Phase diagram of SrO-InO1.5-CoOx and a new compound Sr3In0.9Co1.1O6

Sr₃In_0.9Co_1.1O₆, isostructural to Ca₃Co₂O₆, is revealed by the study of the phase relations in the system SrO-InO_1.5-CoO_x (1000 °C). The structure of Sr₃In_0.9Co_1.1O₆ is refined by the combination of powder X-ray and neutron diffraction. Sr₃In_0.9Co_1.1O₆ crystallizes in a trigonal lattice with the cell parameters a=b=9.59438(3) Å, c=11.02172(4) Å with the space group R-3c. Its structure possesses 1D (In/Co)O₃ chains running along the c-axis constructed by alternating face-sharing CoO₆ octahedra and (In_0.9Co_0.1)O₆ trigonal prisms. The co-occupation of In³⁺ and Co³⁺ at the trigonal prismatic site is evidenced by elementary analysis and determined by the structure refinement. Sr₃In_0.9Co_1.1O₆ is paramagnetic, and the susceptibility is consistent with the occupation of Co³⁺ at 10% of the trigonal prismatic positions in a high spin state (HS, S=2). The HS Co³⁺ is well separated by diamagnetic CoO₆ octahedra and InO₆ trigonal prisms and shows a g factor of 2.0 in the magnetic measurements.     

Inelastic neutron scattering and lattice dynamics of GaPO<Subscript>4</Subscript>

We report here measurements of phonon spectrum and lattice dynamical calculations for GaPO₄. The measurements in low-cristobalite phase of GaPO₄ are carried out using high-resolution medium-energy chopper spectrometer at ANL, USA in the energy transfer range 0–160 meV. Semiempirical interatomic potential in GaPO₄, previously determined using ab-initio calculations have been widely used in studying the phase transitions among various polymorphs. The calculated phonon spectrum using the available potential show fair agreement with the experimental data. However, the agreement between the two is improved by including the polarisability of the oxygen atoms in the framework of the shell model. The lattice dynamical models are also exploited for calculations of various thermodynamic properties of GaPO₄.     

Effect of CO2 adsorbents on the Ni-based dual-function materials for CO2 capturing and in situ methanation

The present work studied the effect of different carbon dioxide (CO₂) adsorbents on Ni-based dual-function materials (DFMs) for the development of carbon capture and on-site utilization in a reactor at isothermal condition. The DFMs containing Ni functioning as a methanation catalyst with various CO₂ adsorbents (i.e., CaO, MgO, K₂CO₃, or Na₂CO₃) were prepared on γ-Al₂O₃ through sequential impregnation. The result indicated that Ni-Na₂CO₃/γ-Al₂O₃ had the highest methanation capacity (i.e., 0.1783 mmol/g) and efficiency (i.e., 71.09%) in the CO₂ adsorption–methanation test. The CO₂ uptake and the subsequent methanation capacity of the Ni-Na₂CO₃/γ-Al₂O₃ increased to more than 24 times and more than 17 times, respectively, compared to Ni/γ-Al₂O₃. The high methanation capacity was correlated to its highest amount of weak basic sites, substantial CO₂ capture capacity and capture/release efficiency, and reactivity to H₂ at a lower temperature, supported by CO₂-TPD, TGA analyses for adsorption or adsorption–desorption at the isothermal condition, and H₂-TPRea, respectively. A continuous cyclic CO₂ adsorption–methanation was performed by using the Ni-Na₂CO₃/γ-Al₂O₃ and Ni-CaO/γ-Al₂O₃, showing that the CO₂ adsorption capacity was stabilized from third cycle onward, whereas the methanation capacity was stabilized at all cycles, indicating the high stability of the DFMs for both CO₂ adsorption and subsequent methanation. This work demonstrated successful synthesis of the Ni-based, low-cost, and stable DFMs with the ability to produce methane via the direct capture of CO₂.     

Time‐Dependent Photodynamic Therapy for Multiple Targets: A Highly Efficient AIE‐Active Photosensitizer for Selective Bacterial Elimination and Cancer Cell Ablation

Pathogen infections and cancer are two major human health problems. Herein, we report the synthesis of an organic salt photosensitizer (PS), called 4TPA‐BQ, by a one‐step reaction. 4TPA‐BQ presents aggregation‐induced emission features. Owing to the aggregation‐induced reactive oxygen species generated and a sufficiently small ΔE_ST, 4TPA‐BQ shows a satisfactorily high ¹O₂ generation efficiency of 97.8 %. In vitro and in vivo experiments confirmed that 4TPA‐BQ exhibited potent photodynamic antibacterial performance against ampicillin‐resistant Escherichia coli with good biocompatibility in a short time (15 minutes). When the incubation duration persisted long enough (12 hours), cancer cells were ablated efficiently, leaving normal cells essentially unaffected. This is the first reported time‐dependent fluorescence‐guided photodynamic therapy in one individual PS, which achieves ordered and multiple targeting simply by varying the external conditions. 4TPA‐BQ reveals new design principles for the implementation of efficient PSs in clinical applications.     

Elucidation of Gram-Positive Bacterial Iron(III) Reduction for Kaolinite Clay Refinement

Recently, microbial-based iron reduction has been considered as a viable alternative to typical chemical-based treatments. The iron reduction is an important process in kaolin refining, where iron-bearing impurities in kaolin clay affects the whiteness, refractory properties, and its commercial value. In recent years, Gram-negative bacteria has been in the center stage of iron reduction research, whereas little is known about the potential use of Gram-positive bacteria to refine kaolin clay. In this study, we investigated the ferric reducing capabilities of five microbes by manipulating the microbial growth conditions. Out of the five, we discovered that Bacillus cereus and Staphylococcus aureus outperformed the other microbes under nitrogen-rich media. Through the biochemical changes and the microbial behavior, we mapped the hypothetical pathway leading to the iron reduction cellular properties, and found that the iron reduction properties of these Gram-positive bacteria rely heavily on the media composition. The media composition results in increased basification of the media that is a prerequisite for the cellular reduction of ferric ions. Further, these changes impact the formation of biofilm, suggesting that the cellular interaction for the iron(III)oxide reduction is not solely reliant on the formation of biofilms. This article reveals the potential development of Gram-positive microbes in facilitating the microbial-based removal of metal contaminants from clays or ores. Further studies to elucidate the corresponding pathways would be crucial for the further development of the field.     

Tensile strength of aluminium nitride films

Two-layered aluminium nitride (AlN)/silicon nitride microbridges were fabricated for microbridge tests to evaluate the elastic modulus, residual stress and tensile strength of the AlN films. The silicon nitride layer was added to increase the robustness of the structure. In a microbridge test, load was applied to the centre of a microbridge and was gradually increased by a nano-indenter equipped with a wedge tip until the sample was broken, while displacement was recorded coherently. Measurements were performed on single-layered silicon nitride microbridges and two-layered AlN/silicon nitride microbridges respectively. The data were fitted to a theory to derive the elastic modulus, residual stress and tensile strength of the silicon nitride films and AlN films. For the AlN films, the three parameters were determined to be 200, 0.06 and 0.3?GPa, respectively. The values of elastic modulus obtained were consistent with those measured by conventional nano-indentation method. The tensile strength value can be used as a reference to reflect the maximum tolerable tensile stress of AlN films when they are used in micro-electromechanical devices.     

Effects of excess oxygen content on the hole-carrying CuO2-layers in Tl2(Ba1−xSrx)2Ca2Cu3Oy superconducting oxides

The effects of oxygen doping on the hole-carrying CuO₂-layers in Tl₂(Ba_1−xSr_x)₂Ca₂Cu₃O_y were studied by combined chemical and valence analysis, T_c measurements and neutron diffraction. The highest T_c is characterized by an optimal excess oxygen content, Δy, dichotomizing the under- and over-doped regions for each Sr concentration. While the average Tl valence is close to 3.0 and independent of Δy, the average Cu valence shows a linear dependence with Δy. An increase of the flatness of the CuO₂ plane, characterized by the O(2)-Cu(2)-O(2) bond angle of ∼176°, was observed at the optimal Δy.     

Effects of poly(ethylene oxide) and pH on the electrospinning of whey protein isolate

Poly(ethylene oxide) (PEO) is known for facilitating the electrospinning of biopolymer solutions, which are otherwise not electrospinnable. The objective of this study was to improve the understanding of the positive effects of PEO on the electrospinning of whey protein isolate (WPI) solutions under different pH conditions. Alterations in protein secondary structure and polymer solution properties (viscosity, conductivity, and dynamic surface tension), as induced by pH changes, significantly affected the electrospinning behavior of WPI/PEO (10% w/w: 0.4% w/w PEO) solutions. Acidic solutions resulted in smooth fibers (707 ± 105 nm) while neutral solutions produced spheres (2.0 ± 1.0 μm) linked with ultrafine fibers (138 ± 32 nm). In comparison, alkaline solutions produced fibers (191 ± 36 nm) that were embedded with spindle‐like beads (1.0 ± 0.5 μm). ¹³C NMR and FTIR spectroscopies showed that the increase in random coil and α‐helix secondary structures in WPI were the main contributors to the formation of bead‐less electrospun fibers. The electrospinning‐enabling properties of PEO on aqueous WPI solutions were attributed to physical chain entanglement between the two polymers, rather than specific polymer–polymer interactions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Raman investigations of rare‐earth arsenate single crystals

Polarized Raman spectroscopy was used to investigate the room‐temperature phonon characteristics of a series of rare‐earth arsenate (REAsO₄, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumbers of the internal modes of the AsO₄ tetrahedron increased with increasing atomic number. This increase seems to be correlated to the contraction of the RE–O bond length. For three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber. Copyright © 2009 John Wiley & Sons, Ltd.