Preparation and Characteristics of High-Performance, Low-Density Metallo-Ceramics Composite.

By applying the physical vapour deposition method, hollow ceramic microspheres were coated with titanium, and subsequently, they were sintered using the spark plasma sintering technique to create a porous ceramic material that is lightweight and devoid of a matrix. The sintering process was carried out at temperatures ranging from 1050 to 1200 °C, with a holding time of 2 min. The samples were subjected to conventional thermal analyses (differential scanning calorimetry, thermogravimetry, dilatometry), oxidation resistance tests, and thermal diffusivity measurements. Phase analysis of the samples was performed using the XRD and the microstructure of the prepared specimens was examined using electron microscopy. The titanium coating on the microspheres increased the compressive strength and density of the resulting ceramic material as the sintering temperature increased. The morphology of the samples was carefully examined, and phase transitions were also identified during the analysis of the samples.

Ultrahigh Temperature Flash Sintering of Binder-Less Tungsten Carbide within 6 s.

We report on an ultrarapid (6 s) consolidation of binder-less WC using a novel Ultrahigh temperature Flash Sintering (UFS) approach. The UFS technique bridges the gap between electric resistance sintering (≪1 s) and flash spark plasma sintering (20-60 s). Compared to the well-established spark plasma sintering, the proposed approach results in improved energy efficiency with massive energy and time savings while maintaining a comparable relative density (94.6%) and Vickers hardness of 2124 HV. The novelty of this work relies on (i) multiple steps current discharge profile to suit the rapid change of electrical conductivity experienced by the sintering powder, (ii) upgraded low thermal inertia CFC dies and (iii) ultra-high consolidation temperature approaching 2750 °C. Compared to SPS process, the UFS process is highly energy efficient (≈200 times faster and it consumes ≈95% less energy) and it holds the promise of energy efficient and ultrafast consolidation of several conductive refractory compounds.

Pulse oximetric routine examination of sleep apnea in acute stroke (PRESS).

BACKGROUND: Sleep-disordered breathing (SDB) is present in more than 70% of stroke patients. Despite its association with increased morbidity, mortality, and reduced functional outcomes, targeted assessment of SDB in stroke patients, remain controversial. Polysomnography ("gold standard" examination) is a technically demanding and costly test with limited availability. The use of screening questionnaires is limited due to low specificity and sensitivity. Pulse oximetry seems to be a sensible alternative. Our study aimed to assess the feasibility and predictive value of routine pulse oximetric screening for assessment of SDB in patients with acute stroke. METHODS: Patients with acute stroke were enrolled in an open, prospective study. A single-night pulse oximetric assessment was used for SDB screening. Subsequently, polysomnography was performed to confirm SDB. Moderate-to-severe SDB was defined as apnea-hypopnea index ≥15. RESULTS: Out of 420 enrolled patients, refusal to undergo examination was reported in 4 and non-cooperation during the investigation in 21 subjects. The area under the curve in a receiver operating curve to predict moderate-to-severe SDB by desaturation index (DI) was 0.86 (95% CI: 0.76-0.97), and optimal DI cut-off by Youden index was 15.3. Positive pulse oximetric screening (DI ≥ 15.3) had 90.5% sensitivity and 75% specificity to predict moderate-to-severe SDB. CONCLUSIONS: Our results suggest a good adherence of acute stroke patients to the pulse oximetric screening. Pulse oximetry represents a simple, cost-effective, and sensitive examination that might be used in stroke patients as an appropriate tool for further selection for targeted diagnostic and therapeutic processes of SDB in the sleep laboratory.