Comparative evaluation of bioactive cements on biomimetic remineralization of dentin

This study was designed to quantitatively compare the presence of apatite peaks on demineralized dentin to induced bio-mimetically by bioactive commercial materials. Dentin slice specimens (n=6) were prepared and demineralized by by17% EDTA for 2 hours. Each disks materials (Theracal, Biodentine, CPP-ACP) were freshly prepared and was maintained in close contact with a demineralized dentin specimen immersed in PBS solution during one week. To evaluation of bioactivity, cements disks (n=6) were prepared from each material and immersed in PBS solution for one week. The bioactivity and remineralization ability was evaluated using FTIR spectroscopy and Scanning Electron Microscopy. The Ca/P ratio of the surface of dentin and cements disks were compared with one -way ANOVA, independent T test and Duncan test (?=0.05). Ca/P weight ratio of Biodentine (187.5) was significantly higher than Theracal (10.10) and Theracal higher than CPP-ACP (0.37) (P=0.008). Demineralized dentin in contact with Test materials, indicated Ca and P peak after 7 days, but not showed statistically differences between the groups (P=0.08). The outcome revealed that bioactive cements and CPP-ACP had bioactivity capability during one week. Biodentine had higher bioactivity between others. Demineralized dentin could be remineralized with bioactive materials

Viscous interfacial layer formation causes electroosmotic mobility reversal in monovalent electrolytes

We study the ion density, shear viscosity and electroosmotic mobility of an aqueous monovalent electrolyte at a charged solid surface using molecular dynamics simulations. Upon increasing the surface charge density, ions are displaced first from the diffuse layer to the outer Helmholtz layer, increasing its viscosity, and subsequently to the hydrodynamically stagnant inner Helmholtz layer. The ion redistribution causes both charge inversion and reversal of the electroosmotic mobility. Because of the surface-charge dependent interfacial hydrodynamic properties, however, the charge density of mobility reversal differs from the charge density of charge inversion, depending on the salt concentration and the chemical details of the ions and the surface. Mobility reversal cannot be described by an effective slip boundary condition alone – the spatial dependence of the viscosity is essential

Semantically Intelligent Distributed Leader Election (SIDLE) Algorithm for WSAN Part of IoT Systems

This paper introduces the deployment of a group of Wireless Sensor and Actuator Network (WSAN) part of Internet of Thing (IoT) systems in rural regions deployed by a drone dropping sensors and actuators at a certain position as a mesh of a hexagonal form. Nodes are heterogeneous in hardware and functionality thus not all nodes are able to transfer data directly to the base station. Primitive ones are only capable of collecting local data. However, ones that are more sophisticated are equipped with long-range radio telemetry and more computational power. Power optimization is one of the crucial factors in designing WSANs. Total power consumption must be minimized, as sensors are self-managed. It is not feasible to collect sensors on time bases and recharge the batteries. Therefore, energy consumption optimization and harvesting green energy are other factors that are considered. In this regard, protocols are designed in a way to support such requirements. The preprocessed data are first collected and combined by the leaders at each hexagonal cell. Then, the information packets are sent to the head clusters. Consequently, head clusters reprocess the received information and depict a better global view of the zone, using a variety of the received information. Finally, the processed information is sent to the nearest base station or a mobile drone.Comment: The First International Conference of Smart City, 2019, Apadana University, Shiraz, Iran https://www.civilica.com/Paper-SMARTCITYC01-SMARTCITYC01_100.htm

Comparing the Effect of Topical Acidulated Phosphate Fluoride on Micro- Hardness of Two Fissure Sealants and One Flowable Composite

Objective: Probable effect of fluoride containing materials like APF on sealants is very important. The purpose of this study is to assess the effect of frequent application of APF (1.23%) on the surface microhardness of two fissure sealants and one flowable composite.Methods: In this experimental study, 81 specimens of two fissure sealants and one flowable composite were prepared, using special polymer mold in three groups of 27 including unfilled resin sealant (Fissurite F, Voco), filled resin sealant (Fissurit FX, Voco) and one flowable composite (Arabesk Flow, Voco). Then, these three groups were divided into three sub groups of 9 as follows: Group 1, 4, 7 (control): No treatment- Group 2, 8, 5: Single application using APF- Group 3, 6, 9: Six times application using APF. The APF was applied on the experimental specimens every time  for 4 minutes. Then, the samples were stored in the distilled water. Finally, the surface microhardness of the sealants was measured using Vickers test. The statistical analysis was performed by 2-way ANOVA & One-way ANOVA tests.Results: Type of materials (without filler, containing filler and flowable composite) was effective on the surface microhardness and the difference between three types of materials was statically significant (p<0.001).Unfilled fissure sealants, showed minimum surface microhardness and flow able composite showed maximum surface microhardness. Also, the frequency of gel use (once or many times), had no effect on the average surface microhardness of the materials under review (p>0.05).Conclusion: All three materials were resistant to the destructive effects of APF gel and it did not make a significant microhardness changes

Numerical and experimental study on the steady cone-jet mode of electro-centrifugal spinning

This study focuses on a numerical investigation of an initial stable jet through the air-sealed electro-centrifugal spinning process, which is known as a viable method for the mass production of nanofibers. A liquid jet undergoing electric and centrifugal forces, as well as other forces, first travels in a stable trajectory and then goes through an unstable curled path to the collector. In numerical modeling, hydrodynamic equations have been solved using the perturbation method—and the boundary integral method has been implemented to efficiently solve the electric potential equation. Hydrodynamic equations have been coupled with the electric field using stress boundary conditions at the fluid-fluid interface. Perturbation equations were discretized by a second order finite difference method, and the Newton method was implemented to solve the discretized non-linear system. Also, the boundary element method was utilized to solve electrostatic equations. In the theoretical study, the fluid was described as a leaky dielectric with charges only on the surface of the jet traveling in dielectric air. The effect of the electric field induced around the nozzle tip on the jet instability and trajectory deviation was also experimentally studied through plate-plate geometry as well as point-plate geometry. It was numerically found that the centrifugal force prevails on electric force by increasing the rotational speed. Therefore, the alteration of the applied voltage does not significantly affect the jet thinning profile or the jet trajectory

Effect of Different Topical Agents on Remineralization of Early Enamel Lesion– an in vitro Study

Objective: This study aimed to compare the effect of using Casein phosphopeptide – amorphous calcium phosphate (CPP-ACP) paste, Remin-Pro and Fluoride Varnish on remineralization of  enamel lesions.Methods: In this experimental-in vitro study, 60 intact premolars and molars were used and flat enamel surfaces were prepared. The specimens were divided into 6 groups (N=10). After primary DIAGNOdent value measurement and a four-day immersion in demineralizing solution, the DIAGNOdent value were measured. Groups 1, 2 and 3 were treated by Fluoride varnish, CPP-ACP and Remin-Pro respectively, according to the manufacturer instruction and their DIAGNOdent value was read. Groups 4, 5, and 6 were treated by Fluoride varnish, CPP-ACP and Remin-Pro for 1  month (8 hours a day), respectively, and their DIAGNOdent value was measured. Then the specimens of these three groups were demineralized and pH cycled and their DIAGNOdent values were recorded. The data were analyzed by One-way analysis of variance (ANOVA) and repeated measures ANOVA.Results: After a one-month treatment, the DIAGNOdent value significantly decreased in groups 4, 5, and 6 in comparison to the manufacturer instruction (p<0.001). ANOVA test indicated that decrease mean value of DIAGNOdent value was significantly higher for Remin-Pro and CPP-ACP groups than Fluoride varnish group, from entrance time to the study to re-demineralization stage (p<0.001). Conclusion: All the three materials showed a statistically significant amount of remineralization after repeated application but the CPP-ACP and Remin pro were more resistant to  redemineralization and pH cycling

Numerical and experimental investigation on static electric charge model at stable cone-jet region

In a typical electro-spinning process, the steady stretching process of the jet beyond the Taylor cone has a significant effect on the dimensions of resulting nanofibers. Also, it sets up the conditions for the onset of the bending instability. The focus of this work is the modeling and simulation of the initial stable jet phase seen during the electro-spinning process. The perturbation method was applied to solve hydrodynamic equations, and the electrostatic equation was solved by a boundary integral method. These equations were coupled with the stress boundary conditions derived appropriate at the fluid-fluid interface. Perturbation equations were discretized by the second-order finite difference method, and the Newton method was implemented to solve the discretized nonlinear system. Also, the boundary element method was utilized to solve the electrostatic equation. In the theoretical study, the fluid is described as a leaky dielectric with charges only on the jet surface in dielectric air. In this study, electric charges were modeled as static. Comparison of numerical and experimental results shows that at low flow rates and high electric field, good agreement was achieved because of the superior importance of the charge transport by conduction rather than convection and charge concentration. In addition, the effect of unevenness of the electric field around the nozzle tip was experimentally studied through plate-plate geometry as well as point-plate geometry

Experimental and numerical study on isolated and non-isolated jet behavior through centrifuge spinning system

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments.There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found

Comparative evaluation of incorporation calcium silicate and calcium phosphate nanoparticles on biomimetic dentin remineralization and bioactivity in an etch-and-rinse adhesive system

This study aimed to evaluate the remineralization potential and bioactivity of adhesives, containing amorphous calcium phosphate (ACP) and calcium silicate (CS) nanoparticles (NPs). In this study, dentin slices (n=60) were prepared and etched with phos