Background: Thermocycling simulates the temperature dynamics in the oral environment. This in vitro study done to measure and compare the effect of thermocycling on the shear bond strength of stainless steel and sapphire brackets bonded to human enamel teeth using light cured orthodontic adhesive and debonded at various time, and to measure adhesive remnant index after debonding. Materials and Methods: one-hundred-twenty extracted upper first premolars for orthodontic reason were used in this study; depending on weather thermocycled or not, the sample was divided into two main groups, then within each group 30 teeth were used for stainless-steel brackets (Bionic®) and for sapphire brackets (Pure®). Both groups were subdivided into three groups (n = 10) according to the debond times: I: debond after 24 hour, II: debond after 7 days and III: debond after 30 days. Within 24 hr, half of the sample was thermocycled manually for 500 complete cycles between 5/55°C and the remaining sample was stored in distilled water at room temperature and water was changed daily until debond time for each group was performed. The adhesive remnant index was tested under 20X magnification lens using stereomicroscope. Results and Conclusions: Both bracket types demonstrated high shear bond strength values before thermocycling (P?0.05), whereas after 500 thermocycles, there were significant changes in shear bond strength resulted in marked reduction in the stainless steel brackets than in the sapphire brackets (P?0.05). Shear bond strength values increased with time for both stainless steel and sapphire brackets with and without thermocycling (P?0.05). The tendency of bond failure was increased at the bracket/adhesive interface rather than enamel/bracket interface in the stainless steel brackets whereas at the enamel/bracket interface rather than bracket/adhesive interface in the sapphire brackets.
Numerical simulation of charge density produced in plasma actuators is dependent upon the development of models dealing with electrical properties. The main aim of this work is to investigate the characteristics surface charge density and space charge density of DBD plasma actuator. A simple design of surface dielectric barrier discharge plasma actuator is used in the study. The discharge gas was N2:H2 mixture with applied voltage equal to 1.5 kV. A theoretical plasma model is used to establish the charge density details. Results show that surface charge density increased in value and spread in width alone the exposed electrode as the voltage increased and reached to the amplitude value.
The present paper is a qualitative descriptive study. It aims to examine the macro-cultural schemata addressing the concept of violence against women in Iraq from a cognitive linguistic point of view. To meet this objective, a number of Iraqi social caricatures have been selected from two popular and active Iraqi caricaturists, Odeh Al-Fahdawi and Nasser Ibrahim. The selection and the analysis of data have been achieved following the validity and reliability procedures and the ethical considerations. To meet this objective, Sharifian’s Model (2011) of Cultural Schemata has been adopted in data analysis. The study has concluded that the macro-cultural schemata regarding the concept of violence in the selected panels reveals that violenc
... Show MoreThe genus of Androctonus is widely distributed in Asia and Africa .It is found in Egypt, Palestine, Iran, Jordan, Syria, Saudi Arabia and Iraq. The present study is the first taxonomic study to describe Androctonus crassicauda (Oliver,1807) in Iraq .The genus Androctonus recognized by three main characters which are: color it is ranges from light brown to raddish to blackish brown to black, pedipalp (Chelae) is narrower than patella in adults, and pedipalp fingers with many denticles. Among other characters by which the genus can be distinguished by body hairs and, the rows of denticles on pedipalp fingers. The main morphological characters of the species are figured of And
... Show MoreThe present study aimed to investigated Giardia duodenalis in cattle in some different areas of Wasit province by using molecular study and verification of the genotype of Giardia duodenalis. Collected one hundred fecal samples from cattle, the result showed that the rate of infection was 83% (100) . DNA was extracted from the 100 positive samples from the cattle then amplified using the special tris-phosphatesomerase gene for genotyping A and B. The result of type A infection was (69%) and (45%) of the genotype B. The purpose of this study was to investigate the genotypes of cattle in Wasit province and compare them with previous sources at the NCBI data bank.
The ceiling of the midbrain has a couple of optic lobes which are prominent and used as an optic center that reflex what it receives from eye retina fibers. The histology of optic tectum has been studied in Iraqi fish Barbus luteus (Heckel) . It was found that the number of optic tectum were six main strata organized from the outside to the inside as follows : the stratum marginal (SM), the stratum opticum (SO), the stratum fibrosum et griseum superficialis (SFGS), the stratum griseum central (SGC), the stratum album central (SAC), the stratum periventricular (SPV), . the tow last strata consider deep layers on the optic tectum. It was noticed that the superficial strata was the first (SM), while the thickest strata was the four (SGC), whic
... Show MoreThis study provides a Key to the species of Cerceris Latreille, 1802 (Hymenoptera, Crabronidae, Philanthinae) that were collected from different areas in Iraq. This is followed by a distribution list, including total species which had been registered for Iraq. Also this study includes some observations about the species that were recorded in previous checklists.
This study deals with examining UCAS students’ attitudes in Gaza towards learning Arabic grammar online during the Corona pandemic. The researcher has adopted a descriptive approach and used a questionnaire as a tool for data collection. The results of the study have statistically shown significant differences at the level of "0.01" between the average scores of students in favor of the students of the humanities specializations. It has also been found that the students’ attitudes at the Department of Humanities and Media towards learning Arabic grammar online are positive. Additionally, the results revealed no statistical significant differences due to the variable of UCAS students’ scientific qualifications. The results stressed
... Show MoreThis research aimed to identify the structural model of the relationship between emotional creativity and self-efficacy among male and female students of the preparatory year at Tabuk University. The current study adopted the descriptive correlational approach, as it is appropriate to the nature of the study. The study tools contained (60) items that measure the relationship between emotional creativity and self-efficacy among the male and female students of the preparatory year at Tabuk University. The study sample was chosen by the stratified random method of the study community, where the study sample reached (183) male and female students of the preparatory year at the University of Tabuk. The results of the study showed that there a
... Show MoreBackground: Investigating dental health knowledge among children is important. Knowing what behaviors are right in relation to dental health does not guarantee that children will practice those behaviors. However, lack of knowledge and misconceptions about dental health may lead to behaviors that are harmful to teeth and gum. Baseline data on knowledge levels are required to determine which particular areas of dental health education are in need of improvement for high-risk children living in different geographical areas. This research was conducted to study the oral health status, dental knowledge and behavior in relation to two different cities, among children in Baghdad and Thamar (republic of Yemen) governorate. Materia
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