Preparation and performance of a novel polyimide foam

A new type of polyimide foam (PIF) was prepared and characterized based on a one‐pot process by the reaction of a first solution with different ratios of a second solution. The first solution was comprised of pyromellitic dianhydride (PMDA), N, N‐dimethyl formamide (DMF), methanol, water, surfactant, and catalysts, while the second solution contained polyaryl polymethylene isocyanate (PAPI). In the present study, the relationships among compositions, structures, and properties of PIFs were investigated. The results indicated that with the increase in the weight ratio of PAPI/(first solution), the foaming degrees of PIFs increased from 10.14 to 10.52 times and the apparent densities before postcure decreased from 15.96 to 14.51 kg/m³. The open cell contents, average sound absorption coefficients, and average cellular diameters of PIFs after postcure increased with increase in the weight ratio of PAPI/(first solution). The glass transition temperatures (T_g) of PIFs after postcure first increased from 287 to 299°C, then decreased to 292°C, and the 5% weight loss temperatures and 10% weight loss temperatures presented the same trend as well. The compressive and flatwise tensile properties scaled very well with the relative densities of the foams after postcure, with the highest compressive strength of 0.03 MPa and the highest flatwise tensile strength of 0.15 MPa. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and properties of two novel copolymers based on squaraine and fluorene units for solar cell materials

Two novel copolymers based on squaraine and fluorine units have been synthesized through palladium catalyzed Suzuki coupling reaction and Sonogashira coupling reaction,respectively.The structures and properties of the two copolymers were characterized by FT-IR.NMR,UV-vis absorbance（Abs）,gel permeation chromatography（GPC）,thermal gravimetric analysis （TGA）,differential scanning calorimetry（DSC） and cyclic voltammetry（CV）.The solution absorption spectrums of P₁ and P₂ show two distinct absorption bands,one locates at 300-500 nm and the other at 600-800 nm.The absorption spectrums of P₁ and P₂ in films are broadened obviously and the spectral responses are extended up to 900 nm.Thermal gravimetric analysis demonstrates that the polymers are stable.Cyclic voltammetry experiment shows that the band gaps of the copolymers are 1.65 eV and 1.67 eV. respectively,suggesting their potential for applications as solar cells materials.     

流动分析-离子选择电极法测定水中痕量氟化物

基于流动分析-离子选择电极技术,建立了一种测定水中痕量氟化物的分析方法。体系使用注射泵将注入的样品推出,在稳态的条件下进行测定。样品与总离子强度缓冲溶液(TISAB)等体积混合后,采用蠕动泵注入样品,注入量为400"L。采用注射泵驱动载流速度快,比蠕动泵效果好。载流为0.05mg/L F-标准溶液,采用奥立龙(Orion)电极,倾斜20°的喷壁型(Wall-jet)流通池。样品之间插入清洗,方法没有交叉携出。在最佳的条件下,方法的线性范围为0.05～1.0mg/L,检出限为0.015mg/L,RSD为1.5%(0.2mg/L)。样品分析频率为30样/h。本方法对质控样品的测定结果令人满意。3个水样的加标回收率为96.8%～104.5%。用4个水样与国标中的手工分析方法进行了对比,在95%的置信区间内,配对t检验结果无显著差异。本方法灵敏度高,分析速度快、试剂消耗少,废液排放量低,适用于水中低浓度样品的分析。     

Gold nanoparticle-based colorimetric sensor for studying the interactions of β-amyloid peptide with metallic ions

In this paper, a kind of β-amyloid peptide (Aβ1-16) conjugated gold nanoparticles (Aβ1-16@GNPs) are prepared and employed as colorimetric indicator for studying the interaction of β-amyloid peptide with metallic ions (e.g. Zn²⁺ and Ca²⁺). In the presence of Zn²⁺, mono-dispersing Aβ1-16@GNPs enable to form aggregates or attach on the SHG-44 (human glioma cell) cellular surface which results in significant color change of the solution. The experimental results indicate that Zn²⁺ can interact with Aβ1-16 and form Zn²⁺-β-amyloid peptide complexes. In particular, in the presence of Zn²⁺, a time-dependent interaction of cells with Aβ1-16@GNPs has been observed that may suggest different expression levels of β-amyloid peptide related proteins in various cell cycles. In addition, the aggregating/binding process can be easily reversed by adding EDTA, a good chelated ligand of Zn²⁺, which gives further proof of the interaction mechanism.     

UiO-66-NH2负载铜催化剂的制备及其对醇的催化氧化

通过溶剂热法成功制备了一种基于金属有机骨架(MOF)的复合材料Cu-Cu₂O/UiO-66-NH₂，采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)对材料进行全面表征。在空气作氧化剂条件下，以苯甲醇氧化为苯甲醛作为模型反应，系统地考察了溶剂、温度、催化剂各组分用量等因素对催化效果的影响。研究结果表明，该复合催化剂在醇选择性氧化反应中表现出优异的催化性能，60℃下反应5 h便可将苯甲醇定量转化为苯甲醛，并对其他苄基醇、烯丙基醇和杂芳基醇等底物也展现出良好活性。此外，循环利用3次后，该催化剂活性几乎不变，表明其具有良好的稳定性和重复使用性。     

Sonochemical synthesis of CH3NH3PbI3 perovskite ultrafine nanocrystal sensitizers for solar energy applications

The organic–inorganic hybrid perovskite CH₃NH₃PbI₃ is becoming an interesting material in the field of energy harvesting. This material is one of the cleanest and cheapest components in solar cells which is available in ample amounts. However, most of the previous research work was done on thin film of this material. In the present work we describe the preparation of a powder containing nanoparticles of CH₃NH₃PbI₃ using a sonochemical method. Characterization of the product was done by various methods, such as HRTEM, FTIR, PL, DLS and XRD. The particles were found to be highly crystalline (tetragonal crystal structure), polygonal in shape and having diameters of 10–40 nm.     

A controllable resistor and its applications in pole-zero tracking frequency compensation methods for LDOs

unit-gain compensation ceil and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor.Their advantages and limitations are discussed and verified by simulation results.     

Investigation on cell biocompatible behaviors of polyaniline film fabricated via electroless surface polymerization

Considering for the potential application in tissue engineering, polyaniline (PANi) film was fabricated via a two-step route: a self-assembled monolayer of C₆H₅NHC₃H₆Si(OMe)₃ was firstly formed on the single-crystal Si substrate; the conducting PANi film was then prepared through electroless surface polymerization of the aniline molecules on the aniline monolayer-bearing silane surface in an acidic aqueous solution. The formation of PANi film on Si surface was confirmed by characterizations of X-ray photoelectron spectroscope (XPS) and specular reflectance Fourier transform infrared (SR-FTIR) spectrum, etc. At last, the proliferation behaviors of PC-12 cells on the PANi film surface were studied by the [3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) colorimetric assays, acridine orange fluorometric staining, and scanning electron microscope (SEM) observation, etc. The results demonstrate that the as-prepared PANi film provides high ability for cell proliferation, exhibiting promising potentials as surface coating to cultivate neuronal cells for applications in the tissue engineering.