含N-非取代葡糖胺残基肝素四糖的制备与表征

生物体内含有N-非取代葡糖胺残基（GlcNH₃⁺）结构的硫酸类肝素（HS）具有重要的生物和病理生理学功能。但这种HS在生物体内的含量较少、获得困难,而采用化学方法制备与生物体内结构相似的这种寡糖,有助于研究HS在生物体内的功能作用。本实验以高硫的肝素四糖为原料,用部分脱N位硫酸根的方法,制备了含1个和2个GlcNH₃⁺的肝素四糖,并采用液相色谱-离子阱-飞行时间质谱（LC/MS-IT-TOF）法对其进行结构检测。通过分析（EIC）-MS和MS²提取离子流图发现,含不同GlcNH₃⁺数目的肝素四糖具有不同的裂解规律,含GlcNH₃⁺数目越多,生成的碎片离子越多,这为MS方法进一步鉴定和定量测定含GlcNH₃⁺结构的寡糖奠定了基础。     

碱性橙21、22和罗丹明B的多级质谱裂解规律探析

采用电喷雾离子阱多级质谱技术（ESI-MSⁿ）在正离子模式下（ESI+）对食品中常见的几种非法添加工业染料碱性橙21、22和罗丹明B进行裂解规律探析。分析了这3种染料从分子离子出发的多级质谱裂解碎片,发现此类化合物容易先失去Cl^-,形成N⁺离子;在电离源的轰击下,容易失去·CH₃和·CH₂CH₃;并且探析了碱性橙21、22和罗丹明B的多级质谱裂解规律。该质谱裂解规律有助于推断碱性工业染料及其类似物的结构特点和裂解规律,为此类化合物的快速鉴定提供依据。     

通关藤中甾体化合物的电喷雾质谱裂解规律研究

利用电喷雾串联质谱(ESI-MSn)研究从云南产通关藤(Marsdeniatenacissi ma(Roxb.)Wight et Arn)中分离纯化得到的19种甾体化合物的裂解规律,分析了它们从分子离子出发的多级质谱的裂解碎片,主要报道了tenacigenoside B,tenacigenoside G,tenacigenoside H在ESI正离子模式下[M+Na]+的裂解途径和碎片离子峰,结合其他16种化合物的裂解实验,说明这些甾体化合物主要丢失C-11和C-12位上的取代基,其次是糖苷上糖顺序断裂。这有助于依据此类化合物结构特点和裂解规律来推断其结构,为此类化合物的快速鉴定提供依据。n     

肝素/硫酸乙酰肝素四糖同分异构体的制备与表征

肝素/硫酸乙酰肝素（Hep/HS）寡糖结构多样，且与生物学、病理学功能息息相关，表征这些结构对解析它们的功能具有重要意义。本实验以市售猪肠肝素钠为原料，制备了9种肝素四糖，并用二糖组分分析方法结合反相离子对试剂色谱-串联离子阱飞行时间质谱(IPRP-LC/IT-TOF MS)进行结构解析。结果表明：9种肝素四糖中有两组同分异构体，且含己胺离子对试剂的RP-LC/MS能够成功分离肝素寡糖及其同分异构体；采用LC-MS/MS方法可以鉴定其中一组同分异构体的结构。该方法可为HS/Hep寡糖的研究提供标准品，并为解析HS/Hep同分异构体结构提供一种简单有效的方法，进而为更好地理解生物体内HS/Hep结构和生理生化功能的关系提供帮助。     

羰基化合物腙衍生物的高分辨质谱碎裂行为

采用高效液相色谱-电喷雾-四极杆/静电场轨道阱高分辨质谱法（HPLC-ESI-Q-Orbitrap MS）分析25种醛酮类羰基化合物（CC）与2,4-二硝基苯肼（DNPH）衍生后生成的腙衍生物的质谱裂解规律。以平行反应监测（PRM）方式获得母离子和碎片离子信息,并建立质谱库;以全扫描/数据依赖二级子离子扫描 (Full MS/dd-MS²) 方式获得的母离子峰面积进行定量,以保留时间、母离子和子离子精确质量数进行定性筛查。在ESI^-模式下,CC-DNPH衍生物形成［M-H］^-准分子离子,并进一步碎裂形成m/z 76、122、181、163、152等碎片离子,根据碎片离子精确质量数确定化合物结构并解析质谱裂解规律,同时比较了饱和脂肪醛、不饱和脂肪醛、芳香醛、酮等化合物的裂解特征。应用本方法筛查分析天津市5个环境空气样品,其中24种现有标物对应目标物为阳性,平均浓度在0.006~4.45 μg/m³之间,根据裂解规律、母离子和子离子精确质量,扩展筛查出其他12种可能存在的羰基化合物,其半定量浓度在0.007~4.18 μg/m³之间。本研究可为小分子化合物的质谱裂解规律研究提供借鉴。     

N-烷基酰胺类衍生物的质谱裂解机制研究

以阿纳其根中的N-烷基类化合物（NAAs）为先导化合物，以对羟基苯乙胺和系列脂肪酸为原料，HATU为缩合剂，合成了N-烷基酰胺酯类（A）、N-烷基酰胺类（B）两类共20种新化合物，并用UPLC-Q-TOF-MS技术获取裂解数据，探讨其质谱裂解规律。在ESI⁺模式下，这20种化合物均易形成［M+H］⁺准分子离子。A类化合物首先发生羰基α断裂，即C-O键断裂，再发生N-位α裂解，分别形成4-羟基苯乙胺离子［M+H］⁺（m/z 138.091 2）和4-羟基苯乙基离子（m/z 121.063 0）；B类化合物仅发生N-位α裂解。通过多巴速率氧化法评价了NAAs衍生物的体外酪氨酸激活活性，结果表明，该类化合物具有较好的激活体外酪氨酸酶活性，其中H 2优于阳性对照药8-MOP。该研究可为NAAs类化合物的结构分析及开发应用提供参考依据。     

麻痹性贝毒素电喷雾质谱负离子模式分析特征

利用多级质谱技术对8种常见麻痹性贝毒素（GTX1, GTX 4, GTX2, GTX 3, dcGTX2, dcGTX3, C1和C2）在电喷雾质谱负离子模式下的分析特征进行研究。结果表明:8种目标化合物在一级质谱分析过程中均易失去1个H,形成准分子离子[M-H]^-峰（基峰）;在二级质谱分析过程中,各化合物的母离子（[M-H]^-）主要通过丢失-H₂O和-NHCO等中性碎片,形成稳定的特征子离子峰,并且同分异构体的二级质谱图有差异,可为含硫麻痹性贝毒素的二级质谱定性、定量分析提供依据。此外,对各目标化合物二级质谱的主要碎片峰进行三级质谱分析,对产生的主要特征碎片峰进行归属,并推测裂解途径。本研究可为电喷雾质谱在负离子模式下检测含硫麻痹性贝毒素提供参考和依据。     

（2,4-二甲氧基苯基）烯丙基丙二酸二乙酯异构体的GC/MS研究

为了研究钯催化的2,4-二甲氧基苯甲酸与烯丙基丙二酸二乙酯的脱羧Heck反应的产物结构,建立了（2,4-二甲氧基苯基）烯丙基丙二酸二乙酯同分异构体的分离与鉴定的气相色谱-离子阱质谱方法。首先通过脱羧Heck反应制得（2,4-二甲氧基苯基）烯丙基丙二酸二乙酯异构体混合物,然后利用GC/MS联用技术对混合物进行分析,得到各组分的EI和CI全扫描模式质谱信息。通过对照各组分的分子离子峰确定互为异构体的组分,再对异构体组分采用MS/MS模式获取各自的裂解碎片。通过分析异构体的不同的裂解碎片,讨论质谱裂解方式,从而确定异构体的结构。该方法省时、经济、高效,可为此类化合物的分析与鉴别提供参考。     

基于LTQ-Orbitrap高分辨质谱的骆驼蓬子中生物碱类成分鉴定及裂解途径分析

采用高效液相色谱-质谱（HPLC-MSⁿ）法分析骆驼蓬子甲醇提取物中的生物碱类成分。在正离子模式下,采用C18色谱柱,以乙腈0.5%氨水溶液为流动相进行梯度洗脱,LTQ-Orbitrap线性离子阱高分辨质谱解析多级质谱数据,并对成分进行定性分析。结果表明,从骆驼蓬子甲醇提取物中共鉴定出20种生物碱类成分,其中鸭嘴花酮碱葡萄糖苷、3-羟基-去氢骆驼蓬碱和鸭嘴花碱糖苷为首次从骆驼蓬子中鉴定得到;同时对路因碱、四氢哈尔明、鸭嘴花碱糖苷的质谱裂解途径进行分析,推测出一系列去氢骆驼蓬碱衍生物的裂解规律。该方法可为骆驼蓬子的化学成分和质量控制提供理论基础,也可为类似结构化合物的质谱裂解规律研究提供方法参考。     

UHPLC-LTQ-Orbitrap分析硫磺熏蒸麦冬中高异黄酮硫酸酯和亚硫酸酯

为了阐明麦冬中高异黄酮类成分在硫磺熏蒸过程中的变化,采用UHPLC-LTQ-Orbitrap高分辨质谱法,利用Waters HSS T3UPLC色谱柱(2.1mm×100mm×1.7μm),以0.1%甲酸水(A)-乙腈/甲醇(3∶1,V/V)(B)为流动相进行梯度洗脱,并采用ESI离子源负离子扫描模式对样品进行分析。根据得到的高分辨质谱数据及多级质谱裂解碎片离子,从硫磺熏蒸麦冬药材中筛选了41个高异黄酮含硫衍生物,并对其中的31个化合物进行了结构鉴定,包括16个硫酸酯和15个亚硫酸酯。结果表明,麦冬高异黄酮在硫磺熏蒸过程中除了发生硫酸酯化和亚硫酸酯化外,其自身母核结构也可能发生改变。本研究阐明了麦冬中高异黄酮在硫磺熏蒸过程中的转变情况,可以为硫磺熏蒸麦冬药材中化学成分的体内ADME过程、药效学以及毒理学等研究奠定基础。     

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基于远红外光谱技术的毒品光谱分析

傅里叶变换红外光谱仪(FTIR)可以获取物质的远红外光谱,并根据其指纹特征光谱对未知样品进行鉴定。在真空条件下运用FTIR测试了可卡因、盐酸氯胺酮、大麻酚、海洛因以及吗啡等五种毒品标准品在远红外波段(30~350cm-1)的吸收光谱并对部分吸收峰进行了分析。实验结果表明,这五种毒品标准品在远红外波段内均有明显的特征吸收峰。研究结果可为建立毒品的远红外光谱数据库和实现毒品快速鉴别提供参考。     

电感耦合等离子体质谱法测定高纯氧化镧中铈含量

采用电感耦合等离子体质谱法(ICP-MS)测定了高纯La₂O₃中的Ce含量。选择同位素¹⁴⁰Ce和¹⁴²Ce进行测定,通过建立校正方程,分别考察了不同Nd含量的La₂O₃样品中¹⁴⁰Ce和¹⁴²Ce的质谱干扰情况和校正效果。结果表明,在Nd含量较高的情况下,¹⁴²Ce的质谱干扰校正效果较差,回收率为-322%,RSD为173%,而¹⁴⁰Ce的质谱干扰校正效果较好。因此,建立了Nd含量较高的La₂O₃中Ce含量的测定方法,¹⁴⁰Ce的检出限为1.5 μg/g,相对标准偏差（RSD）在0.72%~1.6%之间,回收率为104%~106%。     

Tribochemical Reactions and Lubricating Effects of Fluorinated Methanes for Al2O3 Ceramic

It has been found that CF₃CH₂F (HFC-134a) gas is an effective lubricant for several ceramics because of the formation of fluorine-containing tribochemical products. To understand the influence of the molecular structure of fluorine-containing gases on the lubricating characteristics, the lubricating effects and tribochemical reactions of some fluorinated methanes for Al₂O₃ ceramic were studied. X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) were used to identify the chemical structure of tribochemical products. It was found that the friction and wear of Al₂O₃ ceramic were dependent on the molecular structure of the reacting fluorocarbon gases. The lowest friction was obtained in CH₂F₂. CHF₃ showed the best anti-wear effect. The results of surface analyses indicate that greater amounts of tribochemical products are produced when Al₂O₃ rubs in CH₂F₂ than in CF₄ and CHF₃ gases. C–C/C–H/carbon and AlF₃, which are mainly formed on the sliding surface in CH₂F₂, are responsible for the low friction. The mechanism of tribochemical reactions of the different environmental molecules on the nascent surface of Al₂O₃ was also discussed.     

反相液相色谱-电喷雾-离子阱-飞行时间质谱法定量分析N-非取代肝素/硫酸乙酰肝素

肝素和硫酸乙酰肝素由重复的二糖单元组成,其组分和结构与重要的生物病理、生理作用息息相关。这些二糖单元包括含量较高的N-硫酸化葡萄糖胺、N-乙酰化葡萄糖胺和含量较低的N-非取代葡萄糖胺残基。本研究采用2-氨基吖啶酮标记二糖,结合反相液相色谱-电喷雾-离子阱-飞行时间质谱法(RP-LC-ESI-IT-TOF MS)分析肝素/硫酸乙酰肝素中N-非取代二糖。通过优化检测条件,实现了12种肝素/硫酸乙酰肝素二糖的基线分离,并采用外标法相对定量分析各二糖组分。该方法适用于分析含有N-非取代二糖的肝素衍生物,可为进一步研究N-非取代葡萄糖胺的结构与功能提供检测方法,有助于更好地理解N-非取代葡萄糖胺残基在人类健康与疾病管理中的重要作用。     

Frictional Behavior of Polyurethane Modified by Carbon Coatings Synthesized in Dual-Frequency Plasma

A method for changing the surface properties of polymeric materials is by plasma treatment and, in particular, the modification by carbon coatings synthesized using plasma techniques. This article presents the tribological properties of carbon coatings produced on polyurethane substrates by a dual-frequency plasma technique. The analyses were made in terms of placement of the samples in the reactor and the number of modification steps. The samples were characterized by atomic force microscopy and friction tests, which were performed using a ball-on-disc tribometer. The chemical structure of the produced coatings was analyzed with the use of Raman spectroscopy. The obtained results show that the best tribological properties were characteristic of carbon coatings produced on samples placed onto the water-cooled electrode without preliminary ion etching in an argon atmosphere. The modifications decreased the coefficient of friction from 1.2, characteristic of unmodified polyurethane, to a value of about 0.38. The wear rate was reduced from 16.8 × 10^?5 to a value of 4 × 10^?9 mm³/Nm. Based on analysis of the wear tracks it was determined that for the proposed combination of a ZrO₂ ball versus a polyurethane disc modified with a diamond-like carbon (DLC) layer the dominant mechanism of wear is friction; however, in extreme cases, when the DLC coating is worn out, characteristic debris can be observed.     

Stress distribution in a linear hardening annular disk of variable thickness subjected to external pressure

The subject of investigation is a linear hardening annular disk of variable thickness subjected to external pressure. The variation of thickness is considered for two different cases: (1) h = h_o (1 − tr)^k and (2) h = h_o (1 − tr^k), where h₀, t and k are real constants. The analysis is based on Tresca's yield condition and its associated flow rule. The governing differential equations are presented in terms of radial displacement. Exact elastic—plastic solutions are obtained in terms of hypergeometric functions for the radial displacement and stress distributions. Numerical results showing the influence of the thickness variation on the stress distribution for different values of the hardening parameter are presented graphically. It can be seen from the present analysis that the thickness variation influences the radial stress and displacement distributions significantly. The present investigation may provide useful information for structural designers and engineers working in these scopes.     

Tribo-oxidation of Self-mated Ti3SiC2 at Elevated Temperatures and Low Speed

The tribological behavior of self-mated Ti₃SiC₂ is investigated from ambient temperature to 800?°C at a sliding speed of 0.01?m/s in air. The results show that at the temperatures lower than 300?°C, friction coefficient and wear rates are as high as 0.95 and 10^?3?mm³/N?m, respectively. With the temperature increasing to 600?°C, both the friction coefficient and wear rates show consecutive decrease. At 700 and 800?°C, friction coefficient and wear rates are 0.5 and 10^?6 mm³/N?m, respectively. According to the wear mechanism, the tribological behavior of Ti₃SiC₂ can be divided into three regimes: mechanical wear-dominated regime from ambient temperature to 300?°C characterized by pullout of grains; mixed wear regime (mechanical wear and oxidation wear) from 400 to 600?°C; and tribo-oxidation-dominated wear regime above 700?°C. The tribo-oxides on the worn surfaces involve oxides of Si and Ti. And, species transformation occurs to these two oxides with the increasing temperature. In the competition oxidation of elements Ti and Si, Si is preferably oxidized because of its high active position in the crystal structure. Additionally, plastic flow is another notable characteristic for the tribological behavior of self-mated Ti₃SiC₂.     

Novel interactions of perlecan: unraveling perlecan's role in angiogenesis

Perlecan, a highly conserved and ubiquitous basement membrane heparan sulfate proteoglycan, is essential for life, inasmuch as its absence results in embryonic lethality in mice and C. elegans, and neonatal lethality in humans. Perlecan plays an essential role in vasculogenesis and chondrogenesis, as well as in pathological states where these processes are maladapted. Although a large body of evidence supports a pro-angiogenic role for perlecan, recent findings suggests that portions of the perlecan protein core can be antiangiogenic, requiring a further evaluation of the functioning of this complex molecule. This review is focused on the genetics of mammalian and nonmammalian perlecan, the elucidation of its novel interacting partners and its role in angiogenesis. By more fully understanding perlecan's functioning in angiogenesis, we may gain invaluable insight that could lead to therapeutic interventions in cancer and other pathologic states.