环氧端基酚酞聚芳醚腈的合成及结构性能表征

由酚酞和２，６二氯苯甲腈经亲核缩聚反应制得了含—ＯＫ端基的聚醚腈低聚物．在碱金属碳酸盐Ｋ２ＣＯ３／Ｈ２Ｏ催化下，将其与环氧氯丙烷反应得到了含环氧端基聚醚腈（ＥＰＣＥ）．用ＦＴＩＲ、１ＨＮＭＲ和ＤＳＣ等方法对ＥＰＣＥ树脂的结构性能进行了表征．测定了ＥＰＣＥ树脂的环氧值、溶解性、分子量及分子量分布．讨论了单体的摩尔比、反应温度。

结构性花岗岩残积土三轴试验研究

花岗岩残积工作为一种特殊土,在我国东南地区分布广泛,但其特殊的结构特性使得该类土体的工程事故频发。针对广东省肇庆市播植县某边坡残积土进行了一系列三轴试验,研究结构性花岗岩残积土在三轴应力状态时的应变和孔压变化特征,以及结构性花岗岩残积土的剪切结构性屈服特性,为相关工程提供借鉴。三轴压缩试验分别针对原状土、重塑正常固结土和重塑超固结土,试验结果表明,原状土和重塑超固结土均表现出一定的结构性,排水剪切时均表现出明显的剪胀性,应力-应变曲线均表现出应变软化,不排水剪切的超静孔压均为先增大后减小,但原状土超静孔压减小的幅度更大;超固结土的不排水抗剪强度符合SHANSEP理论,试验常数Λ_(0)为0.67;重塑正常固结土的归一化刚度随着加载的进行缓慢减小,ε_(1)=15%左右时完全屈服;原状土和重塑超固结土的归一化刚度曲线不能重合,分别于ε_(1)=1.5%和ε1=1%左右发生结构性屈服,并且均在ε_(1)=15%左右发生整体破坏,围压越大,结构性土的刚度曲线变化规律越接近于扰动土。

可操作物体识别过程中的两种操作动作表征

已有大量研究表明,视觉背侧通路中的背侧-背侧通路和腹侧-背侧通路分别表征与物体相关的抓握和使用动作,形成结构性和功能性操作动作表征。这两种操作动作表征在神经基础、激活条件、时间进程,以及与长时记忆的联系方面都存在差异,并且共同参与到可操作物体的识别过程中。关于结构性和功能性操作动作表征的研究不仅证明了操作动作信息对于可操作物体识别的重要性,而且对于深入研究物体如何在大脑中表征具有重要意义。

高分子基纳米复合材料制备、表征方法及应用

综述了高分子基纳米复合材料几种重要的制备方法,包括插层法、溶胶-凝胶法、共混法、原位聚合法、微乳液聚合法和LB膜法;介绍了常用的几种结构性能表征方法和在涂料、医用材料、电子功能材料等领域的应用。

碳纳米管用核壳聚合物前驱体的合成及性能

采用丙烯腈和甲基丙烯酸甲酯在75℃无皂乳液聚合合成核壳结构的聚甲基丙烯酸甲酯/聚丙烯腈核壳聚合物作为碳纳米管的前驱体。对合成核种子胶乳和聚甲基丙烯酸甲酯/聚丙烯腈核壳聚合物的反应条件进行了研究。用透射电镜、红外光谱、热重和差示热分析等对种子和核壳聚合物结构和性能进行了表征。结果表明,核壳聚合物具有较好的圆形度,核层直径大约350 nm,壳层厚度100 nm左右。核壳聚合物和种子聚合物具有不同的热性能特征。

硬脂酸改性聚乙烯醇/纳米纤维素复合阻隔涂料的制备

目的 为了以安全环保的方式提高聚乙烯醇(PVA)阻水阻气性,制备高阻隔PVA涂料,提高PVA的性能与应用范围。方法 在聚乙烯醇中填充纳米纤维素(Cellulose Nanofiber,CNF),并在此基础上添加硬脂酸进行耐水改性,探究对阻隔性能的影响,利用傅里叶红外光谱,X射线衍射,氧气、水蒸气透过率测试仪对其进行结构性能表征。结果 硬脂酸与PVA的酯化反应可以提高涂层的耐水性,PVA与CNF间能产生氢键,提高涂层结晶性能与阻隔性能,适量的硬脂酸的加入未降低CNF的结晶度,只降低了PVA的结晶性能,硬脂酸添加量为16%时涂层水蒸气透过率达到最低2.2 g/(m2·d),氧气透过率达到1.3cm3/(m2·d)。结论 利用CNF填充与硬脂酸酯化协同改性制备的PVA阻隔涂料具有较高的阻隔性能,使其在阻隔涂层方面具有广阔的应用前景。

Preparation, characterization and catalytic performance of single-atom catalysts

Supported and colloidal single‐atom catalysts(SACs),which possess excellent catalytic properties,are particularly important in both fundamental studies and practical applications.The progress made in the preparation methods,characterization,catalytic performances and mechanisms of SACs anchored to metal oxides,two‐dimensional materials and the surface of metal nanoclusters(NCs)are reviewed.The different techniques for SAC fabrication,including conventional solution methods based on co‐precipitation,incipient wetness co‐impregnation,and the chemical vapor deposition method,as well as the newer atom layer deposition(ALD)and galvanic replacement methods,are summarized.The main results from experimental and theoretical studies of various catalytic reactions over SACs,including oxidation reactions,hydrogenation,water gas shift,photocatalytic H2evolution and electrochemical reactions,are also discussed.Moreover,the electronic properties of the single atoms and their interactions with the supports are described to assist in understanding the origin of the high catalytic activity and selectivity of SACs.Finally,possible future research directions of SACs and their applications are proposed.

Design and Synthesis of Novel Fluorine-containing Acrylates

A series of novel fluorine-containing acrylates 6a-6g were synthesized via the condensation of ethyl cyanoacetate and trifluoroacetic anhydride, followed by chloridization and the coupling reaction with amines. These new compounds exhibited some biological activity as preliminary bioassay indicated. A plausible reaction mechanism was outlined and discussed.

Structure Characterization of Fluorosilicone Oils

Fluorosilicone oil is polysiloxane with alkyl side chains containing fluorine, and because of its excellent thermal oxidation stability, cold flow property and cryogenic property, it can be widely used as a high temperature lubricant in the field of military aerospace industry. Two kinds of fluorosilicone oils, FSiO-a and FSiO-b, were synthesized by different pro- cessing means. FTICR MS was used to collect the information on composition and structure of the two polymers, respec- tively. The test results show that the two fluorosilicone oils have different contents of fluorine-containing chain segments (m/ n value), the maximum distribution of m/n value of FSiO-a oil ranges from 0.22 to 0.25, and that of FSiO-b oil ranges from 0.4 to 0.67. Difference in synthesis techniques makes this discrepancy and affects the quality and thermal stability of the fluoro- silicone oils.

Synthesis of Iron-Pyridoxine Complex by Solvothermal Process, Its Structural Characterization and Antioxidant Activity Evaluation

Hydroxyl radicals, superoxide anions and nitricoxide radicals are reactive species that can attack biomolecules such as DNA, lipids and proteins to cause many lifestyle-related diseases including hypertension and photoaging. This study reports the synthesis of new copper-pyridoxine and iron-pyridoxine complexes. The complexes have been synthesized and characterized by molar conductances, IR, UV-Visible, mass spectrometry, melting points and magnetic moment datas. The molecular formula of the complex is found to be Fe（py ^-）2Cl.H2O. The pyH/pyligand is coordinated to copper and iron through N atom of the pyridine ring and O atom of 5＇-CH2OH group. The Fe（III） complex is found to be paramagnetic with one unpaired electron. The antioxidant activities of the free ligand and its complexes were determined in vitro.

Restructuring of well-defined Pt-based electrode surfaces under mild electrochemical conditions

Since the 1980s,single-crystal Pt electrodes with well-defined surface structures have been deemed stable under mild electrochemical conditions(e.g.,in the potential region of electric double layers,underpotential deposition of hydrogen,or mild hydrogen evolution/OH adsorption)and have served as model electrodes for unraveling the structure-performance relation in electrocatalysis.With the advancement of in situ electrochemical microscopy/spectroscopy techniques,subtle surface restructuring under mild electrochemical conditions has been achieved in the last decade.Surface restructuring can considerably modify electrocatalytic properties by generating/destroying highly active sites,thereby interfering with the deduction of the structure-performance relation.In this review,we summarize recent progress in the restructuring of well-defined Pt(-based)electrode surfaces under mild electrochemical conditions.The importance of the meticulous structural characterization of Pt electrodes before,during,and after electrochemical measurements is demonstrated using CO adsorption/oxidation,hydrogen adsorption/evolution,and oxygen reduction as examples.The implications of present findings for correctly identifying the reaction mechanisms and kinetics of other electrocatalytic systems are also briefly discussed.

Nanomagnetic CoPt truncated octahedrons:facile synthesis,superior electrocatalytic activity and stability for methanol oxidation

Nanomagnetic CoPt truncated octahedral nanoparticles （TONPs） were successfully synthesised through a facile one-pot strategy. These single crystal CoPt TONPs with an average size of about 8 nm exhibit excellent electrocatalytic performance of both activity and stability for methanol oxidation reaction （MOR）. The mass and specific activities of CoPt TONPs is 8 and 6 times higher than that of standard commercial Pt/C, respectively. After accelerated durability test （ADT）, the loss of electrochemical surface area （ECSA） for CoPt TONPs is only 18.5%, which is significantly less than that of commercial Pt/C （68.2%）, indicating that CoPt TONPs possess much better stability than commercial Pt/C in the prolonged operation. The Curie temperature of CoPt TONPs down to 8 nm is as high as 350 K with weak ferromagntism at room temperature （RT）, which is greatly valuable for recycling in the eletrocatalytic applications.

Structure characterization,magnetic and photoluminescence properties of Mn doped ZnS nanocrystalline

Wurzite ZnS:Mn nanorods are synthesized via a solvothermal method by using ethylenediamine and water as mixed solvent.The diameters of the nanorods increase and the lengths decrease with the Mn concentration.High resolution transmission electron microscopic images illustrate that a few cubic ZnS:Mn nanoparticles arise along with hexagonal nanorods on high Mn concentration.The samples set off yellow-orange emission at 590 nm,characteristic of 4 T→ 6 A 1 transition of Mn 2+ at T d symmetry in ZnS.Electron spin resonance spectrum of the nanorods shows that high Mn concentrations produce a broad envelope,whereas six-line hyperfine appears for lower Mn concentrations.These results together with the magnetization curves indicate that all the ZnS:Mn samples are paramagnetic even down to 4 K,which suggests that the ZnS:Mn is not suitable for dilute magnetic semiconductor.

Chiral Oxazaborolidine-catalyzed Asymmetric Borane Reduction of Alkyl 4-Dialkylaminophenyl Ketones

A series of alkyl 4-dialkylaminophenyl ketones were prepared and reduced asymmetrically by borane under the chiral oxazaborolidine catalysis. The results indicate that the ketones show a more obvious subsfituent effect on the enanfioselectivity than the corresponding 4-alkyl/alkoxy/alkylthiophenyl ketones in the asymmetric reduction because of the existence of a strong coordinate nitrogen atom with the boron atom in the catalyst and borane.

Thorium/uranium mixed oxide nanocrystals： Synthesis, structural characterization and magnetic properties

One of the primary aims of the actinide community within nanoscience is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects （e.g., nanocrystals） are necessary. Hence, a ＂library＂ dedicated to the preparation of various actinidebased nanoscale building blocks is currently being developed. Nanoscale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nanocrystals （both for thorium and uranium, and recently extended to neptunium and plutonium）. In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nanocrystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate （together with additional capping agents） into benzyl ether can be used to synthesize thorium/uranium mixed oxide nanocrystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium：uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nanocrystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nanocrystals of non-magnetic oxides as recently claimed in the literature.

Adsorption Models and Structural Characterization for Activated Carbon Fibers

The nitrogen adsorption isotherms at 77.69 K were measured for two samples of activated carbon fibers and their microstructures were investigated. Among established isotherm equations, the Dubinin-Radushkevieh equation showed the best agreement with the experimental data, while the Langmuir equation showed a large deviation when employed at low relative pressures. The MP method, t-method and as-method were used to analyze the pore size distribution. The calculated average pore widths and BET （Brunauer-Emmett-Teller） surface areas for the sample A-13 were 0.86 nm and 1 286.60 m^2/g, while for the sample A-16, they were 0.82 nm and 1 490.64 m^2/g. The sample with larger pore width was more suitable to be used as additive in chemical heat pumps, while the other one could be used as adsorbent in adsorption refrigeration systems .

One-dimensional lanthanide complexes bridged by nitronyl nitroxide radical ligands with non-chelating nitrogen donors: Structure and magnetic characterization

A series of new lanthanide-radical complexes [{Ln（hfac）3}2（NITPhlM）2] （Ln = Nd （1）, Eu （2）, Tb （3）, Er （4）; hfac = hexafluoroacetylacetonate; NITPhlM = 2-[4-（1-imidazole）phenyl]-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide） have been prepared and characterized. Single crystal X-ray diffraction analyses reveal that these complexes are isostructural with one-dimensional chain structures. These consist in Ln（hfac）3 units bridged by the paramagnetic ligands by the means of coor- dination of their nitronyl nitroxide groups and imidazole rings. Interestingly, each Ln ion is either bound to two nitronyl ni- troxide groups or to two imidazole units, and the different Ln centers alternate along the chain. Magnetic studies show that complex 3 exhibits a single-chain magnet behavior.