Nowadays, magnetoelectric nanomaterials are on their way to finding wide applications in biomedicine for various cancer and neurological disease treatment, which is mainly restricted by their ...relatively high toxicity and complex synthesis. This study for the first time reports novel magnetoelectric nanocomposites of Cosub.xFesub.3−xOsub.4-BaTiOsub.3 series with tuned magnetic phase structures, which were synthesized via a two-step chemical approach in polyol media. The magnetic Cosub.xFesub.3−xOsub.4 phases with x = 0.0, 0.5, and 1.0 were obtained by thermal decomposition in triethylene glycol media. The magnetoelectric nanocomposites were synthesized by the decomposition of barium titanate precursors in the presence of a magnetic phase under solvothermal conditions and subsequent annealing at 700 °C. X-ray diffraction revealed the presence of both spinel and perovskite phases after annealing with average crystallite sizes in the range of 9.0-14.5 nm. Transmission electron microscopy data showed two-phase composite nanostructures consisting of ferrites and barium titanate. The presence of interfacial connections between magnetic and ferroelectric phases was confirmed by high-resolution transmission electron microscopy. Magnetization data showed expected ferrimagnetic behavior and σsub.s decrease after the nanocomposite formation. Magnetoelectric coefficient measurements after the annealing showed non-linear change with a maximum of 89 mV/cm*Oe with x = 0.5, 74 mV/cm*Oe with x = 0, and a minimum of 50 mV/cm*Oe with x = 0.0 core composition, that corresponds with the coercive force of the nanocomposites: 240 Oe, 89 Oe and 36 Oe, respectively. The obtained nanocomposites show low toxicity in the whole studied concentration range of 25-400 μg/mL on CT-26 cancer cells. The synthesized nanocomposites show low cytotoxicity and high magnetoelectric effects, therefore they can find wide applications in biomedicine.
Ultrathin porous Cosub.3Osub.4 nanosheets are synthesized successfully, the thickness of which is about three unit-cell dimensions. The enhanced oxygen evolution reaction (OER) performance and ...electronic interaction between Cosub.3Osub.4 and Au is firstly reported in Cosub.3Osub.4 ultrathin porous nanosheets by physically mixing with Au nanoparticles. With the loading of the Au nanoparticles, the current density of ultrathin porous Cosub.3Osub.4 nanosheets is enhanced from 9.97 to 14.76 mA cmsup.−2 at an overpotential of 0.5 V, and the overpotential required for 10 mA cmsup.−2 decreases from 0.51 to 0.46 V, smaller than that of commercial IrOsub.2 (0.54 V). Furthermore, a smaller Tafel slope and excellent durability are also obtained. Raman spectra, XPS measurement, and X-ray absorption near edge structure spectra (XANES) show that the enhanced OER ascribed to a higher Cosup.2+/Cosup.3+ ratio and quicker charge transfer due to the electronic interaction between Au and ultrathin Cosub.3Osub.4 nanosheets with low-coordinated surface, and Cosup.2+ ions are beneficial for the formation of CoOOH active sites.
It is shown for the first time that Co subnanometer coatings deposited by molecular-beam epitaxy on the (0001) surface of the topological insulator BiSbTeSe.sub.2 at a temperature of 330°C open an ...energy gap in the spectrum of topological surface states in the region of the Dirac point with a shift of the Dirac-point position caused by the preliminary deposition of an adsorbate at room temperature. The gap width is 21 ± 6 meV. Temperature-dependent measurements in the range of 15-150 K show no changes in the energy-gap width.
The electrodeposition method was used to obtain nanostructured layers of Co/nano-CeOsub.2 on 304L stainless steel, from a cobalt electrolyte in which different concentrations of CeOsub.2 ...nanoparticles (0, 10, 20, and 30 g/L) were dispersed. The electrodeposition was performed at room temperature using three current densities (23, 48, and 72 mA cmsup.−2), and the time was kept constant at 90 min. The influence of current densities and nanoparticle concentrations on the characteristics of the obtained nanostructured layers is also discussed. An X-ray diffractometer (XRD) was used to investigate the phase structure and cobalt crystallite size of the nanostructured layers, and a contact angle (sessile drop method) was used to assess the wettability of the electrodeposited layers. The roughness of the surfaces was also studied. The results show that the nanostructured layers became more hydrophilic with increasing nanoparticle concentration and increasing current density. In the case of pure cobalt deposits, an increase in the current density led to an increase in the size of the cobalt crystallites in the electrodeposited layer, while for the Co/nano-CeOsub.2 nanostructured layers, the size of the crystallites decreased with increasing current density. This confirms the nanostructuring effect of nano-CeOsub.2 electrocodeposited with cobalt.
Nanosized cobalt aluminate (CoAl.sub.2O.sub.4) was prepared by thermolysis of heteronuclear coordination compound, namely Al.sub.2Co(C.sub.2O.sub.4).sub.4(OH.sub.2).sub.6. The synthesized precursor ...was characterized by chemical analysis, vibrational spectra and thermal analysis. The cobalt aluminate obtained after a heating treatment of the precursor at 700 °C was characterized by IR, XRD, TEM coupled with SAED measurements. Two types of carbon-based electrodes, glassy carbon and boron-doped diamond electrodes were decorated with the obtained cobalt aluminate in order to enhance the electroanalytical performance for the tetracycline (TC) detection in the aqueous solutions. Cyclic voltammetry technique was used to determine the effect of the nanosized CoAl.sub.2O.sub.4 on the electrochemical oxidation of TC and as consequence, for TC detection at both carbon-based electrodes. The obtained cobalt aluminate exhibited the electrocatalytic activity toward TC detection in direct relation with the type of the carbon substrate, which allowed enhancing the electroanalytical parameters of TC detection in the aqueous solution.
Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120°C) and non-hydrothermal (room temperature) from various cobalt sources and 2-methylimidazolate (Hmim) in aqueous solution ...within 30min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co2+ molar ratios and experimental condition. Using Co(NO3)2 as cobalt source, small-sized ZIF-67 crystals with agglomeration were formed. For CoCl2, small-sized rhombic dodecahedron were obtained. While large-sized crystals of rhombic dodecahedron structure were obtained from CoSO4 and Co(OAc)2. Under hydrothermal condition, the size of ZIF-67 crystals tended to be more uniform and the morphology were more regular comparing to non-hydrothermal condition. This study provides a simple way to control the size and morphology of ZIF-67 crystals prepared in aqueous solution.
Zeolitic imidazolate frameworks ZIF-67 were prepared under hydrothermal (120°C) and non-hydrothermal (room temperature) from four different cobalt sources (Co(NO3)2, CoCl2, CoSO4 and Co(OAc)2) in aqueous solution within 30min. The particle size and morphology were found to be related to the reactivity of the cobalt salt, Hmim/Co2+ molar ratios and experimental condition.
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•The particle size and morphology were determined by the reactivity of cobalt salt.•ZIF-67 could be prepared from CoSO4 and Co(OAc)2 at Hmim/Co2+ molar ratio of 10.•Uniform and regular particles were obtained under hydrothermal condition.
Structural features and magnetic behaviour of TbPc sub(2) thin films sublimated on LSMO and on cobalt surfaces have been investigated by synchrotron-based XNLD and XMCD techniques. Different ...orientation of the molecules is observed for the two substrates. No significant magnetic interaction with the ferromagnetic substrates is detected.
Abstract
Bei der Produktion von Lithiumakkumulatoren stellt die Aufbereitung der erforderlichen Rohstoffe höchste Qualitätsanforderungen – und zwar an der Grenze des technisch Machbaren. So sind bei ...den Kathodenmassen z. B. Kontaminationen durch Fremdionen, insbesondere durch Eisen, unbedingt zu vermeiden. Lödige begegnet dieser anspruchsvollen prozesstechnischen Aufgabe mit einer speziellen Ausführung des bewährten Pflugschar‐Mischers, von der in den letzten fünf Jahren bereits über 200 Maschinen weltweit verkauft wurden.
Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human ...carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity.
•Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells.•Soluble cobalt induces more cytotoxicity compared to particulate cobalt.•Soluble and particulate cobalt induce similar levels of genotoxicity.•Particle-cell contact is required for particulate cobalt-induced toxicity.
Co-doped BaCe0.85Tb0.05Co0.1O3aI' (BCTCo) nanopowder was synthesized via a sol-gel method using ethylenediaminetetraacetic acid (EDTA) and citric acid as the chelating agents. Using the resultant ...powder, BCTCo perovskite hollow fibre membranes were then fabricated by the combined phase inversion and sintering technique. Properties of the BCTCo powder and the hollow fibre membranes in terms of crystalline phase, morphology, electrical conductivity, porosity, mechanical strength and hydrogen/oxygen permeation were investigated by a variety of characterization methods. The results indicated that doping of cobalt in the BCTb oxide led to a higher electrical conductivity and lower calcination temperature for the powder precursor to a perovskite structure as well as sintering temperature for the hollow fibre precursors to gastight membranes. In order to obtain gastight and robust hollow fibre membranes, the sintering temperature should be controlled between 1300 and 1450 degree C. The maximum hydrogen flux through the BCTCo hollow fibre membranes reached up to 0.385 mL cm-2 mina1 at 1000 degree C under 50% H2aHe/N2 gradient, which is higher than that of the un-doped BCTb hollow fibre membranes with the same effective thickness, and especially much higher than that obtained from other proton conductors due to the asymmetric structure of the membrane designed. Moreover, the BCTCo hollow fibre membrane also exhibited noticeable oxygen permeation fluxes, i.e. 0.122 mL cm-2 mina1 at 1000 degree C under the air/He gradient. However, doping of cobalt might damage the mechanical stability of the perovskite membranes in the hydrogen-containing atmosphere.
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