Pokročilé keramické materiály

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Adaptability of Electrospun PVDF Nanofibers in Bone Tissue Engineering
(MDPI, 2025-01-25) Havlíková, Tereza; Papež, Nikola; Fohlerová, Zdenka; Kaspar, Pavel; Dallaev, Rashid; Částková, Klára; Ţălu, Ştefan
This study focused on the development of a suitable synthetic polymer scaffold for bone tissue engineering applications within the biomedical field. The investigation centered on electrospun polyvinylidene fluoride (PVDF) nanofibers, examining their intrinsic properties and biocompatibility with the human osteosarcoma cell line Saos-2. The influence of oxygen, argon, or combined plasma treatment on the scaffold’s characteristics was explored. A comprehensive design strategy is outlined for the fabrication of a suitable PVDF scaffold, encompassing the optimization of electrospinning parameters with rotating collector and plasma etching conditions to facilitate a subsequent osteoblast cell culture. The proposed methodology involves the fabrication of the PVDF tissue scaffold, followed by a rigorous series of fundamental analyses encompassing the structural integrity, chemical composition, wettability, crystalline phase content, and cell adhesion properties.
Unveiling Magnetic Characteristics of (CoCrFeNiMn)₃O₄ High-Entropy Oxide: The Role of Compositional Optimization
(AMER CHEMICAL SOC, 2025-05-22) Daradkeh, Samer Issa Abdel Razzaq; Allaham, Mohammad Mahmoud Mohammad; Spusta, Tomáš; Pouchlý, Václav; Knápek, Alexandr; Tofel, Pavel; Sobola, Dinara
High-entropy oxides (HEOs) are considered promising materials in many electrical applications, especially in the fields of batteries, energy storage and conversion, and catalysis. The study material, (CoCrFeNiMn)3O4 in particular, has been shown to possess gigantic capacitance, a characteristic that emanates from its oxide precursors properties. The material was successfully prepared using the solid-state reaction method, as the material showed structural stability despite its different composition and the possibility of controlling its magnetic properties based on its composition, as the saturation value of Fe excessive addition-S2.Fe reached 52 emu/g, with it having a relatively high coercivity value, which is estimated at 1102.47 Oe. It was also observed that electron hopping between different oxidation states is based on the high-resolution X-ray photoelectron spectroscopy (XPS) results, which has a role in the magnetic properties.
Piezophotocatalytic Activity of PVDF/Fe3O4 Nanofibers: Effect of Ultrasound Frequency and Light Source on the Decomposition of Methylene Blue
(ACS Publications, 2025-05-29) Rabadanova, Alina; Selimov, Daud; Gulakhmedov, Rashid; Magomedova, Asiyat; Ronoh, Kipkurui; Částková, Klára; Sobola, Dinara; Kaspar, Pavel; Shuaibov, Abdulatip; Abdurakhmanov, Magomed; Kh. Rabadanov, Murtazali; Ramazanov, Shikhgasan; Orudzhev, Farid
This study investigates the piezophotocatalytic (PPhC) performance of electrospun nanofibrous membranes composed of polyvinylidene fluoride (PVDF) and magnetite (Fe3O4) nanoparticles. The composite membranes were synthesized via electrospinning, with optimized parameters to promote -phase crystallinity and uniform fiber morphology. Structural and phase analyses by SEM, FTIR, Raman, and XPS confirmed the predominance of the electroactive -phase (99.8%) in the composite, as well as strong interfacial interaction between Fe3O4 and the PVDF matrix. The composites exhibited significantly enhanced surface hydrophilicity and piezoelectric response compared to pristine PVDF. The piezoelectric potential generation was confirmed using a flexible piezoelectric nanogenerator (PENG), where a 3 × 1 cm membrane generated output voltages up to 2 V under periodic mechanical deformation at 4 Hz. Photocatalytic and piezophotocatalytic degradation of methylene blue (MB) was carried out under UV and visible light at varying ultrasonic frequencies. Maximum PPhC efficiency was achieved at 40 kHz, with 93% dye degradation in 60 min and a reaction rate constant exceeding the sum of photocatalysis and piezocatalysis by 13%, indicating a pronounced synergistic effect. Reactive oxygen species trapping and fluorescence spectroscopy confirmed •OH as the dominant oxidant. H2O2 productivity under PPhC reached 1700 mol·g–1·h–1 in pure water, with a light-to-chemical energy conversion efficiency of 0.26%. Additionally, experiments conducted under an alternating magnetic field (0.3 T, 1.3 Hz) demonstrated 50% MB degradation within 240 min, revealing the contribution of magnetoelectric coupling as an alternative catalytic activation mechanism. The results suggest that PVDF/Fe3O4 nanocomposites are highly promising for multifunctional catalytic applications, combining piezoelectric, photo-, and magnetoelectric activation for efficient water purification and green oxidant production.
Correlation of Dielectric Properties and Vibrational Spectra of Composite PVDF/Salt Fibers
(MDPI, 2024-08-26) Dallaev, Rashid; Sarkar, Ranjini; Selimov, Daud; Papež, Nikola; Kočková, Pavla; Schubert, Richard; Částková, Klára; Orudzhev, Farid; Ramazanov, Shihgasan; Holcman, Vladimír
Nitride salts were added to polyvinylidene fluoride fibers and then the fiber mats were prepared by electrospinning. An experimental investigation of the structure was provided by Raman, FTIR, SEM, and XRD. The phase ratio of the polymer was studied both theoretically and experimentally in connection with the addition of the hydrates Mg(NO3)2, Ca(NO3)2, and Zn(NO3)2 salts. The com-parison of simulated and experimental data for vibrational spectroscopies is discussed. We provide a comparison of triboelectric, dielectric, and compositional characterization of PVDF fibers doped with three types of nitride hydrates. Doping of PVDF fibers with magnesium nitrate hexahydrate leads to significant improvement of the triboelectric performance.
Oxidation Behavior and Outward Diffusion of Al Along Oxide Grain Boundaries of FeCrAl Alloys Overdoped with Zr and Hf
(SPRINGER, 2024-02-01) Daradkeh, Samer Issa Abdel Razzaq; Recalde, Oscar; Mousa, Marwan Suleiman; Sobola, Dinara; Boll, Torben
The formation of the alpha-Al2O3 scale on reactive element (RE)-doped FeCrAl alloys is commonly believed to be primarily caused by inward oxygen transport along grain boundaries. However, this study suggests that metal ion outward diffusion also plays a role in the development of the oxide scales and their microstructural characteristics. The study examines the oxidation behavior and grain boundary outward diffusion of iron-chromium alloys containing similar to 10 at% aluminum and similar to 22 at% chromium, doped with an over-critical concentration of REs, i.e., Zr and Hf. All samples were investigated after thermal exposure at 1100 degrees C by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atom probe tomography (APT). As a result of the overdoping, a considerable increase in oxide growth, an increase in the depth of internal oxidation, and RE-oxide formation near and at oxide grain boundaries (GBs) were observed as a consequence of increased inward and outward diffusion. The effect of overdoping manifests itself differently depending on the RE type and amount due to different solubility, ionic size, and electronic structure of alumina. The sample with Zr retained the adhesion of alumina to the alloy after the first and second thermal exposure, while Hf overdoping resulted in severe spallation after the second thermal exposure.

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