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- ItemSol gel synthesis of TiO2@ZnO composites for self-cleaning and antimicrobial coating(IOP Publishing, 2024-07-23) Bruzl, Dominik; Bocian, Luboš; Sokola, Patrik; Másilko, Jiří; Sedlačík, Martin; Švec, Jiří; Bartoníčková, Eva; Šoukal, FrantišekIn recent years, the development of advanced materials for applications in self-cleaning surfaces and antimicrobial coatings has received considerable attention due to its potential impact on environmental sustainability and public health. Among the emerging materials, metal oxide-based photocatalysts have shown promise in addressing these challenges. In this context, the present study focuses on the promise sol-gel synthesis and potential photocatalytic properties of TiO2@ZnO (x = 0.6 - 0.9) nano-scaled particles, with particular emphasis on their applications in self-cleaning and microbial coatings. The choice of TiO2@ZnO (x = 0.6 - 0.9) as the subject of investigation is driven by the advantageous properties of both titanium dioxide (TiO2) and zinc oxide (ZnO). TiO2 is known for its exceptional photocatalytic activity, while ZnO is known for its antimicrobial properties. By combining these two metal oxides in a controlled manner, we aim to harness their synergistic effects to create a multifunctional material with enhanced performance. A titanium (IV) isopropoxide and zinc acetate dihydrate have been used as precursors for the so-gel process. The synthesised powders were evaluated by X-ray diffraction analysis and Raman spectroscopy to determine the allotropy of TiO2 and possible lattice distortions. The optical band gap (Egap) was evaluated by molecular reflection UV-VIS spectroscopy. In addition, size and morphology were determined by scanning electron microscopy (SEM).
- ItemBiaxial porosity gradient and cell size adjustment improve energy absorption in rigid and flexible 3D-printed reentrant honeycomb auxetic structures(Elsevier, 2024-06-01) Štaffová, Martina; Ondreáš, František; Žídek, Jan; Jančář, Josef; Lepcio, PetrThis paper compares different uniaxial and biaxial graded designs of auxetic reentrant honeycomb structures to enhance their mechanical properties, especially the specific energy absorption under compressive load. The lattice structures were 3D printed using the vat photopolymerization masked-stereolithography technique from two different materials - tough (OR) and flexible (FR). The results were evaluated from a material and structural point of view, investigating the effect of porosity, cell number, size, graded design, and fracture mode. The universally best energy-absorbing performance was found in a biaxially graded structure with a center-wise location of the highest local porosity. Depending on the used resin, its energy absorption capacity was up to 2-3 times enhanced compared to a reference uniform-porosity auxetic design. The presented data constitutes a fundamental understanding of auxetic structures and identifies practical approaches for tuning the auxetic structures' performance regarding their mechanical response. Finally, this study demonstrates the potential of shape versatility offered by 3D printing and other additive manufacturing techniques.
- ItemAntimycotic effects of the plasma gun on the yeast Candida glabrata tested on various surfaces(WILEY-V C H VERLAG GMBH, 2024-07-04) Trebulová, Kristína; Orel, Inna; Pouvesle, Jean Michel; Robert, Eric; Rouillard, Amaury; Stancampiano, Augusto; Hrudka, Jan; Menčík, Přemysl; Kozáková, Zdenka; Měšťánková, Zuzana; Kužmová, Darina; Paličková, Ivana; Čížek, Alois; Krčma, FrantišekThis work focuses on the antimycotic effects of the plasma gun as a potential tool for the treatment of superficial infections. Candida glabrata was chosen as a model microorganism. The preliminary tests have been done on the agar plates to establish the basic plasma parameters. To render this research more appropriate to the real application, more complex inoculation substrates, pork skin and 3D-printed models of the dog ear canal have been used. The results of this work confirm the high efficiency of cold plasma in the inhibition of yeasts on different surfaces and will lead to further experiments.
- ItemEffect of four-component binder on characteristics of self-compacting and fibre-reinforced self-compacting mortars(Springer, 2024-03-26) Rao, Sarella Venkateswara; Palou, Martin; Novotný, Radoslav; Žemlička, Matúš; Čepčianska, Jana; Czirak, PeterThe hydration heat of a four-component binder consisting of Portland cement (CEM I 42.5 R), blast-furnace slag (BFS), metakaolin (MK), and silica fume (SF) was investigated using a conduction calorimeter and thermal analytical method to optimize the material composition of self-compacting mortar (SCM). Then, the influence of material composition with different substitution levels (0, 25, 30, and 35% labelled as SCM100, SCM75, SCM70, and SCM65) on physical and mechanical properties of the mortars with two volumetric binder sand ratios of 1:1 and 1:2 (cement: sand) was evaluated. Furthermore, two mortar compositions comprising SCM75 and sand at 1:1 and 1:2 ratios were used to prepare fibre-reinforced self-compacting mortars in five combinations (0, 0.25, 0.5, 0.75, and 1%) of two fibres (polypropylene-PPF and basalt-BF) at a constant content of 1.00 vol%. The properties of the prepared samples were investigated with respect to the characteristics of self-compactibility and mechanical properties of fresh and hardened states, respectively. The rheology characteristics expressed by slump flow, V-funnel, and T20 were found following the EFNARC guidance. The partial replacement of cement by supplementary cementitious materials has enhanced the performances (compressive and flexural strengths, dynamic modulus of elasticity) of self-compacting mortars from the 7th day through pozzolanic activity. Furthermore, adding fibres has enhanced the DME and microstructure of the self-compacting mortars.
- ItemFormulation of mixture proportions and experimental study of heavyweight self-compacting concrete based on magnetite and barite(Sringer Nature, 2024-07-05) Palou, Martin; Podhorska, Janette; Ju, Mikwan; Park, Kyoungsoo; Čepčianska, Jana; Žemlička, Matúš; Koplík, Jan; Novotný, RadoslavThe present study aims to determine the mix proportion of binder, heavyweight aggregates, water-to-binder ratio, and additives to develop self-compacting concrete with a bulk density higher than 2600 kg m-3. It also aims to evaluate the engineering properties, pore structure, and microstructure of established heavyweight self-compacting concrete. Barite (BA), magnetite (MAG) or their mix (MIX) were used as fillers, while binder was composed of Portland cement, blast furnace slag, metakaolin, and limestone at a ratio of 65:15:5:15. Based on text results of V-funnel, S-Cone diameter and S-Cone time, the proportion mix and binder: filler: binder to cement ration was optimized as follows: 1) BA 1: 3.5: 0.42, 2) MAG 1: 4: 0.42, and 3) MIX 1: 3.75: 0.42 with maximal aggregate size not exceeding 2 mm. Not only the bulk density was influenced by aggregate, but also, the mechanical properties, shrinkage, dynamic modulus of elasticity pore structure, and microstructure were also found to be dependent on fillers.