نتایج جستجو برای: surface species

تعداد نتایج: 1154343  

1998
Vassil Boiadjiev W. T. Tysoe

The surface species formed by the reaction of gas-phase dimethylzinc with self-supported alumina pellets are examined by Fourier transform infrared spectroscopy. Dimethylzinc reacts with the surface -OH groups of alumina at room temperature evolving methane and yielding mainly surface Al-O-Zn-CH3 species. A small amount of CH3 species appears to bind to the Lewis acid sites of alumina as well, ...

2001
Jih-Mirn Jehng Israel E. Wachs

The current investigation demonstrates that it is possible to molecularly design supported niobium oxide catalysts with the assistance of molecular characterization methods such as Raman spectroscopy. The formation and location of the surface niobium oxide species are controlled by the surface hydroxyl chemistry, and the surface niobium oxide species are located in the outermost layer of the ca...

G. Azari Takami L. Mehdizadeh Fanid, M. Seidgar

Abstract:  The surface morphology of resting eggs of Anostracan species from East Azerbaijan Province of Iran and that of Artemia urmiana was compared using Scanning Electron Microscopy (SEM). Anostracan fauna of East Azerbaijan temporary pools were determined as follows: Chirocephalus skorikowi (Chirocephalidae), Branchinecta orientalis (Branchinectidae), Streptocephalus torvicornis (Streptoce...

Journal: :The Environmentalist 1990
N Myers

This paper aims to throw light on the mass extinction that is overtaking Earth's species. Using an analytic methodology developed for an earlier partial assessment, it focuses on a series of "hotspot" areas, these being areas that a) feature exceptional concentrations of species with high levels of endemism and b) face exceptional threats of destruction. The paper identifies another 8 such ar...

ژورنال: علوم آب و خاک 2005
حسین سیدالاسلامی, , جهانگیر خواجه علی, , مسعود لطیفیان, ,

Some bioecological aspects of grape leafhopper, Arboridia kermanshah Dlabola, including: the egg distribution under the leaf surface, eggs and nymphs spatial distribution on the vine arms, the adult distribution on three strata of the vine canopy, the adult diel activities and the geographical distribution of this species in Isfahan province were studied. Samplings were done in the 1997. The eg...

2003
Yongsheng Chen Israel E. Wachs

The molecular structures and reactivity of tantalum oxide-supported metal oxide (V2O5, Nb2O5, CrO3, MoO3, WO3, and Re2O7) catalysts were determined by Raman spectroscopy and the methanol oxidation chemical probe reaction, respectively. The metal oxides form a twodimensional surface metal oxide overlayer on the tantalum oxide support. Under ambient conditions, the hydrated surface metal oxide sp...

Journal: :Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 2008
Xiuli Zhang Hong He Hongwei Gao Yunbo Yu

Surface nitrate (NO3(-)) species on the Ag/Al2O3 play an important role in the selective catalytic reduction (SCR) of NOx. In this study, the formation and configuration of surface nitrate NO3(-)(ads) species on Ag/Al2O3 and Al2O3 in the oxidation of NO have been studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calcul...

2007
Toshiharu Makino Mitsuru Inada Ikurou Umezu Kouichi Murakami Yuka Yamada Takaaki Orii M Takata I Umezu A Sugimura

Recently, surface passivated Si nanocrystallites are prepared by pulsed laser ablation (PLA) of Si target in hydrogen gas. Plume analysis during PLA is one of the available methods to clarify a mechanism of surface hydrogenation. We observed plume emission by timeand space-resolved spectroscopy. The dominant species were exited neutral Si atoms and SiH species when the delay time is longer than...

2008
Edward L. Lee Israel E. Wachs

The group 5-7 transition metal oxides (V2O5, CrO3, MoO3, WO3, and Re2O7) were anchored on a surface modified SiO2 support containing surface alumina, zirconia, and titania species prepared via incipient wetness impregnation of soluble precursors and calcination. The molecular and electronic structures of these “multilayered” supported M1Ox/M2Ox/SiO2 catalysts were characterized with in situ Ram...

This study investigates the role of man-made disturbance on on nitrogen and phosphorus nutrient storage by herbaceous species in Gall Oak stands of Lorestan province. In order to do this study, two sites with the same physiographic and ecological conditions and different land uses were selected. Multiscale sampling plots were used randomly in each site to collect data on forest floor vegetation...

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