A new molecular rectifier device and some research in its processing

Organic materials of D-π-A type MR-X (MR-1: p-dimethylaminophenylethenetrica-rbonitrile and MR-2: p-diphenylaminophenylethene tricarbonitrile) were designed and synthesized. The device with a sandwich structure shows good rectificative phenomena. The highest rectification ratio 10000 was achieved in device Cu/MR-1/Ag, and about 100 in other device M/MR-X/M (M: Cu, Ag). It has been found that rectificative phenomena exist only in the atmosphere-liquid interface region by means of liquid adsorption, and electric field could help form the oriented molecular film. __________ Translated from Journal of Fudan University (Natural Science), 2005, 44(4) (in Chinese)     

超高效液相色谱-串联质谱法对饲料中15种β-肾上腺素能激动剂的测定

动物源性食品中兽药残留是近几年来国际社会开始研究的公共卫生问题之一.世界各国加强了对国际贸易动物源性食品中兽药残留的检测,而开展饲料及饲料添加剂中兽药残留的检测是从源头进行控制的有效手段[1].     

Preparation, characterization and biocompatibility of poly(ethylene glycol)-poly(n-butyl cyanoacrylate) nanocapsules with oil core via miniemulsion polymerization

A new type of nanocapsules with an oil core, coated by poly(ethylene glycol) (PEG) was designed. The loading efficiency and the biocompatibility of the polymeric nanocapsules were evaluated when it was used as a carrier for hydrophobic agent paclitaxel. The nanocapsules were synthesized through miniemulsion polymerization of butylcyanoacrylate (BCA) with PEG as initiator. The particle size and zeta potential of nanocapsules were influenced by the PEG content in the polymerization system. Fourier transform infrared (FTIR) spectra and ¹H NMR demonstrated the chemical coupling between PEG and poly(butylcyanoacrylate) (PBCA). Thermal characteristics of the copolymer were investigated by differential scanning calorimetry (DSC). The encapsulation efficiency increased concurrently with the increase of the PEG content in the system. The hemolytic assay and the cytotoxicity measurement showed that the PEG coating could significantly reduce the hemolytic potential and cytotoxicity of the nanocapsules. The results showed that the PEG-PBCA nanocapsules could be an effective carrier for hydrophobic agents.     

Micromorphology and phase behavior of cationic polyurethane segmented copolymer modified with hydroxysilane

A series of cationic waterborne polyurethane dispersions (SiPU) modified with hydroxysilane (HPMS) were successfully synthesized based on poly(oxytetramethylene) glycols (PTMG) and isophorone isocyanate (IPDI), and the films were obtained by casting the dispersions on tetrafluoroethylene (TFE) plates. Effects of HPMS content on micromorphology, particle size of the dispersions were studied, as well as thermal properties, phase behavior and surface structure of the films. The particles had the morphology of a solid sphere, with particle size varying from 17.1 nm to 114.4 nm corresponding to the increase of HPMS concentration, which can be attributed to the increase of interfacial tension. XPS spectra indicated the surface migration of Si element in the process of film forming, and the SiPU surface was mainly composed of soft segments. DSC analysis, together with TG-DTG-DTA results demonstrated the HPMS soft segment merged with the transition region of PU matrix, forming part of polyurethane backbone, but an improved microphase separation was observed when HPMS concentration greater than 15%. It was also found that incorporation of flexible HPMS prevented the degradation of polyurethane backbone, resulting in the increase of thermal stability in ultimate copolymer.     

Theoretical studies of blue-emitting iridium complexes with different ancillary ligands

The structural and electronic properties of two heteroleptic iridium complexes Ir(dfppy)2(pic) (FIrpic) and Ir(dfppy)2(acac) (FIracac) have been investigated theoretically, where dfppy = 2-(2,4-difluorophenyl) pyridine, pic = picolinic acid, and acac = acetoylacetonate. The geometries of ground and excited states are optimized at PBE0/LANL2DZ and CIS/LANL2DZ levels, respectively. Time-dependent density functional theory (TDDFT) method is employed to explore the absorption and emission properties. In the ground state, the highest-occupied molecular orbital has a significant mixture of metal Ir(d) and dfppy(pi), the lowest-unoccupied orbital locates primarily on pi* of pic for FIrpic and pi* of dfppy for FIracac. The luminescence of each complex originates from the lowest triplet excited state, which is assigned to the mixing of metal-to-ligand charge transfer and intraligand charge transfer characters. The effects of ancillary ligands pic and acac on absorption and emission spectra are observed by analysis of TDDFT results. The connection between the nature of excited states and the behavior of the complexes with different ancillary ligands is elucidated.     

1:1 Adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid with dimethylammonium and 4,4′‐bipyridine

The title compounds, dimethylammonium 2‐{4‐[1‐(4‐carboxymethoxyphenyl)‐1‐methylethyl]phenoxy}acetate, C₂H₈N⁺·C₁₉H₁₉O₆⁻, (I), and 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid–4,4′‐bipyridine (1/1), C₁₉H₂₀O₆·C₁₀H₈N₂, (II), are 1:1 adducts of 2,2′‐[isopropylidenebis(p‐phenyleneoxy)]diacetic acid (H₂L) with dimethylammonium or 4,4′‐bipyridine. The component ions in (I) are linked by N—H...O, O—H...O and C—H...O hydrogen bonds into continuous two‐dimensional layers parallel to the (001) plane. Adjacent layers are stacked via C—H...O hydrogen bonds into a three‐dimensional network with an –ABAB– alternation of the two‐dimensional layers. In (II), two H₂L molecules, one bipy molecule and two half bipy molecules are linked by O—H...N hydrogen bonds into one‐dimensional chains and rectanglar‐shaped rings. They are assembled viaπ–π stacking interactions and C—H...O hydrogen bonds into an intriguing zero‐dimensional plus one‐dimensional poly(pseudo)rotaxane motif.     

Probing the viscoelastic response of glassy polymer films using atomic force microscopy

The mechanical properties of glassy films and glass surfaces have been studied using an atomic force microscope (AFM) through various imaging modes and measuring methods. In this paper, we discuss the viscoelastic response of a glassy surface probed using an AFM. We analyzed the force-distance curves measured on a glassy film or a glassy surface at temperatures near the glass transition temperature, Tg, using a Burgers model. We found that the material's characteristics of reversible anelastic response and viscous creep can be extracted from a force-distance curve. Anelastic response shifts the repulsive force-distance curve while viscous creep strongly affects the slope of the repulsive force-distance curve. When coupled with capillary force, due to the condensation of a thin layer of liquid film at the tip-surface joint, the anelasticity and viscous creep can alter the curve significantly in the attractive region.     

New method of blood typing using analytical magnetapheresis

We report a new method of blood typing based on the agglutination of red blood cell (RBC) with serum-treated magnetic particles in analytical magnetapheresis. Blood typing of ABO was demonstrated. The agglutination patterns of RBCs are different for different blood types and can be used to determine the ABO blood typing in analytical magnetapheresis. Six samples can be tested in each run. The running time was less than 10 min. Magnetic particles were prepared in the laboratory. The amount of RBCs needed for the agglutination test was about 1.0 microl of adult blood. The blood typing of ABO was used to illustrate the capable applications of analytical magnetapheresis to nonmagnetic samples like cells without magnetic labels. Analytical magnetapheresis has a great potential for cell related analysis.     

Electrochemical behavior and determination of epinephrine at a mercaptoacetic acid self-assembled gold electrode

The electrochemical behavior of epinephrine (EP) at a mercaptoacetic acid (MAA) self-assembled monolayer modified gold electrode was studied. The MAA/Au electrode is demonstrated to promote the electrochemical response of epinephrine by cyclic voltammetry. The possible reaction mechanism is also discussed. The diffusion coefficient D of EP is 6.85 × 10⁻⁶ cm² s⁻¹. In 0.1 mol L⁻¹ phosphate buffer (pH 7.20), a sensitive oxidation peak was observed at 0.177 V, and the peak current is proportional to the concentration of EP in the range of 1.0 × 10⁻⁵–2.0 × 10⁻⁴ mol L⁻¹ and 1.0 × 10⁻⁷–1.0 × 10⁻⁶ mol L⁻¹. The detection limit is 5 × 10⁻⁸ mol L⁻¹. The modified electrode is highly stable and can be applied to the determination of EP in practical injection samples. The method is simple, quick, sensitive and accurate.     

Al-Zn-Mg-Cu合金双级时效析出行为的TEM研究

Al-Zn-Mg-Cu合金是一种时效强化高强变形铝合金,长期以来广泛应用于航空航天等工业领域[1,2].其性能主要由时效过程中的时效析出相决定.研究不同时效状态下合金时效析出相的显微组织结构,对明确组织与性能的关系、确定合理的热处理工艺、改善合金的综合性能具有重要的理论意义和工程实用价值.