The preparation of a new polysiloxane copolymer with glucosylthioureylene groups on the side chains

A new polysiloxane with pendent sugar units was prepared by a two-step method: the preparation of the polysiloxane with amino groups on the side chain and then the copolysiloxane reacted with glucosyl isothiocyanate. All polymers were characterized by FT-IR 1H-NMR, 1H-1H-COSY, 13C-NMR, and DEPT respectively. In the same time, Platinum oxide was found to be a versatile and powerful hydrosilation catalyst in the hydrosilylation reaction of aminotrimethylenepolysiloxanes with heptamethylcyclotetrasiloxane (D₄^H).     

Electrochemical determination of 6-mercaptopurine at silver microdisk electrodes

The electrochemical behaviour of 6-mercaptopurine (6-MP) at a microdisk electrode is investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that 6-MP can be strongly adsorbed on the surface of the static mercury drop electrode (SMDE) and reacts with Ag+ ions which are produced at positive potentials. 6-MP yields a well-defined cathodic stripping signal during the negative scan at about -0.812 V (vs. SCE) in pH 9.0 phosphate buffer solution. The electrode has hence been used for the determination of 6-MP by differential pulse voltammetry (DPV). The linear range is between 2.0x10(-7) and 5.0x10(-5) mol/l, with the calculated detection limit (S/N=3) of 8.0x10(-8) mol/l. The relative standard deviation is 3.0% for eight successive determinations of 4.0x10(-5) mol/l 6-MP. The determination of 6-MP in tablets has also been carried out and satisfactory results have been obtained.     

一种加成固化型热固性树脂PN-PAA固化过程和热稳定性研究

研究了炔丙基醚化酚醛树脂(PN)与聚芳基乙炔树脂(PAA)的反应性共混物(以下简称PN-PAA共混树脂)的相容性,并对共混树脂的固化过程和固化物的耐热性进行了表征.相态、DSC、SEM、TEM等测试结果均表明共混树脂及其固化物是完全相容的均相体系.凝胶时间、粘度、DSC等结果表明共混树脂固化工艺性优良,适合多种成型工艺(如RTM),显著改善了PAA树脂的固化工艺缺陷.DMA、TGA等分析表明共混树脂固化物具有很高的耐热性,可作为新型的防热复合材料和高温结构材料的基体.     

Facile hydrothermal construction of Nb_2CT_x/Nb_2O_5 as a hybrid anode material for high-performance Li-ion batteries

Herein,a simple yet efficient hydrothermal strategy is developed to in-situ convert multi-layered niobium-based MXene(Nb_2 CT_x) to hierarchical Nb2 CTx/Nb_2O_5 composite.In the hybrid,the Nb_2O_5 nanorods are well dispersed in and/or on the Nb_2 CTx.Thanks to the synergetic contributions from the high capacity of Nb_2O_5 and superb electrical conductivity of the two-dimensional Nb_2 CT_x itself,the resultant Nb_2 CTx/Nb_2O_5 hybrid exhibits excellent rate behaviors and stable long-term cycling behaviors,when evaluated as anodes for Li-ion batteries.     

Surface plasmon resonance and electrochemistry for detection of small molecules using catalyzed deposition of metal ions on gold substrate

Small molecules are difficult to detect by conventional surface plasmon resonance (SPR) spectroscopy due to the fact that the changes in the refractive index resulted from the binding process of small biomolecules are quite small. Here, we report a simple and effective method to detect small biomolecule using SPR spectroscopy and electrochemistry by catalyzed deposition of metal ions on SPR gold film. As an example, the ascorbic acid-mediated deposition of Ag on gold film was monitored by in situ SPR spectrum. The deposition of Ag atom on gold film resulted in an obvious decrease of depth in SPR angular scan curves of reflectance intensity and minimum reflectivity angle. The depth change of the SPR reflectance intensity and minimum reflectivity angle curves mainly relied on the amount of Ag atom deposited on gold film that can be controlled by the concentration of ascorbic acid. By monitoring the deposition of Ag atom on gold film, ascorbic acid was detected in the concentration range of 2 × 10⁻⁵ M to 1 ×  10⁻³ M. After each of detections, the SPR sensor surface was completely regenerated by a potential step that stripped off the Ag atom. Furthermore, the regeneration process of the sensor surface provides the feasibility for detecting the concentration of ascorbic acid by electrochemical method.     

Growth control of homogeneous pulsed electrodeposited Co thin films on n-doped Si(1 1 1) substrates

Cobalt thin films were deposited by pulsed electrodeposition on n-doped silicon substrates. We show that the morphology and the magnetic properties of the samples can be controlled by a careful choice of the deposition conditions. Atomic force microscopy measurements reveal a granular growth with grain size and homogeneity strongly dependent on the total deposition time and pulse frequency of the applied signal. Magnetic force microscopy and magnetization measurements indicate the formation of magnetically correlated grain systems with a maximum magnetic correlation and homogeneity for samples with grain diameters of about 40 nm.     

Intrinsic infrared absorption for carbon–fluorine bonding in fluorinated nanodiamond

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Polyelectrolytes-organometallic multilayers for efficient photocurrent generation: [polypropylviologen/RuL2(NCS)2/(PEDOT;PSS)]n on ITO

The polyelectrolytes-organometallic system is prepared and applied to the photocurrent generation. The viologen-containing polymers (polyproylviologen) have two Br⁻ counter ions and are easily soluble in water. The viologen-containing polyelectrolyte multilayers were formed by layer-by-layer deposition method. And as a photosensitizer, RuL₂ (CNS)₂ are easily incorporated in the multilayer films by a ion-exchange method. The energy levels of LUMO of RuL₂(CNS)₂, viologen, and ITO are well arranged and form an acceptor–sensitizer system. The photocurrent measurement of the systems shows excellent photocurrent generation: 1200 nA/cm² under A.M 1.5 condition for 4.5 bilayers sample.     

Growth and characterization of Mn- and Co-doped ZnO nanowires

A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect of Cobalt(II) (1,10-phenanthroline)₃ complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10⁻⁹–3.0 × 10⁻⁷ g mL⁻¹ range with a detection limit of 4.4 × 10⁻¹⁰ g mL⁻¹ cobalt(II). The relative standard deviation for the determination of 5.0 × 10⁻⁸ g mL⁻¹ of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II) in pharmaceutical preparations.     

Total synthesis of (+)-(S)-angustureine and the determination of the absolute configuration of the natural product angustureine

Angustureine, isolated from the bark of Galipea officinalis Hancock, is a novel quinoline alkaloid with a n-pentyl side chain at the 2-position. The total synthesis of (+)-(S)-angustureine and a determination of the absolute configuration of the natural product angustureine were achieved using ring-closing metathesis (RCM) and the Mitsunobu reaction as key steps.