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ABSTRACTDisplaced enhancement devices are inserts positioned inside pipes that increase the heat transfer rate. This study presents an original application of an inverse analysis technique to experimental infrared temperature data to estimate the local convective heat flux for forced convection flow in a pipe in which this kind of device is present. Butterfly-shaped inserts have been investigated to determine their local and global thermal performance. The insert produces a distortion in the velocity profile that causes an irregular distribution of the wall heat flux along the circumferential coordinate. Several studies have investigated displaced enhancement devices, but they generally considered only the overall heat transfer performance. The present work aims to fill this gap by presenting and testing an experimental procedure for estimating the local convective heat flux in pipes equipped with this type of insert. The experimental results obtained in the present investigation are useful for the design of heat exchangers for processes in which product temperature must be carefully controlled (e.g. pharmaceutical and food industries). These types of devices induce significant spatial variation of the heat flux, and quantitative data of this aspect is of primary importance.

This paper presents and assesses an inverse heat conduction problem (IHCP) solution procedure which was developed to determine the local convective heat transfer coefficient along the circumferential coordinate at the inner wall of a coiled pipe by applying the filtering technique approach to infrared temperature maps acquired on the outer tube’s wall. The data−processing procedure filters out the unwanted noise from the raw temperature data to enable the direct calculation of its Laplacian which is embedded in the formulation of the inverse heat conduction problem. The presented technique is experimentally verified using data that were acquired in the laminar flow regime that is frequently found in coiled−tube heat−exchanger applications. The estimated convective heat transfer coefficient distributions are substantially consistent with the available numerical results in the scientific literature.

AbstractThe present study was carried out to examine the use of zebrafish (Danio rerio) as a preliminary screening model for testing the effect of potential immunostimulant substances on the innate immune system. β-Glucan, a polysaccharide used widely as an immunostimulant, was used as a representative molecule and tested on zebrafish embryos and larvae. The efficacy of the molecule was evaluated by determining the differential expression of some selected genes related to the immune system by RT-qPCR. Larvae from 72 hours post fertilization were found at the optimal developmental stage for assessing the expression of the selected genes.To verify if the β-glucan entered the larvae and therefore was responsible for the effects produced, the molecule was labeled fluorescently to check its localization by using microscopy. For estimating the effects of β-glucan on gene expression, zebrafish embryos and larvae were immersed in three different concentrations of β-glucan (50, 100, and 150 μg/mL) using five different exposure times. A stronger gene induction was observed when longer times of exposure and older larvae were used. The most evident effects of β-glucan were the overexpression of the genes TNFα, MPO, TRF,and LYZ.Moreover, slight changes in MPOexpression were detected using a transgenic line of zebrafish (MPO::GFP), and a temporal increase in resistance against Vibrio anguillarumwas found after β-glucan immersion. The assay used in this study permits the testing potential of immunostimulants in a simple and cost-effective way.

Thermotolerant Saccharomyces strains were crossed with mesophilic Saccharomyces cerevisiae and with cryotolerant Saccharomyces bayanus. The former hybrid is fertile confirming thermotolerant strains as S. cerevisiae. The spores from this hybrid, though, possess a low germinability and give cultures that grow poorly. The hybrid cryotolerant x thermotolerant is sterile and show a new combination of the parental strains' traits improving their technological application. © Rapid Science Ltd. 1998