Design,Synthesis, and Antibacterial Evaluation of Some Novel 3′-(Phenylamino)-1′H-spiro[indoline-3,2′-quinazoline]-2,4′(3′H)-dione Derivatives

A combinatorial synthesis and evaluation of antibacterial activity against clinically isolated resistant strains of Gram-positive and Gram-negative bacteria of 3′-(phenylamino)-1′H-spiro[indoline-3,2′-quinazoline]-2,4′(3′H)-dione derivatives is described.     

Determination of copper,nickel, manganese and cadmium ions in aqueous samples by flame atomic absorption spectrometry after simultaneous coprecipitation with Co(OH)2

A separation-preconcentration procedure was developed for the determination of trace amounts of copper, nickel, manganese and cadmium ions in water samples by flame atomic absorption spectrometry after coprecipitation by Co(OH)₂ as a carrier without a chelating agent. The influence of the various analytical parameters such as pH, amount of carrier reagent, standing time, centrifugation rate and time, sample volume and matrix effects on the recovery of the analyte ions was studied. Under the specified experimental conditions the calibration curves for Ni(II) and Cu(II) were linear from 0.5 to 200 ng mL^?1 and for Mn(II) and Cd(II) from 0.5 to 250 and 0.3 to 80 ng mL^?1, respectively. The relative standard deviations for seven replicate determinations of a mixture of 40.0 ng mL^?1 of Cu(II), Ni(II), Mn(II) and 20 ng mL^?1 of Cd(II) in the original solution were 1.9%, 1.7%, 1.8% and 2.1%, respectively. The detection limits based on 3S_b/m for Cu(II), Ni(II), Mn(II) and Cd(II) in the original solution were 0.2, 0.2, 0.3 and 0.07 ng mL^?1, respectively. The limits of quantification based on 10S_b/m for Cu(II), Ni(II), Mn(II) and Cd(II) in the original solution were 6.7, 6.7, 10.0 and 2.3 ng mL^?1, respectively. The proposed method has been applied to the determination of trace amounts of the analyte ions in two certified reference materials (the National Institute for Environment Studies (NIES) No. 1 Pepperbush and NIES No. 7 Tea Leaves) and water samples and satisfactory results were obtained.     

Synthesis of Monospiro‐2‐amino‐4H‐pyran Derivatives Catalyzed by Propane‐1‐sulfonic Acid‐Modified Magnetic Hydroxyapatite Nanoparticles

Various monospiro‐2‐amino‐4H‐pyran derivatives have been synthesized in high yields (via three‐component coupling of ninhydrin or different isatins with malononitrile and 1,3‐dicarbonyl compounds) in the presence of catalytic amount of propane‐1‐sulfonic acid‐modified magnetic hydroxyapatite nanoparticles in H₂O. Due to easy magnetic removal of nanocatalyst and applying of H₂O as solvent, this protocol enhanced product purity, and promised economic as well as environmental benefits, exemplifying a waste‐free chemistry. More importantly, the catalyst could be easily recycled for more than five times without loss of activity.     

Ionic liquid-based dispersive liquid–liquid microextraction for the separation and preconcentration of lead in water samples prior to FAAS determination without chelating agent

In the present study, an environment-friendly sample preparation method termed ionic liquid-based dispersive liquid–liquid microextraction combined with flame atomic absorption spectrometry has been developed for the determination of Pb(II) ion in water samples prior to flame atomic absorption spectrometry determination. In this method, ionic liquid was used as an extraction solvent instead of the organic solvent used in the conventional dispersive liquid–liquid microextraction (DLLME) assay, and there is no need for a chelating agent. Several variables that may affect extraction efficiencies, including pH, the volume of ionic liquid, the type and volume of disperser solvent, salt addition, and the time for centrifugation and extraction were studied and optimised. Under the optimised conditions, the calibration curve exhibited linearity over the range of 20.0–1000.0 μg L^?1. The enrichment factor and the limit of detection based on 3S_b/m were 35.0 and 5.9 μg L^?1, respectively. Seven replicate determination of a solution containing of 100.0 μg L^?1 Pb(II) ions gave a relative standard deviation of ±2.1%. Finally, the feasibility of the proposed method for Pb(II) determination was assessed by the analysis of certi?ed reference material and various water samples and the satisfactory results were obtained.     

Development of a Novel Electrochemical Sensor Based on Functionalized Carbon Black for the Detection of Guanine Released from DNA Hydrolysis

In this work, we reported a new strategy based on DNA strands hydrolysis in combination with the employment of functionalized carbon black modified screen-printed electrode (f-CB/SPE) for guanine detection. Using glass microbeads as a solid substrate of ssDNA probe fixation, and under appropriate conditions of temperature, time, and hydrochloric acid concentration, DNA hydrolysis has been successfully used to release the guanine, allowing its oxidation at f-CB/SPE using differential pulse voltammetry. The selectivity was successfully tested with a non-complementary sequence, and a detection limit of 0.7 nM of the target DNA has been reached.     

Comprehensive Study of Free Radical Copolymerization Using a Monte Carlo Simulation Method, 1

Summary: In order to investigate the influence of reactivity ratios and initial feed composition on the microstructure of macromolecules in free radical copolymerization, a comprehensive study was carried out using a Monte Carlo simulation method. As a result, a new procedure was introduced to modify the works of others on the initiation step. The variation of the copolymer composition and the fashion of the arrangement of monomers in simulated chains were evaluated as a function of copolymerization parameters. The model was capable of monitoring any change in azeotropy as well as the magnitude and direction of composition drift from the azeotrope point. The maximum reachable conversion (MRC) was predicted for different combinations of initial feed compositions and reactivity ratios. According to the simulation results, a critical conversion where the macromolecules produced inherited the maximum allowed alternation was obtained for the reactivity ratios given.

Change of sequence distribution of simulated copolymer chains with conversion for various initial feed compositions on a triangular graph (r_A = 0.5, r_B = 0.9).     

Synthesis and characterization of a novel magnetic nano‐palladium Schiff base complex: application in cross‐coupling reactions

A novel and task‐specific nano‐magnetic Schiff base ligand with phosphate spacer using 2‐aminoethyl dihydrogen phosphate instead of usual coating agents, i.e. tetraethoxysilane and 3‐aminopropyltriethoxysilane, for coating of nano‐magnetic Fe₃O₄ is introduced. The nano‐magnetic Schiff base ligand with phosphate spacer as a novel catalyst was synthesized and fully characterized using infrared spectroscopy, X‐ray diffraction, scanning and transmission electron microscopies, thermogravimetry, derivative thermogravimetry, vibrating sample magnetometry, atomic force microscopy, X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray spectroscopy. The resulting task‐specific nano‐magnetic Schiff base ligand with phosphate spacer was successfully employed as a magnetite Pd nanoparticle‐supported catalyst for Sonogashira and Mizoroki–Heck C–C coupling reactions. To the best of our knowledge, this is the first report of the synthesis and applications of magnetic nanoparticles of Fe₃O₄@O₂PO₂(CH₂)₂NH₂ as a suitable spacer for the preparation of a designable Schiff base ligand and its corresponding Pd complex. So the present work can open up a new and promising insight in the course of rational design, synthesis and applications of various task‐specific magnetic nanoparticle complexes. Copyright © 2016 John Wiley & Sons, Ltd.     

Towards Understanding the Involvement of H+-ATPase in Programmed Cell Death of Psammosilene tunicoides after Oxalic Acid Application

Psammosilene tunicoides is a unique perennial medicinal plant species native to the Southwestern regions of China. Its wild population is rare and endangered due to over-excessive collection and extended growth (4–5 years). This research shows that H⁺-ATPase activity was a key factor for oxalate-inducing programmed cell death (PCD) of P. tunicoides suspension cells. Oxalic acid (OA) is an effective abiotic elicitor that enhances a plant cell’s resistance to environmental stress. However, the role of OA in this process remains to be mechanistically unveiled. The present study evaluated the role of OA-induced cell death using an inverted fluorescence microscope after staining with Evans blue, FDA, PI, and Rd123. OA-stimulated changes in K⁺ and Ca²⁺ trans-membrane flows using a patch-clamp method, together with OA modulation of H⁺-ATPase activity, were further examined. OA treatment increased cell death rate in a dosage-and duration-dependent manner. OA significantly decreased the mitochondria activity and damaged its electron transport chain. The OA treatment also decreased intracellular pH, while the FC increased the pH value. Simultaneously, NH₄Cl caused intracellular acidification. The OA treatment independently resulted in 90% and the FC led to 25% cell death rates. Consistently, the combined treatments caused a 31% cell death rate. Furthermore, treatment with EGTA caused a similar change in intracellular pH value to the La³⁺ and OA application. Combined results suggest that OA-caused cell death could be attributed to intracellular acidification and the involvement of OA in the influx of extracellular Ca²⁺, thereby leading to membrane depolarization. Here we explore the resistance mechanism of P. tunicoides cells against various stresses endowed by OA treatment.