نتایج جستجو برای: siliceous composition

تعداد نتایج: 260770  

Journal: :Colloids and Surfaces A: Physicochemical and Engineering Aspects 2019

Journal: :International journal of occupational safety and ergonomics : JOSE 1998
Tomasz Ligor Helena Górecka Bogusław Buszewski

A series of siliceous adsorbents with chemically bonded phases (CBPs) of different polarity were tested as sorbents for trapping air pollutants (petroleum ether) using controlled setup. Moreover, special attention was paid to the potential role of metal impurities as strong adsorption sites. Sorbents were characterized by various physico-chemical methods, such as porosimetry, inductively couple...

Journal: :Journal of Physical Chemistry C 2021

Synchrotron X-ray diffraction was used to investigate the insertion of helium in archetypal siliceous zeolite Mobil-Five (MFI). Due very high degree penetration into pores ...

Journal: :Geobiology 2010
E A Sperling J M Robinson D Pisani K J Peterson

The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spic...

Journal: :Journal of structural biology 2009
Mark Hildebrand Sang Kim Dan Shi Keana Scott Sriram Subramaniam

Ion-abrasion scanning electron microscopy (IASEM) takes advantage of focused ion beams to abrade thin sections from the surface of bulk specimens, coupled with SEM to image the surface of each section, enabling 3D reconstructions of subcellular architecture at approximately 30nm resolution. Here, we report the first application of IASEM for imaging a biomineralizing organism, the marine diatom ...

Journal: :The Journal of chemical physics 2008
T P M Goumans C Richard A Catlow Wendy A Brown

The sequential addition of H atoms to CO adsorbed on a siliceous edingtonite surface is studied with an embedded cluster approach, using density functional theory for the quantum mechanical (QM) cluster and a molecular force field for the molecular mechanical (MM) cluster. With this setup, calculated QM/MM adsorption energies are in agreement with previous calculations employing periodic bounda...

Journal: :Journal of environmental quality 2005
Nathan O Nelson John E Parsons Robert L Mikkelsen

Accurate descriptions of P leaching are important because excess P applied to soils can enter surface water via leaching and subsurface transport, thereby negatively impacting water quality. The objectives of this study were to monitor P leaching in soils with a long-term history of waste application, relate soil solution P concentrations to soil P status, and quantify P leaching losses. Soil s...

2012
Peter A. Siver Anne M. Lott

The genus Mallomonas, the largest within the Class Synurophyceae, consists of motile, unicellular, freshwater heterokonts that are covered with an outer layer of overlapping siliceous scales. The scales are flat, circular to oval structures with taxonomically distinct designs. In addition to scales, the cell coverings of most Mallomonas species contain a second siliceous component known as a br...

Journal: :Geobiology 2013
P A Siver A P Wolfe F J Rohlf W Shin B Y Jo

Synurophytes, also known as scaled chrysophytes, are ecologically important algae that produce an array of siliceous structures upon which their taxonomy is based. Despite occupying a key position within the photosynthetic heterokonts, the evolutionary history of synurophytes remains poorly constrained. Here, modern and Middle Eocene siliceous scales of the morphotaxon Mallomonas insignis are u...

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