Ionic liquid-functionalized magnetic nanostructures as an efficient catalyst for the synthesis of 6H-chromeno[4,3-b]quinolin-6-ones

A novel imidazole ionic liquid (IL)-functionalized \(\hbox {silica}@\gamma \)-\(\hbox {Fe}_{2}\hbox {O}_{3}\) (\(\hbox {IL-SiO}_{2}@\hbox {MNP}\)) is prepared by the functionalization of \(\hbox {SiO}_{2}@\hbox {MNP}\) by 1-butyl-3-(3-trimethoxypropyl)-1H-imidazol-3-ium chloride as the IL moiety. The catalyst is characterized by transmission electron microscopy, scanning electron microscope, vibrating sample magnetometer, dynamic light scattering and Fourier transform infrared spectroscopy. \(\hbox {IL-SiO}_{2}@\hbox {MNP}\) showed good activity in the synthesis of 6H-chromeno[4,3-b]quinolin-6-one derivatives via multicomponent reaction of 4-hydroxycoumarin, anilines and benzaldehydes. The nanocatalyst is magnetically separable and easily recoverable and showed successful activity up to 10 runs.     

Promoting the Range and Range Resolution of a LIDAR (DIAL) System Using a Suitable Pinhole Plasma Shutter

Pulsed transversely exited atmospheric (TEA) CO₂ lasers, employed extensively in various applications such as light detection and ranging (LIDAR), have a pulse duration of about a microsecond due totheir nitrogen tail. In order to promote the measurement accuracy and the mean power of the laser pulse, the pulse duration should be shortened. In this research, we present the details of making a passive pinhole plasma shutter for a LIDAR (DIAL) system, which shortens the pulse duration of CO₂ lasers from 1.5 μs to 25 ns in air at atmospheric pressure. This instrument increases the range resolution of the LIDAR system from 225 to 3.75 m. Also we show the results of investigation of the clipped pulse duration of the microsecond CO₂ laser pulse using aluminum and copper pinhole metal targets with different pinhole diameters (1.5 and 1.8 mm) and at various laser output energies (338 and 309 mJ). Our experimental results show that the aluminum pinhole is more suitable than the copper pinhole for shortening the nitrogen tail of the CO₂ laser pulse with a larger output average power. Thus, the range of the LIDAR system, which is proportional to the logarithm of the output pulse power, is increased.     

A relation between the Laplacian and signless Laplacian eigenvalues of a graph

Let G be a graph of order n such that \(\sum_{i=0}^{n}(-1)^{i}a_{i}\lambda^{n-i}\) and \(\sum_{i=0}^{n}(-1)^{i}b_{i}\lambda^{n-i}\) are the characteristic polynomials of the signless Laplacian and the Laplacian matrices of G, respectively. We show that a _i ≥b _i for i=0,1,…,n. As a consequence, we prove that for any α, 0<α≤1, if q ₁,…,q _n and μ ₁,…,μ _n are the signless Laplacian and the Laplacian eigenvalues of G, respectively, then \(q_{1}^{\alpha}+\cdots+q_{n}^{\alpha}\geq\mu_{1}^{\alpha}+\cdots+\mu _{n}^{\alpha}\).     

Dynamic shortest path problems with time-varying costs

This paper concerns the problem of finding shortest paths from one node to all other nodes in networks for which arc costs can vary with time, each arc has a transit time, and parking with a corresponding time-varying cost is allowed at the nodes. The transit times can also take negative values. A general labeling method, as well as several implementations, are presented for finding shortest paths and detecting negative cycles under the assumption that arc traversal costs are piecewise linear and node parking costs are piecewise constant.     

Ciprofloxacin-functionalized magnetic silica nanoparticles: as a reusable catalyst for the synthesis of 1H-chromeno[2,3-d]pyrimidine-5-carboxamides and imidazo[1,2-a]pyridines

Molecular Diversity - In this research, synthesis and characterization of new surface-functionalized magnetic silica nanoparticles are reported. The magnetic silica nanoparticle was synthesized by...     

Mapping of Shape Invariant Potentials by the Point Canonical Transformation

In this paper by using the method of point canonical transformation we find that the Coulomb and Kratzer potentials can be mapped to the Morse potential. Then we show that the Pöschl-Teller potential type I belongs to the same subclass of shape invariant potentials as Hulthén potential. Also we show that the shape-invariant algebra for Coulomb, Kratzer, and Morse potentials is SU(1,1), while the shape-invariant algebra for Pöschl-Teller type I and Hulthén is SU(2).     

Cabibbo angle and quark masses in a four-quark model of quantum flavordynamics

The Cabibbo angle is related through spontaneous symmetry breaking to the masses of the light quarks in an illustrative model of quantum flavordynamics based on the SU_2L × SU_2R × U₁ flavor gauge group and on four quark flavors. The agreement with experiment is quite good.     

Component and system active redundancies for coherent systems with dependent components

The prevailing engineering principle that redundancy at the component level is superior to redundancy at the system level is generalized to coherent systems with dependent components. Sufficient (and necessary) conditions are presented to compare component and system redundancies by means of the usual stochastic, hazard rate, reversed hazard rate, and likelihood ratio orderings. Explicit numerical examples are provided to illustrate the theoretical findings. Some related results in the literature are generalized and extended. Copyright © 2017 John Wiley & Sons, Ltd.     

Synthesis,Antioxidant, and Antimicrobial Activity of Novel Hydrazones,Arylidenes, and Heterocycles Using 3,5-Diphenylcyclohex-2-en-1-one

Russian Journal of General Chemistry - Reactions of 3,5-diphenylcyclohex-2-en-1-one (1) with several chemical reagents have led to a variety of novel biologically active hydrazones, arylidene...     

Application of anodized edge-plane pyrolytic graphite electrode for analysis of clindamycin in pharmaceutical formulations and human urine samples

Different graphitic carbon-based electrode materials were evaluated for direct electro-oxidation of clindamycin and electroanalytical parameters such as sensitivity, residual background current, and signal-tobackground current ratio were compared to select the best one for the clindamycin electroanalysis. Such electrode materials include glassy carbon, carbon paste, pyrolytic graphite (edge-plane and basal-plane), carbon nanotube, reduced graphene oxide, and carbon black. The edge-plane pyrolytic graphite electrode after a simple and fast electrochemical pretreatment showed superior performance compared with the other carbon electrodes. Raman and Fourier transform infrared spectroscopy were employed to analyze the surface microstructure and chemical bonding of the carbon materials and scanning electron microscopy was used to study their surface morphologic features. The applicability of the electrochemically activated edge-plane pyrolytic graphite electrode for the determination of clindamycin in pharmaceutical formulations and human urine samples was evaluated.