冰碛物电子自旋共振信号测量的基本流程

电子自旋共振（ESR）法是一种用于直接测量和研究含有未成对电子的顺磁性物质的分析方法。ESR测年是应用这种分析方法对沉积物最后一次埋藏以来的年代进行测定。相比于其他方法,它具有测年范围广,测试的样品种类多,样品可以重复测量,测量周期短等优势。20世纪80年代以来我国开始进行沉积物ESR测年与研究,但是在冰碛物ESR测年的制样和测量过程中存在一些问题。本文介绍冰碛物ESR测年的过程：样品野外采集时剖面的选取及其注意事项;详细描述提纯冰碛物中石英颗粒的前处理过程;石英颗粒经过人工辐照后在顺磁波谱仪上测试ESR信号并拟合古剂量过程中的具体方法和需要注意的问题。从实验中得到,用0.063 —0.125 mm粒径的组分提纯石英砂比较困难,前处理过程中试剂和时间消耗量大,因此建议ESR测年时：在样品充足的情况下选用细颗粒组分（0.063—0.125 mm）,样品不充足的情况下选用中颗粒部分（0.125—0.25 mm）。待测样品中存在其他矿物会对石英的ESR信号有影响,因此在提纯石英过程中用重液分选提高石英纯度并可以增强测量的ESR信号的稳定性。经过氢氟酸刻蚀后的样品,石英的纯度要达到95%—99%或以上。对于冰碛物ESR测年过程中ESR信号的选择需要参照样品自身的特点,综合考虑多次尝试才能确定用常温Ge心信号还是低温的Al心、Ti心作为样品中石英的ESR测年信号。通过规范的采样、制样和ESR信号测量流程,使样品的定年能够被不同的人重复,并能够进行不同区域之间的对比。     

ESR技术应用于逆胶束酶体系性能的研究

采用鼠李糖脂构建逆胶束体系,并利用电子自旋共振（ESR）技术研究了鼠李糖脂逆胶束及鼠李糖脂逆胶束酶体系的性能.采用ESR光谱技术计算得出逆胶束体系中超精细分裂常数变化,研究表明鼠李糖脂在正己烷中的临界胶度为0.07mmol/L.通过分析ESR光谱中旋转相关时间的变化,探究电子自旋探针在逆胶束中运动受阻和翻转所需时间的情况同时,ESR光谱的峰值体现了样品中自由基含量的多少.通过对比逆胶束体系、逆胶束酶体系以及逆胶束酶-苯酚体系的ESR光谱,结果表明鼠李糖脂逆胶束-苯酚体系的自由基最多.通过研究对16-氮氧自由基硬脂酸对两个体系作用,推测出电子自旋探针自由基团定位于逆胶束水核中,并且推断电子自旋探针位于水核的边缘区域,即结合水水层.该研究为逆胶束酶体系的应用提供了坚实的理论基础.     

Quantification of human amniotic fluid constituents by high resolution proton nuclear magnetic resonance (NMR) spectroscopy

We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained.     

石英不同Ti-Li心电子自旋共振信号光晒退特征及其测年意义

为探讨石英不同Ti-Li心电子自旋共振（ESR）信号的光晒退特征及其测年意义,对典型花岗岩类基岩样品、河流现代表层沉积物样品及地质历史时期沉积物样品的石英Ti-Li心option A、Ti-Li心option B、Ti-Li心option C、Ti-Li心option D和Ti-Li心option E的ESR信号光晒退特征进行了系统研究。结果显示：（1）不同Ti-Li心ESR信号可在较短时间内（260 h）完全晒退,表明Ti-Li心是优良的石英ESR测年信号心;（2）石英的赋存环境对同一Ti-Li心ESR信号晒退“归零”所需的时间具有明显的影响作用。相比于基岩石英和地质历史时期沉积物石英,现代河流沉积物石英因其已经接受了一定时间的光晒退作用而具有更快的光晒退“归零”速率;（3）石英同一Ti-Li心的光敏感特性会因石英经历的地质循环过程的不同而改变,相比于基岩,沉积物因经历了更复杂的地质过程而具有了深陷阱电子,所以需要更长的光晒退归零时间;（4）同一样品的不同Ti-Li心表现出了相同的光晒退特征,说明不同类型的Ti-Li心具有相同的光敏特性;（5）Ti-Li心option B在某些自然样品中不易观察,Ti-Li心option D和Ti-Li心option E信号较为微弱,因此,Ti-Li心option A是进行沉积物石英ESR测年的最佳信号心。     

Magnetic resonance spectroscopy of the fetal brain

Fetal magnetic resonance spectroscopy (MRS) is technically feasible in utero and demonstrates similar findings to those observed in neonatal populations. MRS can provide additional information to conventional T1- and T2-weighted imaging of the fetal brain. It is of particular use when subtle changes are present on conventional fetal MRI sequences, and when imaging fetuses at risk of brain injury and metabolic abnormalities. Copyright © 2009 John Wiley & Sons, Ltd.     

用电子自旋探针研究水泥固化土壤中镉离子的反应

应用电子自旋探针（Ｅｌｅｃｔｏｒｏｎ ｓｐｉｎ ｐｒｏｂｅ，简ＥＳＰ）Ｍｎ＾２＋离子的超精细结构（ｈｙｐｅｒｆｉｎｅ ｓｔｒｕｃｔｕｒｅ，简称ｈｆｓ），揭示了水泥固化土壤中Ｃｄ＾２＋离子的化学反应，研究发现：由于水泥水化产生高的ＰＨ值，Ｃｄ＾２＋离子与ＯＨ＾－离子反应生成Ｃｄ（ＯＨ）２沉‘当有ＣＯ２气体存在时，Ｃｄ＾２＋离子会与ＣＯ２和水泥水化的ＯＨ＾－离子反应生成ＣｄＣＯ３、Ｃｄ（ＯＨ）２，这些     

High resolution proton NMR spectroscopy of human amniotic fluid

Human amniotic fluid (HAF) is a dynamic system whose characteristics depend on continuous interchanges between fetal and maternal circulations. HAF reflects not only the environment of the fetus but may also provide information about fetal development or pathology. The concentration of HAF constituents varies with gestational age and pathological states. The number of the compounds currently implicated in fetal developmental pathology are relatively few. Currently used assay methods are not adequate to totally explain or predict the complex biochemistry of the fetus. The purpose of this work was to investigate HAF with NMR spectroscopy. In the present study HAF was obtained from 47 women undergoing routine amniocentesis. Cells were separated for karyological analysis and the supernatant was acid-extracted, lyophilized and re-suspended in D₂0 resulting in a concentration increase over native fluid. ¹H NMR spectra were obtained at 360 MHz and 60 MHz. Eighteen compounds including several amino acids, were identified using parallel reference and standard addition protocols. NMR spectroscopy detected compounds of known clinical importance including glucose, leucine, isoleucine, lactate and creatinine. In conclusion, we have demonstrated that a number of physiologically relevant compounds are readily observable in HAF using ¹H NMR spectroscopy. This technique can currently provide valuable information regarding HAF composition and has the potential of being used in vivo in the future.     

年轻地下水定年研究综述

将环境示踪技术用于地下水定年以确定地下水的相关时间尺度问题在过去几十年中得到了长足发展,尤其是在年轻地下水定年方面。目前国内外用到的年轻地下水环境示踪剂有多种,这些示踪剂在地下水定年方面各有利弊。本文的目的是对国内外现有的9种年轻地下水示踪剂(3 H、3 H/3 He、4 He、35S、36 Cl/Cl、85 Kr、222 Rn、CFCs和SF6)的来源、示踪原理、误差来源、优缺点、适用性和应用现状等进行归纳和总结,为研究者、管理者和决策者在应用时提供参考。     

五氯酚钠及二(口恶)(口英)残留毒物对人外周血淋巴细胞的影响

采用彗星试验和微核试验,协同探索了五氯酚钠(Na-PCP)、二(口恶)(口英)类物质联合作用对血吸虫病流行区和正常生活区的人体外周血淋巴细胞影响效应.结果表明,实际用药区居民的外周血淋巴细胞以及用五氯酚钠与二(口恶)(口英)类物质联合作用处理过的正常人外周血淋巴细胞,其彗星率与微核率均高于对照组,在一定浓度范围内有剂量效应关系;基本的联合毒性作用推测为Na-PCP中的杂质PCDs与PCDFs等多种化学物质会损伤人体外周血淋巴细胞的DNA,其毒性作用比单一的二(口恶)(口英)类物质作用强.     

Prenatal diagnosis of the infantile type of neuronal ceroid lipofuscinosis by electron microscopic investigation of human chorionic villi

Chorionic villus biopsy specimens were studied electron microscopically in six pregnancies at risk of the infantile type of neuronal ceroid lipofuscinosis (INCL). The biopsy was performed in all cases in the first trimester of pregnancy (8–10 gestation weeks) by the transcervical route. In one case, the biopsy was repeated at 17 weeks by the transabdominal procedure. In two pregnancies, the endothelial cells and, to a lesser extent, the mesenchymal cells of the chorionic villi contained unit membrane-bound inclusions typical of INCL. In both cases, the pregnancy was terminated and in one of them identical inclusions were found in the brains and kidneys of the fetus at 20 weeks of gestational age. The children from the remaining four pregnancies are healthy and have shown no signs of the disease.