New nanostructured apatite-type (Na+,Zn2+,CO32-)-doped calcium phosphates : Preparation, mechanical properties and antibacterial activity. - In: Journal of molecular structure, ISSN 0022-2860, Bd. 1222 (2020), 128932
Im Titel sind "+", "2+" und "2-" hochgestellt, "3" tiefgestellt
Nanoparticles with the sizes in the range (20-30) nm of apatite-type Na+,Zn2+,CO32--doped calcium phosphates were prepared from aqueous solution of Na+-Ca2+-Zn2+-NO3--CO32--PO43- system at molar ratios Ca2+/PO43- =1.67, CО32-/РО43- = 1, Zn2+:Ca2+ = 1:100 or 2:100. The elemental analysis showed growth of Zn2+ content in composition of samples from 0.61 to 1.95 wt% at increasing of Zn2+ amount in an initial solution. According to FTIR and Raman data, B-type substitution of PO43- by CO32- realized in apatite-type calcium phosphates. The mechanical properties study for prepared phases showed the dependence of Young's modulus and compressive strength on Zn2+ amount in their composition. Growth of S. epidermidis after the contact with synthesized apatite containing Na+ (0.25 wt%), Zn2+ (0.61 wt%) and CO32- (1.18 wt%) was significantly delayed with an extension of lag time from 1 to 13-14 h. The prepared sample can be considered as a new prospective biomaterial with antibacterial potential.
https://doi.org/10.1016/j.molstruc.2020.128932
ROS-generation and cellular uptake behavior of amino-silica nanoparticles arisen from their uploading by both iron-oxides and hexamolybdenum clusters. - In: Materials science & engineering, ISSN 1873-0191, Bd. 117 (2020), 111305
The present work introduces combination of superparamagnetic iron oxides (SPIONs) and hexamolybdenum cluster ([{Mo6I8}I6]2−) units within amino-decorated silica nanoparticles (SNs) as promising design of the hybrid SNs as efficient cellular contrast and therapeutic agents. The heating generated by SNs doped with SPIONs (Fe3O4SNs) under alternating magnetic field is characterized by high specific absorption rate (SAR = 446 W/g). The cluster units deposition onto both Fe3O4@SNs and “empty” silica nanoparticles (SNs) results in Fe3O4@SNs[{Mo6I8}I6] and SNs[{Mo6I8}I6] with red cluster-centered luminescence and ability to generate reactive oxygen species (ROS) under the irradiation. The monitoring of spin-trapped ROS by ESR spectroscopy technique indicates that the ROS-generation decreases in time for SNs[{Mo6I8}I6] and [{Mo6I8}I6]2− in aqueous solutions, while it remains constant for Fe3O4@SNs[{Mo6I8}I6]. The cytotoxicity is low for both Fe3O4@SNs[{Mo6I8}I6] and SNs[{Mo6I8}I6], while the flow cytometry indicates preferable cellular uptake of the former versus the latter type of the nanoparticles. Moreover, entering into nucleus along with cytoplasm differentiates the intracellular distribution of Fe3O4@SNs[{Mo6I8}I6] from that of SNs[{Mo6I8}I6], which remain in the cell cytoplasm only. The exceptional behavior of Fe3O4@SNs[{Mo6I8}I6] is explained by residual amounts of iron ions at the silica surface.
https://doi.org/10.1016/j.msec.2020.111305
Polyimide@Ketjenblack composite: a porous organic cathode for fast rechargeable potassium-ion batteries. - In: Small, ISSN 1613-6829, Bd. 16 (2020), 38, 2002953, insges. 8 S.
Potassium-ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium-ion batteries. Here, a porous organic PolyimideKetjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g^-1 at 100 mA g^-1), high rate capability (125 and 105 mAh g^-1 at 1000 and 5000 mA g^-1), and long cycling stability (76% capacity retention at 2000 mA g^-1 over 1000 cycles). The domination of fast capacitive-like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization. Moreover, a renewable and low-cost full cell is demonstrated with superior rate behavior (106 mAh g^-1 at 3200 mA g^-1). This work proposes a strategy to design polymer electrodes for high-performance organic PIBs.
https://doi.org/10.1002/smll.202002953
Influence of lens fluorescence on fluorescence lifetime imaging ophthalmoscopy (FLIO) fundus imaging and strategies for its compensation. - In: Translational Vision Science & Technology, ISSN 2164-2591, Bd. 9 (2020), 8, 13, S. 1-10
https://doi.org/10.1167/tvst.9.8.13
Influence of thermal treatment on the magnetic properties and morphology of electrodeposited Fe-Co films. - In: Journal of magnetism and magnetic materials, ISSN 1873-4766, Bd. 513 (2020), 167204
Fe-Co films were prepared by electrodeposition from an electrolyte containing citric acid and annealed afterwards at different temperatures up to 700 ˚C. The grain sizes of the deposits increased from 11 nm to 30 nm with increasing annealing temperature, which lead to changes in magnetic properties of deposits. SQUID measurements indicate that there is a difference between the coercive force, Hc, of the as deposited samples (17 Oe) and the heat-treated samples (25-40 Oe) with a measurement error of 1-2 Oe. The remnant magnetization, Mr, decreased from 190 ± 12 emu/cm^3 for the as deposited to 75 ± 5 emu/cm^3 for the annealed samples, respectively. The saturation magnetization, Ms, seems not to be influenced strongly by the thermal treatment, with the only exception for the samples annealed at 500 ˚C. Thus, Ms has a slightly decreasing tendency from 1880 ± 90 emu/cm^3 for the as-deposited samples to 1780 ± 85 emu/cm^3 for samples annealed at 700 ˚C. The biggest value for Ms (2100 ± 105 emu/cm^3) was obtained if the samples were annealed at 500 ˚C. The thermal treatment generated cracks in the deposits. Interestingly, these cracks had a regular rectangular shape only if the deposits were annealed at 600 ˚C. The coercivity of the layers annealed at 600 ˚C was lower compared to layers annealed at the other temperatures. Magnetic force microscopy measurements indicated the magnetic domain distribution and the topography of the annealed deposits. The deposits showed the best soft magnetic properties if annealed between 500 and 600 ˚C.
https://doi.org/10.1016/j.jmmm.2020.167204
NiCo2O4Ni2P nanorods grown on nickel nanorod arrays as a bifunctional catalyst for efficient overall water splitting. - In: Materials today, ISSN 2468-6069, Bd. 17 (2020), 100490
The development of efficient and durable non-noble metal catalysts remains a challenge in electrocatalytic water splitting applications. To address this, a bifunctional catalyst involving hierarchical NiCo2O4Ni2P nanorods grown on nickel nanorod arrays (NiCo2O4@Ni2P/NAs) was designed and fabricated in this study for overall water splitting that provided high activity and acceptable stability. And if used as the cathode and anode in alkaline media, the NiCo2O4@Ni2P/NAs only required 1.58 V to achieve a current density of 10 mA cm^-2, which is superior to most reported catalysts and can be attributed to a unique core-shell structure and coexisting crystalline/amorphous Ni2P phases.
https://doi.org/10.1016/j.mtener.2020.100490
Molten iodide salt electrolyte for low-temperature low-cost sodium-based liquid metal battery. - In: Journal of power sources, ISSN 1873-2755, Bd. 475 (2020), 228674
Using low-melting-point electrolytes could overcome various key challenges of low-cost sodium-based liquid metal batteries (Na-LMBs), e.g. high rates of self-discharge and degradation of structural materials, by lowering their operating temperatures. Molten halide salts are considered promising electrolyte candidates for Na-LMBs due to their high stability and electrical conductivity. In this work, thermodynamic simulation via FactSageTM and thermal analysis via e.g. Differential Scanning Calorimeter (DSC) were carried out to explore the NaI-LiI-KI system, since it could be a promising electrolyte for Na-LMBs due to its low melting point and Na solubility. The results show that the eutectic NaI-LiI-KI performs as a pseudo-binary salt with a melting point of ˜290 ˚C. In this pseudo-binary salt, the solubility of NaI in the eutectic LiI-KI is ˜7 mol%. Using the eutectic NaI-LiI-KI electrolyte, Na-LMBs could be operated at < 350 ˚C. Moreover, the Na solubility and Na+ conductivity of the eutectic NaI-LiI-KI electrolyte, which are vital to the battery performance, were estimated by calculation based on the literature data. Additionally, its applicability and economy were also discussed based on cost pre-analysis of salt materials, salt treatment and structural materials regarding salt corrosivity.
https://doi.org/10.1016/j.jpowsour.2020.228674
Cation exchange behavior during the redox switching of poly (3,4-ethylenedioxythiophene) films. - In: Journal of solid state electrochemistry, ISSN 1433-0768, Bd. 24 (2020), 11/12, S. 3231-3244
Poly (3,4-ethylenedioxythiophene), PEDOT, films were synthesized at room temperature by potentiodynamic and potentiostatic step deposition in aqueous solutions containing EDOT monomer and LiClO4. In some solutions, the effect of small amounts of sodium dodecylsulfate, SDS, on the polymerization rate of EDOT and on the stiffness of the obtained PEDOT film was studied. The obtained PEDOT films were transferred in aqueous solutions containing cations with different molar mass, such as H+, Li+, Na+, K+, and Cs+. The apparent molar masses of the exchanged species during potentiodynamic experiments were determined by in situ microgravimetry. These measurements underlined the importance of the electrolyte chosen for electropolymerization process. It is known that SDS anions can be trapped inside the polymer layer during electropolymerization, providing them with a cation exchange behavior. However, even if the PEDOT films were deposited from an electrolyte without SDS, they still acted as cation exchangers.
https://doi.org/10.1007/s10008-020-04809-6
Electrocodeposition of titanium and gallium from 1-butyl-1-methylpyrrolidiniumtrifluoromethanesulfonate. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Volume 167 (2020), number 12, 122512
Electrochemical co-deposition of gallium and titanium on copper and gold substrates from the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate was investigated in the temperature range from 25 ˚C to 140 ˚C. Crystalline gallium-titanium alloys were obtained by annealing the deposits at 800 ˚C for 16 h. X-ray diffraction performed on the annealed specimens confirmed the formation of crystalline phases. In situ quartz crystal microbalance experiments gave further insight into the initial stages of gallium-titanium co-deposition. One can tune the composition of the films by changing the deposition potential or the deposition technique. Gallium rich films with more than 60 wt% were obtained by potentiostatic depositions at 140 ˚C. We could show that no elemental titanium can be electrodeposited from bis(cyclopentadienyl)titanium(IV) bis(trifluoromethanesulfonate) in 1-butyl-1-methyl- pyrrolidinium trifluoromethanesulfonate. The addition of GaCl 3 to the electrolyte facilitated the reduction of Ti(IV) species.
https://doi.org/10.1149/1945-7111/abb27f
Numerical simulation of copper deposition in the Hull cell based on Butler-Volmer kinetics. - In: Journal of the Electrochemical Society, ISSN 1945-7111, Volume 167 (2020), number 12, 122506
In industry plating baths are often characterized by visual evaluation of a Hull cell deposition. In an academic approach, kinetic parameters are determined with cyclic voltammetry to obtain a deeper understanding of reaction mechanisms. In this paper we combine both approaches and show how via numerical simulations based on the boundary element method kinetic parameters can be extracted from Hull cell experiments. This combined method enables a better understanding of industrial electroplating processes without losing important information about coating and visual appearance. The validation is done in an acidic copper system using the kinetic parameters obtained from cyclic voltammetry for simulating the current density distribution and the cell voltage of a Hull cell deposition, followed by a comparison with experimental data. As an additional insight obtained from this study, the presence of O2 lowers the anodic transfer coefficient, while Cl- ions in the electrolyte increase the exchange current density.
https://doi.org/10.1149/1945-7111/abb1d5