Study on the Bacterial Carrying Seeds as the Primary Infection Sources of Curvularia Leaf Spot in Maize

[Objective] The aim was to study the bacterial carrying seeds as the primary infection sourcs of Cunularia leaf spot of maize, and to provide the theo-retical basis for the control of the disease in production. [ Method] Through slide germination and seed tissue isolation method, the viabilities of seeds with internaland external bacterial carrying were detected ; the infection of bacterial carrying of seeds on the young seedling was detected indoors by sand culture method ; and the infection of bacterial carrying seeds on maize was detected using field cultivation method. [Result] The conidia of Gunularia and mycelia carried by maize seeds could survive through the winter. Intemal bacterial carrying of seed affected the germination of seeds, but external bacterial carrying did not affect the germination; internal and external bacterial carrying seeds could infect the radicle and gemmule of maize seedling. [Condusion] The conidia of Curvularia and mycelia carried by maize＇seeds could survive through the winter and infect the seedling, which would make the seedlings have weak growth.

Preliminary Research on Primary Energy Source of High Current Electron Beam Accelerator Based on Spiral Pulse Forming Line

In this paper,the primary energy source of high current electron beam accelerator based on spiral pulse forming line is investigated.It consists of the constant-current power supply,the high voltage pulse capacitor,the field distortion switch,and the protection system.The primary energy source can discharge to the primary winding of the transformer with high voltage pulses whose amplitude of voltage is 40kV,current is 80kA,pulse width is 8μs and repetition frequency is less than 5Hz.The primary energy source is applied to a high current electron beam accelerator, and is featured by its compactness,stability and reliability.

Persistent organic pollutants in global surface soils:Distributions and fractionations

The distribution and fractionation of persistent organic pollutants(POPs)in different matrices refer to how these pollutants are dispersed and separated within various environmental compartments.This is a significant study area as it helps us understand the transport efficiencies and long-range transport potentials of POPs to enter remote areas,particularly polar regions.This study provides a comprehensive review of the progress in understanding the distribution and fractionation of POPs.We focus on the contributions of four intermedia processes(dry and wet depositions for gaseous and particulate POPs)and determine their transfer between air and soil.These processes are controlled by their partitioning between gaseous and particulate phases in the atmosphere.The distribution patterns and fractionations can be categorized into primary and secondary types.Equations are developed to quantificationally study the primary and secondary distributions and fractionations of POPs.The analysis results suggest that the transfer of low molecular weight(LMW)POPs from air to soil is mainly through gas diffusion and particle deposition,whereas high molecular weight(HMW)POPs are mainly via particle deposition.HMW-POPs tend to be trapped near the source,whereas LMW-POPs are more prone to undergo long-range atmospheric transport.This crucial distinction elucidates the primary reason behind their temperatureindependent primary fractionation.However,the secondary distribution and fractionation can only be observed along a temperature gradient,such as latitudinal or altitudinal transects.An animation is produced by a one-dimensional transport model to simulate conceptively the transport of CB-28 and CB-180,revealing the similarities and differences between the primary and secondary distributions and fractionations.We suggest that the decreasing temperature trend along latitudes is not the major reason for POPs to be fractionated into the polar ecosystems,but drives the longer-term accumulation of POPs in cold climates or polar cold trapping.