957 resultados para PMN-PT ceramic
Resumo:
The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP).
Resumo:
We present a multistage strategy to define the scale and geographic distribution of 'local' ceramic production at Lydian Sardis based on geochemical analysis (NAA) of a large diverse ceramic sample (n = 281). Within the sphere of local ceramic production, our results demonstrate an unusual pattern of reliance on a single resource relative to other contemporary Iron Age centers. When our NAA results are combined with legacy NAA provenience data for production centers in Western Anatolia, we can differentiate ceramic emulation from exchange, establish probable proveniences for the non-local component of the dataset, and define new non-local groups with as yet no known provenience. (C) 2012 Elsevier Ltd. All rights reserved.
Resumo:
Changes in resource use over time can provide insight into technological choice and the extent of long-term stability in cultural practices. In this paper we re-evaluate the evidence for a marked demographic shift at the inception of the Early Iron Age at Troy by applying a robust macroscale analysis of changing ceramic resource use over the Late Bronze and Iron Age. We use a combination of new and legacy analytical datasets (NAA and XRF), from excavated ceramics, to evaluate the potential compositional range of local resources (based on comparisons with sediments from within a 10 km site radius). Results show a clear distinction between sediment-defined local and non-local ceramic compositional groups. Two discrete local ceramic resources have been previously identified and we confirm a third local resource for a major class of EIA handmade wares and cooking pots. This third source appears to derive from a residual resource on the Troy peninsula (rather than adjacent alluvial valleys). The presence of a group of large and heavy pithoi among the non-local groups raises questions about their regional or maritime origin. (C) 2012 Elsevier Ltd. All rights reserved.
Resumo:
SUMMARY The aim of this study was to evaluate the influence of surface roughness on surface hardness (Vickers; VHN), elastic modulus (EM), and flexural strength (FLS) of two computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic materials. One hundred sixty-two samples of VITABLOCS Mark II (VMII) and 162 samples of IPS Empress CAD (IPS) were ground according to six standardized protocols producing decreasing surface roughnesses (n=27/group): grinding with 1) silicon carbide (SiC) paper #80, 2) SiC paper #120, 3) SiC paper #220, 4) SiC paper #320, 5) SiC paper #500, and 6) SiC paper #1000. Surface roughness (Ra/Rz) was measured with a surface roughness meter, VHN and EM with a hardness indentation device, and FLS with a three-point bending test. To test for a correlation between surface roughness (Ra/Rz) and VHN, EM, or FLS, Spearman rank correlation coefficients were calculated. The decrease in surface roughness led to an increase in VHN from (VMII/IPS; medians) 263.7/256.5 VHN to 646.8/601.5 VHN, an increase in EM from 45.4/41.0 GPa to 66.8/58.4 GPa, and an increase in FLS from 49.5/44.3 MPa to 73.0/97.2 MPa. For both ceramic materials, Spearman rank correlation coefficients showed a strong negative correlation between surface roughness (Ra/Rz) and VHN or EM and a moderate negative correlation between Ra/Rz and FLS. In conclusion, a decrease in surface roughness generally improved the mechanical properties of the CAD/CAM ceramic materials tested. However, FLS was less influenced by surface roughness than expected.
Resumo:
Conducted work with two potential alternatives to Ni, La0.8Sr0.2Cr0.5Mn0.5 (LSCM) and Sr doped LaVO3 (LSV) to serve as the electron conductor in the anode of solid oxide fuel cells SOFCs.
Resumo:
The migration of polymorphonuclear granulocytes (PMN) into the brain parenchyma and release of their abundant proteases are considered the main causes of neuronal cell death and reperfusion injury following ischemia. Yet, therapies targeting PMN egress have been largely ineffective. To address this discrepancy we investigated the temporo-spatial localization of PMNs early after transient ischemia in a murine transient middle cerebral artery occlusion (tMCAO) model and human stroke specimens. Using specific markers that distinguish PMN (Ly6G) from monocytes/macrophages (Ly6C) and that define the cellular and basement membrane boundaries of the neurovascular unit (NVU), histology and confocal microscopy revealed that virtually no PMNs entered the infarcted CNS parenchyma. Regardless of tMCAO duration, PMNs were mainly restricted to luminal surfaces or perivascular spaces of cerebral vessels. Vascular PMN accumulation showed no spatial correlation with increased vessel permeability, enhanced expression of endothelial cell adhesion molecules, platelet aggregation or release of neutrophil extracellular traps. Live cell imaging studies confirmed that oxygen and glucose deprivation followed by reoxygenation fail to induce PMN migration across a brain endothelial monolayer under flow conditions in vitro. The absence of PMN infiltration in infarcted brain tissues was corroborated in 25 human stroke specimens collected at early time points after infarction. Our observations identify the NVU rather than the brain parenchyma as the site of PMN action after CNS ischemia and suggest reappraisal of targets for therapies to reduce reperfusion injury after stroke.