Structural phase transitions and magnetic superexchange in MIAgIIF3 perovskites at high pressure

Pressure induced phase transitions of MIAgIIF3 perovskites where M = K, Rb, Cs, have been predicted theoretically for the first time for pressures up to 100 GPa. The sequence of phase transitions for M = K and Rb consists of an orthorhombic to monoclinic and back to orthorhombic transition, associated with progressive bending of infinite chains of corner sharing [AgF6]4 minus octahedra and their mutual approaching via secondary Ag...F contacts. In stark contrast, only a single phase transition i.e. tetragonal to triclinic, is predicted for CsAgF3, associated with substantial deformation of the Jahn Teller-distorted first coordination sphere of AgII and association of the infinite [AgF6]4 minus chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF3 hosts lattices.Comment: 7 pages, 3 figures, and electronic supplement of 25 page

Numerical and experimental analysis of balloon angioplasty impact on flow hemodynamics improvement

Purpose: The paper focuses on the numerical and experimental evaluation of the fluid flow inside chosen fragments of blood vessels. In the first stage of the study, the experimental tests were conducted using a research test stand, designed to be used in this evaluation. The study evaluated the blood flow through a silicone vessel with an implanted coronary stent. Methods: The PIV method was used in order to visualize the flow vectors inside a silicone vessel. Deformed vessel geometry implemented for computational fluid dynamics purposes was obtained owing to a non-linear simulation of the stent expansion (angioplasty process) in a silicone vessel. Additionally, a vessel model with a statistical 55% area stenosis and an irregular real vessel with an atherosclerotic plaque were also subjected to analysis from the hemodynamic flow point of view. A vessel with a statistical stenosis was also used to simulate the angioplasty process, which resulted in obtaining a flow domain for the vessel with an atherosclerotic plaque after the stent implantation. Results: For each case, distributions of parameters such as OSI or TAWSS were also analyzed and discussed. The areas of low TAWSS values appear close to the stent struts. Conclusions: Stents with increased diameters, compared to the normal vessel diameter, create a higher risk of occurrence of the areas with low WSS values. Excessive stent deformation can cause inflammation by injuring the vessel and can initiate the restenosis and thrombotic phenomena through the increased vessel diameter

Biomechanical assessment with use of orthopedic equipment

Dotychczasowe badania z wykorzystaniem sprzętu ortopedycznego, takiego jak ortezy czy gorsety, miały na celu sprawdzenie ich efektywności działania po danym okresie użytkowania. Dostępnie dzisiaj metody zapewniają szersze spektrum możliwości oceny biomechanicznej. Niniejsze opracowanie opisuje próbę stworzenia metodyki badań, która pozwoli określić prawidłowe funkcjonowanie sprzętu ortopedycznego na etapie użytkowania.Most of nowadays research focus on effectiveness of the orthopedic equipment. Development of technology and available methods provide wider spectrum of abilities of orthopedic equipment's biomechanical assessment. This paper presents attempt to evolve methods that will allow to determine proper functionality of orthopaedic equipment

Planning of physiotherapeutic procedure in patients after mandible reconstruction taking into account donor site: a literature review

Abstract Background Mandible tumors are very rare. One of the main methods of the treatments is resection of the tumor and then reconstruction of the mandible. The donor site is often distant tissue—fibula or ilium. Following this, it is necessary to improve the patient in two ways, on one hand restoring the function of the mandible, and on the other hand, improving the donor site area. For that reason, physiotherapy after tumor resection and reconstruction of the mandible is very complicated. The aim of this bibliographic review was to find the methods of the reconstruction of the mandible in the context of patients’ functional assessment after surgeries to create effective physiotherapeutic procedures in the feature. Methods PEDro, Medline (PubMed), Cochrane Clinical Trials were searched. Results 767 articles were found. 40 articles were included to this literature review. Conclusions Authors showed different kinds of surgeries strategy for patients with tumors of the mandible. They also showed manners of patients’ functional assessment in the localization of transplantation and donor site. It could be useful for physiotherapists during planning of comprehensive physiotherapy

Phase Transitions and Amorphization of M₂AgF₄ (M = Na, K, Rb) Compounds at High Pressure

We report the results of high-pressure Raman spectroscopy studies of alkali metal fluoroargentates (M2AgF4, where M = Na, K, Rb) combined with theoretical and X-ray diffraction studies for the K member of the series. Theoretical density functional calculations predict two structural phase transitions for K2AgF4: one from low-pressure monoclinic P21/c (beta) phase to intermediate-pressure tetragonal I42d structure at 6 GPa, and another to high-pressure triclinic P1 phase at 58 GPa. However, Raman spectroscopy and X-ray diffraction data indicate that both polymorphic forms of K2AgF4, as well as two other fluoroargentate phases studied here, undergo amorphization at pressures as low as several GPa

Wear Morphology on the Surfaces of CoCrMo Unicompartmental Knee Joint Endoprostheses as Elements of Metal–Metal Friction Nodes

The article assesses the strength and structural parameters of load-bearing layers of metal biobearings made of CoCrMo alloy. The research material consisted of unicompartmental knee joint endoprostheses used in the human body, removed due to excessive wear. No patient participated in the examinations. The endoprostheses used as research material underwent the liquidation procedures in the hospital, which has all necessary permissions and certifications to perform endoprosthetic procedures. Endoprostheses selected for the examinations had been used for 6 to 12 years at similar load conditions as declared by the patients, i.e., body weight of F = 835 N, declared activity expressed as the number of load cycles up to 100 thousand/year, and no artificial joint infections. To assess the homogeneity of the research material, the analysis of chemical composition using a Joel scanning electron microscope with EDS (Energy-dispersive X-ray spectroscopy) was made to exclude endoprostheses with various alloying additives. Microscopic examinations were performed using the Phenom XL microscope, while the wear surface was examined using a Keyence VHX-900F microscope. Several experimental tests were also carried out on load-bearing surfaces to assess changes in strength parameters of the base material after a known life cycle and load conditions. Material hardness using the Vickers method, yield point, critical value of stress intensity coefficient, and the coefficient of friction µ were evaluated. The examinations allowed for the systematization of wear in the knee and femoral components of unicompartmental hip endoprostheses. The statistical evaluation of the number and costs of hip joint replacement surgeries in Poland was also made

Biomechanical analysis of war veteran gait - case analysis

W pracy dokonano oceny biomechanicznej funkcji lokomocyjnych weterana wojennego. Uzyskane dla weterana wojennego wyniki ilościowej analizy chodu porównano z wartościami otrzymanymi dla grupy 56 zdrowych osób dorosłych, bez zaburzeń w obrębie narządu ruchu. Badania doświadczalne przeprowadzono z wykorzystaniem systemu optoelektronicznego BTS Smart. Analizie porównawczej poddano parametry czasowo-przestrzenne i kinematyczne chodu oraz zmiany energii całkowitej, potencjalnej, wypadkowej energii kinetycznej w czasie chodu. Uzyskane dla weterana wojennego wyniki znacznie odbiegały od wartości/zakresów normatywnych, wskazując na znaczne obrażenia aparatu ruch, które poniósł podczas wybuchu improwizowanego urządzenia wybuchowego.In the work the biomechanical evaluation of locomotion functions of a war veteran was made. The results of the quantitative gait analysis obtained for a war veteran were compared with the values obtained for a group of 56 healthy adults without locomotor disorders. Experimental studies were carried out using the BTS Smart optoelectronic system. The spatiotemporal and kinematic parameters of gait as well as changes in total energy, potential energy, kinetic energy and its components during gait were subjected to comparative analysis. The results obtained for a war veteran differed significantly from normative values / ranges, indicating significant injuries to the apparatus, which he suffered during the explosion of the improvised explosive device

Mechanical, Chemical, and Processing Properties of Specimens Manufactured from Poly-Ether-Ether-Ketone (PEEK) Using 3D Printing

As part of the experiments herein, the mechanical properties of specimens made of poly-ether-ether-ketone (PEEK) material using 3D printing technology were determined. Two populations of specimens were investigated, the first of which contained an amorphous structure, while the other held a crystal structure. The studies also investigated the influence of the print directionality on the mechanical properties obtained. Static tensile, three-point bending, and impact tests were carried out. The results for the effect of the structure type on the tensile properties showed that the modulus of elasticity was approximately 20% higher for the crystal than for the amorphous PEEK form. The Poisson’s ratios were similar, but the ratio was slightly higher for the amorphous samples than the crystalline ones. Furthermore, the studies included a chemical PEEK modification to increase the hydrophilicity. For this purpose, nitrite and hydroxyl groups were introduced into the chain by chemical reactions. The results demonstrate that the modified PEEK specimens had worse thermoplastic properties than the unmodified specimens

Evaluation of the impact of decellularization and sterilization on tensile strength transgenic porcinedermal dressings

The aim of this paper was to evaluate which method of acellularization and sterilization is optimal, in the meaning of which processes have the least impact on the deterioration of mechanical properties of porcine tissues used for xenogeneic applications. Methods: The static tensile probe was conducted for 80 skin specimens obtained from transgenic swine, which are used as a wound dressing for skin recipient. Obtained data were subsequently analyzed with the use of statistical methods. Results: It was found that Young’s modulus for the samples after the sterilization process for the dispase substance and the mixed method (SDS + trypsin) were statistically significantly changed. In the case of dispase, Young’s modulus value before the sterilization process was 12.4 MPa and after the value increased to 28.0 MPa. For the mixed method (SDS + trypsin) before the sterilization process Young’s modulus value was 5.6 MPa and after it was increased to 6.3 MPa. The mixed method (SDS + trypsin) had the slightest effect on changing the mechanical properties of the samples before and after the sterilization process. Conclusions: It was confirmed that different methods of acellularization and the process of sterilization have an influence on the change of mechanical properties of the skin of transgenic swine. In the authors’ opinion, the mixed method (SDS + trypsin) should be recommended as the best one for the preparation of transgenic porcine dermal dressings because it ensures a smaller probability of dressing’s damage during a surgical procedure