Chemical Research in Chinese Universities最新文献

The non-isothermal degradation kinetics of N,N'-di(diethoxythiophosphoryl)-1,4-phenylenediamine in N₂ was studied by TG-DTG techniques. The kinetic parameters, including the activation energy and pre-exponential factor of the degradation process for the title compound were calculated by means of the Kissinger and Flynn-Wall-Ozawa(FWO) method and the thermal degradation mechanism of the title compound was also studied with the Satava-Sestak methods. The results indicate that the activation energy and pre-exponential factor are 152.61 kJ/mol and 9.06 × 10¹⁴ s^-1 with the Kissinger method and 154.08 kJ/mol with the Flynn-Wall-Ozawa method, respectively. It has been shown that the degradation of the title compound follows a kinetic model of one-dimensional diffusion or parabolic law, the kinetic function is G(α)=α² and the reaction order is n=2.

Four kinds of lanthanide ions(Sm³⁺, Yb³⁺, Eu³⁺, La³⁺) as an additive were added into the aqueous solution containing methanol, respectively, and their effects on methanol elecotrooxidation in aqueous solutions were studied with cyclic voltammetry. The results show that the four kinds of ions have promotion action upon the electrooxidation of methanol to different degrees. The best additive, Sm³⁺, can increase the anodic oxidation current of methanol by 80% and the peak potential shifted negatively about 50 mV. The promotion effects of the lanthanide ions were considered to be related to the extranuclear electron distribution of these ions and their adsorption on the Pt electrode surface.

The reaction of dinaphthofuran with lithium in anhydrous diethyl ether led to a solution of the corresponding C,O-dilithiated intermediate which, upon treatment with DMF at −78°C, afforded, after hydrolysis, 2′-hydroxy-1,1′-binaphthyl-2-carbaldehyde in a good yield. Then binaphthyl-bridged Schiff bases were prepared by the condensation of 2′-hydroxy-1,1′-binaphthyl-2-carbaldehyde with the corresponding aromatic amines.

Binary metal oxide(MnO_x-A/TiO₂) catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide(TiO₂), where, A indicates Fe₂O₃, WO₃, MoO₃, and Cr₂O₃. Their catalytic activity, N₂ selectivity, and SO₂ poisonous tolerance were investigated. The catalytic performance at low temperatures decreased in the following order: Mn-W/TiO₂>Mn-Fe/TiO₂>Mn-Cr/TiO₂>Mn-Mo/TiO₂, whereas the N₂ selectivity decreased in the order: Mn-Fe/TiO₂>Mn-W/TiO₂>Mn-Mo/TiO₂>Mn-Cr/TiO₂. In the presence of 0.01% SO₂ and 6% H₂O, the NO_x conversions in the presence of Mn-W/TiO₂, Mn-Fe/TiO₂, or Mn-Mo/TiO₂ maintain 98.5%, 95.8% and 94.2%, respectively, after 8 h at 120 °C at GHSV 12600 h^-1. As effective promoters, WO₃ and Fe₂O₃ can increase N₂ selectivity and the resistance to SO₂ of MnO_x/TiO₂ significantly. The Fourier transform infrared(FTIR) spectra of NH₃ over WO₃ show the presence of Lewis acid sites. The results suggest that WO₃ is the best promoter of MnO_x/TiO₂, and Mn-W/TiO₂ is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH₃.

Metal-coated fiber Bragg grating(FBG) temperature sensors were prepared via electroless nickel(EN) plating and tin electroplating methods on the surface of normal bare FBG. The surface morphologies of the metal-coated layers were observed under a metallographic microscope. The effects of pretreatment sequence, pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed. Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer. Sensitivity of the metal-coated FBG(MFBG) sensor was almost two times that of normal bare FBG sensor. The measuring temperature of the MFBG sensor could be up to 280 °C, which was much better than that of conventional FBG sensor.

The virus-like particle(VLPs) vaccine is an ideal HIV-1 vaccine, which can simultaneously induce a neutralizing antibody reaction and cell-mediated immunity effectively. In this study, two kinds of plasmids have been used, one can express the HIV-1 main structure proteins, Gagpol and Env, and the other contains an antibiotic gene. The two kinds of plasmids have been cotransfected into 293 cells. A stable cell line that can express Gagpol and Env proteins efficiently and lastingly has been screened. It has been confirmed that Gagpol and Env proteins in the cell culture supernatant can be self-assembled into virus-like particles. The authors have detected the secretion of VLPs in the cell medium, defined the peak of the secretion, and followed and monitored the stability of expression.

Morphologies, crystallization behavior and mechanical properties of polypropylene(PP)/syndiotactic 1,2-polybutadiene(s-1,2 PB) blends were investigated. Morphology observation shows the well dispersed domains of s-1,2 PB in PP matrix with the rather small domain sizes from 0.1 to 0.5 um when the s-1,2 PB content increases from 5% to 20% (mass fraction) in the blends, and the phase structure tends to become co-continuous as s-1,2 PB content further increases. Crystallization temperature(T_c) of PP component in the blends is fluctuated with the variation of s-1,2 PB content in the blends. Compatibilization, to some extent, between the two components is inferred from the examination of both morphology and crystallization behavior. Improvement of impact strength of PP toughened by s-1,2 PB becomes significant only in the case of s-1,2 PB content above 20%(mass fraction).

Mg-doped Ni nanoparticles with good soft magnetic properties were prepared with the sol-gel method and were sintered at 400, 500, 600, and 900 °C in argon atmosphere, respectively. The structure and magnetic properties of the samples were studied by means of X-ray diffraction, TEM, and VSM magnetometers. X-Ray powder diffraction results show that Ni-Mg solid solution was formed with the single phase of face-centered cubic(fcc) structure. The particle size became larger with the increase of temperature. When the sintering temperature was 400 °C, the particle size was 6.3 nm, whereas it was 46.2 nm at 900 °C. Both the saturation magnetization(M_s) and the coercivity were enhanced with the increase of the particle size. The M_s values of the samples ranged from 18.965 to 46.766 emu/g and the coercivity ranged from 1051.3568 to 9145.0848 A/m.

Environmentally friendly biocomposites were prepared by blending wheat gluten(WG) as a matrix, hydroxyethyl cellulose(HEC) as a filler, and glycerol as a plasticizer, followed by thermo-molding of the mixture at 120 °C for crosslinking the matrix. Moisture absorption, tensile properties, dynamic mechanical analysis, and dynamic rheology were evaluated in relation to the glycerol content. Tensile strength and modulus drop dramatically with increasing glycerol content, which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.