Evolution of photoluminescence across dimensionality in lanthanide silicates

The dehydratation process of layered lanthanide silicates K3[LnSi3O8(OH)2], Ln = Y, Eu, Tb, and Er, and the structural characterization of the obtained small-pore framework K3LnSi3O9, Ln = Y, Eu, Tb, and Er solids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-ray diffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electron microscopy, and 29Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 have been studied and compared with those of AV-22. Both materials have a similar chemical makeup and structures sharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution of the PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a single crystallographic Tb(3+) site, PL spectroscopy indicates the presence of Ln(3+) centers in regular framework positions and in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln(3+) environment, namely, Eu(3+) ions replacing K(+) ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samples are of the same order of magnitude as those of standard Tb(3+) green phosphors. For the samples K3(Y1-aEraSi3O9), a = 0.005-1, efficient emission and larger 4I13/2 lifetimes (ca. 7 ms) are detected for low Er(3+) content, indicating that the Er(3+)-Er(3+) interactions become significant as the Er(3)+ content increases.     

Molecular and Conformational Properties of Dendronized Polymethacrylate in Organic Solvent

The conformational and dynamo-optical properties of a homologous series of polymethacrylate modified by first-generation Fréchet-type dendrons in the molecular mass range of 70–8800 kDa in organic solvents were studied by viscometry, isothermal diffusion, dynamic light scattering, and flow birefringence. The Mark-Kuhn-Houwink equations for this dendronized polymer in toluene and chloroform together with hydrodynamic diameter and Kuhn segment length in toluene are defined as well as the value of intrinsic anisotropy of polarizability for the monomer unit.     

光波导乙醇气体传感器的研究

以聚偏氟乙烯(PVDF)作为敏感试剂固定在钾(K⁺)离子交换玻璃光波导表面,研制了光波导乙醇气体传感器.该传感器具有可逆性好、灵敏度高、响应速度快、选择性和重现性好、能在室温操作等特点.     

Benzyl-para-di-[5-methyl-4-(n-octylamino) pyrimidin-2(1H)one] as an interferon beta (IFN-β) modulator

Molecular Diversity - IFN-β is a cytokine that plays a significant role in the immune system. Inhibition of IFN-β might be used as a therapeutic approach to treat septic shock. A...     

The limitations of cupping in the local structure of the enumeration degrees

We prove that a sequence of sets containing representatives of cupping partners for every nonzero D⁰₂{\Delta^0_2} enumeration degree cannot have a D⁰₂{\Delta^0_2} enumeration. We also prove that no subclass of the S⁰₂{\Sigma^0_2} enumeration degrees containing the nonzero 3-c.e. enumeration degrees can be cupped to 0_e￠{\mathbf{0}_e'} by a single incomplete S⁰₂{\Sigma^0_2} enumeration degree.