Concept

Cycle du dioxyde de silicium

Publications associées (85)

Balancing nutrient inputs to Lake Kivu

Alfred Johny Wüest, Beat Mueller, Martin Schmid

The primary production in meromictic Lake Kivu is sustained by external nutrient inputs and by internal loading due to upwelling caused by sub-aquatic sources. We present here the results of external loading of phosphorus (P), nitrogen (N) and silica (Si) ...

Elsevier Sci Ltd2009

Physical and biogeochemical limits to internal nutrient loading of meromictic Lake Kivu

Alfred Johny Wüest, Beat Mueller, Martin Schmid, Bernhard Wehrli

Lake Kivu is one of the large African Rift lakes situated between the Democratic Republic of the Congo and Rwanda. In its permanently stratified hypolimnion, unusually high methane concentrations have increased further in recent decades. Because methanogen ...

Amer Soc Limnology Oceanography2009

Effective Charge of Adsorbed Poly(amidoamine) Dendrimers from Direct Force Measurements

Ramon Pericet Camara, Michal Borkovec

Interaction forces between silica surfaces with adsorbed poly (amidoamine) (PAMAM) dendrimers were measured with the colloidal probe technique based on the atomic force microscope (AFM). At small separations, attractive non-DLVO forces are observed. These ...

American Chemical Society2009

Gold Nanoparticles Supported on Passivated Silica: Access to an Efficient Aerobic Epoxidation Catalyst and the Intrinsic Oxidation Activity of Gold

David Lyndon Emsley, David Benjamin Roger Antoine Gajan

Well-defined and perfectly dispersed [(square SiO)Au(1)] surface species supported on silica have been obtained via surface organometallic chemistry and transformed upon mild reduction (H(2), 300 degrees C) into small (1.8 +/- 0.6 nm) Au particles supporte ...

AMER CHEMICAL SOC2009

Lake Baikal deepwater renewal mystery solved

Alfred Johny Wüest, Martin Schmid

Deepwater renewal by intrusions and turbulent diffusion in Lake Baikal is very effective despite the enormous depth of up to 1642 m and the permanently stable stratification below similar to 300 m depth. Temperature time series recorded at the bottom of a ...

Amer Geophysical Union2008

Optical properties of annealed Mn2+-doped ZnS nanoparticles

Heinrich Hofmann, Alke Fink, Benedikt Steitz, Yvonne Axmann

Cysteine stabilized ZnS and Mn2+-doped ZnS nanoparticles were synthesized by a wet chemical route. Using the ZnS:Mn2+ nanoparticles as seeds, silica-coated ZnS (ZnS@Si) and ZnS:Mn2+ (ZnS:Mn2+@Si) nanocomposites were formed in water by hydrolysis and conden ...

2008

Hierarchical assembly of the siliceous skeletal lattice of the hexactinellid sponge Euplectella aspergillum

Georg Fantner

Despite its inherent mechanical fragility, silica is widely used as a skeletal material in a great diversity of organisms ranging from diatoms and radiolaria to sponges and higher plants. In addition to their micro- and nanoscale structural regularity, man ...

2007

The effect of silica on the degradation of organohalides in granular iron columns

Tamar Kohn

Dissolved silica species are naturally occurring, ubiquitous groundwater constituents with corrosion-inhibiting properties. Their influence on the performance and longevity of iron-based permeable reactive barriers for treatment of organohalides was invest ...

Elsevier2006

Nitrogen and Sulphur Deposition on regional and global scales: a multi-model evaluation

We use 23 atmospheric chemistry transport models to calculate current and future (2030) deposition of reactive nitrogen (NOy, NHx) and sulfate (SOx) to land and ocean surfaces. The models are driven by three emission scenarios: (1) current air quality legi ...

2006

Nanoparticules à noyau métallique recouvert de silice

Heinrich Hofmann, Alke Fink

The invention relates to nanoparticles based on a metal, on a metal alloy or on a metal derivative coated with a silica layer, in which the silica is crystalline silica, in particular crystalline silica in the cristobalite form. They may be prepared from n ...

2006

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