中空磁性金属微纳米材料的特性及应用研究进展

中空磁性金属微纳米材料因其具有超大比表面积,生物相容性及优异的电、光、化学和磁特性,在国防民生、催化、能源环境、生物医学等领域广泛应用。结合国内外研究现状,就中空磁性金属微纳米材料的吸波性能、催化特性、电化学特性、生物相容性和磁特性及其应用等方面的研究进展、尚存问题和未来发展趋势展开述评。     

不同液化条件下生物质残渣的燃烧特性研究

对锯屑在不同液化条件（溶剂、气氛、温度、催化剂）下所得液化残渣在热天平上进行了燃烧特性研究，通过比较液化残渣燃烧的三个特征温度，着火点ti、燃烧峰温tp和燃烬温度tb，分析了液化条件对残渣燃烧特性的影响。同时通过热重曲线所得数据探讨了液化残渣燃烧过程的动力学，并计算了活化能和频率因子 。结果表明，不同溶剂下所得液化残渣的燃烧特性显著不同，以四氢萘为溶剂所得液化残渣具有较好的燃烧特性；不同气氛下所得残渣的燃烧特性没有明显的不同；350℃下所得液化残渣的燃烧特性要好于300℃下所得液化残渣的燃烧特性；由于催化剂的影响，加入1%Mo后降低了所得液化残渣的燃烧特性；液化残渣的燃烧反应符合两段一级反应动力学。     

碳量子点激发依赖荧光特性的机理、调控及应用

碳量子点（carbon dots,CDs）是一种具有强荧光、荧光波长可调、无光漂白等特性的新型荧光纳米粒子,其制备简单、成本低,而且具有良好的生物相容性和低毒性,在光电器件、生物传感及药物载体等领域展现出广阔的应用前景。其具有的独特激发依赖荧光特性是指随着激发波长的改变,其发射波长将随之改变,所以,通过调节激发波长即可实现CDs的连续全色发射,可为其在多色成像生物领域提供可能性。此外,在长波长激发下,CDs发射波长甚至可以延续到近红外区域,展现出在活体成像领域的应用前景。因此,探索CDs激发依赖荧光特性的机理是非常重要的,这将为实现CDs的激发依赖荧光特性提供理论指导。本文就近年来人们对于CDs激发依赖荧光特性的研究进行了综述,重点概述了CDs激发依赖荧光特性的机理、调控实现CDs激发依赖荧光特性的方法及CDs激发依赖荧光特性的应用。目前,CDs激发依赖荧光特性的机理主要包括：不同表面态的分布、宽的尺寸分布、碳核结构的存在及周围慢的溶剂弛豫;实现CDs激发依赖荧光特性的方法主要有：对表面态的控制、尺寸分布的控制及碳核结构的控制;CDs激发依赖荧光特性的应用主要表现在细胞成像和光电器件。最后,对这一特性研究中尚存在的问题进行了总结并且展望了其发展前景。     

热力学关系的图形记忆法

设计了两种热力学关系记忆图,一种是矢量图,另一种是弧线图。将特性函数所对应的特征变量、特性函数之间的关系、特性函数的微分表示、Maxwell关系式和状态参量的偏微分表示纳入其中。用简单易记的形式使系统的热力学性质推演中常用的繁杂的公式记忆简化,有利于提高记忆的准确度和牢固度。     

煤、焦炭国家标准样品物理化学特性的稳定性考察及评价

从煤质材料、生产制备工艺方面介绍了影响煤、焦炭标准样品物理化学特性稳定性的因素,以实际煤、焦炭国家标准样品为例,考察了煤、焦炭标准样品物理化学特性值的稳定性,介绍了煤、焦炭标准样品稳定性评价的方法.根据稳定性考察结果,提出了保证煤、焦炭标准样品物理化学特性稳定性的措施.     

多层碳纳米球的研究

用弧光放电法制备了碳的巴基葱.用原子力显微镜（AFM）、扫描隧道显微镜（STM）和透射电镜（TEM）研究了在高定向石墨(HOPG)和金(Au)基底上的巴基葱的行为和电学特性.扫描隧道谱表明,巴基葱的电学特性具有与单壁碳纳米管相似的非线性特性.较小尺寸的巴基葱呈半导体特性,尺寸增大倾向金属线性.AFM/STM图像显示,在HOPG和Au基底上的巴基葱能够聚集成二聚体.利用较小尺寸巴基葱的电学非线性特性,有希望构造纳米电子学的单电子器件.     

树状高分子的特性粘数与代数的关系

从爱因斯坦的粘度理论出发 ,联系树状高分子的分子结构参数 ,计算了树状高分子的特性粘数 ,得到了树状高分子的特性粘数与代数的内在关系 ,分析了树状高分子特性粘数特异行为的内在原因 ,使得对树状高分子特性粘数的理论预测成为可能     

水煤浆分散剂与煤之间的相互作用 Ⅷ木质素磺酸钠对煤的成浆性与水煤浆流变特性的影响

水煤浆分散剂与煤之间的相互作用 Ⅷ木质素磺酸钠对煤的成浆性与水煤浆流变特性的影响;水煤浆; 流变特性; 成浆性; 木质素磺酸钠; 吸附特性     

测定零切变速度下特性粘数的简便方法

引言高分子溶液的特性粘数是一个十分重要的物理量。它和大分子的化学结构、分子量和大分子在溶液中的形态、尺寸大小等重要特性有关。特性粘数和分子量之间的联系更被广泛地利用于测定分子量。因此,如何准确而又简便地测定特性粘数值一向被人们所重视。无数实验事实表明,高分子溶液并非牛顿流体。特性粘数随切变速度的增加而下降,其下降量的大小随分子链刚硬程度、溶剂性能良好程度和分子量的增     

基于CO2气体释放法的煤燃烧特性研究

国内火电厂目前对于煤质的检测主要是通过常规的工业分析检测燃煤挥发分、碳、灰分和发热量等指标信息,指导锅炉的运行。在这些常规分析指标中,反映煤的燃烧特性主要是挥发分的多少。但是,仅凭挥发分来衡量煤的燃烧特性是不完全的[1]。此外由于条件限制,目前火电厂对于着火、燃尽等燃烧特性,无法得到。此前,国内一些研究单位采用热重分析技术对我国动力煤燃烧特性进行系统研究,并得到相应的指标。但由于热分析仪大都是从国外进口,仪器成本过高而无法推广和普及。本研究采用基于ＣＯ2气体释放法的煤燃烧特性研究可以较快得出煤的着火点、…     

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.     

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.     

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.     

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.     

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.     

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.     

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.