Ag(I)-Catalyzed/Acid-Mediated Cascade Cyclization of ortho-Alkynylaryl-1,3-dicarbonyls to Access Arylnaphthalenelactones and Furanonaphthol Libraries via Aryl-Disengagement

ortho-Alkynylarylketone derivatives were employed as key precursors for a one-pot synthesis of arylnaphthalenelactone and furanonaphthol libraries. In this work, we discovered a cost-effective protocol to prepare arylnaphthalenelactones in one-pot using inexpensive starting material, malonate ester, which was conveniently functionalized leading to a variety of structures. Moreover, we also found an unexpected oxy-dearylation reaction which could be used to synthesize furanonaphthol analogs. These novel methods could be applied to a broad range of substrates to give the corresponding products in up to 83% yield. Notably, these classes of compounds exhibited more significant inhibition against protein-tyrosine phosphatase 1B (PTP1B) enzyme than a standard compound, ursolic acid.     

Thermal Emission Spectrum of the Cobalt Monobromide Molecule

ABSTRACT

The thermal emission spectrum of the CoBr molecule has been photographed for the first time in the spectral region 4200–6000 Å using the high-temperature excitation technique and the 2-meter plane grating spectrograph (PGS-2). The spectrum has been recorded at a reciprocal linear dispersion of 7.3 Å/mm. About 203 red degraded and line-like bands have been recorded, out of which 172 are entirely new. The observed bands have been classified into 31 systems, of which 23 are entirely new. The vibrational analyses have been carried out using band head measurements and the Deslandre table. The ground state of the CoBr molecule is found to be ³Φ with the vibrational constants 318.3, 329.5, and 332.7 cm^?1.     

Effect of Molecular Interactions on Electron‐Transfer and Antioxidant Activity of Bis(alkanol)selenides: A Radiation Chemical Study

Understanding electron‐transfer processes is crucial for developing organoselenium compounds as antioxidants and anti‐inflammatory agents. To find new redox‐active selenium antioxidants, we have investigated one‐electron‐transfer reactions between hydroxyl (^.OH) radical and three bis(alkanol)selenides (SeROH) of varying alkyl chain length, using nanosecond pulse radiolysis. ^.OH radical reacts with SeROH to form radical adduct, which is converted primarily into a dimer radical cation (>Se∴Se<)⁺ and α‐{bis(hydroxyl alkyl)}‐selenomethine radical along with a minor quantity of an intramolecularly stabilized radical cation. Some of these radicals have been subsequently converted to their corresponding selenoxide, and formaldehyde. Estimated yield of these products showed alkyl chain length dependency and correlated well with their antioxidant ability. Quantum chemical calculations suggested that compounds that formed more stable (>Se∴Se<)⁺, produced higher selenoxide and lower formaldehyde. Comparing these results with those for sulfur analogues confirmed for the first time the distinctive role of selenium in making such compounds better antioxidants.     

Solvothermal synthesis and luminescent properties of Y2Ti2O7:Eu3+ spheres

Pyrochlore‐structured yttrium titanate phosphors activated by trivalent europium ions (Y₂Ti₂O₇(YT):Eu³⁺), with spherical morphology, were synthesized at different pH values by a solvothermal process. From the structural and morphological measurements, the annealing temperature had no effect on the spherical morphology of the YT:Eu³⁺ sample. The photoluminescence excitation and emission spectra were taken by activating the Eu³⁺ ions in the YT host lattice as functions of Eu³⁺ ion concentration and annealing temperature. The optimal doping concentration was found to be 4 mol%, exhibiting an excellent orange–red emission due to the highest intensity of the ⁵D₀ → ⁷F₁ transition. When the YT:Eu³⁺ phosphor was mixed with YAG:Ce³⁺ phosphor, a brilliant white light emission was achieved. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Local surface damage and material dissolution in 45S5 bioactive glass: Effect of the contact deformation

Bioactive glasses react with the human physiological solution in control of their biofunctionality. The stress state in bioactive glasses determines the chemomechanical reaction and their biofunctionality. Using the microindentation technique, the effect of the indentation deformation on the surface damage and material dissolution of 45S5 bioglass was investigated. The indentation-induced local surface damage, including ring cracks and radial cracks, was revealed before and after the immersion tests in phosphate buffer solution (PBS). There existed a critical load for the formation of the radial cracks, which emanated from the periphery of the outmost ring crack. The growth of the radial cracks in the PBS solution displayed the stress-corrosion behavior with the crack-growth speed being a linear function of the indentation load. Fast dissolution occurred at the edges of the surface-damaged zone due to stress-assisted dissolution under the action of local tensile stress, which was different from the dissolution behavior of stress-free 45S5 bioglass.     

Numerical study of the hydrodynamics and heat transfer characteristics of gas–solid in a slit-less rotating fluidized bed in static geometry

Journal of Thermal Analysis and Calorimetry - A rotating fluidized bed in static geometry (RFB-SG) without slits is presented in this paper as a research objective. The concept of RFB-SG is highly...     

A novel strategy for controllable emissions from Eu3+ or Sm3+ ions co-doped SrY2O4:Tb3+ phosphors

Trivalent rare-earth (RE) ions (Eu(3+), Tb(3+) and Sm(3+)) activated multicolor emitting SrY(2)O(4) phosphors were synthesized by a sol-gel process. The structural and morphological studies were performed by the measurements of X-ray diffraction profiles and scanning electron microscope (SEM) images. The pure phase of SrY(2)O(4) appeared after annealing at 1300 °C and the doping of RE ions did not show any effect on the structural properties. From the SEM images, the closely packed particles were observed due to the roughness of each particle tip. The photoluminescence (PL) analysis of individual RE ions activated SrY(2)O(4) phosphors exhibits excellent emission properties in their respective regions. The Eu(3+) co-activated SrY(2)O(4):Tb(3+) phosphor creates different emissions by controlling the energy transfer from Tb(3+) to Eu(3+) ions. Based on the excitation wavelengths, multiple (green, orange and white) emissions were obtained by Sm(3+) ions co-activated with SrY(2)O(4):Tb(3+) phosphors. The decay measurements were carried out for analyzing the energy transfer efficiency and the possible ways of energy transfer from donor to acceptor. The cathodoluminescence properties of these phosphors show similar behavior as PL properties except the energy transfer process. The obtained results indicated that the energy transfer process was quite opposite to the PL properties. The calculated CIE chromaticity coordinates of RE ions activated SrY(2)O(4) phosphors confirmed the red, green, orange and white emissions.