超高效液相色谱串联飞行时间质谱法测定水产品中18种磺胺类化合物

采用超高效液相色谱串联飞行时间质谱(UPLC-QTOF-MS)结合QuEChERS净化处理,对淡水产品中18种磺胺类化合物进行准确的鉴定。Chromalynx XS软件将化合物的保留时间以及一级母离子精确质量数作为定性依据,筛查样品中阳性化合物,对疑似阳性化合物进行人工比对二级碎片离子信息,以进一步确证阳性化合物。本实验对草鱼、黄鳝、螃蟹3种淡水产品基质效应进行考察,基质匹配外标法定量,结果表明,在50~1000μg/kg浓度范围内,18种目标化合物线性关系良好,方法检出限为2~20μg/kg,对3种基质在200、400、800μg/kg 3个添加水平的18种磺胺类化合物进行测定,回收率在70.0~124.6%之间。     

高效液相色谱-高分辨质谱法鉴定拉萨大黄化学成分

建立了高效液相色谱-高分辨质谱法分析鉴定拉萨大黄化学成分。选用Agilent Zorbax SB-C18柱（150 mm×4.6 mm×5 μm）,以乙腈和水为流动相进行梯度洗脱,流速0.5 mL/min;采用电喷雾离子源,在正、负离子模式下对拉萨大黄提取物进行一级和多级全扫描质谱分析。综合分析化合物的色谱和质谱行为,并结合对照品、文献和数据库等相关数据鉴定化合物。在负离子模式下,鉴定出63种化合物;正离子模式下,鉴定出54种化合物。所检测到的化合物包括22种鞣质类、28种茋类、6种黄酮类、3种苯丙酸类、2种苯丁酮类和2种有机酸类,其中有53种化合物为在该药材中首次发现,且未发现蒽醌类成分。该方法快速、灵敏,不仅提高了拉萨大黄复杂基质中微量化合物的鉴定效率,同时实现了对拉萨大黄提取物中不同类型化合物的分析鉴别,为进一步阐明拉萨大黄的药效物质基础及质控标准提供了科学依据。     

香椿叶精油成分的研究（2）：香椿叶精油的GC／MS定性分析

本文介绍了香椿叶精油经ＧＣ／ＭＳ分析，共定性检出５５种化合物，其中含氧化合物３８种、碳氢化合物１５种、含氮化合物２种。     

气相色谱法分析褐煤提质低温热解气中含硫化合物的研究

采用TXS-Ⅱ硫分析仪对褐煤提质过程中的低温热解气进行含硫化合物定量分析研究,结果表明:(1)将气样通过脱硫剂脱除高浓度的H2S和COS之后再进行定量,因脱硫剂吸收有机含硫化合物,测定结果偏小;(2)制备了4种新的色谱分离柱,考查了这些色谱柱对有机含硫化合物的分离效果,最终建立了简便、准确检测低温热解气中含硫化合物的气相色谱分析方法,利用该方法分别对3种褐煤的低温热解过程中的气体进行了含硫化合物分析,为低温热解气的脱硫提供了依据.     

MassWorksTM与气相色谱-质谱联用分析洋甘菊精油成分

采用气相色谱-质谱联用(GC/MS)技术,结合MassWorks^TM质谱解析软件,对产自甘肃省永登县的洋甘菊(Chamomila recutita L.)精油成分进行分析。对两种不同极性的色谱柱进行分离比较实验,确定了适合于洋甘菊精油分离分析的色谱条件和质谱条件,解析并确定出精油中的35种化合物。MassWorks软件在低分辨率质谱上可对化合物分子质量实现精确测量,为低分辨四极杆质谱确定化合物的元素组成和解析化合物结构提供重要依据,同时也为植物精油的成分分析提供新的技术手段。     

几种席夫碱衍生物的荧光性质研究

对已合成的8种席夫碱衍生物进行了荧光性能的研究,测定了它们的荧光光谱,结果表明,只有3种化合物有明显的荧光响应。我们系统研究分析了这8个化合物结构的规律性,并运用量子化学半经验AM1方法对分子结构进行了几何优化,发现取代基、共轭链长短以及分子的共面性对此类席夫碱化合物的荧光响应均有影响,这为今后进行荧光材料的分子设计提供了依据。     

色谱—质谱峰匹配技术测定一些酒类样品中四种挥发性N—亚硝基化合物

N-亚硝基化合物是公认的强致癌物质。我们曾研究和比较了四种质谱定量方法。本文采用其中一种方法即高分辨峰匹配技术测定了一些白酒、啤酒、葡萄酒共50份样品中四种N—亚硝基化合物的含量,并对其结果进行了讨论与评价。     

γ－氯丙基三烷氧基硅烷的质谱研究

本文对合成的５种γ－氯丙基三烷氧基硅烷化合物的质谱进行了研究。根据氯同位素和硅同位素离子峰相对强度推测了离子碎片组成和这类化合物的质谱裂解规律。     

1DTOCSY在确定化合物结构中的应用

本文主要是对核磁共振一维全相关实验 (1DTOCSY)在化合物结构解析中的应用进行探讨。 1DTOCSY作为NMR中一种比较新的一维实验技术 ,为糖类等化合物的结构解析带来极大的便捷 ,具有时间短、信息清晰的特点。本文以蔗糖和乙酸戊脂为样本 ,对 1DTOCSY实验中整形脉冲的选择 ,实验参数的设置进行研究 ,并尝试建立起一种利用改变混合时间辅助完成特定化合物精细结构解析的方法。     

场电离技术在果香菊GC-TOF-MS联用分析中的应用

为了探讨场电离技术在质谱分析中应用的适用性,以芳香性植物果香菊的挥发性成分为研究对象,采用微波萃取法对果香菊的挥发性成分进行提取,利用GC-EI-TOF-MS结合GC-FI-TOF-MS技术对果香菊挥发性成分进行分析研究。果香菊的乙醇溶剂提取物经色谱进样分离,用EI电离模式鉴定了12种挥发性化合物,用FI电离模式验证了11种化合物。结果表明,场电离技术作为一种辅助手段应用于挥发性成分定性定量分析领域具有一定的适用性,该方法能补充GC-EI-TOF MS联用技术中的定性化合物信息。     

Precursor effects of martensitic transformations in Ti-based alloys studied by electron microscopy with energy filtering

Precursor effects of martensitic transformations in two well-known shape memory alloys, Ti₅₀Ni₄₈Fe₂ and Ti₅₀Pd₃₄Fe₁₆, were studied extensively by energy-filtered electron microscopy, including in-situ observations, and high-resolution electron microscopy. Energy-filtered dark-field images, where weak diffuse scattering was utilized, clearly showed the microstructure in the premartensitic state of Ti₅₀Ni₄₈Fe₂. Tiny domains observable in this state were close to spherical rather than thin and slender, and the temperature dependence of the domain-like structure was clarified by the in-situ observations. It was found that Ti₅₀Pd₃₄Fe₁₆ exhibited a domain-like structure similar to that of Ti₅₀Ni₄₈Fe₂, which was attributed to a transverse lattice displacement. High-resolution images of Ti₅₀Pd₃₄Fe₁₆ showed that a domain was coupled with other ones with different orientations of distortion, so as to reduce the total strain due to their formations. Furthermore, effects of including a fundamental reflection, in addition to the diffuse scattering, on dark-field images were discussed based on the observations and the image processing.     

异性分形表面合成方法及表面特性研究

针对异性分形表面的建模,提出了一种以二维离散傅里叶变换为基础,以名义维数D_x,D_y为驱动参数的表面合成方法——合成维数法。通过对比名义维数与采用轮廓功率谱公式和数值分析法得到的表面计算维数的关系,验证了该方法的有效性。探讨了名义维数对x,y方向轮廓能量分布以及对表面及轮廓粗糙度的影响。一方面在轮廓功率谱分析的基础上定义了轮廓累计功率比,用于描述表面轮廓的能量分布特性,不仅促进了对名义维数和轮廓能量关系的定性理解,更能定量地解释不同维数值影响下频率和轮廓能量分布的关系。另一方面以能量分析为切入点,建立了名义维数与表面及轮廓粗糙度参数间的联系,并且依据能量守恒定律,证明并揭示了轮廓粗糙度R_qx,R_qy之间以及二者与面粗糙度S_q的关系。同时得出结论,D_x或D_y值越小,低频部分能量占比越高,反之亦然,但是x,y方向轮廓总功率始终相等,并随D_x,D_y增大而增大;D_x,D_y只影响S_q,R_qx,R_qy的绝对数值,二者的增大会引起粗糙度值增加,但并不影响R_qx,R_qy的相对关系。     

An experimental study of the effect of sheet thickness and grain size on limit-strains in biaxial stretching

Effects of grain size on the limiting strains attained in biaxial stretching have been investigated using 70% Cu-30% Zn brass sheets of 1.0 and 0.5 mm thickness with regular grain structures. The limit-strains were closely related to the ratio of sheet thickness, t_o, to average grain diameter, d_o, over a range of t_o/d_o between 2 and 30. In the earlier stages of stretching, growth in the amplitude of surface roughening was independent of t_o and close to being proportional to d_oε₃ where ε₃ is thickness strain in equibiaxial stretching. The diffuse instability strain was rather insensitive to the effects of the short-range strain inhomogeneities developed during such stable extension. Surface roughening became sensitive to t_o at an applied strain ε_3c which decreased with decreasing t_o/d_o. In stretching beyond ε_3c macroscopic strain localisation became established in the form of a network of surface grooves. It is concluded that the influence of grain anisotropy on limit-strains in biaxial stretching cannot be predicted in the terms of available continuum models of defect growth. An attempt is made to identify the dominant material and geometric factors which control the onset of localised necking when grain anisotropy is the principal source of inhomogeneous straining.     

气相水二聚体自由基阳离子结构的质谱研究

水是最重要的化合物之一,在各领域发挥着重要作用。本文在常温常压下在线制备了水二聚体自由基阳离子(H₂O)₂⁺·,通过碰撞诱导解离（CID）实验,结合同位素标记法对(H₂O)₂⁺·结构进行了研究。结果表明,(H₂O)₂⁺·(m/z 36)会竞争性丢失OH·和H₂O,得到m/z 19(H₂OH⁺)和m/z 18 (H₂O⁺·),揭示(H₂O)₂⁺·(m/z 36)可能以两种不同结构存在,即H结合的非对称结构［H₂OH⁺—·OH］(A)和O—O结合的对称结构［H₂O∴OH₂］⁺(B)。此外,使用氘化水(D₂O)和富含¹⁸O的水(H₂¹⁸O)进行了同位素标记实验。(D₂O)₂⁺·(m/z 40),(H₂O·D₂O)⁺· (m/z 38)和(H₂O·H₂¹⁸O)⁺·(m/z 38)的碰撞诱导解离结果同样佐证了水二聚体自由基阳离子存在两种不同结构。这将有助于阐明与(H₂O)₂⁺·有关的生物过程和化学反应。     

A conversion method from the E system to the M system in measuring surface roughness

The relations between the surface roughness parameters measured by the envelope datum system (E system) and those measured by the mean line datum system (M system) are analysed theoretically. Experimental relations between the two systems are obtained by calculation from the surface roughness profiles of machined surfaces.

From the theoretical and experimental results it was found that the levelling depth R_P(E) in the E system is proportional to the mean arithmetic deviation R_a(M) in the M system and the ratio R_P(E)/R_a(M) increases with an increase in the tip radius of the skid. The mean roughness value R_a(E) in the E system is larger than R_a(M) by 10% at its maximum.     

Development of an optimal protocol for the ultrastructural examination of skin by transmission electron microscopy

The intercellular lipid bilayers of the stratum corneum provide the permeability barrier of the skin. To perform an electron microscopical examination of the ultrastructure of these bilayers, ruthenium tetroxide fixation is required. In this study an optimal fixation protocol was developed and selected upon comparing seven different fixation procedures, using glutaraldehyde (GA) and the postfixatives ruthenium red, osmium tetroxide (OsO₄) and ruthenium tetroxide (RuO₄) in combination with potassium ferrocyanide (K₄Fe(CN)₆) and potassium ferricyanide (K₃Fe(CN)₆). Instead of fixing skin with either OsO₄ or RuO₄, these two fixatives were combined in one protocol. In addition, the use of RuRed was introduced and the influence of both K₄Fe(CN)₆ and K₃Fe(CN)₆ in combination with RuO₄ were examined. Furthermore, we compared two dehydration solvents, methanol and acetone.
The most satisfying results were obtained when the skin was prefixed in GA and postfixed in OsO₄ and RuO₄ with K₃Fe(CN)₆, i.e. with Fe in its highest oxidation state (Fe³⁺). No differences were observed between dehydration in methanol and acetone.     

Accurate structure determinations of very small (4–20 nm) areas, using refinement of dynamic electron diffraction data

It is shown that accurate structure refinements are possible from electron diffraction data obtained using areas 4–20 nm in diameter and 4–20 nm thick. To obtain accurate atomic positions it is essential to take the dynamic diffraction fully into account, for which new software was developed. Examples (La₃Ni₂B₂N₃, Ba₂Ca₃Cu₅O_10+δ and Ce₅Cu₁₉P₁₂) are given of the structure refinements of known and unknown structures with R -values in the range 2–6%. The procedure reported in this paper opens the way to structure determination of particles in many materials of industrial and scientific interest which cannot be solved by conventional structure determination (e.g. because of small size, heavily twinned materials or small fractions in polyphase materials).