The zirconia ceramic restoration (ZCR) is used as substitutes for the metal-ceramic restoration. Clinical studies demonstrating of ZCRs showed a high fracture incidence of veneering layer than metal-ceramic restorations. This attributed to the low bond strength of zirconia to veneering ceramic as a result of lacking of glass content in its matrix. Surface treatment was proposed to improve the bonding strength between zirconia and veneering ceramic. Several studies revealed that some treatment such as airborne particle abrasion (APA) is responsible for generating chipping of veneering ceramic. The study aimed to develop a new zirconia coatings to increase bonding strength between zirconia substrate and veneering porcelain. Three groups of 150 zirconia specimens (discs, rods and crowns) were divided according to the type of surface treatments; Group M1 designated unsintered zirconia specimens coated with a mixture of glaze porcelain powder and partially-sintered zirconia powder prepared at 1100 °C with two particle sizes; A (26 ± 0.3 μm) and size B (47 ± 0.5 μm), group M2 was coated with mixture of ceramic liner paste and same selected particle sizes of partially-sintered zirconia powders. The coated groups (M1 and M2) subdivided according to powder sizes into M1A, M1B, M2A and M2B. APA group (as control) of sintered zirconia specimens abraded with 50 μm aluminium oxide powder. Surface area roughness (Sa) was measured by surface texture analyser. Surface morphology and elemental composition were analysed by scanning electron microscope (SEM). Crystallographic phases were identified by X-ray diffraction (XRD). The coefficient of thermal expansion (CTE) was assessed by a thermomechanical analyser. For shear bond strength (SBS) test was evaluated by a universal testing machine (UTM). The fracture strength (FS) test prepared and measured by Cercon CAD/CAM system and UTM. Fractographic analysis for SBS and FS were examined by a stereomicroscope and SEM. For each test and measurement, 10 specimens were used per group. Finite element analysis (FEA) was used to simulate and predict the iv stress distributions of the static oblique load in coated and non-coated zirconia crown models. The collected data were analysed by one-way ANOVA and Tukey HSD test at (P<0.05). Surface roughness results showed significant differences among all groups (P<0.000). The M1B group exhibited a higher Sa value (10.33 ± 0.59 μm) among the tested groups. XRD analysis showed tetragonal and monoclinic phases in the control group while only tetragonal was detected in the coated groups. The SBS values for coated groups were higher than the control group. The M1B group showed higher and significant differences in SBS value (37.54 ± 4.38 MPa) among other tested groups (P<0.05). The FS test indicated that coated M1B group (647.92 ± 97.33 N) higher than the other groups (P<0.00). FEA showed the coated crown models have lower stress level than the non-coated model. The new coating (M1B) by airbrush spray technique considered as an alternative way to APA treatment to improve the bond strength of zirconia substrate to veneering ceramic and indicating as an applicable surface treatment for improving the clinical performance of the coated ZCR.
Background: The relation between insulin resistance ,leptin levels and other hormones in women with polycystic ovary syndrome(PCOS) is still controversial.Metformin therapy is proved effective in reducing insulin resistance and also in some studies it was seen to be effective in reducing leptin levels.
Al- Kindy Col Med J 2012 ; Vol .8 No. (2) p: 65
Objective: to study the effect of metformin on reducing leptin levels and enhancing ovulation in PCOS women.
Methods:metformin 500mg 3 times daily for 3 months was was given to 36 women
with proved PCOS, in addition to that, other parameters were included.
Results:28 women out of 36(77.78%) showed an evidence of ovulation ovulation after 3 months of metformin therapy(p<0.01)
Background: Alternative natural therapy by plants extracts had opened wide door for the use of natural products as an alternative therapy instead of many antibiotics and drugs , which had many harmful side effects.Also, an increased interest has been centered on the industrial wastes, especially plant raw materials which contain phenols (e.g. Pomegranate peel and Bay leaves) which is a sources of natural antioxidants ,which are on the contrary of synthetic antioxidants that had restrict use due to their health risks , carcinogenesis and toxicity .
Objectives :This study was done to fi
... Show MoreThe present study was conducted to investigate effect of prey type on the relationship between age of females of Macrocyclops albidus and reproductive performance, which included each of mean number of nauplii, age at first brood, and age at first clutch. Results revealed that the correlation coefficient between the age at first brood and clutch and age of females fed on Artemia was significant P <0.05, being 0.65 and 0.81 respectively, while the correlations were not significant P>0.05 in females fed on mosquito larvae (Culex quinquefasciatus) and Paramecium nauplii. It was also found that the correlation coefficients between mean number of the nauplii and longevity in M. albidus were significant P<0.05 whereas, the correlations were not s
... Show MoreVisible-light photodetectors constructed Fe2O3 were manufactured effectively concluded chemical precipitation technique, films deposited on glass substrate and Si wafer below diverse dopant (0,2,4,6)% of Cl, enhancement in intensity with X-ray diffraction analysis was showed through favored orientation along the (110) plane, the optical measurement presented direct allowed with reduced band gap energies thru variation doping ratio , current–voltage characteristics Fe2O3 /p-Si heterojunction revealed respectable correcting performance in dark, amplified by way of intensity of incident light, moreover good photodetector properties with enhancement in responsivity occurred at wavelength between 400 nm and 470 nm.
Abstract
This research aims to know the effect of job burnout in the worker’s performance. The researcher presented a theoretical basis for job burnout and the worker's performance. In order to achieve the objectives of the research, a hypothesis was drawn up that determines the nature of the relationship between the independent variable of job burnout and its dimensions (reduced personal accomplishment, depersonalization, Emotional Exhaustion) and variable dependent performance of workers dimensions (productivity, job satisfaction, organizational commitment, creativity), And to represent the volume of this community according to (de Morgan, D. Morgan) glo
... Show MoreBackground: Asthma is a common chronic disease in children in which the body’s airways swell, preventing the lungs from filling with air, there are many different inflammatory cells involved in asthma which can synthesize and release cytokines which are recognized to be important in chronic inflammation and play a critical role in the inflammatory response. Objectives: to assess the local effect of ICS on oral tissue by measuring Interlukine-12 level and Candida albicans colony in saliva among12 year's old asthmatic children who were collected from AL- Zahra Center Advisory for Allergy and Asthma, and compares them with non-asthmatic children of the same age and gender.Type of the study: Cross –sectional study.Methods: The total samp
... Show MoreIn situ gel can be defined as a polymer solution administered as a liquid and when exposed to some physiologic condition such as thepH, ionic, temperature modulation or solvent and UV induced gelation undergo to phase transition to a semisolid gel. Ketotifenfumarate belongs to the histamine H1 receptor antagonists, and Ketotifen fumarate is used in the treatment of allergic conditions likeconjunctivitis and rhinitis. This work aims to study the natural polymer effects (xanthan gum,gellan gum) on the properties of pH-trigger in situ ocular gel, then compared the drug-releasing rate of optimized formula with the market ketotifen eye drop. Eightformulations (F1-F8) were prepared using different concentrations of xanthan gum, gellan gum with ca
... Show MoreAn experimental and numerical investigation of the effect of using two types of nanofluids with suspending of (Al2O3 and CuO) nanoparticles in deionized water with a volume fraction of (0.1% vol.), in addition to use three types of fin plate configurations of (smooth, perforated, and dimple plate) to study the heat transfer enhancement characteristics of commercial fin plate heat sink for cooling computer processing unit. All experimental tests under simulated conditions by using heat flux heater element with input power range of (5, 16, 35, 70, and 100 W). The experimental parameters calculated are such as water and nanofluid as coolant with Reynolds number of (7000, 8000, 9400 and 11300); the air
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