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71.
Matthew J. Watson Helen M. Chan Martin P. Harmer Hugo S. Caram 《Journal of the American Ceramic Society》1998,81(8):2053-2060
The reaction-bonded aluminum oxide process begins with aluminum, Al2 O3 , and usually ZrO2 powders that have been attrition-milled in an organic liquid. The attrition-milled powder is then compacted and heat-treated in air to produce polycrystalline, Al2 O3 -based ceramics. Safety considerations have made it desirable for the milling liquid to be changed from acetone to a less-flammable solvent. In this paper, mineral spirits, ethanol, and mineral spirits that contains 2 wt% stearic acid are presented as viable alternatives to acetone. The effects of changing the milling liquid on the reaction process and the properties of the final fired ceramic are investigated. 相似文献
72.
Andrés Aguirre Matías Cabruja Rodolfo Cabrera Florencia Eberhardt Salvador Peirú Hugo G. Menzella Rodolfo M. Rasia 《Journal of the American Oil Chemists' Society》2015,92(1):47-53
Steryl glucosides (SG) are common contaminants in biodiesel that form precipitates, which form and cause problems due to fouling during transport and storage. Therefore, their quantification is necessary to assess the quality of this fuel. The methods currently available for SG analysis require expensive instrumentation, need a previous concentration step by solid‐phase extraction (SPE) or are of limited use for the quantitative assessment. We developed an enzymatic method for SG quantification in biodiesel samples based on the hydrolysis of the glucoside catalyzed by a broadly specific beta glucosidase and the subsequent determination of the glucose released by the reaction. The method is non‐expensive, sensitive and was adapted to 96‐well format fluorescence plate reader, making it useful for the parallel assay of multiple samples. The enzymatic assay presented here represent a valuable tool for both quality control and the development of improved biodiesel production and purification procedures. 相似文献
73.
Quinone emissions from gasoline and diesel motor vehicles 总被引:2,自引:0,他引:2
Jakober CA Riddle SG Robert MA Destaillats H Charles MJ Green PG Kleeman MJ 《Environmental science & technology》2007,41(13):4548-4554
Gas- and particle-phase emissions from gasoline and diesel vehicles operated on chassis dynamometers were collected using annular denuders, quartz filters, and PUF substrates. Quinone species were measured using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization in conjunction with gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry. Nine quinones were observed, ranging from C6 to C16. New species identified in motor vehicle exhaust include methyl-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone (MNQN), and aceanthrenequinone. Gas-phase motor vehicle emissions of quinones are also reported for the first time. Six gas-phase quinones were quantified with emission rates of 2-28 000 microg L(-1) fuel consumed. The most abundant gas-phase quinones were 1,4-benzoquinone (BON) and MNQN. The gas-phase fraction was > or = 69% of quinone mass for light-duty gasoline emissions, and > or = 84% for heavy-duty diesel emissions. Eight particle-phase quinones were observed between 2 and 1600 microg L(-1), with BQN the most abundant species followed by 9,10-phenanthrenequinone and 1,2-naphthoquinone. Current particle-phase quinone measurements agree well with the few available previous results. Further research is needed concerning the gas-particle partitioning behavior of quinones in ambient and combustion source conditions. 相似文献
74.
Gustavo Larsen Edgar Lotero Rubn D. Parra Lucía M. Petkovic Hugo S. Silva Srinivasanallur Raghavan 《Applied Catalysis A: General》1995,130(2):213-226
Palladium supported on sulfated zirconia (PdSZ) has been characterized by the n-butane isomerization reaction in the presence of hydrogen, X-ray absorption spectroscopy (XAS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) of adsorbed carbon monoxide. Catalyst calcination at 873 K followed by hydrogen reduction at 513 K results in the formation of 30–40 Å Pd metal clusters, but the surface can only weakly adsorb CO, though stronger than Pd-free, sulfated zirconia catalysts. In the presence of hydrogen, PdSZ has a lower n-butane isomerization activity than SZ, and the Pd function cannot stabilize the reaction at low H2/n-butane ratios. 相似文献
75.
Florenza Lüder Ripoli Annika Mohr Susanne Conradine Hammer Saskia Willenbrock Marion Hewicker-Trautwein Silvia Hennecke Hugo Murua Escobar Ingo Nolte 《International journal of molecular sciences》2016,17(5)
Mammary neoplasms are the tumors most affecting female dogs and women. Formalin-fixed, paraffin-embedded (FFPE) tissues are an invaluable source of archived biological material. Fresh frozen (FF) tissue is considered ideal for gene expression analysis. However, strategies based on FFPE material offer several advantages. Branched-DNA assays permit a reliable and fast workflow when analyzing gene expression. The aim of this study was to assess the comparability of the branched-DNA assay when analyzing certain gene expression patterns between FF and FFPE samples in canine mammary tumors. RNA was isolated from 109 FFPE samples and from 93 FF samples of different canine mammary tissues. Sixteen (16) target genes (Tp53; Myc; HMGA1; Pik3ca; Mcl1; MAPK3; FOXO3; PTEN; GATA4; PFDN5; HMGB1; MAPK1; BRCA2; BRCA1; HMGA2; and Her2) were analyzed via branched-DNA assay (b-DNA). ACTB, GAPDH, and HPRT1 were used as data normalizers. Overall, the relative gene expression of the two different origins of samples showed an agreement of 63%. Still, care should be taken, as FFPE specimens showed lower expression of the analyzed targets when compared to FF samples. The fact that the gene expression in FFPE proved to be lower than in FF specimens is likely to have been caused by the effect of storage time. ACTB had the best performance as a data normalizer. 相似文献
76.
Zhongxi Chao Yuefa Wang Jana P. Jakobsen Maria Fernandino Hugo A. Jakobsen 《Chemical engineering science》2011,(16):407
The paper presents a multi-fluid Eulerian model derived from binary kinetic theory of granular flows, free path theory and an empirical friction theory. The effects of the inter- and inner-particle collisions, particle translational motions and particle–particle friction are included. As the effects due to fluiddynamic particle velocity differences and particle–particle friction are considered, some unconventional terms are produced compared with the previous models. Model validation using the data from Mathiesen et al. (2000) shows that the coupling terms give a stronger and more realistic particle–particle coupling because the effects due to the fluiddynamic velocity differences are considered. The model gives reasonable predictions of the particle volume fraction, particle velocities and velocity fluctuations. The model analysis reveals that the basic particle velocity fluctuations constitute 2 terms: the velocity fluctuations of the discrete particles, and the velocity fluctuations of the continuous fluid flow. Furthermore, the simulation results show that the velocity fluctuations of the continuous fluid flow are dominant in a binary riser flow. 相似文献
77.
Cuauhtémoc Flores Ferreyra Angel de Jesus Morales Ramirez Hugo Martinez Gutierrez 《腐蚀工程科学与技术》2017,52(3):236-243
This study compares the hot corrosion performance of yttria-stabilised zirconia (7YSZ), and 7YSZ?+?Gd2O3 composite samples in the presence of molten mixture of Na2SO4?+?V2O5 at 1150°C. For 7YSZ, the reaction between NaVO3 and Y2O3 produces YVO4 and leads the transformation of tetragonal ZrO2 to monoclinic ZrO2. A high-density in sintered 7YSZ?+?Gd2O3 samples, led minor amounts of monoclinic ZrO2 and tetragonal GdVO4 as the hot corrosion products with only traceable amounts of YVO4, and a stable corroded layer was formed. Due to the synergic effect of doping of zirconia with Gd2O3, the 7YSZ?+?Gd2O3 sample has a much better hot corrosion crack resistance than 7YSZ. 相似文献
78.
Carina Morando Osvaldo Fornaro Olga Garbellini Hugo Palacio 《Journal of Materials Science: Materials in Electronics》2014,25(8):3440-3447
During last few decades, emerging environmental regulations worldwide, more notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies due to the inherent toxicity of this element. This situation drives to the replacement of the Sn–Pb solder alloy of eutectic composition commonly used as joining material to suitable lead-free solders for microelectronic assembly. Sn-based alloys containing Ag, Cu, Bi, and Zn are potential lead-free solders, usually close to the binary or ternary eutectic composition. For this reason a great effort was directed to establish reliable thermophysical data fundamental to interpret the solidification process and fluidity of alloys belonging to these systems. In this work, an analysis of the solidification process of pure Sn, binary Sn–Ag, Sn–Cu, Sn–Bi, Sn–Zn, Sn–Pb and ternary Sn–Ag–Cu eutectic alloys was carried out using computer aided-cooling curve analysis and differential scanning calorimetry. 相似文献
79.
80.
Regional innovation systems (RSI) concept is an important theoretical framework to analyse regional profiles of regions when trying to understand Innovation but it has also been used by practioners to design and implement policies. This study hopes to contribute to the understanding of the Algarve RSI, a peripheral Portuguese region in the National and European framework, where an economic growth is supported by Tourism, which leaves it out of the group of poorest regions when the GDPpc indicator is taken in account. The regional profile, the comparison with the other European regions and the characterisation of RSI following developed typologies are discussed in this paper. Through the analysis of 175 regions of the EU 15 the study seeks to find the dimensions underlying the innovative phenomena and to create homogeneous groups of regions that display similar profiles. Factorial Analysis was used to reduce the dimension of data from a barrage of regional indicators such as: Critical Mass of Territories, Economic Performance, Level of Wealth, Employment Market, Sectoral Structure of the Economy, Age Group Structure, Education and Training, Technological Employment, R&D and Patents. Having determined the four main factors with significant results (Technological Innovation, Human Capital, Economic Structure and Availability of the Employment Market) what followed was a hierarchical analysis of Clusters, resulting in five groupings of regions: Disadvantaged Regions, Average Regions, Central Regions, Large Economic Centres and Innovating Regions. A synthesis of the recent Regional Innovation Strategies for the Algarve is presented including previous experiences (Ettirse and INOVAlgarve) and the Algarve’s Regional Innovation Plan, which will try to create a pathway for regional development supported by knowledge-based activities for a more diversified regional economy. 相似文献