Stabilization of metastable tetragonal zirconia nanocrystallites by surface modification

Metastable tetragonal zirconia nanocrystallites were studied in humid air and in water at room temperature (RT). A stabilizing effect of different surfactants on the tetragonal phase was observed. Furthermore, the phase stability of silanized metastable tetragonal zirconia nanocrystallites was tested by prolonged boiling in water. The samples were analyzed with X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Changes in the monoclinic volume fraction in the samples were calculated. A number of surfactants were screened for their ability to stabilize the tetragonal phase upon exposure to humidity. Only silanes and phosphate esters of these were able to stabilize the tetragonal phase in water. Even as small amounts of silanes as 0.25 silane molecule per nm2 are able to stabilize the tetragonal phase in water at RT. Aminopropyl trimethoxy silane and γ-methacryloxypropyl trimethoxy silane were even capable of preventing phase transformation during boiling for 48 h in water

Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean – potential impacts

Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates), natural (desert dust, sea salt) and chemically aged (sulphate and nitrate on dust) aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode) are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment). The sodium (sea salt related) aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region

Technical Note: Anthropogenic and natural offline emissions and the online EMissions and dry DEPosition submodel EMDEP of the Modular Earth Submodel system (MESSy)

International audienceWe present the online calculated Earth's surface trace gas and aerosol emissions and dry deposition in the Modular Earth Submodel System (MESSy) submodel EMDEP as well as the currently applied anthropogenic and natural emissions inventories. These inventories, being read-in by the MESSy submodel OFFLEM, include the industrial, fossil fuel, agricultural and biomass burning emissions considering emission height profiles as a function of the source category based on the EDGAR v3.2 fast track 2000 inventory. Terrestrial and marine emissions of a selection of trace gases and aerosols are calculated online in EMDEP using climate model parameters such as wind speed, temperature and land cover and land use parameters. The online dry deposition calculation includes gases and aerosols, where the default selection for the trace gases for the dry deposition scheme can be easily extended using a commonly applied method based on trace gas solubility and reactivity. In general, the simulated global annual emissions agree with previously reported inventories, although differences exist, partly dependent on the applied model resolution. A high sensitivity of the simulated dry deposition to the applied emission height profiles stresses the importance of a realistic and consistent representation of the spatial and temporal variability in surface exchange processes in Earth system models

The impact of model grid zooming on tracer transport in the 1999/2000 Arctic polar vortex

International audienceWe have used a 3D chemistry transport model to evaluate the transport of HF and CH4 in the stratosphere during the Arctic winter of 1999/2000. Several model experiments were carried out with the use of a zoom algorithm to investigate the effect of different horizontal resolutions. Balloon-borne and satellite-borne observations of HF and CH4 were used to test the model. In addition, air mass descent rates within the polar vortex were calculated and compared to observations. Outside the vortex the model results agree well with the observations, but inside the vortex the model underestimates the observed vertical gradient in HF and CH4, even when the highest available resolution (1°×1°) is applied. The calculated diabatic descent rates agree with observations above potential temperature levels of 450 K. These model results suggest that too strong mixing through the vortex edge could be a plausible cause for the model discrepancies, associated with the calculated mass fluxes, although other reasons are also discussed. Based on our model experiments we conclude that a global 6°×9° resolution is too coarse to represent the polar vortex, whereas the higher resolutions, 3°×2° and 1°×1°, yield similar results, even with a 6°×9° resolution in the tropical region

О параллельной обработке потока данных, адаптированной к области бит произвольной конфигурации

Предлагается модель операции свёртки арифметических многорядных двоичных кодов (МРК), которая учитывает неравномерность распределения бит данных по разрядам. На основе этой модели разрабатываются процедуры и методы свёртки МРК, которые позволяют снизить задержку на обработку.Пропонується модель операції згортки арифметичних багаторядних двійкових кодів (БРК), яка зважає на нерівномірність розподілу біт даних за разрядами. На основі цієї моделі розроблюються процедури і методи згортки БРК, які дозволяють зменшити затримку на обробку.Model of the compressing operation of arithmetic multi-row binary codes (MRC) is offered. In this model irregularity allocation of data bit per digits is considered. Procedures and methods of compressing MRC based on this model allow diminish delay of processing are designed (developed)

The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere

International audienceThe new Modular Earth Submodel System (MESSy) describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model version up to 0.01 hPa was used at T42 resolution (~2.8 latitude and longitude) to simulate the lower and middle atmosphere. The model meteorology has been tested to check the influence of the changes to ECHAM5 and the radiation interactions with the new representation of atmospheric composition. A Newtonian relaxation technique was applied in the tropospheric part of the domain to weakly nudge the model towards the analysed meteorology during the period 1998?2005. It is shown that the tropospheric wave forcing of the stratosphere in the model suffices to reproduce the Quasi-Biennial Oscillation and major stratospheric warming events leading e.g. to the vortex split over Antarctica in 2002. Characteristic features such as dehydration and denitrification caused by the sedimentation of polar stratospheric cloud particles and ozone depletion during winter and spring are simulated accurately, although ozone loss in the lower polar stratosphere is slightly underestimated. The model realistically simulates stratosphere-troposphere exchange processes as indicated by comparisons with satellite and in situ measurements. The evaluation of tropospheric chemistry presented here focuses on the distributions of ozone, hydroxyl radicals, carbon monoxide and reactive nitrogen compounds. In spite of minor shortcomings, mostly related to the relatively coarse T42 resolution and the neglect of interannual changes in biomass burning emissions, the main characteristics of the trace gas distributions are generally reproduced well. The MESSy submodels and the ECHAM5/MESSy1 model output are available through the internet on request

Veilige toegang en verantwoord delen: psychologische determinanten van veilig wachtwoordgedrag en het veilig online delen van persoonsgegevens. KCPEG onderzoeksrapport in opdracht van WODC

Social decision makin

Functionalized cyclophellitols are selective glucocerebrosidase inhibitors and induce a bona fide neuropathic Gaucher model in zebrafish

Gaucher disease is caused by inherited deficiency in glucocerebrosidase (GBA, a retaining β-glucosidase), and deficiency in GBA constitutes the largest known genetic risk factor for Parkinson's disease. In the past, animal models of Gaucher disease have been generated by treatment with the mechanism-based GBA inhibitors, conduritol B epoxide (CBE), and cyclophellitol. Both compounds, however, also target other retaining glycosidases, rendering generation and interpretation of such chemical knockout models complicated. Here we demonstrate that cyclophellitol derivatives carrying a bulky hydrophobic substituent at C8 are potent and selective GBA inhibitors and that an unambiguous Gaucher animal model can be readily generated by treatment of zebrafish with these