The development of an experimental technique to measure the influence of temperature on the mechanical properties of weldments

In large industries, such as in power stations, welds are widely employed to join different components together to meet various property requirements. The thermal gradient that develops during welding causes an inhomogeneous distribution of material properties, in areas adjacent to the weld, known as the Heat Affected Zones (HAZ). Welded joints subjected to elevated temperatures and loads during operations often experience a degradation of mechanical properties and performance of the joint. Studies have found that mechanical phenomena’s such as, fatigue and creep have compromised the structural integrity of weld zones. In essence a welded component acts as a composite material, for which it’s overall performance is dependent on its weakest material component. This study focuses on developing an experimental technique that is capable of measuring the influence of temperature on the mechanical and material properties across a weldment. The development of the experimental technique includes the design and optimisation of the hot zone of a welded tensile specimen, identification and characterisation of the different weld zones as well as, refining a strain recording strategy to detect the localised strains in each of the different weld zones. The application of the experimental technique is applied to welded components from turbine steam penetrations, which were extracted from a coal fired power station. The steam penetrations are a low Cr structural steel; (Cr 0.66, C 0.24 by wt. %) and have been in service for approximately 24 year (± 212 000 hrs). Two primary systems namely the Gleeble 3800 thermo-mechanical simulator and digital image correlation are used in this study. In order to accurately map the in-service evolution of material properties, each of the welds were mechanically loaded in tension and exposed to elevated operating temperatures. To induce mechanical loading at constant elevated temperatures, a Gleeble 3800 thermo-mechanical simulator with a tensile module was used to deform specimens at a strain rate of 50 µε.s1 . Experiments were conducted at various temperatures, ranging from room temperature (RT) to 535 o C. The evolution of material properties across the weldment was evaluated using Digital Image Correlation (DIC). DIC is a non-contact digital technique, capable of measuring localized strain during mechanical loading at elevated temperatures. In order to investigate the localized strain across the different weld zones, virtual strain gauges of one millimetre in length were simulated at intervals of one millimetre. It was found that there was a continuous accumulation of strain from the Fusion Line (FL) into the Parent Material (PM). This finding suggested that the HAZ nearest to the PM; which was the Fine Grained Heat Affected Zone (FGHAZ) was the weakest zone as it strained the most. The FL was found to be the least ductile region of the weld as most of the absorbed thermal energy provided during the welding process was used for strain hardening. At elevated temperatures, localised strain occurred at lower strain values than those at RT. This finding suggested that at elevated temperatures there was more thermal energy available for dislocation activation and mobilization. The influence of temperature on the local weld zones were evaluated by extending a specimen, containing just the parent material. A simulation of a virtual strain gauge across the monolithic specimen’s gauge length, revealed that necking occurred at the centre of the specimen which corresponded to the hot zone. In contrast, a simulation of virtual strain gauges across both welds revealed that necking occurred in the region between the HAZ and weld material. This finding inferred that the presence of a weld reduced the strength of the component, as the weld material was the weakest material. Furthermore, the in-service operating conditions was found to have significantly influenced the material behaviour of the welds. A weld that was exposed to a more elevated temperatures and loads, was found to have undergone a higher degree of material degradation, and strained to a larger extent when compared to a weld that was exposed to a more moderate operating environment

Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides

Here we systematically explore the use of pulsed laser deposition technique (PLD) to grow three basic oxides that have rocksalt structure but different chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable) and EuO (unstable). By tuning laser fluence, an epitaxial single-phase nickel oxide thin-film growth can be achieved in a wide range of temperatures from 10 to 750 {\deg}C. At the lowest growth temperature, the out-of-plane strain raises to 1.5%, which is five times bigger than that in a NiO film grown at 750 {\deg}C. MnO thin films that had long-range ordered were successfully deposited on the MgO substrates after appropriate tuning of deposition parameters. The growth of MnO phase was strongly influenced by substrate temperature and laser fluence. EuO films with satisfactory quality were deposited by PLD after oxygen availability had been minimized. Synthesis of EuO thin films at rather low growth temperature prevented thermally-driven lattice relaxation and allowed growth of strained films. Overall, PLD was a quick and reliable method to grow binary oxides with rocksalt structure in high quality that can satisfy requirements for applications and for basic research

Human Resource Practices and Organizational Performance in Pakistan: An Empirical Study on Pharmaceutical Industries

This research study intended to examine the relationship between HR practices and organizational performance of pharmaceutical industries of Pakistan. For this research, primary data were collected from 200 respondents from pharmaceutical industries of Pakistan using structure questionnaire sent to employees of different departments having different job status, asked the questions about training, payroll for performance, participation in decision making, organization commitment and organizational performance. The correlation and regression analysis is used in this paper to measure the impact of HR practices on organizational performance. The correlation results shows significant relationship between the HR practices and organizational performance and Regression results shows that independent variables significantly affect the dependent variable. It is found that human resource practices enhance the pharmaceutical industries of Pakistan. I also found, by increasing the practices of training, payroll performance, participation in decision making and organization commitment raised the organizational performance.  In order to ensure the organizational performance, the pharmaceutical industries may pay special focus and attention to these four HR practices. Key Words: Human Resource Practices, training, participation in decision making, organization commitment, payroll for performance and organizational performance

Use of integrated clinical scenarios in neuroanatomy laboratory sessions a strategy to foster students’ learning

Objective: Combinations of various teaching strategies have been employed to enhance neuroanatomy teaching, to little success. Herein, we describe the use of integrated clinical scenarios in anatomy laboratory sessions as an educational strategy to improve the learning process for students undertaking neuroscience course. Methods: We assessed the perception and performance of students who utilised the integrated clinical resources in the neuroanatomy labs. We also compared the performance of the students on their neuroscience course with the performance of the previous year\u27s students (who did not use the clinical scenarios). Results: A total of (130) 88% of the registered student both male and female participated by filling out a questionnaire. A majority (80%) of students supported introducing clinical cases at this early stage and agreed that cases covered learning objectives well. Students (81%) preferred a decreased faculty participation and 68% strongly agreed that cases were well integrated with other disciplines and assisted critical thinking and conceptual understanding. Most of them (90%) approved using plastic models and pictures as resource-material. The average mark obtained for all block together between the two cohorts did not differ significantly, while student performance was significantly improved in neuroscience block of the cohort which had access to the integrated clinical scenarios. Conclusions: Collectively, or specifically designed neuroanatomy lab sessions provided students with an empowering experience to help them apply critical thinking and use their basic neuroscience knowledge to solve clinical problems

Sperm PLCζ: From structure to Ca2+ oscillations, egg activation and therapeutic potential

AbstractSignificant evidence now supports the assertion that cytosolic calcium oscillations during fertilization in mammalian eggs are mediated by a testis-specific phospholipase C (PLC), termed PLC-zeta (PLCζ) that is released into the egg following gamete fusion. Herein, we describe the current paradigm of PLCζ in this fundamental biological process, summarizing recent important advances in our knowledge of the biochemical and physiological properties of this enzyme. We describe the data suggesting that PLCζ has distinct features amongst PLCs enabling the hydrolysis of its substrate, phosphatidylinositol 4,5-bisphosphate (PIP2) at low Ca2+ levels. PLCζ appears to be unique in its ability to target PIP2 that is present on intracellular vesicles. We also discuss evidence that PLCζ may be a significant factor in human fertility with potential therapeutic capacity