Establishment of a Loop-mediated Isothermal Amplification Method for Rice Bacterial Leaf Brown Spot Disease

Rice bacterial leaf brown spot disease caused by Pseudomonas syringae pv.syringae(Pss)is a major disease on rice.In recent years,Pss has emerged worldwide,seriously affecting rice production.It is very important to establish a rapid detection method of Pss for the diagnosis and prevention of this disease.In order to robust and accurately diagnose the rice bacterial leaf brown spot disease in the field and laboratory,an assay system for the Pss was developed in this study,and the specific sequence of hrcN was used as the target,based on loop-mediated isothermal amplification(LAMP).The best detection system was MgSO 48 mmol·L^(-1),Bst DNA polymerase 8 U,dNTP 1.4 mmol·L^(-1),the ratio of internal and outer primers was 2:1,the reaction temperature was 63℃,the reaction time was 45 min,and the lowest sensitivity was 104 CFU·mL^(-1).This results provided an accurate and robust method for laboratory and field diagnosis of bacterial leaf brown spot disease of rice.

Rapid and Visualized Detection Method of Canine Parvovirus Using Loop-Mediated Isothermal Amplification

[Objective] To develop a rapid and visualized detection method using loop-mediated isothermal amplification （LAMP）, improve the detection rate of canine parvovirus （CPV） and reduce the testing cost. [ Method] According to the conserved regions of the VP2 gene of CPV, six primers were designed to amplify the special DNA sequences by LAMP. In addition, the reaction conditions of LAMP were optimized, and the sensitivity, specificity, repeatability and stability were verified. [ Result] The optimal reaction time of the LAMP method for CPVwas 60 min. The products obtained by LAMP had high specificity without cross-reaction with other generic viruses. The sensitivity of the LAMP was 100 times higher than that of PCR. [ Conclusion] The LAMP method for detecting CPV has high practical value. It has many advantages such as high specificity, high sensitivity, simple operation, low cost and rapid analysis, and it does not require special equipment. Therefore, this method is more suitable for the detection of CPV.

Preparation of Microcapsules Containing Aqueous Solution of Azur B with Melting Dispersion Cooling Method and Application to DNA Amplification Detector

Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting temperature of 75°C was used as the shell material. In the experiment, the aqueous solution (W) of Azur B as the core material was dispersed in the melted paraffin wax (O) to form the (W/O) emulsion and then, the (W/O) emulsion was dispersed in the silicon oil (O’) as the continuous phase to form the (W/O)/O’ emulsion at 85°C. After formation of the (W/O)/O’ emulsion, the microcapsules were prepared by cooling the (W/O)/O’ emulsion to 50°C. The microcapsules were prepared by changing the concentration of oil soluble surfactant in the (W/O) emulsion and the volume of the (W/O) emulsion in the (W/O)/O’ emulsion. The microencapsulation efficiency increased with the concentration of oil soluble surfactant and finally became 100% under the optimum conditions. Furthermore, the microcapsules were melted down at temperature of 85°C to reveal the sharp thermal responsibility and to release the aqueous solution of Azur B. As a result, it was found that the microcapsules were able to be applied to the amplification detector of plant DNA by utilizing the reaction between DNA and Azur B.

Auditory Hopf Amplification Revealed by an Energy Method

We report on the auditory Hopf amplification contributed by the electrical energy of the hair cell during its bundle deflecting. An energy method to calculate the active force is adopted according to the electrical energy consumption of the hair cell. After some experimental data was analyzed and simulated, we find that the electrical energy determines the value of the active force and enlarges the mechanical response of the hair bundle. This amplification is controlled by the cell voltage and makes the sensor a Hopf vibrator with hearing nonlinear characteristics. A velocity-dependent active force derived previously from the force-gating channel operation strongly reinforces our conclusion.

Rapid detection of Pseudomonas aeruginosa by cross priming amplification

Pseudomonas aeruginosa(PA)is an opportunistic pathogen of humans and animals and a common source of nosocomial infections especially of the respiratory tract.Pseudomonas aeruginosa is also a major bacterial disease of poultry and in particular,eggs and newly hatched chicks.In this study,we developed a simple,accurate and rapid molecular detection method using cross priming amplification(CPA)with a nucleic acid test strip to detect P.aeruginosa.The assay efficiently amplified the target gene within 45 min at 62℃only using a simple water bath.The detection limit of the method was 1.18x 102 copiesμL^-1 for plasmid DNA and 4.4 CFU mL^-1 for bacteria in pure culture,and was 100 times more sensitive than conventional PCR.We screened 83 clinical samples from yellow-feather broiler breeder chickens and hospitalized/treated dogs and cats using CPA,PCR and traditional culture methods.The positive sample ratios were 15.3%(13/83)by CPA,13.3%(11/83)by PCR and 12.1%(10/83)by the culture method.The established CPA method has significant advantages for detecting P.aeruginosa.The method is easy to use and possesses high specificity and sensitivity without the requirements of complicated experimental equipment.The PA-CPA assay is especially fit for outdoor and primary medical units and is an ideal system for the rapid detection and monitoring of P.aeruginosa.

Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅱ): with saturated poroelastic soil layers

As the continuation study on amplification of in-plane seismic ground motion by underground group cavities in layered half-space, this study extends to the case of poroelastic half-space with dry poroelastic and saturated poroelastic soil layers. The influence of poroelastic layers on the amplification of seismic ground motion is studied both in frequency domain and time domain using indirect boundary element method （IBEM）. It is shown that for the example of a saturated poroelastic site in Tianjin under the excitation of Taft wave and E1 Centro wave, the amplification of seismic ground motion in poroelastic case is slightly smaller than that in the elastic case, and the amplification of PGA （peak ground acceleration） and its PRS （peak response spectrum）.. can be increased up to 38.8% and 64.6%; the predominant period of response spectra in poroelastic case becomes shorter to some extent compared with that in the elastic case. It is suggested that the effect of underground group cavities in poroelastic half-space on design seismic ground motion should be considered.

Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅰ)

Amplification of in-plane seismic ground motion by underground group cavities in layered half-space is studied both in frequency domain and time domain by using indirect boundary element method （IBEM）, and the effect of cavity interval and spectrum of incident waves on the amplification are studied by numerical examples. It is shown that there may be large interaction between cavities, and group cavities with certain intervals may have significant amplification to seismic ground motion. The amplification of PGA （peak ground acceleration） and its PRS （peak response spectrum） can be increased up to 45.2% and 84.4%, for an example site in Tianjin, under the excitation of Taft wave and E1 Centro wave; and group cavities may also affect the spectra of the seismic ground motion. It is suggested that the effect of underground group cavities on design seismic ground motion should be considered.

Seismic ground amplification induced by box-shaped tunnels

The growing use of underground structures,specifically to facilitate urban transportation,highlights the need to scrutinize the effects of such spaces on the seismic ground response as well as the surrounding buildings.In this regard,the seismic ground amplification variations in the vicinity of single and twin box-shaped tunnels subjected to SV waves have been investigated by the finite difference method.To evaluate the effects,generalizable dimensionless diagrams based on the results of parametric numerical analysis considering factors such as variations in the tunnels′depth,the distances between the tunnels,tunnel lining flexibility,and input wave frequency,have been presented.In addition,to assess the effects of underground box-shaped tunnels on the response spectrum of the ground surface,seven selected accelerograms have been matched based on a specific design spectrum for the stiff soil condition of Eurocode 8(CEN,2006).The results underline the significant amplification effect of the box-shaped tunnels on the ground motions,specifically in the case of horizontal twin tunnels,which should be given more attention in current seismic design practices for surface structures.

放大电路静态在固定式偏置放大电路中的分析

论文主要从固定式偏置共射极放大电路静态工作点的分析方法出发,详细介绍了静态工作点分析常用的图解法和解析法,并对两种方法进行了对比,提出了两种方法的适用性和静态工作点选取的一般原则,为电子信息、电气自动化、机电工程、汽车、电力、城轨运营等专业的教学与学习提供了参考。

拟静力法在基坑抗震中的应用探讨

基坑工程作为项目建设的重要环节,其稳定性关系城市安全。随着地下枢纽、立体交通等理念的提出,部分基坑呈现规模大、周期长、周边环境复杂等特点。此时,不能简单将其视为一种临时结构,需要考虑地震等偶发灾害的影响。为了计算地震工况下的安全性,将拟静力法引入到基坑的稳定性分析中。汇总归纳了现有规范中的拟静力法,基于各规范的特点讨论了折减系数和放大系数取值原则。通过时程分析法,从剪力、弯矩和位移等方面进行验证。结果表明:在应用拟静力法时,应该考虑基坑工程的特点。区别于边坡工程,基坑工程加速度小于或接近地表设计地震。因此,加速度放大系数可取为1。折减系数取0.25时,拟静力法计算结果略大于时程分析法,可以达到包络设计的目的。

多脉冲加载下PBX装药的应力放大效应

针对弹体侵彻过程中装药常常受到多脉冲载荷作用的问题,提出了一种装药多脉冲加载装置,研究了多脉冲加载下装药的应力放大效应。基于集中质量法建立了多脉冲加载装置的等效弹簧模型,对产生应力放大的条件进行了探讨。结果表明,多脉冲载荷频率与装药固有频率匹配时系统发生共振,装药产生响应放大,放大倍数随结构间隙宽度的增加而降低。装药多脉冲加载下存在一个时间区间,撞击加载的发生时刻落在该区间内时系统可产生放大效果。对高聚物黏结炸药(polymer bonded explosive,PBX)模拟材料,实现了实验室条件下应力幅值百兆帕、脉冲间隔毫秒级、脉冲次数3次且幅值逐渐放大的多脉冲载荷加载。

面向油品参数快速计量的高精度傅里叶近红外光谱仪

针对油品现场检测中实时性和准确度的需要,研制了一种面向油品参数快速计量的高精度傅里叶近红外光谱仪。该光谱仪采用相干长度扩增方法,可快速定位有效信号;通过驱动采集控制系统对傅里叶近红外检测光路进行100 nm等间隔的干涉调制,最终由傅里叶逆变换解析出的吸收光谱分辨力可达3.25 cm^(-1)。用该光谱仪对汽油样品进行质量检测的结果表明:该光谱仪可在短时间内对汽油中5种物质含量进行快速计量,其最大体积误差不超过0.7%,可以满足油品参数现场计量的需求,对市场中成品油质量的监管具有重要意义。

环介导等温扩增技术及扩增产物分析方法的比较

环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)自开发以来,以其操作简便、灵敏度高、特异性好、扩增效率高等优点得到广泛地研究,在细菌、病毒、寄生虫、转基因成分等检测和鉴定中发挥重要作用,检测样品涵盖食品、环境、医疗、动植物检疫鉴定领域。LAMP技术最大的优点之一是扩增产物分析方法简便快速、不需要特殊的设备,特别适合在基层检验机构和现场检验推广应用。随着分析方法的研究,LAMP技术与相关技术偶联,使得产物分析方法灵敏度大大提高,检测速度更快、更方便。该文对LAMP相关技术及LAMP扩增产物检测分析方法的研究进行比较与分析,以期为LAMP方法的应用和开发提供建议和方向。

基于可解释随机森林的场地放大系数估算方法研究

场地放大系数(F_(pga))是反映地震动峰值在不同地区的差异,也是评估地震动影响范围的关键参数。F_(pga)的估算采用单一参数,靠经验选取,估算结果存在较强的主观性。为此,选取KiK-net台网40个台站的地震记录,基于随机森林算法提出一种综合多参数的F_(pga)估算方法,且可解释各参数对F_(pga)估算的影响。所提估算方法以震级、震中距、震源深度、震源距、覆盖层厚度h、场地周期T、等效剪切波速(V_(SE)、V_(S30)、V_(S20)、V_(S10))作为输入,F_(pga)为输出。结果表明:预测F_(pga)的相关系数为0.84,误差均值为0.01;震中距、震源深度、震源距对F_(pga)估算呈正相关,震级、h、T、V_(SE)、V_(S30)、V_(S20)、V_(S10)对F_(pga)估算呈负相关,其中T和h对模型的影响最大。该模型可有效预测场地放大效应。

两级堰塞坝连溃过程数值模拟及溃口流量演化特征研究

在强震作用下,高山峡谷区易发生滑坡堵江形成串联的梯级堰塞坝,其中一级一旦溃决易引发梯级连溃。本文基于三维雷诺平均Navier-Stokes方程、湍流重正化群模型,以及悬移质和推移质冲蚀方程,并考虑溃口边坡的失稳坍塌,采用有限体积法建立了梯级堰塞坝连溃过程数值模拟方法,用于模拟连溃过程中的水动力特征及梯级堰塞坝的溃口形态演化过程。选择典型的两级堰塞坝连溃概化模型试验作为数学模型验证案例,对比实测值和计算结果发现,上下游堰塞坝溃口洪水流量过程和溃口形态演化过程基本一致,上下游堰塞坝溃口峰值流量、区间洪水演进时间等关键参数的相对误差小于±5%;比较上下游堰塞坝溃口洪水流量过程发现,梯级堰塞坝发生连溃时,溃坝洪水存在级联放大效应。选择上下游堰塞坝距离、河道坡度和下游坝坝高等三个关键参数,研究连溃洪水的放大效应及其影响因素,参数敏感性分析结果表明:下游坝溃口峰值流量随两坝间距和下游坝坝高的减小而增大,随河道坡度的增长呈先增大后减小的趋势;上游坝溃决洪水演进至下游坝时可能产生涌浪翻越并冲蚀坝顶,导致坝顶高程降低,并对下游坝发生溃决的时间以及溃口峰值流量产生影响,因此涌浪对下游坝溃决过程的影响与涌浪翻越坝顶的水量以及坝料冲蚀特性相关。选择小岗剑上、下两级堰塞坝连溃案例,通过对比计算和实测的溃口流量以及溃口形态发现,关键溃坝参数的相对误差小于±10%,验证了模型在实际案例中应用的合理性,本文提出的数值模拟方法可为梯级堰塞坝连溃风险评估和应急处置提供重要技术支撑。

土质边坡地震加速度放大效应数值模拟研究

为探究地震作用下边坡沿高程方向的峰值加速度(PGA)放大效应规律,采用OpenSees有限元软件对均质土坡在不同地震动下的PGA放大效应进行数值模拟计算,研究了土层剪切波速(V_(s))、坡角(θ)和坡高(H)等因素对PGA放大系数的影响规律。通过Logistic函数曲线对各PGA平均放大曲线进行拟合并对拟合形态参数进行分析,最终构建了基于剪切波速、坡角和坡高的三因素η计算公式,并对该公式进行了验证。

深水导管架平台波浪动力响应及参数敏感性分析

考虑到300 m级导管架平台的自振周期与自升式平台极为接近,自升式平台的波浪动力响应分析方法在理论上可应用于深水导管架平台,但应用前需要进行参数敏感性分析,采用SACS软件建立300 m级导管架平台有限元模型,结合JONSWAP波浪谱、利用线性叠加法构造满足高斯性条件的随机波浪;基于时域分析法,进行在随机波浪载荷下的结构动力响应分析;采用Winterstein/Jensen方法计算平台基底剪力和倾覆力矩的最可能最大值,以及动力放大系数;对波浪瞬态变化、模拟步长和时长、随机种子等参数对动力放大系数进行敏感性分析,结果表明,动力放大系数对波浪瞬态变化较为敏感、对模拟步长和时长,以及随机种子极为敏感。采用Winterstein/Jensen方法进行深水导管架平台动力响应分析时,基于敏感性分析得出的参数可获得更合理、准确的动力放大系数。

喇叭状结构和抛物面结构对声压放大的仿真

在声波探测领域,放大声压具有重要意义。为了放大声压,设计喇叭状结构和抛物面结构模型,使用基于COMSOL Multiphysics软件的有限元分析法建立两种结构的声压放大模型。首先,计算两种结构对声压的增益倍数。仿真结果表明,喇叭状结构能够对声压实现最大20倍的放大,抛物面结构能够对声压实现最大30倍的放大。其次,研究不同结构的尺寸对声压的放大效果。结果表明,喇叭状结构尺寸与波长相当时的放大效果最显著,抛物面结构开口直径在几个特定数值处的放大效果最显著。最后,对声波造成的膜振动幅度进行仿真。结果表明,喇叭状结构使振膜振动幅度提高2.7~6倍,抛物面结构使振膜的振动幅度提高2~3.3倍。

带低屈服点钢耗能梁段高强钢框筒结构的结构影响系数和位移放大系数研究

在传统钢框筒结构的部分裙梁跨中处设置LYP225低屈服点钢耗能梁段,其余构件采用Q460高强度钢材,提出带低屈服点钢耗能梁段高强钢框筒结构(HSS-FTS-LSL)。在地震作用下耗能梁段发生剪切屈服耗散地震能量,梁、柱等构件由于采用高强钢从而保持弹性或部分进入塑性阶段。为了研究HSS-FTS-LSL的结构影响系数和位移放大系数,以楼层数、耗能梁段长度及布置方式为变量,按照我国规范设计了3组共8个HSS-FTS-LSL算例,并且考虑高阶振型的影响,采用分布侧向力调整法对各算例进行了Pushover分析,基于改进的能力谱法计算了8个算例的结构影响系数和位移放大系数,分析了结构层数、耗能梁段长度及布置方式对结构性能系数的影响并给出了建议取值。最后,根据提出的HSS-FTS-LSL抗震设计反应谱对其中一个结构算例进行重设计,并对重设计前后两个算例结构进行弹塑性分析,对比了二者的抗震性能以及用钢量,验证了本文提出的HSS-FTS-LSL结构影响系数建议值的合理性。

分缝护栏致空心板梁桥L型裂缝预应力控制方法研究

为提高护栏分缝桥梁的耐久性和承载力,以台金高速公路杨司高架桥预制空心板梁桥为背景,研究通过施加预应力控制因护栏分缝引起L型裂缝的有效性,并针对既有桥梁加固和新建桥梁设计提出通用的有效方法。采用Abaqus软件建立既有桥梁和新建桥梁的有限元模型,研究车道荷载作用产生的应力放大效应;分析预应力筋布置高度和长度对边梁梁底应力的影响及对既有桥梁护栏分缝导致的预应力损失;在此基础上,提出L型裂缝的预应力控制方法。结果表明:边梁应力放大系数随桥梁跨径和护栏高度的增加而增大,其取值范围为[1.42,2.14];预应力筋布置高度越低,边梁跨中梁底应力越大;预应力筋布置长度越短,既有桥梁梁底应力越大,对新建桥梁应力没有影响;分缝护栏对既有桥梁施加预应力产生损失,对新建桥梁不会产生预应力损失;在边梁跨中施加相应的预应力,可有效抵消跨中的应力集中效应,防止主梁跨中产生L型裂缝。