Supported N-propylsulfamic acid on magnetic nanoparticles used as recoverable and recyclable catalyst for the synthesis of 2, 3-dihydroquinazolin-4(1H)-ones in water

An efficient and eco-friendly method is reported for the synthesis of 2-substituted-2,3-dihydroquinazolin -4（1 H）-ones from direct cyclocondensation of anthranilamide with aldehydes and ketones using N-propylsulfamic acid supported onto magnetic Fe₃O₄ nanoparticles（MNPs-PSA） as a recoverable and recyclable nanocatalyst in good to excellent yields in water at 70℃.The catalyst was readily separated using an external magnet and reusable without significant loss of their catalytic efficiency.     

Twist-grain boundary phase induced by Au nanoparticles in a chiral liquid crystal host

We report on the stabilisation of the liquid-crystalline, twist-grain boundary A (TGB_A) phase in mixtures of a chiral liquid crystal and surface-functionalised spherical Au nanoparticles (NPs) of 10 nm diameter. The results, obtained by calorimetric, optical, small-angle X-ray and plasmon resonance measurements, demonstrate that a TGB_A phase, which is metastable for the pure liquid crystal host, can be effectively stabilised for a 3 K range in the presence of NPs. Moreover, the role of NPs size on the TGB_A stabilisation is briefly discussed.     

Electrochemical Detection of Thioether‐Based Fluorosurfactants in Aqueous Film‐Forming Foam (AFFF)

Using cyclic voltammetry (CV) and impedance (IMP), we report a simple approach to detect new fluorosurfactant ingredient formulated in aqueous film‐forming foam (AFFF), specifically the thioether‐based one. First, we employ ion chromatography (IC) to identify all possible elements with the help of chemical oxidation and infrared spectrum (IR) to identify all possible functional groups. We thus propose a possible thioether‐based molecular structure of fluorosurfactant formulated in AFFF. By studying the self‐assembled monolayer (SAM) formed on gold (Au) surface via thio‐Au bond, we establish a relationship between the SAM density and the amount of the thioether‐based fluorosurfactant for the AFFF detection. Solid phase extraction (SPE) and nanoporous Au electrode are employed to enhance the sensitivity. Consequently, a detection limit of 10 ppb (v/v) has been achieved for AFFF‐spiked tap water sample.     

Gold Nanoparticles Supported on Mesoporous Titania Thin Films with High Loading as a CO Oxidation Catalyst

In the present work, 2.4 nm gold nanoparticles (Au NPs) are uniformly dispersed on mesoporous titania thin films which are structurally tuned by controlling the calcination temperature. The gold content of the catalyst is as high as 27.8 wt %. To our knowledge, such a high loading of Au NPs with good dispersity has not been reported until now. Furthermore, the reaction rate of the gold particles is enhanced by one order of magnitude when supported on mesoporous titania compared to non‐porous titania. This significant improvement can be explained by an increase in the diffusivity of the substrate due to the presence of mesopores, the resistance to agglomeration, and improved oxygen activation.     

A facile approach to prepare water-soluble magnetic metal (oxide) frameworks based on Na,Ca alginate and maghemite

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Optimized Synthesis of Silver Nanoparticles by Factorial Design with Application for the Determination of Melamine in Milk

A colorimetric method based on silver nanoparticles was developed for the determination of melamine in milk. Silver nanoparticles were synthesized without any stabilizer, using sodium borohydride as the reducing agent. Optimization of the variables for the formation of the nanoparticles was performed by factorial design, resulting in stable colloidal silver nanoparticles with a mean diameter of 14.0?±?2.7?nm. Spectrophotometric measurements performed at 475?nm showed a linear range from 0.033 to 1.50?mg?L^?1 of melamine with limits of detection and quantification of 0.009 and 0.031?mg?L^?1, respectively. The method provided highly sensitive determination of melamine in milk.     

DYE SENSITIZED TITANIA PHOTOVOLTAIC CELLS ON FLEXIBLE SUBSTRATES—CONCEPT TO COMMERCIALIZATION

ABSTRACT

Methods have been found for sintering titania nanoparticles at low temperature, e.g., <150°C, and for rapid sensitization of the sintered particles. This discovery means that dye-sensitized, titania solar cells can be made on flexible substrates, such as poly(ethylene terephthalate), in a continuous roll-to-roll manufacturing process. The ability to produce solar cells in a continuous fashion should substantially lower the cost of the cells compared to batch processed, on-glass cells. The combined attributes of spectral sensitivity, flexibility, light weight, impact resistance and low cost should find utility a variety of handheld appliances in both indoor and outdoor situations. In its most advanced state of development, this technology would find application in off-grid power generation and thus provide the opportunity of bringing solar generated electricity to rural areas of the world.     

Influence of High Peroxide Concentration on the Mechanical Properties of Cross-Linked Low Density Polyethylene

In this paper are presented the static and dynamic mechanical investigation of chemically cross-linked low density polyethylene (XLPE) prepared in our laboratory. This polymer has been tested mechanically at different frequencies, amplitudes, and temperatures as a function of cross-link density which is indicated to some extent by the amount of peroxide used in the cross-linking. The main findings can be described as follows: mechanical damping in XLPE at the α-relaxation point as a function of peroxide concentration is different for shear and compression modes of deformation. Moreover, the dynamic investigation at very small amplitudes indicated two relatively rigid structures. One structure at low concentration of peroxide is attributed to excessive crystallinity; the other one at the high peroxide concentration is probably due to the very regular and perfect polyethylene network. These two interesting structures are not detected by dynamical testing with large amplitudes. As far as Young's modulus as a function of peroxide concentration is concerned, we conclude that in this polymer this factor does not depend on the crystallinity but on changes of the so-called hard amorphous phase. These findings are consistent with our previous structural investigation.