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Bottom-up assembly of nanomaterials using solution-processed methods is ideally suited for use in fabrication of large-area optoelectronic devices. Tailorable visible and near-infrared absorption in shaped nanostructured noble metals is strongly influenced by localized plasmon resonance effects. Obtaining sharp and selective absorption with solution-processed methods is a challenge and requires suitable control on the growth kinetics, which ultimately results in appropriate size and morphology of the final product. In this work, a photo-assisted multigenerational growth process for synthesis of silver nanotriangle ink with narrow linewidth absorbance is developed. This technique combines photochemical and seed-mediated growth approaches. The resulting ink exhibits a sharp absorption at 700 nm with full width at half maximum of ∼170 nm, verified by absorption as well as dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy measurements. Numerical modeling using finite-difference time-domain calculations yields a close match with observed absorption and is used to examine electric field distribution and enhancement factor resonating at 720 nm. The synthesis technique is potentially useable for production of highly selective absorbers in solution phase.
In the present work, mechanical, tribological, and electrochemical behaviors of Al Alloy 6061–(0–10) % B4C–(0.25–1.2) % graphene nanoplatelets (GNPs) composites, prepared by a combination of solution mixing and powder metallurgy, were investigated. Properties such as hardness, compressive strength, wear rates, and coefficient of friction (COF) were used to investigate the effects of GNPs on mechanical and self-lubricating tribological behavior. The corrosion resistance of composites was investigated using potentiodynamic polarization and electrochemical impedance techniques. Scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and EDS mapping were employed to study the distribution, the fracture profile, and wear mechanism. The AA 6061–10% B4C–0.6% GNPs composites exhibited sharp increase in hardness and compressive strength and significant decrease in wear rates and COF. However, for GNPs contents exceeding over 0.6 wt%, mechanical properties and wear performances deteriorated. Pulling out of sheared pultruded GNPs was observed during the fracture of composites. Worn surfaces of GNPs-containing composites showed the smeared graphene layer with some macro-cracks exhibiting delamination wear. It was found that the corrosion inhibition efficiency of GNPs was more pronounced in H3BO3 environment than in NaCl solution.
The microstructure of carbon quantum dots (CQDs) has a great influence on their fluorescence properties. Here, different microstructures of CQDs were synthesized by the selective oxidation of graphitized activated carbon using HNO3/HClO4 as the oxidant. We characterized the microstructure and surface chemistry of the CQDs, and the results show that the degree of graphitization of activated carbon has a significant effect on the structure and fluorescence properties of the obtained CQDs. The fluorescence of the CQD solution can be tuned from yellow to green by regulating the degree of graphitization of the activated carbon by heat treatment at high temperature (up to 2500 °C). Moreover, the increased degree of graphitization of the raw carbon precursor is beneficial for significantly reducing the fluorescence self-absorption quenching of the concentrated CQD solution. Importantly, the as-prepared CQDs have no cytotoxicity and can be used as bioimaging agents.
We herein report the detection of folic acid (FA) via the fluorometric method using water-soluble AgInS2 quantum dots (QDs). The optical analysis showed that the addition of FA to AgInS2 QDs results in significant, blue-shifted photoluminescence emission. A linear plot of the blueshift in the photoluminescence wavelength position against FA concentration was obtained in the range of 0.03–33 µM with the detection limit of 52 nM. Interference study showed the selective detection of FA in the presence of other biomolecules. The as-synthesized AgInS2 QDs can be employed as an optical sensor for the rapid detection of FA in aqueous solutions.
We apply the first-principles calculations to investigate the structure, mechanical, and thermodynamic properties of WB12 and TiB12 under high pressure (0–100 GPa). The calculated results show that WB12 and TiB12 are thermodynamically stable at the 0 GPa or high pressure. WB12 is more thermodynamically stable than TiB12. In particular, the calculated Vickers hardness of WB12 and TiB12 at the ground state is 29.9 GPa and 43.2 GPa, respectively, indicating that TiB12 is a potential superhard material. With increasing pressure, the calculated elastic modulus of WB12 and TiB12 increases gradually. The calculated electronic structure shows that the high Vickers hardness and elastic properties of WB12 and TiB12 derive from the 3D network B–B covalent bonds. In addition, the calculated Debye temperature at the ground state is 927 K for WB12 and 1339 K for TiB12, respectively. With increasing pressure, the calculated Debye temperature of WB12 and TiB12 increases gradually. Our work shows that TiB12 not only exhibits high hardness but also shows better thermodynamic properties in comparison with WB12.
A series of double-perovskite LaAMnNiO6 (A = La, Pr, Sm) catalysts with mesoporous morphology was prepared by a sol–gel method and further applied into photothermal synergistic degradation of gaseous toluene. Transmission electron microscopy and Brunauer–Emmett–Teller characterizations confirmed that double-perovskite LaAMnNiO6 (A = La, Pr, Sm) had obvious mesoporous structure, which can provide a larger specific surface area and further enhancing the reactivity of catalyst. UV-vis and X-ray photoelectron spectroscopy characterization illustrated that LaSmMnNiO6 possessed higher adsorption oxygen content and light absorption capacity, which contribute to the occurrence of catalytic oxidation in the Mars–van Krevelen redox cycle mechanism. A group of active tests showed that the double-perovskite LaSmMnNiO6 catalyst had a lower reaction initiation temperature (starting reaction at 75 °C) and a lower activity temperature of optimal reaction (more than 90% at 255 °C). Moreover, the research on reaction kinetics of the catalyst demonstrated that LaAMnNiO6 (A = La, Pr, Sm) had lower activation energy and thus exhibited better catalytic activity. The results of the study indicate that the double-perovskite LaAMnNiO6 (A = La, Pr, Sm) has broad application prospects in the field of volatile organic pollutant degradation.
In this study, an injectable bone substitute (IBS) was produced by mixing a liquid and powder phase. The liquid phase consisted of 8 wt% methylcellulose (MC), 2.5% gelatin, and different amounts of graphene oxide (GO). The powder phase was composed of tetracalcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD), and calcium sulfate dihydrate (CSD). The results showed that 1 and 1.5 wt% GO added IBS samples showed higher stability, injectability, rheological properties, and biocompatibility than the other GO added IBS samples. GO addition significantly decreased the setting time, but it did not significantly affect the compressive strength of the samples.
The recent observations of ferromagnetic order in several two-dimensional (2D) materials have generated an enormous interest in the physical mechanisms underlying 2D magnetism. In the present Prospective Article, we show that Density Functional Theory combined with either classical Monte Carlo simulations or renormalized spin-wave theory can predict Curie temperatures for ferromagnetic insulators that are in quantitative agreement with experiments. The case of materials with in-plane anisotropy is then discussed, and it is argued that finite size effects may lead to observable magnetic order in macroscopic samples even if long range magnetic order is forbidden by the Mermin–Wagner theorem.
Additional crystallographic data are given for the recently reported mineral middlebackite, which has been described for discoveries at Iron Knob in South Australia and Passo di San Lugano near Trento, Italy. The material examined in the present study was from a third finding of the mineral, viz. from a quartz outcrop at Mooloo Downs Station in Western Australia within which it was co-located with the chemically- and structurally-related mineral moolooite, CuIIC2O4·nH2O, reported by Clarke and Williams (1986). In this study, the crystal structure was elucidated independently of the other studies using a combination of the a priori charge flipping and simulated annealing methods with synchrotron radiation diffraction (SRD) powder data. The principal crystal data for the Mooloo Downs material are: space group P21/c with lattice parameters a = 7.2659(18) Å, b = 5.7460(11) Å, c = 5.6806(11) Å, β = 104.588(3)°; Vc = 229.46(18) Å3; empirical formula CuII2C2O4(OH)2 with 2 formula units per unit cell; and calculated density = 3.605 g cm−3. The lattice parameters agree approximately with values given for the other studies, but not within the reported error estimates. The atom coordinates, interatomic distances, and angles for the Mooloo Downs material are compared with those from the other studies using single crystal data, with the values from all three studies agreeing approximately, but again not within the reported uncertainties. The crystal chemistry found for middlebackite received strong confirmation through the synthesis for the first time of di-copper oxalate di-hydroxide. Laboratory X-ray diffraction powder data for the synthetic form of the mineral from this study agree closely with the SRD data for the natural mineral.
The third edition of the To.Sca.Lake Summer School, co-sponsored by ICDD, was organized on the Como Lake shore in Northern Italy, and has seen the participation of more than 50 attendees from four different continents. The main topic was Total Scattering Analysis in the real and reciprocal spaces (by the Pair Distribution Function and the Debye Scattering Equation approaches, respectively). with additional contributions on Small Angle X-ray Scattering and Light Scattering methods, the latter proposed in the static and dynamic modes.
Polarized resonant soft x-ray scattering (RSoXS) can leverage contrast between domains in mass, chemical bonds, and chain orientation to characterize polymer thin films. Although mass and chemical contrast can be predicted from the absorption spectra, the origins of orientational contrast are not fully understood. For example, in the case where one domain is crystalline, it is not obvious how the total crystallinity will affect the anisotropy. Using a simple calculation, we predict polarized RSoXS of model structures and compare with experiment. Through experiments and simulations, we demonstrate that scattering anisotropy is not monotonically related to local order but instead peaks when 50% of domains have aligned chains, i.e., when the sample is 50% crystalline.