Carbon-13 Nuclear Magnetic Resonance Spectra of Some Protoilludane Sesquiterpenoid Aromatic Esters from Armillaria mellea (Vahl.ex Fr.) Quel.

The carbon-13 nuclear magnetic resonance spectra of seventeen protoilludane ses- quiterpenoid aromatic esters from the artificially cultured mycelium of Armillaria mellea (Vahl.ex Fr.) Quel.have been analysed and assigned.All the ^(11)CNMR signals of the model compounds melleolide 5 and compounds 8,10,11,13,14,15,and 16 can be assigned on the basis of the multiplicity of the sig- nals in the off-resonance decoupled spectra or INEPT spectra.^(11)C-~1H COSY and long-range ^(13)C-~1H COSY.The assignments of the ^(13)CNMR spectra of other protoilludane sesquiterpenoid aromatic esters were completed by comparison with the model compounds as well as the electronic effects of substi- tuted group on the molecules.The present results indicate that ^(11)CNMR spectroscopy provides an ef- fective method for characterizing the protoilludane sesquiterpenoid aromatic esters.

Application of nuclear magnetic resonance technology to carbon capture,utilization and storage:A review

Carbon capture,utilization and storage (CCUS) is considered as a very important technology for mitigating global climate change.Carbon dioxide (CO2) injected into an underground reservoir will induce changes in its physical properties and the migration of CO2 will be affected by many factors.Accurately understanding these changes and migration characteristics of CO2 is crucial for selecting a CCUS project site,estimating storage capacity and ensuring storage security.In this paper,the basic principles of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) technologies are briefly introduced in the context of laboratory experiments related to CCUS.The types of NMR apparatus,experimental samples and testing approaches applied worldwide are discussed and analyzed.Then two typical NMR core analysis systems used in CCUS field and a self-developed high-pressure,low-field NMR rock core flooding experimental system are compared.Finally,a summary of the current deficiencies related to NMR applied to CCUS field is given and future research plans are proposed.

Investigation of reinforcement of the modified carbon black from wasted tires by nuclear magnetic resonance

Pyrolysis has the potential of transforming waste into recyclable products. Pyrolytic carbon black (PCB) is one of the most important products from the pyrolysis of used tires. Techniques for surface modifications of PCB have been developed. One of the most significant applications for modified PCB is to reinforce the rubber matrix to obtain high added values. The transverse relaxation and the chain dynamics of vulcanized rubber networks with PCB and modified PCB were studied and compared with those of the commercial carbon blacks using selective 1H transverse relaxation (T2) experiments and dipolar correlation effect (DCE) experiments on the stimulated echo. Demineralization and coupling agent modification not only intensified the interactions between the modified PCB and the neighboring polyisoprene chains, but also increased the chemical cross-link density of the vulcanized rubber with modified PCB. The mechanical testing of the rubbers with different kinds of carbon blacks showed that the maximum strain of the rubber with modified PCB was improved greatly. The mechanical testing results confirmed the conclusion obtained by nuclear magnetic resonance (NMR). PCB modified by the demineralization and NDZ-105 titanate coupling agent could be used to replace the commercial semi-reinforcing carbon black.

Porosity and Pore Size Distribution Measurement of Cement/Carbon Nanofiber Composites by ~1H Low Field Nuclear Magnetic Resonance

The dispersion effect of carbon nanofibers （CNFs） in aqueous solution and the mechanical properties, porosity, pore size distribution and microstructure of CNFs reinforced cement-based composites were investigated in this paper. To achieve effective dispersion of CNFs, a method utilizing ultrasonic processing and a commercially surfactant were employed. CNFs were incorporated to cementitious materials with the addition of 0.1 wt% and 0.2 wt% of cement with a water/cement ratio of 0.35. The mechanical properties of CNFs/ cement composites were analyzed, the porosity and pore size distribution were characterized by ^1H low field nuclear magnetic resonance （NMR）, and the microstructure was observed by scanning electron microscopy （SEM）. The results indicate that the optimum concentration ratio of MC to CNFs is 2：1 for dispersing in aqueous solution. Moreover, in the field of mechanical properties, CNFs can improve the flexural strength and compressive strength. The increased mechanical properties and the decreased porosity of the matrices correspond to the increasing CNFs content and CNFs act as bridges and networks across cracks and voids.

Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy

Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in coal.MS(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and analyzed.The results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring decreases.The heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and tight.The stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy EN.Key Stretching Energy The size of EB determines how tight the structure is.The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.

^13C-NMR在抗冲共聚聚丙烯序列结构研究中的应用

论述了^13C-NMR在抗冲共聚聚丙烯序列结构研究中的进展。介绍了抗冲共聚聚丙烯N脉谱图及谱图归属和单元组的分布、组成及数均序列长度的计算方法。研究结果表明抗冲共聚聚丙烯主要是由乙丙无规共聚物、乙丙可结晶共聚物（富含乙烯或丙烯均可能存在）和聚丙烯均聚物组成。

氮杂噢哢中苯环^(13)C-NMR图谱分析

用合成出的氮杂噢哢所测定的13C-NMR图谱与对应的噢哢类化合物的相关文献报道、文献报道经验计算结果以及计算机分析软件模拟计算结果相对照,分析比较苯环上对应各碳在图谱中的化学位移,确证化合物结构,研究其13C-NMR图谱出峰顺序和规律,并丰富相关化合物的波谱数据。

1-[5-(3-吡啶)-四唑-2-乙酰基]-4-芳基氨基硫脲及3-[5-(3-吡啶)-四唑-2-亚甲基]-4-芳基-1,2,4-三唑-5-硫酮等化合物的^(13)C-NMR 的研究

本文测定1-[5-(3-吡啶)-四唑-2-乙酰基]-4-芳基氨基硫脲及3-[5-(3-吡啶)-四唑-2-亚甲基]-4-芳基-1,2,4-三唑-5-硫酮等六种化合物的^(13)C-NMR 谱.各种^(13)C-NMR 化学位移,根据取代基效应,讯号强度以及同模型化合物化学位移对照而确认其归属.

An atomic electronegative distance vector and carbon-13 nuclear magnetic resonance chemical shifts of alcohols and alkanes

A novel atomic electronegative distance vector (AEDV) has been developed to express the chemical environment of various chemically equivalent carbon atoms in alcohols and alkanes. Combining AEDV and γ parameter, four five-parameter linear relationship equations of chemical shift for four types of carbon atom are created by using multiple linear regression. Correlation coefficients are R = 0.9887, 0.9972, 0.9918 and 0.9968 end roots of mean square error are RMS = 0.906, 0. 821, 1.091 and 1.091 of four types of carbons, i.e., type 1, 2, 3, and 4 for primary, secondary, tertiary, and quaternary carbons, respectively. The stability and prediction capacity for external samples of four models have been tested by cross-validation.

Investigation of carbon-13 nuclear magnetic resonance spectra-structure correlation based on novel atomic distance-edge (ADE) vector

A set of novel graph-theoretical parameters, called the atomic distance-edge (ADE) vector, was developed. Baaed on the connecting C-C bond number between central carbon atom and the other ones, various carbon atoms of alkanes were classified as four types, i.e., type 1, 2, 3 and 4 for primary, secondary, ternary and quaternary carbon, respectively; and then four regression equations were obtained to link carbon-13 chemical shift (CS) of each type of atoms. Furthermore, these regression models were used to predict the carbon-13 nuclear magnetic resonance spectra of alkanes and it was found that the estimated CS were in agreement with the experimental results.

Simulation of ^(13)C NMR chemical shifts of carbinol carbon atoms using quantitative structure-spectrum relationships

A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.

用^(13)C-NMR表征高乙烯含量乙烯-丙烯无规共聚物的结构与性能

采用淤浆聚合法,使用3种聚丙烯催化剂制备了高乙烯含量乙烯-丙烯无规共聚物,并采用核磁共振碳谱对共聚物结构和性能进行了表征。结果表明:在相同聚合条件下,使用二醇酯化合物作为内给电子体的ND催化剂同已商业化的两种Ziegler-Natta催化剂CAT1和CAT2聚合得到的乙烯-丙烯无规共聚物中的乙烯摩尔分数接近,为75%~78%;使用ND催化剂聚合得到的乙烯-丙烯无规共聚物链段中乙烯-丙烯单元序列分布更均匀;使用ND催化剂聚合得到的乙烯-丙烯无规共聚物中橡胶相相对含量高于采用CAT1和CAT2催化剂。

用^(13)C-NMR法研究SBR的序列结构 Ⅰ.不饱和碳区谱峰的归属

在缺乏苯乙烯单元对主链烯碳化学位移影响的经验参数时,借助乙烯基的参数预测SBR主链烯碳的峰位,对6种乳聚SBR和1种溶聚SBR样品主链烯碳的13组^(13)C-NMR谱带(Ⅱ_3至Ⅱ_(15))进行了归属。在本实验条件下,观察到17组不饱和碳区吸收峰。基于对谱峰的归属,用概率统计法计算了有代表性的3种胶样的主链烯碳谱峰的相对强度,其计算值与实验值相当吻合,说明运用经验参数估算法,对谱峰进行的归属是合理的。

^(13)C NMR分析食用油甘油酯组成的方法研究

研究采用核磁共振碳谱法(^(13)C NMR),首先识别食用油脂中甘油一酯(MG)、甘油二酯(DG)、甘油三酯(TG)及游离脂肪酸(FFA)等组分的特征峰,然后确定特征峰响应值与组分含量的关系,最后建立了食用油脂中甘油酯组成的核磁共振碳谱分析方法。实验结果表明,样品量为200 mg食用油甘油酯,溶剂为0.5 mL氘代氯仿,^(13)CNMR谱采集条件为脉冲序列zgpg30,扫描次数(NS)为100,脉冲宽度(P1)为30μs,能够快速的测定甘油酯样品中MG、DG、TG和FFA的相对质量分数,且所测定结果与柱层析分离法测定的结果没有显著差异。该方法对响应值最低的游离脂肪酸的检出限可低至1.35%,定量限可低至4.45%。

不同溶剂预处理煤在ScCO_(2)作用下的谱学差异及其机制

为了探究溶剂预处理后超临界二氧化碳(ScCO_(2))对煤化学结构的影响,以长治霍尔辛赫贫煤为研究对象,分别用四氢呋喃(THF)、盐酸(HCI)和氢氟酸(HF)对煤样进行预处理,采用傅里叶红外光谱(FTIR)、固体核磁共振(^(13)C-NMR)和X射线衍射(XRD)测试,探讨了ScCO_(2)对预处理煤的化学组成和结构的影响机理。研究表明:①FITR分峰拟合谱图实验曲线基本一致,而各官能团吸收峰位置及峰强度仍出现一定的偏差,酸(HCI、HF)预处理后部分波段脂肪族峰位消失。两类酸预处理顺序不同,对煤中含氧官能团、脂肪结构及芳烃结构作用效果也不相同。HF-HCI处理后芳烃C=C结构和含氧官能团峰强度均增强,而HCI-HF处理后芳烃C=C结构强度减弱,含氧官能团结构峰强度变化不明显。THF预处理后煤样芳烃C=C结构峰强度增强,含氧官能团结构峰强度降低。总体芳烃C=C结构峰强度远大于脂肪族结构和含氧官能团结构的峰强度。②^(13)C-NMR谱中主要官能团谱峰的化学位移出现了一定程度的偏移,芳香碳f_(a)^(B)化学位移向增大的方向偏移。大分子结构参数中,芳香碳含量远大于脂肪碳含量,说明煤大分子结构中芳香碳占主要组成部分。③XRD谱中002峰与101峰衍射强度明显增大,芳香微晶层网面间距d_(002)呈现升高趋势,说明THF、酸(HF、HCI)处理和ScCO_(2)对煤大分子结构产生了一定程度的改造作用,使煤的大分子网络结构变得疏松,进而使微晶结构参数d_(002)整体增大。研究认为,溶剂作用后煤的谱学特征变化不仅与溶剂性质有关,还与无机酸处理顺序有关,由此使得官能团组成和大分子结构不同程度改变,进而影响ScCO_(2)对预处理煤的萃取效果。

X射线光电子能谱与^(13)C核磁共振在生物质碳表征中的应用

近年来,生物质碳(biochar)作为新型吸附剂被广泛研究。但由于制备biochar的生物质原料和热解温度的不同,使biochar的结构和组成存在差异,从而影响其对污染物的吸附。目前关于biochar的结构和组成的研究还不够全面。因此,结合了能谱与光谱分析的手段,对biochar的结构和组成进行了深入的分析。选取木质类(柳树枝条)和草类(水稻秸秆)作为原料,分别在不同热解温度(300,450和600℃)下制得biochars,并对biochars样品进行元素分析、X射线光电子能谱分析(XPS)和固态13 C核磁共振(13 C NMR)研究,以阐明不同热解温度和生物质来源的biochars的结构和组成。结果显示:biochar的H/C,O/C和(O+N)/C的比值随着热解温度的升高而降低;草类biochar比木质类biochar具有更高的灰分含量和表面极性;木质类biochar的矿物主要分布在样品颗粒内部,其表面被有机质覆盖,而草类biochar部分矿物暴露在样品颗粒表面;13 C NMR显示低温制得的biochar主要由芳香碳、脂肪碳、羧基和羰基碳组成,高温制得的biochar主要由芳香碳组成,且低温制得biochars中,木质类biochars比草类biochars含有更高的木质素的残留碳结构,这是由于木质类biochars原材料中含有更高的木质素。

^(13)C NMR定量分析一乙醇胺(MEA)与CO_2的吸收和解吸特性

13C NMR是一种有效的测定有机胺与CO2反应过程中离子浓度变化的检测手段。本文采用13C NMR分析了一乙醇胺(MEA)吸收与解吸CO2过程,吸收与解吸实验温度分别在313K和393K下进行。结果表明,吸收CO2过程中生成了MEA氨基甲酸盐、质子胺MEAH+与HCO3-/CO32-,并且CO2与MEA反应时先生成MEA氨基甲酸盐,当溶液吸收的CO2担载量达到0.455molCO2/mol胺时,才产生HCO3-/CO32-离子。在MEA吸收CO2过程中,MEA氨基甲酸盐的摩尔分数先增加后减少。在解吸过程中,MEA氨基甲酸盐的摩尔分数同样先增加后减少。HCO3-/CO32-在解吸过程中很容易就能被解吸,而生成的MEA氨基甲酸盐中大约有75%在解吸过程中并没有被解吸。

基于固态^(13)C核磁共振波谱研究植物残体分解和转化机制的进展

植物残体在土壤中的分解和转化影响了其养分归还和有机质形成过程。由于缺乏高分辨率的分析方法,对不同气候、植被和土壤类型条件下植物残体在分解过程中化学结构组成的演变特征和机制仍不清楚。核磁共振波谱技术在解析自然有机物化学组成方面具有独特的优势,本文综述了基于固态^(13)C核磁共振波谱(solid-state ^(13)C-NMR spectroscopy)技术评价植物残体的基质质量、解析植物残体的分解速率及其官能团组成的变化特征、揭示土壤腐殖质特性等方面的主要进展。未来针对植物残体分解和有机质形成机制的研究,应该结合稳定性同位素质谱和扫描电镜分析方法,综合分析植物残体中的有机化合物组成和物理结构;从多时空尺度揭示不同类型植物残体中有机碳官能团的降解路径;结合高通量测序和基因芯片分析方法,深入研究土壤微生物群落与植物残体化学结构的协同演变机制,提出不同气候–土壤–植被类型区促进土壤有机质形成的调控措施。

脂肪胺类化合物的^(13)C核磁共振波谱模拟

对脂肪胺类化合物的1 3C核磁共振波谱进行了模拟 ,所用方法为数学模型法。为此 ,提取了共振碳原子所处化学环境的拓扑特征、几何特征及电子特征。运用变量最优子集回归法对变量进行了选择 ,用多元回归法构造了数学模型 ,得到了比较满意的预测结果。

俾路支褐煤有机结构特征及大分子模型构建

以巴基斯坦俾路支褐煤(BL)为研究对象,由元素分析得出BL化学式为C_(167)H_(130)O_(53)N_(2)S。经X射线光电子能谱(XPS)分析BL有机结构中氧、氮和硫元素存在形式。利用傅里叶变换红外光谱(FT-IR)研究BL有机结构中主要官能团特征,-CH和-CH^(2)为BL脂肪族结构中主要官能团。BL中苯环主要取代形式为三取代和四取代。运用核磁共振光谱(^(13)C-NMR)探究BL有机结构碳骨架结构。BL分子结构中,芳香桥碳与周碳之比X_(BP)为0.21,碳主要由芳香碳和脂肪碳2部分构成,其中脂肪碳质量分数53.23%,芳香碳占比41.93%。芳香结构以苯环和萘环为主,氧主要以羧基、羰基、醚氧和酚羟基形式存在,而氮主要以吡咯氮形式存在,硫主要为噻吩。建立BL二维分子结构模型,通过Materials Studio对其进行加氢饱和,构建BL分子模型三维立体结构,进一步优化所得分子模型,空间效果显著,得到能量最低的BL三维结构模型,发现范德华能是BL分子结构稳定的关键因素。通过计算得到的BL模型结构^(13)C NMR谱图与试验所测谱图基本一致,验证了所构建BL结构模型的合理性。