Numerical analysis of convergent-divergent nozzle using finite element method

In this paper, Finite element method (FEM) were used to simulate the different flow configuration. Convergent divergent (CD) nozzle was considered with extended divergent duct. 1 mm of micro jets orifice diameter were arranged at ninety degrees at PCD 13 mm to control base pressure in a suddenly expanded flow. The designed Mach number of CD nozzle is 1.87 and area ratio 3.24 was considered. The different L/D of the duct was used from 2 to 10. The nozzle pressure simulated for 3, 5, 7, 9 and 11. In this case. Two-dimensional planar model was designed using ANSYS fluent analysis. The total wall pressure distribution and Mach number from inlet to the outlet was observed. From the results, it is detected that the micro jets control the loss of pressure and decreases the drag at the suddenly expanded region. The results also show, we can fix the flow parameter which will result in the maximum gain in the base pressure and velocity. In present study, the CD nozzle designed and modelled using available ANSYS fluent database: K-ε standard wall function turbulence model has been used and validated with the commercial computational fluid dynamics (CFD

A new approach to low-cost open-typed subsonic compressible flow wind tunnel for academic purpose

The most challenging task concerning wind tunnel description is, to ascertain the supporting mechanism at high-speed flows inside test section with least complexity and low-cost. This paper presents the design and development of a simple and cost effective test section for a subsonic compressible wind tunnel for educational purpose. The objective of this open-type wind tunnel was to demonstrate flow around model without any interference at high speeds. In this work, that is study of flow analysis, a subsonic square nozzle was fabricated to achieve maximum velocity of 340 m/s. The test section is 25 mm x 25 mm x 70 mm and is externally attached with travers. It starts from length 25 mm to avoid dead zone and ends at 95 mm to avoid end effects, and on one of the surfaces pressure taps were provided for measuring pressure at different locations inside the wall of duct. The duct length was taken as 100 mm and the pressure taps were at the distance of 8 mm, 16 mm, 24 mm, 49 mm, 59 mm, 80 mm and 90 mm to measure wall pressure. They were connected to sensors through PVC tubes and further to DAQ using LabVIEW interface, and finally to the computer. In addition to this, the flow through the duct can be visualized using transparent glass to find the reattachment point for our re-circulation bubble. A new concept of attaching models in a 3 D traverse was found very easy for inserting it from behind in test section, and thereby interference and breaking of strings was eliminated. Calibration was done through pitot tube at the exit of test section in y and z direction. The nature of graph tells about the correctness of the designed wind tunnel test section. After calibration, we found that the exit velocity is constant for approximately 80 percent area. This area is the effective test section work area

Transferrin-bearing polypropylenimine dendrimer for targeted gene delivery to the brain

The possibility of using genes as medicines to treat brain diseases is currently limited by the lack of safe and efficacious delivery systems able to cross the blood-brain barrier, thus resulting in a failure to reach the brain after intravenous administration. On the basis that iron can effectively reach the brain by using transferrin receptors for crossing the blood-brain barrier, we propose to investigate if a transferrin-bearing generation 3-polypropylenimine dendrimer would allow the transport of plasmid DNA to the brain after intravenous administration. In vitro, the conjugation of transferrin to the polypropylenimine dendrimer increased the DNA uptake by bEnd.3 murine brain endothelioma cells overexpressing transferrin receptors, by about 1.4-fold and 2.3-fold compared to that observed with the non-targeted dendriplex and naked DNA. This DNA uptake appeared to be optimal following 2h incubation with the treatment. In vivo, the intravenous injection of transferrin-bearing dendriplex more than doubled the gene expression in the brain compared to the unmodified dendriplex, while decreasing the non-specific gene expression in the lung. Gene expression was at least 3-fold higher in the brain than in any tested peripheral organs and was at its highest 24h following the injection of the treatments. These results suggest that transferrin-bearing polypropylenimine dendrimer is a highly promising gene delivery system to the brain

Vertical relationships between the divergence angle of maxillary molar roots and the maxillary sinus floor: A cone-beam computed tomography (CBCT) study

Aim: To assess the relations between the divergence angle of the maxillary molar roots and their proximity to the maxillary sinus floor using CBCT. Method: This study comprised CBCT scans of the maxilla, including at least the inferior one-third of the maxillary sinus and at least one molar present in any quadrant with complete eruption and root formation. Evaluation included the vertical relations between the maxillary molar root apices and the maxillary sinus floor (MSF), and the root divergence was measured from the root apices to the floor of the pulp chamber. The chi-square test was used for the associations between the study parameters. For the correlation between root divergence angles and MSF vertical relationship types, the Spearman test was used. A P-value 45⁰ angle groups, and a higher prevalence of the Type I relationship was found in the 21-45⁰ angle group. For the distobuccal-palatal angle groups, higher percentages of the MSF Type II relationship were found in the three angle groups. For all teeth, there was a significant positive correlation between the MSF vertical relationship and the mesiobuccal-palatal angle (r = 0.116; P = 0.039). Conclusion: There was a positive correlation between the divergence angle of the roots and their vertical relationship with the MSF. Clinicians should assess the divergence between the roots before performing extraction or endodontic treatments

Biocompatibility and Antioxidant Activity of a Novel Carrageenan Based Injectable Hydrogel Scaffold Incorporated with Cissus Quadrangularis for Facilitating Dentin-Pulp Complex Regeneration – An in vitro Study

Abstract Background: Over the past years, polysaccharide based scaffolds has been the most promising material for tissue engineering. In the present study, carrageenan, an injectable scaffold has been used owing to its advantage and superior property. Cissus quadrangularis, a natural agent was incorporated into the carrageenan scaffold which probably has the potential to make a favourable micro-environment for the dentin-pulp regeneration. Therefore, the present study aimed to assess the antioxidant activity and biocompatibility of the material. Methods: The present in vitro study comprised of four study group each constituting a sample of 15 (n=15). The carrageenan hydrogel without addition of Cissus quadrangularis acted as control group (Group-I). Based on the concentration of aqueous extract of Cissus quadrangularis (10% w/v, 20% w/v and 30% w/v) in carrageenan hydrogel, respective study groups namely II, III and IV were considered. Antioxidant activity was assed using 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay and biocompatibility test was performed by using brine shrimp lethality assay. One-way ANOVA with the post hoc tukey test was performed using SPSS software v22. Results: Significant difference (P&lt;0.05) in the antioxidant activity was observed among the study groups with 20% w/v Cissus quadrangularis hydrogel (group III) reported the highest and control group showed the least antioxidant activity. A significant (P&lt;0.01) drop in the antioxidant activity was observed in group IV when compared with group III. A significant (P&lt;0.001) dose-dependent increase in biocompatibility was observed. Scanning electron microscopy analysis was performed to assess the surface morphology with different concentration of cissus quadrangularis, wherein group III showed even distribution throughout the hydrogel although the particles are close and densely arranged. Reduced antioxidant activity in group IV was probably due to clumping of the particles, thus reducing the active surface area.Conclusion: Keeping the limitations of the in vitro study, it can be assumed that carrageenan based injectable hydrogel scaffold, incorporated with 20% w/v Cissus quadrangularis can provide favourable micro-environment as it is biocompatible and possess better antioxidant property. Hence, this study lays ground for future studies to explore this scaffold incorporated with Cissus quadrangularis for dentin pulp regeneration.</jats:p