In this work, the effect of moderate electromagnetic fields (2.5, 10, and 15 mT) was studied using an immersed coil inserted directly into a bioreactor on batch cultivation of yeast under both aerobic and anaerobic conditions. Throughout the cultivation, parameters, including CO2 levels, O2 saturation, nitrogen consumption, glucose uptake, ethanol production, and yeast growth (using OD 600 measurements at 1-h intervals), were analysed. The results showed that 10 and 15 mT magnetic fields not only statistically significantly boosted and sped up biomass production (by 38-70%), but also accelerated overall metabolism, accelerating glucose, oxygen, and nitrogen consumption, by 1-2 h. The carbon balance analysis revealed an acceleration in ethanol and glycerol production, albeit with final concentrations by 22-28% lower, with a more pronounced effect in aerobic cultivation. These findings suggest that magnetic fields shift the metabolic balance toward biomass formation rather than ethanol production, showcasing their potential to modulate yeast metabolism. Considering coil heating, opting for the 10 mT magnetic field is preferable due to its lower heat generation. In these terms, we propose that magnetic field can be used as novel tool to increase biomass yield and accelerate yeast metabolism.
- Klíčová slova
- Aerobic, Anaerobic, Batch fermentation, Biomass, Magnetic field, Metabolism acceleration, Yeast,
- MeSH
- aerobióza MeSH
- anaerobióza MeSH
- biomasa * MeSH
- bioreaktory mikrobiologie MeSH
- dusík metabolismus MeSH
- ethanol * metabolismus MeSH
- fermentace * MeSH
- glukosa metabolismus MeSH
- glycerol metabolismus MeSH
- kyslík metabolismus MeSH
- magnetické pole * MeSH
- Saccharomyces cerevisiae * metabolismus růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- dusík MeSH
- ethanol * MeSH
- glukosa MeSH
- glycerol MeSH
- kyslík MeSH
In this study, the properties of the natural mineral chalcopyrite CuFeS2 after mechanical activation in a planetary mill were studied. The intensity of mechanical activation was controlled by changing the revolutions of the mill in the range 100-600 min-1. A series of characterization techniques, such as XRD, SEM, TEM, TA (DTA, TG, and DTG), particle size analysis, and UV-vis spectroscopy was applied and reactivity studies were also performed. Several new features were revealed for the mechanically activated chalcopyrite, e.g. the poly-modal distribution of produced nanoparticles on the micrometer scale, agglomeration effects by prolonged milling, possibility to modify the shape of the particles, X-ray amorphization and a shift from a non-cubic (tetragonal) structure to pseudo-cubic structure. The thermoelectric response was evaluated on the "softly" compacted powder via the spark plasma sintering method (very short holding time, low sintering temperature, and moderate pressure) by measuring the Seebeck coefficient and electrical and thermal conductivity above room temperature. The milling process produced samples with lower resistivity compared to the original non-activated sample. The Seebeck data close to zero confirmed the "compensated" character of natural chalcopyrite, reflecting its close-to stoichiometric composition with low concentration of both n- and p-type charge carriers. Alternatively, an evident correlation between thermal conductivity and energy supply by milling was observed with the possibility of band gap manipulation, which is associated with the energy delivered by the milling procedure.
- Publikační typ
- časopisecké články MeSH
Twelve Cu-based ternary (Cu-Me1-S, Me1 = Fe, Sn, or Sb) and quaternary (Cu-Me2-Sn-S, Me2 = Fe, Zn, or V) nanocrystalline sulfides are shown as perspective antibacterial materials here. They were prepared from elemental precursors by a one-step solvent-free mechanochemical synthesis in a 100 g batch using scalable eccentric vibratory ball milling. Most of the products have shown strong antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. For instance, stannite Cu2FeSnS4 and mohite Cu2SnS3 were the most active against E. coli, whereas kesterite Cu2ZnSnS4 and rhodostannite Cu2FeSn3S8 exhibited the highest antibacterial activity against S. aureus. In general, stannite has shown the best antibacterial properties out of all the studied samples. Five out of twelve products have been prepared using mechanochemical synthesis for the first time in a scalable fashion here. The presented synthetic approach is a promising alternative to traditional syntheses of nanomaterials suitable for biological applications and shows ternary and quaternary sulfides as potential candidates for the next-generation antibacterial agents.
- Publikační typ
- časopisecké články MeSH
CdS nanoparticles were successfully synthesized using cadmium acetate and sodium sulfide as Cd and S precursors, respectively. The effect of using sodium thiosulfate as an additional sulfur precursor was also investigated (combined milling). The samples were characterized by XRD, Raman spectroscopy, XPS, UV-Vis spectroscopy, PL spectroscopy, DLS, and TEM. Photocatalytic activities of both CdS samples were compared. The photocatalytic activity of CdS, which is produced by combined milling, was superior to that of CdS, and was obtained by an acetate route in the degradation of Orange II under visible light irradiation. Better results for CdS prepared using a combined approach were also evidenced in photocatalytic experiments on hydrogen generation. The antibacterial potential of mechanochemically prepared CdS nanocrystals was also tested on reference strains of E. coli and S. aureus. Susceptibility tests included a 24-h toxicity test, a disk diffusion assay, and respiration monitoring. Bacterial growth was not completely inhibited by the presence of neither nanomaterial in the growth environment. However, the experiments have confirmed that the nanoparticles have some capability to inhibit bacterial growth during the logarithmic growth phase, with a more substantial effect coming from CdS nanoparticles prepared in the absence of sodium thiosulfate. The present research demonstrated the solvent-free, facile, and sustainable character of mechanochemical synthesis to produce semiconductor nanocrystals with multidisciplinary application.
- Klíčová slova
- antibacterial activity, combined milling, hydrogen evolution, mechanosynthesis, photocatalysis, semiconductor, wastewater treatment,
- Publikační typ
- časopisecké články MeSH
Chalcopyrite CuFeS2 , a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste-free and inexpensive. The synthesized nano-powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS2 powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano-powders are corroborated by the universal evolution of the parameter SBET /X (SBET -specific surface area, X-crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non-doped semiconducting CuFeS2 enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.
- Klíčová slova
- chalcopyrite, energy materials, mechanochemistry, semiconductors, thermoelectrics,
- Publikační typ
- časopisecké články MeSH
A pristine colusite Cu26V2Sn6S32 was successfully synthesised on a 100 g scale via a mechanochemical reaction in an industrial eccentric vibratory ball mill followed by spark plasma sintering (SPS) at 873 K. The milling of elemental precursors from 1 up to 12 hours was performed and the prepared samples were investigated in detail by X-ray powder diffraction, Mössbauer spectroscopy, scanning electron microscopy, and thermoelectric property measurements. The results point to the formation of a high purity and high crystallinity non-exsoluted colusite phase after the SPS process (P4[combining macron]3n, a = 10.7614(1) Å) in the case of a 12 h milled sample. In comparison, samples milled for 1-6 h displayed small quantities of binary Cu-S phases and vanadium core-shell inclusions, leading to a V-poor/Sn-rich colusite with a higher degree of structural disorder. These samples exhibit lower electrical conductivity and Seebeck coefficient while an increase in the total thermal conductivity is observed. This phenomenon is explained by a higher reactivity and grain size reduction upon prolonged milling and by a weak evolution of the chemical composition from a partly disordered V-poor/Sn-rich colusite phase to a well-ordered stoichiometric Cu26V2Sn6S32 colusite, which leads to a decrease in carrier concentration. For all samples, the calculated PF values, around 0.7-0.8 mW m-1 K-2 at 700 K, are comparable to the values previously achieved for mechanochemically synthesised Cu26V2Sn6S32 in laboratory mills. This approach thus serves as an example of scaling-up possibility for sulphur-based TE materials and supports their future large-scale deployment.
- Publikační typ
- časopisecké články MeSH
The wet mechanochemical procedure for the capping of the CdS and CdS/ZnS quantum dot nanocrystals is reported. l-cysteine and polyvinylpyrrolidone (PVP) were used as capping agents. When using l-cysteine, the dissolution of cadmium(II) was almost none for CdS/ZnS nanocrystals. Moreover, prepared CdS- and CdS/ZnS-cysteine nanosuspensions exhibited unimodal particle size distributions with very good stability, which was further supported by the zeta potential measurements. The Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy showed the successful embedment of cysteine into the structure of the nanocrystals. Additionally, the optical properties were examined, and the results showed that the cysteine nanosuspension has promising fluorescence properties. On the other hand, PVP was not determined to be a very suitable capping agent for the present system. In this case, the release of cadmium(II) was higher in comparison to the l-cysteine capped samples. The nanosuspensions were successfully used for in vitro studies on selected cancer cell lines. Using fluorescence microscopy, it was evidenced that the nanocrystals enter the cell and that they can serve as imaging agents in biomedical applications.
- Klíčová slova
- Capping, CdS/ZnS nanocrystals, Mechanochemistry, Polyvinylpyrrolidone, Toxicity, l-cysteine,
- MeSH
- biologický transport MeSH
- Caco-2 buňky MeSH
- cystein chemie MeSH
- difuze MeSH
- fluorescence MeSH
- fluorescenční mikroskopie MeSH
- HCT116 buňky MeSH
- HeLa buňky MeSH
- kinetika MeSH
- kontrastní látky chemie farmakologie MeSH
- kvantové tečky chemie ultrastruktura MeSH
- lidé MeSH
- MFC-7 buňky MeSH
- nanočástice chemie ultrastruktura MeSH
- povidon chemie MeSH
- povrchové vlastnosti MeSH
- sloučeniny kadmia chemie farmakologie MeSH
- sloučeniny zinku chemie farmakologie MeSH
- sulfidy chemie farmakologie MeSH
- suspenze MeSH
- velikost částic MeSH
- viabilita buněk účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cadmium sulfide MeSH Prohlížeč
- cystein MeSH
- kontrastní látky MeSH
- povidon MeSH
- sloučeniny kadmia MeSH
- sloučeniny zinku MeSH
- sulfidy MeSH
- suspenze MeSH
- zinc sulfide MeSH Prohlížeč
