Advanced Materials Research Vols. 631-632

Abstract: Pseudo-living radical polymerization and reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) were reported, utilizing tris-(4-carboxyphenyl)methane (TCOPM) as the thermal iniferter and initiator, respectively. The polymerization of MMA using TCOPM as thermal iniferter possesses pseudo-living characteristics: Mn increases with conversion in a certain range, and the resulted polymer can be used as the macro-initiator for chain extension. The RATRP using TCOPM as the initiator shows linear kinetic plot, linear increase of Mn with conversion and narrow polydispersity indice (PDI) of the resultant polymers. Effects of temperature on both polymerizations were investigated.

Abstract: N,N-dimethyl twelve/fourteen quaternary ammonium DSD acid-1,3,5-triazine derivatives containing three-component were prepared through three-step condensation reaction using inexpensive twelve/fourteen tertiary amines as raw materials. The obtained products were confirmed by UV and IR spectrum. The maximum UV absorptions of 5a-i were in the range of 250-350 nm. The absorption peaks of cis- and trans- isomers were in 272-274 nm and 326-328 nm, respectively. The maximum fluorescence emission peaks of the products located in the range of 428-430 nm. The physical properties of the products were performed by whiteness measurement. The results show that the nine products have obvious effect on the filter paper whiteness. In particular, the product 5e have the best effect on the filter paper whiteness at a concentration of 1.6 (o.w.f %), which the value of whiteness is 96.78.

Abstract: A new type of interpenetrating phase composite was formed by filling 70%-porous open-cell aluminum foam with polyformaldehyde through injection molding process. The results showed that both mechanical properties and tribological behavior of composites were improved. The interphase behaviour of aluminum foam/polyformaldehyde composites was examined by scanning electron microscopy(SEM).The worn surfaces of composites were also examined and discussed. It could be indicated that injection molding and Al foam surface preprocessing including both alkaline wash and KH550 treatment for Al foam/ POM composites was available. The new composite could be used where moderate strength and wear properties are needed.

Abstract: In the condition of 1.24 mmol/L EDTANa₂, 16.7 mmol/L NaCl and 0.17 mmol/L Tris, the substrate chain of double-stranded DNA (dsDNA) could be cracked by Pb²⁺ to release single-stranded DNA (ssDNA) that adsorb onto AuPd nanoparticle (AuPdNP) and form stable AuPdNP-ssDNA, but the dsDNA can not protect AuPdNP that were aggregated to big AuPdNP aggregations (AuPdNPA) under the action of NaCl. The AuPdNP-ssDNA and AuPdNPA could be separated by centrifugation. With the concentration of Pb²⁺ increased, the released ssDNA increased, the AuPdNP-ssDNA in centrifugation solution increased and the catalytic effect enhanced on the fluorescence quenching reaction of Rhodamine 6G (Rh6G) and NaH₂PO₂, which led the fluorescence intensity at 552nm to decrease. The decreased fluorescence intensity (ΔF_552nm) was linear to the concentration of Pb²⁺ in the range of 0.33-8.00 nmol/L, a detection limit of 0.21 nmol/L. The proposed method was applied to detect Pb2+ in water samples, with satisfactory results.

Abstract: There are strong forces between phenylenediamine (PPD) and nanogold particle (AuNP) that make the AuNPs aggregation and exhibit a strong resonance Rayleigh scattering (RRS) peak at 368 nm. When there is NO₂-, it reacts with PPD to generate an azo compound. However, there is weak force between AuNP and the azo compound that can’t make the AuNPs aggregation. When concentration of NO₂- increased, the AuNP aggregations become weak that led the RRS peak to decrease. The decreased RRS intensity is linear to NO₂-concentration in the range of 1-25 μmol/L. This method was applied to analysis of water samples with simplicity.

Abstract: The AuRu nanoalloy (GR) which Au/Ru molar ratio of 32:1 was prepared by the sodium borohydride reduction method. In the condition of pH 6.0, the GR was used to label CA125 antibody (Ab) to obtain an immunonanoprobe for CA125 (GRAb). In pH 7.0 citric acid-Na₂HPO₄ buffer solution, GRAb was aggregated nonspecifically to big clusters, which showed a strong resonance Rayleigh scattering (RRS) peak at 278nm. When CA125 was added, GRAb reacted specifically with CA125 and GR dispersive in the solution, which led to the RRS intensity decreased greatly. The decreased RRS intensity was linear to the concentration of CA125 in the range of 1.3-80 U/mL, a detection limit of 0.81 U/mL. The proposed method was applied to detect CA125, with satisfactory results.

Abstract: A nano-structured Ni(II)–baicalein(BA) film is electrodeposited on a multiwall carbon nanotube paste electrode in alkaline solution. The modified electrode shows electrocatalytic activity toward the oxidation of hydroxylamine. Kinetic parameters such as the electron transfer coefficient α, rate constant k_s of the electrode reaction and the catalytic rate constant k_cat of the catalytic reaction are determined. The catalytic currents present linear dependence on the concentration of hydroxylamine from 2.5×10^-6 mol•L^-1 to 4.0×10^-4 mol•L^-1 by amperometry. The detection limit and sensitivity are 6.0×10^-7 mol•L^-1 and 31.2 mA•L•mol^-1, respectively. The modified electrode has been applied to determine hydroxylamine in water samples with satisfactory results.

Abstract: As is known to all, the technology is an effective way to improve the material surface performance. In this paper, Micro-arc spark deposition with stellite 6 alloy as the coating material on SCH13 steel substrates was carried out using high-energy micro-arc process. The microstructure, chemical composition, phase identification and hardness of the deposition layers were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Micro-hardness tester, respectively. Moreover, through high temperature oxidation, the property for the deposition layers of resistance to high temperature oxidation was analyzed systematically. The results show that the coatings were consisted of γ-Co solid solution and chromium carbides. The epitaxial growth coating with columnar grains was achieved by micro-arc spark deposition and the coating of stellite 6 alloy has a good metallurgical combination with the SCH13 steel substrate. After high temperature oxidation at 900°C, the surface film of the deposition layers were mainly consisted of chromium oxides, and the surface oxide film of SCH13 steel was Fe₂O₃ and NiCr₂O₄, the property for the deposition layers of resistance to high temperature oxidation is obviously better than SCH13 steel substrate.

Abstract: Cavitation erosion test of Monel-400 and MonelK-500 alloys was carried out in 3.5% NaCl solution using an ultrasonic induced cavitation facility. The microstructure, composition and mechanism of cavitation erosion were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and induction balance, respectively. The results showed that Monel-400 alloy was single austenitic phase while MonelK-500 alloy contained Ni3Al intermetallics and its improvement in cavitation erosion resistance could be attributed to the higher hardness and density of the grain and twinning boundaries. In a series of 5h cavitation tests, the cumulative mass loss of Monel-400 alloy was 44.5 mg, which was 1.66 times than that of MonelK-500(26.8mg). No apparent incubation period was observed and the damage mechanism was plastic deformation and rupture.