Structural and photoluminescence studies on europium-doped lithium tetraborate(Eu:Li_2B_4O_7) single crystal grown by microtube Czochralski(μT-Cz) technique

Rare earth europium(Eu(3+))-doped lithium tetraborate(Eu:Li_2B_4O_7) crystal is grown from its stoichiometric melt by microtube Czochralski pulling technique(μT-Cz) for the first time. The grown crystals are subjected to powder x-ray diffraction(PXRD) analysis which reveals the tetragonal crystal structure of the crystals. UV–vis–NIR spectral analysis is carried out to study the optical characteristics of the grown crystals. The crystal is transparent in the entire visible region, and the lower cutoff is observed to be at 304 nm. The existence of BO_3 and BO_4 bonding structure and the molecular associations are analyzed by Fourier transform infrared(FTIR) spectroscopy. The results of excitation and emission-photoluminescence spectra of europium ion incorporated in lithium tetraborate(LTB) single crystal reveal that the observations of peaks at 258,297, and 318 nm in the excitation spectra and peaks at 579, 591, 597, 613, and 651 nm are observed in the emission spectra.The chromaticity coordinates are calculated from the emission spectra, and the emission intensity of the grown crystal is characterized through a CIE 1931(Commission International d'Eclairage) color chromaticity diagram.     

Synthesis,spectroscopic characterization and crystal structure of 5-bromo-1-(2-cyano-pyridin-4-yl)-1H-indazole-3-carboxylic acid diethylamide

The title compound 5-bromo-1-(2-cyano-pyridin-4-yl)-1H-indazole-3-carboxylic acid diethylamide, C₁₈H₁₆BrN₅O, is prepared from 5-bromoindazole-3-carboxylic acid methylester. N ¹-arylation is carried out with 4-chloro-2-cyanopyridine and the resulting product is converted to diethylamide by reacting with thionyl chloride and diethylamine. The structure is identified from its FT-IR, ¹H NMR, ¹³C NMR spectroscopy, elemental analysis data and unambiguously confirmed by single crystal X-ray diffraction studies. There are two symmetry independent molecules in the asymmetric unit with no significant differences in bond lengths and angles. The title compound crystallizes in the triclinic system, space group \(P\bar 1\) , with a = 11.2330(2); b = 11.6130(2); c = 15.4710(3) Å, α = 92.515(1)°; β = 109.956(1)°; γ = 107.199(1)°; V = 1788.45(6)ų and z = 4. An intramolecular C-H…N hydrogen bond forms an S(6) ring motif in one of the unique molecules. In the crystal, two molecules are linked about a center of inversion by C-H…O hydrogen bonded dimers generating an R ₂ ² (16) ring motif. The crystal packing is stabilized by C-H…N, C-H…O hydrogen bonds and π…π stacking interactions.     

Incorporation and controlled release of silyl ether prodrugs from PRINT nanoparticles

Asymmetric bifunctional silyl ether (ABS) prodrugs of chemotherapeutics were synthesized and incorporated within 200 nm × 200 nm particles. ABS prodrugs of gemcitabine were selected as model compounds because of the difficulty to encapsulate a water-soluble drug within a hydrogel. The resulting drug delivery systems were degraded under acidic conditions and were found to release only the parent or active drug. Furthermore, changing the steric bulk of the alkyl substituents on the silicon atom could regulate the rate of drug release and, therefore, the intracellular toxicity of the gemcitabine-loaded particles. This yielded a family of novel nanoparticles that could be tuned to release drug over the course of hours, days, or months.     

A pattern recognition system for JPEG steganography detection

This paper builds up a pattern recognition system to detect anomalies in JPEG images, especially steganographic content. The system consists of feature generation, feature ranking and selection, feature extraction, and pattern classification. These processes tend to capture image characteristics, reduce the problem dimensionality, eliminate the noise inferences between features, and further improve classification accuracies on clean and steganography JPEG images. Based on the discussion and analysis of six popular JPEG steganography methods, the entire recognition system results in higher classification accuracies between clean and steganography classes compared to merely using individual feature subset for JPEG steganography detection. The strength of feature combination and preprocessing has been integrated even when a small amount of information is embedded. The work demonstrated in this paper is extensible and can be improved by integrating various new and current techniques.     

Calcium-Dependent Translocation of S100B Is Facilitated by Neurocalcin Delta

S100B is a calcium-binding protein that governs calcium-mediated responses in a variety of cells—especially neuronal and glial cells. It is also extensively investigated as a potential biomarker for several disease conditions, especially neurodegenerative ones. In order to establish S100B as a viable pharmaceutical target, it is critical to understand its mechanistic role in signaling pathways and its interacting partners. In this report, we provide evidence to support a calcium-regulated interaction between S100B and the neuronal calcium sensor protein, neurocalcin delta both in vitro and in living cells. Membrane overlay assays were used to test the interaction between purified proteins in vitro and bimolecular fluorescence complementation assays, for interactions in living cells. Added calcium is essential for interaction in vitro; however, in living cells, calcium elevation causes translocation of the NCALD-S100B complex to the membrane-rich, perinuclear trans-Golgi network in COS7 cells, suggesting that the response is independent of specialized structures/molecules found in neuronal/glial cells. Similar results are also observed with hippocalcin, a closely related paralog; however, the interaction appears less robust in vitro. The N-terminal region of NCALD and HPCA appear to be critical for interaction with S100B based on in vitro experiments. The possible physiological significance of this interaction is discussed.     

Supersymmetry and the ladder operator technique in quantum mechanics: The radial Schrödinger equation

Using the ladder operator technique, a construction of the supersymmetric Hamiltonian is proposed. We show that the accidental degeneracies associated with the Coulomb and isotropic oscillator problems may be attributed to the existence of a supersymmetry of the Hamiltonians.     

pH-Dependent self-assembly of water-soluble sulfonate-tetraphenylethylene with aggregation-induced emission

The fabrication of well-defined nanostructures with luminescent properties in the solid or aggregated state is of intense interest due to their applications in nano- and biotechnology. We report the synthesis of water-soluble tetraphenylethylene bearing four sulfonate groups as a sodium salt (Su-TPE), and investigations concerning its AIE characteristics by the addition of organic solvent into the aqueous solution, which is the reverse procedure to conventional AIE-active TPE derivatives. The resultant compound is weakly emissive in pure water, however, emits strongly upon addition of THF solvent (with THF fraction > 60%). The emission properties and the morphologies of the aggregates were greatly dependent upon the solution pH. Su-TPE self-assembled into variety of structures in water/THF mixture with pH control, for the first time. Well-defined uniform nanorods with a width of about 200 nm and a length of up to 10 μm were obtained at solution pH of 1. The Su-TPE showed very good mechanochromic properties were observed during the process of grounding and fuming.     

Formation constants ofN-o-tolylbenzohydroxamic acids with manganese(II), nickel(II), copper(II) and zinc(II)

Summary The thermodynamic metal ligand stability constants with some divalent metal ions ofN-o-tolylbenzohydroxamic acids at 25° and 35° were determined in 11 dioxan:water. The order of stability constants is discussed.