Occurrence and congeners specific of poiychlorinated biphenyls in agricultural soils from Southern Jiangsu, China

A total of 198 agricultural soil samples were collected from Zhangjiagang and Changshu in Southern Jiangsu for analysis of 13 polychlorinated biphenyls （PCBs） in order to assess the levels of pollution, sources, area distribution, and potential risk for the environment. All methods were rigorously tested and an adequate quality control was ensured. Only one site had no PCBs residues, and the highest total PCBs concentration in the surface soils was 32.83 ng/g. The average concentration in all the soil samples was 4.13 ng/g, signaling low-level pollution. Tetra-, penta-, and hexa-chlorinated biphenyls were dominant species in soil samples, accounting for more than 75% of ∑PCBs in the soil samples. PCB118 was the most abundant congener in all the samples. The PCB118 was about 20% of ∑PCBs. The soil organic matter content showed only a weak correlation with the levels of all PCB congeners, in which a better correlation was noted for the more volatile lighter PCB congeners than for the heavier homologues. To a certain extent, the sources and land use seemed to influence the levels of PCBs.

Review on Service Curves of Typical Scheduling Algorithms

In recent years,various internet architectures,such as Integrated Services(IntServ),Differentiated Services(DiffServ),Time Sensitive Networking(TSN)and Deterministic Networking(DetNet),have been proposed to meet the quality-of-service(QoS)requirements of different network services.Concurrently,network calculus has found widespread application in network modeling and QoS analysis.Network calculus abstracts the details of how nodes or networks process data packets using the concept of service curves.This paper summarizes the service curves for typical scheduling algorithms,including Strict Priority(SP),Round Robin(RR),Cycling Queuing and Forwarding(CQF),Time Aware Shaper(TAS),Credit Based Shaper(CBS),and Asynchronous Traffic Shaper(ATS).It introduces the theory of network calculus and then provides an overview of various scheduling algorithms and their associated service curves.The delay bound analysis for different scheduling algorithms in specific scenarios is also conducted for more insights.

基于多层级特征筛选和无人机影像的冬小麦植株氮含量预测

氮素是冬小麦生长发育必不可少的大量元素,无人机超高分辨率影像丰富的光谱信息和纹理信息为冬小麦植株氮含量精准预测提供了重要的技术途径,但是过多变量造成了信息冗余和模型复杂的问题。针对此问题,该研究提出了一种“相关分析+共线性分析+LASSO(least absolute shrinkage and selection operator)特征筛选”的多层级植株氮含量敏感特征的筛选方法,引入约束系数向量的L1正则化实现特征的稀疏性,将某些特征的系数缩小为0,基于冬小麦关键生育期(拔节期、孕穗期、开花期、灌浆期)无人机影像提取的65个光谱和纹理特征,采BP神经网络(back propagation,BP)、Adaboost、随机森林(random forest,RF)和线性回归(linear regression,LR)4种机器学习算法构建了冬小麦植株氮含量预测模型。结果表明:相关分析筛选出51个通过0.01显著性检验的变量;基于共线性分析,当LASSSO正则化参数λ取值为0.08时,17个敏感特征变量被筛选。基于筛选的敏感特征变量,BP、Adaboost、RF和LR 4种算法建立的植株氮含量预测模型均达到了0.01水平差异显著性,且BP、Adaboost和RF 3种预测模型的精度具有高度的一致性,模型R2均为0.81,RMSE分别为0.36%、0.38%和0.37%,说明该研究提出的多层级特征筛选方法不仅使得模型变得简洁,而且稳健性高,可为智慧农业氮肥精准监测、智慧管理提供技术支撑。

Microtremor-based analysis of the dynamic response characteristics of earth-fissured sites in the Datong basin, China

This study conducted microtremor testing along six survey lines that cross three typical earth fissures in the Datong basin to determine the dynamic response characteristics of earth fissure sites with regard to the Fourier amplitude spectrum,response spectrum,and Arias intensity.The results show the following.(1)The predominant frequency of an earth fissure site is mainly affected by the thickness and the shear wave velocity of the soil layer and is minimally effected by the presence of an earth fissure.(2)Earth fissures have a pronounced amplification effect on dynamic response.Fourier amplitude,response acceleration,and Arias intensity are high near an earth fissure and decrease with an increase in distance from the earth fissure,tending toward stability at a distance of 20 m.(3)The area that is seriously affected by this amplification is within 6-8 m of an earth fissure,and the general affected area is farther out than this,to a distance of 25 m.(4)New construction should be avoided in an area affected by the amplification,and existing buildings in general and seriously affected areas need to be reinforced to increase their seismic fortification intensity.

基于样本嵌入的挖矿恶意软件检测方法

加密货币挖矿恶意软件的高盈利性和匿名性,对计算机用户造成了巨大威胁和损失。为了对抗挖矿恶意软件带来的威胁,基于软件静态特征的机器学习检测器通常选取单一类型的静态特征,或者通过集成学习来融合不同种类静态特征的检测结果,忽略了不同种类静态特征之间的内在联系,其检测率有待提升。文章从挖矿恶意软件的内在层级联系出发,自下而上提取样本的基本块、控制流程图和函数调用图作为静态特征,训练三层模型以将这些特征分别嵌入向量化,并逐渐汇集从底层到高层的特征,最终输入分类器实现对挖矿恶意软件的检测。为了模拟真实环境中的检测情形,先在一个小的实验数据集上训练模型,再在另一个更大的数据集上测试模型的性能。实验结果表明,三层嵌入模型在挖矿恶意软件检测上的性能领先于近年提出的机器学习模型,在召回率和准确率上相比其他模型分别提高了7%和3%以上。

Enzyme-Induced Carbonate Precipitation for the Protection of Earthen Dikes and Embankments Under Surface Runoff: Laboratory Investigations

Earthen structures such as shore protection dikes and river embankments easily suffer from erosion under surface water runoff.This study made experimental efforts to explore the enzyme-induced carbonate precipitation(EICP)method for slope erosion control under surface runoff for earthen structures.The sandy soils were treated by the EICP method for various rounds.Surface characteristics were evaluated by the surface penetration resistance,calcium carbonate content,and surface hard crust thickness of EICP-treated soils.Slope runoff erosion experiments were carried out to evaluate the erosion control performances of the EICP treatment.The surface penetration resistance,calcium carbonate content,and surface hard crust thickness were found to significantly increase with the treatment rounds.In the erosion experiments,it was observed that the level of damages decreased and the water flow volume required to trigger the damage increased with more treatments.The increase in the soil slope angle led to more serious surface damages.The amount and rate that the soil particles were eroded from the slope surfaces declined with more EICP treatments,which was consistent with those of visual observations.The preliminary investigations presented in this study have shown the potential of the EICP method for slope erosion control under surface runoff for earthen structures.

基于多源遥感数据的茶叶种植面积时空变化研究

茶叶是重要的经济树种之一,分析茶叶种植面积的时空演变规律可为优化河南茶叶布局提供科学依据。基于2000—2020年Landsat和Sentinel-2卫星数据,结合实地调查数据,采用随机森林分类方法获得河南省信阳市浉河区茶叶种植面积空间分布信息,采用趋势分析、重心迁移等方法对浉河区茶叶生产空间布局与时空变化趋势进行分析。结果表明:光谱+植被指数+纹理特征组合对茶叶分类精度最高,总体精度可达89.02%,Kappa系数为0.90;从时序变化来看,2000—2020年浉河区茶叶种植面积总体上呈现快速增长到稳步上升趋势。从空间变化来看,浉河区茶叶种植空间分布相对集中,主要分布于北部乡镇的丘陵地区和浅层山区。从重心变化来看,近20年浉河区茶叶种植面积重心呈现出由东向西转移的趋势,重心迁移总距离为5.47 km,迁移速度为0.2735km·a^(-1)。研究结果为茶叶科学种植提供了数据支撑。

近地面大长宽比跟踪式光伏阵列风洞试验研究

为明确近地面风场对跟踪式光伏结构风荷载取值的影响,本文基于风洞试验和计算流体力学(CFD)模拟对单排光伏组件的倾角、风向角、离地高度展开分析,并在此基础上研究了多排光伏阵列在不同风向角下,其遮挡效应对体型系数取值的影响.结果表明:单排光伏组件的表面风压符合梯形分布方式;多排光伏阵列中上游组件对下游的遮挡程度会随倾角的增大而增长,且后排光伏组件体型系数随着前排遮挡的增多逐渐趋于稳定;离地高度对光伏组件及阵列的体型系数存在一定的影响.

基于MTMD的管道振动倍频响应减振研究

大型化工管道受管内流体流动、边界约束、振源激励等复杂因素影响,服役期间往往会发生振动,其振动频率相较于土木结构较高,且可能存在多个主要频率成分.若采用单一频率的调谐质量阻尼器(Tuned Mass Damper,TMD),难以达到理想的控制效果,而采用多重调谐质量阻尼器(Multiple Tuned Mass Damper,MTMD)时,受现场条件限制,又存在无法确定最优安装位置等问题.本文开展了基于MTMD的管道倍频响应减振研究.首先,开展了某化工企业丙烷脱氢装置的大型管道现场实测研究,发现管道振动频率存在明显的倍数关系,即倍频现象.其次,建立局部管道有限元模型,分析管道动力特性,提出了基于数值搜索法的MTMD参数设计方法.最后,考虑化工管道现场安装条件的限制,研究了MTMD安装位置对管道减振效果的影响.数值研究结果表明,安装MTMD可有效减小管道振动响应.

生物酶辅助氧化镁碳化过程砂土加固试验研究

基于微生物或酶诱导碳酸盐沉积(即MICP和EICP)过程的固土技术具备固化强度高、环境友好等特点,但是目前也存在处理效率低、耗时长等局限。为克服这些局限,研究一种新型高效的生物固土技术,即基于植物脲酶辅助氧化镁碳化(酶辅助碳化)过程的固土法,探索其处理方法、效果和作用机理,并与单纯的氧化镁碳化、EICP和水泥等方法进行比较。结果表明,采用酶辅助碳化加固法时,一遍处理强度可达0.92 MPa,且试样的强度显著高于单纯氧化镁处理(0.30 MPa)、EICP处理(0.28 MPa)和水泥处理(0.69 MPa)。酶辅助碳化加固法处理试样的制备方式对强度影响较大。与注入法相比,采用拌和法处理的试样强度高了3倍。此外,添加少量脱脂奶粉后,酶辅助碳化加固法处理试样的强度进一步提升了约70%,达到1.30 MPa。通过微观结构和矿物成分分析发现,酶辅助碳化处理后,固化物填满了砂颗粒之间的孔隙,将砂颗粒结合在一起,形成稳定网格空间结构,与不添加脲酶的试样相比,其中的水合碳酸镁混合物含量较高,中间产物水镁石含量较低。

过渡性肥煤煤质分析与配煤试验研究

系统研究过渡性肥煤的煤质特性和结焦性能,以及其在炼焦配煤中的作用及适配性。试验结果表明:过渡性肥煤是一种介于肥煤和焦煤二者之间的过渡性煤种,既具有肥煤的强黏结性工艺性质,又具有焦煤的煤岩相结构,单种煤结焦性能好,其结焦性能处于肥煤和焦煤之间,单种煤所炼焦炭的冷、热态强度好,但略差于典型焦煤所炼焦炭的冷、热态强度。用15%的2^(#)T FM替代焦煤时,焦炭质量可满足大型高炉使用要求,并可在一定程度上降低焦炭灰分和硫分。通过配用一定比例的过渡性肥煤,可以提高焦炭质量,降低焦煤配用量,降低配煤成本,节约优质焦煤资源,扩大炼焦煤的使用范围。

基于绝对加速度观测量的地震动时程及结构参数识别研究

针对未知地震作用下框架结构的参数识别问题,提出了一种基于扩展卡尔曼滤波(extended Kalman filter,EKF)的地震动时程反演与结构参数识别方法。首先,将首层底板的层间边界力视作未知外激力,利用未知激力下的EKF算法识别此未知激励以及其余层的剪切刚度;其次,采用傅里叶变换,从绝对加速度时程中获取结构基频,进而根据特征方程识别首层刚度系数;最后,基于识别的结构参数,进一步修正未知边界力,并结合Newmark-β法反演地震加速度时程。文中通过5层框架模型数值算例和振动台试验验证了本文算法的有效性。

A Study on the Pros and Cons of China＇ s Financial Openness

In 2008,the U. S. subprime mortgage crisis triggered global financial crisis quickly and spread all over the w orld,w hich caused serious losses to many countries. T herefore,w hether china should insist on financial market opening have become a hot topic to debate. T his article discussed the advantages and disadvantages on C hinese financial market opening. It firstly review ed opening history of C hina's financial market,and then analyzed its current situation from three aspects including banking,securities industry and insurance industry.Finally,the paper introduced the benefits and problems of financial market opening to the outside w orld,and provided suggestions for the opening process.

枸杞病虫害综合防治技术

阐述了枸杞病虫害综合防治技术的研究成果。该防治技术以“监测预报、综合防治”为原则,明确了枸杞园主要病虫害监测关键期的调查方法及枸杞病虫害防治5个阶段的防治时期、防治对象、防治措施,以期为提高枸杞园病虫害的防治水平提供技术指导。

Assessment of community health needs of Chongqing residents: a qualitative study

Objective: The aim of this preliminary qualitative study was to gain insight into community health needs in order to develop health program for community in Chongqing. Methods: Totally 40 participants were assigned into 6 focus group discussions. All groups were led by local language speakers, and their talking was recorded after gaining informed consent. Transcribed data were coded and subjected to thematic analysis. Results: The main obtained themes were that community health problems were chronic noncommunicable disease, main health service needs included regularly free check-up and health education, and perceived health risk factors were unhealthy lifestyle and behavior as well as environment problems. Conclusion: Our community health needs assessment (CHNA) with FGDs indicate that residents realize the importance of prevention of disease. Our study identifies that primarily community health promotion is one of the priorities of community health service needs, including reorienting health service, health education, guiding behavior or lifestyle, and creating healthy environments. The findings of this study can provide guidance to the development of more effective and pertinent health program in this community.

长链非编码RNA NEAT1、miRNA-182-5p与2型糖尿病合并代谢性脂肪性肝病患者肝纤维化风险的相关性研究

背景随着慢性代谢性疾病的发病率逐年增加,已威胁全民健康,目前非编码RNA与内分泌代谢相关疾病的研究已成为国内外研究热点,其中长链非编码RNA核富集转录体(lncRNA NEAT1)及微小RNA(miRNA)-182-5p在2型糖尿病(T2DM)合并代谢相关脂肪性肝病(MAFLD)中的研究鲜有报道。目的探讨T2DM合并MAFLD患者lncRNA NEAT1、miRNA-182-5p在肝纤维化发生、发展中的机制及临床意义。方法纳入2021年10月—2022年6月在内蒙古科技大学包头医学院第一附属医院内分泌科就诊的T2DM患者236例为研究对象,同时纳入49名健康志愿者为健康对照组。收集研究对象一般资料与实验室检测结果。测定内脏脂肪面积(VFA)、皮下脂肪面积(SFA)。采集外周血,测定lncRNA NEAT1、miRNA-182-5p。将T2DM患者其分为T2DM合并非MAFLD组(n=82)与T2DM合并MAFLD组(n=154)。进一步根据肝纤维化指数(FIB-4)将T2DM合并MAFLD组分为肝纤维化低危亚组(n=55)、肝纤维化中危亚组(n=69)、肝纤维化高危亚组(n=30)。采用Spearman秩相关分析探究肝纤维化高危亚组lncRNA NEAT1、miRNA-182-5p表达水平的相关性,采用多因素有序Logistic回归分析探究T2DM合并MAFLD患者肝纤维化风险的影响因素。结果健康对照组年龄、颈围(NC)、空腹血糖(FPG)、糖化血红蛋白(HbA1c)低于T2DM合并MAFLD组、T2DM合并非MAFLD组,白蛋白(Alb)高于T2DM合并MAFLD组、T2DM合并非MAFLD组(P<0.05);T2DM合并MAFLD组BMI、腰围(WC)、VFA、SFA、稳态模型评估胰岛素抵抗指数(HOMA-IR)、三酰甘油(TG)、血尿酸(SUA)、lncRNA NEAT1高于健康对照组、T2DM合并非MAFLD组,血小板计数(PLT)低于健康对照组、T2DM合并非MAFLD组,总胆固醇(TC)低于健康对照组(P<0.05);T2DM合并非MAFLD组HOMA-IR、lncRNA NEAT1高于健康对照组,miRNA-182-5p高于健康对照组、T2DM合并MAFLD组,丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)低于健康对照组、T2DM合并MAFLD组(P<0.05)。肝纤维化低危亚组VFA、SFA、AST、lncRNA NEAT1低于肝纤维化中危亚组、肝纤维化高危亚组,PLT、miRNA-182-5p高于肝纤维化中危亚组、肝纤维化高危亚组,BMI、WC、NC低于肝纤维化高危亚组,TC高于肝纤维化高危亚组(P<0.05);肝纤维化中危亚组PLT、miRNA-182-5p高于肝纤维化高危亚组,AST、lncRNA NEAT1低于肝纤维化高危亚组(P<0.05)。Spearman秩相关分析结果显示,肝纤维化高危亚组患者lncRNA NEAT1与miRNA-182-5p呈负相关(r_(s)=-0.438,P<0.05)。多因素有序Logistic回归分析结果显示,lncRNA NEAT1(OR=1.326,95%CI=1.087~1.616)、VFA(OR=1.019,95%CI=1.006~1.033)、miRNA-182-5p(OR=0.083,95%CI=0.027~0.257)、PLT(OR=0.956,95%CI=0.942~0.970)、AST(OR=1.048,95%CI=1.022~1.075)是T2DM合并MAFLD患者肝纤维化风险的影响因素。结论外周血lncRNA NEAT1、miRNA-182-5p与T2DM合并MAFLD患者并发肝纤维化密切相关,为该病的早期预测及诊治提供依据。

Fault-caprock Dual Control Hydrocarbon Accumulation Regularity in Volcanic Rocks in Xujiaweizi Fault Depression

To recognize the gas forming rule of Xujiaweizi depression under the fault-cap rock dual control, this paper is base on the material of Xujiaweizi which includes three- dimensional seismic processing results interpretation of logging curves outcrop core observation and analytical test in laboratory, Analysis of the lithology, distribution and brittle ductile characteristics of ductile brittle of Xujiaweizi depression, evaluating sealing property of cap rock, studying deformation mechanism of the fracture in patch of cap rock, analyzing the top sealing ability and vertical adjustment of gas.

荒漠草原优势植物细根分解对土壤碳矿化与土壤养分的影响

【目的】研究宁夏东部荒漠草原优势植物细根分解对土壤碳矿化与土壤养分的影响,进一步分析优势植物细根分解动态与养分返还过程。【方法】以宁夏东部荒漠草原优势植物短花针茅(Stipa breviflora)与蒙古冰草(Agropyron mongolicum)细根为研究对象,设置对照(CK)、添加短花针茅细根(Sb)与添加蒙古冰草细根(Am)3种处理,采用室内培养法研究细根分解特征及其对土壤碳矿化与土壤养分的影响。【结果】连续培养61 d后,添加短花针茅和蒙古冰草细根显著增加土壤24 h CO_(2)释放总量、分解初期(前14 d)土壤碳矿化速率与累积CO_(2)释放量(P<0.01)。添加短花针茅与蒙古冰草细根使土壤激发效应显著增加(P<0.01),增幅为40.50%与35.28%。与CK相比,添加短花针茅和蒙古冰草细根显著增加土壤硝态氮含量(P<0.01),对土壤速效磷无显著影响。细根纤维素含量、m(C)∶m(N)与24 h CO_(2)释放总量呈显著负相关(P<0.05);细根碳含量、木质素含量、m(木质素):m(N)与24 h CO_(2)释放总量呈显著正相关(P<0.05)。细根木质素含量、m(木质素)∶m(N)与累积CO_(2)释放量呈显著正相关(P<0.05)。细根碳含量、氮含量、纤维素含量、m(N)∶m(P)与细根损失率呈显著正相关;细根木质素含量、m(木质素)∶m(N)与细根损失率呈显著负相关。【结论】植物细根初始化学性质是影响荒漠草原土壤有机碳矿化与养分循环的重要因素之一。

安徽省马鞍山市蜱携5种病原体的检测研究

目的了解安徽省马鞍山市蜱携5种重要病原体的感染情况,并分析其与我国既往检出病原体的亲缘关系。方法在马鞍山市周边13个村庄采蜱642只,采用形态学和线粒体COI基因鉴定蜱种。对于土拉弗朗西斯菌检测16S rRNA,巴尔通体检测ssrA,立克次体检测16S rRNA、ompA和ompB,无形体检测16S rRNA和gltA,柯克斯体检测groEL和rpoB。在公共数据平台选取有代表性的序列,与本研究测序获得的基因序列比对,采用MEGA11.0构建系统进化树。结果在640只长角血蜱中共有36只蜱检出立克次体,其中20只蜱中检出黑龙江立克次体,16只蜱中检出敬信立克次体,2只蜱中检出牛无形体,186只蜱中检出柯克斯体样内共生体。本研究检出的黑龙江立克次体HY2和安徽省B8菌株聚在一个分支,敬信立克次体QL3和山西、江苏的聚在一个分支,而牛无形体JX4和山西省的聚在一个分支。经分析,还有17只蜱存在合并感染。5种病原体在2只龟形花蜱中均没有检测到。结论本研究首次在安徽省长角血蜱中检出敬信立克次体。对于斑点热立克次体和牛无形体,建议当地卫生部门做好相应的防控措施。

新疆南疆地区农村人群基于不同指南定义的单纯舒张期高血压与心血管疾病的关联

目的探索新疆南疆地区农村人群中基于不同指南定义的单纯舒张期高血压(IDH)与心血管疾病(CVD)风险的关联。方法以新疆生产建设兵团第三师51团常住人口作为研究对象。根据2017年美国心脏病学会/美国心脏协会(ACC/AHA)高血压指南和2020年中国高血压指南对IDH的定义,分别纳入研究对象6834人和8960人。采用Log-rank检验比较不同指南定义的IDH患者和血压正常者CVD事件累积发病率的差异;使用Cox比例风险回归模型探索IDH与CVD风险的关联。结果ACC/AHA指南所定义的IDH患病率比中国指南定义者高5.4%。两种指南定义的IDH患者与血压正常者的CVD累积发病率差异均无统计学意义(ACC/AHA指南,χ2=0.07,P=0.80;中国指南,χ2=3.85,P=0.05);ACC/AHA指南定义的IDH患者CVD累积发病率较中国指南定义者低(6.14%vs 9.88%,χ2=5.22,P=0.02)。与血压正常者相比,中国指南定义的IDH与CVD发生风险的关联强度高于ACC/AHA指南,但差异无统计学意义,HR(95%CI)分别为:1.411(0.999~1.993)、1.037(0.788~1.364)。结论在新疆南疆农村人群中,应用2017年ACC/AHA指南定义的血压新阈值能够筛选出更多的IDH患者,有利于早期采取有效的防控措施。