Laser‐Induced Self‐Assembled Nanostructures on Electron‐Transparent Substrates

Currently, one of the challenges in high‐resolution transmission electron microscopy (TEM) studies of nanomaterials is to make contamination‐free materials in a simple and time‐efficient way. Here, a method is demonstrated that combines nanosecond‐pulsed laser dewetting of thin films with a film float‐off technique to realize nanostructures (NSs) on electron‐transparent substrates in a robust and rapid manner. NSs of metal (Ag) and bimetals (AgCo, AuCo) ranging from 20 to 150 nm are synthesized on thin carbon film deposited on mica substrates. The NS/carbon system is subsequently transferred onto TEM grids by a float‐off process resulting from debonding of the carbon from mica due to their contrasting hydrophobic nature. This process enables the fabrication of different NSs on flexible and electron‐transparent substrates.     

Enhancement of optical conductivity in the ultra-violet region of Cs doped ZnO sol gel thin films

Nano crystalline cesium (Cs) doped ZnO thin films were deposited on glass substrate by sol gel spin coating method with 1–3 mol.% doping concentration and different annealing temperatures. The deposited films were characterized by X-ray diffraction (XRD), Hall Effect, Photoluminescence (PL) and UV–Visible studies. XRD measurements reveal that all the samples abound in the wurtzite structure with polycrystalline nature. An increase in crystalline size from 19.60 to 44.54 nm is observed with the increase of doping concentration. Electrical conductivity of Cs doped ZnO films were observed from Hall effect measurements and the maximum carrier concentration obtained is 7.35 × 10¹⁸ cm^?3. The near band emission (384 nm) peak intensity increases with the increase of Cs doping concentration and a maximum intensity 55,280 was observed for CZ3 film from PL spectrum. Also a low energy near infrared (NIR) emission peak centered at 1.62 eV appears for the Cs doped ZnO films. The average transmission of CZ film is 88 % and the absorption edge is red shifted with the increase of Cs doping concentration and also the optical conductivity increases in the UV region.     

Measurement of thermal constants of calcium chromite by Laser Flash method

Calcium chromite, CaCr₂O₄, was prepared and its purity and stoichiometry were ascertained by chemical analysis and X-ray diffraction methods. The thermal diffusivity, specific heat capacity and thermal conductivity of calcium chromite were measured by Laser Flash method using an Ulvac-Sinku Riko TC-3000 series instrument in the temperature range of 298 to 1100 K. The heat capacity data were utilised to calculate the thermodynamic parametersenthalpy increments, entropy increments and free energy increments—in the above temperature range.

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Zusammenfassung Kalziumchromit, CaCr₂O₄, wurde hergestellt und seine Reinheit und stöchiometrische Zusammensetzung mit Hilfe chemischer Analyse und Röntgendiffraktionsmethoden ermittelt. Anhand eines Ulyac-Sinku Riko TC-3000 Gerätes wurde mit Laser Flash Verfahren die Temperaturleitfähigkeit, die spezifische Wärmekapazität und die Wärmeleitfähigkeit von Kalziumchromit im Temperaturbereich 298–1100 K bestimmt. Die Wärmekapazitätsdaten wurden zur Berechnung der thermodynamischen Größen (Enthalpie-, Entropie-, Freie Energieänderung) in obigem Temperaturbereich benutzt.

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CaCr₂O₄, . , - TC-3000, 298–1100K , . , , .

     

CHARACTERIZATION OF RADICAL ADDUCTS FORMED DURING PHOTOCHEMICAL SPIN TRAPPING IN LIPOSOMES

There exists an urgent need to monitor radical reactions in biological membranes. With the exception of a few studies in model and natural membranes, most biological spin trapping reactions have been confined to homogeneous media. In the present work we have devised a methodology by which spin trapping reactions can be investigated in liposomes composed of a fully-saturated phospholipid, dimyristoylphosphatidylcholine. Using photochemical spin trapping, we have detected and characterized the formation and partitioning of spin adducts in liposomes. Benzophenone (a lipid-soluble photosensitizer) and benzoyl peroxide (a lipid-soluble radical initiator) have been used to generate free radicals from hydrogen donors during photolysis in liposomes. Both water-soluble and lipid-soluble spin traps have been used to trap the radicals.     

Voltammetric sensing of sulfamethoxazole using a glassy carbon electrode modified with a graphitic carbon nitride and zinc oxide nanocomposite

A voltammetric sensor is described for the determination the antibiotic sulfamethoxazole (SMZ). It is based on the use of a glassy carbon electrode (GCE) modified with a nanocomposite prepared from graphitic carbon nitride and zinc oxide (g-C₃N₄/ZnO). The nanorod-like ZnO nanostructure were synthesized sonochemically. The g-C₃N₄/ZnO nanocomposite was then prepared by mixing g-C₃N₄ with ZnO, followed by ultrasonication. The morphology and structure of the nanocomposite were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and transmission electron microscopy. Under the optimal conditions, the response of the electrode, typically measured between 0.8 and 0.9 V (vs. Ag/AgCl), increases linearly in the 20 nM to 1.1 mM SMZ concentration range, and the lower detection limit is 6.6 nM. This is better than that of many previously reported sensors for SMZ. The modified electrode is highly selective, well reproducible and maintains its activity for at least 4 weeks. It was applied to the determination of SMZ in spiked human blood serum samples in with satisfactory results.

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Graphical abstract Schematic presentation of the voltammetric sensor for sulfamethoxazole. It consists of a glassy carbon electrode modified with a nanocomposite prepared from graphitic carbon nitride (g-C₃N₄/ZnO) that was supported with zinc oxide nanorods.

     

Photopolymerization of 1,6‐hexanedioldiacrylate initiated by three‐component systems based on N‐arylphthalimides

Three‐component photoinitiators comprised of an N‐arylphthalimide, a diarylketone, and a tertiary amine were investigated for their initiation efficiency of acrylate polymerization. The use of an electron‐deficient N‐arylphthalimide resulted in a greater acrylate polymerization rate than an electron‐rich N‐arylphthalimide. Triplet energies of each N‐arylphthalimide, determined from their phosphorescence spectra, and the respective rate constants for triplet quenching by the N‐arylphthalimide derivatives (acquired via laser flash photolysis) indicated that an electron–proton transfer from an intermediate radical species to the N‐arylphthalimide (not energy transfer from triplet sensitization) is responsible for generating the initiating radicals under the conditions and species concentrations used for polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4009–4015, 2004     

Infrared and polarized Raman spectra of dixanthinium tetrachlorozincate single crystal

Single crystal dixanthinium tetrachlorozincate has been grown from dilute chloridric acid. Polarized Raman spectrum of the single crystalline sample, FT-Raman and FT-IR spectra of the polycrystalline samples have been examined and the bands assigned to the appropriate modes predicted by a factor group analysis for the space group Pmn2₁. The crystal structure has been confirmed by powder XRD measurements.