The dynamic thermomechanical properties, sealing ability, and voids formation of an experimental obturation hydroxyapatite-reinforced polyethylene (HA/PE) composite/carrier system were investigated and compared with those of a commercial system [GuttaCore (GC)]. The HA/PE system was specifically designed using a melt-extrusion process. The viscoelastic properties of HA/PE were determined using a dynamic thermomechanical analyser. Human single-rooted teeth were endodontically instrumented and obturated using HA/PE or GC systems, and then sealing ability was assessed using a fluid filtration system. In addition, micro-computed tomography (μCT) was used to quantify apparent voids within the root-canal space. The data were statistically analysed using one-way anova and post hoc tests. The HA/PE composite exhibited important modulus and damping changes with an increase of temperature. The HA/PE system was more flexible than GC as the modulus of GC appeared to be significantly higher than that of HA/PE as a result of the high positive glass transition temperature (Tg). However, HA/PE and GC presented similar sealing abilities. In conclusion, because sealing ability and voids formation were comparable between the tested materials, the experimental HA/PE system may be considered a suitable alternative material for root-canal obturation. Moreover, HA/PE possesses specific viscoelastic behaviour and lower melting points, which may facilitate root-canal retreatments.
This paper examines the decolonizing methods used by Leslie Marmon Silko in her novel Ceremony (1977) to heal the indigenous people from the patriarchal traditions of the white hegemony. This study aims to emphasize the vulnerable responses of the Pueblo people to the memories of the clan and to highlight Silko’s methods to sustain the history and lifestyle of the indigenous people. Therefore, Silko’s novel can be situated historically and culturally within memory-studies. To analyze the contrasting behaviors of characters, this paper projects the relationship between the collective patriarchal doctrines and that of the individual within the framework of memory studies. Theories of Jan and Aleida Assmann are used here to explore the
... Show MoreHydrophobic silica aerogels were successfully preparation by an ambient pressure drying method from sodium silicate (Na2SiO3) with different pH values (5, 6, 7, 8, 9 and 10). In this study, acidic HCl (1M), a basic NH4OH (1M) were selected as a catalyst to perform the surface modification in a TMCS (trimethylchlorosilane) solution. The surface chemical modification of the aerogels was assured by the Fourier transform infrared (FTIR) spectroscopic studies. Other physical properties, such as pore volume and pore size and specific surface area were determined by Brunauer-Emmett- Teller (BET) method. The effect of pH values on the bulk density of aerogel. The sol–gel parameter pH value in the sol, have marked effects on the physical proper
... Show MoreCr2O3 thin films have been prepared by spray pyrolysis on a glass substrate. Absorbance and transmittance spectra were recorded in the wavelength range (300-900) nm before and after annealing. The effects of annealing temperature on absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constant and optical conductivity were expected. It was found that all these parameters increase as the annealing temperature increased to 550°C.
The importance of our research is that it examines the causes and sources of the security challenges in the internal security environment of the GCC countries, and aims to address the most important issues that are of great interest, namely, the issue of inter-GCC differences and addressing the issues of regional security for the Gulf region, After it is one of the most dynamic and more polarized areas for the emergence of threats and challenges because of the multiplicity of sources of threat and their complexity due to the specificity of the strategic environment and the negative repercussions it can have on the Gulf region, especially the issue of regional security of the Gulf Cooperation Council Which has become a magnet for competing i
... Show MoreObjectives of this project were to study the effect of 60% crude alcoholic extract of the seeds of cyperus esculentuson induced endometritis in the mice . The plant of cyperus esculentuswas extracted by preparing Alcoholic extract 60% . One hundred microliters of saline containing Escherichia coli (104cfu) was used to induce endometritis, by a single intracervicallyinjection, and endometritis developed after 2 days from injection. The mice were divided into five groups, The first group were treated with alcoholic extract of cyperus esculentusextract 150mg/kg body weight, the second group was treated with a daily 3mg per kg body weight of gentamicin given intra peritoneal,The third group was treated by 75mg/kg of cyperus esculentusextract an
... Show MoreThe research seeks to identify the dimensions of creative thinking and its impact on the re-engineering of hotel service operations by analyzing the correlation and impact between research variables as well as comparing the research sample The importance of the research comes from the need to motivate managers the importance of creative thinking among workers in the researched hotels because it is an essential part in the re-engineering of hotel services. To achieve this a questionnaire was designed containing (33) items that include the independent research variables (creative thinking) and the accredited (re-engineering the hotel service) and distributed to a sample of (50) individuals represented by (Commissioner Director, Dep
... Show MoreObjective: To evaluate the effectiveness of educational program on female students’ knowledge toward premenstrual syndrome.
Methodology: A quasi-experimental design study conducing on (140) student purposely in four secondary schools at Al-sadder city (70) student for study group and (70) for control group. The prevalence of PMS selected through American College of Obstetricians and Gynecologists (ACOG) (2015) criterias to select PMS students before program. The education program were set in four steps, the first step (pre-test) is to assess the knowledge , before the implementation of the program, the second step is implementing the program, following two steps post-test I and II between each test two weeks. Validity is determined
This research aims to introduce a new technique-off-site and self-form segmental concrete masonry arches fabrication, without the need of construction formwork or centering. The innovative construction method in the current study encompasses two construction materials forms the self-form masonry arches, wedge-shape plain concrete voussoirs, and carbon fiber-reinforced polymer (CFRP) composites. The employment of CFRP fabrics was for two main reasons: bonding the voussoirs and forming the masonry arches. In addition, CFRP proved to be efficient for strengthening the extrados of the arch rings under service loadings. An experimental test was conducted on four sophisticated masonry arch specimens. The research parameters were the Keystone thic
... Show MoreThe thermal performance of indirect expansion solar assisted heat pump, IX-SAHP, was investigated experimentally under Iraqi climate. An Indirect-Solar Assisted Heat Pump system was designed, built, instrumented and tested. Experimental tests were conducted by varying the controlling parameters to investigate their effects on the thermal performance of the IX-SAHP such as cooling water flow rate, heating water flow rate, ambient temperature and solar radiation intensity. The investigation covered values of cooling water flow rate of (2, 3, 4, 5 l/min) and heating water flow rate of (2, 3, 4, 5 l/min) under meteorological condition of Baghdad from November 2014 to January 2015.
The results indicated that the performance of the IX-
... Show MoreAbstract: Two different shapes of offset optical fiber was studied based on coreless fiber for refractive index (RI)/concentration (con.) measurement, and compare them. These shapes are U and S-shapes, both shapes structures were formed by one segment of coreless fiber (CF) was joined between two single mode (SMF) lead in /lead out with the same displacement (12.268µm) at both sides, the results shows the high sensitive was achieved in a novel S-shape equal 98.768nm/RIU, to our knowledge, no one has ever mentioned or experienced it, it’s the best shape rather than the U-shape which equal 85.628nm/RIU. In this research, it was proved that the offset form has a significant effect on the sensitivity of the sensor. Addi
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