The Effect of Root Canal Cleansing on the Retention of Glass Fiber-reinforced Posts

Esthetic glass fiber-reinforced posts are being used more often. The most commonly reported complication associated with these posts is debonding. Dentine conditioning with solutions such as EDTA or MTAD results in removal of smear layer and might improve the retention of posts to root canal dentin. Therefore, the purpose of this study was to investigate the effect of cleansing the post space with MTAD or EDTA on the bond strength of glass fiber-reinforced posts, when cemented with self-adhesive resin cement. Forty-five (n=15) extracted human premolar teeth were sectioned at the cemento-enamel junction to obtain root length of fifteen millimeters. Endodontic instrumentation and obturation was performed. Post space was prepared to a length of ten millimeters. Post spaces were irrigated using one of two solutions: MTAD for five minutes and 17% EDTA for one minute. No irrigation was used in the control group. After irrigation, excess moisture was removed and posts were cemented with RelyX Unicem. Retention of posts was evaluated with pull-out test using universal testing machine (0.5 mm/min) to pull the posts from the teeth. Maximum load-to-failure was recorded. One-way analysis of variance was used for the statistical analysis (α=.05). Dislodged posts were examined at 8X magnification to determine the mode of failure. Mean bond strength (N) for the MTAD, EDTA and control group were 146.7, 142.8 and 151.4 respectively. The difference among the groups was not statistically significant (α\u3e.05). Most dislodged posts exhibited mixed mode of failure. Based on these observations, it was concluded that the use of either EDTA or MTAD as a final rinse prior to post cementation does not influence the retention of glass fiber-reinforced posts, when cemented with self-adhesive resin cement

Solar array fed synchronous reluctance motor driven water pump : an improved performance under partial shading conditions

An improved performance of a photovoltaic (PV) pumping system employing a synchronous reluctance motor (SynRM) under partial shading conditions is proposed. The system does not include the dc-dc converter that is predominantly being utilized for maximizing the output power of the PV array. In addition, storage batteries are also not contained. A conventional inverter connected directly to the PV array is used to drive the SynRM. Further, a control strategy is proposed to drive the inverter so that the maximum output power of the PV array is achieved while the SynRM is working at the maximum torque per Ampere condition. Consequently, this results in an improved system efficiency and cost. Moreover, two maximum power point tracking (MPPT) techniques are compared under uniform and partial shadow irradiation conditions. The first MPPT algorithm is based on the conventional perturbation and observation (P&O) method and the second one uses a differential evolution (DE) optimization technique. It is found that the DE optimization method leads to a higher PV output power than using the P&O method under the partial shadow condition. Hence, the pump flow rate is much higher. However, under a uniform irradiation level, the PV system provides the available maximum power using both MPPT techniques. The experimental measurements are obtained to validate the theoretical work

Clinical and Laboratory Manifestations of Yemeni Patients with Systemic Lupus Erythematosus

Objectives: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterised by multi-systemic involvement. This is the first study undertaken to determine the relationships between serological marker positivity and age, gender, signs and symptoms, risk factors and the treatment of SLE in Yemen. Methods: We investigated the cases of 149 patients with SLE admitted to Al-Thawra Hospital in Sana’a city between November 2009 and November 2010. Of the 149 patients, females represented 75.2% and males, 24.8%. Results: The most frequent presenting signs and symptoms were fatigue (84.6%), fever (81.9%), arthropathy (81.2%), anaemia (64.4%), photosensitivity (54.4%), renal involvement (53%), malar rash (52.3%), and alopecia (49%). Antinuclear antibodies (ANA) were detected in 95.3% of the patients and were associated significantly with most clinical presentations, except weight loss, hypertension and serositis. Anti-ds deoxyribonucleic acid (anti-dsDNA) was detected in 59.7% of the patients, and was associated significantly with fever and fatigue. Anti-Smith (anti-Sm) antibodies were detected in 27.5% of the patients, but were not significantly associated with all clinical presentations. Social stress was the most important risk factor for inducing SLE, with an odds ratio (OR) of 6.0, followed by common exposure to sunlight (OR = 2.2). Conclusion: In this study, SLE was more prevalent among females and young adults. The clinical presentation was characterised by a high incidence of fatigue and fever, and a low incidence of oral ulcers and serositis. ANA was associated with most clinical presentations except weight loss, hypertension, and serositis. AntidsDNA antibodies were most frequently associated with fever, fatigue and hypertension. There was no significant association of the anti-Sm antibodies with any clinical presentations

The al-ʿUlā–al-Wajh Survey Project : The 2013 Reconnaissance Season

Peer reviewe

Modelling and design methodology of an improved performance photovoltaic pumping system employing ferrite magnet synchronous reluctance motors

This paper proposes a novel photovoltaic water pumping system (PVWPS) with an improved performance and cost. This system doesn’t contain a DC-DC converter, batteries nor rare-earth motors. Removing the aforementioned components will reduce the whole cost and increase the reliability of the system. For enhancing the performance of the PVWPS, a ferrite magnet synchronous reluctance motor (FMSynRM) is employed. Besides, the motor inverter is utilized to drive the motor properly and to extract the maximum available power of the PV system. This is performed using a suggested control strategy that controls the motor inverter. Furthermore, to show the effectiveness of the proposed PVWPS, the performance of the proposed system is benchmarked with a PVWPS that is employing a pure SynRM. Moreover, the complete mathematical model of the system components and the control is reported. It is proved that the flow rate employing the proposed system is increased by about 29.5% at a low irradiation level (0.25 kW/m2) and 15% at a high irradiation level (1 kW/m2) compared to the conventional solar system using a pure synchronous reluctance motor (SynRM). An experimental laboratory test bench is built to validate the theoretical results presented in this research work. Good agreement between the theoretical and the experimental results is prove

Simulation-based coyote optimization algorithm to determine gains of PI controller for enhancing the performance of solar PV water-pumping system

In this study, a simulation-based coyote optimization algorithm (COA) to identify the gains of PI to ameliorate the water-pumping system performance fed from the photovoltaic system is presented. The aim is to develop a stand-alone water-pumping system powered by solar energy, i.e., without the need of electric power from the utility grid. The voltage of the DC bus was adopted as a good candidate to guarantee the extraction of the maximum power under partial shading conditions. In such a system, two proportional-integral (PI) controllers, at least, are necessary. The adjustment of (Proportional-Integral) controllers are always carried out by classical and tiresome trials and errors techniques which becomes a hard task and time-consuming. In order to overcome this problem, an optimization problem was reformulated and modeled under functional time-domain constraints, aiming at tuning these decision variables. For achieving the desired operational characteristics of the PV water-pumping system for both rotor speed and DC-link voltage, simultaneously, the proposed COA algorithm is adopted. It is carried out through resolving a multiobjective optimization problem employing the weighted-sum technique. Inspired on theCanis latransspecies, the COA algorithm is successfully investigated to resolve such a problem by taking into account some constraints in terms of time-domain performance as well as producing the maximum power from the photovoltaic generation system. To assess the efficiency of the suggested COA method, the classical Ziegler-Nichols and trial-error tuning methods for the DC-link voltage and rotor speed dynamics, were compared. The main outcomes ensured the effectiveness and superiority of the COA algorithm. Compared to the other reported techniques, it is superior in terms of convergence rapidity and solution qualities

Fuzzy Fractional-Order PID Controller for Fractional Model of Pneumatic Pressure System

This article presents a fuzzy fractional-order PID (FFOPID) controller scheme for a pneumatic pressure regulating system. The industrial pneumatic pressure systems are having strong dynamic and nonlinearity characteristics; further, these systems come across frequent load variations and external disturbances. Hence, for the smooth and trouble-free operation of the industrial pressure system, an effective control mechanism could be adopted. The objective of this work is to design an intelligent fuzzy-based fractional-order PID control scheme to ensure a robust performance with respect to load variation and external disturbances. A novel model of a pilot pressure regulating system is developed to validate the effectiveness of the proposed control scheme. Simulation studies are carried out in a delayed nonlinear pressure regulating system under different operating conditions using fractional-order PID (FOPID) controller with fuzzy online gain tuning mechanism. The results demonstrate the usefulness of the proposed strategy and confirm the performance improvement for the pneumatic pressure system. To highlight the advantages of the proposed scheme a comparative study with conventional PID and FOPID control schemes is made

Knowledge and Attitude of Saudi Arabian School Teachers with Regards to Emergency Management of Dental Trauma

Injury to both the primary and the permanent dentitions and their supporting structures is one of the most common dental problems seen in children.  School is one of the locations with greatest prevalence of occurrence of traumatic dental injuries.  School teachers play important role in prevention of dental trauma and improving its prognosis. The present study was undertaken to assess knowledge and attitudes regarding emergency management of dental trauma, first aid for avulsed tooth and influence of dental education among school teachers in Abha city. METHODS: The participants were 100 school teachers from Abha city and were interviewed using a questionnaire regarding management of dental trauma.  The completed proformas was collected and the result was statistically analyzed to know the knowledge and attitudes regarding emergency management of dental trauma. CONCLUSIONS: Majority of school staff had little knowledge related to handling of traumatic dental injuries and emergency management of avulsed permanent teeth in school children. Majority of school teachers were eager to have knowledge regarding dental trauma through continues dental education programs and workshops.  First aid training increases knowledge about dental trauma and should be included in the course curriculum of teachers training program

Numerical estimation and experimental verification of optimal parameter identification based on modern optimization of a three phase induction motor

The parameters of electric machines play a substantial role in the control system which, in turn, has a great impact on machine performance. In this paper, a proposed optimal estimation method for the electrical parameters of induction motors is presented. The proposed method uses the particle swarm optimization (PSO) technique. Further, it also considers the influence of temperature on the stator resistance. A complete experimental setup was constructed to validate the proposed method. The estimated electrical parameters of a 3.8-hp induction motor are compared with the measured values. A heat run test was performed to compare the effect of temperature on the stator resistance based on the proposed estimation method and the experimental measurements at the same conditions. It is shown that acceptable accuracy between the simulated results and the experimental measurements has been achieved