Transport, magnetic and structural properties of(Tl0.5Pb0.5)Sr2-xCexCa2Cu3Oy compounds

Resistivity, DC magnetization and X-ray diffraction measurements were performed on 6 sample with nominal composition (Tl0.5Pb 0.5)Sr2-xCexCa2Cu3 Oy, with x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5. As cerium content was increased, the transition temperature increased up to about 6 K when x=0.1. The phase diagram of the onset transition temperature versus Ce content reflects the expected behavior as the hole concentration in the Cu-O planes is expected to decrease with increasing x, passing from overdoped through optimally doped to an underdoped state for higher values of Ce4+ replacing Sr2+ atoms. Magnetization measurements at 4 K, in cyclic field 9 Tesla, on the other hand, showed that the critical current density of the samples decreased as Ce content was increased for all values x. It also showed the existence of the superconducting phase up to x=0.5, which was not detectable by resistivity measurements. X-ray diffraction measurements, indicate that Ce enters the structure of the Tl-1223 phase, and hence affect its superconducting properties as it changes the charge carrier concentration in the Cu-O plane

Effect of La3+ substitution for Sr2+ on thephase formation, structure and properties of (Tl0.5Pb0.5)Sr2Ca2Cu3Oy compounds

Optimization of the hole concentration in (Tl0.5Pb0.5)Sr2Ca2Cu3 Oy (Tl-1223) was attempted though partial replacement of Sr2+ by La3+. Nine samples with nominal composition (Tl0.5Pb0.5)Sr2-xLax Ca2Cu3Oy were prepared, with x varies from 0 to 2. Magnetization measurements as a function of temperature showed that the transition temperature increased with increasing La content. These measurements also showed an increase of the diamagnetic signal as La was increased. X-ray diffraction patterns of the samples showed that La addition improved the phase purity of Tl-1223 for low level La substitution (x0.03). Formation of impurity phases and a phase transformation were also observed for high La contents. The microstructure appearance of the samples with different La content was different. Samples with x values 0.5, 1 and 2, were very brittle and the pellets dissociated into fine powder in one week time. These results will be discussed in terms of changes in the charge carrier concentration in the Cu-O planes of the originally overdoped Tl-1223 high temperature superconductor

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Soft X-ray photoemission studies of Hf oxidation

Soft X-Ray Photoemission Spectroscopy using surface sensitive Synchrotron Radiation has been applied to accurately determine the binding energy shifts and the valance band offset of the HfO2 grown on Hf metal. Charging of oxide films under x-rays (or other irradiation) is circumvented by controlled and sequential in-situ oxidation. Photoemission results show the presence of metallic Hf (from the substrate) with the 4f7/2 binding energy of 14.22 eV, fully oxidized Hf (from HfO2) with the 4f7/2 binding energy of 18.16 eV, and at least one clear suboxide peak. The position of the valence band of HfO2 with respect to the Hf(m) Fermi level is determined as 4.05 eV

Dynamic property analysis and development of composite concrete floor (CCF) and vibration serviceability : a review

This review article concerns floor vibration, describes the nature of floor vibration and provides options for avoiding it through design, or in the case of existing buildings, reducing or eliminating it through alterations. Excessive floor vibration has become a greater problem as new rhythmic activities, such as aerobics, generators, air conditioners and long-span floor structures have become more common. The current push towards stronger concrete materials and the use of prestressing is resulting in increasing fineness and dynamism of long-span concrete floors in buildings. Although concrete floors have a good vibration serviceability track record, this trend may lead to an increasing number of floors failing their vibration serviceability. There is a current trend towards ever more slender concrete floor structures, which is resulting in more frequent problems with their vibration serviceability. Predictive methods for vibration serviceability must consider not only the structures themselves, but also the non-structural elements which are attached to them, as these may have a significant effect on the dynamic characteristics of the floor structural system. As there has been very little past research in this area, this article describes an investigation into the effects of raised access floors on the vibration serviceability of long-span concrete floors

Magnetic properties of fluorinated Pb-doped Hg-1223 high Tc superconductors

Fluorination of Pb-doped HgBa2Ca2Cu3Oy (Hg-1223) system was investigated. Structural and magnetic measurements reveal that fluorine addition promotes the phase formation, optimize the charge carrier concentration, and enhance flux pinning. We report an increase in both the transition temperature and the critical current density through controlled fluorine incorporation. Even a possible change in the pinning mechanism in this technologically important system is suggested

High resolution XPS study of oxide layers grown on Ge substrates

High resolution X-ray Photoelectron Spectroscopy (XPS) was used to analyze thin layers of germanium oxide grown on germanium substrates under various conditions. The results reveal the presence of high density of electron states located at the oxide/germanium interface that lead to the energy band bending. The surface of native oxide layers and that of thin oxide layer grown under dry oxygen correspond to GeO2 composition. Under Ar etching, lower oxidation states were revealed. Short in-situ heat treatment at T=400 degrees C under ultra high vacuum leads to the removal of the oxide layer. In addition, the analysis of the layer grown at T=380 degrees C under dry oxygen suggest that carbides form at the oxide/substrate interface

A study of stability of tungstophosphoric acid, H{sub 3}PW{sub 12}O{sub 40}, using synchrotron XPS, XANES, Hexane cracking, XRD and IR spectroscopy

Tungstophosphoric Acid (HPW) has been investigated using different spectroscopic and chemical techniques. Bulk sensitive techniques such as x-ray diffract ion (XRD) and infrared (IR) spectroscopy indicate that the acid is stable at temperatures as high as 300 degrees C or higher. However, our work suggests that HPW starts loosing stability at temperature as low as 200 degrees C. For instance, P 2p peak was not detected in the XPS spectrum of HPW preheated at 100 degrees C, but was clearly observed after preheating the acid at 200 degrees C and 400 degrees C. This suggests the destruction of the molecules of the surface leading to the enrichment of surface with phosphorus. These results may explain why HPW deactivates very fast, e.g., 8 min at 200 degrees C, in hexane cracking experiments. This could limit the use of HPW in surface reactions that even require moderate temperatures. Detailed infrared spectroscopic investigation of the HPW as a function of temperature showed a gradual in crease in absorbance of the W-O-W corner shared vibration relative to the absorbance of the other bands. This indicates that the symmetry, and hence the stability, of the molecule was decreased upon heating

Identifying the Level of Awareness on Value Management Practice amongst Construction Developers

Construction Industry is one of the catalysts that enable such a nation economy to kept runs and grow from time to time. In this large and unique industry, the position of Architect, Engineer, Quantity Surveyor and Builders is the position that had been so familiar generally. Many of people do not aware with Value Management practice in Malaysia. Value Management may be described as a structured, analytical process for developing innovative holistic solutions to complex problems. The objective of this research is to identify the level of awareness on Value Management practice amongst Construction Developers. In this study, the General Manager, Professionals and Project Manager from 34 Developers Company registered under Real Estate and Housing Developers’ Association (REHDA) in Kelantan State has been chosen as respondents. Quantitative methods have been used and 102 sets of questionnaire had been distributed where the returned was only 81 sets. The results indicate that most of the respondents did aware with the Value Management issues in Malaysia. Ultimately, this research paper hoped to contribute in the improvement of the implementation of Value Management in Malaysia especially amongst Developers