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Rising amounts of antibiotic residues in wastewater cause serious problems including increased bacterial resistance. Wastewater treatment plants (WWTPs) do not, in the case of new, modern pharmaceuticals, ensure their complete removal. Ciprofloxacin (CIP) is one of many micropollutants that partially pass through WWTPs, implying that its monitoring is essential for the assessment of the water quality. In real sewage systems, the determination of CIP needs to be performed under flowing conditions, which calls for the deployment of inexpensive, robust, and easily integrable approaches such as electrochemical techniques. However, to the best of our knowledge, there is no report on the electrochemical determination of CIP in a flowing matrix. To bridge this gap, we perform here cyclic and square-wave voltametric sensing study of CIP employing boron-doped diamond screen printed electrodes in a custom-made 3D printed flow-through cell to mimic conditions in real sewage systems. An irreversible two-step oxidation of CIP is demonstrated, with the first step providing clear Faradaic response as analytically relevant signal. This response was found to scale with the sample flow rate according to the prediction given by Levich equation. Our work provides an in-depth inspection of the electrochemical response of CIP under controlled-convection conditions, which is an essential prerequisite for monitoring this antibiotic in real flowing sewage systems.

Composite filaments with diameter ∼1.75 mm suitable for fused deposition of ceramics were prepared from commercial hydroxyapatite powders (HAp-0, d50 ≤ 35 μm and HAp-1, d50 ≤ 16 μm) and thermoplastic polymer - polyvinyl alcohol. The filament printability in FDC applicable as specific bone-part replacements, is connected to its mechanical strength and slenderness ratio affecting the resistance to buckling. The HAp content in prepared composite filaments was at the level of ∼ 50 % and their mechanical properties were compared to commercial filament based on polylactic acid and ∼ 27 % of gypsite used as inorganic filler. The tensile strength of laboratory prepared filaments was about 3 times lower than strength found for commercial filament. The critical buckling pressure calculated from Euler buckling analysis using measured intrinsic Young´s modulus revealed underestimated critical pressure values ∼ 2.5–5.0 times if compared to values of maximal filament compressive pressure loads simulating buckling.

Titanium diboride (TiB2) represents a perspective material for innovations in aluminium technology. This refractory ceramic material has superior thermal and electrical conductivity and considerabl...

Among methods covered under the additive manufacturing family, the Fused Filament Fabrication (FFF) is considered one of the most accessible, variable, and cost-effective prototyping techniques for processing polymer and composite materials. In this paper, however, the FFF technique is used to fabricate highly dense alumina parts of different designs (cylinders, bars, and pillars) using a low-cost desktop 3D printer. To investigate the repeatability and reliability of filament-based 3D printing, micro-computed tomography (micro-CT) was applied to analyse and evaluate critical processing steps during the preparation of high dense alumina ceramics. Results of non-destructive testing showed that the 3D sample shape plays a significant role in defect-free printouts, and the printed errors and deviations increased in the direction from cylindrical to prismatic objects. Despite internal cracks, pores and cavities revealed by the micro-CT analysis, sintered objects achieved relative densities of up to 96%.

Since multifunctional transparent titanate ceramics were reported, these materials have become potential materials for electro-optical devices. So far, the applications are limited because the fabrication of transparent titanates involves expensive sintering techniques (e.g., hot iso-pressure sintering, vacuum sintering, and spark plasma sintering). This study modified the SrTiO3 starting powders using the common acids of hydrogen peroxide and acetic acid. Then the dense SrTiO3 specimens were obtained using pressureless sintering. The experimental results show that acetic acid dissolves more Sr in the powder surface to create the amorphous structure, and this Ti-rich amorphous structure provides homogenous liquid phase sintering to increase the grain boundary mobility for the dense SrTiO3.

Fused filament fabrication of ceramic (FFFC) is a promising additive manufacturing (AM) method for production of complex-shaped ceramic bodies. It allows to generate complex structures hardly obtainable by conventional ceramic shaping methods. The thermal processing of ceramic composite objects prepared by the FFFC generates structures with the option to fine-tune the external size of objects after processing by changing the thermal processing temperatures. Higher temperatures lead to higher shrinkage, while maintaining the complex internal structure generated in 3D printing process. Previously published studies concerning ceramic composite filaments often mention requirement of special modification to AM devices such as pre-heating of the feedstock before its entry point into the feeder to avoid mechanical damage. This study investigates internal structure of bodies prepared by FFFC using novel composite filament based on mullite ceramic and the deformation induced by processing of the composite material in the thermal processing stage. Studied in-house developed material is printable using commercial AM devices with no additional modifications of the machines and exhibits no deformations during debinding and sintering, even when using aggressive thermal debinding strategy. The material can be printed using standard 0.4 mm nozzles and does not require use of specialized high temperature furnaces. This qualifies this new composite filament as suitable material for commercial widespread application of FFFC process.

A spray pyrolysis (SP) method for the preparation of Eu-doped gehlenite glassy particles is presented. The phase composition, surface morphology, inner structure and specific surface area of the gehlenite glass particles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption, respectively, and spectrophotometry was used to evaluate the photoluminescence (PL) behavior of the particles. Moreover, the SP morphology formation mechanisms are discussed. Three distinct morphologies, i.e., solid, porous and hollow, were detected , depending on the precursor solution concentration. Combined with the PL result, this study suggests that emission can be enhanced by adjusting the particle morphologies from solid to porous or hollow.

Ytterbium–aluminate glass microspheres with the compositions identical to those of the binary Yb3Al5O12–Al2O3 eutectic (79.4 mol% Al2O3 and 20.6 mol% Yb2O3) and of the ytterbium aluminium garnet (62.5 mol% Al2O3 and 37.5 mol% Yb2O3) were studied. The glasses were prepared in the form of microspheres by flame synthesis from a precursor powders synthesised by Pechini sol–gel method. The microspheres consisted of amorphous ytterbium aluminate matrix containing low amount of crystalline phases, namely ytterbium aluminum garnet (YbAG) and α-Al2O3. The influence of glass structure on optical properties was studied. Absorption peaks characteristic for Yb3+ doped glasses centered at 927, 931 and 975 nm were observed for both studied compositions. In polycrystalline samples prepared by controlled crystallisation of the glasses (6 h at 1200 °C in ambient atmosphere) a shift of absorption peaks was observed, with maxima at 934, 969 and 1029 nm.