ABSTRACT
The crystallite size of the materials considerably influences the material properties, including their compressibility and resistance to external forces and the stability of the crystalline structure; a corresponding study for which, so far, has been limited for the important class of nanocrystalline Rare Earth Sesquioxides (REOs). In the present study, we report the crystallographic structural transitions in nanocrystalline Rare Earth Oxides (REOs) under the influence of pressure, investigated via high-energy X-Ray Diffraction (XRD) measurements. The study has been carried out on three of the REOs, namely Lutetium oxide (Lu2O3), Thulium oxide (Tm2O3) and Europium oxide (Eu2O3) up to the pressures of 33, 22 and 11 GPa, respectively. The diffraction data of Lu2O3 and Tm2O3 suggests the occurrence of irreversible structural transitions from cubic to monoclinic phase, while Eu2O3 showed a transition from the cubic to hexagonal phase. The transitions were found to be accompanied by a collapse in the volume and the resulting Pressure-Volume (P-V) graphs are fitted with the 3rd order Birch-Murnaghan (BM) equation of state (EOS) to estimate the bulk moduli and their pressure derivatives. Our study establishes a qualitative relationship between the crystallite size and various material properties such as the lattice parameters, transition pressure, bulk modulus etc., and strengthens the knowledge regarding the behaviour of this technologically important class of materials.
ABSTRACT
Blood pressure (BP) measurement is an important physiological parameter for human health monitoring, which plays a significant role in the diagnosis of many incurable diseases. However, due to inaccuracies in the different types of BP measuring devices, the calibration of these BP measuring instruments is a major concern for a medical practitioner. Currently, these devices' calibration, testing, and validation are performed using rigorous methods with complex clinical trials and following the available documentary standards. This article describes the design and development of an indigenous mechanical test bench (MTB) system for the testing and calibration of multiple BP devices, as per International Organization of Legal Metrology (OIML) recommended documents e.g., OIML R 16-1 and OIML R 16-2. The developed system can test and calibrate 20 BP devices, simultaneously. The traceability of the developed MTB is established by performing its calibration against the Air Piston Gauge, a national primary vacuum standard. The estimated expanded measurement uncertainty evaluated is found to be ±0.11 mmHg, which is almost one order better than the measurement uncertainty required for the test and calibration of BP measuring instruments as per standard. The MTB has successfully been used to test and calibrate several BP measuring instruments. The data of one such device is reported herein as an indicator of the performance process. The calibration of these BP measuring instruments was performed in the static mode, and the estimated expanded measurement uncertainty was found to be ±1.25 mmHg. The developed MTB system would prove to be an excellent instrument for calibration laboratories, hospitals, regulatory agencies, and other users to test and calibrate 20 BP measuring devices simultaneously and cost-effectively.
