扫描电镜使用的石油地质样品制备方法

样品制备简单是扫描电镜的最大特点之一,然而,在多年的实践中,我们感到样品的预处理、样品的上桩粘接技术、非导电样品的镀膜方法和镀膜层厚度的控制都直接影响到样品的分析结果和图象质量。本文主要就显微形貌分析和微区成份定性分析的样品探讨石油地质样品制备技术。     

高压结晶PA1010/SWNT纳米复合材料的热性能及形貌特征

采用六面顶压机制备了尼龙1010(PA1010)/单壁碳纳米管(SWNT)复合材料在350℃、不同压力下处理30min后的高压结晶样品,通过DSC、TGA、SEM、TEM等手段研究了高压结晶样品的结晶行为、热稳定性以及形貌特征。研究结果表明,在实验研究范围内2.0GPa下获得的高压结晶样品的熔点和结晶度最高,分别达到208.5℃和64.6%。SEM结果表明,与常压结晶样品相比高压结晶样品内部显示出更加致密的质地结构。此外,在样品断面还观察到了规则块状晶体的生成。TGA结果显示高压结晶样品的热稳定性显著高于纯PA1010。密度测试结果显示,高压结晶样品的密度几乎均高于纯PA1010,而且高压熔体结晶样品的密度随着压力的升高而增大。     

烟叶样品在进行近红外分析测试前的样品处理方法

本发明涉及烟叶样品在进行近红外分析测试前的样品处理方法，属烟草样品的近红外光谱分析测试技术领域。本发明的烟叶样品在进行近红外分析测试前的样品处理方法包括干燥粉碎及压样三步骤，其中：a．粉碎步骤为：将干燥的样品取出并静止10S后放入家用食物搅拌器中进行粉碎处理，粉碎时间为20-30S，粉碎粒度达375μm以下；b．压样步骤为：将质量为300g的重锤自然平稳置入装有粉碎后样品的样品杯中，取出重锤，随后将样品杯放入仪器样品池内进行测量10min就能完成一个烟叶样品的测试工作。本发明具有操作简单、节省时间、成本低、效率高等优点。     

改进QuEChERS-气相色谱/质谱法测定食源性植物中烟碱及次要生物碱

采用改进QuEChERS方法,以0.01%三乙胺-甲基叔丁基醚溶液对样品中生物碱进行涡旋提取,用High pigment PSA对提取物进行净化,结合气相色谱/质谱法,建立了食源性植物(牛肝菌、茶叶和西红柿)中烟碱和5种次要生物碱的检测方法。优化了实验参数,最终牛肝菌、茶叶和西红柿3种样品加标回收率在84.1%~109.1%之间,日内及日间精密度分别小于9.4%和8.2%,目标物的检出限在0.0694~0.18mg/kg之间,线性相关系数R2≥0.993。采用本方法处理16个茶叶样品、6个牛肝菌样品、3个西红柿样品、1个土豆样品、1个茄子样品和1个辣椒样品并进行测定,结果发现烟碱在所有样品中均有不同程度的检出,降烟碱、新烟碱、麦斯明、假木贼碱和可替宁在部分样品中有检出。     

冷压塑形制样-光电直读光谱法测定碳素钢钢丝中C、Si、Mn、P、S、Cr、Ni、Cu的含量

用冷压法将外径在0.5mm以下的碳素钢钢丝样品加工制成直径为40mm的圆片状样品,供光电直读光谱测定C、Si、Mn、P、S、Cr、Ni、Cu。将碳素钢钢丝样品(外径小于0.5mm)置于高温炉中,在0.3MPa压力的氩气气氛中于825℃保温30min作退火处理,将样品冷却至常温(注如样品为低碳钢,无需退火处理)。用砂纸将样品打磨至金属光泽,用无水乙醇擦洗并晾干。将样品剪成长为40mm的小段,放入压样机的铝杯内,加盖。根据样品的抗拉强度选择合适的压力值和时间值,以缓慢加压模式将样品压制成直径为40mm的圆片状样品用于直读光谱分析。对所制分析样品以3点激发的方式测定了上述8种元素。经与国家标准方法湿法分析结果对照,两种方法的结果完全相符,证明方法所制备的样品具有良好的可靠性和适用性。     

王水溶解-电感耦合等离子体发射光谱法测定铁矿石中的微量磷

样品经王水分解后,在电感耦合等离子体发射光谱仪上测定了样品溶液中磷的含量。通过实验确定了基体元素的干扰、酸度、样品提升量、雾化气流速、功率、观测高度、分析谱线等分析条件。通过铁的干扰实验结果表明,样品中的基体元素铁不影响磷含量的测定。在用Ｐ178.222 nm分析线测定时,方法的检出限为P 0.0006％（相对于0.1ｇ样品,定容至100 mL）,相对标准偏差在3.14%～6.04％（ｎ＝11）,样品加标回收率在92%～110%。方法测定样品中磷含量的结果同光度法测定结果对比数据相符。     

流化床聚合反应器两种操作模式下乙烯共聚物的链结构与力学性能

采用制备型升温淋洗分级方法,对流化床聚合反应器在持液操作模式和冷凝态操作模式下生产的A、B两种乙烯/1-丁烯/1-己烯三元共聚物进行了分级,并结合多种分析手段对样品及其各级份进行了结构表征,同时测试对比了A、B两种聚乙烯样品的力学性能.结果表明,与冷凝态操作模式生产的聚乙烯样品B相比,持液操作模式下生产的聚乙烯样品A的拉伸屈服强度、拉伸断裂强度、断裂伸长率、冲击强度和雾度都比样品B优异.样品A的低温淋洗级份相对含量低于样品B,而其高温淋洗级份相对含量高于样品B;样品A低温淋洗级份的分子量略低于样品B,而其高温淋洗级份的分子量高于样品B;样品A的薄片晶含量和厚片晶含量都比样品B多,同时样品A的片晶厚度分布比样品B宽;样品A的总支化度以及每个级份的支化度都比样品B高,且样品A的支链在分子链间的分布比样品B宽,即样品A的支链比样品B的支链更倾向于生长在高分子量部分.通过以上表征分析,发现持液操作模式下生产的样品A比冷凝态操作模式下生产的样品B的物理使用性能更加优异,适合制备高性能的拉伸缠绕膜.     

扫描电镜与能谱仪

<正>扫描电镜利用精细聚焦电子束照射在样品表面,该电子束可以是静止或在样品表面作光栅扫描。在这个过程中,电子束与样品相互作用产生各种信号,其中包括二次电子、背散射电子、俄歇电子、特征X射线和不同能量的光子等,这些信号来自样品中的特定区域,分别利用探测器接收,可以提供样品的各种信息,用于研究材料的微观形貌、晶体学特征和微区化学成分。X射线能谱仪是扫描电镜附带的附件,通过检测从样品出射的特征X射线的波长或能量,测定样品元素的组成、相对含量以及分布。     

组织样品的直接质谱分析及其应用

质谱技术具有灵敏度高、分析速度快、能提供分子结构信息等特点,在生命科学研究领域扮演着重要角色,常用于组织样品分析。传统地,组织样品分析一般需经过研磨、萃取、分离等繁杂的预处理过程,导致耗时低效,无法满足大量样品高通量分析的实际需求,且不可避免地使组织样品中的一些活性成分损失。近年来,随着新型常压质谱技术的发展,使得组织样品可在无需样品预处理的条件下进行实时、非破坏、在线直接质谱分析,大大提高了分析效率。该文着重介绍了新型直接质谱技术在组织样品分析中的应用,并简要展望了该技术在生命科学、临床医学、食品科学、活体分析等领域的发展趋势。     

二维液相色谱在药物和毒物分析中的应用进展

生物样品中药物、毒物及内源性物质的定性与定量分析在生命科学和药物研发中发挥重要作用。生物样品的基质复杂,干扰物多,待测物浓度与内源性物质相比明显偏低,且样品取样量少,因此要求生物分析方法的特异性强、灵敏度高、重现性好。二维液相色谱技术具有峰容量大、显著降低复杂样品的基质效应和残留现象,及可以实现样品分析的自动化等特点,已成为生物样品分离分析的有力工具,在环境、食品和药物分析中得到广泛应用。本文在简要介绍了二维液相色谱原理装置基础上,对其在生物样品中药物、毒物和内源性物质分析中的应用进展进行了综述。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.