A simple and cost effective sol–gel process for producing vanadium dioxide thin films was developed via thermolysis of V2O5·nH2O (n≈2) VV precursors prepared by dissolving vanadium powder or V2O5 powder in 30% hydrogen peroxide solutions. After spin-coating on fused silica substrates and annealing at 750°C in vacuum, without any intermediate gas reducing step, the major phase VO2(M, monoclinic phase) was found in both of the films based on V–H2O2 and V2O5–H2O2 precursor, exhibiting large transmittance changes (>40%) in the IR region (>2000nm) and small hysteresis loop width (<5°C) which were comparable to reported epitaxial VO2 films. The two films have similar metal-to-insulator transition temperature τC=62.5°C, lower than the classical value of 68°C for VO2 thin films. In addition, the method enables simple doping, as found for 0.56at.% W-doped VO2 films. This intrinsically simple solution process followed by one-step annealing makes it potentially useful in smart window applications.
Chemical welding of oppositely charged dissimilar metal chalcogenide nanomaterials is reported to produce a quaternary metal chalcogenide. CuSe and In2S3 nanoparticles were synthesized with opposite surface charges by stabilizing with polyacrylic acid and polydiallyldimethylammonium chloride. Upon mixing these nanoparticles at room temperature, the electrostatic attraction induced coalescence of these nanoparticles and led to the formation of CuInSxSe1-x nanoparticles.
Pesticides are an essential tool in integrated pest management. Nanopermethrin was prepared by solvent evaporation from an oil-in-water volatile microemulsion. The efficacy of the formulated nanopermethrin was tested against Aedes aegypti and the results compared to those of regular, microparticular permethrin. The 24 h LC50 for nanopermethrin and permethrin was found to be 0.0063 and 0.0199 mg/L, respectively. The formulated nanopermethrin was tested for toxicity against non-target organisms. Nanopermethrin did not show antibacterial activity against Escherichia coli (ATCC 13534 and 25922) or against Bacillus subtilis. Phytotoxicity studies of nanopermethrin to the seeds of Lycopersicum esculentum, Cucumis sativus, and Zea mays showed no restraint in root length and germination percentage. In the Allium cepa test, regular microparticular permethrin treatment of 0.13 mg/L showed a mitotic index (MI) of 46.8 % and chromosomal aberration of 0.6 %, which was statistically significant (p < 0.05) compared to control. No significant differences were observed in 0.13 mg/L nanopermethrin exposure as compared to control (MI of 52.0 and 55.03 % and chromosomal aberration of 0.2 and 0 %, respectively). It was concluded that formulated nanopermethrin can be used as a safe and effectual alternative to commercially available permethrin formulation in agricultural practices.
The main objective of this study was to form nanoparticles of a model hydrophobic drug, celecoxib, from a volatile microemulsion stabilized by a bile salt derivative. Nanoparticles were obtained by conversion of the microemulsion nanodroplets with the dissolved drug into solid nanometric particles. The use of bile salt derivatives as the surfactants for the formation of a microemulsion enabled significantly higher loading of the drug in both the microemulsion and nanoparticles, compared with the native bile salt. In addition, superior stability of the particles was achieved with the bile salt derivatives, and drug crystallization was inhibited. Interestingly, differences in particle stability and crystallization inhibition were observed between two bile salt derivatives differing only by one hydroxyl group on the bile salt backbone, indicating the delicate balance of interactions in the system. For one of the derivatives, upon dispersion of the nanoparticles in water, they spontaneously arranged into well-defined elongated nanometric tubules as detected and attested by cryo-TEM. It was found that the drug present in nanoparticles induces formation of the nanotubes.
Vanadium dioxide is an intriguing candidate for use in intelligent devices such as sensors, magnetic refrigeration and particularly as solar modulating smart window materials. A facile sol-gel route is developed to produce pure VO2 with different nanostructures in a CO2 atmosphere. It was found that the nanoporous structures demonstrated a 16% increase in the luminous transmittance (T-lum) (from 20% to 36%) compared with the vacuum results, while large supercooling effects of up to 30 degrees C have been observed in zero-dimensional structures.
A self-assembled polymer of linear polyethylenimine (LPEI) on indium tin oxide (ITO) is found to stabilize the titanium-doped vanadium oxide film. After modification by LPEI, the oxide film shows good cycling stability, and sustains over 1500 cycles in a three-electrode system, a remarkable improvement compared to that without LPEI modification.
3D conductors are developed by inkjet printing a UV curable ink composed of oil-in-water emulsion combined with a dispersion of silver nanoparticles. Upon UV radiation by LED light the droplets immediately polymerize and form solid structures with embedded silver nanoparticles. The unique composition of the new ink enables sintering of the silver nanoparticles at room temperature by contact with NaCl solution, leading to a conductivity of 1.9 × 106 S m−1 while maintaining the 3D structure. The aspect ratio for photo-polymerized printed lines is more than 10 times larger than that of non-irradiated lines. The emulsion–dispersion new inks are potential materials for 3D fabrication of conductors and other functional materials in printed electronics
Pure phase Zn2GeO4 nanowires (NWs) were grown by the chemical vapor transport method on p-GaN: Mg/Al2O3 substrate. The as grown Zn2GeO4 NWs exhibited n-type characteristic due to native defects and formed a p-n heterojunction with the p-GaN substrate. The unique energy level of Zn2GeO4 NWs promotes electron injection into GaN active region while suppressing hole injection into Zn2GeO4 NWs. The device exhibited an emission centered at 426 nm and a low turn-on voltage around 4 V. Zn2GeO4 NWs are first reported in this paper as promising electron transport and injection material for electroluminescent devices.
The present invention provides particles comprising either a water-sol. polymer or a phospholipid, wherein at least one near-IR (NIR) fluorescent probe and optionally at least one active agent such as a targeting moiety, capable of selectively recognizing a particular cellular marker, are non-covalently bound to the outer surface of the particles. Pharmaceutical compns. comprising these particles may be used, inter alia, for detection and treatment of tumors in the gastrointestinal tract. Anti-CEA-FITC-labeled indocyanine green (ICG)-adsorbed Eudragit RS-casein sodium salt polycationic nanoparticles were prepd. and used for in vivo specific recognition in and imaging of colons of LS174T tumor-bearing mice. Well identified LS174T tumors were successfully marked by the nanoparticles. [on SciFinder(R)]
A liq. coloring compn. comprises a coffee soln. or coffee ext. and an ink vehicle. The coloring compn. (composed of edible components) is suitable for use as an ink in a non-impact printing device, including an ink jet type printer. Thus, an ink formulation may include 89.9% coffee conc., 5% propylene glycol, 5% glycerol, and 0.1% Tween 80. A process for applying a design to a food substrate includes use of a non-impact printing device, in which the ink cartridge or external container contains this coloring compn. [on SciFinder(R)]
The invention provides a process for forming highly ordered, conductive and transparent patterns on flexible heat-sensitive surfaces. The invention relates to sintering nanoparticles at room temp. Patterning is done by a patterning device and the self-assembly of the nanoparticles. [on SciFinder(R)]
This study presents a method for one-step formation ofpoly(ethyleneoxide) nanofibers incorporating nanoparticles of a poorly water-solublecompound. Using the new method reported here, nanofiberânanoparticlecomposites are fabricated in one step by electrospinning of an oil-in-watermicroemulsion, in which a model material, propylparaben, has beendissolved within the volatile dispersed phase in the presence of ahigh-molecular-weight polymer. The approach is based on nanoscaleconfinement to the dispersed phase of an oil-in-water microemulsionwith a volatile oil phase, in which the poorly water-soluble materialsare dissolved. Thus, when the thermodynamically stable oil-in-watermicroemulsion is combined with the rapid evaporation of solvent inherentin the electrospinning process, the droplets are converted into organicnanoparticles embedded within a polymeric nanofiber. In addition topossessing process simplicity, this method exhibits a very high percentageof nanoparticle loading with desirable active material properties.Specifically, the diameter of the nanofibers is in the range of 60â185nm, and propylparaben exists within the nanofiber as nanocrystalsof 30â120 nm. These dimensions suggest that the nanofiberânanocrystalcomposites could serve as a delivery system for water-insoluble materials. [ABSTRACT FROM AUTHOR]Copyright of Langmuir is the property of American Chemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)