The influence of the ethanol-water molar ratio in the precursor solution on morphology and photocatalytic activity of pyrolytic ZnO films

Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol-water molar ratio, gamma, in the precursor solution was varied from 0 to 0.92. The deposition temperature and the pH of the precursor solution were kept at 350 degrees C and 4.5, respectively. X-ray diffraction patterns revealed that films were zincitelike with a grain size depending on the ethanol-water molar ratio in the precursor solution. The interference pattern obtained during film deposition was used to monitor the film roughness; it was found that this is related with those results of surfaces and optical analysis obtained by scanning electron microscopy and spectrophotometric measurements, respectively. The morphology of the ZnO films obtained from gamma equal to either 0 or 0.92 are dense with agglomerates uniformly distributed, whereas the films obtained from gamma equal to either 0.03 or 0.06 are very rough with irregular agglomerates. The films obtained from gamma equal to 0.12, 0.18 and 0.31 are rough. Photoelectrocatalytic results indicated that there is a correlation of the partial molar volume of ethanol with respect to water in the spraying solution, with the photocatalytic efficiency of the ZnO films. We found that the maximum photodegradation of methyl orange in the solution occurs using ZnO films obtained with gamma = 0.12.     

Phase evolution of sol-gel CaO-ZrO2 using sulfuric acid as hydrolysis catalyst

Several compositions in the CaO-ZrO₂ system were synthesized from zirconium n-butoxide and calcium methoxide, by the sol-gel method. Hydrolysis and gelation occurred at pH 3, using H₂SO₄ as hydrolysis catalyst. Fresh gels were annealed in air at 100 to 900°C, in 100°C steps every 20 h, for a total annealing time of 140 h. Analysis by X-ray diffraction showed the formation of hydrated calcium sulfate together with amorphous zirconia up to 400°C. At the ZrO₂ rich-end, tetragonal and monoclinic zirconia solid solutions were stabilized in the presence of Ca ions. When 20 and 30 wt% of CaO were added, cubic zirconia and CaZrO₃ solid solutions were observed above 700°C. At the CaO rich-end, the coexistence of calcium carbonate polymorphs as vaterite and calcite were observed. Anhydrite was present across the entire range of compositions studied from 300 to 900°C.     

Sensitive determination of acidic drugs and triclosan in surface and wastewater by ion-pair reverse-phase liquid chromatography/tandem mass spectrometry

A new method is presented for the determination of 12 acidic pharmaceuticals (non-steroidal anti-inflammatory drugs and bezafibrate), including two metabolites from aqueous samples, together with triclosan as a personal care product. Ion-pair liquid chromatography (IP-LC) with electrospray ionisation tandem mass spectrometry (ESI-MS) in the negative ion mode was employed. The ion-pairing agent (tri-n-butylamine) increased the signal intensity for all acidic analytes and detection limits of 6-200 ng/L were obtained by multiple reaction monitoring. This allows analysis of wastewater samples by direct injection into the LC/MS system without the need for a preceding enrichment step. When combined with a solid-phase extraction (SPE) step, limits of quantification between 0.15 and 11 ng/L were obtained from 100-mL sample volumes, which is adequate for most applications. The occurrence of matrix effects was studied and standard addition was required for reliable quantification after SPE from wastewater. The method was finally applied to surface and wastewaters, with analyte concentrations ranging from below the detection limit up to 5.5 microg/L.     

Water‐dispersive PLA‐based materials: from reactive melt processing to properties

Melt blending of poly(l ‐lactide) (PLLA) and water‐soluble polymers was carried out through reactive melt processing with the objective to prepare water‐dispersible PLLA‐based materials. For this purpose, both polyvinyl alcohol (PVOH) and hydroxyethyl cellulose (HEC) were considered. Prior to melt blending, the preparation of plasticized PVOH and plasticized HEC was performed. The so‐obtained blends have been characterized in terms of morphology and thermomechanical properties. The morphological analysis evidenced the possibility to prepare co‐continuous PLLA/plasticized HEC blends. Nevertheless, their low melt strength did not allow producing monofilaments by melt spinning. Thus, PVOH was considered as an alternative to HEC. The results showed that using maleic anhydride‐grafted polylactide as a compatibilizer for PLLA/plasticized PVOH 40/60 (w/w) blends allowed preparing co‐continuous blends leading to tough monofilaments with high ultimate elongation. Moreover, the assessment of the water dispersiveness revealed that the monofilaments readily swelled in water and started to break up after 30 min. A full fragmentation of the monofilaments was observed within 1 hr. Copyright © 2015 John Wiley & Sons, Ltd.     

Shock temperature measurement using neutron resonance spectroscopy

We report a direct measurement of temperature in a shocked metal using Doppler broadening of neutron resonances. The 21.1-eV resonance in 182W was used to measure the temperature in molybdenum shocked to approximately 63 GPa. An explosively launched aluminum flyer produced a planar shock in a molybdenum target that contained a 1-mm thick layer doped with 1.7 at. %(182)W. A single neutron pulse, containing resonant neutrons of less than 1 mus duration, probed the shocked material. Fits to the neutron time-of-flight data were used to determine the temperature of the shocked molybdenum.     

Miscibility of poly(ethylene oxide) with poly(N-vinyl pyrrolidone): DMTA and DTA studies

Dynamic mechanical thermal analysis and calorimetric studies are reported on blends of poly(ethylene oxide) (PEO) with poly(N-vinyl pyrrolidone) (PVP) between 80% and 40% PEO. DMTA curves show a peak corresponding to a phase of pure PEO and another peak which can be attributed to blended material. The calorimetric analysis shows an appreciable melting point depression and a marked decrease in the crystallization rate as the PVP content increases. The melting point depression follows the Nishi-Wang equation, giving an interaction parameter of ?0.50. These studies suggest the existence of microphases in the blend.