Copper (II) Ions into Polyphosphazenes: Solid-Like Solution Behavior

Reaction of Cu(BF₄)₂ salt with the polymer [NP(OC₆H₄C(O)C–OC₆H₅)₂] _n (1) in THF affords three new polymers gels containing varied copper (II) ions contents, (2), (3), and (4). The nature of the copper (II) ions in the gel (2)–(4) was examined by IR spectroscopy, solid state ³¹P, ¹³C and ⁶³Cu NMR spectroscopy and EPR spectroscopy. Despite the copper content, the gels were insulators as measured by complex impedance spectroscopy. SEM images show a uniform distribution of the Cu (II) ions and a most porous morphology than those without copper polymer. TEM images show the formation of small aggregates being smallest for, gel (2) of about 200 nm. All the data suggest the Cu²⁺ centers behave as a solid dilute into the polyphosphazenes.     

Optical parameters of oxide films typically used in optical coating production

Wavelength dependencies of refractive indices of thin film materials differ for various deposition conditions, and it is practically impossible to attribute a single refractive index wavelength dependence to any typical thin film material. Besides objective reasons, differences in the optical parameters of thin films may also be connected with nonadequate choices of models and algorithms used for the processing of measurement data. The main goal of this paper is to present reliable wavelength dependencies of refractive indices of the most widely used slightly absorbing oxide thin film materials. These dependencies can be used by other researchers for comparison and verification of their own characterization results.     

Definition of roughness structures for superhydrophobic and hydrophilic optical coatings on glass

With specific modeling, measurement, and analysis procedures, it is possible to predict, define, and control roughness structures for tailored wetting properties of optical coatings. Examples are given for superhydrophobic and hydrophilic sol-gel layers on glass substrate.     

Blue pigment colors from wall painting churches in danger (Portugal 15th to 18th century): identification, diagnosis, and color evaluation

Samples of blue wall paint layers from selected 15th to 18th century religious mural paintings from southern Portugal (Alentejo) have been analyzed using a multi-analytical methodology involving the combination of in situ visible spectro-colorimetry with microanalytical techniques such as optical and scanning electron microscopy and Raman spectroscopy. In situ analyses and micro-sampling were carried out in nine different churches, many in an advanced state of deterioration. The objectives of this study were: (a) to identify and compare the pigments that were used in the blue paint layers across the Alentejo region and through time by analysis of the elemental and mineralogical composition and pictorial techniques, and (b) to correlate the data between the actual color of the paint layer and the state of conservation of the pigments. For the paintings dated from the 16th century forward, the results show a generalized use of smalt blue. To a lesser extent, natural azurite was used despite the geological richness of the region in copper and pyrite ores. In only one painting was an optical blue made of carbon black and lime found. The pigments, pure or mixed with red and yellow ochres, were coarsely ground and used in different concentrations to create three-dimensional effects. These parameters as well as the presence of iron oxides in underlayer paints influence the colorimetric coordinates in the more transparent smalt blue paint layers. The state of conservation of the pigments plays an important role in the alteration of the paint color. A clear example of this is the fading of the smalt blue in several paintings due to lixiviation processes.     

Deep ablation and depth profiling by laser-induced breakdown spectroscopy (LIBS) employing multi-pulse laser excitation: application to galvanized steel

The potential of a multi-pulse (MP) laser excitation scheme for deep stratigraphy of electrolytically galvanized steel using laser-induced breakdown spectrometry (LIBS) has been evaluated. For this purpose, a commercial electro-optically (EO) Q-switched Nd:YAG laser was employed, where by reducing the delay between the Q-switch opening and the flash lamp, a train of pulses (up to 11) separated by approximately 7.40 μs was generated during one lamp flashing. Plasma emission after each individual laser pulse of the MP sequence was detected by a spectrograph equipped with an intensified charge-coupled device (iCCD) detector. With MP excitation, the ablation efficiency was increased ten-fold on iron sample and 22.5-fold on zinc material with respect to dual-pulse or single-pulse excitation. The LIBS signal generated by MP excitation shows an analogous enhancement. Although the total energy per shot delivered to samples was only 60 mJ, it was possible using LIBS to measure the sample stratigraphy up to depths of 90 μm on zinc-coated steel sheets. A satisfactory agreement between the Zn thickness determined by the MP-LIBS system and data from the manufacturer has also been obtained.     

Atomically resolved surface structures of vapor deposited amorphous silicon-carbon alloys: An atomic force microscopy and spectroscopic study

Silicon carbide alloys are widely used in high-tech applications due to their interesting combination of chemical, mechanical and electronic properties. Growing thin films of this material in a simple and controlled way is a hot topic in modern material's science. In particular, the possibility to tailor the film properties just by tuning the deposition temperature would be an important progress. In the present work amorphous silicon-carbon alloys thin films have been deposited by electron beam sublimation of a poly-crystalline silicon carbide target in vacuum environment. The deposition temperature was varied from Room Temperature to about 1300 K. The resulting films were analyzed by means of Ultra High Vacuum-Atomic Force Microscopy (UHV-AFM) down to even atomic resolution. The observed features agree with literature data, e.g. interatomic bond lengths, as achieved by others methods, and the structural arrangements of silicon and carbon atoms as concluded from IR and Raman spectroscopy measurements carried out on the same samples. The results not only allow a correlation between film properties and deposition temperature but also support the notion of the UHV-AFM images of the amorphous surfaces being atomically resolved.     

CO sensing devices based on indium oxide nanoparticles prepared by laser ablation in water

A simple and effective solution route for synthesizing colloidal indium oxide (In₂O₃) nanocrystallites, i.e. laser ablation in liquid (LAL), is reported. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed the formation of In₂O₃ nanoparticles with a bimodal distribution, consisting mainly of particles of small diameters (2-5 nm). Sensor devices prepared by spraying directly the LAL colloidal solutions on interdigitated alumina substrates exhibited good sensing properties for the detection of CO at very low concentrations.     

Characterisation of Alpine lake sediments using multivariate statistical techniques

A recent type of receptor modelling technique the Positive Matrix Factorization (PMF) has been applied to a geochemical dataset obtained by XRF analysis on sediments from 11 alpine lakes located in Italy. Also, two usual pattern recognition techniques, Principal Component Analysis (PCA) and Cluster Analysis (CA), were investigated. Four interpretable factors were identified through PMF analysis, in connection with the mineralogical/chemical features of lake sediments in the catchment areas: phosphate and sulphur source, carbonates, silicates and heavy metal-bearing minerals. Also, to properly modify individual uncertainty estimates, a new PMF factor was identified, explaining a possible Pb contamination source.     

Allelochemical Effects of Volatile Compounds and Organic Extracts from <Emphasis Type="Italic">Muscodor yucatanensis,</Emphasis> a Tropical Endophytic Fungus from <Emphasis Type="Italic">Bursera simaruba</Emphasis>

Muscodor yucatanensis, an endophytic fungus, was isolated from the leaves of Bursera simaruba (Burseraceae) in a dry, semideciduous tropical forest in the Ecological Reserve El Eden, Quintana Roo, Mexico. We tested the mixture of volatile organic compounds (VOCs) produced by M. yucatanensis for allelochemical effects against other endophytic fungi, phytopathogenic fungi and fungoids, and plants. VOCs were lethal to Guignardia mangifera, Colletotrichum sp., Phomopsis sp., Alternaria solani, Rhizoctonia sp., Phytophthora capsici, and P. parasitica, but had no effect on Fusarium oxysporum, Xylaria sp., the endophytic isolate 120, or M. yucatanensis. VOCs inhibited root elongation in amaranth, tomato, and barnyard grass, particularly those produced during the first 15 days of fungal growth. VOCs were identified by gas chromatography/mass spectrometry and included compounds not previously reported from other Muscodor species and the previously reported compounds octane, 2-methyl butyl acetate, 2-pentyl furan, caryophyllene, and aromadendrene. We also evaluated organic extracts from the culture medium and mycelium of M. yucatanensis on the same endophytes, phytopathogens, and plants. In general, extracts inhibited plants more than endophytic or phytopathogens fungi. G. mangifera was the only organism that was significantly stimulated by both extracts regardless of concentration. Compounds in both organic extracts were identified by gas chromatography/mass spectrometry. We discuss the possible allelopathic role that metabolites of M. yucatanensis play in its ecological interactions with its host plant and other organisms.     

Characterization of Rice Husk Ash and Its Recycling as Quartz Substitute for the Production of Ceramic Glazes

In this work a complete characterization of rice husk ash (RHA) was conducted in order to evaluate mainly the composition and the thermal reactivity in terms of crystalline phase evolution. Moreover, the screening results of the research conducted on the possibility to use RHA as silica precursor in ceramic materials, such as ceramic glazes, were reported. The selected frits were prepared in a semiindustrial furnace and the obtained glasses were investigated in comparison with the frits prepared from pure quartz. Besides, laboratory glazes were obtained and characterized following the technical rules. This work allows to confirm the possibility to use RHA as silica precursor for the development of glazes for ceramic tile. The results evidenced, however, that it is not possible for a generalized production substitution of quartz with RHA.