分级多孔γ-Al2O3空心微球微波水热法制备及其对刚果红的快速吸附

以KAl(SO₄)₂和尿素为前驱体,通过微波水热法于180 ℃反应20 min,经600 ℃焙烧2 h制得分级多孔γ-Al₂O₃空心微球.所制备的样品被用于吸附典型有机染料刚果红(CR)溶液.结果表明,制备的γ-Al₂O₃空心微球直径为0.8-1.0 μm,厚度约为200 nm.此γ-Al₂O₃空心微球具有高的比表面积(243 m²·g^-1)和分级大孔-中孔结构,此结构非常有利于液相过程中的质量传递.微波水热法制备的γ-Al₂O₃空心微球比水热法制备的γ-Al₂O₃和商用的γ-Al₂O₃样品显示出更快和更强的吸附性能.此样品的吸附数据很好地符合假二级速率方程和Langmuir吸附理论模型.从Langmuir吸附理论模型计算得到微波水热法制备的γ-Al₂O₃空心微球的最大吸附量(q_max) 25 ℃时高达515.4 mg·g^-1.由于具有分等级结构、高比表面积、大的孔容和吸附能力,微波水热法制备的γ-Al₂O₃空心微球样品有望成为一种具有很好应用潜力的环境吸附剂.     

五氧化二钒空心球制备及其作为镁二次电池正极材料

利用碳球作为模板,通过与异丙醇氧钒的溶剂热反应制备了五氧化二钒(V₂O₅)空心球。 采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)等技术手段对V₂O₅空心球进行了表征。 实验结果表明,V₂O₅空心球的直径约为1.5 μm,壁厚约100 nm。 将V₂O₅空心球作为镁二次电池的正极,在0.2 C充放电条件下,材料的首次放电比容量达140 mA·h/g,经20次循环后容量为110 mA·h/g。     

Research on Ice Crystal Growth Inside the Vitrified Vs55 with Magnetic Nanoparticles During Devitrification by Cryomicroscopy

The effect of magnetic nanoparticles(mNPs) on the devitrification crystallization of typical vitrification solution Vs55 was systematically explored by differential scanning calorimetry(DSC) and cryomicroscope system. The results show tliat,(i) the mNPs coated by both carboxylic acid(CA) and polyethylene glycol(PEG) had little effect on the glass transition temperature(rg) of Vs55, but had significant effect on the devitrification transition temperature(7a) and devitrification enthalpy(Hrd),(ii) in the range of the devitrification area(-85- 0℃), the MNPs coated by CA can significantly accelerate the devitrification of Vs55 as the isothermal temperatures and the cooling rates increased, and the ice growth rate was 0.37 p.m/s at the isothermal temperature of-85 ℃, and was about 2.19 gm/s at -75℃. Also, the ice growth rates rose from 1.72 pm/s to 3.54 pm/s when the cooling rates were increased from 2 ℃/min to 100 ℃/min(at the isothennal temperature of -75℃),(iii) magnetic nanoparticles coated by both PEG and CA could promote the devitrification of Vs55, for instance, without any crystal growth inside Vs55 at the isothermal temperature of-80℃, but 1.04 and 2.31 gm/s for adding magnetic nanoparticles coated by CA and PEG, respectively. Compared with the samples coated by CA, PEG promoted the devitrification of Vs55 in a much more positive way, and the ice growth rates were 0.62 and 6.25 μm/s at the isothermal temperatures of -85 and -75 ℃, respectively. Tliese results indicate that the surface coating of MNPs could significantly affect tlie recrystallization of Vs55, and further work should be conducted in the future research.     

含C60聚苯乙烯微球的制备及光电导性能研究

目前,多功能、高性能聚合物微球的合成及应用已成为研究热点.制备聚合物微球的方法有乳液聚合法、分散聚合法、无皂乳液聚合法、超微乳液聚合法和悬浮聚合法等.制备微米级微球通常采用乳液聚合法和分散聚合法.     

Preparation and optical properties of three-dimensional navel-like Bi2WO6 hierarchical microspheres

Three-dimensional (3D) navel-like Bi₂WO₆ hierarchical microspheres were successfully prepared using a simple hydrothermal method. The 3D navel-like BWO hierarchical structure composed of well-ordered nanosheets displayed the excellent photocatalytic activity, and the degradation rate of norfloxacin was about 67%.     

Synthesis of NiFe2O4 Nanowires with NiO Nanosheet as Precursor via a Topochemical Solid State Method

Large scale NiFe₂O₄ nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe₂O₄ annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Fe^- ions into NiFe₂O₄ nanowires. In the beginning stage of synthesizing process, the shape of NiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400℃ to 600℃. At last they transformed into nanoparticles from 700℃ to 1000℃. Thus, the optimized annealing temperature was selected as 600℃ because the NiFe₂O₄ obtained at 600℃(N600) exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m²/kg and the lowest coercivity(H_c) of 8914 A/m.     

Preparation and Properties of Thermoplastic Expandable Microspheres with P(AN-MMA) Shell

Thermoplastic expandable microspheres (TEMs) having a core/shell structure were prepared via suspension polymerization with acrylonitrile (AN) and methyl methacrylate (MMA) as monomers and i-butane as blowing agent. The relationship between monomer compositions and expansion properties of the TEMs was explored. When the weight ratio of AN and MMA is 1: 1, suspension polymerization could yield TEMs having good expansion properties and heat stability at 120–130°C. The maximum expansion volume is 22.5 times of the original volume. The temperatures at the maximum expansion volume (T_m.e.), at the onsets of expansion (T_o.e.) and the onset of shrinkage (T_o.s.) are 80, 120–130, and 145°C, respectively. The micromorphologies were observed by polarizing optical microscope (POM), the results show that the TEMs have a core/shell structure. The blowing agent content in TEMs is–20 wt %, which was determined by thermogravimetric analysis (TGA). Dynamic light-scattering (DLS) measurements show that the TEMs have an average particle size of–20 μm and a wide particle size distribution. The presence of low-molecular alcohol in water phase could help to reduce the particle size distribution.     

Microwave-assisted One-pot Synthesis of Ag NPs/C and Its Application in H2O2 and Glucose Detection

The facile preparation of Ag NPs/C via a one-pot strategy was carried out by microwave treatment of a mixed aqueous solution of AgNO₃ and glucose at 180℃ for 20 min without the presence of extra reducing agent. The as-synthesized Ag NPs/C showed high catalytic performance toward the reduction of H₂O₂. The H₂O₂ sensor constructed with as-synthesized Ag NPs/C exhibited a short amperometric response time of less than 2 s. The linear range was approximately (0.1-50) mmol/L(r=0.997), and the detection limit was approximately 3.3 μmol/L at a signal-to-noise ratio of 3. A glucose biosensor was fabricated by immobilizing glucose oxidase onto Ag NPs/C- modified glassy carbon electrode to detect glucose. The glucose sensor had a wide linear response range of 2-22 mmol/L(r=0.999) and a detection limit of 190 μmol/L.     

Si衬底上生长的铁硅化合物结构和取向分析

采用分子束外延法分别在650-920℃的Si(110)和920℃的Si(111)衬底表面生长出铁的硅化物纳米结构,并主要分析了920℃高温下纳米结构的形貌、组成相及其与Si衬底的取向关系.扫描隧道显微镜(STM)研究表明,920℃高温下,Si(110)衬底上生长的铁硅化合物完全以纳米线的形式存在,且其尺寸远大于650℃低温下外延生长的纳米线尺寸;Si(111)衬底上生长出三维岛和薄膜两种形貌的铁硅化合物,其中三维岛具有金属特性且直径约300 nm、高约155 nm,薄膜厚度约2 nm.电子背散射衍射研究表明920℃高温下Si(110)衬底上生长的纳米线仅以β-FeSi2的形式存在,且β-FeSi2相与衬底之间存在唯一的取向关系:β-FeSi2(101)//Si(11 1);β-FeSi2[010]//Si[110];Si(111)衬底上生长的三维岛由六方晶系的Fe2Si相组成,Fe2Si属于164空间群,晶胞常数为a=0.405 nm,c=0.509 nm;与衬底之间的取向关系为Fe2Si(001)∥Si(111)和Fe2Si[1 20]//Si[112].     

Novel PLGA Microspheres for Sustained Delivery of Antisense Oligonucleotide

Novel poly(lactide-co-glycolide acid)(PLGA) microspheres were developed for sustained delivery of antisense oligonucleotide(ASO). First, a new cationic agent, polyethylenimine(PEI) conjugated to linoleic acid(LA)(PEI-LA) was synthesized by reacting PEI(M_w=800) with linoleoyl chloride. Then, PEI-LA was combined with LOR-2501 to form electrostatic complexes at moderate nitrogen-to-phosphate(N/P) molar ratios which were then encapsulated into poly(lactide-co-glycolide) microspheres by a multiple emulsion-solvent evaporation technique. With an increase in ASO/PEI-LA concentration from 5% to 10%, encapsulation efficiency of ASO in the microspheres reduced from 72.14% to 57.62%, and the particle size of microspheres increased from 28.58 μm to 34.76 μm. In vitro studies show that the release profile of ASO from microspheres prepared at 7.5% ASO-PEI-LA lasted for 14 d. The novel microspheres have a potential use as a sustained release vehicle for ASO.     

ZSM-5沸石大单晶的生长

ZSM-5是近十年来发展的具有广泛应用前景的高硅沸石分子筛。其骨架主要由五元环连结而成,具有十元环孔道(直径约6(?))。空间群为P_nma。大于40μm的均匀完美沸石单晶体,为晶体结构的测定以及与催化性质有密切关系的阳离子交换、扩散、吸附等重要性质的研究所必须。在通常的条件下获得大而完美的沸石单晶体是困难的。单晶的合成,有利于研究沸石晶体的形成与生长机理,是沸石结晶动力学研究的重要课题之一。     

Nanosized Pd assembled on superparamagnetic core–shell microspheres:Synthesis,characterization and recyclable catalytic properties for the Heck reaction

A series of magnetically recyclable Pd/Fe3O4@g-Al2O3 catalysts were synthesized using the superparamagnetic Fe3O4@g-Al2O3core–shell microspheres as the supporter and nano-Pd particles assembled on g-Al2O3 shell as the active catalytic component.The structure of the catalysts was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),N2adsorption–desorption and vibrating sample magnetometer(VSM).The catalytic activity and the recyclability properties of the catalysts for the Heck coupling reaction with aryl bromides and the olefins were investigated.The results show that the microspheres of the magnetic Pd/Fe3O4@g-Al2O3 catalysts were about 400 nm and the nano-Pd particles assembled on g-Al2O3 shell were about 3–4 nm in size.The saturation magnetization(MS) of the magnetic catalysts was sufficiently high to allow magnetic separations.In the Heck coupling reactions,the magnetic Pd/Fe3O4@g-Al2O3 catalysts exhibited good catalytic activity and recyclability.With Pd/Fe3O4@g-Al2O3(0.021 mol%) catalyst,the bromobenzene conversion and product yield reached about 96.8% and 91.2%,respectively,at 120 8C and in 14 h.After being recycled for six times,the conversion of bromobenzene and the recovery of the catalyst were about80% and 90%,respectively.The nano-Pd particles were kept well dispersed in the used Pd/Fe3O4@g-Al2O3 catalysts.     

由苯胺二聚体电化学制备聚苯胺的形貌可控性初探

以苯胺二聚体（N-phenyl-p-phenylenediamine）为起始单体,在1 mol·L^-1高氯酸水-乙腈混合液中,玻碳电极表面电化学制备聚苯胺. 实验结果表明,苯胺二聚体单体的聚合电位比苯胺单体的低约0.2 V,并且其聚合物具有更高的形貌可控性. 苯胺二聚体单体浓度分别为1、5和10 mmol·L^-1时,采用分步恒电流法可分别制备出形貌均一的聚苯胺纳米粒子（粒径30 nm）、超长的纳米线（> 5 μm 直径50 nm）和大面积纳米片（4 μm × 2 μm × 30 nm）.     

Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10~(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1％ (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1％ HNO_3(3.0 mL/min). A good precision(1.6％ for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h~(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.     

氧化反应对胜利褐煤水蒸气气化反应的促进作用Ⅰ:宏观反应特性研究

在φ80×3 000mm耐高温不锈钢管气流床反应器中,以150-180μm胜利褐煤为气化原料,考察了800和900℃时添加氧气前后褐煤转化率的变化,研究了氧化反应对水蒸气气化反应影响的宏观特征。结果表明,添加氧气后褐煤转化率明显大于O_2和H_2O气氛下褐煤转化率之和,即向水蒸气气氛添加氧气后褐煤转化率的增幅大于氧气氧化作用导致的褐煤转化率的增幅,随着H_2O含量增大以及温度的升高此现象愈加明显。该协同作用主要是氧化反应对水蒸气气化反应的促进作用造成的。利用φ40×200 mm石英圆筒流化床反应器进行了类似的实验,也发现了该协同作用。同时,借鉴收缩核模型并结合气流床气化实验条件推导了水蒸气气化宏观动力学方程,得到的速率方程(Z-(1-x))~(1/3)=(tβk_(H_2O)/Rρ_C)φ_(H_2O)=K_(H_2Oφ_(H_2O))与实验值吻合较好,添加氧气后水蒸气气化反应速率和水蒸气气化反应表观速率常数K_(H_2O)明显增大,这是氧气对水蒸气气化反应促进作用的动力学特征。     

Sol-gel Derived Silicate Phosphor Films

Mn²⁺-doped Zn₂SiO₄ and Mg₂Gd₈(SiO₄)₆O₂ phosphor films were deposited on silicon and quartz glass substrates by sol-gel process (dip-coating). The results of XRD and IR showed that the Zn₂SiO₄:Mn films remained amorphous below 700℃ and crystallized completely around 1000℃ From AFM studies, it was observed that the grains with 0.5-0.8 μm size packed closely in Zn₂SiO₄:Mn films, which were uniform and crack free. The luminescence properties of Zn₂SiO₄:Mn films were characterized by absorption, excitation and emission spectra as well as luminescence decay. These properties were, discussed in detail by a comparison with those of Mn²⁺ (and Pb²⁺)-doped Mg₂Gd₈(SiO₄)₆O₂ phosphor films.     

微乳液相色谱法同时分离7种水溶性维生素

采用微乳液相色谱法同时分离7种水溶性维生素(V_(B1)、V_(B2)、V_(B6)、VB_(12)、叶酸、烟酰胺和VC)。考察了微乳流动相体系中表面活性剂、油相、助表面活性剂的种类以及流动相的pH值、柱温等对水溶性维生素分离的影响。优化后微乳体系的组成为:十二烷基硫酸钠(SDS)/聚氧乙烯月桂醇醚(Brij35)/正丁醇/乙酸乙酯/水(质量比为2∶60∶66∶8∶864)。色谱柱为Agilent TC C18(250 mm×4.6 mm,5μm),柱温为30℃,检测波长为254 nm,流速为0.5mL/min。7种水溶性维生素在20 min内达到基线分离。在4~36 mg/L范围内,7种水溶性维生素的质量浓度与峰面积的相关系数均大于0.999 1。不同添加水平下,V_(B1)、V_(B2)、V_(B6)、VC和烟酰胺的平均回收率为93.9%~102.9%。该方法可用于食品和药品中的多种水溶性维生素的分离、鉴别及快速测定。     

单晶CaSO4纳米管的制备——非片状结构化合物形成纳米管的新途径

以Ti-O-Ti油酸偶合体作为结构引导生长剂,采用溶剂热技术成功地制备了单晶无水硫酸钙纳米管,并通过XRD、X射线能谱(EDX)、TEM、选区电子衍射(CBED)对CaSO₄纳米管进行了表征.其晶格常数与JCPDS标准卡单斜相CaSO₄晶体数值一致,属P3m1(164)空间群.纳米管呈均匀的直管形,直径约为30nm,内径约为10nm,长度达到3.0μm.并对硫酸钙纳米管的形成机理进行了浅析,提出了非片状结构的离子晶体,通过结构引导生长剂诱导生长成为片状结构,在溶剂热条件下弯曲、旋转、卷拢形成纳米管的新方法.     

在MA(甲基胺)-SiO2-H2O凝胶中ZSM-39单晶的生长

ZSM-39合成专利首次发表于1981年。1982年Schleker和Meier等通过拟合X射线粉末衍射数据推测出ZSM-39晶体具有氧化硅12面体及16面体的笼形包络物结构(ClathrateStructure),与天然矿物硫方晶石(Melanophlogite)的结构类型相近。1983年Bibhy等研究了ZSM-39的性质并用包络物结构进行解释。目前,这类材料的合成与结构研究已成为沸石科学家和矿物学家感兴趣的问题之一。     

在(TPA)2O-Na2O-SiO2-H2O体系中MFI型硅沸石的结晶行为(Ⅱ)──硅沸石微细晶粒的低温合成及其结构和性质表征

以白炭黑和硅溶胶为桂源, 在(TPA)₂O-Na₂O-SiO₂－H₂O体系60℃下合成了高结晶度纯相硅佛石.由SEM测得其晶粒尺寸为0.2μm和0.45μm, 用XRD线宽法测得的为0.02μm.与180℃时合成的硅沸石样品相比, 低温合成的细晶粒硅沸石已具备纳米级材料的若干特性.其正乙烷吸附量反常增大;XRD、FTIR、²⁹SiMASNMR和TG／DTG／DTA的研究证明, 其结构破坏温度和单斜／正交对称性相转变温度明显下降, 桂羟基缺陷明显增加.