水泥混凝土桥面铺装层水损害的成因及防治

针对水泥混凝土桥面的桥面沥青混凝土铺装中,由于压实度不足,在使用过程中极易出现水损害的现象,结合沿海高速公路射阳河桥面铺装的实际应用效果,提出桥面沥青混合料单独进行配合比设计,使沥青混合料具有易压实的特点,以适应桥面铺装的需要,保证铺装层的密实度。     

Adsorptive removal of methyl orange using mesoporous maghemite

In this work, mesoporous maghemite (γ-Fe₂O₃) was prepared by the thermal decomposition of [Fe(CON₂H₄)₆](NO₃)₃ with the aid of cetyltrimethyl ammonium bromide (CTAB), and its adsorption ability for the removal of methyl orange (MO) from wastewater was investigated. X-Ray powder diffraction (XRD) together with nitrogen adsorption–desorption measurements show the formation of mesoporous γ-Fe₂O₃ with an average pore size of 3.5 nm and a specific surface area of 93.0 m²/g. Magnetic measurements show that the mesoporous γ-Fe₂O₃ exhibits ferrimagnetic characteristics with the coercivity of 141.5 Oe and remanent magnetization of 7.3 emu/g and has the maximum saturation magnetization of 55.2 emu/g. The adsorption of MO on the mesoporous γ-Fe₂O₃ reaches the maximum adsorbed percentage of ca. 90% within a few minutes, showing that most of MO can be removed in a short time when the mesoporous γ-Fe₂O₃ is used as an adsorbent. When the pH of MO solution is varied from 3 to 11, the adsorbed percentage of MO decreases from ca. 90 to ca. 81%, showing that the adsorption is slightly influenced by solution pH. The adsorption data for MO fit well with either Langmuir or Freundlich adsorption models. The maximum adsorption capacity of the mesoporous γ-Fe₂O₃ for MO is determined to be 385 mg/g, which suggests that the material could be an excellent magnetic adsorbent for MO.     

Type 1 Cu structure of blue nitrite reductase from Alcaligenes xylosoxidans GIFU 1051 at 2.05 A resolution: comparison of blue and green nitrite reductases

The crystal structure of the blue nitrite reductase from Alcaligenes xylosoxidans GIFU 1051 (AxgNIR) has been determined at 2.05 A resolution. AxgNIR contains both type 1 and 2 Cu sites, the geometry of the former being distorted tetrahedral. The superpositioning of the type 1 Cu sites in the blue enzyme and a green nitrite reductase revealed that the orientation of the Met150 side chain differed. The deviation of the Sdelta(Met150) atom from the axial position of the NNS plane formed by two Ndelta(His95 and His145) and one Sgamma(Cys136) atom caused the difference in the colors of the enzymes, i.e. blue and green.     

硝酸铁直接热分解制备γ—Fe2O3纳米粒子及其性能术

以硝酸铁为原料,三乙二醇（TEG）为溶剂,采用热分解法制备了γ-Fe2O3纳米粒子,通过X射线衍射fXRD）、差热-热重分析、N2吸附-脱附（BET）和磁性分析（VSM）等测试手段对制备的样品进行表征,并考察了硝酸铁浓度和反应时间对γ-Fe2O3晶粒尺寸及性能的影响,结果表明,硝酸铁在TEG中高温热分解后能够产生γ-Fe2O3纳米粒子,并且随着硝酸铁浓度和反应时间的增加,γ-Fe2O3纳米粒子的晶粒尺寸和饱和磁化强度都有增大的趋势。