Background: The objective of this in vitro study was to evaluate the vertical marginal fit of crowns fabricated with ZrO2 CAD/CAM, before and after porcelain firing cycles and after glaze cycles. Materials and Methods: An acrylic resin model of a left maxillary first molar was prepared and duplicated to have Nickel-Chromium master die. Ten die stone dies were sent to the CAD/CAM (Amann Girrbach) for crowns fabrication. Marginal gaps along vertical planes were measured at four indentations at the (mid mesial, mid distal, mid buccal, mid palatal) before (Time 0) and after porcelain firing cycles (Time 1) and after glaze cycles (Time 2) using a light microscope at a magnification of ×100. One way ANOVA LSD tests were performed to determine whether the mean and standard deviation of sub group Time 2. Results: The mean values of the ZrO2 CAD/CAM Time 0 were (6.77?m), Time 1(8.75?m) and Time 2(10.62 ?m). One way ANOVA test revealed highly statistical significance(P<0.01). LSD test results showed that there is highly significant difference between time (0) and time (2), while there is no any significant difference between time (0) and time (1), and between time (1) and time (2). Conclusions: Within the limitations of this study, it was concluded that the ZrO2 CAD/CAM demonstrated acceptable marginal fit; The porcelain firing and the glaze firing cycles affected the marginal gap
Nano TiO2 thin films on glass substrates were prepared at a constant temperature of (373 K) and base vacuum (10-3 mbar), by pulsed laser deposition (PLD) using Nd:YAG laser at 1064 nm wavelength. The effects of different laser energies between (700-1000)mJ on the properties of TiO2 films was investigated. TiO2 thin films were characterized by X-ray diffraction (XRD) measurements have shown that the polycrystalline TiO2 prepared at laser energy 1000 mJ. Preparation also includes optical transmittance and absorption measurements as well as measuring the uniformity of the surface of these films. Optimum parameters have been identified for the growth of high-quality TiO2 films
... Show Moreملخص البحث: تناول البحث الحالي:(أنظمة التكوين الجمالي للكتابات والنصوص في النحت العربي المعاصر)، عددا من الأفكار الأساسية التي تمثل المادة النظرية لتفسير ظاهرة الكتابة في الفن بشكل عام وفي فن النحت بشكل خاص، ولكشف أنظمة التكوين الجمالي وأنواعها المتعددة من خلال فحص بعض النصوص البصرية للفنانين العرب المعاصرين، فقد جاء هذا البحث في أربعة فصول. خصص الفصل الأول: الإطار المنهجي للبحث لبيان مشكلة البحث، وأهم
... Show MoreIn this work, the effect of preparing a composite of copper oxide nanoparticles with carbon on some of its optical properties was studied. The composite preparing process was carried out by exploding graphite electrodes in an aqueous suspension of copper oxide. The properties of the plasma which is formed during the explosion were studied using emission spectroscopy in order to determine the most important elements that are present in the media. The electron’s density and their energy, which is the main factor in the composite process, were determined. The particle properties were studied before and after the exploding process. The XRD showed an additional peak in the copper oxides pattern corresponding to the hexagonal graphite struct
... Show MoreTheoretical and experimental investigations of the transient heat transfer parameters of constant heat flux source subjected to water flowing in the downward direction in closed channel are conducted. The power increase transient is ensured by step change increase in the heat source power. The theoretical investigation involved a mathematical modeling for axially symmetric, simultaneously developing laminar water flow in a vertical annulus. The mathematical model is based on one dimensional downward flow. The boundary conditions of the studied case are based on adiabatic outer wall, while the inner wall is subjected to a constant heat flux. The heat & mass balance equation derived for specified element of bulk water within the annulu
... Show MoreThis study uses an environmentally friendly and low-cost synthesis method to manufacture zinc oxide nanoparticles (ZnO NPs) by using zinc sulfate. Eucalyptus leaf extract is an effective chelating and capping agent for synthesizing ZnO NPs. The structure, morphology, thermal behavior, chemical composition, and optical properties of ZnO nanoparticles were studied utilizing FT-IR, FE-SEM, EDAX, AFM, and Zeta potential analysis. The FE-SEM pictures confirmed that the ZnO NPs with a size range of (22-37) nm were crystalline and spherical. Two methods were used to prepare ZnO NPs. The first method involved calcining the resulting ZnO NPs, while the second method did not. The prepared ZnO NPs were used as adsorbents for removing acid black 210
... Show MoreGraphene oxide (GO) was prepared from graphite (GT) with Hammer method, the GO was reduced with hydrazine hydrate to produce a reduced graphene oxide (RGO). The RGO was reacted with thiocarbohydrazide (TCH) to functionalize the RGO with 4-amino-3-symbol-1h-1, 2, 4-triazol-5 (4H) –thion group and to obtain (RGOT). All the prepared nanomaterial and the product of the functionalization RGOT were characterized with Fourier transformer infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis. RGOT mixed with ultrasonic device at different pH values of phosphate buffer solution (PBS), the mixture used to modifying a screen printed carbon electrodes SPCE and with cyclic voltammetry the sensitivity of selectivity of the new modifying elect
... Show MoreThe alfalfa plant, after harvesting, was washed, dried, and grinded to get fine powder used in water treatment. We used the alfalfa plant with ethanol to make the alcoholic extract characterized by using (GCMass, FTIR, and UV) spectroscopy to determine active compounds. Alcoholic extract was used to prepare zinc nanoparticles. We characterized Zinc nanoparticles using (FTIR, UV, SEM, EDX Zeta potential, XRD, AFM). Zinc nanoparticle with Alfalfa extract and alfalfa powder were used in the treatment of water polluted with inorganic elements such as Cr, Mn, Fe, Cu, Cd, Ag by (Batch processing). The batch process with using alfalfa powder gets treated with Pb (51.45%), which is the highest percentage of treatment. Mn (13.18%), which is the lowe
... Show MoreThe alfalfa plant, after harvesting, was washed, dried, and grinded to get fine powder used in water treatment. We used the alfalfa plant with ethanol to make the alcoholic extract characterized by using (GC-Mass, FTIR, and UV) spectroscopy to determine active compounds. Alcoholic extract was used to prepare zinc nanoparticles. We characterized Zinc nanoparticles using (FTIR, UV, SEM, EDX Zeta potential, XRD, AFM). Zinc nanoparticle with Alfalfa extract and alfalfa powder were used in the treatment of water polluted with inorganic elements such as Cr, Mn, Fe, Cu, Cd, Ag by (Batch processing). The batch process with using alfalfa powder gets treated with Pb (51.45%), which is the highest percentage of treatment. Mn (13.18%), which is the
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