In this study, 10%PTFE/PEEK blend were modified by potassium titanate whisker (PTW) and chopped glass fiber (GF), respectively. The blends were prepared by three-screw extruder. Through the investigation of thermal stability, tribological properties, mechanical properties and rheological behavior, the effects of reinforcing agents were determined. The results illustrated that the mechanical properties of 10%PTFE/PEEK blend can be dramatically improved by adding reinforcing agent of PTW or GF, and the reinforcing effect of GF was especially obvious. As for tribological properties, 1% addition was the best proportion. The friction coefficient and wear rate of the blend with 1% PTW were 0.283 and 4.97 × 10^-6 mm³/N · m, which decreased by 7.2% and 21% compared with those of the blend without reinforcing agent.

The aim of this article was to evaluate properties of new polymer material, based on PEEK, for FPDs in patients with parafunctions. Methods: Prospective clinical study involved patients with diagnosed signs and symptoms of parafunctions, restored with 100 units, PEEK based FPDs, veneered with composite material. During one year observation period the following parameters were evaluated: color changes, periodontal indices, treatment success using FDI criteria, occlusal parameters, patient-reported outcome measures (OHIP-49) and occurrence of complications. Results: Spectrophotometry revealed that 63% of bridges experienced changes for L*, a*, b* color parameters, but it was not clinically significant for patients. Periodontal indices (PI, GI, BOP) revealed statistically significant higher values around restorations. According to FDI criteria, therapy was considered successful and 86.7% of FPDs were acceptable. Computerized occlusal analysis demonstrated no significant difference in the number of occlusal contacts and the intensity of relative forces between restoration and control side. Results of OHIP-49 questionnaire showed improved patient’s quality of life. Complications appeared in a limited number of cases. Conclusion: PEEK based FPDs could be indicated for successful prosthodontic rehabilitation in patients with parafunctional activities, but further material improvements and long-term clinical trials should be conducted to analyze performance of this material in challenging cases, for patients with CMD and in implant therapy.

Background. January 2021 marked one year since the start of COVID-19 pandemic: it is the time of intermediate conclusions. Objective. To evaluate CFR and IFR due to COVID-19 in various countries and territories, and to study if parameters of a population age affect CFR and IFR. Material and Methods. The databases of 219 countries were collected on the Worldometers, Index Mundi, Country Meters and World Bank websites. The processing of data was divided into two parts: the first part dealt with the calculation and analysis of CFR while the second, the calculation and analysis of IFR. Results. The calculations revealed that in 74 out of 219 countries, CFR was less than 1.00 %, in 69 countries it varied between 1.00 % and 2.00 %, and in 76 countries it was more than 2.00 %. The calculation of IFR revealed that in 183 countries, IFR was less than 1.00 %, in 22 countries IFR was between 1.00 % and 2.00 %, and only in 14 out of 219 countries IFR was more than 2.00 %. A correlation between IFR and parameters of a population age was found: the less median age and the percentage of 'aged' people – the less value of IFR, although, there was no correlation between parameters of a population age and CFR. Conclusion. The global health care system has gone through a year of serious trial caused by COVID-19 and appeared to have emerged victorious. In the majority of countries analyzed, the parameters of mortality due to COVID-19 were at a low level. So, there seems to be an objective basis for optimism and hope for an early end to the pandemic.

Haemodynamic indices are widely used in clinical practice for deciding on a particular type of treatment. Low quality of the CT data and tachycardia complicate interpretation of the measured or simulated values. In this work, we present a novel approach for evaluating resistances in terminal coronary arteries. Using 14 measurements from 10 patients, we show that this algorithm retains the accuracy of 1D haemodynamic simulations in less detailed (truncated) geometric models of coronary networks. We also apply the variable systole fraction model to study the effect of elevated heart rate on the values of FFR, CFR and iFR. We conclude that tachycardia may produce both overestimation or underestimation of coronary stenosis significance.

In this research, a screw-barrel system was designed and implemented, coupled with material extrusion, to print high-melt-temperature thermoplastic materials. The aim was to integrate two methods: the direct extrusion of thermoplastic polymer pellets with material extrusion,utilize various polymers in the form of pellets, especially high melt temperature ones, instead of traditional filaments. This addresses one of the significant challenges in filament preparation for various materials that are not readily available in the market or nearly impossible to fabricate (such as highly filled plastics). First, the screw-barrel assembly performance and factors influencing feed rate were evaluated. Subsequently, specimens were printed with polyether ether ketone (PEEK), an advanced plastic material known for its outstanding mechanical properties, high-temperature tolerance, and broad applications in various sectors, such as medical. Additionally, the material was reinforced with 2.5% continuous glass fibers while printing, which presented a novel product. Upon comparing theoretical values with experimental data from the tensile testing, a notable observation emerged: the inclusion of 2.5% glass fibers led to an approximate 43% increase in the tensile strength of the material. Furthermore, SEM images provided visual evidence of satisfactory adhesion between layers and fibers.

Since identified as the pathogen responsible for an outbreak of severe respiratory distress in Wuhan, China, the 2019-nCoV coronavirus has caused over 30M cases and 1M deaths globally. Sporadic cases were identified in several states in the US from early January, and large-scale community transmission is believed to have started in late February, leading to a first spike in COVID-19 deaths and overall mortality in late April, and a second spike later in the summer. I show here that the dynamics of the pandemic were different in different regions of the US, showing a north-south pattern, with a first pandemic wave mainly in northern regions, followed by a second wave mainly in southern regions. Analysis of overall mortality data shows that the increase in mortality correlates well with COVID-19 incidence in most regions, and that from April through August COVID-19 deaths accounted for a substantial proportion of all deaths in all parts of the US.

late in December 2019 2019-nCoV was identified as the pathogen responsible for an outbreak of severe respiratory distress in Wuhan, China. The virus was detected in multiple countries during January, but it is believed widespread community transmission began late in February or early March. Since March the virus has caused over 100k confirmed deaths in the US, with some states more severely impacted, notably NY and NJ. Here I examine excess mortality at the national and state level from January through July 2020. I find that the increase in excess mortality began in late February, suggesting the pathogen was circulating undetected earlier than assumed. The timing and intensity of the increase in excess mortality varied across states, with two patterns emerging: an early, sharp increase reaching a peak during April-May, best exemplified by NY and NJ, and a shallower, sustained increase, reaching a peak in late July, observed mostly in the southern regions of the US.