One-Pot Microwave-Assisted Synthesis of 3,4-Disubstituted 2-Quinolinones

An improved one-pot synthesis of 3,4-disubstituted 2-quinolinones is described. The condensation of substituted 2-aminobenzophenone (or 2-aminophenyl alkyl ketone) with acid chlorides was carried out in the presence of triethylamine (or NaH) under microwave reaction conditions (150oC, 200 psi). The reactions were completed within minutes to produce 2-quinolinones in moderate to excellent yields and good purities.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Production,purification and characterisation of a chitosanase from Bacillus cereus

In the present work, a chitosanase was induced from a squid pen powder-containing Bacillus cereus TKU031 medium, and the addition of 0.05 % (w/v) boric acid or sodium tetraborate resulted in 195 and 177 % enhancement, respectively, in TKU031 chitosanase production. The purified TKU031 chitosanase exhibited optimum activity at pH 5 and 50 °C and was stable at pH 5–9 and <50 °C. The TKU031 chitosanase that was used for chitooligomers preparation was studied. The enzyme products revealed various chitooligomers with different degrees of polymerisation from 3 to 8, as determined by a MALDI-TOF–mass spectrometer, confirming the endo-type nature of the TKU031 chitosanase.     

Versatile Synthetic Strategy for Coating Upconverting Nanoparticles with Polymer Shells through Localized Photopolymerization by Using the Particles as Internal Light Sources

We present a straightforward and generic strategy for coating upconverting nanoparticles (UCPs) with polymer shells for their protection, functionalization, conjugation, and for biocompatibility. UCPs are attracting much attention for their potential use as fluorescent labels in biological applications. However, they are hydrophobic and non‐compatible with aqueous media; thus prior surface modification is essential. Our method uses the internal UV or visible light emitted from UCPs upon photoexcitation with near‐infrared radiation, to locally photopolymerize a thin polymer shell around the UCPs. In this way, a large variety of monomers with different chemical functionalities can be incorporated. If required, a second layer can be added on top of the first. Our method can provide a large spectrum of surface functional groups rapidly and in one pot, hence offering a platform for the preparation of libraries of functional polymer‐encapsulated UCPs for applications in bioassays, biosensing, optical imaging, and theranostics.     

Platinum and Palladium Nanotubes Based on Genetically Engineered Elastin–Mimetic Fusion Protein‐Fiber Templates: Synthesis and Application in Lithium‐O2 Batteries

The coupling of proteins with self‐assembly properties and proteins that are capable of recognizing and mineralizing specific inorganic species is a promising strategy for the synthesis of nanoscale materials with controllable morphology and functionality. Herein, GPG‐AG3 protein fibers with both of these properties were constructed and served as templates for the synthesis of Pt and Pd nanotubes. The protein fibers of assembled GPG‐AG3 were more than 10 μm long and had diameters of 20–50 nm. The as‐synthesized Pt and Pd nanotubes were composed of dense layers of ～3–5 nm Pt and Pd nanoparticles. When tested as cathodes in lithium‐O₂ batteries, the porous Pt nanotubes showed low charge potentials of 3.8 V, with round‐trip efficiencies of about 65 % at a current density of 100 mA g^?1.     

On contraction of nonlinear difference equations with time‐varying delays

General nonlinear difference equations with time‐varying delays are considered. Explicit criteria for contraction of such equations are presented. Then some simple sufficient conditions for global exponential stability of equilibria and for stability of invariant sets are derived. Furthermore, explicit criteria for existence, uniqueness and global exponential stability of periodic solutions are derived. Finally, the obtained results are applied to time‐varying discrete‐time neural networks with delay.     

Hardy–Rellich identities with Bessel pairs

Archiv der Mathematik - We prove an identity that implies the classical Rellich inequality as well as several improved versions of Rellich type inequalities. Moreover, our equality gives a simple...     

Polymeric Heterogeneous Catalysts of Transition‐Metal Oxides: Surface Characterization,Physicomechanical Properties,and Catalytic Activity

We investigate the physicomechanical properties of polymeric heterogeneous catalysts of transition‐metal oxides, specifically, the specific surface area, elongation at break, breaking strength, specific electrical resistance, and volume resistivity. Digital microscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and energy‐dispersive analysis are used to study the surfaces of the catalysts. The experimental results show that polymeric heterogeneous catalysts of transition‐metal oxides exhibit high stability and can maintain their catalytic activity under extreme reaction conditions for long‐term use. The oxidation mechanism of sulfur‐containing compounds in the presence of polymeric heterogeneous catalysts of transition‐metal oxides is confirmed. Microstructural characterization of the catalysts is performed by using X‐ray computed tomography. The activity of various catalysts in the oxidation of sulfur‐containing compounds is determined. We demonstrate the potential application of polymeric heterogeneous catalysts of transition‐metal oxides in industrial wastewater treatment.     

Gold(I) Complexes Nuclearity in Constrained Ferrocenyl Diphosphines: Dramatic Effect in Gold‐Catalyzed Enyne Cycloisomerization

Di‐tert‐butylated‐bis(phosphino)ferrocene ligands bearing phosphino substituents R (R=phenyl, cyclohexyl, iso‐propyl, mesityl, or furyl) allow tuning the selective formation of Au(I) halide complexes. Thus, dinuclear linear two‐coordinate, but also rare mononuclear trigonal three‐coordinate and tetrahedral four‐coordinate complexes were formed upon tuning of the conditions. Both Au(I) chloride and rarer Au(I) iodide complexes were synthesized, and their X‐ray diffraction analysis are reported. The significance of the control of structure and nuclearity in Au(I) complexes is further illustrated herein by its strong effect on the efficiency and selectivity of gold‐catalysed cycloisomerization. Cationic linear digold(I) bis(dicyclohexylphosphino) ferrocenes outperform other catalysts in the demanding regioselective cycloisomerization of enyne sulphonamides into cyclohexadienes. Conversely, tetrahedral and trigonal cationic monogold(I) complexes were found incompetent for enyne cycloaddition. We used the two‐coordinate linear electron‐rich Au(I) complex 2 b (R=Cy) to extend the scope of selective intramolecular cycloaddition of different 1,6‐enyne sulfonylamines with high activity and excellent selectivity to the endo cyclohexadiene products.     

Chemical Antibody Mimics Inhibit Cadherin‐Mediated Cell–Cell Adhesion: A Promising Strategy for Cancer Therapy

One of the most promising strategies to treat cancer is the use of therapeutic antibodies that disrupt cell–cell adhesion mediated by dysregulated cadherins. The principal site where cell–cell adhesion occurs encompasses Trp2 found at the N‐terminal region of the protein. Herein, we employed the naturally exposed highly conserved peptide Asp1‐Trp2‐Val3‐Ile4‐Pro5‐Pro6‐Ile7, as epitope to prepare molecularly imprinted polymer nanoparticles (MIP‐NPs) to recognize cadherins. Since MIP‐NPs target the site responsible for adhesion, they were more potent than commercially available therapeutic antibodies for inhibiting cell–cell adhesion in cell aggregation assays, and for completely disrupting three‐dimensional tumor spheroids as well as inhibiting invasion of HeLa cells. These biocompatible supramolecular anti‐adhesives may potentially be used as immunotherapeutic or sensitizing agents to enhance antitumor effects of chemotherapy.     

One-pot synthesis of a novel magnetic activated carbon/clay composite for removal of heavy metals from aqueous solution

Abstract

In the present work, a novel composite consisting of magnetite, activated carbon from spent coffee grounds and natural clay (MACCC) was prepared by a one-pot synthesis method via a simultaneous activation and magnetization processes. Various techniques (XRD, FTIR, SEM, TEM, EDX, BET) were utilized to characterize the synthesized composite before utilizing it as an adsorbent for removal of Cu(II), Ni(II) and Pb(II) ions from aqueous solutions. Conditions for removal of heavy metals were thoroughly optimized as 25?°C, pH of 5.5, adsorbent dosage of 2?g L^?1, and a contact time of 60?min. Three models of pseudo first-, second-order and intraparticle diffusion as well as three models of Langmuir, Freundlich, and Temkin were used to analyze kinetics and isotherms of the adsorption process. Thermodynamics was discussed completely. Regeneration and recyclability of the adsorbent were also evaluated. Based on the analysis of experimental results, a possible adsorption mechanism of heavy metals onto the synthesized composite was proposed. The maximum capacities caculated from Langmuir model followed the order of Pb(II) > Cu(II) > Ni(II) as 143.56, 96.16 and 84.86?mg·g^?1, respectively. The overall results indicated that MACCC is a potential adsorbent for removal of toxic Pb(II), Cu(II) and Ni(II) ions from wastewater due to simple preparation, high removal efficiency and good recyclability.