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Article
A Deactivation Correlation for Platinum Y-Zeolite in n-Hexane Isomerization

Author: Haiyam Mohammed A. Al-Raheem
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 8 Pages: 1451-1462
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The objective of the present work is to realize the kinetic modeling regardingdeactivation of Pt-HY zeolite and monitor the isomerization reaction of n-hexane. Thecatalyst has been prepared with o.4% Pt and evaluated during the isomerization reactionof n-hexane. Based on the results of catalytic investigation, a kinetic model was proposedto deactivate the catalyst by coke formation. The present method provides information onapparent overall kinetics as well as deactivation parameters and would seem to provide arapid method for screening of reaction/deactivation behavior. Accordingly thedeactivation order was found to be 3.72. The obtained correlation of deactivation predictsthe activity pattern under the applied reaction conditions, closely mimics those observedexperimentally, and spans those obtained from empirical correlations.


Article
The Relation between Type of Ligature and Force Delivered by Orthodontic Arch Wire

Authors: Eman G Mohi-aldin --- Saad S Gasgoos
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2014 Volume: 14 Issue: 24 Pages: 47-51
Publisher: Mosul University جامعة الموصل

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Abstract

This in vitro study aims to compare the deactivation force, delivered as a result of releasingsuperelastic arch wire from 4 mm to 2.5 mm in horizontal direction at the area of right maxillary canineon standard model of teeth, by using three different methods to ligate the wire to the brackets.MATERIALES AND METHODS: Materials of this study include three sets of Synergy brackets0.022P Px 0.028 inch, molar buccal tubes, thirty arch wire , 0.016 inch round preformed arch superelasticnickel-titanium wires, were divided to three groups according to ligation method, the first group wasligated with preformed steel wire ligatures ,the second group with elastic ligatures as o configurationand in third group with elastic ligature as c configuration. The measurements were completed at roomtemperature of 27±5 in dry media by machine designed by college of mechanics engineering /Mosuluniversity and the results were compared among the three methods of ligation. RESULTS: Significantdifference in deactivation forces (p < 0.05) were observed. C configuration elastic ligatures had thehigher mean of deactivation force (332 gm) than either o configuration or steel wire ligatures (268.5gm), (267.9 gm) respectively. CONCLUSIONS: Decreasing the ligation force by using C configurationelastic ligatures to ligate the wire to Synergy bracket is potentially adequate to use at the beginningof leveling and aligning stage of orthodontics that allow the arch wire to generate its force withoutmore missing due to high friction, as occurred by the use of stainless steel wire ligatures or o configurationelastic ligatures.


Article
Strain specificity in antimicrobial activity of non-thermal plasma
الفعالية الضد ميكروبيه للبلازما الغير حرارية على نوعية السلالات

Authors: Hammad R. Humud حمد رحيم حمود --- Maha Adel Mahmood مها عادل محمود --- Wafaa Abd Al-Razaq وفاء عبد الرزاق
Journal: Iraqi Journal of Physics المجلة العراقية للفيزياء ISSN: 20704003 Year: 2013 Volume: 11 Issue: 20 Pages: 110-115
Publisher: Baghdad University جامعة بغداد

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Abstract

Non-thermal (low-temperature) plasma may act as an alternative approach to control superficial wound and skin infections when the effectiveness of chemical agents is weak due to natural pathogen or biofilm resistance. In this paper an atmospheric pressure plasma needle jet device which generates a cold plasma jet is used to measure the effectiveness of plasma treatment against different pathogenic bacteria and to test the individual susceptibility of pathogenic bacteria to non-thermal argon plasma. It is found that, Gram-negative bacteria were more susceptible to plasma treatment than Gram-positive bacteria. For the Gram-negative bacteria Pseudomonas aeruginosa, there were no survivors among the initial 1x108C.F.U (Colony Forming Unit) after a 40 seconds plasma treatment. The susceptibility of Gram-positive bacteria and the Gram-negative bacteria were species and strain specific. Staphylococcus aureus was the most resistant with 4.5 % survival of the initial 2x106C.F.U. after a 40 seconds plasma treatment. According to species, Staphylococcus aureus had a strain-dependent resistance with 39% and 99% reduction from 2x106C.F.U.of the five studied isolates, respectively, whereas, Escherichia coli had a lower resistance with 76% and 99% reduction after 40 seconds.

البلازما غير الحرارية (منخفضة درجة الحرارة) تعد نهجاَ بديلاَ للسيطرة على الجروح السطحية والالتهابات الجلدية عندما يكون تاثيرالعوامل الكيميائية ضعيفا وذلك يعود لطبيعة المسبب المرضي اوبسبب مقاومة الغشاء الحيوي. لقد استخدم هذا البحث جهاز نفث ابرة البلازما الذي يعمل بالضغط الجوي والذي يولد بلازما نفث باردة لقياس فعالية المعاملة بالبلازما ضد الممرضات البكتيريه المختلفه, ولاختبار الحساسية الفردية للممرضات البكتيرية لبلازما الاركون البارد. وقد وجد ان البكتريا السالبة لصبغة غرام اكثر حساسية عند معاملتها بالبلازما من البكتريا الموجبة لصبغة غرام. بالنسبة للبكتريا Pesudomonas aeraginosa السالبة لصبغة غرام لم تبقى بكتريا حيه من اصل نسبة اللقاح البالغ تركيزها 1× 106مستعمره بكتيرية/ مللتر بعد 40 ثانية من المعاملة بالبلازما. أن حساسية البكتريا السالبة والموجبة لصبغة غرام تعتمد على نوع البكتريا ونوع السلالات ضمن نفس النوع من البكتريا، حيث كانت البكتيريا Staphylococcus aureus أكثر مقاومة من بقية الانواع المدروسة حيث كانت نسبة البقاء 4% من أصل 2×106 مستعمرة بكتيرية/ مللتر بعد معاملتها بالبلازما لمدة 40 ثانية. واظهرت السلالات الخمسة لهذه البكتيريا اختلافا في نسبة مقاومتها حيث وصلت نسبة الاختزال لاحدها الى 39% من اصل 2×106 مستعمره بكتيرية/ مللتر بينما اظهرت بكتيريا Escherichia coli مقاومة اقل وصلت الى 76% لاحد السلالات المدروسة.


Article
Parametric Study on Intrinsic Reaction for Straight Run Heavy Naphtha Hydrodesulfurization over CoMo/Al2O3 Catalyst

Authors: Mohammad F. Abid --- Mohammed K. Abdullah --- Salah M. Ali
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 2 Part (A) Engineering Pages: 146-153
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The present study aimed to investigate the intrinsic reaction of hydrodesulfurization (HDS) for a real Straight Run Heavy Naphtha (SRHN) over CoMo-S/Al2O3 catalyst in a fixed- bed reactor. Influence of the process parameters on sulfur removal was investigated by regulating the temperature (T = 320-380 oC), pressure (P = 20 to 35 bar), weight hour space velocity (WHSV = 2.5 to 5.0 h-1) and catalyst average particle size (dp =361 to 3950 μm). Mears and Weisz-Prater criteria were estimated and utilized to validate the intrinsic reaction condition. Operating variables were optimized at (T = 360 oC, P = 30 bars, WHSV = 2.5 h-1, dp= 361 μm) to obtain an optimum sulfur removal of 93.4% under intrinsic reaction conditions. Experimental results showed that % activity of sulfur removal increases to 93.4% as temperature increased to 360oC but it reduces to 90.3% as space velocity increased to 5.0 h-1. Kinetic parameters of the intrinsic reaction rate were estimated and compared with published data. Long-time test was performed on the sulfided catalyst to investigate its activity.


Article
Study of Catalysts Deactivation in Isomerization Process to Produce High Octane Gasoline

Authors: Jabir Sh. Jumaly --- Amel Th. Juber --- Hayam M. Abdul-Raheem --- Khalid A. Sukkar
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2007 Volume: 8 Issue: 3 Pages: 43-48
Publisher: Baghdad University جامعة بغداد

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Abstract

In this study the isomerization of desulfuerized light iraqi petroleum naphtha (Al-Dura Refinery) with boiling point range of 37 to 124 °C , 80.5 API specific gravity and 68.2 octane number has been investigated. Two types of catalysts were prepared (Pt/HX and Pt/SrX) by impregnation of 0.8 wt% Pt on 13X-zeolite. The catalyst activity and selectivity toward isomerization, and catalyst deactivation were investigated.The isomerization unit consisted of a vertical tubular stainless steel reactor of 2 cm internal diameter, 3 cm external diameter and 6 height The operating pressure was atmospheric for all experimental runs. The l(quidflow of light naphtha was 0.4 Lih, and the catalyst weight was 50 gm, H2/H.C ratio used was 4 for all experimental runs. The isomerization process was studied at different temperatures of 250, 270, 275, 300, 325, and 350°C. It was found that, the optimum isomerization temperature is 270°C.The isomerization activities and selectivities as afunction of time showed high activity at the beginning of the reaction and were deactivated rapidly. This indicates that the deactivation of Pt/HX and Pt/SrX results from the blocking of pore mouth by the deposited carbon. The following deactivation decreasing order, Pt/HX> Pt/SrX was found. On the other hand, Pt/FIX catalyst shows higher activity and selectivity than that of Pt/SrX.it was concluded that, only an average of 90 wt% of the carbon atoms fled into the reactor (light naphtha) is detected in the product strewn due to formation of coke deposits which leads to catalyst deactivation. The results clearly showed that hydrogen is necessary for the hydrogenation of olefins in order to prevent oligomerization reaction that leads to coke formation and catalyst deactivation.

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