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► Arachidic acid and zinc tetra-tert-butylphthalocyanine form mixed films with phase separation. ► The components are immiscible. ► The domains are in the sub-micro scale, detected ...with nanometric techniques, as AFM. ► Arachidic acid promotes the formation of a good monolayer with the phthalocyanine.
Mixed Langmuir and Langmuir-Blodgett films of dissimilar components, arachidic acid and a phthalocyanine of zinc, have been investigated. These compounds form mixed films with phase separation, with domains at the sub-micro scale which are detected by AFM in LB films but not observed by BAM. These domains present different contrast in the surface potential images obtained with SP-AFM and in the friction images. The analysis of the isotherms and of the AFM images, at several compositions, reveals that the components are immiscible. The difference in height between the arachidic acid and the phthalocyanine of zinc phases is in accordance with the heights of the molecules, and points to the presence of a monolayer in the zinc phthalocyanine phase. AFM has revealed as a necessary technique to elucidate the miscibility in mixed films at the nanometric scale. UV–Vis spectroscopy shows changes in the spectra bands of LB films in respect to those in solution, due to the organization of the molecules in the LB film.
Soil magnetism is greatly influenced by maghemite (γ-Fe
2O
3), the presence of which is usually attributed to the following: (1) heating of goethite in the presence of organic matter; (2) oxidation ...of magnetite (Fe
3O
4); or (3) dehydroxylation of lepidocrocite (γ-FeOOH). Formation of the latter two minerals in turn requires the presence of Fe(II) in the system. No laboratory experiment or soil study to date has shown whether maghemite can form from ferrihydrite, a poorly crystalline Fe(III) oxide ∼Fe
4.5(O,OH,H
2O)
13.5, below 250°C. However, ferrihydrite is the usual precursor of goethite (α-FeOOH) and hematite (α-Fe
2O
3), the most frequently occurring crystalline Fe(III) oxides in soils. Here is presented in vitro evidence that ferryhidrite can partly transform into maghemite at 150°C. This transformation occurs upon aging of ferrihydrite precipitated in the presence of phosphate or other ligands capable of ligand exchange with Fe-OH surface groups. This maghemite coexists with hematite and is a transient phase in the transformation of ferrihydrite to hematite, which is apparently stabilized by the adsorbed ligands. Its particle size is small (10 to 30 nm), and its X-ray diffraction pattern exhibits superstructure reflections. The possible formation of maghemite in Mars and in different Earth soils can partly be explained in the light of this pathway with minimal ad hoc assumptions.
The objective of the present study was to investigate the effects of a mixture of functional oils (Essential, Oligo Basics Agroind. Ltda) on performance response of chickens challenged with ...coccidiosis and the determination of apparent metabolizable energy (AME), nitrogen-corrected apparent metabolizable energy (AMEn), the coefficients of protein and ether extract digestibility and intestinal morphology of broilers fed with diets containing Essential. In Exp. 1, a completely randomized design (CRD) was used, with one control diet without Essential inclusion with coccidiosis (Eimeria acervulina, Eimeria maxima, and Eimeria tenella) challenged birds and two different inclusion rates of Essential (1.5 kg/ton and 2 kg/ton) with coccidiosis-challenged and non-challenged birds for each inclusion rate, using 10 replicates and 50 birds per experimental unit. After 7 d of coccidiosis challenge, the livability was approximately 10% lower (p<0.05) for the control group. Intestinal lesion scores were lower (p<0.05) in the anterior intestine and the cecum for the chickens supplemented. Feed efficiency and growth rate were improved in birds supplemented with Essential (p<0.05) before the coccidiosis challenge and during the first 7 d post infection. In Exp. 2, a CRD was used, with one control diet without Essential inclusion and one diet with inclusion of Essential (1.5 kg/ton), using nine replications and 33 chicks per pen. The diets with Essential yielded approximately 4% higher AME (p = 0.003) and AMEn (p = 0.001). Essential supplementation increased villus height in the jejunum on d 14 (p<0.05). Villus height:crypt depth ratio for the supplemented birds was larger (p<0.05) in the jejunum on d 7, larger (p<0.05) in the jejunum and ileum on d 14. In conclusion, these functional oils improved the energy utilization and the livability and decreased lesions caused by coccidiosis in supplemented birds.
Pedogenesis under aerobic conditions is usually associated with an increase in magnetic susceptibility (χ, mass-specific), which results from the formation of nano-sized magnetite and/or maghaemite. ...In this study, we systematically investigated the χ trend in Xeralfs from a chronosequence of 13 river terraces in an area with a Mediterranean climate in Spain. The soils in the younger terraces are well drained and reddened, but those of the older terraces exhibit redoximorphic features and reduced χ values, because of the presence of a perched water table. In the well-drained members of the chronosequence, the frequency dependent magnetic susceptibility, χFD, which is a proxy for the concentration of nano-sized pedogenic ferrimagnets such as maghaemite, was highly correlated with the concentration of haematite (Hm), but not with that of goethite (Gt). Also, the peak χFD increased with increasing age in the younger freely drained soils, indicating that no steady state had been reached, and decreased with increasing depth. The formation of maghaemite can be explained by either or both of two formation models, namely: (i) ferrihydrite rightward arrow maghaemite rightward arrow haematite solid state transformations; and (ii) the reaction of bacterially produced Fe(II) with an Fe hydroxide phase to form magnetite, which is later oxidized to maghaemite. Comparison between these soils and those in other climatic regions indicates that the Hm/χFD ratio increases with increasing soil temperature and with the degree of weathering. In the horizons exhibiting redoximorphic features on the higher terraces, there was significantly less Hm and χFD in clay than in the well-drained younger soils, possibly because of reductive dissolution of haematite and maghaemite. Laboratory experiments showed that susceptibility to reductive dissolution increased in the sequence goethite < maghaemite < haematite, which is consistent with the relative abundance of these minerals in the redoximorphic horizons.
We present the design, data and results from the NEXT prototype for Double Beta and Dark Matter (NEXT-DBDM) detector, a high-pressure gaseous natural xenon electroluminescent time projection chamber ...(TPC) that was built at the Lawrence Berkeley National Laboratory. It is a prototype of the planned NEXT-100 136Xe neutrino-less double beta decay (0νββ) experiment with the main objectives of demonstrating near-intrinsic energy resolution at energies up to 662 keV and of optimizing the NEXT-100 detector design and operating parameters. Energy resolutions of ∼1% FWHM for 662 keV gamma rays were obtained at 10 and 15 atm and ∼5% FWHM for 30 keV fluorescence xenon X-rays. These results demonstrate that 0.5% FWHM resolutions for the 2459 keV hypothetical neutrino-less double beta decay peak are realizable. This energy resolution is a factor 7-20 better than that of the current leading 0νββ experiments using liquid xenon and thus represents a significant advancement. We present also first results from a track imaging system consisting of 64 silicon photo-multipliers recently installed in NEXT-DBDM that, along with the excellent energy resolution, demonstrates the key functionalities required for the NEXT-100 0νββ search
•Films of a zinc tetra-tert-butylphthalocyanine were obtained from several techniques.•Films from immersion and Langmuir-Blodgett are uniform and electrochemically similar.•Drop cast films show the ...influence of adsorbed molecular oxygen.•An increase of the film oxidation intensity is obtained after oxygen exposition.
Organized thin films of a zinc phthalocyanine have been deposited on solid electrodes using several techniques, such as drop casting, immersion and Langmuir-Blodgett (LB), at several conditions, and their electrochemical response has been studied by cyclic voltammetry and differential pulse voltammetry. Topographical images by Atomic Force Microscopy reveal that the structure of immersion and LB films is uniform, showing granular aggregates and continuous layers, respectively. The electrochemical response of both kind of films is similar and shows peaks that can be correlated with redox processes occurring in the phthalocyanine ring. Drop casting films present a different topography, with rod-like structures, and the voltammograms show an enhancement in the peaks at positive potentials, which has been attributed to the influence of the atmospheric oxygen adsorbed during the film deposition. Immersion and LB films have also shown an increase in the oxidation current intensity of the voltammetric response after exposition to molecular oxygen. These results point to a possible application of these organized t-BuZnPc thin films as electrochemical oxygen sensors.
Soil formation under aerobic conditions usually enhances magnetic signals, mainly through neoformation of sub-micron magnetite and/or maghemite. In order to better understand the nature and magnitude ...of the enhancement, in this work we characterized the iron (Fe) oxides and magnetic properties of two Calcic Luvisols (Chromic) developed on calcareous orthoquartzites in a Spanish region with a warm Mediterranean climate. Weathering of the Fe-bearing minerals in the parent material (mostly Fe-rich smectite) had resulted in the neoformation of hematite and maghemite rather than goethite, thus causing a substantial increase in magnetic susceptibility,
χ, saturation magnetization,
M
s, and other magnetic signals. The absolute frequency-dependent magnetic susceptibility,
χ
FD, which is a typical proxy for the concentration of sub-micron superparamagnetic pedogenic maghemite, was strongly correlated with the concentration of hematite (Hm). The estimated percent frequency-dependent magnetic susceptibility,
χ
FD%, was 15.7%. This and various other magnetic indicators indicate that the grain size distribution (GSD) of the pedogenic maghemite is narrower around the superparamagnetic/single domain threshold than is that of maghemite in soils and paleosols developed under other temperate climates (e.g., the Chinese Loesss Plateau, where
χ
FD%
<
13%). Our results are consistent with predictions based on the ferrihydrite
→
maghemite
→
hematite transformation model. Also, they suggest that a wise combination of the Hm/
χ
FD ratio,
χ
FD%, the hematite/goethite ratio, and several indicators of the degree of weathering provides a better tool for paleoclimatic reconstructions than does the current use of
χ alone.
In this work we report the fabrication of Langmuir and Langmuir–Blodgett (LB) films of a substituted ZnPc (octakis(oxyoctyl)phthalocyanine of zinc), and their characterization by means of several ...techniques. These characterization techniques include surface pressure (π-A) and surface potential (ΔV-A) isotherms as well as UV–vis Reflection spectroscopy and Brewster Angle Microscopy (BAM) for the films at the air–water interface together with UV–vis absorption and IR spectroscopies and Atomic Force Microscopy (AFM) for the LB films. The π-A and ΔV-A isotherms and BAM images indicate a phase transition at a surface pressure of ca. 9mN/m and a multilayer formation at surface pressures around 19–20mN/m; at a surface pressure around 27mN/m a disordered collapse of the film occurs. In addition, AFM images of LB films at π=10mN/m and π=20mN/m show a monomolecular and a multilayered film, respectively. The comparison of the UV–vis spectrum of ZnPc in solution, the reflection spectra of the Langmuir films and UV–vis spectra of LB films reveals a significant reduction in the Q band intensity for the films, indicative of an organization of ZnPc in the Langmuir and LB films versus the random distribution in solution. The UV–vis Reflection spectra are also consistent with multilayer formation at surface pressures around 19–20mN/m. The relative intensities of the IR spectrum bands change from the KBr pellet to the LB film which is also attributable to orientation effects in the film. Cyclic voltammetric experiments of LB films incorporating the ZnPc derivative show peaks that can be correlated with redox processes occurring in the phthalocyanine ring. A small but significant influence of the surface pressure and the number of deposited layers in the electrochemical behaviour is observed. The electrochemical response of cast films exhibits some differences with respect to that of LB films which have been attributed to their different molecular organizations.
•A zinc substituted phthalocyanine has been assembled by means of the LB technique.•LB films show a higher degree of order than cast films.•Surface pressure and number of layers influence the electrochemical behaviour.•The gap between the HOMO and LUMO levels has been determined from electrochemistry.
The proportion of water stable aggregates larger than 0.25
mm (WSA), mean weighted aggregate diameter (MWD) and water dispersible clay (WDC) are three good indicators of the risk of surface sealing, ...runoff generation and soil erosion by water. These aggregation indices are influenced by the contents in clay, iron oxides, calcium carbonate and organic matter, among other soil properties. Because these soil components possess specific spectral characteristics, one can use reflectance measurements to estimate the previous aggregation indices. To this end, we sampled the surface layer of 80 soils developed on granodiorites, quartzites, sandstones, shales and marls in southwestern Spain. Diffuse reflectance spectra were recorded with an Ultraviolet–Visible–Near Infrared (UV–Vis–NIR) spectrophotometer equipped with a diffuse reflectance sphere for the 300–2500
nm range, a Vis–NIR spectrophotometer with a spinning sample module for the 400–2500
nm range, and a mid infrared (MIR) spectrophotometer with a diffuse reflectance hemisphere accessory for the 4000–500
cm
−
1
(2500–20,000
nm) range. Partial least-squares regression analysis based on log (1
/
Reflectance) for various spectral ranges provided good estimates of the concentrations of calcium carbonate (
R
2
=
0.95; standard error of validation (SEV)
=
56
g
kg
−
1
), clay (
R
2
=
0.84; SEV
=
54
g
kg
−
1
), free iron oxides (
R
2
=
0.83; SEV
=
3.3
g
kg
−
1
), and acceptable estimates for pH (
R
2
=
0.69; SEV
=
0.6), organic matter (
R
2
=
0.41; SEV
=
5.2
g
kg
−
1
), WSA (
R
2
=
0.60; SEV
=
67
g
kg
−
1
), MWD (
R
2
=
0.62; SEV
=
0.4
mm), and WDC (
R
2
=
0.66; SEV
=
29
g
kg
−
1
). The instrument/wavelength range combination providing the highest
R
2 values and accuracy (lowest SEV) was found to depend on the particular soil property. The goodness of prediction from measurements of the fine (<
2
mm) earth and ground (<
0.1
mm) samples was similar. Overall, our results suggest that diffuse reflectance spectroscopy is useful for (i) categorising soil zones according to aggregate stability (and hence susceptibility to water erosion); and (ii) as a screening tool for deciding whether any further laboratory analyses are needed, among other purposes.
There is a growing demand for detailed information on soil properties. This information can be used as a guideline for sustainable production. The objective of this work was to assess the use of ...magnetic susceptibility (MS) and diffuse reflectance spectroscopy (DRS) for characterizing the spatial variability of soil physical and chemical properties, as well as sites with different potentials for sugarcane production, in an Haplustalf of southeastern Brazil. To this end, topsoil (0–0.20m) and sugarcane samples were collected at the nodes of a 10m square grid spanning an area of 1ha. We compared the correlation between MS and DRS with the canonical pair (r=−0.26 to −0.34; P<0.01) and we also compared the spatial variability models. Based on the relation between the original variables and the first canonical pair, 20% of the variance in plant properties was explained by soil attributes that did not include MS and DRS. The range values of MS (33m) and DRS (29 to54m) were next to those adjusted for the canonical variables of the attributes of soil (30m) and plant (34m). Thus, the results of this study may serve (i) to guide future work on detailed mapping in similar areas that may incorporate MS and DRS as predictive variables, and (ii) to establish the best strategy of combination of geostatistics and canonical correlation analysis for the identification of areas with different sugarcane production potential.
•Geostatistics and multivariate analysis are recommended for recognition of sugarcane production.•Detailed mapping allows capturing the relation of cause–effect between soil and crops.•Magnetic susceptibility and diffuse reflectance spectroscopy can be used in mapping.
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