Evaluation of maize inbred lines currently used in Chinese breeding programs for resistance to six foliar diseases

Foliar diseases are common in most maize-producing regions and have caused serious yield reduction in China. To evaluate genetic resistance of parental lines actively used in maize breeding programs to major foliar diseases, 152 maize inbred lines were tested against northern corn leaf blight(NCLB), southern corn leaf blight(SCLB), Curvularia leaf spot(CLS),gray leaf spot(GLS), common rust, and southern rust from 2003 to 2005. A small number of lines exhibited highly resistant reactions to common rust and southern rust, but none were highly resistant to NCLB, SCLB, CLS, and GLS. Although 53.3%, 40.8%, and 80.7% of lines were resistant to NCLB, SCLB, and common rust, the resistance in most lines was moderate.Resistance to CLS, GLS, and southern rust was rare in this collection of maize lines. Five lines,313, Chang 7-2, Qi 319, Qi 318, and Shen 137, were resistant to five diseases tested. Lines belonging to heterotic subgroup PB exhibited better resistance to the foliar diseases than lines from other heterotic subgroups, such as BSSS, PA, Lancaster, LRC, and PA. The results will be of benefit to breeders for selecting lines in disease resistance breeding programs.

Improved STAP algorithm based on APES

Space-time adaptive processing（STAP） has been proven to be one of the best techniques capable of detecting weak moving targets in strong clutter environment and has been widely applied in airborne ground moving target indication（GMTI） radar.This paper applies an amplitude and phase estimation（APES） approach to two aspects of the STAP algorithm.Firstly,APES is applied to accurately describe the clutter characteristic in angle-Doppler domain.Then,APES is incorporated into the standard STAP algorithm to improve its performance without increasing transmitting/receiving channel and pulse number.The experimental examples show that the detection performance can be improved by using the APES technique,as well as the high computational complexity can be avoided.

Effect of catalyst diesel particulate filter aging and catalyst loadings on particulate emission characteristics from a diesel vehicle

In this study,the effect of new and used catalyzed diesel particulate filter(CDPF)with different catalyst loadings on the particulate emissions including the particle mass(PM),particle number(PN),particle size distribution(PSD)and geometric mean diameter(GMD)from a diesel vehicle were investigated based on a heavy chassis dynamometer.Results showed that more than 97.9%of the PN and 95.4%of the PM were reduced by the CDPF,and the reduction efficiency was enhanced by the catalyst loading.After using the CDPF,the PSD transformed from bimodal to trimodal with the peak shifting towards smaller particle size,more nucleation mode particles were reduced compared with accumulation mode ones,but the reduction effect on the accumulation mode particles was more significantly influenced by the catalyst loading.Notably,the CDPF increased the accumulation mode particles proportion,producing a larger GMD.For the used CDPF,its reduction effect on the particulate emissions enhanced,especially for the PM in accumulation mode.The PSD returned to bimodal,but the peak at accumulation mode began to be higher than that at nucleation mode,illustrating that more nucleation mode particles was removed.The aging of the CDPF resulted in greater effect on the PN-based PSD than that of PM-based PSD,but the effect of catalyst loading on the PN and PM emission factors was weakened.The used CDPF further increased the GMD,and the effect of catalyst loading on the GMD was strengthened,a higher catalyst loading led to a reduction in the GMD.

Spatiotemporal characteristics and Monte Carlo simulationbased human health risk of heavy metals in soils from a typical coal-mining city in eastern China

Mining activities typically discharge considerable amounts of heavy metals into the environment,raising concerns about soil metal pollution,environmental security,and human well-being.Therefore,a systematic regional-scale investigation of soil heavy metal pollution in mining areas is necessary for soil management.In this study,5817 soil samples from the Huainan coal mining area collected for studies conducted from 2000 to 2021 were compiled to quantify the pollution level and spatiotemporal variation of heavy metals(Cu,Pb,Zn,Cr,Cd,As,Hg,Ni,and Mn).The associated ecological health risk of heavy metals in soil was assessed using the Hakanson ecological hazard index,Monte Carlo simulation in conjunction with the total hazard quotient,and the hazard index.Cd was the top contaminant,followed by Hg.In terms of spatial distribution,heavy metal contamination was more severe in the eastern area of Fengtai and Datong districts,because these districts of Anhui Province are significant industrial regions.In addition,the results of the Monte Carlo evaluation of human health risks showed that the total noncarcinogenic risk of heavy metals in soil is below the acceptable level,while the carcinogenic risk was 5.97%for adults and 15.53%for children.As accounted for 57.4%of noncarcinogenic risk,Cr contributed 36.1%of carcinogenic risk.Compared with adults,children are more vulnerable to the carcinogenic and noncarcinogenic risks posed by heavy metals,with oral consumption being the primary exposure route.This research can provide useful details for protecting the environment and managing soil in a coal mining area.

Effect of catalyzed diesel particulate filter and its catalyst loading on emission characteristics of a non-road diesel engine

In this study, the effects of a diesel oxidation catalyst(DOC) coupled with a catalyzed diesel particulate filter(CDPF) with different catalyst loadings on the power, fuel consumption,gaseous and particulate emissions from a non-road diesel engine were investigated. Results showed that the after-treatment had a negligible effect on the power and fuel consumption.The reduction effect of the DOC on the CO and hydrocarbon(HC) increased with the engine load. Further reductions occurred coupling with the CDPF. Increasing the catalyst loading resulted in a more significant reduction in the HC emissions than CO emissions. The DOC could increase the NO_(2)proportion to 37.9%, and more NO_(2)was produced when coupled with the CDPF below 250℃;above 250℃, more NO_(2)was consumed. The after-treatment could reduce more than 99% of the particle number(PN) and 98% of the particle mass(PM).Further reductions in the PN and PM occurred with a higher CDPF catalyst loading. The DOC had a better reduction effect on the nucleation particles than the accumulation ones, but the trend reversed with the CDPF. The DOC shifted the particle size distribution(PSD) to larger particles with an accumulation particle proportion increasing from 13% to 20%, and the geometric mean diameter(GMD) increased from 18.2 to 26.0 nm. The trend reversed with the CDPF and the accumulation particle proportion declined to less than 10%. A lower catalyst loading on the CDPF led to a higher proportion of nucleation particles and a smaller GMD.

Chemically revised conducting polymers with inflammation resistance for intimate bioelectronic electrocoupling

Conducting polymers offer attractive mixed ionic-electronic conductivity,tunable interfacial barrier with metal,tissue matchable softness,and versatile chemical functionalization,making them robust to bridge the gap between brain tissue and electronic circuits.This review focuses on chemically revised conducting polymers,combined with their superior and controllable electrochemical performance,to fabricate long-term bioelectronic implants,addressing chronic immune responses,weak neuron attraction,and long-term electrocommunication instability challenges.Moreover,the promising progress of zwitterionic conducting polymers in bioelectronic implants(≥4 weeks stable implantation)is highlighted,followed by a comment on their current evolution toward selective neural coupling and reimplantable function.Finally,a critical forward look at the future of zwitterionic conducting polymers for in vivo bioelectronic devices is provided.

天宫二号成像高度计海洋内波特征及振幅反演

海洋内波是一种重要的中尺度海洋现象,星载合成孔径雷达(SAR)是其常用的观测手段之一。2016年发射的天宫二号干涉成像高度计(TG2-InIRA)第一次以1°~8°小入射对海洋进行干涉成像观测,以实现宽刈幅海面高度测量,目前尚无针对该入射角范围的内波成像模型开展研究的报道。基于TG2-InIRA图像建立了小入射角海洋内波一维成像模型,利用该模型对海洋内波成像特征进行了仿真分析,并采用变分模态分解(VMD)方法对内波参数进行反演。为验证模型及反演方法的正确性,利用TG2-InIRA和Sentinel-1 SAR间隔4 h 13 min对同一内波获取的雷达图像进行了亮暗条纹对比和内波参数反演实验。实验结果表明:TG2-InIRA海洋内波条纹的亮暗顺序与Sentinel-1 SAR的相反,所得到内波特征宽度和振幅的反演结果相对偏差分别为8.14%和15.62%,并且均表现出沿传播方向宽度由小到大、振幅由大到小的变化,符合内波传播的规律,从而展示了TG2-InIRA对内波的探测能力。对TG2-InIRA和Sentinel-1在南海区域分别获取的40幅和19幅内波图像的统计分析表明,大于80%的实际图像中内波条纹亮暗顺序与SAR相反,与所建立的模型和仿真结果一致。

基于FrFT与Kalman滤波的机动目标序列ISAR成像算法

序列逆合成孔径雷达(Inverse Synthetic Aperture Radar,ISAR)指雷达对目标在较长一段时间内连续观测,近实时生成目标的ISAR图像序列。通过这些图像序列能够充分提取目标的散射信息和运动状态变化信息,对目标监测、跟踪和识别有很大帮助。研究充分利用相邻帧间目标运动的连续性,联合分数阶傅里叶变换(Fractional Fourier Transform,FrFT)和卡尔曼(Kalman)滤波技术,提出一种新的机动目标序列ISAR成像算法。该算法对方位向信号进行FrFT,通过搜索FrFT最佳能量聚集对应旋转角实现对方位向信号调频率(Azimuthal Chirp Rate,ACR)的测量,然后使用Kalman滤波技术得到ACR的最优估计值,实现对方位向信号精确的相位补偿。基于当前帧Kalman滤波得到的ACR最优估计值可以减小下一帧FrFT旋转角的搜索范围,提高计算效率。通过实测数据验证了该算法的有效性。相比常用的FrFT参数估计算法和PGA算法,该算法在成像质量和计算效率上均展现了优势。

海南自由贸易港税收政策:框架解析和未来展望

本文系统梳理海南自由贸易港税收政策框架体系,并与世界较高水平自由贸易港、内地部分开放区域进行比较,对未来税收政策改革方向和制度细化提出若干建议。

First results on ^(76)Ge neutrinoless double beta decay from CDEX-1 experiment

We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.

Wolbachia enhances expression of NICYP4CE1 in Nilaparvata lugens in response to imidacloprid stress

The brown planthopper,Nilaparvata lugens,is one of the main insect pests of rice.The N.lugens gene NICYP4CE1 encodes cytochrome P450 monooxygenase(P450),which is a key enzyme in the metabolism of the insecticide imidacloprid.Previous research has suggested that the expression of NICYP4CEI is induced by imidacloprid stress,but the effect of bacterial symbionts on its expression has not been determined.The results of this study show that exposure to subtoxic imidacloprid changed the structure of the bacterial symbiont community in N.lugens.Specifically,the total bacterial content increased but the bacterial species diversity significantly decreased.Wolbachia accounted for the largest proportion of bacteria in N.lugens;its abundance significantly increased after subtoxic imidacloprid exposure.The transcript level of NICYP4CEI was significantly increased by imidacloprid,but this effect was significantly weakened after Wolbachia was cleared with tetracycline.This result suggests that Wolbachia enhances the expression of N1CYP4CE1 to promote the detoxification metabolic response to imidacloprid stress.Understanding the effect of bacterial symbionts on gene expression in the host provides a new perspective on interactions between insecticides and their target insect pests,and highlights that subtoxic imidacloprid exposure may raise the risk of insecticide resistance by altering the structure of bacterial symbiont communities.

Emission reduction characteristics of a catalyzed continuously regenerating trap after-treatment system and its durability performance

The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap(CCRT)system composed of a diesel oxidation catalyst(DOC)and a catalyzed diesel particulate filter(CDPF)on the main gaseous and particulate emissions from an urban diesel bus,as well as the durability performance of the CCRT system.Experiments were conducted based on a heavy chassis dynamometer,and a laboratory activity test as well as X-ray photoelectron spectroscopy(XPS)test were applied to evaluate the changes of the aged CCRT catalyst.Results showed that the CCRT could reduce the CO by 71.5%and the total hydrocarbons(THC)by 88.9%,and meanwhile promote the oxidation of NO.However,the conversion rates for CO and THC dropped to 25.1%and 55.1%,respectively,after the CCRT was used for one year(~60,000 km),and the NO oxidation was also weakened.For particulate emissions,the CCRT could reduce 97.4%of the particle mass(PM)and almost 100%of the particle number(PN).The aging of the CCRT resulted in a reduced PM trapping efficiency but had no observable effect on the PN;however,it increased the proportion of nucleation mode particles.The activity test results indicated that the deterioration of the CCRT was directly relevant to the increase in the light-off temperatures of the catalyst for CO,C3H8 and NO2.In addition,the decreased concentrations of the active components Pt2+ and Pt4+ in the catalyst are also important factors in the CCRT deterioration.

Performances of a prototype point-contact germanium detector immersed in liquid nitrogen for light dark matter search

The CDEX-10 experiment searches for light weakly interacting massive particles, a form of dark matter, at the China Jinping Underground Laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher rise-time resolution of the CDEX-10 prototype detector as compared with CDEX-1 B, we identified the origin of an observed category of extremely fast events. For data analysis of the CDEX-10 prototype detector, we introduced and applied an improved bulk/surface event discrimination method. The results of the new method were compared to those of the CDEX-1 B spectrum. Both sets of results showed good consistency in the 0-12 ke Vee energy range, except for the 8.0 keV K-shell X-ray peak from the external copper.