Experimental Analysis of Friction Stir Welding of Dissimilar Alloys AA6061 and Mg AZ31 Using Circular Butt Joint Geometry

AbstractThe Aluminium alloy 6061 and Magnesium alloy AZ31 plates of 6mm thickness are welded in circular butt joint geometry by friction stir welding (FSW) process, using CNC vertical milling machine. Process parameters such as welding speed and tool rotational speed play an important role to obtain a better weld joint for dissimilar metals/materials. The friction stir welding tool is one of the critical components to the success of this process. It consists of a cylindrical shoulder and a pin with different geometry. In the experimental work, the said tool has been designed with cylindrical pin having four different geometries for friction stir welding of the dissimilar circular metal plates. Friction stir welding has been carried out at welding speed varying from 10 to 40mm/min and tool rotational speed from 800 to 2000rpm. Effects of process parameters on butt welded circular joint were investigated for weld strength. In this research work, it is found that welded joint between dissimilar metals alloys Al 6061 and Mg AZ31 can be formed using friction stir welding by selecting proper tool pin profile and welding parameters. It is suggested that friction stir welding of Aluminium alloy and Magnesium alloy with circular butt joint geometry would be useful in the future for automobile applications by getting the benefits from each material in a functional way

Stability and compatibility of topotecan hydrochloride for injection with common infusion solutions and containers

Abstract The stability and compatibility of topotecan hydrochloride with common infusion solutions and containers were studied. During this study, the leaching of diethylhexyl phthalate (DEHP), a major plasticizer of some polyvinyl chloride (PVC) materials was also investigated. A formulation of topotecan hydrochloride was added to 50 ml PVC infusion bags, polyolefin infusion bags and 150 ml glass bottles containing either 5% dextrose injection or 0.9% sodium chloride injection at an initial nominal topotecan concentration of 0.05 mg ml − 1 . Additionally, the topotecan hydrochloride formulation was added to 50 ml PVC infusion bags containing either 5% dextrose injection or 0.9% sodium chloride injection at an initial nominal topotecan concentration of 0.025 mg ml − 1 . Containers were maintained at 5°C for 7 days or 23 -24°C for 24 h. Samples were analyzed using a stability-indicating HPLC method to determine the concentration of topotecan and the presence of any degradates. The samples were also analyzed by separate HPLC methods to detect the presence of DEHP and the hydrolyzed lactone ring form (SKF 105992) of topotecan hydrochloride. In addition, the pH of each sample was measured initially and at the end of the storage time. There was no significant loss of topotecan observed for any of the conditions studied and no significant increase in degradates was observed. The pH remained unchanged for all samples between the start and end of the study. At the concentrations studied, topotecan hydrochloride was stable for up to 24 h at room temperature and for up to 7 days at 5°C, in PVC and polyolefin infusion bags and glass bottles containing either 5% dextrose injection or 0.9% sodium chloride injection. The presence of topotecan hydrochloride did not contribute to leaching of DEHP in the PVC infusion bags. © 1997 Elsevier Science B.V

Transmission phenotype of mycobacterium tuberculosis strains is mechanistically linked to induction of distinct pulmonary pathology

In a study of household contacts (HHC), households were categorized into High (HT) and Low (LT) transmission groups based on the proportion of HHC with a positive tuberculin skin test. The Mycobacterium tuberculosis (Mtb) strains from HT and LT index cases of the households were designated Mtb-HT and Mtb-LT, respectively. We found that C3HeB/FeJ mice infected with Mtb-LT strains exhibited significantly higher bacterial burden compared to Mtb-HT strains and also developed diffused inflammatory lung pathology. In stark contrast, a significant number of mice infected with Mtb-HT strains developed caseating granulomas, a lesion type with high potential to cavitate. None of the Mtb-HT infected animals developed diffused inflammatory lung pathology. A link was observed between increased in vitro replication of Mtb-LT strains and their ability to induce significantly high lipid droplet formation in macrophages. These results support that distinct early interactions of Mtb-HT and Mtb-LT strains with macrophages and subsequent differential trajectories in pathological disease may be the mechanism underlying their transmission potential.publishersversionpublishe

Preexisting helminth infection induces inhibition of innate pulmonary anti-tuberculosis defense by engaging the IL-4 receptor pathway

Preexisting helminth infection impairs immunity against subsequent M. tuberculosis infection, in part by inducing alternatively activated macrophages

The process of Internationalization in Small and Medium Enterprises (SMEs) : "Challenges encountered in the process of Internationalization from product adaptation and standardization perspective"

This dissertation focuses on the challenges that arise when the SMEs enter into an international market (Internationalization) and adopting international product strategy to survive in foreign market. To be able to gain better understanding of the subject, research questions concerning the challenges faced during internationalization by SMEs from product adaptation and standardization perspective. Challenges in internationalization have been categorized into internal and external challenges. Internal challenges deals with firm specific while external challenges arise from country and industry specific factors. At the same time international product strategy counting product adaptation and standardization has been discussed. The empirical data includes case study of one Swedish company manufacturing assistive listening devices (hearing equipment for hearing impaired people) situated in Halmstad, Sweden. Findings shows that the main challenges in internationalization are socio cultural differences and inadequate knowledge about the foreign market while laws and regulations regarding frequency standards issues are most challenging in international product strategy

Evidence that phosphate specific transporter is amplified in a fluoroquinolone resistant Mycobacterium smegmatis

We reported in an earlier study that active efflux of drug has a predominant role in conferring resistance in a laboratory-generated ciprofloxacin-resistant mutant of Mycobacterium smegmatis. This mutant exhibited mRNA level overexpression, as well as chromosomal amplification, of the gene pstB, encoding the putative ATPase subunit of phosphate specific transport (Pst) system. We demonstrate here that this mutant shows enhanced phosphate uptake and that inactivation of pstB in the parental strain results in loss of high affinity phosphate uptake and hypersensitivity to fluoroquinolones. These findings suggest a novel role of the Pst system in active efflux, in addition to its involvement in phosphate transport