Identifikovanje karakteristika difuzije kroz gleđno tkivo zuba mačke oštećenog resorptivnim procesom

Various factors have been suggested in the pathogenesis of feline resorptive lesions, such as periodontal disease, dietary factors, mechanical stress, developmental tooth defects, breed and viral disease, although none of these factors have been definitively proven to be the direct cause. It was recently published that normally enamel in cats is significantly thinner at the cemento-enamel junction, and both enamel and dentine are significantly less mineralized than elsewhere on the tooth. However, it is still unclear what anatomical features of the tooth surface are associated with a predisposition for resorptive lesions, and what is the initiating cause for the clastic activity afterwards. The present study was undertaken with the aim to describe enamel properties of transport and distribution of organic molecules in intact feline teeth and teeth affected with resorptive lesions. The results indicate that damaged enamel is prone to a greater bilateral diffusion process, leading to continuous disruption of the enamel structure. Also, teeth that are subjected to occlusal stress are at greater risk of destruction because micro fractures produce disarrangements in feline dental tissue diffusion homeostasis. The relationship between these features with feline dental resorptive lesions requires further studies.U patogenezi dentalnih resorptivnih lezija u mačaka pominju se različiti etiološki faktori kao što su oboljenja parodontalnih tkiva, faktori načina ishrane, mehaničko opterećenje, defekti nastali u toku razvoja zuba i virusna oboljenja. Ni za jedan od navedenih faktora do sada nije potvrđeno da je direktan uzročnik lezija. Nedavno je objavljeno da je gleđ u mačaka na gleđno-cementnoj granici značajno tanja od ostale gleđi, kao i da su gleđ i dentin tog područja mnogo manje mineralizovani nego na ostalim delovima zuba. Ipak nije potvrđeno da li postoje i posebni anatomski delovi zuba koji imaju predispoziciju za nastajanje resorptivnih lezija i šta je inicijalni faktor za kasnije aktiviranje odontoklasta. Istraživanje je sprovedeno sa ciljem da se ispita distribucija i transport organskih molekula intaktne gleđi zuba mačke i gleđi koja je zahvaćena resorptivnim procesom. Rezultati istraživanja prikazuju da je oštećena gleđ podložnija intenzivnijem bilateralnom procesu difuzije, koja dovodi do kontinualnog oštećivanja strukture gleđi. Zubi koji su izloženi okluzalnom opterećenju su takođe pod većim rizikom od propadanja jer mikropukotine koje nastaju usled koncentracije napona uzrokuju poremećaj homeostaze dentalnih tkiva. Utvrđivanje povezanosti faktora difuzije i mehaničkog opterećenja zahteva dodatna istraživanja

A milestone in the era of esports: The Olympics through the lens of virtual reality

Whether the International Olympic Committee (IOC) ever includes electronic sports (esports) in the official program of the Olympic Games, the popularity of competitive gaming continues to grow—sports present a modern audience powerhouse the world cannot fail to notice. By the end of 2025, the number of viewers in esports is expected to reach 640.8 million and revenue growth of 1,866.2 billion U.S. dollars (Gough, 2022). Over 170 colleges in the United States have established varsity esports teams and offer esports players' educational opportunities, including partial or full scholarships (Lyman, 2022). Esports has also found its place in schools, largely influencing the youth (Rothwell and Shaffer, 2019). Additionally, numerous NBA teams have entered the esports race, and even Usain Bolt owns an esports team (Gardner, 2022), perhaps better illustrating esports' global prevalence. In 2021, the IOC took a step closer to the digital world, creating the Olympic Virtual Series (OVS). The main objective was to promote the development of virtual sports games and engage with the gaming communities worldwide. The OVS consisted of five different games: baseball (Powerful Pro Baseball 2020), cycling (Zwift), rowing (World rowing, using a rowing machine), sailing (Virtual Regatta), and motor racing (Gran Turismo). The IOC fused traditional elements of sport physicality and video games to uniquely incorporate physical activity (PA) to new audiences, connecting “e” and sports through the Olympic Movement (Palaar, 2021). Opposingly, the 2022 Asian Games (postponed to 2023 due to COVID-19) in Hangzhou will be the first official continental competition to include eight esports games played on computers, consoles, and even smartphone devices (Daniels, 2021). While these actions by the IOC certainly took cognizance of esports and presented it to a world audience, none of the included games utilized virtual reality (VR) technology. Compared to the vast library of traditional esports games (e.g., Dota 2, League of Legends, Apex, CS:GO), VR games have a small selection of titles—which has affected the global VR prevalence in the gaming world. However, an excellent example is the VR game Onward, which (according to players) brought new features and a higher skill ceiling than traditional games, in addition to the physical embodiment and “immersiveness” for players (Turkay et al., 2021). VR is defined as an immersive and multisensory experience for the user, with the support of multimedia components such as VR headset and body tracking sensors (Gigante, 1993). As opposed to the 360° VR, which relies on the video recorded by the actual camera and then implemented into the system—this gives users a more realistic view and experience. However, both rely on the physical headset device with or without motion controllers. VR and the gaming industry joint became more evident as VR became a globally more available technology (e.g., Oculus Rift, HTC Vive, PlayStation) on the market. While the VR player base is not as big as Dota 2 or CS:GO, VR esports have a promising future with exponential growth, forecasted to reach 2.4 billion U.S dollars by 2024 (Clement, 2022). Besides games, VR technology has wide application in the rehabilitation of specific populations, psychology, psychiatry, education, and even sports performance (Lange et al., 2010; Salem and Elokda, 2014; Izard et al., 2018; Michalski et al., 2019; Park et al., 2019; Kaplan et al., 2021; Lee et al., 2021)

The Impact of One Heat Treated Contact Element on the Coefficient of Static Friction

The subject of the paper includes theoretical considerations, the conducting of experimental tests, and the analysis of exposed test results related to determination of the coefficient of static friction of previously heat-treated contact pairs. One contact element is previously, before the procedure of determining the coefficient of static friction, heated at temperatures in the range of ambient temperature to 280°C and then cooled down to ambient temperature. The results of experimental tests of five different materials show that depending on the heat treatment of one contact element, there is a significant decrease in the coefficient of static friction. The authors of the paper consider that the reasons for the decreasing coefficient of static friction are related to oxide formation and changes in the surface layer of the contact element which is previously heat-treated

Mechanical properties and microstructure characterisation of Au-Pt dental alloy

Development of a dental alloy with high Au content is based on the ternary system of Au-Pt-Zn with a nominal composition of 86,9Au-9,9Pt-1,5Zn, and about 1,5 wt.% micro-alloying elements (in, Ir, Rh). The results analyses of different heat-treated states showed that the optimal mechanical properties and hardness of an Au-Pt-Zn alloy can be reached with combinations of heat treatment for 20 minutes at 723 K and then slowly cooling, if the alloy was annealed at 1223 K for 30 minutes and the water quenched. Research results confirmed that the microstructure of the Au-Pt-Zn alloy consists of two phases: alpha(1)-phase rich in Au (main phase) and alpha(2)-phase rich in Pt (minor phase). During XRD analysis and use of the Rietveld method, it was found that the alpha(1)-phase content is about 98,5 wt.% while the content of alpha(2)-phase is 1,5 wt.%. STA analyses show that the Au-Pt-Zn alloy has a solidus temperature of about 1292 K and a liquidus temperature of about 1412 K

Mean field approximation of two coupled populations of excitable units

The analysis on stability and bifurcations in the macroscopic dynamics exhibited by the system of two coupled large populations comprised of $N$ stochastic excitable units each is performed by studying an approximate system, obtained by replacing each population with the corresponding mean-field model. In the exact system, one has the units within an ensemble communicating via the time-delayed linear couplings, whereas the inter-ensemble terms involve the nonlinear time-delayed interaction mediated by the appropriate global variables. The aim is to demonstrate that the bifurcations affecting the stability of the stationary state of the original system, governed by a set of 4N stochastic delay-differential equations for the microscopic dynamics, can accurately be reproduced by a flow containing just four deterministic delay-differential equations which describe the evolution of the mean-field based variables. In particular, the considered issues include determining the parameter domains where the stationary state is stable, the scenarios for the onset and the time-delay induced suppression of the collective mode, as well as the parameter domains admitting bistability between the equilibrium and the oscillatory state. We show how analytically tractable bifurcations occurring in the approximate model can be used to identify the characteristic mechanisms by which the stationary state is destabilized under different system configurations, like those with symmetrical or asymmetrical inter-population couplings.Comment: 5 figure

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation

Silencing of germacrene A synthase genes reduces guaianolide oxalate content in <i>Cichorium intybus</i> L.

Chicory (Cichorium intybus L.) is a medicinal and industrial plant from the Asteraceae family that produces a variety of sesquiterpene lactones (STLs), most importantly bitter guaianolides: lactucin, lactucopicrin and 8-deoxylactucin as well as their modified forms such as oxalates. These compounds have medicinal properties; however, they also hamper the extraction of inulin – a very important food industry product from chicory roots. The first step in guaianolide biosynthesis is catalyzed by germacrene A synthase (GAS) which in chicory exists in two isoforms – GAS long (encoded by CiGASlo) and GAS short (encoded by CiGASsh). AmiRNA silencing was used to obtain plants with reduced GAS gene expression and level of downstream metabolites, guaianolide-15-oxalates, as the major STLs in chicory. This approach could be beneficial for engineering new chicory varieties with varying STL content, and especially varieties with reduced bitter compounds more suitable for inulin production