Background: the aim of this study was to evaluate the effect of different surface acids treatments (37%phospjoric acid, 5%hydrofluoric acid, 1.23 acidulated phosphate fluoride) of feldspathic ceramic VITA 3D MASTER , and the effect of thermocycling on shear bond strength using a ceramic repair kit (ivoclar/vivadent). Material and Methods: sixty Nickel-Chromium metal base plates were prepared(9mm diameter,3mm depth) using lost wax technique, 2mm thick layer of ceramic(VITA 3D MASTER) fused to metal plates, all specimens were embedded in acrylic resin blocks except their examined surfaces and divided into 3 main groups 20 specimens each, Grp A: treatment with 37%phosphoric acid for 2 mins, Grp B: etching with 5% hydrofluoric acid for 2mins, Grp C: etching with 1.23% acidulated phosphate fluoride for 10 mins; monobond-plus, heliobond, resin composite(Tetric EvoCeram) were applied to each specimen according to manufacturer's instruction using transparent split mold(5mm diameter, 4 mm height); specimens were stored in 37OC distilled water for 12 weeks, 10 specimens of each group were subjected to thermocycling between 5 oC and 55 o C for 800 cycles with 30s dwell time; shear bond strength was determined by a universal testing machine (instron 1122) at a cross head speed 0.5mm/min; One way ANOVA test, LSD test and student-t test were used to analyze shear bond strength. Results: Mean shear bond strength values for the tested groups were: A1= 11.65±0.68 Mpa, A2=10.88±0.58 Mpa, B1=17.93±0.41 Mpa, B2=17.42±0.35 Mpa, C1=15.17±0.61 Mpa, C2=14.51±0.48 Mpa ; one way ANOVA test showed highly significant difference among groups; LSD test revealed that the use of 5% HF for ceramic surface treatment(GB) was highly significant than the treatment with 37%PA(GA) or 1.23%APF(GC) respectively and the use of 1.23%APF(GC) was highly significant than the use of 37%PA(GA); Student t- test showed a significant difference between subgroups of the same group with and without thermocycling. Conclusion: ceramic surface treated with 5% HF acid for 2 mins recorded the highest shear bond strength, followed by surface treatment with 1.23% APF for 10 mins, most specimens treated with 5%HF showed cohesive failure with in ceramic while specimens treated with 1.23%AFP showed more (adhesive/cohesive) failure than adhesive or cohesive alone, and specimens treated with 37% PA showed nearly 50:50 adhesive and combination failure, thermocycling reduced the bond strength of each group significantly
To observe the effect of media of the internal pressure on the equivalent stress distribution in the tube, an experimental study is done by constructing a testing rig to apply the hydraulic pressure and three dies are manufactured with different bulging configurations (square, cosine, and conical). In the other part, ANSYS APDL is generated to analyze the bulging process with hydraulic and rubber (natural and industrial) media. It was found that when the media is a rubber, the stress is decreased about 9.068% in case of cosine die and 5.4439% in case of conical die and 2.8544% in case of square die. So, it can be concluded that the internal pressure in the rubber media is much better than in hydraulic media. Also, the force needed for fo
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to evaluate the effect of various Nd:YAG frequency doubled laser parameters on the acid
dissolution and the progression of in vitro caries like lesions in human enamel.
Materials and Methods: Human extracted caries free upper first premolar teeth were collected for
this study. The irradiated teeth were divided into two groups. The first group was irradiated with
continuous Nd:YAG laser radiation, and the second group was irradiated with chopped Nd:YAG laser
radiation. For the first group, power and exposure time were changed while for the second group
power and number of pulses were changed. The spot diameter was kept constant for all the samples.
Results: using 1.5 W and 3 seconds (exposure time), best results among
Sewage pumping stations are considered an important part of any sewerage system. Pumps failure in these stations means that the pumps are unable to work at the design requirement (flow capacity and head) and that may cause sewer overflow and flooding leading to sewer deterioration. In this paper, two main sewage pumping stations in Baghdad city were selected as case studies, Al- Habibia and Al-Ghazali located on Zublin trunk sewer 3000 mm and Baghdad trunk sewer 1200-2100 respectively. This study focused mainly on the operation of main sewage pumping stations and their effect, both directly and indirectly, on changing hydraulic properties, which leads to an increase in the deterioration of sewage pipes. The hydraulic analysis was co
... Show MoreBackground: Moral distress, as one of the most important issues in the nursing profession, can negatively affect the healthcare system Objectives: To examine the effect of moral distress on decision making. Methodology: A descriptive cross-sectional study a non-probability sampling method was used and a total sample collected was (126) ICU nurses Result: Moral distress among ICUs nurses were moderate and decision making was good Conclusion: Although nurses in ICUs perceive good decision making but suffered from moderate MD which affected their decision making. MD is still an important issue that nurses may face in ICUs Conclusion: Although nurses in ICUs perceive good decision making but suffered from moderate MD which affected the
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Asthma is a chronic respiratory disorder in which immunological and structural cells play a role. The limits of conventional medicines necessitate the development of innovative therapeutic techniques for asthma. In the present study, we investigated the possible protective effect of cinnamic acid (CA) on ovalbumin-induced asthma in a mouse model. Sixty albino male mice BALB/c type weighing (20-30) grams were chosen at random and divided into five groups each one contains 12 animal: Group I: PBS/liquid paraffin control. Group II: asthma model group. Group III: cinnamic acid control group; mice received cinnamic acid (50 mg/kg) in liquid paraffin orally by gavage. Group IV: asthma model / group of (25 mg / kg) cinnamic acid; mice received
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(1)
The research aims to provide a method to measure the fair value of the most environmentally friendly of Iraq and through the application of method of measuring the fair value of the company garments contribute to mixed as the company is of the economic units of the industrial sector and included in the Iraqi market for securities as a profit and distributes profits to shareholders since the method of measurement of the fair value based on the divided profits as toxic in a deduction of Cash Dividends cash for measuring fair value, and will also be in this research to clarify the disclosure of accounting for fair value and choose the method of disclosure most appropriate to the beneficiaries of accounting disclosure, as will be cho
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An investigation was conducted for dewaxing of lubricating oil fraction by urea to reduce the pour point.In this study mixture of 45 % methyl ethyl ketone (MEK) and 55 % toluene was used as a solvent. The studied variables are mixing time (10-70 min), solvent to oil volume ratio (0.5:1- 2:1), urea to wax weight ratio (2- 6) and constant mixing speed 1500 rpm. By analysis of the experimental results, the best operating conditions achieved are mixing time 40 min, solvent/oil 2:1 volume ratio, and urea/wax 4:1 weight ratio. At these conditions the pour point of the lubricating oil decreases from 24 ° C to -13 °C.
In this study, an analysis of re-using the JPEG lossy algorithm on the quality of satellite imagery is presented. The standard JPEG compression algorithm is adopted and applied using Irfan view program, the rang of JPEG quality that used is 50-100.Depending on the calculated satellite image quality variation, the maximum number of the re-use of the JPEG lossy algorithm adopted in this study is 50 times. The image quality degradation to the JPEG quality factor and the number of re-use of the JPEG algorithm to store the satellite image is analyzed.
(4)
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In this study, the response and behavior of machine foundations resting on dry and saturated sand was investigated experimentally. A physical model was manufactured to simulate steady state harmonic load at different operating frequencies. The effect of relative density, depth of embedment, foundation area as well as the imposed harmonic load was investigated. It was found that the amplitude of displacement of the foundation increases with increasing the amplitude of dynamic force and operating frequency meanwhile it decreases with increasing the relative density of sand, degree of saturation, depth of embedment and contact area of footing. The maximum displacement was noticed at 33.34 to 41.67 Hz. The maximum displacement amplitude respons
... Show MoreIn this study a polymeric composite material was prepared by hand
lay-up technique from epoxy resin as a matrix and magnesium oxide
(MgO) as a reinforcement with different weight fraction (5,10,15,
and 20)% to resin. Then the prepared samples were immersed under
normal condition in H2So4(1 M) solution, for periods ranging up to
10 weeks. The result revealed that the diffusion coefficient
decreasing as the concentration of MgO increase. Also we studied
Hardness for the prepared samples before and after immersion. The
result revealed that the hardness values increase as the concentration
of MgO increase, while the hardness for the samples after immersion
in H2SO4 dec