Advanced Materials Research Vols. 239-242

Abstract: An electrochemical impedance biosensor was proposed for the detection of small molecule biotin based on the plasma-polymerized films (PPF) and the bioaffinity difference between an analyte (biotin) and an analogue compound (HABA) in binding avidin. Avidin formed a metastable complex with 2-[(4-hydroxyphenyl)azo]benzoic acid (HABA) immobilized on the electrode surface. When the sensor contacts a sample solution containing biotin, the avidin was released from the sensor surface to form a more stable complex with biotin in solution. The impedance spectra change recorded is proportional to the desorbed mass of avidin, and there is a clear mathematic relationship between the impedance change and the biotin concentration. The proposed electrochemical impedance bioaffinity sensor has nice response to biotin in the range of 4.8×10^-9–5.6×10^-4 M. The sensor could be regenerated under very mild conditions simply by reimmersion of the sensor into a biotin solution to desorb the surplus avidin.

Abstract: A new photochromic diarylethene compound 1-[2-methyl-3-thienyl]-2-[3, 5-dimethyl-4-isoxazolyl]perfluorocyclopentene (1o), was synthesized and its photochromic and fluorescent properties were investigated. Diarylethene 1o changed the color from colorless to orange upon irraditation with 297 nm UV light, which the absorption maxima were observed at 486 nm in hexane solution. This new photochromic system also showed remarkable fluorescence switching in the solid state. Finally, rewritable optical storage using 1o was performed. The results demonstrated that the compound was very sensitive responding to 633 nm recording laser.

Abstract: The microstructure of the matrix and the interface of co-continuous SiC/Fe-2Cr13 (porous SiC preforms infiltrated with the Fe-2Cr13) composites has been investigated by XRD, EDS attached to SEM. Results showed that the reaction zone between SiC and Fe-2Cr13 includes two sections, which are silicon carbide reaction zone (SRZ) and metal reaction zone (MRZ), the MRZ can be divided two sections, one is the poor chromium zone (PCrZ-MRZ) and the other is rich chromium zone (RCrZ-MRZ). SRZ is mainly composed of Fe₅Si₃, Cr₇C₃, Cr₂₃C₆ and Cr₃Si, and randomly distributed graphite precipitates. RCrZ-MRZ mainly contains Cr₂₃C₆, while PCrZ-MRZ is mostly made up of Fe₂Si.

Abstract: Aqueous oil-modified polyurethane dispersions (PUDs) were synthesized using alcoholysis derivatives of vegetable oil, hydroxyl-terminated polyether, isophorone diisocyanate (IPDI) and dimethylolbutyric acid (DMBA). Alcoholysis was performed in order to insert alcoholysis derivatives, which were used as the polyol composition. The structures of alcoholysis derivatives, polyurethane dispersions and their dry films were confirmed by the Fourier Transform Infrared Spectroscopy (FT-IR) and ¹H Nuclear Magnetic Resonance (¹H-NMR), respectively. The effect of alcoholysis derivatives on the properties of PUD films was investigated. The results show that tack-free time and gloss of PUD films would change with the amount of alcoholysis derivatives. When compared to aqueous polyurethane dispersions, aqueous oil-modified PUDs have shorter tack-free time, higher gloss and tensile strength and lower elongation at broken.

Abstract: Traditional lead brass is gradually prevented from application by many countries’ governments because lead does harm to human health and pollutes the environment. New types of environment-friendly lead-free brass with favorable machinability are urgently demanded in the electrical, electronics and plumping fields. Lead-free Mg-Sb brass was fabricated in present. Experimental results showed that when the content of Mg is 1.0wt%, Sb is 0.8wt% and Cu is 58.0~59.0wt%, the alloy’s mechanical properties and machinability are favorable for industry application. With the increase of the content of Sb, the machinability increased, while the mechanical properties decreased. Lots of Cu₂Mg and Cu₉Sb₂ particles on the order of microns exist in the inner-grain and grain boundaries. These particles improve the machinability, however, lower the tensile strength and the elongation. A three-way pipe joint was successfully punched with the fabricated Mg-Sb brass bar, and this demonstrated that the fabricated Mg-Sb brass possesses favorable hot working property.

Abstract: A new unsymmetrical photochromic diarylethene compound, 1-(2,4-dimethyl-5-thiazolyl)-2-[5-(2-chlorobenzene)-2-methyl-3-thienyl]perfluorocyclopentene(1a), was synthesized and its photochromism and photo-induced anisotropy was investigated. Diarylethene 1a changed the color from colorless to Orange-red upon irradiation with 297 nm UV light, in which absorption maxima were observed at 479 nm in hexane and at 485 nm in PMMA amorphous film, respectively. It also showed good photochromism and functioned as an effective fluorescent photoswitch in solution. In hexane, the open-ring isomer of the diarylethene 1a exhibited relatively strong fluorescence at 428 nm when excited at 315 nm. This new photochromic system also exhibited remarkable optical storage character.

Abstract: Aluminum alloy coatings for pretreatment are developed by sol-gel method. The adhesion between sol-gel film and the paint film was measured by scratching circles and corrosion resistance of sol-gel film was tested by salt spraying experiment. The adhesion between sol-gel film made by pure alumina sol and the paint film was so poor that it is unsuitable for ground coatings, but the composite sol which ultrafine Al₂O₃ powder was added to pure alumina sol can improve the adhesion and corrosion resistance. If the first layer film is made of pure alumina sol and the second layer is made of composite sol, the neutral salt spraying time of double layers film is longer than the single-layer composite sol-gel film. The adhesion for both double composite film and single-layer composite sol-gel film are first-grade. When solution of potessium dichromate is dropped on double combinatorial film for 100s, the solution will change in color. The gloss of paint film on double composite sol-gel film is 0.827, flexibility is 2×10mm and impact resistance is 1kg∙50cm. It is possible that composite sol-gel film or combinatorial sol-gel film replace dichromate salt conversion film on aluminum alloy using for painting pretreatment.

Abstract: Brush plating has been an important technology for the mending of the scratched surface of the engineering parts in recent years.The process for brush plating mending of scratched surface of the Austenite stainless steel parts is introduced in this article.The merits of the technology are discussed.

Abstract: In this work, a visible photocatalytic system containing Eosin Y, multiwalled carbon nanotubes and CuO was prepared. The photocatalytic hydrogen evolution from water over this system was studied using triethanolamine (TEA) as a sacrificial reagent. The results indicated that it was an efficient photocatalyst with an average rate of H₂ evolution of 373 mmol·h^-1·g^-1 during first three hours under visible irradiation.

Abstract: Using tetrabutyl titanate as source, ethanol as solvent, acetic acid as complexing agent, synthesis of titanium dioxide sol was achieved by sol-gel method. A transparent sol aging in air 30min, titanium dioxide films were prepared by using spin coating method. Rhodamine B degradation by TiO₂ photocatalysis was investigated. Study the efficiency of decolorization was influenced by the coating times, heat-treated time, the initial concentration of rhodamine B, and solution pH.