Production of defect-poor nanostructured ceramics of yttria-zirconia

For the production of nanostructured ceramics of yttria-zirconia four powders differing in agglomerate strength, agglomerate size and crystallite size are compared. An ultra-fine-grained ceramic with a final density of 98% and a grain size of 0.18 μm could be produced from a hydrothermally crystallized ethanol-washed powder. The remaining porosity is caused by some residual defects which are present due to the irregular shape of the agglomerates and which cause improper die filling. A commercially available powder was also investigated. This powder consists of homogeneous porous, spherical, weak agglomerates. The resulting ceramic has a high density (≥ 99%) but cannot be obtained with ultra-fine grain size (minimum grain size is 0.3 μm). The air-crystallized ethanol-washed powder resulted, after sintering, in larger porosities. In this case the powder consists of weak and some strong agglomerates and a few defect clusters are found in the sintered ceramic which limit the maximum attainable density to 92%. The air-crystallized water-washed powder consists of agglomerates which are too strong to be fractured during compaction. The sintered ceramics contain a large amount of porosity (20%) which is attributed to the presence of inter-agglomerate pores.\u

The effect of pulse stimulation on marine biota - Research in relation to ICES advice - Progress report on the effects on benthic invertebrates

In response to ecosystem related concerns about bottom trawling and particularly beam trawling that were raised by various scientists in the last decades of the previous century. Many studies were done in the 1970s and 1980s, but in spite of promising results commercial uptake was lacking. The development of pulse trawling was again taken up in the 1990s by a private company (Verburg:Holland Ltd.) in The Netherlands. Meanwhile questions about ecosystem effects of introducing pulse beam trawling in the Dutch flatfish fishery were raised by the European Scientific, Technical and Economic Committee for Fisheries (STECF) and the Inter: national Council for the Exploration of the Sea (ICES) and discussed at the meeting of the ICES Working Group on Fishing Technology and Fish Behaviour (WGFTFB) in 2006. These questions led to field strength measurements in situ onboard the commercial beam trawler, and research on the effects of pulse stimulation on cod (Gadus morhua L.), and elasmobranch fish

The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temperatures (1150–1200 °C). The ageing resistance in hot water (185 °C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degradation completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7–9 MPa m1/2 for grain sizes down to 0.2 mgrm. No or very little transformation took place during fracturing and no clear variation with grain size was observed for the toughness at grain sizes up to 0.8 mgrm. Reversible transformation and crack deflection may explain the observed toughness values

Pharmacokinetics of fosfomycin in patients with prophylactic treatment for recurrent Escherichia coli urinary tract infection

Objectives: To evaluate the pharmacokinetics and clinical effectiveness of IV and oral fosfomycin treatment in patients with recurrent urinary tract infection (rUTI) with Escherichia coli. Patients and methods: Patients with rUTI treated with 3 g of oral fosfomycin every 72 h for at Least 14 days were included in a prospective open-Label single-centre study. Serum samples were taken after oral and IV administration of fosfomycin. Urine was collected for 24 h on 3 consecutive days. Fosfomycin concentrations in serum and urine were analysed using validated LC-MS/MS. Pharmacokinetics were evaluated using a population model. EudraCT number 2018-000616-25. Results: Twelve patients were included, of whom nine were also administered IV fosfomycin. Data were best described by a two-compartment model with Linear elimination and a transit-absorption compartment. Median values for absolute bioavailability and serum half-Life were 18% and 2.13 h, respectively. Geometric mean urine concentrations on Days 1, 2 and 3 were above an MIC of 8 mg/L after both oral and IV administration. Quality of Life reported on a scale of 1-10 increased from 5.1 to 7.4 (P= 0.001). The average score of UTI symptoms decreased after fosfomycin dosing (by 3.1 points, 95% CI = -0.7 to 7.0, P= 0.10). Conclusions: Oral fosfomycin at 3 g every 72 h provides plasma and urine concentrations of fosfomycin above the MIC for E. coli. This pharmacokinetic model can be used to develop optimal dosing regimens of fosfomycin in patients with UTI

Microstructure and thermal stability of Fe, Ti and Ag implanted Yttria-stabilized zirconia

Yttria-stabilized zirconia (YSZ) was implanted with 15 keV Fe or Ti ions up to a dose of 8×1016 at cm−2. The resulting “dopant” concentrations exceeded the concentrations corresponding to the equilibrium solid solubility of Fe2O3 or TiO2 in YSZ. During oxidation in air at 400° C, the Fe and Ti concentration in the outermost surface layer increased even further until a surface layer was formed of mainly Fe2O3 and TiO2, as shown by XPS and ISS measurements. From the time dependence of the Fe and Ti depth profiles during anneal treatments, diffusion coefficients were calculated. From those values it was estimated that the maximum temperature at which the Fe- and Ti-implanted layers can be operated without changes in the dopant concentration profiles was 700 and 800° C, respectively. The high-dose implanted layer was completely amorphous even after annealing up to 1100° C, as shown by scanning transmission electron microscopy. Preliminary measurements on 50 keV Ag implanted YSZ indicate that in this case the amorphous layer recrystallizes into fine grained cubic YSZ at a temperature of about 1000° C. The average grain diameter was estimated at 20 nm, whereas the original grain size of YSZ before implantation was 400 nm. This result implies that the grain size in the surface of a ceramic material can be decreased by ion beam amorphisation and subsequent recrystallisation at elevated temperatures