Effect of the activation procedure on the performance of Mo/H-MFI catalysts for the non-oxidative conversion of methane to aromatics

The effect of pre-treatment on the performance of Mo/H-MFI zeolite catalysts applied to the non-oxidative conversion of methane to aromatics has been investigated. It is demonstrated that catalyst performance depends on activation conditions. Activation of the Mo-oxide/H-MFI precursor with an n-butane/hydrogen mixture results in higher catalyst stability and benzene selectivity which are tentatively attributed to the formation of the -MoC_1−x carbide, with f.c.c. structure as revealed by XRD.     

“Greening Up” Cross-Coupling Chemistry

New methodologies that enable palladium catalyzed cross-coupling reactions to be performed under environmentally benign conditions (in water and/or at room temperature) have been developed. Described approaches involve in situ activation of carbon–halogen or carbon–hydrogen bonds using zinc metal, or cationic palladium, respectively.     

Aggregation and surface properties of F-specific RNA phages: implication for membrane filtration processes

We report an experimental investigation of the electrokinetic properties and size variations of four F-specific bacteriophages of the types MS2, GA, Qbeta and SP (21-30 nm in diameter) over a broad range of pH values (1.5-7.5) and NaNO3 electrolyte concentrations (1-100 mM). The results obtained by dynamic light scattering show that the aggregation of SP and GA particles takes place over the whole range of pH and ionic strength conditions examined. For MS2 phages, the aggregation of MS2 particles is not observed for pH higher than the isoelectric point (pI) and large ionic strengths for which interparticular repulsive electrostatic interactions are however expected to be sufficiently screened. Aggregation of the MS2 phages, dispersed in 1 and 100 mM electrolyte concentration, occurs at pH 4, which basically corresponds to the pI as determined by electrophoresis measurements. The Qbeta particles suspended in solutions of low electrolyte concentrations aggregate at low pH values (pI approximately 3) and, unlike MS2, at large ionic strengths over the whole range of pH conditions considered in this study. These elements allow the determination of the hydrophobic sequence for the four phages SP approximately GA>Qbeta>MS2. Close inspection of the electrokinetic results reveals small to significant variations of the pI values-depending on the phage considered-with respect to the concentration of indifferent NaNO3 electrolyte. This indicates that features other than chemical and electrostatic in nature play a key role in determining the pI and more generally the electrophoretic mobility mu of viral particles. A qualitative interpretation is given and is based on the consideration of inner electro-osmotic flow within the isolated or aggregated particles. The impact of the flow properties within the particles is further in agreement with recent theoretical formalism developed for the electrokinetics of soft multiplayer particles, the phages analyzed here being some illustrative examples. The determination and qualitative interpretation of the surface properties of the viral particles as reported in the current study are commented within the context of water treatment especially concerning viral removal by membrane filtration processes.     

Atmospheric mercury depletion event study in Ny-Alesund (Svalbard) in spring 2005. Deposition and transformation of Hg in surface snow during springtime

A field campaign was conducted in Ny-Alesund (78 degrees 54'N, 11 degrees 53'E), Svalbard (Norway) during April and May 2005. An Atmospheric Mercury (Hg) Depletion Event (AMDE) was observed from the morning of April 24 until the evening of April 27. Transport of already Hg and ozone (O3) depleted air masses could explain this observed depletion. Due to a snowfall event during the AMDE, surface snow Hg concentrations increased two fold. Hg deposition took place over a short period of time corresponding to 3-4 days. More than 80% of the deposited Hg was estimated to be reemitted back to the atmosphere in the days following the event. During the campaign, we observed night and day variations in surface snow Hg concentrations, which may be the result of gaseous elemental mercury (GEM) oxidation to divalent Hg at the snow/air interface by daylight surface snow chemistry. Finally, a decrease in the reactive Hg (HgR) fraction of total Hg (HgT) in the surface snow was observed during spring. We postulate that the transformation of HgR to a more stable form may occur in Arctic snow during spring.     

Use of a theoretical model to investigate RF and DC reactive sputtering of titanium and chromium oxide coatings

An analysis of RF and DC reactive sputtering techniques is presented. The transition between a metal sputtering mode and a compound sputtering mode is usually noticed with a metallic target and an argon+oxygen gas mixture. The so-called hysteresis effect often observed for small amounts of reactive gas is explained in recent models. By considering gas kinetics parameters, it is possible to evaluate quite simple relationships between the main processing parameters. These theoretical calculations enable the prediction and aid the understanding of instability phenomena observed in reactive sputtering. In this paper, the effects of some parameters on the position and size of instability regions are discussed, and the difference between DC and RF reactive deposition is investigated. Simulations and experimental results are compared for the case of titanium and chromium oxide thin films prepared by DC and RF reactive sputtering. The influence of sputtering power on the position of the hysteresis loop is analysed theoretically and experimentally, and the changes observed between the reactive sputtering of titanium and chromium oxide materials are also discussed.     

Why and how do project management offices change? A structural analysis approach

The growing popularity of Project Management Offices (PMOs) as organizational structures is grounded in the assumption they support more efficient and effective project management for better strategy implementation. However, research emphasizes they fail to deliver expected value: their unstable nature precludes the delivery of long-term benefits. This is compounded by the absence of a theory of PMO change and adaptation. Recent research, taking a co-evolution lens rooted in evolutionary theory, suggests that PMOs should be studied in relation to the broader organizational context, in order to better capture the dynamic interplay and fit between them. In this study, taking a routine perspective as micro-foundation and unit of analysis, we focus on the co-evolution between PMO and Project Portfolio Management (PfM) as organizational capability for six case studies. A structural analysis of the relational routines' system between PMO, PfM and the Organizational context allow us to unveil dynamics at stake, i.e. why and how changes occur, as well as eigen behaviors and the changing states of various routines elements (influential, mediating, dependent or not-influential). This study makes five contributions. We show that: 1) PMO and PfM can be conceptualized as collections of routines, 2) PMO and PfM co-evolve over time to adapt to organizational context influence, 3) the co-evolution of a routines' system, abstracted as a non-trivial machine, exhibits an eigen behavior, 4) applying a structural analysis approach allows to simulate the dynamics of a routines' system and to unveil the role of key routine elements and 5) eigen values of routines' systems allow to characterize their eigen behavior.     

Trace metal concentrations in the North-western Mediterranean atmospheric aerosol between 1986 and 2008: Seasonal patterns and decadal trends

Climatic and anthropogenic changes are able to engender modifications in the aerosol composition at different geographical and temporal scales. The present study addresses this question for the trace metal concentrations (TM = Al, Fe, Mn, Co, Ni, Cu, Pb, Cd and Zn) of aerosol from the North-western Mediterranean coast of France (Cap Ferrat, nearby Nice) between 1986 and 2008. From seasonal variations (2006-08) and decadal trends (1986-2008) of TM concentrations, three groups of elements can be distinguished. They consist of different aerosol sources: crustal-derived elements (Al, Fe, Mn and Co), trace metals of anthropogenic origin (Pb, Cd and Zn) and a third, intermediate, group of trace metals that presented both anthropogenic and natural/crustal influences (Ni and Cu). Reproducible seasonal patterns were observed for crustal and intermediate elements with highest concentrations between May and November, while anthropogenic trace metals did not show a pronounced seasonal cycle. Nevertheless, highest concentrations of anthropogenic trace metals occurred mostly in autumn/winter. Aerosol concentrations of anthropogenic TMs decreased remarkably over the last two decades, while crustal trace metals did not show any evolution. Nickel and copper aerosol concentrations remained constant, as well. Lead concentrations decreased from 1986 (29.34 ng m^− 3) to 2008 (3.33 ng m^− 3), overall by 90%. Cadmium and zinc aerosol concentrations decreased by 66 and 54%, respectively, between 1998 and 2006-08, from 0.27 to 0.09 ng m^− 3 and from 23.9 to 10.9 ng m^− 3, respectively. These findings demonstrate the response of the atmospheric environment to the implementation of antipollution policies. Possible changes of trace metal emissions sources and local influences are discussed.     

Atmospheric particle evolution during a nighttime atmospheric mercury depletion event in sub-Arctic at Kuujjuarapik/Whapmagoostui, Québec, Canada

During a field experiment at Kuujjuarapik/Whapmagoostui (55.31 degrees N, 77.75 degrees W), Quebec, we observed increases of concentrations of particles with diameters larger than 0.3 microm in the ambient air during a nighttime atmospheric mercury depletion event (AMDE). These increases were strongly correlated with decreases of ozone and atmospheric mercury, and we also observed a change in the particle size distribution during this AMDE. Assuming that these phenomena imply either a chemical link or an association through transport, we also studied the nature of this AMDE. We hypothesize that the observed AMDE was a result of an influx of already depleted air masses and that it was not a product of local chemical reactions.     

通过项目执行战略（下）

5原型和项目管理：如何面对复杂性和不确定性的挑战 过去十年期间，项目和大型项目计划管理文献内曾大篇幅报道有关核心战略的问题，但多数都未真正考虑使用一种认识论的方法(Bredillet，2004a)。项目管理分类(Shenhar et al.，2002；Turner．2000；Crawford et al．，2002；2004)也可反映组织理论核心逻辑所反映的趋势(Crawford et al．，2002：NASA，2004)。虽然分类标准和类别之间存在细微的差异，