“右旋糖酐-磁性层状复合氢氧化物-氟尿嘧啶”给药系统的超分子组装表征与急毒性水平

用"前体共沉淀-离子交换插层-原位复合-溶剂转换"技术合成"右旋糖酐-磁性层状复合氢氧化物-氟尿嘧啶"(DET-MLDH-FU,DMF)运载系统,通过XRD,IR,TEM,TG表征及体外释放实验研究了DMF的物相特征与缓释性能,通过对小鼠灌胃和腹腔注射给药考察了DMF与载体MLDH的急毒性水平.结果表明,DMF等超分子的XRD与R-六方LDH衍射特征相符,是Fe3.6Fe0.9(O,OH,Cl)9型LDH及微量Fe3O4的复合晶相,DMF具有DET,MLDH与FU分级组装形成的核壳式构造.体外pH 7.35 PBS溶出介质中,DMF的药物释放遵守零级模型C-1.162×10-5=4.566×10-7t,速率常数4.566×10-7 mol-1?L?m-1.DMF,MLDH-FU及MLDH可经正常代谢排出体外,口服毒性小;腹腔注射DMF的LD50为2542.8 mg?kg-1,MLDH的LD50为1951.0 mg?kg-1,均属低毒性物质.DET的复合组装对Fe(II,III)LDH构架有抗氧化保护作用,对不同MLDH-FU粒子进行选择、分离与包封,提高MLDH-FU的缓释效果、强化MLDH的控释性能,降低给药系统DMF的急毒性水平.     

空气条件下高温固相合成层状LiMnO2及其离子交换的影响规律

在空气中高温固相反应合成了层次单斜结构前驱体NaMnO2，在不同条件下进行离子交换反应，得到LiMnO2。用X射线衍射法表征了前驱体及交换产物的晶体结构，用电感耦合等离子体光谱进行元素含量分析，用扫描电镜测定晶体的形貌。结果表明，离子交换反应条件对反应速率和产物的晶体结构与组成有重要影响。     

水合NaX沸石与碱金属盐类间的固相离子交换

通过XRD和吡啶吸附的IR技术考察了水合13X沸石与碱金属盐类间的固相离子交换反应,结果表明,此类固相离子交换在室温下即可发生。一次交换的程度有限,通过重复交换可提高交换度,体积较大的Cs⁺比K⁺难于交换,高温焙烧有利于提高Cs⁺的交换度。     

超级铝热剂Al/CuO前驱体的制备、表征、热分解机理及非等温分解反应动力学

以硝酸铜、无水乙醇、1,2-环氧丙烷和纳米铝粉为原料, 在超声振荡条件下, 采用溶胶-凝胶法制备了纳米复合含能材料——超级铝热剂Al/CuO的前驱体. 利用热重-差示扫描量热-傅里叶变换红外-质谱(TG- DSC-FTIR-MS)联用技术, 研究了纳米Al/CuO溶胶-凝胶前驱体的热行为和分解过程及机理. 利用不同升温速率下的TG-DTG分析, 研究了纳米超级铝热剂Al/CuO的溶胶-凝胶前驱体的热分解反应机理, 采用了6种动力学分析方法进行动力学参数计算, 得到前驱体分解反应的表观活化能、反应级数、频率因子等动力学参数, 纳米Al/CuO前驱体分解反应的动力学方程为: dα/dt=10^14.0×4α^3/4exp(-2.0×10⁴/T).     

含铈类水滑石的制备及其衍生物催化研究

采用共沉淀水热法制备了镍铝铈三元复合层状氢氧化物.详细探讨了合成体系pH值、Ce/Al比及陈化条件对合成产物物相的影响;通过XRD,ICP,TG-DTA手段研究了合成物物相、组成及热行为.考察了以合成物为前驱体经焙烧后转化为镍铝铈复合金属氧化物在催化消除NO反应中的应用.实验结果表明,合成镍铝铈三元复合层状氢氧化物的适宜条件是:M2 /M3 =2,Ce/Al=0.07～0.75,pH=5.5～6.9,水热处理条件为110℃,5 h;在pH=5.5～6.9条件下,合成原料配比不同,产物物相相同,但组成不同;合成物热稳定性较差,在T=100～400℃之间,层间吸附水及层间平衡阴离子NO3-脱去,转化为复合氧化物,将此氧化物应用于NO消除反应中,表现出高的低温活性,400℃进行反应,NO转化率达95%,N2选择性几乎100%.     

插层结构水滑石前驱体制备Cu/ZnO/Al_2O_3催化剂及其甲醇合成催化性能

分别采用共沉淀法、离子交换法和焙烧复原法制备Cu(C_2O_4)_2~(2-)络合阴离子插层ZnAl-LDH水滑石纯物相前驱体,经焙烧得到片层结构的Cu-ZnAl-LDO催化剂。通过XRD、TEM、ICP、H_2-TPR、N_2O-H_2氧化还原滴定及N_2物理吸附-脱附等方式对前驱体和催化剂进行表征分析,考察了不同制备方法对插层结构催化剂结构性质及其合成甲醇催化活性及稳定性的影响。结果表明,相比于离子交换法和焙烧复原法,共沉淀法制备的CP-Cu-ZnAl-LDH前驱体具有较完整的水滑石二维层状结构,且插层Cu组分含量最大,焙烧后层间高分散的Cu物种颗粒尺寸较小,与ZnO发生相互作用,表现出很好的催化活性,单位质量Cu的甲醇收率可达3412 mg/(g Cu·h);同时,层板对Cu物种的限域作用有效抑制了Cu颗粒的团聚长大,连续反应60 h过程中催化剂未发现失活。     

复合金属氧化物催化剂在光驱动合成过氧化氢中的原位转化及其性能研究

利用钛基复合金属氢氧化物作为前驱体,通过焙烧转化为钛基复合金属氧化物,作为光合成过氧化氢的催化剂.发现复合金属氧化物中的氧化锌晶相在合成过氧化氢反应中被原位溶蚀,逐步转变为TiO_2-ZnTiO_3相.复合金属氧化物与原位转化得到的TiO_2-ZnTiO_3都显示出比商品化的TiO_2(P25:80%锐钛矿和20%金红石混合相)更好的光合成过氧化氢性能.动力学分析表明,过氧化氢的生成由其生成速率与分解速率共同决定,TiO_2-ZnTiO_3作为催化剂时,过氧化氢的生成速率常数(K_f)是3.581μM/min,是复合金属氧化物作催化剂时(K_f=0.982μM/min)的3.65倍,是P25(K_f=0.852μM/min)的4.20倍.而相应的分解速率常数(K_d),TiO_2-ZnTiO_3(K_d=0.0472min~(-1))是复合金属氧化物(K_d=0.0119min~(-1))的3.97倍,是P25(K_d=0.0374min~(-1))的1.26倍.TiO_2-ZnTiO_3具有更大的生成速率常数和分解速率常数.因此,尽管TiO_2-ZnTiO_3在反应初期催化生成了更多的过氧化氢,但随着反应进行,TiO_2-ZnTiO_3催化合成的过氧化氢与复合金属氧化物达到几乎相同量,这表明催化剂的原位结构(物相)转变对反应动力学产生了影响,但并不显著改变过氧化氢的最终产量.抑制过氧化氢在催化剂表面的分解是提高其产量的重要途径.该工作加深了对钛基复合金属氧化物光催化合成过氧化氢的反应动力学认识,为钛基催化剂结构设计提供了一定指导.     

固-液相转移催化合成——Ⅲ.α-甲基苯丙氨酸的合成及苄基化反应的研究

本文以丙氨酸甲酯和苯甲醛生成的西佛碱衍生物(1)为底物,进行固-液相转移催化苄基化反应,得到的苄基化产物(2)经酸水解合成了α-甲基苯丙氨酸,考察了相转移催化条件下苄基化反应的影响因素及动力学行为,该反应具有表面反应的特性及自催化反应的动力学特征,提出了固-液相转移催化反应的可能机理。     

纳米CoSe修饰氮掺杂多孔碳的可控制备及其锂硫电池多硫化物的催化转化效应

锂硫电池中较差的循环稳定性和倍率性能是实现锂硫电池商业化的技术障碍,其主要原因之一是多硫化物在硫电极内的电化学转化速率较为缓慢。为此,我们以ZIF-9为前驱体,采用先碳化,再酸化刻蚀,最后硒化的方法合成了含少量催化剂的CoSe修饰氮掺杂多孔碳(CoSe/NC)电极材料,以期提高硫电极内多硫化物的电化学转化动力学性能,并通过流动液相三电极体系对该材料进行电化学动力学表征。结果显示,相较于对比材料,CoSe/NC能够加快多硫化物的氧化还原反应速率,在0.2mA·cm-2电流密度下,多硫化物氧化还原反应在CoSe/NC电极上有最小的反应过电位;同时,在0.1 V过电位下,各氧化还原反应也有最大的响应电流。因此,将CoSe/NC作为硫宿主材料组装电池展现了优异的电化学性能：在1C(1C=1 675 mA·g^-1)下初始放电比容量为1 068 mAh·g^-1,经过500次循环后,可逆容量仍保持在693 mAh·g^-1。另外,在3C的高电流密度下,放电比容量可高达819 mAh·g-1。     

海刺猬状微纳结构钴镍化合物的合成与表征(英文)

采用均相沉淀法,以Co(NO_3)_2·6H_2O和Ni(NO_3)_2·6H_2O为原料,尿素作为沉淀剂,成功制备出了新型海刺猬状微/纳复合结构。通过调节反应温度,反应物浓度和物质的量的比,所获得的前驱体呈放射状纳米线构成的海刺猬结构。随后分别在氧气氛和氢气氛下对制备出的前驱体进行热处理,利用FE-SEM、TEM、XRD以及VSM等测试手段对制备出的微/纳复合结构前驱体及热处理产物进行了形貌表征、物相分析以及磁学性能表征。在氧气氛条件下处理得到的产物具有良好的亚铁磁性,并且很好地保持了前驱体的结构与形貌。结合热处理产物的分析,对该海刺猬微纳结构前驱体提出了一种可能的形成过程和机理。另外,在氢气还原条件下处理得到的产物为多孔微纳米球状结构,呈现出更为优异的亚铁磁性。     

Synthesis pretreatment and characterization of a magnetic layered double hydroxides fluorescent probe

Using magnetic layered double hydroxide （MLDH） as carrier of fluorescein （FLU）, a fluorescent composite of MLDH-FLU was prepared via intercalation reaction of ion change. The crystal properties of MLDH-FLU were investigated through XRD, IR, TEM and TG-DSC characterization. It is shown that the crystal type of MLDH-FLU composite matched well with R-hexagonal crystal system of MLDH, with crystal cell parameters of a, c and channel height h equal to 0.3199, 2.411 and 0.3267 nm respectively. The superabundant pigment adsorbed outside the composite should be cleared before interference with cells, but excessive wash would decrease stability and cause crystal phase transformation of MLDH.     

Tungstocobaltate-pillared layered double hydroxides: Preparation, characterization, magnetic and catalytic properties

A new polyoxometalate anion-pillared layered double hydroxide (LDH) was prepared by aqueous ion exchange of a Mg-Al LDH precursor in nitrate form with the tungstocobaltate anions [CoW₁₂O₄₀]⁵⁻. The physicochemical properties of the product were characterized by the methods of powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. It was confirmed that [CoW₁₂O₄₀]⁵⁻ was intercalated between the brucite-type layers of the LDHs without a change in the structure. Magnetic measurement shows the occurrence of antiferromagnetic interactions between the magnetic centers. The investigation of catalytic performance for this sample exhibits high activity for the oxidation of benzaldehyde by hydrogen peroxide.     

Recent progress on preparation and applications of layered double hydroxides

The properties of layered double hydroxides (LDHs), including the adjustability of cations in host layers, exchangeability of anions between layers, and tunability of the crystal structure, render them unique characteristics in preparation and applications. Relating to the structural characteristics of LDHs, this work analyzes the research status, advantages and disadvantages of the synthetic methods for LDHs, including hydrothermal, electrodeposition, co-precipitation and anion exchange methods. In addition, the application status and prospects are reviewed, such as photo/electrocatalysis, electrochemical energy storage, magnetic materials, pollutant adsorption, and other fields. Lastly, the critical issues and solutions in the developing process of LDHs are analyzed and proposed.     

Hydrothermal synthesis and characterization of nanorods of various titanates and titanium dioxide

The formation process of titania based nanorods during hydrothermal synthesis starting from an amorphous TiO2.nH2O gel has been investigated. Sodium tri-titanate (Na2Ti3O7) particles with a rodlike morphology were prepared by a simple hydrothermal process in the presence of a concentrated NaOH aqueous solution. The ion exchange reaction of the synthesized Na2Ti3O7 nanorods with HCl under ultrasonic treatment promotes a complete sodium substitution and the formation of H2Ti3O7 nanorods. Low-temperature annealing of the as-produced nanorods of Na2Ti3O7 and H2Ti3O7 leads to a loss of the layered crystal structure and the formation of nanorods of condensed framework phases-sodium hexa-titanate (Na2Ti6O13) and metastable TiO2-B phases, respectively. These transformations proceed without a significant change in particle morphology. The nanostructures were investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and Raman spectroscopy. The structural defects of the synthesized nanorods were investigated by high-resolution electron microscopy. The presence of planar defects can be attributed to the exfoliation of the zigzag ribbon layers into two-dimensional titanates as well as to the condensation of the layers of TiO6 octahedra into three-dimensional frameworks.     

Planar and non-planar solidification of optically organised smectic films

This letter describes an original freezing process that yields homogeneous solid films at ambient temperature with preservation of the layered structure of the chiral smectic phase. One of the most remarkable features of the process is its ability to provide complexly bent films with arbitrary three-dimensional shapes. Their optical homogeneity is observed in the planar as well as in the bent films. The method is very simple. After forming the films by spreading the liquid crystal above a hole in a glass slice placed over a hot stage, the film is heated from below. The hot film is exposed to ambient temperature. Then, a solid object at room temperature with a specifically adapted shape is immersed in the liquid film. The mechanical constraints imposed by the object curves the film and stabilises various solid two- and three-dimensional structures. Their homogeneous optical properties are due to long-range organisation of the molecular orientation (tilt), which combines with a complex helical arrangement of the frozen smectic layers.     

层状LiMnO_2正极材料的研究进展

层状LiMnO2 化合物的研究是目前锂离子电池正极材料锂锰氧化物研究工作的新热点 ,本文综述了近年来国内外LiMnO2 化合物的研究进展 ,主要阐述了具有层状和扭曲层状结构的m LiMnO2和o LiMnO2 的结构、电性能、合成和改性方法等方面的研究状况 ,重点介绍了离子交换法合成层状LiMnO2 的原因和机理。探索新的合成方法和掺杂其它金属离子改性以提高循环性能是今后LiMnO2 的研究趋势。     

聚酰亚胺类液晶光定向层材料的研究

经含有羟基的二胺单体HAB与二酐单体 4 ,4′ (六氟异丙基 ) 双邻苯二甲酸酐 ( 6FDA)的缩聚反应 ,制备了含有羟基的先驱聚合物PI OH ,通过PI OH上羟基与肉桂酰氯的酯化反应 ,制备了侧链带有肉桂酸酯基团的光敏聚酰亚胺PI CI.用氢核磁共振 ( 1H NMR)分析、傅立叶红外光谱 (FTIR)分析等表征了上述聚合物的结构与感光性能 .用紫外 可见光谱 (UV Vis)等方法研究了PI CI的光交联反应 .聚合物PI CI旋镀膜经线性偏振光聚合技术 (LPP)处理并装配得到的液晶盒可使液晶分子很好地定向沿面排列 .上述实验表明 ,本文所合成的聚酰亚胺定向层材料是一种新的液晶光定向层材料     

Synthesis and Characterization of Poly(ethylene terephthalate)/Modified Lithium‐Aluminum‐Layered Double Hydroxide Nanocomposites Prepared Using In‐situ Polymerization

Layered double hydroxides are a type of layered stacked compound, which can be intercalated with organic‐molecule modifiers. An ion‐exchange process for layered double hydroxide (LDH) was used to intercalate water‐soluble sulfanilic acid salt (SAS) and dimethyl 5‐sulfoisopthalate (DMSI) into lithium aluminum layered double hydroxides (LiAl LDHs). In this work, a hydrothermal process was used to modify LiAl LDHs, and the modified LiAl LDHs were treated with either SAS or DMSI through an ion‐exchange process and were then intercalated using bis‐hydroxyethylene terephthalate (BHET). The results indicate that the modified LiAl LDHs improved the interlayer compatibility between the PET and LiAl LDH layers; thus, enabling the oligomer molecules to more easily enter the gallery of the LiAl LDH layers so that polymer chains could be included between the LDH layers during polymerization of the matrix. The better barrier, mechanical properties, and thermal stability of these new types of PET nanocomposites are discussed.     

Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions

A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions.