Effect of corner radii on the thermal & fluid flow performance of the laminar flow through rectangular micro channel

Metallic micro channels have the advantage of high thermal conductivity to strength ratio. The recent advances in the manufacturing processes, has increased the feasibility of realizing metallic micro channels with close dimensional control. Presently, various types of micro manufacturing processes are available for the realization of the metallic micro channels. However it is not practical to manufacture any dimensional feature with sharp corner. Depending on the choice of the manufacturing process, the corners get rounded to varying degree. When compared with the dimensions of micro channels the magnitude of the corner radius is considerable. In this paper an attempt has been made to study numerically the effect of corner radius on the performance of the micro channels. Commercially available computational fluid dynamics software ANSYS CFX was used for the simulation of micro channels performance. The thermal & fluid flow performance of the micro channel was simulated by varying the corner radius from 50 microns to 200 microns. The coolant flow velocities were varied from 0.48m/s to 1.27m/s. The Temperature dependent material properties have been used in the analysis. The simulation results were validated using published literature

Experimental & numerical study of forced convection laminar flow through copper micro channel heat sink

A rectangular micro channels having 500 microns width & 1500 microns depth have been machined out of Oxygen free high conductivity Copper material on an area of 12.5mm X25mm. De-ionized water was used as a coolant. The thermal & fluid flow performances have been tested for the flow velocities ranging from 0.5m/s to 1.2m/s. Micro channels performances have been numerically simulated using commercially available computational fluid dynamics software ANSYS CFX. The simulated results have been validated with the experimental results and published literature . The effects of Temperature dependent material properties on simulation have been examine

A novel sensor for detection of oil condition and contamination based on a thermal approach

Oil condition and contamination can be a major issue in lubrication systems such as aircraft, automobiles etc. Lubricating or cooling oil contamination occurs when metallic or non-metallic particles are produced due to wear of machine components and these are not captured by the filter system. Furthermore, thermal stressing causes oxidation and thereby degradation of the oil. Liquid contamination can occur from water condensation or fuel from heat exchangers. These can cause degradation of the oil and reduce the lubricating properties and clogg oil paths and accelerate the wear of moving parts. On-line oil condition monitoring systems are important for preventive maintenance especially for aircraft engine bearings, aviation gearboxes etc. Current on-line oil condition monitoring sensors are mainly eddy current, optical based. These sensors have a major drawback that they are prone to surface contamination and non-linearity. The gauges are also not sensitive enough to detect extremely small particulates or are prone to false detection such as trapped bubbles. A new sensor has been developed using thin film heat transfer sensors that can detect any form of contamination in oil such as metal, nonmetals, oxidation, liquids etc. The sensor works on the principle of measuring the thermal product of the material, as the composition of the material in contact with the sensor changes the thermal product changes and can be detected. The sensor can be used for both on-line and in-line condition monitoring and has been demonstrated to be robust. Initially, lab based tests were carried out to optimise the system for sensitivity and signal to noise ratio. The sensor has been demonstrated to detect 0:25% of contaminants by mass. Experiments were carried out by seeding metallic and non-metallic particles of various sizes to an engine oil system to validate its performance.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Hydrophobic interaction of 2-trifluoromethyl-N 10-substituted phenoxazines with bovine serum albumin and reversal of drug resistance in bacterial cells

Objective: The objective of this study was to report the hydrophobic interaction of 2-trifluoromethyl-N10 Methods: Binding of six compounds, 10-3-substituted phenoxazines with bovine serum albumin and reversal of drug resistance in bacterial cells. '-N-morpholinopropyl-2-trifluoromethyl phenoxazine (1C), 10-4'-N-morpholinobutyl-2-trifluoromethyl phenoxazine (2C), 10-3'-N-pyrrolidinopropyl-2-trifluoromethyl phenoxazine (3C), 10-4'-N-pyrrolidinobutyl-2-trifluoromethyl phenoxazine (4C), 10-N-piperidinoacetyl-2-trifluoromethyl phenoxazine (5C), and 10-N-pyrrolidinoacetyl-2-trifluoromethyl phenoxazine (6C), to bovine serum albumin (BSA) has been measured by gel filtration and equilibrium dialysis methods. The binding of these compounds to BSA has been characterized by percentage of bound drug (β), the association constant (K), the apparent binding constant (k) and free energy (�Fo Results: The results of displacing experiments reveal that the phenoxazine benzene rings and tertiary amines attached to the side chain of phenoxazine moiety are bound to a hydrophobic region on the albumin molecule. Among the compounds examined the butyl series seems to possess better reversing ability, suggesting that the activity could be related to lipophilicity and the extent of binding to BSA.). The binding of phenoxazine derivatives to BSA, a serum protein that binds and transports small molecules, is correlated with their partition coefficients. Further, the ability of the phenoxazines (1C-6C) on the antibacterial activity of five antibiotics, kanamycin, spectinomycin, gentamycin, streptomycin and benzylpenicillin was examined for their ability to reverse the resistance of E. coli K12 MG 1655 and E. coli ST 58. Conclusions: Phenoxazines are bound to albumin by hydrophobic interactions of their benzene rings. The alkyl side chain, particularly butyl chain of phenoxazines intensifies the interaction of phenoxazines with BSA. The compound that binds to a greater extent with protein possesses more activity for reversing of drug resistance. © 2015, International Journal of Pharmacy and Pharmaceutical Science. All right resurved

Cloud cavitation vortex shedding inside an injector nozzle

The development and collapse of cloud cavitation and its link to surface erosion within a transparent test single-orifice nozzle operating with a closed Diesel fuel hydraulic circuit, has been characterized using high-speed imaging. Data have been obtained for a range of cavitation and Reynolds numbers under fixed lift positions. Post processing of a large number of images acquired with short exposure time (1 μs) allowed the elucidation of the distinct flow phenomena associated with the highly transient two-phase flow. At the inlet of the flow orifice, the vapour cloud was found to occupy the largest part of the nozzle hole cross-section. Coherent vortical structures of a hairpin shape have been detected to onset at the closure region of this vapour cloud and shed downstream in a fully transient manner. The effect of the operating parameters on the temporal and spatial characteristics with regards to the emergence and collapse of the hairpin vortices has been quantified. It has been established that the cavitation-vortex shedding was taking place in a periodical manner, characterized by a Strouhal number

Impact of Biological Sex on Immune Activation and Frequency of the Latent HIV Reservoir during Suppressive Antiretroviral Therapy

Background: Persistent HIV infection of long-lived resting CD4 T cells, despite antiretroviral therapy (ART), remains a barrier to HIV cure. Women have a more robust type 1 interferon response during HIV infection relative to men, contributing to lower initial plasma viremia. As lower viremia during acute infection is associated with reduced frequency of latent HIV infection, we hypothesized that women on ART would have a lower frequency of latent HIV compared to men. Methods: ART-suppressed, HIV seropositive women (n = 22) were matched 1:1 to 22 of 39 ART-suppressed men. We also compared the 22 women to all 39 men, adjusting for age and race as covariates. We measured the frequency of latent HIV using the quantitative viral outgrowth assay, the intact proviral DNA assay, and total HIV gag DNA. We also performed activation/exhaustion immunophenotyping on peripheral blood mononuclear cells and quantified interferon-stimulated gene (ISG) expression in CD4 T cells. Results: We did not observe evident sex differences in the frequency of persistent HIV in resting CD4 T cells. Immunophenotyping and CD4 T-cell ISG expression analysis revealed marginal differences across the sexes. Conclusions: Differences in HIV reservoir frequency and immune activation appear to be small across sexes during long-term suppressive therapy