Synthesis of monodisperse nanocrystalline 8 mol-% yttria doped ceria powder by oleate complex route

Abstract

Preparation of monodisperse nanocrystalline yttria doped ceria powder by the oleate complex route has been reported. Y(III) and Ce(III) oleate complexes have been prepared by the reaction between YCl₃, Ce(NO₃)₃ and sodium oleate at the interface of hexane rich and water rich conjugate layers of water-ethanol-hexane ternary liquid system. Cubic yttria doped ceria crystallises when the waxy solid containing Y(III) oleate and Ce(III) oleate complexes was heat treated at 400°C. The powder after planetary ball milling contains monodisperse near spherical particles of 0·2?μm. These particles contain monodisperse nanocrystallites of size <10?nm. The yttria doped ceria powder pellets were sintered to >98% theoretical density at 1450°C. The sintered ceramic showed an ionic conductivity of 0·0623?S?cm^?1 at 800°C and activation energy of 1·0?eV.     

Determination of elemental composition of cement powder by Spark Induced Breakdown Spectroscopy

Measurement of the cement powder composition as a major building material is considered very important. In this paper the capabilities of Spark Induced Breakdown Spectroscopy (SIBS) as a new technique for analysis of cement powder are shown. The major and minor elements of cement such as Ca, Si, Fe, K, Mg, Al, Na, Ba, Ti, V, Pb, Mn and Sr are detected qualitatively. For quantitative measurement, calibration curves are prepared for elements Ca, Si, Mg, Al, Fe and K with limit of detection below 220 ppm. The critical problems such as how to achieve quantitative measurement and improve the detection limits are investigated. The potential and drawbacks of SIBS technique in comparison with XRF for analysis of powder products are discussed.     

聚氯乙烯粉末涂料

叙述了ＰＶＣ粉末涂料的特性和用途,并举实例说明其生产配方与加工应用技术。     

气相氧化铝提高粉末涂料流动性作用的探讨

简单介绍了气相氧化铝的物性、影响粉末涂料流动性的因素,探讨了气相氧化铝能提高粉末涂料流动性的机理。     

埋粉烧结对BaTiO3陶瓷性能的影响

将自制的水热法BaTiO3粉体干压成形后,分别进行无埋料烧结、Al2O3粉体做埋料烧结和母体BaTiO3粉体做埋料烧结,对烧结后陶瓷体的致密度、显微结构及介电性能进行了分析.结果表明:埋粉烧结对BaTiO3陶瓷体的性能产生显著影响;BaTiO3粉体做埋料时得到的瓷体密度高、晶粒小、电性能优良.     

N,N-二甲基甘氨酸的合成研究

本文报道了合成N,N-二甲基甘氨酸的新方法。以甘氨酸为原料,Pd/C为催化剂,采用常温常压氢化方法,产物收率达95%。     

Characterization of the granular packing and percolation threshold of reactive powder concrete

Reactive powder concrete (RPC) is a new cement-based material developed through microstructural engineering. RPC is composed of very fine powders: sand, crushed quartz and silica fume, all with particle sizes comprised between 300 and 0.02 μm, and a low water content, W/C<0.20. A very dense matrix is achieved by optimizing the granular packing of these powders. This compactness confers to RPC ultrahigh strength and durability.

The hydration kinetic of the cementitious matrix using electrical conductivity and isothermal calorimetry is presented. A linear relationship between the logarithm of conductivity ln(σ) and the degree of hydration , has been found:

ln(σ)=A_v−B_v

where A_v depends on the nature and the dosage of the different mineral and organic components, and B_v is an invariant related to the granular packing. From 19 different RPC compositions, an average value of 12.1 with a standard deviation of 1.7 were found for B_v. The capillary porosity percolation threshold was also deduced from this relationship. It has been found that when the degree of hydration is equal to 26%, the capillary pore space is discontinuous. This last result is in agreement with the prediction of the NIST microstructural model by Bentz and Garboczi [D., Bentz, E. Garboczi, Percolation of phases in a three-dimensional cement paste microstructural model, Cem Concr Res 21 (2) (1991) 325–344]. A continuous determination of the degree of hydration based on electrical conductivity is proposed.     

Combining magnetic nanoparticle with biotinylated nanobodies for rapid and sensitive detection of influenza H3N2

Our objective is to develop a rapid and sensitive assay based on magnetic beads to detect the concentration of influenza H3N2. The possibility of using variable domain heavy-chain antibodies (nanobody) as diagnostic tools for influenza H3N2 was investigated. A healthy camel was immunized with inactivated influenza H3N2. A nanobody library of 8 × 10⁸ clones was constructed and phage displayed. After three successive biopanning steps, H3N2-specific nanobodies were successfully isolated, expressed in Escherichia coli, and purified. Sequence analysis of the nanobodies revealed that we possessed four classes of nanobodies against H3N2. Two nanobodies were further used to prepare our rapid diagnostic kit. Biotinylated nanobody was effectively immobilized onto the surface of streptavidin magnetic beads. The modified magnetic beads with nanobody capture specifically influenza H3N2 and can still be recognized by nanobodies conjugated to horseradish peroxidase (HRP) conjugates. Under optimized conditions, the present immunoassay exhibited a relatively high sensitive detection with a limit of 50 ng/mL. In conclusion, by combining magnetic beads with specific nanobodies, this assay provides a promising influenza detection assay to develop a potential rapid, sensitive, and low-cost diagnostic tool to screen for influenza infections.     

Adsorption of nile red by poly(N‐isopropylacrylamide) gels in binary water/tetrahydrofuran mixtures

The adsorption of Nile Red by poly(N‐isopropylacrylamide) (PNIPAM) gels in binary water/tetrahydrofuran solutions was investigated using absorption spectrophotometry as a function of the volume fraction of THF, φ. Due to the cononsolvency abilities of such binary solvent mixtures, deswelling of the PNIPAM gels is observed in water‐rich mixtures, 0 ≤ φ ≤ 0.6, while the gels reswell for φ > 0.6. The position of the absorption band of Nile Red before and after equilibration with the PNIPAM gels indicates that the composition of the external solvent mixture is not practically influenced by the swelling process. On the other hand, it is found that the gels can effectively adsorb Nile Red in water‐rich mixtures (φ < 0.6), whereas no significant adsorption was observed in tetrahydrofuran‐rich mixtures. In fact, about 80% of the dye is adsorbed by the PNIPAM gels, at φ = 0.2. Under these conditions, the rather shrunk PNIPAM gel offers a more convenient less polar environment for Nile Red than the water‐rich bulk solvent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Reduction of NOx over Fe/ZSM-5 catalysts: mechanistic causes of activity differences between alkanes

Fe/ZSM-5 catalysts prepared by sublimation of FeCl₃ onto H/ZSM-5 catalyze the selective reduction of NO_x by hydrocarbons to N₂. The order of the relative rates and N₂ yields obtained with different alkanes reveals a non-trivial chemistry. The maximum yield is lower for propane than for n-butane but about the same for n- and iso-butane. However, at temperatures below this maximum, the N₂ yield is higher for propane and n-butane than for iso-butane. Deposits are formed on the catalyst that contain N atoms in a low-oxidation state which are able to react with NO₂ to form N₂. TPO and FTIR results show that the amount and also the character of the deposits depend on the nature of alkanes. The change of the oxidation state of nitrogen from a high value in NO or NO₂ to a lower value in nitrile and amino groups of the deposit is rationalized by applying mechanistic concepts of organic chemistry, including the Beckmann rearrangement and fragmentation. FTIR spectra and the observed oxygen- and nitrogen-containing compounds by GC-MS are potential clues to the reaction mechanism.