Abstract Background: The daily usage of maxillofacial prostheses causes them to mechanically deteriorate with time. This study was aimed to evaluate the reinforcement of VST50F maxillofacial silicone by using yttrium oxide (Y2O3) nanoparticles (NPs) to resist aging and mechanical deterioration. Materials and Method: Y2O3 NPs (30–45nm) were loaded into VST50F maxillofacial silicone in two weight percentages (1 and 1.5 wt%), which were predetermined in a pilot study as the best rates for improving tear strength with minimum increase in hardness values. A total of 120 specimens were prepared and divided into the control and experimental groups (with 1 and 1.5 wt% Y2O3 addition). Each group included 40 specimens, 10 specimens for each parameter tested (i.e., tear strength, surface roughness, hardness, tensile strength and elongation percentage). Specimens were artificially aged in a weathering chamber for 150 h and then tested. Data were analyzed by ANOVA and Tukey’s honestly significant difference (HSD). Statistical significance was set to P ≤ 0.05. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were also conducted. Results and Discussion: SEM results showed that Y2O3 NPs were distributed well within the silicon matrix. FTIR results indicated that the NPs were physically dispersed within VST50F silicone without chemical interaction. After 150 h of accelerated artificial aging, adding Y2O3 NPs significantly increased the tear strength, hardness, surface roughness, and elongation percentage. Tensile strength increased non significantly. Conclusion: Adding Y2O3 NPs as fillers improved the mechanical properties of artificially aged maxillofacial silicone elastomer. Keywords: maxillofacial silicone, Y2O3, nanoparticles, fillers, artificial aging.
The presented study investigated the scheduling regarding jobs on a single machine. Each job will be processed with no interruptions and becomes available for the processing at time 0. The aim is finding a processing order with regard to jobs, minimizing total completion time , total late work , and maximal tardiness which is an NP-hard problem. In the theoretical part of the present work, the mathematical formula for the examined problem will be presented, and a sub-problem of the original problem of minimizing the multi-objective functions is introduced. Also, then the importance regarding the dominance rule (DR) that could be applied to the problem to improve good solutions will be shown. While in the practical part, two
... Show MoreThis study aimed at identifying how children express the emerging coronavirus in general and according to their age groups (4-13 years) by analyzing 91 of their drawings published online, using the descriptive content analytical approach. The results showed that children's artistic expression of the virus came according to the concepts and ideas they carried about the virus for the age groups of (4-7 years) and (7-9 years), while it came according to visual perception for age groups (9-11 years), and from (11-13) years. Also, most children were aware about the presence of the virus and its widespread around the world, but (99%) of them do not realize the seriousness of the virus. It was confirmed that between (25-34%) of children were su
... Show MoreThis paper aims to improve the voltage profile using the Static Synchronous Compensator (STATCOM) in the power system in the Kurdistan Region for all weak buses. Power System Simulation studied it for Engineers (PSS\E) software version 33.0 to apply the Newton-Raphson (NR) method. All bus voltages were recorded and compared with the Kurdistan region grid index (0.95≤V ≤1.05), simulating the power system and finding the optimal size and suitable location of Static Synchronous Compensator (STATCOM)for bus voltage improvement at the weakest buses. It shows that Soran and New Koya substations are the best placement for adding STATCOM with the sizes 20 MVAR and 40 MVAR. After adding STATCOM with the sizes [20MVAR and 40MV
... Show MoreThe estimation of the regular regression model requires several assumptions to be satisfied such as "linearity". One problem occurs by partitioning the regression curve into two (or more) parts and then joining them by threshold point(s). This situation is regarded as a linearity violation of regression. Therefore, the multiphase regression model is received increasing attention as an alternative approach which describes the changing of the behavior of the phenomenon through threshold point estimation. Maximum likelihood estimator "MLE" has been used in both model and threshold point estimations. However, MLE is not resistant against violations such as outliers' existence or in case of the heavy-tailed error distribution. The main goal of t
... Show MoreThe Arab Islamic Manuscripts in the science libraries humanly global heritage in different types of knowledge and science, as they were not confined to a particular flag but extended to include all kinds of science, and to facilitate the knowledge of these types of manuscripts has been necessary to operate them indexed in most libraries , because it is important in determining the size of those manuscripts and set them up and facilitate the work of the investigators, as well as the significance of indexing to know printed manuscripts in order to avoid repetition of the publication of the manuscript more than once, especially if the deployment is to be characterized by accurate scientific integrity and following the origins of the scienti
... Show MoreThis study has been conducted to know the level of microbial ( bacteria and fungi) contamination in 5 types of biscuits from local markets of Baghdad city. Fifty samples (ten sample for each kind of biscuit) were studed,Two are local,others are Iranian,Turkish,and Holandies. The following results have been achieved :1. The highest number of bacteria was 21.6×103 cell/g in Iranian biscuit while the lowest number was 14.3× 103 cell/g in local biscuit No.1 . The highest number of fungi was 16×103 colony/g and the lowest number was 5.3×103 colony/g in the Iranian and the local biscuit No.1,respectively.2. Staphylococcus aureus was the major bacteria appeared at highest level of 100% in Turkish biscuit. The lowest percentage was found in H
... Show MoreThe childhood of the most important stages throughout the human and which have been more vulnerable to various factors surrounding it and with the scientific and cognitive development in all fields surfaced many psychological phenomena that play a large role in influencing children and their behavior trends is the susceptibility of the lure of psychological phenomena which plays a major role in the social attitudes of individuals it may not be predictable so that individuals vary in between them in terms of vulnerability Balasthoa You do this only _bl that the same individual at different influenced Balasthoa different depending on the positions and this was research to achieve its objectives and that are known:
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The present study was designed to evaluate the immunological status in a sample of Iraqi males with primary infertility and them age range18-55 years, who were attending the Centre of Infertility and in vitro Fertilization (Kamal Al-Samaraie Hospital, Baghdad) during the period December 2008 – April 2009. They were divided into three groups; 40 patients with anti-sperm antibodies (ASA), 20 patients with Asthenozoospermia (AST) and 20 patients with azoospermia (AZO). In adition to20 fertile males was as control group. The parameters of evaluations were standard seminal fluid analysis, anti-sperm antibodies and anti-mitochondrial antibodies in serum, Therefore, two types of samples were collected from each subject; seminal fluid and blood.
... Show MoreThe current research is concerned with a pragmatic study of attack and defense acts that are used by President Donald Trump in the American Presidential Debate in 2020. Attack is an attempt to harm or defeat someone, and it is a bold message that the speaker or attacker does not like or disagree with the other antagonist. On the contrary, defense means a person responds to an attack of his or her opponent. After an attack, the politician either negates or fact-checks claims made by his opponents or tries to set the record straight. By the end of the study, it is expected to answer the following questions: What are the most frequent strategies of attack and defense that utilized by President Trump to formulate his speech? What are the reason
... Show MoreStarting from bis (4,4'-diamino phenoxy) ethan(1), a variety of phenolicschiff bases (methylolic, etheric, epoxy) derivatives have been synthesized. All proposed structure were supported by FTIR, 1H-NMR, 13C-NMR Elemental analysis, some derivatives evaluated by thermal analysis (TGA).