An efficient multicomponent synthesis and in vitro anticancer activity of dihydropyranochromene and chromenopyrimidine-2,5-diones

A series of dihydropyranochromenes and chromenopyrimidine-2,5-diones having chromene scaffold were synthesized via efficient multicomponent protocol in aqueous β-cyclodextrin. The reaction is free of toxic solvents, operating under mild conditions and allows for ease of product isolation, making it more environmentally friendly. All the synthesized compounds biologically evaluated for their potential inhibitory effect on both cervical cancer cell line (HeLa) and human breast adenocarcinoma cell line (MCF-7). Of these compounds, 4d was found to be the most potent inhibitors of HeLa and MCF-7 demonstrating IC₅₀ values of 19?µM and 7?µM. Compounds 4b, 4e and 4f also shown significantly good in vitro anticancer activity against HeLa and MCF-7 cancer cell lines.     

Organocatalytic mediated green approach: A versatile new L-valine promoted synthesis of diverse and densely functionalized 2-amino-3-cyano-4H-pyrans

The discovery of a new L-valine promoted facile and versatile green synthesis of diversified 2-amino-3-cyano-4H-pyrans using a one pot multicomponent-tandem reaction of aromatic aldehydes, malononitrile, and diverse electron-rich enolizable carbonyl compounds is described. To the best of our knowledge this is the first report on the use of native L-valine as a catalyst in organic synthesis. Environmental friendly, mild reaction conditions, use of easily available inexpensive starting materials, short reaction time, excellent yields, high atom economy, and recyclability of organocatalyst are the major advantages of the disclosed protocol.     

Electrochemical Synthesis of Chitosan‐co‐polyaniline/WO3⋅nH2O Composite Electrode for Amperometric Detection of NO2 Gas

An electrode of hydrated tungsten oxide (WO₃?nH₂O) embedded chitosan‐co‐polyaniline (CHIT‐co‐PANI) composite was electrochemically prepared on an indium tin oxide (ITO) coated glass surface using mineral acid as a supporting electrolyte. The resulting CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode was characterized using ultraviolet‐visible spectroscopy (UV‐vis), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The composite electrode exhibited a three‐dimensional nanofibrous structure with the diameter of the nanofibers ranging from 20 to 100 nm. The CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode allowed for the low potential detection of NO₂ gas in acidic medium. The NO₂ gas sensing characteristics were studied by measuring change in the current with respect to concentration and time. Using the CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode, NO₂ gas was detected electrochemically without interference at pH 2.0 and 0.25 V vs. Ag/AgCl. The current of the electrochemical cell with the CHIT‐co‐PANI/WO₃?nH₂O/ITO electrode decreased linearly with an increase in NO₂ gas concentration in a range from 100 to 500 ppb with a response time of eight seconds.     

Synthesis,characterization, and hoping transport properties of HCl doped conducting biopolymer‐co‐polyaniline zwitterion hybrids

A series of electrically conductive zwitterion hybrid materials were facilely synthesized with anionic acacia gum (AG) and cationic HCl doped polyaniline (PANI) through radical copolymerization method. A representative acacia gum‐polyaniline hybrid (AG‐PANI) was characterized using UV‐vis, FTIR, ¹H NMR, and SEM. HCl doped AG‐PANI possesses zwitterion character due to the presence of NH on PANI and ? COO^? of AG. The cyclic voltammogram of AG‐PANI showed three anodic peaks at 0.20 V, 0.58 V, and 0.64 V along with two cathodic peaks at 0.50 V and 0.40 V with large capacitive background currents. AG‐PANI exhibited electrical conductivity that was found dependent on the ratio of aniline to AG, temperature, and pH. Its electrical conductivity versus temperature plot indicated Mott's nearest‐neighbor hopping mechanism at the temperature range 83–323 K. The hybridization of AG and PANI yielded eco‐friendly advanced functional materials for technological applications. Copyright © 2008 John Wiley & Sons, Ltd.     

An interactive graphical user interface (GUI) for the CATGIXRF program – for microstructural evaluation of thin film and impurity doped surfaces

This paper is a continuation and extension of our earlier work (X‐ray Spectrom. 2010 , 39, 127–134, DOI:10.1002/xrs.1215) on the development of a software platform CATGIXRF, as a solution to provide non‐destructive evaluation of nanostructured materials. Here, we describe an interactive graphical user interface (GUI) for the CATGIXRF program. The newly developed GUI interface facilitates determination of microstructural parameters on angstrom length scale for the nanostructured thin layered materials using synchrotron as well as laboratory X‐ray sources. It allows combined analysis capabilities for both the X‐ray reflectivity and grazing incidence X‐ray fluorescence (GIXRF) data simultaneously, thus enabling us a greater sensitivity for the determination of microstructural parameters such as thickness, interface mixing, and roughness of a thin film medium with improved accuracies. The utility and various newly added salient features of the GUI‐CATGIXRF program are described by providing example calculations as well as by analyzing experimentally a few thin film structures with different surface‐interface properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Configuration-selective spectroscopic studies of Er3+ centers in ErSc2N@C80 and Er2ScN@C80 fullerenes

Low temperature photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of high purity ErSc(2)N@C(80) and Er(2)ScN@C(80) fullerenes reveal at least two metastable configurations of the Er(3+) ion within the cage, consistent with previous observations from x-ray diffraction. Using PLE measurements at a number of different emission wavelengths we have characterized the ground state, (4)I(152), and the first excited state, (4)I(132), of the various Er(3+) configurations and their crystal-field splitting. We present detailed energy level diagrams for the ground and excited states of the two dominant configurations of ErSc(2)N@C(80) and Er(2)ScN@C(80).     

Small silicon memories: confinement, single-electron,. and interface state considerations

Memories that utilize single-electron effects are an attempt at combining the discreteness observable in transport of electrons on to very small capacitances (∼10^-18 F) and into three-dimensionally quantum-confined states, with the reproducibility, architecture and integration of the field-effect devices. We discuss the role size plays in the operation and its variability for such memories. In particular, we discuss the implications of size effects through barriers on speed; through electrostatics on variability, acceptability and reproducibility of properties desired; through random variations and of tunneling on limits in the use of the field-effect, and through interface-states on the time-domain operation. For device properties and their variations, using silicon-on-insulator substrates, silicon and back-insulator thicknesses matter through the linear variations introduced in the electrostatic potential and quadratic variations introduced in the subband energies, the quantum-dots and nano-crystals matter secondarily through the electrostatics and the linear dependence of capacitance on size and the quadratic dependence of the allowed eigen-energies on size. We also discuss the implications of tunneling on time constants of charging of the confined states and in between the source and the drain for the ultimate structure size limit. Received: 14 April 2000 / Accepted: 17 April 2000 / Published online: 6 September 2000     

Formation of a new F.C.C. τ2 phase in rapidly quenched Al55Cu35V10 alloy

X‐ray diffraction and transmission electron microscopy experiments were carried out to study the structure of rapidly solidified as‐cast and annealed Al₅₅Cu₃₅V₁₀ alloy. The as‐cast Al₅₅Cu₃₅V₁₀ alloy shows the presence of a new f.c.c. τ2 phase (a=0.58nm) along with a b.c.c. (a = 0.89 nm) phase which after subsequent annealing transforms into single f.c.c. phase (a = 0.58 nm). In this paper, it is also reported that these phases are crystalline approximants to an icosahedral phase on the basis of e/a (valence electron per atom) constant line. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and Biological Activity of 2′-Fluoro-D-arabinofuranosylpyrazolo[3,4-d]pyrimidine Nucleosides

Coupling of 2-fluoro-3,5-di-O-benzoyl-α-D -arabinofuranosyl bromide with 4-methoxypyrazolo[3,4-d]pyrimidine gave an α-D /β-D mixture of N¹- and N²-coupled products. All the anomers were separated and deblocked to yield the corresponding nucleosides. The β-D -anomer 7 was converted to the 4-amino derivative 11 , which was deaminated by adenosine deaminase to give the 4-oxo compound 12 . Compound 7 showed significant activity against human cytomegalovirus and hepatitis B virus, and compound 11 showed activity against human herpes virus 8. All the compounds were noncytotoxic in several human tumor-cell lines in culture.