Inversion method for obtaining electrical parameters for soil in the rural region in Brazil

This paper presents an inversion methodology through weighted least squares to obtain the electrical parameters for the soil of a typical mid-western region in Brazil using the model based in the formalism of the parabolic equations to calculate the electric field intensity received. To validate this methodology, the results of the radio signal measurement campaign conducted in six radial routes leaving the city of Brasilia, Federal District, where the transmitter was located, were used. The measurements were compared to computer simulations and, thus, the optimal values for the electric conductivity and relative permittivity for the soil of the region could be estimated. Finally, a quantitative analysis of these parameters was performed with the values found in the literature, which demonstrated the effectiveness of the proposed methodology.

Funções de Wannier generalizadas para aplicações em Ciência dos Materiais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Chemical composition and metabolizable energy values of corn germ meal obtained by wet milling for layers

An experiment was carried out to determine the chemical composition, metabolizable energy values, and coefficients of nutrient digestibility of corn germ meal for layers. The chemical composition of corn germ meal was determined, and then a metabolism assay was performed to determine its apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen (AMEn) values and its dry matter and gross energy apparent metabolizability coefficients (CAMDM and CAMGE, respectively). In the 8-day assay (four days of adaptation and four days of total excreta collection), 60 29-week-old white Lohman LSL layers were used. A completely randomized experimental design, with three treatments with five replicates of four birds each, was applied. Treatments consisted of a reference diet and two test diets, containing 20 or 30% corn germ meal. Results were submitted to analysis of variance and means were compared by the Tukey tests at 5% probability level. The chemical composition of corn germ meal was: 96.39% dry matter, 49.48% ether extract, 1.87% ashes, 7243 kcal gross energy/kg, 11.48% protein, 0.19% methionine, 0.21% cystine, 0.48% lysine, 0.40% threonine, 0.72% arginine, 0.35% isoleucine, 0.83% leucine, 0.57% valine, and 0.37% histidine, on as-fed basis. There were no statistical differences in AME, AMEn, CAMDM, and CAMGE values with the inclusion of 20 and 30% corn germ meal in the diets. On dry matter basis, AME, AMEn, CAMDM, and CAMGE values of corn germ meal were: 4,578 and 4,548 kcal/kg, 4,723 and 4,372 kcal/kg, 64.95 and 61.86%, respectively.

Dietary fiber inclusion as an alternative to Feed Fasting to induce molting in Commercial Layers

The objective of the present experiment was to compare the performance, egg quality and organ morphometrics of commercial layers submitted to alternative forced molting methods using dietary fibers. The experimental period included the phases of molting, rest, and second laying cycle (six periods of 28 days each). In the trial, 320 commercial Isa Brown layers with 72 weeks of age were distributed, according to a completely randomized experimental design into five treatments with eight replicates of eight birds each, totaling 40 experimental units. Molting was induced by feeding diets with the inclusion of alfalfa or soybean husks at 80% and 60% or feed fasting. Treatments were applied for 14 days. Performance and egg quality parameters were evaluated for the second laying cycle and organ morphometrics (liver, gizzard, proventriculus, reproductive apparatus) in two different slaughter dates. The obtained data were submitted to analysis of variance using the General Linear Model (GLM) procedure of SAS statistical package (SAS Institute, 2002). Alternative molting methods promoted similar performance and egg quality results after molting were similar to those obtained by the conventional fasting method. Feeding fiber produced the expected effects in terms of organ weight regression and recovery and may be used to induce molting in commercial layers.

High-fiber diets with reduced crude protein for commercial layers

This study aimed at evaluating diets containing different fiber sources and two crude protein levels on the performance, egg quality, and nitrogen metabolism of commercial layers. In total, 392 48-wk-old Isa Brown layers were distributed according to a completely randomized experimental design in a 3x2+1 (control) factorial arrangement, resulting in seven treatments with seven replicates of eight birds each. Treatments consisted of three fiber feedstuffs (cottonseed hulls, soybean hulls, and rice hulls) and two dietary crude protein levels (12% and 16%). Cottonseed hulls associated with the high crude protein level (16%) resulted in the worst feed conversion ratio per dozen eggs. Diets with 16% crude protein resulted in the highest feed intake, egg production, egg weight, egg mass values, and improved feed conversion ratio (kg eggs/kg feed). The dietary inclusion of soybean hulls determined low yolk pigmentation, and of rice hulls, low egg specific gravity. The 16% crude protein diet with rice hulls promoted the best feed conversion ratio. Hens fed the reference diet presented higher egg mass and better feed conversion ratio per kg eggs and per dozen eggs. Hens fed the diets with low crude protein level (12%) had reduced nitrogen excretion, but presented worse egg production.

Measuring Quantum Capacitance in Energetically Addressable Molecular Layers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hard X-ray photoemission study of the Fabre salts (TMTTF)(2)X (X = SbF6 and PF6)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Magnetic-size effects in ultrathin layers

We study N-layer samples (N ≤ 10) for the Heisenberg model, with ferro- and antiferromagnetic exchange couplings, using a modified version of the Onsager reaction field approximation. The present scheme includes short-range spin-spin correlations, and allows for layer-dependent order parameters when free surface boundary conditions are imposed. The limits N = 1 (two dimensions) and N → ∞ (three dimensions) can be solved analytically, while systems with several layers have to be numerically calculated. We found no indication of a phase transition at finite temperature up to the sizes investigated (N = 10), the layered systems behaving essentially as two-dimensional. A phase transition is only obtained for the three-dimensional limit. © 1993.

Influence of polyaniline and phthalocyanine hole-transport layers on the electrical performance of light-emitting diodes using MEH-PPV as emissive material

The influence of layer-by-layer films of polyaniline and Ni-tetrasulfonated phthalocyanine (PANI/Ni-TS-Pc) on the electrical performance of polymeric light-emitting diodes (PLED) made from (poly[2-methoxy-5-(2`-ethyl-hexyloxy)-1,4-phenylene vinylene]) (MEH-PPV) is investigated by using current versus voltage measurements and impedance spectroscopy. The PLED is composed by a thin layer of MEH-PPV sandwiched between indium tin oxide (ITO) and aluminum electrodes, resulting in the device structure ITO/(PANI/Ni-TS-Pc)(n)/MEH-PPV/Al, where n stands for the number of PANI/Ni-TS-Pc bilayers. The deposition of PANI/Ni-TS-Pc leads to a decrease in the driving voltage of the PLEDs, which reaches a minimum when n = 5 bilayers. In addition, impedance spectroscopy data reveal that the PLED impedance decreases as more PANI/Ni-TS-Pc bilayers are deposited. The PLED structure is further described by an equivalent circuit composed by two R-C combinations, one for the bulk and other for the interface components, in series with a resistance originated in the ITO contact. From the impedance curves, the values for each circuit element is determined and it is found that both, bulk and interface resistances are decreased upon PANI/Ni-TS-Pc deposition. The results indicate that PANI/NiTS-Pc films reduce the contact resistance at ITO/MEH-PPV interface, and for that reason improve the hole-injection within the PLED structure. (c) 2007 Elsevier B.V. All rights reserved.

Organic light emitting diodes with europium (III) emissive layers based on beta-diketonate complexes: The influence of the central ligand

This work shows a comparative study of organic light emitting diodes based on four different europium complexes with the general formula, Eu(CLs)(3)bipyridine, where the central ligands are DBM [tris(dibenzoylmethane)], TTA [tris(1-(2-thieneyl)-4,4,4-trifluoro-1,3-butanedione)], NTA [tris(1-(2-naphthoyl)-3,3,3-trifluoroacetone)] and BTA [tris(1-(2-benzoyl)-3,3,3-trifluoroacetone)]. All devices have a driving voltage of 14-16 V, a very low electrical current at normal operation (less than 1 mA) and a good Wall Plug Efficiency (up to near 10(-3)%). The most suitable central ligand was found to be DBM, with an optical power up to 200 nW (at 612 nm). The BTA exhibits the lowest stability under high applied voltages. The other central ligands have similar results among them. The electroluminescence spectra clearly show the europium ion transitions (with a strong (5)D(0) -> (7)F(2) line) with a CIE color coordinate around (0.56, 0.34). (C) 2008 Elsevier B.V. All rights reserved.

Metabolizable energy and oil intake in brown commercial layers

With the objective to establish the best metabolizable energy (ME) intake for layers, and the best dietary vegetable oil addition level to optimize egg production, an experiment was carried out with 432 30-week-old Hisex Brown layers. Birds were distributed into nine treatments with six replicates of eight birds each according to a 3 x 3 factorial arrangement, consisting of three daily metabolizable energy intake (280, 300 or 320 kcal/bird/day) and three oil levels (0.00; 0.75 and 1.50 g/bird/day). Daily feed intake was limited to 115, 110 and 105 g/bird in order to obtain the desired energy and oil intake in each treatment. The following parameters were evaluated: initial weight, final weight, body weight change, egg production, egg mass, feed conversion ratio per dozen eggs and per egg mass and energy conversion. There was no influence of the treatments on egg production (%) or egg mass (g/bird/day). Final weight and body weight change were significantly affected by increasing energy intake. Feed conversion ratio per egg mass, feed conversion ratio per dozen eggs and energy conversion significantly worsened as a function of the increase in daily energy intake. An energy intake of 280 kcal/bird/day with no addition of dietary oil does not affect layer performance.

The Use of Nanotechnology in Cosmetic Formulations: The Influence of Vehicle in the Vitamin A Skin Penetration

Despite the efficacy of topical retinoic acid, skin reactions have limited its acceptance by patients. Other retinoids, like Retinyl Palmitate (RP), are considerably less irritating, but they are also less effective. In order to enhance the performance of retinoids, in this work RP has been added to cosmetic formulations such as nanoemulsions, which can provide better penetration of this active substance. Because the vehicle can directly influence the skin penetration and the effectiveness of RP, two skin care products containing 5000 UI RP have been developed and investigated, namely a nanoemulsifying system and a classic gel cream. In vitro penetration tests were conducted by using Franz diffusion cells and placing porcine ear skin and iso-propanol in the receptor compartment. The RP concentration in the skin layers was analyzed by high performance liquid chromatography, and a Zeta-Sizer system was employed for measurement of the the particle size distribution. The penetration tests revealed a large difference between the vehicles in terms of the RP concentrations in each skin layer. The classic gel cream furnished better RP penetration in both the stratum corneum and the epidermis without stratum corneum + dermis, as compared to the self-nanoemulsifying system. The two vehicles displayed the same particle size (between 100 and 200 nm). Better understanding of RP skin delivery using different vehicles has been acquired, and the importance of evaluating the efficacy of nanocosmetics. Results from the present study should also contribute to the assessment of commercial self-nanoemulsifying systems with potential application in the facile production of nanoemulsions.

Arterial Spin Labeling Measurements of Cerebral Perfusion Territories in Experimental Ischemic Stroke

Collateral circulation, defined as the supplementary vascular network that maintains cerebral blood flow (CBF) when the main vessels fail, constitutes one important defense mechanism of the brain against ischemic stroke. In the present study, continuous arterial spin labeling (CASL) was used to quantify CBF and obtain perfusion territory maps of the major cerebral arteries in spontaneously hypertensive rats (SHRs) and their normotensive Wistar-Kyoto (WKY) controls. Results show that both WKY and SHR have complementary, yet significantly asymmetric perfusion territories. Right or left dominances were observed in territories of the anterior (ACA), middle and posterior cerebral arteries, and the thalamic artery. Magnetic resonance angiography showed that some of the asymmetries were correlated with variations of the ACA. The leptomeningeal circulation perfusing the outer layers of the cortex was observed as well. Significant and permanent changes in perfusion territories were obtained after temporary occlusion of the right middle cerebral artery in both SHR and WKY, regardless of their particular dominance. However, animals with right dominance presented a larger volume change of the left perfusion territory (23 +/- 9%) than animals with left dominance (7 +/- 5%, P<0.002). The data suggest that animals with contralesional dominance primarily safeguard local CBF values with small changes in contralesional perfusion territory, while animals with ipsilesional dominance show a reversal of dominance and a substantial increase in contralesional perfusion territory. These findings show the usefulness of CASL to probe the collateral circulation.