Comparison of Easydo Activator, Ultrasonic and Needle Irrigation Techniques on Sealer Penetration in Extracted Human Teeth

This study compared the effects of different irrigation systems on sealer penetration at the root apex. Forty-two single-rooted teeth were prepared and randomly divided into three groups (n = 14): group 1: needle irrigation (NI); group 2: passive ultrasonic irrigation (PUI); and group 3: Easydo Activator (EA). A solution of 3% sodium hypochlorite (NaOCl) was used for irrigation. Nine teeth in each group were filled with AH Plus sealer mixed with CY5 fluorescent dye and a single gutta-percha cone. The sealer penetration area, maximum penetration depth and percentage of sealer penetration at 5 mm and 1 mm from the apex were analyzed by confocal laser scanning microscopy (CLSM). The remaining 5 teeth in each group were subjected to test smear layer scores by scanning electron microscopy (SEM). The CLSM evaluation showed that increases in the area, depth and percentage of sealer penetration were detected at 1 mm and 5 mm from the root apex in the PUI group compared with the NI group, and greater increases were observed in the EA group (P < 0.05). The SEM experiment showed that the lowest scores for the smear layer and debris removal were achieved by the EA group when compared with the PUI and NI groups (P < 0.05). Our study supports EA was superior to PUI and NI regarding sealer penetration at the root apex during endodontic treatment, and it could provide a new technical idea for clinical root canal therapy.

Quasi-static perforation response of inter-ply hybrid polypropylene composites at various temperatures

This study is motivated by the lack of knowledge in the research of mechanical characterization of thermoplastic composites (TPCs) with additional fiber hybridization. To enhance the mechanical properties of long glass fiber-reinforced polypropylene (PP) composite, hybridization via alkaline-treated aramid and carbon fabrics is performed. High performance fabrics modified with 10 wt.% sodium hydroxide (NaOH) aqueous solution are incorporated into the PP composite as reinforcements. Herewith, four arrangements (hybrid composites) for two different reinforcements and two different stacking configurations and the monolithic composite are separately investigated in terms of quasi-static perforation behavior. Failure mechanisms are also evaluated at macro level by visual observations and micro scales through a scanning electron microscopy (SEM). The experimental results provide a basis for selecting fiber-enabled hybridization and lay-up configuration with improved perforation resistance. Moreover, the influence of test temperature is reported for three different values as 20°C, 60°C, and 100°C. Based upon the results, the maximum penetration force of hybrid configuration with single-layered aramid fabric reinforcements is approximately 15.5% higher than that of single-layered carbon fabric reinforcements at 60°C test temperature. It is further observed that the absorbed energy improves as the number of fabrics is increased in both aramid and carbon reinforcements. The test temperatures significantly affect the failure mechanisms of TPCs. A smaller damaged area at the penetrated faces of the hybrid structures is obtained by comparison with the monolithic TPCs.

Theoretical Study for the Calculation of Proton Range in Human Body Tissues

The main rationale for using charged particles in radiation therapy is the strong rise of energy loss (deposited dose) with maximum penetration depth ( Bragg peak) and rapid dose deposited behind the peak. Thus, a large dose can be applied to a deep seated tumor, with saving the surrounding normal tissues . Proton radiotherapy is nowadays an established method in the management of cancer diseases, although its availability is still limited to a few specialized centers. In this study, the range and the stopping power for proton interaction in the skeleton and intestine tissues, for an energy range from 0.01 to 300 MeV, was studied. The numerical calculations and analyses of Bethe Ziegler, along with CASP and SRIM software programs, were applied using Matlab program. The absorbed dose and the Bragg peak were calculated and presented as tables and figures .

Metformin hydrochloride entrapment in sorbitan monostearate for intestinal permeability enhancement and pharmacodynamics

Penetration enhancement of metformin hydrochloride via its molecular dispersion in sorbitan monostearate microparticles is reported. This represents basic philosophy to maximize its entrapment for maximum penetration effect. Drug dispersion in sorbitan monostearate with different theoretical drug contents (TDC) were prepared. Products showed excellent micromeritics and actual drug content (ADC) increased by increasing TDC. The partition coefficient of the drug products showed huge improvement. This indicates the drug entrapped in the polar part of sorbitan monostearate as a special image which effects on the drug release. The drug permeation profiles from the different products are overlapped with nearly equal permeation parameters. The permeation results suggested the main driving force for improving the drug paracellular pathway is its dispersion in sorbitan monostearate and is independent of ADC. Pharmacodynamic of the products showed a significant improvement than the drug alone at p ˂ 0.05. ANOVA test indicated the insignificant pharmacodynamic difference between the low, middle, and high ADC of the products. An excellent correlation founded between the drug permeation and pharmacodynamic precents. Drug permeation driving force via the paracellular pathway is its entrapment in sorbitan monostearate and independent on ADC. The technique is simple and the products had excellent micromeritics.

Comparative Evaluation of the Penetration Depth into Dentinal Tubules of Three Endodontic Irrigants

This study aimed to examine the penetration depth into dentinal tubules of some chelating agents. The 17% EDTA and two preparations containing surfactants (Smear Clear, Bioakt Endo) were tested. Surface tension and liquid viscosity were measured using a Dynamic Contact Angle Analyzer and a Haake rotational rheometer. To measure the penetration depth inside dentinal tubules, thirty maxillary central incisors were selected from a pool of extracted human permanent teeth and allocated to three experimental groups (10 samples each), as well as were mechanically shaped and cleansed with 5.25% NaOCl, followed by each of the chelators being labeled with 0.1 wt % Rhodamine B according to final irrigation protocol established. The samples were embedded in an epoxy resin, after which 200 μm thick transverse sections were obtained at 2, 5, and 8 mm from the apex with a saw microtome. The specimens were then observed using a confocal laser microscope (CLSM) and the penetration of the labeled solution was measured in every third of each sample. Statistical analysis was performed using ANOVA or Kruskal–Wallis tests according to the distribution of data, evaluated with the Shapiro–Wilk normality test. Viscosity and surface tension tests have shown that BioAKT Endo has the lowest values compared to EDTA and Smear Clear. The medium penetration depth did not significantly differ among the three irrigants, while it increased considerably from the apical to the coronal level in all groups. Additionally, the maximum penetration depth increased significantly from the apical to coronal level, while among groups, BioAKT Endo showed the highest values at the apical and middle level compared to the other irrigants. No significant differences were observed among the three groups in medium and maximum penetration depths when the entire root was considered. New irrigants containing surfactants show reduced surface tension and, in one case (BioAKT Endo), viscosity. The lowering of the surface tension allows for better penetration of liquids into dentinal tubules than EDTA alone, thus improving the cleaning of the root canal system.

Power Quality and Performance Analysis of Grid-Connected Solar PV System Based on Recent Grid Integration Requirements

The electrical energy demand is steadily growing, and hence, the integration of photovoltaic system to the distribution networks is also dramatically increasing though it has a significant effect on the network’s power quality. The purpose of this paper is to analyze the impact of solar PV integration on the power quality of distribution networks. The study is conducted using ETAP software, taking one of the radial distribution networks available in Bahir Dar city during the peak of connected loads which has the least voltage profile. Furthermore, the optimal location of the PV in the network is done using particle swarm optimization. Accordingly, the appropriate location of the PV system is determined to be the farthest end bus (bus 34). Also, the impact in terms of voltage and current harmonic distortion on the distribution feeder network is comparatively discussed by comparing the distribution system parameters with different penetration levels of solar PV system. The simulation results obtained demonstrate that high harmonic distortion level is injected correspondingly as the penetration capacity of PV system increased which indicates that the solar PV system should be integrating only up to a maximum possible capacity the network can carry. The integration of the PV system beyond this maximum penetration level causes production of high harmonic distortion which adversely affects the system performance. At the maximum penetration level which allows the acceptable harmonic distortion limit, the total voltage harmonic distortion and current demand distortion are found to be 4.97% and 14.98%, respectively.

INVESTIGATIONS OF TECHNOLOGICAL PARAMETERS IMPACT UPON QUALITY FORMATION IN SURFACE LAYER OF PARTS AT CENTRIFUGAL ROTARY PROCESSING

In the paper there are carried out investigations on the definition of the basic technological parameters impact of centrifugal-rotary processing in abrasive environment upon formation of surface layer quality in the parts worked. There is used a finite element method of deformation modeling in granulated massive rotating under the impact of centrifugal forces with the use of the (Comsol Multiphysics) packet. On the basis of computer the high-speed shooting processing and theoretical investigations of the process dynamics there are defined distributions of pressures and granule motion speed in the working chamber. A specified model of abrasive granule encounter with the surface worked at the centrifugal rotary processing on the basis of the modern researches and analysis with the use of the Ansys software. The dependences are obtained for the definition of the maximum penetration depth of environment particles into the surface of the part worked, metal removal, surface roughness which adequacy is confirmed by the results of experimental investigations. There is developed a specified procedure for the computation of roughness height parameters of the surface worked and machining capacity. A specified procedure for the computation of metal removal from the surface worked of parts is offered. An algorithm for the optimization of an engineering process is developed. The investigation results are introduced into production.