Structural and mechanical properties of graded composite Al2O3/Ni obtained from slurry of different solid content

AbstractIn this work, an alumina-nickel graded hollow cylinders were prepared by the centrifugal slip casting. In the paper, the results for samples formed from slurries with different solid content: 45 vol.%, 40 vol.% and 35 vol.% are presented. The structure of the samples after sintering was examined by X-ray diffraction (XRD). The microstructure of the composite, especially the nickel particle size distributions were investigated by using scanning electron microscopy (SEM). An image analyzer has been used for the measurement of volume fraction of the nickel particles in the composites. The hardness was measured by using a Vickers hardness-testing. Based on hardness measurements KIC value were determined. The XRD results confirmed only two phases: Ni and α-Al2O3 in all samples. The preliminary macroscopic observation as well as SEM showed, that the microstructure of the sample cross-section is not homogeneous. Microstructural characterization revealed the gradation of nickel content along the radial direction of hollow cylinder. Three zones were distinguished, from outer surface towards the inner side of the tube. The maximum of volume fraction of nickel particles was obtained at the middle zone of the composites. The results of hardness-testing revealed that the maximum hardness values were observed in region at the inner edge of the casting due to an absence of nickel particles

Clinicians' Ability to Detect a Palpable Difference in Spinal Stiffness Compared With a Mechanical Device.

OBJECTIVE: The purpose of this study was to quantify the threshold at which clinicians can detect a difference in spinal stiffness of the thoracic and lumbar spine via palpation and then determine if this detection threshold would affect a clinician's ability to identify changes in spinal stiffness as measured by an objective instrument. METHODS: In this study, the threshold at which a change in spinal stiffness was detected was quantified in 12 experienced clinicians (physical therapists and doctors of chiropractic) by changing the differential stiffness in 2 inflatable targets until the clinician could no longer identify which was stiffer. In the second part of the study, clinicians then were asked to palpate pre-identified pairs of vertebrae in an asymptomatic volunteer and to identify the stiffer of the pair (T7 and L3, T7 and L4, L3 and L4), and the biomechanical stiffness of each vertebral pair was quantified objectively by a validated instrument. RESULTS: The mean stiffness detection threshold for the clinicians was 8%. Objective measurement of the stiffness differential between vertebral pairs was 30% for T7* and L3, 20% for T7* and L4, and 10% for L3* and L4 (*denotes the stiffer of the pair). Ten of 12 clinicians correctly identified T7 as stiffer when compared with L3 and T7 as stiffer than L4. Alternatively, when the differential vertebral pair stiffness was similar to the stiffness detection threshold (~8%), clinicians were less successful in identifying the stiffer vertebra of the pair; 4 of 12 clinicians correctly identified L3 as being stiffer compared with L4. CONCLUSION: These results suggest that the physiological limits of human palpation may limit the ability of clinicians to identify small alterations in spine stiffness

ECFS best practice guidelines: the 2018 revision

Developments in managing CF continue to drive dramatic improvements in survival. As newborn screening rolls-out across Europe, CF centres are increasingly caring for cohorts of patients who have minimal lung disease on diagnosis. With the introduction of mutation-specific therapies and the prospect of truly personalised medicine, patients have the potential to enjoy good quality of life in adulthood with ever-increasing life expectancy. The landmark Standards of Care published in 2005 set out what high quality CF care is and how it can be delivered throughout Europe. This underwent a fundamental re-write in 2014, resulting in three documents; center framework, quality management and best practice guidelines. This document is a revision of the latter, updating standards for best practice in key aspects of CF care, in the context of a fast-moving and dynamic field. In continuing to give a broad overview of the standards expected for newborn screening, diagnosis, preventative treatment of lung disease, nutrition, complications, transplant/end of life care and psychological support, this consensus on best practice is expected to prove useful to clinical teams both in countries where CF care is developing and those with established CF centres. The document is an ECFS product and endorsed by the CF Network in ERN LUNG and CF Europe

A univalence criterion for meromorphic functions

A sufficient univalence condition for meromorphic functions is give

Quantitative Description of the Spinel Phase (NiAl2O4) Located into Al2O3 Matrix

The presented work focuses on the quantitative description of the spinel phase (NiAl2O4) located into Al2O3 matrix. Three series of samples were prepared. Series I, II and III containing following amount of nickel powder: 0.21% vol, 0.43% vol and 1.3% vol respectively. In order to obtain nickel aluminate spinel sintering was carried out in an oxidizing atmosphere (air). Based on the SEM observation and XRD analysis the presence of spinel phase was confirmed in all samples. Difference in volume fraction of the Ni in the compacts before sintering, resulted in the different content of the spinel phase in the final material. All tested composites were characterized by homogeneous distribution of NiAl2O4 in the whole volume of the material. The purpose of the study was also the use the stereological analysis to determine the shape parameters of new phase

Microstructure Characterization of Composite from ZrO2 – Ti System

In this work the microstructure analysis of composite from ZrO2 – Ti system were presented. For the preparation of the composite samples nanometric ZrO2 powder stabilized by 3 mol% of Y2O3 and micrometric titanium powder were used. The composites with 10 vol.% addition of titanium particles were prepared by slip casting method. The sintering process was conducted at 1450°C with 2 hours’ dwell time, in the inert atmosphere of argon. The microstructure observations were carried out with the use of SEM and STEM microscopes. The quantitative analysis and stereological characterization were performed. The SEM and STEM observations allowed characterizing the microstructure of composite samples. Especially, the interface between titanium particles and zirconia matrix was described. The growth of the zirconia grains around the Ti rich areas was observed. The increase of the zirconia grains size results from the reaction on the interface between titanium particle and zirconia matrix during the sintering process

Quantitative Description of the Spinel Phase (NiAl2O4) Located into Al2O3 Matrix

The presented work focuses on the quantitative description of the spinel phase (NiAl2O4) located into Al2O3 matrix. Three series of samples were prepared. Series I, II and III containing following amount of nickel powder: 0.21% vol, 0.43% vol and 1.3% vol respectively. In order to obtain nickel aluminate spinel sintering was carried out in an oxidizing atmosphere (air). Based on the SEM observation and XRD analysis the presence of spinel phase was confirmed in all samples. Difference in volume fraction of the Ni in the compacts before sintering, resulted in the different content of the spinel phase in the final material. All tested composites were characterized by homogeneous distribution of NiAl2O4 in the whole volume of the material. The purpose of the study was also the use the stereological analysis to determine the shape parameters of new phase