In this paper, numerical 3D simulation of viscoelastic developing flow in a rectangular duct with the nonlinear constitutive equation was considered.So far, researchers have focused on the fully developed zone. In these cases, the effects of entrance region of flow and changes in important quantities of developing flow were neglected. Therefore three-dimensional modeling of the entrance region is an innovation of this work. For modeling the stress term, PTT constitutive equation which is one of the most perfect models was used. It should be noted that, the Oldroyd conditions was ingratiated and secondary flow has been simulated.Considering three-dimensionality of the solution domain as well as the dependency and nonlinearity of equations, artificial compressibility explicit method and staggered grid for solving the equations is purposed.The result is in good agreement with the others reported in the fully developed region.

Introduction: Use of an adhesive with a suitable composite resin is an important factor in tooth-colored restorations and increasing marginal sealing ability. The aim of this study was to evaluate the microleakage of various adhesives with composite resins using FLUID filtration and dye extraction techniques and assessment of the correlation between these two techniques.Materials and Methods: In this in vitro study, class II cavities were prepared on the proximal surfaces of 48 extracted sound human premolar teeth, measuring 1.5±0.5 mm in gingival width, 4 mm in occluso-gingival height and 1.3 of the inter-cuspal distance in width. The samples were divided into four groups (n=12). Group 1; OptiBond Solo Plus adhesive/Herculite XRV composite resin; Group 2: OptiBond Solo Plus adhesive/Master Dent composite resin; Group 3: Prime & Bond NT adhesive/Herculite XRV composite resin; Group 4: Prime & Bond NT adhesive/Master Dent composite resin. Microleakage was assessed primarily by FLUID filtration and then by dye extraction techniques. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction and Spearman's rho correlation test at 95% confidence interval.Results: The minimum and maximum mean microleakage values were recorded in FLUID filtration and dye extraction techniques groups 1 and 4, respectively. There were significant differences between the experimental groups in microleakage with the two methods of leakage assessment (p value=0.001). Spearman's rho revealed a strongly direct correlation between the two methods (r=0.797, p value=0.000).Conclusion: In both methods of microleakage assessment, use of ethanol-based in comparison to acetone-based adhesive resulted in microleakage reduction. Application of light-cured composite resin contrary to self-cured composite resin with both types of adhesives increased marginal sealing ability.

Introduction: MTA Fillapex and iRoot SP are two new sealers which have very similar characters to MTA. The purpose of this study was to assess and compare apical seal of the obturated canals with the iRoot SP, MTA Fillapex and AH-Plus sealers.Materials & Methods: Seventy two freshly extracted single root canal human premolars were selected for this study. The canals were instrumented with hand files using step back technique. Six specimens were assigned for positive control and six for negative control groups. The rest of the specimens were randomly divided into three groups of 20 and obturated with gutta percha and one of the aforementioned sealers. Microleakage in all groups was assessed, 2 weeks and 3 months after obturation of canals, by means of FLUID filtration. The data were analyzed using repeated measurement and post-hoc Tukey test. The level of significance was set at P<0.05.Result: In none of the assessment intervals, there was a significant difference between AH-plus and MTA Fillapex. iRoot SP had less microleakage compared to other groups significantly (P<0.001). Microleakage assessments revealed no significant differences between 2 weeks and three months in all groups.Conclusion: iRoot SP sealer had significantly less microleakage compared to MTA Fillapex and AH-Plus.

BACKGROUND: Treatment of hemorrhagic shock is the major problem in emergency surgery. FLUID therapy is one of the first steps but, the conflict has been over the temperature used for the FLUID injected to the patient. The aim of this study was to determine the effect of FLUID temperature in intravenous FLUID resuscitation of hemorrhagic shock. METHODS: In this experimental study, 3 groups of 10 rabbits underwent  emorrhagic shock class III (mean arterial pressure = 40 mmHg) by catheter on femoral artery. Within 25 minutes, ringer lactate solutes with controlled temperatures of 15°C, 25°C and 37°C were injected through femoral venous line. They were followed for 72 hours. RESULTS: In the lowest, middle and the highest FLUID temperature group, mortality rate was 90%, 10% and 40%, respectively. Statistically significant difference was seen between the 15°C and 25°C resuscitation groups (P<0.001). CONCLUSIONS: Our findings showed possible benefit of room temperature as the optimal FLUID temperature for FLUID resuscitation in hemorrhagic shock.

Viscoelastic FLUID hammer is a type of FLUID hammer in which a viscoelastic non-Newtonian FLUID flows in a pipeline. In this study, the FLUID-structure interaction in this phenomenon is investigated. The governing equations are viscoelastic FLUID and structure equations which are coupled together. Viscoelastic FLUID equations consist of continuity and momentum which govern the transitional flow in the pipes. Oldroyd-B model is used as the constitutive equation. This model is suitable for dilute viscoelastic solutions and Boger liquids. Structural equations include pipe axial velocity and stress equations. A two-step variant of the Lax-Friedrichs method is used to simulate FLUID-structure interaction in a reservoir-pipe-valve system. A viscoelastic FLUID polymer is selected and the behavior of the polymer pressure head and shear stresses during FLUID hammer is investigated. Three types of couplings were examined. Junction, Poisson, and the combination of two aforementioned couplings called junction and Poisson coupling. The effects of these couplings for the FLUID are modeled in three states. ideally, Newtonian and viscoelastic. The FLUID viscosity in Newtonian and viscoelastic states is considered the same. The results of the study show that the imposed shear stresses with viscoelastic FLUID are significantly lower than those in the Newtonian state. Comparing coupling effects during FLUID hammer is found that the lowest shear stresses are assigned to Poisson coupling.