethynyl radical (CCH) with diacetylene (HCCCCH). This elementary reaction is rapid, has no entrance barrier, and yields the triacetylene molecule via indirect scattering dynamics through complex formation in a single collision event. Photochemical models of Titan's atmosphere imply that triacetylene may serve as a building block to synthesize even more complex polyynes such as tetraacetylene (HCCCCCCCCH)

土著致病菌及其胞外物在生物防治斑马贝中的作用

摘要 无脊椎动物斑马贝(Dreissena polymorpha) 的生物污损造成了巨大的经济损失，而应用从斑马贝体内分离出的土著菌株及其体外代谢产物对它进行生物防治是一种经济效益显著且对环境友好的方法.本文主要报导从斑马贝体内分离的土著菌株中筛选出致病菌并研究该细菌及其代谢产物对它的控制作用.在三十多种土著菌株中，中间气单胞菌（ Aeromonas media），维罗纳气单胞菌（A. veronii），杀鲑气单胞菌杀鲑亚种（A. salmonicida subsp. salmonicida）和腐败希瓦氏菌（Shewanella putrefaciens）是幼体斑马贝的致命致病菌.当接种量为每只斑马贝107 个细菌时，接种中间气单胞菌、杀鲑气单胞菌杀鲑亚种和腐败希瓦氏菌的5 d 死亡率为100%，而维罗纳气单胞菌为65%.通过扫描电镜(SEM)发现，垂死的斑马贝肌肉组织被破坏并含有大量的细菌.4种细菌代谢产物的不同组分表现出对斑马贝不同的致死效果，在所研究的3种不同Mr组分中（Mr10×103），>10 ×103组分具有最高致死率.这些结果为控制贝类无脊椎动物的生物污损提供了新方法. 图4 参24 Abstract Biofouling agent zebra mussel (Dreissena polymorpha) has caused enormous economic losses. Application of biological control method using indigenous microorganisms isolated from zebra mussels or extracellular materials extracted from these bacteria is economically significant and environmentally favored. The objectives of this study were to screen virulent bacterial species from isolated indigenous microorganisms of zebra mussels and to elucidate the function of microbial products in controlling the zebra mussels infestation. Among more than 30 bacteria isolated from temperature stressed mussels, Aeromonas media, A. veronii, A. salmonicida subsp. salmonicida, and Shewanella putrefaciens were virulent pathogens to juvenile zebra mussels. Inoculation of A. media, A. salmonicida subsp. salmonicida and S. putrefaciens resulted in 100% mortality within 5 d at 107 cells per zebra mussel, and 65% for A. veroni. On the mussel tissue a dense microbial population was evident from the moribund mussels viewed with Scanning Electron Microscopy (SEM). Bacterial metabolites, fractionated and concentrated from stationaryphase cultural supernatants (cell free) of the four bacterial isolates, displayed varying degrees of antagonistic effects on zebra mussels. Among the three size fractions examined, Mr10×103, the most lethal fraction seems to be>10×103 for three of the four isolates tested. The results suggest that both selective indigenous microorganisms and their extracellular metabolites may provide novel strategies for control of biofouling invertebrates. Fig 4, Ref 24link_to_OA_fulltex