Antibacterial wollastonite supported excellent proliferation and osteogenic differentiation of human bone marrow derived mesenchymal stromal cells

Journal of Sol-Gel Science and Technology - Biocompatibility and bacterial infections are the primary concerns associated with the current bone graft substitutes. The application of...     

The phane properties of anti-[2.2](1,4)biphenylenophane

[structure: see text] Anti-[2.2](1,4)biphenylenophane (4) was synthesized from de Meijere's tetrabromo[2.2]paracyclophane (5) through a four-step reaction sequence. Although an average separation of 3.09 A between the inner ring of the biphenylene units is normal for [2.2]paracyclophanes, a bond distance of 1.54 Afor the ethano C-C bridge at room temperature is shorter than usual. In addition, trimethylsilyl-substituted anti-[2.2](1,4)biphenylenophane 8 sublimes at 220 degrees C under a pressure lower than 1 x10(-5) Torr without decomposition or thermal isomerization. The high thermal stability of 8 suggested that the ethano bridges of the biphenylenophanes are less strained than those of [2.2]paracyclophane. Bathochromic shifts are observed in their UV-vis absorption spectra. The phane state interactions of 4 and 8 were evidenced by the weak structureless fluorescent emission maximized at 537 and 550 nm in CH(2)Cl(2) along with longer relaxation lifetimes of 229 and 292 ps, respectively.     

Erratum to: Sol–gel synthesis of mesoporous WO3–TiO2 composite thin films for photochromic devices

Mesoporous WO₃–TiO₂ composite films were prepared by a sol gel based two stage dip coating method and subsequent annealing at 450, 500 and 600 °C. An organically modified silicate based templating strategy was adopted in order to obtain a mesoporous structure. The composite films were prepared on ITO coated glass substrates. The porosity, morphology, and microstructures of the resultant products were characterized by scanning electron microscopy, N₂ adsorption–desorption measurements, μ-Raman spectroscopy and X-ray diffraction. Calcination of the films at 450, and 500 °C resulted in mixed hexagonal (h) plus monoclinic phases, and pure monoclinic (m) phase of WO₃, respectively. The degree of crystallization of TiO₂ present in these composite films was not evident. The composite films annealed at 600 °C, however, consist of orthorhombic (o) WO₃ and anatase TiO₂. It was found that the o-WO₃ phase was stabilized by nanocrystalline anatase TiO₂. The thus obtained mesoporous WO₃–TiO₂ composite films were dye sensitized and applied for the construction of photochromic devices. The device constructed using dye sensitized WO₃–TiO₂ composite layer heat treated at 600 °C showed an optical modulation of 51 % in the NIR region, whereas the devices based on the composite layers heat treated at 450, and 500 °C showed only a moderate optical modulation of 24.9, and 38 %, respectively. This remarkable difference in the transmittance response is attributed to nanocrystalline anatase TiO₂ embedded in the orthorhombic WO₃ matrix of the WO₃–TiO₂ composite layer annealed at 600 °C.     

One-step low-temperature solid-state synthesis of lead-free cesium copper halide Cs3Cu2Br5 phosphors with bright blue emissions

The development of new efficient and environmental-friendly inorganic phosphors is highly important for phosphor-converted white light-emitting diodes and optoelectronic displays. In this paper, we report a novel and simple one-step solid-state reaction to synthesize lead-free cesium copper halide Cs₃Cu₂Br₅ powders with bright blue emission around 460 nm. The preparation process is performed at low calcination temperatures (290–320 °C) and requires no complex apparatus, reagents, or techniques, and thus it holds great potential for mass production of halide emitters. The Cs₃Cu₂Br₅ powder phosphors are characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence excitation and emission spectroscopy, CIE color coordinates, color purity, photoluminescence quantum yield, and temperature-dependent emission spectra. The effect of calcination temperature on the photoluminescence properties of the as-prepared Cs₃Cu₂Br₅ blue phosphors has been investigated and the air-stability property has also been discussed. Impressively, Cs₃Cu₂Br₅ blue phosphors show outstanding stability toward air exposure exceeding one month (30 days). Our work will open a new and simple approach to obtain excellent halide emitters for future solid-state lighting and displays.     

Al-H bond formation in hydrated aluminum oxide cluster anions

Quantum chemical calculations have been performed to investigate the interaction of a water molecule with gas phase aluminum oxide cluster anions. While oxygen-rich clusters (AlxOy-,xy) generate metal hydrides. These hydride species are, in many cases, 30-35 kcal/mol more stable than their hydroxide counterparts. Our observations on such competing reaction pathways may be useful to understand the catalytic role of alumina nanoparticles in many chemical reactions.     

Small elemental clusters. I. The structures of Be2, Be3, Be4, and Be5

The geometries and energies of beryllium clusters up to Be₅ are examined using ab initio molecular orbital theory. Allowances are made for electron correlation with Møller—Plesset perturbation theory to fourth order. Correlation is found to have a dramatic effect on the relative energies of the several structures examined for Be₄ and Be₅. Furthermore, the effect of d-type basis functions on the correlation energy results in an increased binding energy for the clusters. Be₂ is only weakly bound. For Be₃, the best estimate of the binding energy is 6 kcal/mole for the singlet equilateral triangle. Be₄ is tetrahedral in its ground state and the estimated binding is 56 kcal/mole. The best structure for Be₅ is a singlet trigonal bipyramid, and the binding energy is 88 kcal/mole at the highest level of theory used.     

Hydrogen adsorption on the indium-rich indium phosphide (001) surface: a novel way to produce bridging In-H-In bonds

The indium phosphide (001) surface provides a unique chemical environment for studying the reactivity of hydrogen toward the electron-deficient group IIIA element, indium. Hydrogen adsorption on the In-rich delta(2 x 4) reconstruction produced a neutral, covalently bound bridging indium hydride. Using vibrational spectroscopy and ab initio cluster calculations, two types of bridging hydrides were identified, a (mu-H)In(2) and a (mu-H)(2)In(3) "butterfly-like" structure. These structures were formed owing to the large thermodynamic driving force for adsorption of H atoms on solid-state indium dimers.     

Cyclic C3 structures

Alternative cyclic C₃ structures are not competitive energetically with the linear ¹∑_g⁺ ground state, 1. The D₃h triplet, 4, is a local minimum on the potential energy surface. Cyclopropynylidene, a C_2v singlet (3) is a saddle point for the degenerate isomerization which permutes the order of carbon atoms in 1. The activation energy for this transformation is predicted to be 29 kcal/mole.