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PubMed | University of Thamar and Wuhan University of Technology
Type: | Journal: SpringerPlus | Year: 2015

This study aimed to analyse and compare the stability of two dental posts cemented with four different luting agents by examining their shear stress transfer through the FEM. Eight three-dimensional finite element models of a maxillary central incisor restored with glass fiber and Ni-Cr alloy cast dental posts. Each dental post was luted with zinc phosphate, Panavia resin, super bond C&B resin and glass ionomer materials. Finite element models were constructed and oblique loading of 100 N was applied. The distribution of shear stress was investigated at posts and cement/dentine interfaces using ABAQUS/CAE software. The peak shear stress for glass fiber post models minimized approximately three to four times of those for Ni-Cr alloy cast post models. There was negligible difference in peak of shear stress when various cements were compared, irrespective of post materials. The shear stress had same trend for all cement materials. This study found that the glass fiber dental post reduced the shear stress concentration at interfacial of post and cement/dentine compared to Ni-Cr alloy cast dental post.


Yu K.,University of Sichuan | Yue X.-G.,Wuhan University | Madfa A.A.,University of Thamar | Du Y.-H.,University of Sichuan
Journal of Computational and Theoretical Nanoscience | Year: 2016

The PBL Teaching Mode is a teaching method widely used in today's medical colleges. Article outlines the development of PBL, PBL teaching model summarized in our medical colleges' embodiment and PBL based network teaching platform, a medical student of University for the study, using GLM analysis comparative study by PBL and traditional teaching methods and advantages of different teaching methods. To promote the transformation of higher medical educational philosophy, curriculum reconstruction system, innovative teaching methods provide a new way of thinking. Copyright © 2016 American Scientific Publishers All rights reserved.


Al-Areeq N.M.,University of Thamar | Maky A.F.,Egyptian Petroleum Research Institute
Marine and Petroleum Geology | Year: 2015

The objective of this study is to provide information on source organic matter input, depositional conditions and the correlation between crude oils recovered from Sunah oilfield and Upper Jurassic Madbi Formation. A suite of twenty-six crude oils from the Lower Cretaceous reservoirs (Qishn clastic) of the Masila Region (Eastern Yemen) were analysed and geochemically compared with extracts from source rock of the Upper Jurassic (Madbi Formation). The investigated biomarkers indicated that the Sunah oils were derived from mixed marine and terrigenous organic matter and deposited under suboxic conditions. This has been achieved from normal alkane and acyclic isoprenoids distributions, terpane and sterane biomarkers. These oils were also generated from source rock with a wide range of thermal maturity and ranging from early-mature to peak oil window. Based on molecular indicators of organic source input and depositional environment diagnostic biomarkers, one petroleum system operates in the Masila Region; this derived from Upper Jurassic Madbi organic-rich shales as source rock. Therefore, the hydrocarbon exploration processes should be focused on the known location of the Upper Jurassic Madbi strata for predicting the source kitchen. © 2015 Elsevier Ltd.


PubMed | University of Leipzig, University of Thamar and IPO Institute for Pathology
Type: Journal Article | Journal: Clinical oral investigations | Year: 2016

The study was conducted to investigate the role of qat and smoking habits on the prevalence of visible and cytological abnormalities in the oral mucosa among Yemenites.We recruited 30 non-smoking and 30 smoking Yemenites chewing qat unilaterally for at least 5 years. We inspected oral cavities for the presence of lesions and took brush biopsies from the buccal mucosa/gingiva of the chewing/non-chewing region.All visible oral lesions were flat and homogeneous, and cytological changes were detected frequently. Among both non-smokers and smokers, white lesions and cytological changes were detected in 77% of all cases. On the chewing area, the proportion with white lesions ranged--depending on anatomical area and smoking status--between 47 and 93% and was significantly more frequent than on the non-chewing side (range 3-47%). The proportion of regions with changes was similar in non-smokers and smokers. Kappa statistics for interobserver agreement between visual inspection and cytological specimens of brush biopsies was at best fair (0.25).The high prevalence of visible lesions and cytological abnormalities among qat chewers was independent of smoking status.The moderate level of agreement between visual inspection and exfoliative cytology demonstrates the still challenging clinical management of chronic qat chewers, though brush biopsies including adjuvant techniques like DNA cytometry may support the clinical decision-making process in future.


Munther A.,University Malaysia Perlis | Alalousi A.,University of Thamar | Nizam S.,University Malaysia Perlis | Othman R.R.,University Malaysia Perlis | Anbar M.,Universiti Sains Malaysia
2014 2nd International Conference on Electronic Design, ICED 2014 | Year: 2014

Network traffic classification gains continuous interesting while many applications emerge on the different kinds of networks with obfuscation techniques. Decision tree is a supervised machine learning method used widely to identify and classify network traffic. In this paper, we introduce a comparative study focusing on two common decision tree methods namely: C4.5 and Random forest. The study offers comparative results in two different factors are accuracy of classification and processing time. C4.5 achieved high percentage of classification accuracy reach to 99.67 for 24000 instances while Random Forest was faster than C4.5 in term of processing time. © 2014 IEEE.


Hakimi M.H.,Taiz University | Abdullah W.H.,University of Malaya | Areeq N.M.A.,University of Thamar
Fuel | Year: 2014

This study is the first attempt which provides information regarding the organic geochemical, biomarker and petrographic characteristics of the Upper Cretaceous coals found in the in the Jiza-Qamar Basin, eastern Yemen. The geochemical and petrographic results helped us to evaluate the type of organic matter, thermal maturity, and petroleum-generation potential, as well as depositional environments of the coals. Maceral analysis shows that the coals are dominated by vitrinite, with significant amounts of liptinite, and low amounts of inertinite macerals. Liptinite present in the samples are oil-prone liptinite macerals include petroleum-like materials (exsudatinite). The Upper Cretaceous coals are high volatile B-A bituminous in rank, possessing vitrinite reflectance in the range of 0.62-0.87%Ro. This rank determination is supported by high fixed carbon and relatively low volatile matter contents, with an arithmetic mean of 54.8 wt.% and 41.9 wt.%, respectively. Upper Cretaceous coals with moderate to high oil-prone liptinite content have good liquid petroleum-generation potential. These coals have relatively high hydrogen index values in the range of 286-449 mg HC/g TOC, consistent with Type II and mixed Type II-III kerogens. Gas chromatograms present in the coal samples are dominated by odd carbon numbered n-alkanes (n-C23 to n-C 35), indicating terrestrial organic matter input. The biomarker parameters obtained from mass spectrometer data on m/z 191 and m/z 217 indicate that these coals were deposited in a fluvial to deltaic environments and preserved under relatively oxic conditions. The Tmax, mean vitrinite reflectance and biomarker maturity data show that Upper Cretaceous coals fall into the early-mature to peak oil window. © 2013 Elsevier Ltd. All rights reserved.


Alalousi A.,Universiti Sains Malaysia | Osman A.,Universiti Sains Malaysia | Noori S.,Universiti Sains Malaysia | Hussain A.,Universiti Sains Malaysia | And 2 more authors.
European Journal of Scientific Research | Year: 2011

Video conferencing applications require high bandwidth to distribute video chunks. In general, video chunks distribution can be done through two approaches: A centralized network or an overlay network. However, the centralized network is expensive and not scalable. Therefore, many systems have resorted to the use of overlay network, which offers low cost and scalable systems by utilizing the resources of the node better. The current paper presents the two approaches for the video conferencing system, focusing on the systems that use the overlay network approach. It describes the challenges and solutions for distributing video chunks across different types of overlay networks centering on application layer multicast and peer-to-peer (P2P) network. The overlay network, particularly the hybrid system of peer- to-peer and application layer multicast, was found to be the optimal system in terms of scalability, bandwidth utilization, less delay, high quality, low cost, less congestion control, and better handling with heterogeneous network. © EuroJournals Publishing, Inc. 2011.


Madfa A.A.,University of Thamar | Kadir M.R.A.,University of Technology Malaysia | Kashani J.,University of Technology Malaysia | Saidin S.,University of Technology Malaysia | And 6 more authors.
Medical Engineering and Physics | Year: 2014

Different dental post designs and materials affect the stability of restoration of a tooth. This study aimed to analyse and compare the stability of two shapes of dental posts (parallel-sided and tapered) made of five different materials (titanium, zirconia, carbon fibre and glass fibre) by investigating their stress transfer through the finite element (FE) method. Ten three-dimensional (3D) FE models of a maxillary central incisor restored with two different designs and five different materials were constructed. An oblique loading of 100. N was applied to each 3D model. Analyses along the centre of the post, the crown-cement/core and the post-cement/dentine interfaces were computed, and the means were calculated. One-way ANOVAs followed by post hoc tests were used to evaluate the effectiveness of the post materials and designs (p= 0.05). For post designs, the tapered posts introduced significantly higher stress compared with the parallel-sided post (p < 0.05), especially along the centre of the post. Of the materials, the highest level of stress was found for stainless steel, followed by zirconia, titanium, glass fibre and carbon fibre posts (p < 0.05). The carbon and glass fibre posts reduced the stress distribution at the middle and apical part of the posts compared with the stainless steel, zirconia and titanium posts. The opposite results were observed at the crown-cement/core interface. © 2014 IPEM.


Al-Sanabani J.S.,University of Thamar | Madfa A.A.,University of Thamar | Al-Sanabani F.A.,University of Thamar
International Journal of Biomaterials | Year: 2013

Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields. © 2013 Jabr S. Al-Sanabani et al.


Bounihi A.,Mohammed V University | Hajjaj G.,Mohammed V University | Alnamer R.,Mohammed V University | Alnamer R.,University of Thamar | And 2 more authors.
Advances in Pharmacological Sciences | Year: 2013

Melissa officinalis L. (Lamiaceae) had been reported in traditional Moroccan medicine to exhibit calming, antispasmodic, and strengthening heart effects. Therefore, this study is aimed at determining the anti-inflammatory activities of M. officinalis L. leaves. The effect of the essential oil of the leaves of this plant was investigated for anti-inflammatory properties by using carrageenan and experimental trauma-induced hind paw edema in rats. The essential oil extracted from leaves by hydrodistillation was characterized by means of gas chromatography-mass spectrometry (GC-MS). M. officinalis contained Nerol (30.44%), Citral (27.03%), Isopulegol (22.02%), Caryophyllene (2.29%), Caryophyllene oxide (1.24%), and Citronella (1.06%). Anti-inflammatory properties of oral administration of essential oil at the doses of 200, 400 mg/kg p.o., respectively, showed significant reduction and inhibition of edema with 61.76% and 70.58%, respectively, (P < 0.001) induced by carrageenan at 6 h when compared with control and standard drug (Indomethacin). On experimental trauma, M. officinalis L. essential oil showed pronounced reduction and inhibition of edema induced by carrageenan at 6 h at 200 and 400 mg/kg with 91.66% and 94.44%, respectively (P < 0.001). We can conclude that the essential oil of M. officinalis L. possesses potential anti-inflammatory activities, supporting the traditional application of this plant in treating various diseases associated with inflammation and pain. © 2013 Amina Bounihi et al.

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