键合胍盐低聚物的抗菌聚苯乙烯的制备及其抗菌活性

在Haake转矩流变仪中,将盐酸胍与己二胺的低聚物(PHMG)与末端带环氧基的遥爪型聚苯乙烯(PS)进行熔融反应,得到具有抗菌性能的聚苯乙烯(PS-PHMG)。红外(FT-IR)光谱证明胍盐低聚物是以化学键的形式键合到PS分子链上的。分别用扩散法和振荡瓶法测试了抗菌聚苯乙烯对大肠杆菌和金黄色葡萄球菌的抗菌性能。扩散法实验表明,经提纯后的PS-PHMG不存在胍盐低聚物的溶出,但对大肠杆菌和金黄色葡萄球菌均有明显的抑菌圈。振荡瓶法结果表明:当PS中w(PS-PHMG)=0.2%(即w(PHMG)=0.069%)时,与大肠杆菌接触30 mi m后,抑菌率达100%;当w(PS-PHMG)=0.1%(即w(PHMG)=0.035%)时,30 min内对金黄色葡萄球菌的抑菌率也能够达到100%,具有较好的抗菌速效性,杀灭细菌的时间小于30 min。     

振动台模型试验中地基土域的数值模拟

针对土－结构动力相互作用振动台模型试验中有限地基土域的模拟问题，本文分别采用有限元法和边界元法对地基土模型的侧向人工边界和底部人工边界的合理位置问题进行了计算分析。文中首先采用三维有限元方法，探讨了地基土侧向垂直人工边界不同位置对群桩基础和箱形基础地震反应的影响，提出了侧向人工边界合理位置的具体建议；然后利用层土动力Green函数建立边界元模型，通过对埋入式条形基础的动力反应分析，探讨了底部水平人工边界的合理位置，提出了相应的建议。     

Reduced aliasing artifacts using shaking projection k-space sampling trajectory

Radial imaging techniques, such as projection-reconstruction （PR）, are used in magnetic resonance imaging （MRI） for dynamic imaging, angiography, and short-T2 imaging. They are less sensitive to flow and motion artifacts, and support fast imaging with short echo times. However, aliasing and streaking artifacts are two main sources which degrade radial imaging quality. For a given fixed number of k-space projections, data distributions along radial and angular directions will influence the level of aliasing and streaking artifacts. Conventional radial k-space sampling trajectory introduces an aliasing artifact at the first principal ring of point spread function （PSF）. In this paper, a shaking projection （SP） k-space sampling trajectory was proposed to reduce aliasing artifacts in MR images. SP sampling trajectory shifts the projection alternately along the k-space center, which separates k-space data in the azimuthal direction. Simulations based on conventional and SP sampling trajectories were compared with the same number projections. A significant reduction of aliasing artifacts was observed using the SP sampling trajectory. These two trajectories were also compared with different sampling frequencies. ASP trajectory has the same aliasing character when using half sampling frequency （or half data） for reconstruction. SNR comparisons with different white noise levels show that these two trajectories have the same SNR character. In conclusion, the SP trajectory can reduce the aliasing artifact without decreasing SNR and also provide a way for undersampling recon- struction. Furthermore, this method can be applied to three-dimensional （3D） hybrid or spherical radial k-space sampling for a more efficient reduction of aliasing artifacts.     

Development of an efficient and low-cost protocol for the manual PNA synthesis by Fmoc chemistry

An efficient and low-cost protocol for the manual synthesis of Peptide Nucleic Acids is reported here. The protocol relies on coupling reactions carried out with 2.5 equiv of PNA monomers activated with HOBT/HBTU, in the presence of pyridine/NMM. The protocol has been tested on four PNA oligomers with a length ranging from 9 to 12 bases and a purine content up to 67%.     

高耸钢筋砼—钢框架组合结构整体模型抗震实验研究

本文对首都机场这一典型的高耸钢筋混凝土筒—钢框架组合结构缩尺模型进行了模拟地震振动台试验研究，分析了高耸塔台结构的地震反应和破坏特征，并对这种下部为砼筒体，上部为钢框架结构的锚固连接及钢框架结构层间位移控制进行了深入探讨，为提出这类钢—砼组合结构体系抗震计算模型和设计理论提供了实验依据．     

高拱坝地震损伤破坏的并行计算研究

高拱坝在强震中的损伤破坏对其抗震安全评价具有重要意义,但与之对应的大规模数值模拟需要高效、强大的计算能力的支持,传统的串行计算难以满足,大规模并行计算是解决这一问题的有效途径。利用宏观均质假定基础上考虑混凝土细观不均匀性的拱坝地震损伤破坏模型,在消息传递并行环境下,基于主从编程模式和区域分解法,采用Fortran语言编制了并行计算程序。该程序在4节点微机集群上运行,实现了对某在建拱坝地震损伤破坏过程的数值模拟,计算规模超过百万自由度,获得的破坏形态与模型动力破坏试验符合良好。该程序可再现拱坝的损伤破坏过程,在拱坝的抗震分析中有良好的应用前景。     

Development of liquid phase microextraction based on manual shaking and ultrasound-assisted emulsification method for analysis of organochlorine pesticides in aqueous samples

A novel method using sample preparation method, "ultrasound-assisted emulsification microextraction" (USAEME) with manual shaking, coupled with gas chromatography using and an electron capture detector (GC-ECD) was developed for the analysis of organochlorine pesticides (OCPs) in aqueous samples. The apparatus is simple and easy to operate. After manual shaking for 10s, ultrasound was used to accelerate emulsification of the organic solvent (1-decanol) in aqueous solution. Only 10 μL of the low-toxicity extraction solvent is used in this method; no dispersive solvent is required and the total extraction time is ～4 min. Manual shaking before ultrasound-assisted emulsification enhances the extraction efficiency by >100%. The effects of horizontal and vertical orientation as well as the location of the sample within the ultrasonic bath were studied. After centrifugation, we used an improved solvent collection system (ISCS) to reduce the amount of extraction solvent required. A 1 μL sample of the extract was injected into the GC column. Under optimum conditions, the linear range of the method is 5-2500 ngL(-1) for most of the OCPs, and the limit of detection of the method ranged from 0.6 to 2.9 ngL(-1).The relative recoveries ranged from 75 to 107% for sea water and from 70 to 99% for field fresh water. The method, which provides good enrichment factors, low LODs and minimization of the consumption of organic solvent, provides a rapid, simple and environment-friendly procedure for determining OCPs in aqueous samples.     

基于梯度型最小二乘滤波的船摇隔离度测试研究

针对传统船摇隔离度测试方法效率低、误差大、操作复杂、且不能有效解决扰动跳变的不足,对船摇隔离的基本原理进行了分析,建立了梯度型最小二乘滤波模型,提出了基于梯度型最小二乘滤波和VC++语言编程实现船摇隔离度的自动测试方法,并利用跟踪实测数据进行了仿真实验。对比传统方法测试结果表明,该方法能有效滤除测量数据中的随机误差,较大程度地降低了扰动跳变的抖动量,提高了伺服系统船摇隔离度的测试精度。     

铅芯橡胶耗能器与油阻尼器组合耗能系统的振动台试验与分析

在一座三层单跨的钢结构模型中安装了铅芯橡胶耗能器及其和油阻尼器并联组合。对这两种耗能体系进行了振动台试验,以研究组合耗能体系的动力特性,检验其减振效果,试验结果表明：组合耗能体系对位移和加速度有良好的减振效果;在合适的刚度范围内,增加适当的阻尼可提高耗能器的减振效果,进行了数值分析,并与试验结果进行了比较,验证了本文提出的计算模型与方法的正确性。     

基于机器视觉技术的振动台试验变形位移测量方法研究

在振动台试验中,结构的变形位移是试验关注的重要数据之一。将机器视觉技术运用于振动台试验的变形位移测量上,是对传感器测量法的一个补充,从另外一种渠道力争为振动台试验提供更多的数据来源。该方法首先给定振动台一个激励信号,同时对固定在振动台台面上、粘贴有人工标志的弹性结构试件进行视频采集;然后将视频分帧成一系列静态图片,对静态图片进行图像灰度化、图像增强等图像预处理并对人工标志进行识别;接下来,在识别出所有人工标志的基础上采用最小二乘椭圆拟合法进行目标定位并进行像素标定。目标点的像素位移结合像素标定系数,最终完成变形位移的测量。最后通过振动台的固定位移试验和正弦信号激励试验证明了该方法在振动台试验中的可行性。