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Effect of Adding Scoria as Cement Replacement on Durability-Related Properties
Aref Mohamad al-Swaidani,Samira Dib Aliyan 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.2
A lot of reinforced concrete (RC) structures in Syria went out of service after a few years of construction. This was mainly due to reinforcement corrosion or chemical attack on concrete. The use of blended cements is growing rapidly in the construction industry due to economical, ecological and technical benefits. Syria is relatively rich in scoria. In the study, mortar/concrete specimens were produced with seven types of cement: one plain Portland cement (control) and six blended cements with replacement levels ranging from 10 to 35 %. Rapid chloride penetration test was carried in accordance with ASTM C 1202 after two curing times of 28 and 90 days. The effect on the resistance of concrete against damage caused by corrosion of the embedded steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential. The variation of current with time and time to failure of RC specimens were determined at 28 and 90 days curing. In addition, effects of aggressive acidic environments on mortars were investigated through 100 days of exposure to 5 % H₂SO₄, 10 % HCl, 5 % HNO₃ and 10 % CH₃COOH solutions. Evaluation of sulfate resistance of mortars was also performed by immersing in 5 % Na₂SO₄ solution for 52 weeks. Test results reveal that the resistance to chloride penetration of concrete improves substantially with the increase of replacement level, and the concretes containing scoria based-blended cements, especially CEM II/B-P, exhibited corrosion initiation periods several times longer than the control mix. Further, an increase in scoria addition improves the acid resistance of mortar, especially in the early days of exposure, whereas after a long period of continuous exposure all specimens show the same behavior against the acid attack. According to results of sulfate resistance, CEM II/B-P can be used instead of SRPC in sulfate-bearing environments.
Basem Aref Frasin,Ala Amourah,Tariq Al-Hawary 경북대학교 자연과학대학 수학과 2022 Kyungpook mathematical journal Vol.62 No.2
In the present paper, a subclass of analytic and bi-univalent functions is defined using a symmetric q−derivative operator by means of Gegenbauer polynomials. Coefficients bounds for functions belonging to this subclass are obtained. Furthermore, the Fekete-Szego problem for this subclass is solved. A number of known or new results are shown to follow upon specializing the parameters involved in our main results.
Effect of molar ratios on strength, microstructure & embodied energy of metakaolin geopolymer
Abadel, Aref A.,Albidah, Abdulrahman S.,Altheeb, Ali H.,Alrshoudi, Fahed A.,Abbas, Husain,Al-Salloum, Yousef A. Techno-Press 2021 Advances in concrete construction Vol.11 No.2
In this study, twenty-five geopolymer (GP) mixes were prepared by varying the alkaline solids to Metakaolin (MK) and sodium silicate to NaOH ratios from 0.1 to 0.5 and 0.2 to 1.0, respectively, thus giving a wide range of molar ratios of silica to alumina, sodium oxide to alumina and water to sodium oxide. The compressive strength of these GP mixes was determined for four curing schemes involving oven curing at 100℃ for 24 h and three ambient curing with the curing ages of 3, 14, and 28 days. The test results revealed that for the manufacture of GP binder for structural applications of strength up to 90 MPa, the molar ratio of silica to alumina should be greater than 2.3, sodium oxide to alumina should be between 0.6 to 1.2, and water to sodium oxide should not exceed 12. The compressive strength of ambient cured GP mortar gets stabilized at 28 days of ambient curing. Experimental findings were also corroborated by GP microstructure analysis. The embodied energy of MK-based GP mortars, especially of high strength, is significantly less than the cement mortar of equivalent strength.
Agob, Jamila Nuwayji,Aref, Neven Saad,Al-Wakeel, Essam El Saeid The Korean Academy of Conservative Dentistry 2018 Restorative Dentistry & Endodontics Vol.43 No.4
Objectives: This study was conducted to evaluate fluoride release and the micro-shear bond strength of resin-modified glass ionomer cement (RMGIC) in casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-remineralized caries-affected dentin (CAD). Materials and Methods: Exposed dentin surfaces of 30 human third molar teeth were divided into 2 equal groups for evaluating fluoride release and the micro-shear bond strength of RMGIC to CAD. Each group was subdivided into 3 equal subgroups: 1) control (sound dentin); 2) artificially demineralized dentin (CAD); 3) CPP-ACP remineralized dentin (remineralized CAD). To measure fluoride release, 15 disc-shaped specimens of RMGIC (4 mm in diameter and 2 mm in thickness) were bonded on one flat surface of the dentin discs of each group. Fluoride release was tested using ion chromatography at different intervals; 24 hours, 3, 5, 7 days. RMGIC micro-cylinders were built on the flat dentin surface of the 15 discs, which were prepared according to the assigned group. Micro-shear bond strength was measured after 24 hours water storage. Data were analyzed using 1- and 2-way analysis of variance and the post hoc least significant difference test (${\alpha}=0.05$). Results: Fluoride detected in solutions (at all intervals) and the micro-shear bond strength of RMGIC bonded to CPP-ACP-remineralized dentin were significantly higher than those bonded to artificial CAD (p < 0.05). Conclusions: Demineralized CAD consumes more fluoride released from RMGIC into the solution for remineralization than CPP-ACP mineralized dentin does. CPP-ACP increases the micro-shear bond strength of RMGIC to CAD.
Evaluation of Atherosclerotic Plaque in Non-invasive Coronary Imaging
Aeshita Dwivedi,Subhi J. Al’Aref,Fay Y. Lin,James K. Min 대한심장학회 2018 Korean Circulation Journal Vol.48 No.2
Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Over the last decade coronary computed tomography angiography (CCTA) has gained wide acceptance as a reliable, cost-effective and non-invasive modality for diagnosis and prognostication of CAD. Use of CCTA is now expanding to characterization of plaque morphology and identification of vulnerable plaque. Additionally, CCTA is developing as a non-invasive modality to monitor plaque progression, which holds future potential in individualizing treatment. In this review, we discuss the role of CCTA in diagnosis and management of CAD. Additionally, we discuss the recent advancements and the potential clinical applications of CCTA in management of CAD
Arafat Khalphallah,Nasr-Eldin M. Aref,Ashraf M. Abu-Seida,Enas Elmeligy,Sara A. Bayoumi,Al-lethie A. Al-lethie,Doaa Salman 대한수의학회 2018 Journal of Veterinary Science Vol.19 No.4
This study describes ultrasonographic observations of five hepatobiliary diseases in buffalo (Bubalus bubalis). Fifty buffalo, including 20 clinically normal and 30 hepatobiliary diseased buffalo were enrolled in the study. Complete clinical, radiographic and ultrasonographic examinations and laboratory analyses were conducted. Focal parenchymal lesions including liver abscess (n = 12) and hepatic cyst (n = 6), diffuse parenchymal lesion (hepatobiliary cirrhosis, n = 5) and obstruction of hepatobiliary passages including cholestasis (n = 4), and hepatocholelithiasis (n = 3) were successfully imaged by ultrasonography. Hepatic abscess imaged as a hypoechoic to echogenic circumscribed mass of various diameters with a distinct echogenic capsule. Hepatic cyst imaged as a pear-shaped sac with a bright echogenic margin, anechoic content, and distal acoustic enhancement. In hepatobiliary fibrosis, the liver showed linear bands of increasing echogenicity with less distinct imaging of the portal vasculature. Cholestasis was imaged as dilatation of the gallbladder (GB) with wall thickening and homogeneous or heterogeneous contents. Hepatocholelithiasis imaged as an echoic structure within the hepatic parenchyma, or within and around the GB and bile duct, with more echogenicity of the hepatic parenchyma than normal. Ultrasonography can be an efficient rapid, noninvasive tool for screening of common hepatobiliary diseases in buffalo under field conditions.
Jamila Nuwayji Agob,Neven Saad Aref,Essam El Saeid Al-Wakeel 대한치과보존학회 2018 Restorative Dentistry & Endodontics Vol.43 No.4
Objectives: This study was conducted to evaluate fluoride release and the micro-shear bond strength of resin-modified glass ionomer cement (RMGIC) in casein phosphopeptide�amorphous calcium phosphate (CPP-ACP)-remineralized caries-affected dentin (CAD). Materials and Methods: Exposed dentin surfaces of 30 human third molar teeth were divided into 2 equal groups for evaluating fluoride release and the micro-shear bond strength of RMGIC to CAD. Each group was subdivided into 3 equal subgroups: 1) control (sound dentin); 2) artificially demineralized dentin (CAD); 3) CPP-ACP remineralized dentin (remineralized CAD). To measure fluoride release, 15 disc-shaped specimens of RMGIC (4 mm in diameter and 2 mm in thickness) were bonded on one flat surface of the dentin discs of each group. Fluoride release was tested using ion chromatography at different intervals; 24 hours, 3, 5, 7 days. RMGIC micro-cylinders were built on the flat dentin surface of the 15 discs, which were prepared according to the assigned group. Micro-shear bond strength was measured after 24 hours water storage. Data were analyzed using 1- and 2-way analysis of variance and the post hoc least significant difference test (α = 0.05). Results: Fluoride detected in solutions (at all intervals) and the micro-shear bond strength of RMGIC bonded to CPP-ACP-remineralized dentin were significantly higher than those bonded to artificial CAD (p < 0.05). Conclusions: Demineralized CAD consumes more fluoride released from RMGIC into the solution for remineralization than CPP-ACP mineralized dentin does. CPP-ACP increases the micro-shear bond strength of RMGIC to CAD.
Reliability Assessment of HFRC Slabs Against Projectile Impact
Nadeem A. Siddiqui,Yousef A. Al?Salloum,Tarek H. Almusallam,Aref A. Abadel,Husain Abbas 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.6
In the present study, a probabilistic procedure is presented for estimating the reliability of hybrid fiber reinforced concrete (HFRC) slabs against the impact of hemispherical nose projectiles considering uncertainties involved in the material, geometric and impact parameters. The influence of hybrid fibers in improving the safety level of reinforced concrete slabs against impact loads has also been studied on a parametric basis. The failure of the HFRC slabs was assumed to occur when the impact velocity of the projectile exceeds the ballistic limit of the slab i.e. perforates the slab. To illustrate the procedure, a probabilistic analysis was carried out on the impact test results of HFRC slabs containing different proportions of hooked-end steel, polypropylene and Kevlar fibers, recently published by the authors. Reliability assessment was performed for a range of applied nominal impact loads by varying the impact velocity of the given projectile. Reliability analysis yields the safety level of all the HFRC slabs against the impact of the above projectile. Effect of fibers, especially steel fibers, and slab thickness on the reliability of HFRC slabs are also investigated on a parametric basis.