Background: Dimensional changes of acrylic denture bases after polymerization results in need for further adjustments or even ends with technical failure of the finished dentures. The purpose of this study was to estimate the linear dimensional changes for different palatal depths when using multiple investment materials and polymerization techniques. Materials and methods: Ninety upper complete denture bases were constructed for this study. They were divided into two main groups according to the polymerization methods: conventional water bath and experimental autoclave (short and long cycles). Each main group was further subdivided into three subgroups according to the palatal depth (shallow, medium and deep). Furthermore, for each palatal depth; complete denture bases were invested either with dental stone or laboratory silicone. For each upper complete denture, measurements of linear dimensional changes were done by fixation of metallic screws on the tissue surface of the denture base. The distances were measured by using travelling microscope with an accuracy of 0.001 %. The data were statistically analyzed using three way analysis of variance (ANOVA) for three variables, which were (palatal depth, investments and polymerization techniques), LSD test and student T test for comparisons between groups. Results: There were significant improvements in the dimensional accuracy of denture bases cured with autoclave compared with water bath. Also, silicone investments were a successful alternative to stone, study data shows that short autoclave processing with silicone reduces the magnitude of the linear dimensional changes. On the other hand, long autoclave processing and stone investments were better than silicone in reducing dimensional changes. Conclusion: The findings of this study indicates that the use of autoclave processing in acrylic curing is a promising alternative to the conventional water bath and leads to better dimensional stability for the finished dentures in all oral configurations and palatal depths. Also, Silicone is more preferable than stone, although it's not as strong investing materials when compared with stone.
In the present work, Uranium (238U), Thorium (232Th) and Potassium (40K) specific activity concentration in (Bq/kg) was measured in five different types for wheat flours that are available in the Iraqi markets. The gamma spectrometry method with an NaI (Tl) detector has been used for radiometric measurements. Calculations of radium equivalent activity, annual effective dose equivalent, external hazard index (Hex), internal hazard index (Hin), representing gamma index and gamma dose rate in all flour samples were 17.98132 Bq/kg, 0.0100334, 0.04502, 0.04857, 0.06872, 0.125883 and 8.181244 respectively. It is found that the average of specific activity concentration of wheat flour sam
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Copper and Zinc powders with different particle sizes were subjected to sieving of range (20-100?m) and He-Ne laser system to determine the particle size . 1wt% from each powders was blended carefully with 99wt% from Iraqi oil . Microscopic examination were carried for all samples to reveal the particle size distribution . XRF intensity measurements were conducted for all suspended samples , and the relation between XRF intensity and the particle size was found .
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Angiotensin receptor blockers are well known for their therapeutic efficacy and fimasartan has been used safely and efficiently since 2010 in the treatment of hypertension. The study aimed to examine the anti-inflammatory effect of fimasartan in egg albumin-induced inflammation in rats. Rats were treated with diclofenac (25 mg/kg, intraperitoneally) or fimasartan at two different doses (3 or 10 mg/kg, intraperitoneally). The increase in the thickness of the paw was considered to be edema, which was measured using a vernier caliper. Serum was collected to analyze the systemic production of the inflammatory mediators TNF-α, and IL-6. The results showed that fimasartan in both doses significantly reduced edema in inflamed rat paws and produce
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Introduction: This study aimed to investigate sex differences in age-related changes to the dentoskeletal and soft tissue profile between 12-62 years of age using a superimposition-based cephalometric method. Methods: A total of 60 subjects (27 males and 33 females) were followed longitudinally. Lateral cephalograms were obtained at ages 12 (T1), 15 (T2), 30 (T3), and 62 (T4). Of note, 46 angular and linear cephalometric variables were measured using a cranial base-registered superimposition method that corrected for age-related displacement of the Nasion and Sella landmarks. Sex differences in changes between time points were analyzed using independent-samples t tests. Results: During adolescence (12-15 years of age), males exhibited great
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ABSTRUCT
In This Paper, some semi- parametric spatial models were estimated, these models are, the semi – parametric spatial error model (SPSEM), which suffer from the problem of spatial errors dependence, and the semi – parametric spatial auto regressive model (SPSAR). Where the method of maximum likelihood was used in estimating the parameter of spatial error ( λ ) in the model (SPSEM), estimated the parameter of spatial dependence ( ρ ) in the model ( SPSAR ), and using the non-parametric method in estimating the smoothing function m(x) for these two models, these non-parametric methods are; the local linear estimator (LLE) which require finding the smoo
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Determination of the concentrations of some inorganic elements (Fe, Co, Cu, Cr, Ni, Pb, Cd) by Flame Atomic Absorption Spectroscopy, Electrothermal Atomic Absorption Spectroscopy, and Inductively Coupled Plasma. and two dangerous organic pollutants (PAH and phenols) by GC and UV in the wastewater of Z.LTF Zafaraniya Leather tanning factory, W.BF Al-Waziriya Battery factory, Ba.WLS Al-Bayaa Wastewater Lifting Station, and some points of Tigris River in Baghdad city taking into consideration the sampling time Varying (two months) and setting the temperature during the drawing of the model. The results of the analysis revealed that the wastewater was contaminated with phenols, PAHs, and metals (Pb, Cd, Cr, Cu) at high rates that exceeded the p
... Show MoreIn this paper, we introduce an exponential of an operator defined on a Hilbert space H, and we study its properties and find some of properties of T inherited to exponential operator, so we study the spectrum of exponential operator e^T according to the operator T.
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A numerical method (F.E.)was derived for incompressible viscoelastic materials, the aging and
environmental phenomena especially the temperature effect was considered in this method. A
treatment of incompressibility was made for all permissible values of poisons ratio. A
mechanical model represents the incompressible viscoelastic materials and so the properties can
be derived using the Laplace transformations technique .A comparison was made with the other
methods interested with viscoelastic materials by applying the method on a cylinder of viscoelastic material surrounding by a steel casing and subjected to a constant internal pressure, as well as a comparison with another viscoelastic method and for Asphalt Concrete pro
Many researchers have tackled the shear behavior of Reinforced Concrete (RC) beams by using different kinds of strengthening in the shear regions and steel fibers. In the current paper, the effect of multiple parameters, such as using one percentage of Steel Fibers (SF) with and without stirrups, without stirrups and steel fibers, on the shear behavior of RC beams, has been studied and compared by using Finite Element analysis (FE). Three-dimensional (3D) models of (RC) beams are developed and analyzed using ABAQUS commercial software. The models were validated by comparing their results with the experimental test. The total number of beams that were modeled for validation purposes was four. Extensive pa
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