نتایج جستجو برای: surface species

تعداد نتایج: 1154343  

2000
Laura E. Briand William E. Farneth Israel E. Wachs

A detailed study of the methanol chemisorption and oxidation processes on oxide surfaces allowed the development of a method to quantify the number of surface active sites (Ns) of metal oxide catalysts. In situ infrared analysis during methanol adsorption showed that molecular methanol and surface methoxy species are co-adsorbed on an oxide surface at room temperature, but only surface methoxy ...

Journal: :مرتع و آبخیزداری 0
بهزاد رایگانی استادیار دانشکده علوم محیط زیست و منابع طبیعی، دانشگاه محیط زیست غلامرضا زهتابیان استاد دانشکده منابع طبیعی، دانشگاه تهران حسین آذرنیوند دانشیار دانشکده منابع طبیعی، دانشگاه تهران سید جمال الدین خواجه الدین استاد دانشکده منابع طبیعی، دانشگاه صنعتی اصفهان سید کاظم علوی پناه استاد دانشکده جغرافیا، دانشگاه تهران

arid and semi-arid areas, due to the sensitive, have variable ecosystems, so continuous assessment and monitoring of the environment is required for most of managerial and adjustment practices. vegetation is one of the most important assessment tools and used as a criterion for evaluation and monitoring of ecosystem functions. in this study, for the first time in the country, we have evaluated ...

1999
David G. Barton Max Shtein Ryan D. Wilson Stuart L. Soled Enrique Iglesia

UV-visible diffuse reflectance spectroscopy was used to probe the electronic structure and domain size of tungsten oxide species in crystalline isopolytungstates, monoclinic WO3, and dispersed WOx species on ZrO2 surfaces. UV-visible absorption edge analysis, CO2 chemisorption, and Raman spectroscopic results show that three distinct regions of WOx coverage on ZrO2 supports appear with increasi...

2002
Jeffrey Shaman Marc Stieglitz Colin Stark Sylvie Le Blancq Mark Cane

We modeled surface wetness at high resolution, using a dynamic hydrology model, to predict flood and swamp water mosquito abundances. Historical meteorologic data, as well as topographic, soil, and vegetation data, were used to model surface wetness and identify potential fresh and swamp water breeding habitats in two northern New Jersey watersheds. Surface wetness was positively associated wit...

Journal: :Physical chemistry chemical physics : PCCP 2005
Andrew Cheesman Jeremy N Harvey Michael N R Ashfold

Density functional theory-based electronic structure computations on small models of the diamond {100} surface have enabled prediction of the energetics and activation parameters of a number of plausible mechanistic steps for boron incorporation into, and boron loss from, the growing diamond surface. Initial proving calculations for the carbon-only case show, as in previous work, that the rate-...

2001
FRANKLIN D. HARDCASTLE

The interaction of rhenium oxide with an alumina support is examined over a wide range of conditions (rhenium oxide loading, calcination temperature and environment) using laser Raman spectroscopy (LRS) and X-ray absorption near-edge spectroscopy (XANES). These structural probes reveal that supported rhenium oxide on alumina is present as an atomically dispersed surface [ Re04] ads species coor...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ارومیه 1377

the methods which are used to analyze microstrip antennas, are divited into three categories: empirical methods, semi-empirical methods and full-wave analysis. empirical and semi-empirical methods are generally based on some fundamental simplifying assumptions about quality of surface current distribution and substrate thickness. thses simplificatioms cause low accuracy in field evaluation. ful...

2013
Vincenzo Vaiano Diana Sannino Ana Rita Almeida Paolo Ciambelli

In this work, the results of gas phase cyclohexane photocatalytic oxidative dehydrogenation on MoOx/SO4/TiO2 catalysts with DRIFTS analysis are presented. Analysis of products in the gas-phase discharge of a fixed bed photoreactor was coupled with in situ monitoring of the photocatalyst surface during irradiation with an IR probe. An interaction between cyclohexane and surface sulfates was foun...

2005
F. Gao

The chemistry of tributyl phosphate on Fe3O4 was studied in ultrahigh vacuum using temperature-programmed desorption (TPD) and Auger spectroscopy. A portion of the tributyl phosphate desorbs intact with an activation energy of 120 kJ/mol. The remainder decomposes either by PAO bond scission to deposit surface butoxy species or appears to dehydrogenate desorbing C2 or C3 compounds and depositing...

Journal: :The Journal of experimental biology 2014
S P Yanoviak D N Frederick

Upon falling onto the water surface, most terrestrial arthropods helplessly struggle and are quickly eaten by aquatic predators. Exceptions to this outcome mostly occur among riparian taxa that escape by walking or swimming at the water surface. Here we document sustained, directional, neustonic locomotion (i.e. surface swimming) in tropical arboreal ants. We dropped 35 species of ants into nat...

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