Mn和Mg对Al-5Fe合金初生Al3Fe相形貌的影响

Mn和Mg添加到Al-5Fe(质量分数，％，下同)合金中，初生Al3Fe相的形貌发生明显变化．未加入合金元素时，该合金中的初生Al3Fe相长成粗大的针片状；加入2．5％Mn和0．1％Mg(质量分数，下同)后，粗大的初生富铁相消失，取而代之的是细小针状、粒状和花朵状；加入2．5％Mn和1．5％Mg，合金中的富铁相大部分转变为粒状和穗状(分叉状)两种．探讨了粒状和穗状的形成机理．对合金力学性能的测试表明，加入Mn和Mg后，合金的抗拉强度得到了不同程度的提高：Al～5Fe合金为107MPa，Al-5Fe-2．5Mn-0．1Mg合金为139MPa，Al-5Fle-2．5Mn-1．5Mg合金为122MPa，增长幅度分别为29．9％和14％．     

Isothermal oxidation behavior of FeCo–2V intermetallic alloy

Isothermal oxidation behavior and the nature of oxide layer formed during oxidation of FeCo–2V alloy were characterized in the temperature range of 500–600 °C. Oxidation kinetics of the alloy follows a parabolic rate law. SEM and XRD studies indicate the formation of an iron rich outer oxide layer and an inner solute rich layer containing cobalt and vanadium rich oxides. The oxidation mechanism of the FeCo–2V alloy is similar to that of low alloy steels. During the initial stages, preferential oxidation of iron and cobalt occurs at the alloy surface and leads to the formation of a solute rich inner layer. Continued oxidation occurs through oxidation of iron and cobalt at the outer layer and internal oxidation of inner layer. The iron rich oxide layer formed at the surface on oxidation of FeCo alloy is semi-conducting in nature and may not provide the necessary insulating barrier required at the surface to minimize eddy current losses during A.C. applications.     

添加0.1 mass%Y的K38G高温合金1000℃恒温氧化行为

研究了添加0.1mass%稀土Y的铸造K38G高温合金在1000℃的恒温氧化行为.结果表明,较之不含Y的合金,含Y铸态K38G合金的氧化速率显著降低; 氧化时形成双层的外氧化膜,表层为以Cr2O3和TiO.2为主的混合氧化物层,内层为连续的Al2O3层;没有内氧化和内氮化,没有氧化膜的剥落,加入稀土Y有效地提高了氧化膜的粘附性能.     

精制马抗H5N1禽流感病毒免疫球蛋白疏水层析方法的优化

目的对精制马抗H5N1禽流感病毒免疫球蛋白疏水层析方法进行优化。方法将胃蛋白酶直接加入制备好的高效价马抗H5N1禽流感病毒血清进行消化裂解,再加入饱和度为26%的硫酸铵溶液,盐析沉淀离心一次后,直接进行疏水层析进一步纯化F(ab′)2抗体。结果连续洗脱依次出现6个蛋白峰,50min左右,洗脱峰3开始出现,其中含大部分F(ab′)2抗体,此时硫酸铵摩尔浓度约为1.0～1.1mol/L。阶段梯度洗脱,当硫酸铵摩尔浓度降至1.0mol/L时,大量F(ab′)2片段被洗脱下来,纯度达90%以上。结论优化了精制马抗H5N1禽流感病毒免疫球蛋白的疏水层析方法,降低了硫酸铵用量,减少了离心次数,生产周期也大大缩短。     

Synthesis and Characterization of MRI-Detectable Magnetic Dendritic Nanocarriers

Magnetic nanoparticles have been proposed for use as biomedical purposes to a large extent for several years. In this paper we discuss the preparation and characterization of superparamagnetic iron oxide (Fe₃O₄) nanoparticles (SPIONs) coated with acetyled – PAMAM dendrimers(Ac-PAMAM). Also, in the present study, the conjugate (Ac-PAMAM)/SPIO nanoparticles were exhaustivly studied as controlled-release systems for parenteral administration of a model drug 5-aminosalicyclic acid (mesalamine) and analyzed using various release kinetic studies. The nanoparticles thus synthesized have been characterized by a Fourier Transform Infrared (FTIR) spectrophotometer and with X-ray diffraction. The morphology of these nanoparticles was studied by scanning electron microscopy (SEM).     

Energetic and entropic contributions controlling the sorption of benzene in zeolites

The energetic and entropic contributions controlling the sorption of benzene on acidic (H/ZSM-5) and non-acidic (Silicalite-1) MFI type materials were studied using gravimetry, calorimetry and in situ IR spectroscopy to follow the qualitative and quantitative interactions of benzene with the pores and the functional SiOH and SiOHAl groups. The model derived to describe the sorption isotherms indicates the presence of sterically constrained sorption structures for benzene in MFI type materials. The interaction of benzene with the pore walls controls the sorption energetically, while the localized interaction with the bridging hydroxy groups contributes only to a minor degree. If benzene is located close to SiOHAl groups perturbed hydroxy groups are formed. Their wavenumber reflects the local sorption geometry of benzene as well as the acid strength of the hydroxy group and the base strength of benzene. Two perturbed hydroxy groups were observed for benzene adsorbed, which are assigned to two orientations of the molecules inside the pores, i.e., with the ring parallel to the pore wall and with the ring being oriented towards the bridging hydroxy groups. At higher coverage benzene adsorbs at SiOHAl groups additionally in an unconstrained environment, most probably at the pore openings.     

这套磷酸装置中P2O5回收率何以如此低下

分析了一套M AP生产装置中磷酸工序P2O5回收率超常低下的原因,并提出改进意见。     

Elaboration and characterization of magnesium-substituted La5Ni19 hydride forming alloys as active materials for negative electrode in Ni-MH battery

The crystallographic structure as well as the thermodynamic and electrochemical properties of the hydrogen absorbing compounds La₅Ni₁₉ and La₄MgNi₁₉ have been determined. X-ray diffraction and microprobe analysis have shown the presence of a single hexagonal (P6₃/mmc) phase for the Mg-free binary compound whereas only one composition but two different crystallographic structures, hexagonal (P6₃/mmc) and rhombohedral (R-3m), are observed for La₄MgNi₁₉. Each phase can be described as the stacking along the c-axis of n[A₂B₄]/m[AB₅] sub-units with n = 1 and m = 3 and A = La, Mg; B = Ni. Depending on the stacking sequence, either the hexagonal or the rhombohedral phase is obtained. Thermodynamic properties toward hydrogen uptake (capacity and equilibrium pressure) and electrochemical properties (cycling behavior) in alkaline medium have been measured and are compared for these compounds with and without magnesium. It is observed that the Mg-free compound exhibits a much lower reversible hydrogen capacity than the Mg-containing one. However, despite larger capacity, this latter compound remains to be optimized in term of cycle life.     

Lean selective catalytic reduction of NO2 by methane over Co‐zeolites

The reaction of NO₂, CH₄ and O₂ was studied using low levels of methane compared to NO₂ and O₂ over protonic and cobalt‐exchanged ferrierite, ZSM‐5 and mordenite zeolites. Results suggest that two reaction pathways at low and high temperatures may be involved in the lean selective catalytic reduction (SCR) of NO₂ by methane. At low temperatures, the reduction of NO₂ to NO and N₂ might be the initial reaction step. It is likely that NO₂ or its adsorbed precursors initiate the reaction of methane at low temperatures. At high temperatures, the oxidation of NO and combustion of methane with oxygen might be involved. No appreciable differences were observed in the reduction of NO₂ over Co‐zeolites as compared to known results of NO reduction over these materials. However, enhanced N₂ formation rate was observed on H‐zeolites starting from NO₂ instead of data reported for NO. Furthermore, it appears that the active sites for SCR are both acid and metal sites. This revised version was published online in July 2006 with corrections to the Cover Date.     

How oxide carriers affect the reactivity of V2O5 catalysts in the oxidative dehydrogenation of propane

The catalytic pattern of several oxide carriers (MgO, Al₂O₃, ZrO₂, TiO₂, SiO₂, HY zeolite) and supported V₂O₅ (4.7–5.3 wt%) catalysts in the oxidative dehydrogenation of propane to propylene (PODH) has been comparatively investigated. The fundamental role of the oxide support on both reducibility and reactivity of vanadia catalysts has been assessed. A direct relationship between the specific surface activity of oxide carriers and that of vanadia catalysts is discussed. The inverse relationship between the specific activity and the onset temperature of reduction marks the prevailing redox behaviour of V₂O₅ catalysts in the PODH reaction. This revised version was published online in July 2006 with corrections to the Cover Date.