煤的核磁共振成象研究

通过分别浸泡在氘代吡啶和氘代丙酮溶剂中的煤的核磁共振成象,观察了溶剂在煤中的渗透、扩散过程和溶胀作用。并得到了煤的大分子网络中的动态小分子的分布情况。由核磁共振成象技术获得了煤的化学和物理结构信息。     

基于MATLAB开发的核磁共振波谱信息库

基于核磁共振原理及NMR谱图的解析和检索方法，利用MATLAB语言的开放式可扩充式体系结构特点，介绍了核磁共振波谱图谱信息库的特点、设计方法、技术处理及系统应用。     

肌酐纯度标准物质的定值方法及其不确定度评定研究

通过定性及定量分析,研究了肌酐纯度标准物质的定值方法,并进行了定值分析的不确定度评定。首先使用三重四极杆质谱仪及核磁共振谱仪(氢谱)对肌酐样品进行定性分析,然后采用质量平衡法(包括液相色谱法、水分、灰分、挥发性物质和无机元素分析)与定量核磁共振法共同对肌酐纯度标准物质进行准确定值,最后对定值结果进行不确定度评定。肌酐的定值结果为99.7%,扩展不确定度为0.4%。该研究对于实际检测中肌酐的准确测定及临床上相关疾病的正确诊断治疗具有重要意义,且经过定值的肌酐纯品还可做定量核磁共振法的定量内标使用。定量分析后的肌酐经过均匀性检验和稳定性考察后可申报为国家标准物质。     

原位电化学与核磁共振联用新技术及其应用进展

电极表面微观的电化学反应动力学机制无法通过孤立的传统电化学方法直接揭示,核磁共振技术能在分子水平上提供待测样品的化学位移和J耦合产生的微小分裂等信息,它可以更容易地鉴定同分异构体、分子构象和电子变化。因此,原位电化学与核磁共振联用技术可以从分子层面上对物质反应机理和反应动力学过程进行原位无损实时研究,发现非原位技术无法监测的短寿命中间体,揭示反应机理和构效关系等相关信息,是一种非常有发展前途的原位谱学技术。但是由于电化学池和核磁共振的不兼容性,对原位电化学与核磁共振的研究及应用相对较少,为了让更多的人了解原位电化学与核磁共振联用这一新技术,文章分别阐述了该技术的国内外进展、工作原理、面临的挑战及其在电化学催化及物质反应机理、燃料电池和药物研究等方面的应用,并对今后需要解决的关键性问题进行了展望。     

关于聚皂共聚物组成的核磁共振研究

烷基甲基二烯丙基溴化铵共聚物是一种新型疏水改性的聚皂,应用多种核磁共振分析技术对其结构和共单体的组成进行了定量的讨论.研究结果表明,在测定化学结构和性质上比较接近的共单体组成时,核磁共振方法是一种有效的工具.     

核磁共振法鉴定表面活性剂

对7种常见的表面活性剂及其二元复配体系进行了核磁共振(NMR)分析,探索了多组分表面活性剂复配物的5种分离方法,比较了这5种分离方法对二元组分表面活性剂复配物的分离效果,并初步建立了核磁共振法分析多元表面活性剂复配产品的方法.采用该方法对3种企业样品中的表面活性剂进行了NMR测试,确认了各表面活性剂1H NMR的谱峰归...     

Bruker 400 MHz核磁共振波谱仪的维护及常见故障探讨

核磁共振（nuclear magnetic resonance,NMR）法可以鉴定化合物的结构和组分,并在反应过程监控等方面提供强有力的支撑,得到了广泛应用.结合核磁共振波谱仪的实际使用情况,对波谱仪的日常维护、常见故障以及排查方法进行探讨,为更好地使用和维护仪器提供一种思路.     

一种新型含卤高聚物光解成象体系

我们在研究含卤高聚物光解过程中,发现了一种新型非银盐成象体系(简称VMD体系)。该体系是利用含卤高聚物感光膜经紫外光(2537(?))通过掩模曝光后,在水中,曝光区变白,未曝光区依然保持透明,从而达到记录图象的目的。     

核磁共振法测定高聚物的结构—核磁共振二维谱

介绍了核磁共振(NMR)波谱,尤其是核磁共振二维谱(2D NMR)在最近几年内的进展。内容包括怎样用NMR测定高聚物的序列分布、共聚物结构、聚合物的混溶性、聚合物液晶的取向度、分子量、短链度和长链支化度、凝聚态高聚物的多相结构等。     

PBT/PEG型聚醚酯的鉴定

采用红外光谱、核磁共振和DSC热分析手段对一种未知聚合物样品进行表征。通过对样品红外谱图的吸收峰位和强度及对其核磁共振氢谱中各质子化学位移归属的分析,判明该样品为PBT/PEG型聚醚酯弹性体,且不含游离的聚乙二醇组分。样品的DSC测试表明其与PBT/PEG型聚醚酯的热行为较相符。该分析为此类聚合物提供了一种简单、快速且结果可靠的鉴定方法。     

Desktop NMR and Its Applications From Materials Science To Organic Chemistry

NMR spectroscopy is an indispensable method of analysis in chemistry, which until recently suffered from high demands for space, high costs for acquisition and maintenance, and operational complexity. This has changed with the introduction of compact NMR spectrometers suitable for small‐molecule analysis on the chemical workbench. These spectrometers contain permanent magnets giving rise to proton NMR frequencies between 40 and 80 MHz. The enabling technology is to make small permanent magnets with homogeneous fields. Tabletop instruments with inhomogeneous fields have been in use for over 40 years for characterizing food and hydrogen‐containing materials by relaxation and diffusion measurements. Related NMR instruments measure these parameters in the stray field outside the magnet. They are used to inspect the borehole walls of oil wells and to test objects nondestructively. The state‐of‐the‐art of NMR spectroscopy, imaging and relaxometry with compact instruments is reviewed.     

Nuclear magnetic resonance studies of solvent flow through chromatographic columns: effect of packing density on flow patterns

NMR (nuclear magnetic resonance) techniques have been used to measure and characterise solvent flow through chromatographic columns. NMR imaging was used to track an injection of D2O. PGSE (pulsed gradient spin echo) NMR was used to measure the flow-rate dependence of axial and transverse apparent diffusion. A combination of these two techniques (dynamic NMR imaging) gave the spatial distribution of the local velocity and apparent diffusion through a cross-section of the column. Significant column wall effects were observed and these effects were found to be highly dependent upon the column packing density. The column performance was assessed in terms of the HETP (height equivalent to a theoretical plate) determined by the NMR techniques employed.     

NMR imaging of polyethylene pipes

¹H nuclear magnetic resonance (NMR) imaging techniques have been used to image the extrusion aid (EA) in polyethylene (PE) pipe samples. The resulting two-dimensional images show the distribution of EA within the pipe. EA is found to be uniformly distributed in a normal pipe. Examples of degraded pipes, due to exposure to extreme conditions, show migration of EA to the pipes' wall surfaces. NMR images of a normal pipe and two examples of damaged pipes are presented. The imaging technique and the results are discussed. © 1995 John Wiley & Sons, Inc.     

Fluorescent gallium and indium bis(thiosemicarbazonates) and their radiolabelled analogues: synthesis, structures and cellular confocal fluorescence imaging investigations

New fluorescent and biocompatible aromatic Ga(III)- and In(III)-bis(thiosemicarbazonato) complexes for dual mode optical and PET or SPECT molecular imaging have been synthesised via a synthetic method based on transmetallation reactions from Zn(II) precursors. Complexes have been fully characterised in the solid state by single crystal X-ray diffraction and in solution by spectroscopic methods (UV/Vis, fluorescence, (1)H and (13)C{(1)H} NMR). The bis(thiosemicarbazones) radiolabelled rapidly in high yields under mild conditions with (111)In (a gamma and Auger emitter for SPECT imaging and radiotherapy with t(1/2) = 2.8 d) and (68)Ga (a generator-available positron emitter for PET imaging with t(1/2) = 68 min). Cytotoxicity and biolocalisation studies using confocal fluorescence imaging and fluorescence lifetime imaging (FLIM) techniques have been used to study their in vitro activities and stabilities in HeLa and PC-3 cells to ascertain their suitability as synthetic scaffolds for future multimodality molecular imaging in cancer diagnosis and therapy. The observation that the indium complexes show certain nuclear uptake could be of relevance towards developing (111)In therapeutic agents based on Auger electron emission to induce DNA damage.     

Rheo-NMR in food science—Recent opportunities

For over 25 years, nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) techniques have been used to study materials under mechanical deformation. Collectively, these methods are referred to as Rheo-NMR. In many cases, it provides spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (such as relaxation times), or motion (such as diffusion or flow). Therefore, Rheo-NMR is complementary to conventional rheological measurements. This review will briefly summarize current capabilities and limitations of Rheo-NMR in the context of material science and food science in particular. It will report on recent advances such as the incorporation of torque sensors or the implementation of large amplitude oscillatory shear and point out future opportunities for Rheo-NMR in food science.     

笼状碳氢化合物五环[5.4.0.02，6.03，10.05，9]十一烷的密度泛函理论研究

运用密度泛函理论,在B3LYP/6-31G**水平上,对典型高能量密度笼状化合物五环[5.4.0.02,6.03,10.05,9]十一烷（PCU）进行了理论计算。基于上述水平全优化分子结构的键长、键角及二面角求得PCU分子的张力能;用Monte-Carlo方法得到化合物的理论密度;由简谐振动分析求得IR谱,计算结果与实验良好相符;基于振动分析,由统计热力学求得PCU的热力学性质;采用GIAO方法求得PCU的13C-NMR和1H-NMR谱的化学位移,计算结果与实验结果的线性相关性均大于0.99,计算结果可辅助解析PCU的NMR谱。     

Monitoring the elimination of gadolinium-based pharmaceuticals. Cloud point preconcentration and spectrophotometric determination of Gd(III)-2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminophenol in urine

An extraction methodology based on cloud point phase separation of non-ionic surfactants has been developed for the preconcentration of ppb amounts of gadolinium in urine as a prior step to its determination by an absorptiometric procedure. A method based on the formation of complexes with 2-(3,5-dichloro-2-pyridylazo)-5-dimethylaminophenol was used for the extraction of Gd(III) in the surfactant-rich phase of non-ionic surfactant polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5). The variables affecting the combined preconcentration-absorptiometric method have been evaluated and optimised. The extraction efficiency, linearity, and the limit of detection (LOD) of the method were determined. The optimised procedure was applied to determine total and free Gd(III) contents in real urine samples of patients after the NMR imaging diagnostic examination with contrast agent.     

Proton magnetic resonance imaging with para-hydrogen induced polarization

A major challenge in imaging is the detection of small amounts of molecules of interest. In the case of magnetic resonance imaging (MRI) their signals are typically concealed by the large background signal of e.g. the body. This problem can be tackled by hyperpolarization which increases the NMR signals up to several orders of magnitude. However, this strategy is limited for (1)H, the most widely used nucleus in NMR and MRI, because the enormous number of protons in the body screens the small amount of hyperpolarized ones. Here, we describe a method giving rise to high (1)H MRI contrast for hyperpolarized molecules against a large background signal. The contrast is based on the J-coupling induced rephasing of the NMR signal of molecules hyperpolarized via PHIP and it can easily be implemented in common pulse sequences. We discuss several scenarios with different or equal dephasing times T(2)* for the hyperpolarized and thermally polarized compounds and verify our approach by experiments. This method may open up unprecedented opportunities to use the standard MRI nucleus (1)H for e.g. metabolic imaging in the future.     

Nondisruptive Dissolution of Hyperpolarized 129Xe into Viscous Aqueous and Organic Liquid Crystalline Environments

Studies of hyperpolarized xenon‐129 (hp‐¹²⁹Xe) in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. Herein a device is reported that can be reliably used to dissolve hp‐¹²⁹Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes (<60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments show that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid‐crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized‐gas NMR spectroscopy.     

In situ 13C DEPT-MRI as a tool to spatially resolve chemical conversion and selectivity of a heterogeneous catalytic reaction occurring in a fixed-bed reactor

The distortionless enhancement by polarisation transfer (DEPT) nuclear magnetic resonance (NMR) technique, combined with magnetic resonance imaging (MRI), has been used to provide the first in situ spatially-resolved and quantitative measurement of chemical conversion and selectivity within a fixed-bed reactor using natural abundance 13C NMR.