Chlorinated volatile organic compounds (CVOCs) are toxic chemical entities emitted invariably from stationary thermal operations when a trace of chlorine is present. Replacing the high-temperature destruction operations of these compounds with catalytic oxidation has led to the formulation of various potent metal oxides catalysts; among them are ceria-based materials. Guided by recent experimental measurements, this study theoretically investigates the initial steps operating in the interactions of ceria surface CeO2(111) with three CVOC model compounds, namely chloroethene (CE), chloroethane (CA) and chlorobenzene (CB). We find that, the CeO2(111) surface mediates fission of the carbon–chlorine bonds in the CE, CA and CB molecules via modest reaction barriers. As a result of localization of excess electrons left behind after creation of oxygen vacancies, analogous fission over an oxygen vacant surface systematically necessitates lower energy barriers. Dehydrochlorination of CE and CA molecules preferentially proceeds via a dissociative addition route; however, subsequent desorption of vinyl and ethyl moieties requires less energy than surface assisted β C–H bond breakage. The profound stability of hydrocarbon species on the surface contributes to the observed deactivation of ceria at temperatures as low as 580 K under pyrolytic conditions. Adsorption of an oxygen molecule at an oxygen vacant site initiates decomposition of the adsorbed phenyl moiety. Likewise, adsorbed surface hydroxyl groups serve as the hydrogen source in the observed conversion of CB into benzene. A plausible mechanism for the formation of 1,4-dichlorobenzene incorporates abstraction of a para hydrogen in the CB molecule by an O− surface anion followed by chlorine transfer from the surface. Plotted conversion–temperature profiles via a simplified kinetic model against corresponding experimental profiles exhibit a reasonable agreement. The results from this study could be useful in the ongoing efforts to improve ceria's catalytic capacity for destroying CVOCs.
Communication is a vital process that needs much more understanding and mutual background knowledge on the part of ESL learners in terms of grammar, meaning and context. Thus, the main aim of the current research paper is to identify and figure out the denotative and connotative meaning of barnyard verbs in English and practically analyzing these verbs to identify the dictionary meaning from connotative one. The main problem of this study is attributed to the fact that ESL learners may not be able to identify and understand the connotative meaning of barnyard verbs since these verbs are onomatopoeic (i.e,) a word that phonetically imitates, or suggests the source of sound that it describes). Consider the following example: the verb "coo" ha
... Show MoreThis contribution investigates the effect of the addition of the Hubbard U parameter on the electronic structural and mechanical properties of cubic (C-type) lanthanide sesquioxides (Ln2O3). Calculated Bader's charges confirm the ionic character of Lnsingle bondO bonds in the C-type Ln2O3. Estimated structural parameters (i.e., lattice constants) coincide with analogous experimental values. The calculated band gaps energies at the Ueff of 5 eV for these compounds exhibit a non-metallic character and Ueff of 6.5 eV reproduces the analogous experimental band gap of cerium sesquioxide Ce2O3. We have thoroughly investigated the effect of the O/Ce ratios and the effect of hafnium (Hf) and zirconium (Zr) dopants on the reduction energies of C
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BN Rashid, Ajes: Asian Journal of English Studies, 2013
Background : The number of primary hip arthroplasty is growing with every passing year. At present this surgical operation has no equal in the rate of yielding good results. Despite the fact that in many cases in the long term after surgery radiolucent lines around the cup are observed, the clinical outcomes remain satisfactory.Aim of the study :To study the clinical and radiological manifestations of the aseptic loosening of the endoprosthesisMethods: This is a prospective study based on an analysis of diagnostic findings of 51 patients with aseptic loosening of hip joint components, aged 30 to 84 years. We depend for diagnosis of a septic losing by both clinical evaluation and X-ray assessment Results:The majority of clinical and
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There were signs of the first civilization known to humanity for more than 6000 years BC in the north of Iraq have disappeared this civilization to appear after 500 years in southern Iraq, the Sumerian civilization, which was considered as the opinion of scientists or civilizations, exceeds the impact to Asia and the countries that had been in contact (Sumerians) and see them today in other towns and villages. In subsequent periods of time appeared distinct personalities to their nature, religious, social, special clothing with clothes seem especially long. And usually dress is made from raw wool material making them in the Sumerian era. Put the garment on the body and leaves the top of the right shoulder with the survival of an ope
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النشاطات العلمية لفرع الفكر السياسي
The current study included the collection of 175 samples of blood (Urea-blood) of patients with rheumatoid arthritis from Al–Al-Kindy Teaching Hospital, Baghdad Teaching Hospital and Al-Imamian Al-Kadhimyain Medical City in Baghdad from both sexes with different ages at the period between 1/10/2016-1/2/2017. Bacterial growth results showed that 80% of urea for bacterial transplantation were positive results, while the number of samples showing no bacterial growth was 20%. The bacterial isolation evaluate for morphological testes and biochemical microscopy, as well as identification by Api system. The highest frequency of inflectional bacteria was E. coli (41.97%), followed by E. cloacae (21.25%), P. aeruginosa (12.5%), Salmonella (10%), K
... Show MoreCatalytic removal of the S-content from thiophene is a central step in efforts aiming to reduce the environmental burdens of transportation fuels. In this contribution, we investigate the hydrodesulfurization (HDS) mechanisms of thiophene (C4H4S) over γ-Mo2N catalyst by means of density functional theory (DFT) calculations. The thiophene molecule preferentially adsorbs in a flat mode over 3-fold fcc nitrogen hollow sites. The HDS mechanism may potentially proceed either unimolecularly (direct desulfurization) or via H-assisted reactions (hydrogenation). Due to a sizable activation barrier required for the first Csingle bondS bond scission of 54.6 kcal/mol, we predict that the direct desulfurization to contribute rather very insignificant
... Show MoreObjectives: study the relation between the effect of time (long time duration) with high concentration of iodine
and study its effect on the activity of the thyroid gland (hormonal and histological changes).
Methodology: An experimental study was done on (30) albino rats (8 weeks of age) to know the effect of high
concentration of iodine on the activity of the thyroid gland (hormonal and histological changes) related with
time. The study last for six months for the period of 1/2/2007 to 31/7/2007, the experiment was carried out in the
research lab. of pathology department, College of Medicine, University of Baghdad.
Results: The study shows changes in hormonal levels of thyroid hormones (T3 & T4) and also histologic