Noninvasive prenatal paternity testing by maternal plasma DNA sequencing in twin pregnancies

SNPs, combined with massively parallel sequencing technology, have proven applicability in noninvasive prenatal paternity testing (NIPPT) for singleton pregnancies in our previous research, using circulating cell-free DNA in maternal plasma. However, the feasibility of NIPPT in twin pregnancies has remained uncertain. As a pilot study, we developed a practical method to noninvasively determine the paternity of twin pregnancies by maternal plasma DNA sequencing based on a massively parallel sequencing platform. Blood samples were collected from 15 pregnant women (twin pregnancies at 9–18 weeks of gestation). Parental DNA and maternal plasma cell-free DNA were analyzed with custom-designed probes covering 5226 polymorphic SNP loci. A mathematical model for data interpretation was established, including the zygosity determination and paternity index calculations. Each plasma sample was independently tested against the alleged father and 90 unrelated males. As a result, the zygosity in each twin case was correctly determined, prior to paternity analysis. Further, the correct biological father was successfully identified, and the paternity of all 90 unrelated males was excluded in each case. Our study demonstrates that NIPPT can be performed for twin pregnancies. This finding may contribute to development in NIPPT and diagnosis of certain genetic diseases.     

Anisotropic compressive behavior of rigid PVC foam at strain rates up to 200 s−1

The elevated strain rate compressive response of closed-cell polyvinyl chloride (PVC) foam at various densities is investigated. Two loading directions, (i.e., parallel and perpendicular to foam rise direction) were considered to investigate structural anisotropy. The elevated strain rates tests (up to 200 s⁻¹) were performed using a customized drop tower device. Engineering stress/strain behavior, energy dissipation, and maximum stress capacity were obtained for each density and compared against each other. Except for the lowest density of 45 kg/m³, strain rate effects were clearly observed through increased compressive strength and plateau stress when loading in the foam rise direction. The strain rate effect is more evident at higher densities. However, no significant strain rate effect was observed when loading perpendicular to the foam rise direction. Scanning electron microscopy (SEM) analysis showed that plastic hinges are the primary deformation mechanism for PVC foam cells. An analytical model has been calibrated using the experimental results and successfully predicted the mechanical response of the foam. Shape anisotropy has been measured employing the SEM images. The analytical approach was also able to predict the foam's anisotropic mechanical response.     

Recent advances in the development of colorimetric analysis and testing based on aggregation-induced nanozymes

Colorimetric sensing strategies as a powerful point-of-care testing(POCT) tool have attracted significant interest in various chem/biosensing applications.Taking the excellent bare-eye-detectable signaling feature,nanozymes-based colorimetric sensors enable more potential applications and have been a new forefront in the colorimetric POCT analysis toward different target analytes.However,the low catalytic activity of nanozymes in most cases limits their practical application.Recent efforts demonstrate that the aggregation-induced nanozymes provide a general means to modulate nanozymes activity and enhance colorimetric sensing performances of some nanozymes-based colorimetric sensors.But there are few reports are explored to discuss and review such aggregation-induced nanozymes and their colorimetric sensing applications.To highlight the advances and progress in aggregation-induced nanozymes based colorimetric assays,we herein summary the fundamentals,classify and applications of this newlydeveloping field,focusing on the aggregation-induced activity enhancement of nanozymes(AIAEnanozymes) with a significant "signal-on" feature and aggregation-induced activity inhibition of nanozymes(AIAI-nanozymes) with a dramatical "signal-of" characteristics.Finally,we also propose the current challenges and the future prospects on both AIAE-nanozymes and AIAI-nanozymes.     

La0.7Ca0.3Mn1-xCrxO3的激光超声研究

运用激光超声的方法测定了五种不同掺杂的巨磁锰氧化物La0.7Ca0.3Mn1-xCrxO3(0.01≤x≤0.60)室温(300 K)下的超声纵波声速.结合热导率的数据,对声速随掺杂浓度的变化原因进行了深入的分析.得到在顺磁绝缘态Cr3 离子的掺入造成了晶格局部涨落的变化,低掺杂使得晶格局部涨落增强,声子U散射弛豫时间减小.     

近红外快速水份检测技术的应用

近红外检测技术是目前发展最快和最具有前景的分析技术之一,简要介绍了近红外检测技术的发展、优点和原理.利用该技术设计了豆类产品的水份检测仪器.并对近红外技术在水果、蔬菜、奶制品、制药和化工等方面的应用前景做了展望.     

锂离子电池硅氧化物负极首次库伦效率的影响因素与提升策略

硅氧化物(SiO_x, 0<x≤2)具有高的比容量和低的嵌锂电位, 且体积膨胀率显著低于纯硅负极, 因而被认为是替代传统石墨负极材料的理想选择之一. 然而SiO_x负极在首次嵌锂过程中表面形成的固体电解质界面膜(SEI)以及大量的不可逆产物, 造成其首次库伦效率偏低, 严重阻碍了SiO_x负极的实际应用. 本文从SiO_x的结构模型出发, 系统阐述了SiO_x负极的嵌锂机理以及首次库伦效率低的原因; 归纳了SiO_x负极首次库伦效率的提升策略及其研究进展; 并对提升SiO_x负极首次库伦效率的未来发展方向进行了展望.     

6S现场管理方法在计量检测实验室中的应用

6S现场管理的方法已经在多个领域得以运用并取得较好的效果。结合计量检测实验室的特点,从整理、整顿、清扫、清洁、素养、安全6各方面讨论了6S现场管理在计量检测实验室中的应用。该管理模式可以提高工作效率,降低物品遗失率,减少寻找物品的时间等,提高计量检测质量。     

通过确定初始电离位点预测吲哚类生物碱质谱的特征裂解规律

确定初始电离位点是EI源质谱解析中一个至关重要的环节. 本文提出了一种确定初始电离位点的新方法. 该法通过计算和分析分子离子自旋密度, 进而比较从中性分子到分子离子的电荷变化和键长变化, 从而确定初始电离位点. 对简单吲哚类生物碱质谱的特征裂解机理进行了预测, 结果与标准物质的质谱吻合. 在此基础上, 与传统的根据基团电离能确定电离位点的方法进行了比较. 结果表明, 该法优于电离能方法. 此法不仅可用于预测以α-裂解为主导的吲哚生物碱和其它含氮化合物的质谱裂解规律, 还为揭示其它小分子化合物以及气相多肽离子的裂解机理奠定了基础.     

厚壁管道周向导波检测技术实验研究

厚壁管道是火电机组四大管道系统的核心部件,将超声导波技术应用于厚壁管道的无损检测显得十分重要.首先确定厚壁管道检测的激励方式,优化选取适合厚壁管道检测的0.5MHz探头和楔形块角度为60°的斜探头组合.通过改变斜探头与外壁轴向缺陷之间周向距离,在一定范围内仍可检测到缺陷回波,且接收到的周向回波幅值变化不大,表明周向导波...     

An experimental investigation into non-linear wave loading on horizontal axis tidal turbines

Tidal turbines are subject to large hydrodynamic loads from combinations of currents and waves, which contribute significantly to fatigue, extreme loading and power flow requirements. Physical model testing enables these loads and power fluctuations to be assessed and understood in a controlled and repeatable environment. In this work, a 1:15 scale tidal turbine model is utilised to further the fundamental understanding of the influence of waves on tidal turbines. A wide range of regular waves are generated in both following-current and opposing-current conditions. Wave frequencies range from 0.31 Hz to 0.55 Hz & wave heights from 0.025 m to 0.37 m in a fixed 0.81 m/s current velocity. Waves are selected and programmed specifically to facilitate frequency domain analysis, and techniques are employed to isolate the effect of non-linear waves on turbine power and thrust.Results demonstrate that wave action induces large variations in turbine power and thrust compared to current only conditions. For the range of conditions tested, peak values of thrust and power exceed current-only values by between 7%–65% and 13%–160% respectively. These wave-induced fluctuations are shown to increase with wave amplitude and decrease with wave frequency. Following wave conditions exhibit greater variations than opposing for waves with the same wave height and frequency due to the lower associated wavenumbers.A model is developed and presented to aid the understanding of the high-order harmonic response of the turbine to waves, which is further demonstrated using steady state coefficients under assumptions of pseudo-stationarity. This approach is proven to be effective at estimating wave-induced power and thrust fluctuations for the combinations of waves, currents and turbine state tested. The outcome of which shows promise as a rapid design tool that can evaluate the effect of site-specific wave–current conditions on turbine performance.