核磁共振实验教学内容的重组与优化

探索研究了一种将连续核磁共振和脉冲核磁共振有机融合的实验教学方法.在实验中,利用多媒体课件展示核磁共振的物理原理,学生分别采用连续和脉冲核磁共振方法测量同样浓度的CuSiO4水溶液的表观弛豫时间和横向弛豫时间,了解样品浓度、磁场非均匀度等因素对横向弛豫时间测量的影响.     

氧化物纳米材料表面结构与性质的固体核磁共振波谱研究

氧化物纳米材料的多种应用与其表面结构和性质密切相关.近年来,固体核磁共振波谱在相关研究中提供了关键信息.本综述总结了近期发展的、以固体核磁共振波谱为主的两种表征氧化物纳米材料表面结构和性质的方法,包括表面选择的同位素标记¹⁷O核磁共振波谱与动态核极化表面增强核磁共振波谱,并对氧化物纳米材料的固体核磁共振波谱研究的发展趋势进行了展望.     

核磁共振成像及其医学应用

介绍了核磁共振现象、核磁共振成像的物理原理和特点,简明概述了它在临床诊断上的应用及发展前景。     

原位液体核磁共振在高分子材料表征领域的应用

随着原位系统研究的进步以及灵敏度的提高，原位核磁共振在高分子材料领域的应用越来越广泛.原位液体核磁共振具有分析速度快、适用范围宽、无损检测、无需标样等特点，多用于表征聚合反应动力学及反应机理.除此之外，它还可以通过与其他仪器进行联用、匹配适用的探头等手段分离并解析未知物的化学结构.因此，原位液体核磁共振波谱技术将成为高分子科学研究领域不可或缺的通用工具.     

核磁共振分析技术在石化领域中的应用

运用高分辨核磁共振技术解决了许多难以使用其他仪器方法测定的石化产品或催化材料的结构及组成分析问题. 分析实验表明,核磁共振技术在石化工业发展中已经成为强有力的研究分析工具.     

固体核磁共振魔角旋转条件下的定量交叉极化技术(英文)

交叉极化与魔角旋转结合（CP/MAS）的方法已经成为增强固体核磁共振（NMR）检测灵敏度最重要的技术之一.CP/MAS技术的应用大大提高了固体NMR谱图的采集效率.然而,I-S偶极耦合作用、旋转坐标系下的自旋-晶格弛豫、分子运动,以及样品中丰核的分布情况等因素,通常会导致CP/MAS谱图失去定量作用.近年来,多个研究组通过改进或者设计新型固体NMR脉冲序列,获得了基于CP的可用于定量分析的固体NMR谱图.本综述首先简要介绍了CP及CP动力学,随后介绍了一系列基于CP的定量固体NMR信号增强技术,具体包括ramped-amplitude CP（RAMP-CP）、multiple-contact CP、quantification of CP（QCP）、Lee-Goldburg frequency modulated CP（LG-FMCP）和quantitative CP（QUCP）.     

聚醚改性有机硅表面活性剂的核磁共振及红外光谱表征

通过核磁共振技术(1H,13C NMR,DEPT135,COSY,HSQC,HMBC)和红外光谱技术(FT-IR),对未知的有机硅表面活性剂商品(NPS-A)进行了表征;结果表明:该表面活性剂是单烯丙基聚乙二醇(AllyloxyPolyEthylene Glycol,APEG)在聚硅氧烷侧链改性所得,样品中含有合成时所带的大量DMSO溶剂(合成时所代入的),除溶剂外的主要成分为:(1)M-D20-(D′R)6-M(M:三甲基硅氧基;D:二甲基硅氧基;D′:取代的二甲基硅氧基),其中R=CH2CH2CH2-O-(EO)8-H,平均分子量(M_n)为4 046.0,(2)APEG(M_n=410.0)和(3)聚乙二醇(PolyEthylene Glycol,PEG,M_n=370.0),同时还含有少量由烯丙基衍生而来的小分子成分.     

脉冲核磁共振观测方法的改进

由于脉冲核磁共振实验对系统的环境温度极为敏感,磁体温漂和环境温度变化都会引起共振点的漂移．为了更准确地进行数据采集,改用存储示波器替代脉冲核磁共振系统配套软件进行实时跟踪观测,选择通用软件进行数据处理．此外,加入噪声因子对数据进行去噪处理,可以获得更准确的实验结果．     

核磁共振YBCO表面探测线圈的设计与制备

本文采用２０×２０ｍｍ的ＹＢＣＯ／ＬａＡｌＯ３薄膜,采用传统的光刻技术制备出了可用于探测核磁共振的超导线圈．并且在７７Ｋ的低温下测量的其ｆ０及Ｑ值．其ｆ０为３５２ＭＨｚ,Ｑ值为１５０．本文还介绍了器件的设计和分析考虑、器件的加工工艺及实验结果讨论     

核磁共振测量乙醇汽油低含水量的实验探索

为了探索利用核磁共振技术测量乙醇汽油低含水量的方法,测量了不同含水量乙醇汽油的核磁共振横向弛豫时间,发现横向弛豫时间不随含水量的变化而呈现一定规律性的变化,因而尝试加入NH4NO3、NaOH、CuSO4和MnCl2.4H2O来扩大含水量对核磁共振横向弛豫时间的影响。实验结果表明：加入MnCl2.4H2O可使横向弛豫时间随含水量的增加而增加,并拟合出了相应的经验公式。在此基础上提出了乙醇汽油低含水量的核磁共振测量方法,通过测量实例验证了这一方法的有效性和可靠性。     

One-step synthesis of hydrophobic mesoporous silica and its application in nonylphenol adsorption

Highly CH₃-functionalized mesoporous silica with nearly spherical morphology was synthesized under acidic conditions by co-condensation of two different silica precursors polymethylhydrosiloxane (PMHS) and tetraethoxysilane (TEOS) in the presence of triblock copolymer P123 as template. XRD, N₂ adsorption–desorption, HRTEM, SEM and ²⁹Si MAS NMR were used to identify its highly-ordered mesopore array structure, nearly spherical particle morphology and CH₃ functionalization of the as-synthesized material. The resulting hydrophobic mesoporous silica possessed regular mesochannel arrays, indicating that the introduction of PMHS had little impact on the formation of an ordered mesostructure. Also, PMHS played an important role in morphology control and organic functionalization, ensuring nearly spherical particle morphology and high CH₃ functionalization degree of the obtained mesoporous silica material. As compared with pristine mesoporous silica SBA-15, the hydrophobic mesoporous silica showed the higher adsorption performance when they were used as adsorbents to remove organic pollutant nonylphenol at a very low concentration from aqueous solution.     

Modelling of dynamical processes in a molecular crystal by NMR

In this contribution we report on the plastic crystal 1-chloroadamantane dynamics via conventional frequency dependent (¹H and ¹³C) and field cycling NMR measurements. A suitable microscopic dynamical model, worked out from from X-ray analysis is developed and the molecular motions are interpreted in terms of: self diffusion and dipolar molecular axis combined with uniaxial rotation. In the rotator phase the molecules execute a bimodal reorientation process whereas the uniaxial rotation solely persists in the low temperature phase. In both phases, the residence times exhibit an Arrhenius temperature dependence. The results confirm the existence of a dynamic crossover transition predicted by molecular dynamics simulation.     

Probing spatial correlations in the inhomogeneous glassy state of the cuprates by Cu NMR

We discuss the crossover of the form of the Cu Nuclear magnetic resonance (NMR) spin echo decay at the onset of Cu wipeout in lanthanum cuprates. Experimentally, the echo decay undergoes a crossover from Gaussian to exponential form below the temperature where the Cu NMR intensity drops. The wipeout and the change in behavior both arise because the nuclei experience spatially inhomogeneous spin fluctuations at low temperatures. We argue that regions where the spin fluctuations remain fast are localized on length scales of order 1-2 lattice spacings. The inhomogeneity is characterized by the local activation energy E_a(r); we estimate the functional form of E_a(r) for points where E_a>(r)∼0.     

The influence of NH3 -attaching on the NMR parameters in the zigzag BN nanotube

Two models of (10, 0) boron nitride nanotubes (BNNTs), perfect and Ammonia-attached, were studied in order to evaluate the influence of NH₃-attaching on the B-11 and N-15 nuclear magnetic resonance in the (10, 0) boron-nitride nanotube (BNNT) for the first time. At first, based on density functional theory (DFT) each of the structures was optimized using B3LYP/6-31G (d) model chemistry. At the next step, the chemical-shielding (CS) tensors were calculated using the B3LYP/6-31G (d, p) level of theory in both of the relaxed forms and were converted to experimentally measurable nuclear magnetic resonance (NMR) parameters, i.e. chemical-shielding isotropic (CSI) and chemical-shielding anisotropic (CSA). Our calculation revealed that in the NH₃-attached BNNT (the most stable model) the B atom chemically bonded to the NH₃ molecule has the largest chemical-shielding isotropic (CSI) and the smallest chemical-shielding anisotropic (CSA) values among the other boron nuclei. Additionally, the NMR parameters of those nuclei directly bonded to the boron dramatically change while those of the other B nuclei remain almost unchanged.     

Lateral diffusion in equimolar mixtures of natural sphingomyelins with dioleoylphosphatidylcholine

Cellular membranes of mammals are composed of a complex assembly of diverse phospholipids. Sphingomyelin (SM) and phosphatidylcholine (PC) are important lipids of eukaryotic cellular membranes and neuronal tissues, and presumably participate in the formation of membrane domains, known as "rafts," through intermolecular interaction and lateral microphase decomposition. In these two-dimensional membrane systems, lateral diffusion of lipids is an essential dynamic factor, which might even be indicative of lipid phase separation process. Here, we used pulsed field gradient nuclear magnetic resonance to study lateral diffusion of lipid components in macroscopically oriented bilayers composed of equimolar mixtures of natural SMs of egg yolk, bovine brain, bovine milk and dipalmitoylphosphatidylcholine (DPPC) with dioleoylphosphatidylcholine (DOPC). In addition, differential scanning calorimetry was used as a complementary technique to characterize the phase state of the lipid bilayers. In fully liquid bilayers, the lateral diffusion coefficients in both DOPC/DPPC and DOPC/SM systems exhibit mean values of the pure bilayers. For DOPC/SM bilayer system, this behavior can be explained by a model where most SM molecules form short-lived lateral domains with preferential SM-SM interactions occurring within them. However, for bilayers in the presence of their low-temperature gel phase, lateral diffusion becomes complicated and cannot simply be understood solely by a simple change in the liquid phase decomposition.     

F 2-FDG NMR imaging of the brain in rat

Images of the rat head reflecting glucose utilization were obtained using 2-fluoro-2-deoxy-D-glucose (2-FDG) and ¹⁹F nuclear magnetic resonance (NMR) imaging. Spatial heterogeneity of glucose utilization in the rat head was clearly demonstrated showing significantly higher glucose utilization in the brain as compared to the surrounding tissues. Although the potential adverse effects of the high doses of 2-FDG (400 mg/kg) needed to perform the study preclude immediate application of this technique to clinical quantitative glucose utilization studies, the present study shows potential for future development of glucose utilization imaging by NMR.     

液晶环境下金纳米柱的表面等离子体特性研究

为了有效研究液晶环境对金属纳米结构表面等离子体的调制作用,基于时域有限差分方法,对液晶环境下金纳米柱结构进行了建模,上下边界采用完全吸收边界条件,四周为周期边界条件.数值模拟了液晶厚度、倾角、光栅距离以及周期结构等参数对金纳米柱的消光特性的调制作用.分析结果表明:随着液晶光轴角度增加,谐振波长出现红移现象,且调制范围为40nm;光栅距离越大,金纳米柱之间的相互作用越弱,谐振波长越小;增加周期长度,谐振波长红移,且随着周期长度增加,次峰作用越明显.利用液晶光学性质可调节金属纳米结构的表面等离子体特性,结果对液晶环境中表面等离子体结构在新的光子器件等方面的研究提供了理论依据.     

超光滑加工技术中光学元件表面材料的均匀去除

超光滑加工通常是在保证光学元件面型精度不劣化前提下提升其中高频精度.均匀去除是保证超光滑加工过程中光学元件面型精度不劣化的重要途径.本文以四轴三联动小磨头超光滑加工机床为基础,结合Preston假设,研究了四轴三联动超光滑加工机床对光学元件的材料去除特性,发现当机床取某些特定的参量时,通过等值的驻留时间规划即可实现光学元件表面材料的均匀去除.最后,对这些特定的参量进行了对比实验.实验结果验证了理论分析的正确性.