荧光光谱法研究PNA-DNA的杂交和解链

本文建立了一种以阳离子型荧光染料藏红 T(ST)作为荧光试剂的荧光猝灭新方法 ,ST首次被用于PNA- DNA杂交和解链的检测。实验结果发现当 PNA- DNA杂交形成双链时 ,可以在一定程度上猝灭 ST的荧光 ,而当双螺旋解链时 ,对 ST荧光的猝灭程度减小 ,逐渐接近于 ST本身的荧光 ,根据荧光强度的变化研究了 PNA- DNA的杂交和解链过程。通过 UV光谱实验证实了这种荧光猝灭由它们之间的静电作用以及 ST插入到双螺旋内部引起     

A new wavelet-based reconstruction algorithm for twin image removal in digital in-line holography

Two original methods are proposed here for digital in-line hologram processing. Firstly, we propose an entropy-based method to retrieve the focus plane which is very useful for digital hologram reconstruction. Secondly, we introduce a new approach to remove the so-called twin images reconstructed by holograms. This is achieved owing to the Blind Source Separation (BSS) technique. The proposed method is made up of two steps: an Adaptive Quincunx Lifting Scheme (AQLS) and a statistical unmixing algorithm. The AQLS tool is based on wavelet packet transform, whose role is to maximize the sparseness of the input holograms. The unmixing algorithm uses the Independent Component Analysis (ICA) tool. Experimental results confirm the ability of convolutive blind source separation to discard the unwanted twin image from in-line digital holograms.     

Numerical study on the performance of a twin-raft wave energy dissipator in a stilling basin

In this paper, a raft-typed wave energy dissipator is proposed, and a mathematical model for the hydrodynamics of such a dissipator is presented, based on Reynolds-averaged Navier–Stokes equations. The model is validated by a comparison of the numerical results with the results of other investigators. The validated model is then utilized to examine the effect of wave height, wave frequency, damping coefficient, flow velocity on wave energy dissipation ratio and wave transmission coefficient for a hinged twin-raft wave energy dissipator. Our results reveal that the differences in behaviour exhibited by an inviscid fluid and a viscous fluid can be large and vary considerably, depending on the flow velocity.     

电沉积多晶CdTe薄膜结构的电镜研究

CdTe(能隙E_g=1.45 eV)是一种制作太阳电池的理想半导体村料。用阴极电沉积法制备多晶CdTe薄膜具有方法简单、周期短、材料费用低于单晶硅而接近非晶硅等优点,颇引人注目。但该技术发展较晚,因此对其成膜机理,各种因素对薄膜质地、内部结构和光电性能的影响尚缺乏足够了解。本文通过实验发现:采用双阳极、调节电沉积电流、改变电解液组成,可使CdTe薄膜表面平整、不易产生枝晶。如进一步在氩气或空气流中进行热处理,可使薄膜中CdTe晶粒增大到0.4～0.5μm,最大可达0.7～0.8μm,并使伴生的CdTe孪晶现象也更明显,这些对CdTe薄膜光电转换性能的提高是有利的。     

妊娠与微量元素食疗的关系探讨

应用原子吸收分光光度法测定了2300例健康孕妇及150例未受孕健康妇女发中锌、铜、铁、钙的含量。结果表明,妊娠妇女微量元素缺乏率为：铁63．54％、锌44．26％、钙29．17％。研究揭示,微量元素与妊娠有非常密切的关系,应通过食疗调整,使孕妇体内微量元素维持在正常水平,保证孕妇的身体健康和胎儿的正常生长发育。     

彩超联合人绒毛膜促性腺激素β诊断早期宫外孕的研究

本文探讨经阴道彩色多普勒超声、人绒毛膜促性腺激素β(β-hCG)在早期异位妊娠诊断中的价值。选取异位妊娠患者78例作为观察组,根据超声影像特征,其中环状征型、混合包块型和典型孕囊型分别为15例、24例和39例;选取正常妊娠者140例作为对照组。两组均行经阴道彩色多普勒超声检查,采用电化学发光法检查血清β-hCG水平。结果显示,与对照组比较,观察组子宫内膜厚度和血清β-hCG水平降低(P<0.05);环状征型、典型孕囊型和混合包块型患者血清β-hCG水平比较差异有统计学意义(P<0.05);血清β-hCG水平联合子宫内膜厚度预测异位妊娠的ROC曲线下面积为0.901(P<0.05)。经阴道彩色多普勒超声联合β-hCG在异位妊娠诊断中有较好的效果,同时异位妊娠患者β-hCG水平与彩超影像特征有一定关系。     

HILIC‐MS‐based shotgun metabolomic profiling of maternal urine at 9–23 weeks of gestation – establishing the baseline changes in the maternal metabolome

In this data‐rich age it is no longer necessary to methodically isolate, characterize and measure specific molecules. What is important is to identify which of the hundreds or thousands of resolved and measured ‘unknown’ molecules are potentially associated with the pathophysiology of interest. We have taken LC‐MS data from pregnancy urine and applied SIMCA P+ data analysis software in shotgun metabolomics to search the large amount of data for significant metabolite changes that occur in the transition from the first to early second trimester of pregnancy. Seventy‐two individual urine samples were examined spanning 9–23 weeks of gestation. Three‐hundred and eighty‐three ions were identified and variations were mapped between profiles of different gestational age and the significance quantified. In urine collected during pregnancy, the transition from first to early second trimester revealed a relatively steady pattern of metabolites except for four that showed a dramatic fall in abundance as pregnancy progressed from the first to second trimester. The pattern of changes in urinary metabolites identified by Zwitterionic Hydrophilic Liquid Interaction Chromatography (ZIC‐HILIC) coupled to mass spectrometry was evaluated and we established a baseline of changes from which a search for metabolomic markers associated with clinical pathologies of pregnancy can be made as a part of wider ultraomics study. Copyright © 2014 John Wiley & Sons, Ltd.     

Shotgun metabolomic profiles in maternal urine identify potential mass spectral markers of abnormal fetal biochemistry – dihydrouracil and progesterone in the metabolism of Down syndrome

In Down syndrome (DS) in particular, the precise cellular mechanisms linking genotype to phenotype is not straightforward despite a clear mapping of the genetic cause. Metabolomic profiling might be more revealing in understanding molecular–cellular mechanisms of inborn errors of metabolism/syndromes than genomics alone and also result in new prenatal screening approaches. The urinary metabolome of 122 maternal urine from women with and without an aneuploid pregnancy (predominantly Down syndrome) were compared by both zwitterionic hydrophilic interaction chromatography (ZIC‐HILIC) and reversed‐phase liquid chromatography (RPLC) coupled to hybrid ion trap time of flight mass spectral analysis. ZIC‐HILIC mass spectrometry resolved 10‐fold more unique molecular ions than RPLC mass spectrometry, of which molecules corresponding to ions of m/z 114.07 and m/z 314.20 showed maternal urinary level changes that significantly coincided with the presence of a DS fetus. The ion of m/z 314.20 was identified as progesterone and m/z 114.07 as dihydrouracil. A metabolomics profiling‐based maternal urinary screening test modelled from this separation data would detect approximately 87 and 60.87% (using HILIC‐MS and RPLC‐MS, respectively) of all DS pregnancies between 9 and 23 weeks of gestation with no false positives. Copyright © 2014 John Wiley & Sons, Ltd.     

不同孪晶界密度银纳米线拉伸形变行为的分子动力学模拟

采用分子动力学方法模拟了不同孪晶界密度银纳米线的拉伸形变行为,分析了孪晶界密度对多晶银纳米线屈服强度、弹性模量和塑性变形机理的影响.在弹性形变区域,孪晶界的存在对杨氏模量变化的作用不明显.在塑性形变阶段,首先从表面边缘开始产生位错成核,然后延伸并受阻于孪晶界.在进一步拉伸载荷作用下,孪晶界将作为位错源产生新的位错.模拟结果表明,银纳米线的强度与孪晶界和晶粒的尺寸有关.孪晶界密度较小(即晶粒的长径比大于1)时,此纳米线的屈服应力比单晶纳米线还要小,只有当孪晶界密度较大时(即晶粒的长径比小于1),孪晶界使得纳米线得到强化.综合分析了孪晶界和晶粒尺寸对银纳米线的影响,为构建高强度金属纳米线打下基础.最后讨论了温度和拉伸速度对孪晶纳米线屈服应力所产生的影响,随着温度的升高,孪晶纳米线与单晶纳米线的屈服应力差先升高后趋于稳定;当拉伸速度逐渐增大,孪晶纳米线与单晶纳米线的屈服应力差先稳定后增大.