Sauna,sweat and science II – do we sweat what we drink?

ABSTRACT

Inspired by a previous ‘Sauna, sweat and science’ study [Zech et al. Isot Environ Health Stud. 2015;51(3):439–447] and out of curiosity and enthusiasm for stable isotope and sauna research we aimed at answering the question ‘do we sweat (isotopically) what we drink’? We, therefore, pulse-labelled five test persons in a sauna experiment with beverages that were ²H-enriched at about +25,600?‰. Sweat samples were collected during six sauna rounds and the hydrogen isotope composition δ²H_sweat was determined using an isotope ratio mass spectrometer. Before pulse labelling, δ²H_sweat – reflecting by approximation body water – ranged from –32 to –22?‰. This is ～35?‰ enriched compared to usual mid-European drinking water and can be explained with hydrogen-bearing food as well as with the respiratory loss of ²H-depleted vapour. The absence of a clearly detectable ²H pulse in sweat after pulse labelling and δ²H_sweat results of ≤+250?‰ due to a fast ²H equilibration with body water are moreover a clearly negative answer to our research question also in a short-term consideration. Given that the recovery of the tracer based on an isotope mass balance calculation is clearly below 100?%, we finally answer the question ‘where did the rest of the tracer go?’     

Using a water-confined carbon nanotube to probe the electricity of sequential charged segments of macromolecules

The detection of macromolecular conformation is particularly important in many physical and biological applications. Here we theoretically explore a method for achieving this detection by probing the electricity of sequential charged segments of macromolecules. Our analysis is based on molecular dynamics simulations, and we investigate a single file of water molecules confined in a half-capped single-walled carbon nanotube (SWCNT) with an external electric charge of +e or -e (e is the elementary charge). The charge is located in the vicinity of the cap of the SWCNT and along the centerline of the SWCNT. We reveal the picosecond timescale for the re-orientation (namely, from one unidirectional direction to the other) of the water molecules in response to a switch in the charge signal, -e → +e or +e →-e. Our results are well understood by taking into account the electrical interactions between the water molecules and between the water molecules and the external charge. Because such signals of re-orientation can be magnified and transported according to Tu et al. [2009 Proc. Natl. Acad. Sci. USA 106 18120], it becomes possible to record fingerprints of electric signals arising from sequential charged segments of a macromolecule, which are expected to be useful for recognizing the conformations of some particular macromolecules.     

Uptake of Europium(III) from Water using Magnetite Nanoparticles

It is demonstrated that colloidal magnetite nanoparticles can be used as nanosorbents for lanthanide ions dissolved in water. In particular, a series of experiments are performed for the removal of Eu(III) in distinct analytical conditions and by applying an external magnet to collect the sorbents previously dispersed in water samples. Furthermore, strategies for surface chemistry functionalization are also investigated, aiming to investigate the effect of this parameter on the removal capacity of the Fe₃O₄ nanoparticles. The supernatant solutions are monitored for the remaining amount of Eu(III) by fluorescence emission measurements in the presence of 2,6‐pyridinedicarboxylic acid as a sensitizer. The results demonstrate that neat Fe₃O₄ nanoparticles are capable of capturing lanthanide ions (III) from aqueous solutions (pH 7), without need of surface modification, and for subsequent removal by magnetic separation. During the removal, efficiency is increased after modifying the particles' surfaces with silica and 3‐aminopropyltrimethoxysilane; in alkaline medium (pH 10), there is complete removal regardless the type of nanosorbent used. This has been explained by the formation of insoluble Eu(III) species that adsorb strongly to the nanosorbents surfaces allowing their subsequent magnetic separation.     

表/界面水的扫描探针技术研究进展

表面和界面水在自然界、人们的日常生活以及现代科技中无处不在.它在物理、化学、环境学、材料学、生物学、地质学等诸多基础学科和应用领域起到至关重要的作用.因此,表面和界面水的功能与特性的研究,是水基础科学的一项核心任务.然而,由于水分子之间氢键相互作用的复杂性,及其与水-固界面相互作用的竞争,使得表(界)面水对于局域环境的影响非常敏感,往往需要深入到分子层次研究其微观结构和动力学过程.近年来,新型扫描探针技术的发展使得人们可以在单分子甚至亚分子尺度上对表(界)面水展开细致的实空间研究.本文着重介绍几种代表性的扫描探针技术及其在表(界)面水体系中的应用,包括:超高真空扫描隧道显微术、单分子振动谱技术、电化学扫描隧道显微术和非接触式原子力显微术.此外,本文还将对表(界)面水扫描探针技术研究面临的挑战和未来发展方向进行了展望.     

An efficient splitting technique for two‐layer shallow‐water model

We consider the numerical approximation of the weak solutions of the two‐layer shallow‐water equations. The model under consideration is made of two usual one‐layer shallow‐water model coupled by nonconservative products. Because of the nonconservative products of the system, which couple both one‐layer shallow‐water subsystems, the usual numerical methods have to consider the full model. Of course, uncoupled numerical techniques, just involving finite volume schemes for the basic shallow‐water equations, are very attractive since they are very easy to implement and they are costless. Recently, a stable layer splitting technique was introduced [Bouchut and Morales de Luna, M2AN Math Model Numer Anal 42 (2008), 683–698]. In the same spirit, we exhibit new splitting technique, which is proved to be well balanced and non‐negative preserving. The main benefit issuing from the here derived uncoupled method is the ability to correctly approximate the solution of very severe benchmarks. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 1396–1423, 2015     

超声乳化晶状体摘除术对不同阶段原发性闭角型青光眼的疗效分析

目的 比较分析超声乳化晶状体摘除术对不同阶段的原发性闭角型青光眼的治疗效果,为临床上闭角型青光眼行 晶状体摘除术治疗的手术时机选择提供依据。方法 收集2008 年7 月至2013 年12 月行超声乳化晶状体囊外摘除术联合人工晶状体植入术的闭角型青光眼患者70 例（共113 眼）,分为临床前期组（40 眼）、急性发作组（48 眼）和慢性进展组（25 眼）3 组,平均随访（19.47±10.10）个月。比较各组患者术前、术后的视力、眼压、视野、房角粘连等参数,以及术后随访过程中青光眼继续进展的情况。结果 临床前期组患者术后均无青光眼进展;急性发作组10.4%患者术后继续进展,继续进展和术前病程相关（r=0.462,P＝0.003）;慢性进展组40.0%患者术后继续进展,继续进展和房角粘连程度相关（r=0.698,P＝0.000）。结论 原发性闭角型青光眼临床前期患者进行晶状体摘除可良好地预防青光眼进展;房角关闭急性发作时尽早行晶状体摘除;慢性进展期在早期,房角粘连未达1/2周之前行晶状体摘除均可有效控制病情发展。     

超导Tl2Ba2CaCu2O8+x 薄膜的太赫兹复电导率的提取

采用低温太赫兹时域光谱系统, 测试了高温超导 Tl2Ba2CaCu2O8+x 薄膜的太赫兹透射谱, 并提取了它在不同温度下的太赫兹电导率. 研究过程中发现提取后的参数存在电导率随频率波动大、与理论值偏差较大等问题.通过对基片厚度和太赫兹波入射角度的误差对高温超导薄膜电导率的影响进行了分析, 结果表明导致数据波动大是由于基片厚度的偏差引起的. 针对厚度差的影响, 一种矫正方法被提出, 通过对厚度的修正, 提高了数据提取的质量.     

非有机溶剂萃取催化光度法测定锰Mn(Ⅱ)-H2O2-EBT-PEG-2000体系

研究了碱性介质中,利用锰(Ⅱ)催化过氧化氢氧化铬黑T的指示反应。用聚乙二醇-2000非有机溶剂萃取平衡控制反应时间和指示反应进行的程度。通过测量酸性条件下539nm处聚乙二醇-2000相的吸光度,建立了非有机溶剂萃取催化光度法测定痕量锰(Ⅱ)的新方法。方法的线性范围为0.0080~0.55μg.mL-1,检测限为3.0×10-9g.L-1,可用于铝合金、茶叶样品中锰的测定。     

基于跟踪度的Gabor小波特征跟踪方法的研究

图像的边缘包含了目标的大量特征信息。利用Gabor小波可以从目标图像中提取具有特征位置、角度和尺度的参数。利用这些参数可以重建除均值以外的所有图像信息。图像边缘与均值无关。根据重建图像边缘线段的长度和边缘拟和度以及特征点的个数,提出了跟踪度的概念,分析了跟踪度的性质,并在跟踪度准则指导下确定了跟踪的特征点个数。仿真实验证明,跟踪度反映了目标特征跟踪的可靠程度,提供了跟踪精度的客观标准,为选择特征点个数、平衡计算复杂度和跟踪精度提供了客观的依据。通过对目标进行姿态变换和大面积遮挡的跟踪实验证明,当跟踪度达到0 95以上时就可以稳定地跟踪目标。     

经典单色短峰水波理论的三阶完备解

针对经典的有限水深三阶单色短峰波,考虑环境均匀流效应,赋予一新的解析解,从而与原经典解析解构成完备的解析解.这就在第二阶解、第三阶解结构上显示出多种相互作用机制.