Background: Radiopacity is one of the prerequisites for dental materials, especially for composite restorations. It's essential for easy detection of secondary dental caries as well as observation of the radiographic interface between the materials and tooth structure. The aim of this study to assess the difference in radiopacity of different resin composites using a digital x-ray system. Materials and methods: Ten specimens (6mm diameter and 1mm thickness) of three types of composite resins (Evetric, Estelite Sigma Quick,and G-aenial) were fabricated using Teflon mold. The radiopacity was assessed using dental radiography equipment in combination with a phosphor plate digital system and a grey scale value aluminum step wedge with thickness varying from 1mm to 10mm in steps of 1mm each. The tested materials were radiographed, we used Image J software, on a computer screen to evaluate the degree of radiopacity for each individual material and compare with the aluminum step wedge. Radiopacity was expressed in mm of equivalent aluminum step wedge. Analysis of varience (ANOVA) and Least Significant Difference (LSD) were used to investigate the significance of differences among the tested groups. Results: Statistical analysis showed highly significant difference among the tested groups (p≤0.01). Amongst, G-aenial composite shows the most radiopaque and it is above or equivalent to that of enamel, while Estelite Sigma Quick composite has the lowest radiopacity value and is equivalent to that of dentin. Conclusion: In line with previous studies, and within the limitation of our study, considerable variations in radiopacity values were found among materials depending on the radiopaque elements incorporated into the matrix. All composite materials tested complied with the ISO 4049 standard.
In this paper, an analytical solution describing the deflection of a cracked beam repaired with piezoelectric patch is introduced. The solution is derived using perturbation method. A novel analytical model to calculate the proper dimensions of piezoelectric patches used to repair cracked beams is also introduced. This model shows that the thickness of the piezoelectric patch depends mainly on the thickness of the cracked beam, the electro-mechanical properties of the patch material, the applied load and the crack location. Furthermore, the model shows that the length of the piezoelectric patches depends on the thickness of the patch as well as it depends on the length of the cracked beam and the crack depth. The additio
... Show MoreA field Experiment was carried out in Baghdad for the purpose of compare five horticulture machines during used two types of fuel deffirance in octane number, normal and super fuel which produced in Iraqi and measuring the vibrations transmitted of the three axes are longitudinal X , lateral Y and vertical Z from handlebar in (Mowers) to the operator which walks behind the mower, and the determine of the productivity practical of cutting, productivity passing and fuel consumption. Experiment Factorial used with two factors, The first factor was Five Mowers vary in width , types, weight and company manufacturer, The Second factor was the types of fuel used internal combination engine horticulture mowers were Normal fuel with Octane Number 82
... Show MoreThe present study was conducted on spring-fed(Abdullah Abu-Nadjem Oasis)west of AlDewanyah province,Iraq. ,during Winter 2007. The results indicate that water quality was neutral tend to be slightly alkaline pH was 7.7 and 7.4 for station(1)and station (2) respectively. Total hardness value of water about 1520 and 1488 mg/l.for two stations respectively ,This high values of hardness may be due to Calcium ions 397.5 and 395.5mg/l.for two stations. According to Salinity values (1.58 - 2.22) ‰(ppt) ,water of oasis may be classified as brackish water, the oasis water was well aerated dissolved oxygen was 5.3 and 7.4 mg/l. On the other hand about (58) algal taxa were recorded
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Background: Pneumonia is a common form of lower respiratory tract infection (LRTI) in children under five years of age and it is the leading cause of morbidity and mortality in this age group. Early management is important in decreasing its complications and mortality.
Methods: A cross sectional study of 100 patients, their ages ranged from 2 months to 5 years. They were admitted to Children Welfare Teaching Hospital Medical City–Baghdad in a period from 7th of November 2010 to 5th of May 2011, suffering from Lower Respiratory Tract Infections (fever, cough and tachypnea) and classified into two groups according to chest radiograph (CXR) findings, those with a patch (pneumonia) and others with normal or hyper inflated CX
The goal of this paper is to study dynamic behavior of a sporadic model (prey-predator). All fixed points of the model are found. We set the conditions that required to investigate the local stability of all fixed points. The model is extended to an optimal control model. The Pontryagin's maximum principle is used to achieve the optimal solutions. Finally, numerical simulations have been applied to confirm the theoretical results.
The aim of the current paper is to resolve the non-uniqueness in gravity interpretation through searching for singular points in the gravity field that are coincide with causative body vertices. The Absolute Second Horizontal Gradient (ASHG) method is used to locate the horizontal reference location of the body, while its amplitude could be used to define body corner depth. Intelligent use of the ASHG method could help in differentiating between basin and intrusion structures from their gravity effect and could facilitate the interpretation in forward modeling and constrain inversion modeling to maximum limit. The method is tested by using many synthetic examples with different types of shapes. A real data is used to examine the method a
... Show MoreDue to the potential cost saving and minimal temperature stratification, the energy storage based on phase-change materials (PCMs) can be a reliable approach for decoupling energy demand from immediate supply availability. However, due to their high heat resistance, these materials necessitate the introduction of enhancing additives, such as expanded surfaces and fins, to enable their deployment in more widespread thermal and energy storage applications. This study reports on how circular fins with staggered distribution and variable orientations can be employed for addressing the low thermal response rates in a PCM (Paraffin RT-35) triple-tube heat exchanger consisting of two heat-transfer fluids flow in opposites directions throug
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