Analysis of Meteorological Condition for Infection of the Pathogen of Tobacco Brown Spot (Alternaria alternate)

[Objective] The paper was to understand the suitable meteorological indexes and key meteorological factors for infection and prevalence of tobacco brown spot. [ Method] Tobacco brown spot disease in five topical mountainous climatic areas of Guizhou Province was investigated, and the difference of biological characteristics of different strains was analyzed indoor. Different meteorological conditions （light, temperature and humidity） were simulated in artificial climate box by using the uniform design method, and the difference of infection ability of Alternaria alternate in different climate zones was analyzed in leaves in vitro by hanging drop method. [ Result] The infection rate of A. alternate in different climate zones of Guizhou Province showed certain difference. In low temperature and mid- die humidity （the humidity is 50% -60%, the temperature is 10 -20 ℃） conditions, the pathogen could infect tobacco leaves, various strains had certain difference, but the difference was small. [ Conclusion] The paper provided theoretical basis for prevalence prediction and control of tobacco brown spot.

THE GENERALIZED LOWER ORDER OF DIRICHLET SERIES

In this paper,we study the generalized lower order of entire functions defined by Dirichlet series.By constructing the Newton polygon based on Knopp-Kojima’s formula,we obtain a relation between the coefficients of the Dirichlet series and its generalized lower order.

Precursor compound enabled formation of aqueous-phase CdSe magic-size clusters at room temperature

The formation pathway of aqueous-phase colloidal semiconductor magic-size clusters(MSCs)remains unrevealed.In the present work,we demonstrate,for the first time,a precursor compound(PC)-enabled formation pathway of aqueous-phase CdSe MSCs exhibiting a sharp absorption peaking at about 420 nm(MSC-420).The CdSe MSC-420 is synthesized with CdCl2 and selenourea as the respective Cd and Se sources,and with 3-mercaptopropionic acid or L-cysteine as a ligand.Absorption featureless CdSe PCs form first in the aqueous reaction batches,which transform to MSC-420 in the presence of primary amines.The coordination between primary amine and Cd^(2+)on PCs may be responsible to the PC-to-MSC transformation.Upon increasing the reactant concentrations or decreasing the CdCl_(2)-ligand feed molar ratios,the Cd precursor self-assembles into large aggregates,which may encapsulate the resulting CdSe PCs and inhibit their transformation to MSC-420.The present study sheds essential light on the syntheses and formation mechanisms of nanocrystals.