2D materials
Dotaz
Zobrazit nápovědu
The human body involves a large number of systems subjected to contact stresses and thus experiencing wear and degradation. The limited efficacy of existing solutions constantly puts a significant financial burden on the healthcare system, more importantly, patients are suffering due to the complications following a partial or total system failure. More effective strategies are highly dependent on the availability of advanced functional materials demonstrating excellent tribological response and good biocompatibility. In this article, we review the recent progress in implementing two-dimensional (2D) materials into bio-applications involving tribological contacts. We further summarize the current challenges for future progress in the field.
PURPOSE OF THE STUDY The aim of the study was to assess the accuracy of axis deformity correction achieved by high-tibial valgus osteotomy either without or with a computer-assisted kinematic navigation system, on the basis of comparing the planned and the achieved frontal axis of the leg. Comparisons of mechanical axis deviation were made using both pre- and post-operative measurements with the planning software and intra-operative measurements with the navigation system before and after osteotomy. In addition, the aim was to test the hypothesis that the use of 3D navigation, as compared with 2D navigation, would help reduce changes in the tibial plateau slope. MATERIAL AND METHODS In the period 2008-2011, high-tibial osteotomy was performed in 68 patients. Twenty-one patients (group 1) underwent osteotomy without the use of navigation and 47 patients (group 2) had osteotomy with a computer-assisted navigation system (32 with 2D navigation and 15 with 3D navigation). Using the planning software, the mechanical leg axis before and after surgery and the anatomical dorsal proximal tibial angle in the sagittal plane were assessed. Medial opening-wedge high-tibial valgus osteotomy was carried out in all patients. When using 2D navigation, the mechanical leg axis was measured intra-operatively before osteotomy and then after osteosynthesis which included a simulated axial load of the heel. When using 3D navigation, the procedure was identical and furthermore involved a measurement of the tibial plateau slope obtained with an additional probe in the proximal fragment. The results were characterised using descriptive statistics and their significance was evaluated using the Mann-Whitney U test and Wilcoxon's test, with the level of significance set at p < 0.05. RESULTS In group 1, osteotomy resulted in good correction of the mechanical axis in nine patients (43%), inadequate correction in nine (43%) and overcorrection and three (14%) patients. In group 2 with the use of navigation, accurate correction of the mechanical leg axis was achieved in 24 patients (51%), undercorrection was recorded in 21 (45%) and overcorrection in two (4%) patients. The difference in outcomes between the two groups was not statistically significant (p = 0.73). The average correction of the mechanical axis based on comparing measurements on pre- and post-operative radiographs was 9.1 degrees (range, 5-27 degrees); the average correction of the axis visualised intra-operatively was 8.7 degrees (range, 4-27 degrees). The difference was not significant (p = 0.1615) and confirmed our hypothesis that the accuracy of measuring the mechanical axis was not influenced by the method used. The average change in the dorsal slope of the tibial plateau following osteotomy without navigation was 0.9 degrees (range, -8.9 to 9.0 degrees) and that after osteotomy with intra-operative visualisation of the proximal tibial slope was 0.3 degrees (range, -4 to 4 degrees). This difference was not statistically significant (p = 0.813). DISCUSSION A good clinical outcome of high-tibial valgus osteotomy depends on achieving accurate correction of the mechanical leg axis with partial load transfer to the lateral compartment of the knee. CONCLUSIONS Although the number of cases with good correction was slightly higher in the patients undergoing osteotomy with navigation, the difference was not significant. Intra-operative visualisation of the mechanical axis proved sufficiently accurate on comparison with the pre-operative planning based on weight-bearing radiography of the leg. A simulated axial load of the heel included in the kinematic navigation system does not sufficiently correspond to normal weight-bearing and therefore an undercorrection of the deformity might occur. Using 3D navigation had no marked effect on a change in the slope of the tibial plateau.
- MeSH
- chirurgie s pomocí počítače * MeSH
- dospělí MeSH
- genua valga chirurgie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- osteotomie * MeSH
- senioři MeSH
- tibie chirurgie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
This article presents a study of the dependence of the biocompatibility of a carbon-based material, namely a 2D C/C composite, on mechanical and chemical surface modifications. The mechanical modifications were surface grinding and polishing, and chemical modifications were made by depositing thin layers of pyrolytic carbon, titanium-carbon and DLC layers. Human osteoblast-like MG 63 cells were cultivated on these materials. The densities of the cells after one-day cultivation and after four-day cultivation, and the average cell spreading area after one-day cultivation, were evaluated in dependence on particular surface roughness parameters. The minima of the cell density on pyrolytic carbon and titanium-carbon layers were found; they were connected with the maxima of the average cell area. For DLC, the cell area decreased as the roughness parameter Ra increased in the range 0.1-10 µm, although the minimum appeared for the density of the cells. Using a multivariate test, the dependences of the biocompatibility parameters on the layer material and on surface grinding were statistically significant. The results suggest that the optimal roughness parameters for MG 63 cell on carbon based surface were Ra ∼ 3.5 µm, RSm ∼0.03-0.08 mm, Rsk ∼0 or negative and Rku ∼ 20, DLC being the best material choice. These values of roughness were obtained by simple mechanical grinding of substrate and coating by DLC layer.
- MeSH
- biokompatibilní materiály chemie MeSH
- buněčné linie MeSH
- lidé MeSH
- osteoblasty cytologie MeSH
- povrchové vlastnosti MeSH
- proliferace buněk MeSH
- titan chemie MeSH
- uhlík chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Due to their attractive band gap properties and van der Waals structure, 2D binary chalcogenide materials have been widely investigated in the last decade, finding applications in several fields such as catalysis, spintronics, and optoelectronics. Ternary 2D chalcogenide materials are a subject of growing interest in materials science due to their superior chemical tunability which endows tailored properties to the devices prepared thereof. In the family of AIIBIII2XVI4, ordered ZnIn2S4-like based photocatalytic systems have been studied meticulously. In contrast, reports on disordered phases appear to a minor extent. Herein, a photoelectrochemical (PEC) detector based on the pseudo-binary MnIn2Se4 system is presented. A combination of optical measurements and DFT calculations confirmed that the nature of the bandgap in MnIn2Se4 is indirect. Its performance outclasses that of parent compounds, reaching responsivity values of 8.41 mA W-1. The role of the non-centrosymmetric crystal structure is briefly discussed as a possible cause of improved charge separation of the photogenerated charge carriers.
- Publikační typ
- časopisecké články MeSH
In response to the growing need for development of modern biomaterials for applications in regenerative medicine strategies, the research presented here investigated the biological potential of two types of polymer nanocomposites. Graphene oxide (GO) and partially reduced graphene oxide (rGO) were incorporated into a poly(ε-caprolactone) (PCL) matrix, creating PCL/GO and PCL/rGO nanocomposites in the form of membranes. Proliferation of osteoblast-like cells (human U-2 OS cell line) on the surface of the studied materials confirmed their biological activity. Fluorescence microscopy was able to distinguish the different patterns of interaction between cells (depending on the type of material) after 15 days of the test run. Raman micro-spectroscopy and two-dimensional correlation spectroscopy (2D-COS) applied to Raman spectra distinguished the nature of cell-material interactions after only 8 days. Combination of these two techniques (Raman micro-spectroscopy and 2D-COS analysis) facilitated identification of a much more complex cellular response (especially from proteins) on the surface of PCL/GO. The presented approach can be regarded as a method for early study of the bioactivity of membrane materials.
- MeSH
- grafit * farmakologie chemie MeSH
- lidé MeSH
- osteoblasty MeSH
- polyestery chemie MeSH
- polymery MeSH
- Ramanova spektroskopie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Cíl: Zjistit míru vzájemné zastupitelnosti 3 různých digitálních rentgenogramů pro určování polohy retinovaných horních špičáků – kefalometrického snímku, CBCT a kefalometrického snímku generovaného z CBCT pomocí určení opakovatelnosti a reprodukovatelnosti měření pozice retinovaného zubu. Materiál a metodika: Soubor tvořili pacienti ortodontického oddělení Kliniky zubního lékařství LF UP a FN Olomouc a Stomatologické kliniky UK a FN Hradec Králové. Z nich byli vybráni pacienti s retencí horního špičáku, kde byl před léčbou indikován kefalometrický a posléze i CBCT snímek, celkem 43 pacientů s 51 palatinálně retinovanými špičáky. Na kefalometrickém snímku, CBCT a kefalometrickém snímku generovaném z CBCT byla měřena vzdálenost hrotu špičáku a úhel dlouhé osy retinovaného špičáku k okluzní rovině. Ke zjištění spolehlivosti měření na digitálních rentgenových snímcích a ke zjištění míry vzájemné zastupitelnosti digitálních rentgenogramů zhotovených třemi různými způsoby byla hodnocena opakovatelnost a reprodukovatelnost měření. Výsledky: Byla prokázána dobrá míra opakovatelnosti určení polohy špičáků pro všechna tři rentgenová zobrazení. Reprodukovatelnost měření polohy retinovaných špičáků určením vertikální vzdálenosti hrotu vůči okluzní rovině byla dobrá, ale výsledky měření reprodukovatelnosti sklonu dlouhé osy špičáku k okluzní rovině se u jednotlivých rentgenových snímků lišily. Měření dále prokázala velkou soustavnou odchylku (bias) naměřených hodnot u úhlových měření mezi CBCT a digitálními kefalometrickými snímky nebo počítačově generovanými z CBCT snímků. Závěr: Měření sklonu dlouhé osy špičáku k okluzní rovině není možné volně zaměnit mezi CBCT a 2D kefalometrickými snímky. Vertikální vzdálenost hrotu špičáku od okluzní roviny je jediným parametrem, u kterého je možné měření na 2D a 3D rentgenech vzájemně zaměnit.
Aims: We wanted to establish the degree of mutual substitutability of 3 different digital radiograms in defining location of impacted upper canines – cephalogram, CBCT, and cephalogram generated from CBCT, with the help of repeatability and reproducibility of measurement of an impacted tooth location. Material and method: The sample included patients of orthodontic departments of the Institute of Dentistry and Oral Sciences, Faculty of Medicine and Dentistry, Palacky University and University Hospital Olomouc and the Clinic of Stomatology, Charles University and University Hospital Hradec Králové. We selected the patients with impacted upper canine with cephalogram and CBCT taken prior to treatment – 43 patients, 51 palatally impacted canines. The distance between canine cusp and occlusal plane, and angle of a long axis of impacted canine to occlusal plane were measured in cephalograms, CBCTs and in cephalograms generated from CBCT. To establish reliability of mesurement in digital radiographs and mutual substitutability of digital radiograms made by three different techniques repeatability and reproducibility of measurement was evaluated. Results: A good degree of repeatability of identification of canines location was proved in all three radiographic methods. Reproducibility of measurement of impacted canines location by defining vertical distance between canine cusp and occlusal plane was good, however, the results of reproducibility of canine long axis inclination to occlusal plane varied in different types of radiographs. Furthermore, measurements showed a big bias of values of angular measurements between CBCT and digital cephalograms or generated from CBCT scans. Conclusion: Measurement of canine long axis inclination to occlusal plane is different in CBCT and 2D cephalograms. Vertical distance between canine cusp and occlusal plane is the only parameter the measurements of which are substitutable (2D and 3D).
Recent research has highlighted the pivotal role of lipoxygenases in modulating ferroptosis and immune responses by catalyzing the generation of lipid peroxides. However, the limitations associated with protein enzymes, such as poor stability, low bioavailability, and high production costs, have motivated researchers to explore biomimetic materials with lipoxygenase-like activity. Here, we report the discovery of lipoxygenase-like two-dimensional (2D) MoS2nanosheets capable of catalyzing lipid peroxidation and inducing ferroptosis. The resulting catalytic products were successfully identified using mass spectrometry and a luminescent substrate. Unlike native lipoxygenases, MoS2 nanosheets exhibited exceptional catalytic activity at extreme pH, high temperature, high ionic strength, and organic solvent conditions. Structure-activity relationship analysis indicates that sulfur atomic vacancy sites on MoS2 nanosheets are responsible for their catalytic activity. Furthermore, the lipoxygenase-like activity of MoS2 nanosheets was demonstrated within mammalian cells and animal tissues, inducing distinctive ferroptotic cell death. In summary, this research introduces an alternative to lipoxygenase to regulate lipid peroxidation in cells, offering a promising avenue for ferroptosis induction.
- MeSH
- biomimetické materiály chemie farmakologie metabolismus MeSH
- disulfidy * chemie metabolismus MeSH
- ferroptóza * účinky léků MeSH
- katalýza MeSH
- lidé MeSH
- lipoxygenasa * metabolismus chemie MeSH
- molybden chemie metabolismus MeSH
- myši MeSH
- nanostruktury chemie MeSH
- peroxidace lipidů MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Cardiovascular magnetic resonance (CMR) 2D feature tracking (FT) left ventricular (LV) myocardial strain has seen widespread use to characterize myocardial deformation. Yet, validation of CMR FT measurements remains scarce, particularly for regional strain. Therefore, we aimed to perform intervendor comparison of 3 different FT software against tagging. METHODS: In 61 subjects (18 healthy subjects, 18 patients with chronic myocardial infarction, 15 with dilated cardiomyopathy, and 10 with LV hypertrophy due to hypertrophic cardiomyopathy or aortic stenosis) were prospectively compared global (G) and regional transmural peak-systolic Lagrangian longitudinal (LS), circumferential (CS) and radial strains (RS) by 3 FT software (cvi42, Segment, and Tomtec) among each other and with tagging at 3T. We also evaluated the ability of regional LS, CS, and RS by different FT software vs tagging to identify late gadolinium enhancement (LGE) in the 18 infarct patients. RESULTS: GLS and GCS by all 3 software had an excellent agreement among each other (ICC = 0.94-0.98 for GLS and ICC = 0.96-0.98 for GCS respectively) and against tagging (ICC = 0.92-0.94 for GLS and ICC = 0.88-0.91 for GCS respectively), while GRS showed inconsistent agreement between vendors (ICC 0.10-0.81). For regional LS, the agreement was good (ICC = 0.68) between 2 vendors but less vs the 3rd (ICC 0.50-0.59) and moderate to poor (ICC 0.44-0.47) between all three FT software and tagging. Also, for regional CS agreement between 2 software was higher (ICC = 0.80) than against the 3rd (ICC = 0.58-0.60), and both better agreed with tagging (ICC = 0.70-0.72) than the 3rd (ICC = 0.57). Regional RS had more variation in the agreement between methods ranging from good (ICC = 0.75) to poor (ICC = 0.05). Finally, the accuracy of scar detection by regional strains differed among the 3 FT software. While the accuracy of regional LS was similar, CS by one software was less accurate (AUC 0.68) than tagging (AUC 0.80, p < 0.006) and RS less accurate (AUC 0.578) than the other two (AUC 0.76 and 0.73, p < 0.02) to discriminate segments with LGE. CONCLUSIONS: We confirm good agreement of CMR FT and little intervendor difference for GLS and GCS evaluation, with variable agreement for GRS. For regional strain evaluation, intervendor difference was larger, especially for RS, and the diagnostic performance varied more substantially among different vendors for regional strain analysis.
- MeSH
- funkce levé komory srdeční MeSH
- gadolinium MeSH
- kontrastní látky * MeSH
- lidé MeSH
- magnetická rezonance kinematografická * MeSH
- magnetická rezonanční spektroskopie MeSH
- prediktivní hodnota testů MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
OBJECTIVES: The second-to-fourth digit ratio (2D:4D ratio) can be assumed a valid indicator of sexual differentiation, provided that it is stable once it develops, or eventual changes remain uniform in a respective cohort throughout ontogenesis. The main goal of this study was to determine whether the metacarpal 2M:4M and the digit 2D:4D ratio change during the period of pubertal/adolescent growth. MATERIALS AND METHODS: The metacarpals and digits were measured on radiographs of left hands in the sample of 328 individuals (96 pairs of male and 68 pairs of female twins) from the Wrocław Longitudinal Study of Twins (1967-1983). Five consecutive annual measurements were done for each individual within a 4-year-interval somewhere between 7 and 18 years of age. Age-related changes in both ratios were studied using a set of mixed-effects linear models. Three types of correlation coefficients were used for assessment of stability between repeated measurements at different ages. RESULTS: An overall decrease in the average 2M:4M ratio was observed, attributable to a much larger extent to males than to females. On the contrary, a slight overall increase in the average 2D:4D ratio was observed, attributable to a much larger extent to females than to males. The rank order of the ratios remained highly stable within the monitored period (the correlation coefficient mostly ranged between 0.85 and 0.95). In spite of these findings, we recorded significant intraindividual changes in both ratios. In some individuals the 2D:4D ratio can undergo changes comparable to average sex differences and much higher than average age-related changes. DISCUSSION: Relatively slight overall changes in digit ratio in puberty and adolescence themselves are not inconsistent with the use of the 2D:4D ratio as an indirect marker of prenatal sexual differentiation. Nevertheless, individual changes in the ratios varied substantially in this study and differed from the average trends. Future studies should focus on the nature of interindividual developmental differences in the digit and metacarpal ratios.
- MeSH
- antropologie fyzická MeSH
- antropometrie MeSH
- dítě MeSH
- dvojčata MeSH
- lidé MeSH
- longitudinální studie MeSH
- mladiství MeSH
- pohlavní dimorfismus MeSH
- pohlavní dospělost MeSH
- prsty ruky anatomie a histologie MeSH
- puberta fyziologie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
