Lead-cadmium oxyfluoride glasses and glass-ceramics

Glasses and glass-ceramics have been obtained in oxyfluoride systems involving lead and cadmium fluorides and one of the well-known glass former oxides SiO2, B2O3 and TeO2. Vitreous domains were established and a wide range of compositions including high heavy metal contents lead to stable glasses. Amorphous structures have been studied by short-range order spectroscopy techniques (Raman scattering and x-ray absorption) and molecular basic structures have been identified. Besides the usual oxides, the role of glass former could also be proposed for cadmium ions. Special attention has been paid for crystallization process. Cubic lead fluoride, cubic lead tellurite, tetragonal tellurium oxide and a solid solution of the type Pb1-xCdxF2 are obtained as crystallization products depending on the composition and temperature of heat treatments. Pb1-xCdxF2 solid solutions are well known superionic materials and obtaining this solid solution as a crystal phase could be very interesting for applications concerning ionic electrical conduction properties. The addition of rare earth ions led to the control of the crystallization process. In the presence of the nucleating ion only the cubic form beta-PbF2 was identified. Rare earth ions are present in the crystal phase and crystal-like spectroscopic properties were observed suggesting interesting applications for these perfectly transparent glass ceramics in photonics.

Spectroscopic properties of lead fluoroborate glasses doped with ytterbium

A new lead fluoroborate glass (PbO-PbF2-B2O3) doped with ytterbium (Yb:PbFB) is presented. Samples with different concentrations of Yb3+ were produced and had their emission cross-sections, fluorescence lifetimes and minimum pump intensities determined. They have high refractive index of 2.2 and a density of 4.4 g/cm(3). For a doping level of 1.153x10(20) ions/cm(3), the fluorescence lifetime, after excitation at 968 nm, is 0.81 ms, which is comparable to Yb:tellurite laser glass. Also, an emission band at 1022 nm is measured with emission cross-section of approximately 1.07x10(-20) cm(2) and fluorescence effective linewidth of 60 nm, which is comparable to Yb:phosphate laser glass. (C) 2001 Optical Society of America.

Study of the most suitable new glass laser to incorporate ytterbium: alkali niobium tellurite, lead fluorborate or heavy metal oxide

Diode-pumped Yb-doped glass lasers have received considerable attention for applications such as high-power beam production or femtosecond pulses generation. In this paper, we evaluate the laser potential of three different glass families doped with Yb3+ : alkali lead fluorborate (PbO-PbF2-B2O3), heavy metal oxide (Bi2O3-PbO-Ga2O3) and niobium tellurite (TeO2-Nb2O5-K2O-Li2O). Spectroscopic properties were studied for the samples and calculations of the minimum laser pump intensity (I-min), saturation fluence (U-sat) and the theoretical limit of peak power (P-max) are also presented. A comparison of laser properties of these three different glasses and their importance is shown and analyzed. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Root-system of peanuts as affected by phosphorus fertilization

There have been some responses of peanut roots to phosphorus. An experiment was carried out to study peanut root growth and distribution as related to P in the soil. The cultivars Tatu, Oira and Tup4 and the lines FCA 170 and FCA 265 were grown with or without P fertilization with 80 kg P2O5/ha, as triple superphosphate. The fertilizer was applied in the seed furrows. There was higher P contents in the 0-10 cm layer of the soil 36 days after P application. At 66 and 98 days after application, P contents of the soil were increased by fertilization down to 15 cm. There was no response of peanut roots to P fertilization. Oira showed the highest root lenght density and Tatu the lowert. There was a root concentration the first 15 cm of the soil. Oira with the largest root system showed the lowest P absorption, and Tatu, with the smallest root system absorbed as much P as the others.

Effect of boron powder purity on superconducting properties of MgB2

The effect of the properties of starting boron powders on the superconducting properties of MgB2 has been studied. The 92% and 96% pure powders produce lower surface reactivity and larger particle size than the 99% boron powder, as can be seen from Brunauer - Emmett - Teller (BET) and scanning electron microscopy (SEM) results, indicating that the low purity powders cannot be used to archive the same superconducting properties as those of samples made from pure 99% boron powder. However, the purity of 92% and 96% boron powders can be improved by using a simple chemical process, leading to enhanced magnetic critical current densities J(c). From x-ray diffraction (XRD) measurement, oxide impurity has been observed, which might be originated from the B2O3 phase in the boron powders. In order to get high performance MgB2, it is obviously important to control the phase composition and microstructure of amorphous boron starting powders and solid reaction conditions.

Evaluation of laser level populations of erbium-doped glasses

A simulation of erbium-doped glass systems, which provides population density for the excited states involved in the 1.5 mu m and also for 2.7 mu m emissions when pumped around 980 nm, is presented. To describe the diode pump laser processes, a theoretical model based in a coupled system of differential rate equations was developed. The approach used and the obtained spectroscopic parameters are discussed. The materials under study are two oxide glasses, lead fluoroborate (PbO-PbF2-B2O3), and heavy metal oxide (Bi2O3 PbO-Ga2O3) and a fluoride glass (ZrF4-BaF2-LaF3-AlF3-NaF), all of them doped with Er3+. (c) 2006 Elsevier B.V. All rights reserved.

Er3+-doped germanate glasses for active waveguides prepared by Ag+/K+ <-> Na+ ion-exchange

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Qualidade tecnológica da cana-de-açúcar sob adubação com torta de filtro enriquecida com fosfato solúvel

The study had the objective to evaluate the effect of the fertilization with filter cake enriched with soluble phosphate on the sugar yield. The experiment carried at Presidente Prudente-SP, used a randomized complete block design, in the factorial scheme 5 x 4, where the first factor consisted of doses of filter cake (0; 0.5; 1.0; 2.0 and 4.0 t ha(-1)) and the second, doses of phosphorus fertilizer (0, 50, 100, 200 kg ha(-1) of P2O5), with 4 replicates, totaling 80 plots. The results indicated that phosphorus applied in planting furrows improves the quality of sugarcane raw matter by increasing the levels of soluble solids, total reducing sugars and sucrose in the stalks. The phosphorus also increases the productivity of sugar. The filter cake applied in planting furrow has the potential to partially replace the chemical fertilization with phosphate aiming to improve the quality and the productivity of sugar. The best combination was filter cake at dose between 2.6 and 2.7 t ha(-1) combined with dose between 160 and 190 kg P2O5 ha(-1) for obtaining best response of soluble solids and productivity of sugar.

Evaluation of the components of production of the ricinus according of rates of calcareous rock and match

The soil of the Paraiba, in generality, are acid and with low levels of available match, seriously limiting the income of the plants. A research in vegetation house was lead, with the objective to evaluate doses of calcareous soil and match in the culture of ricinus. The treatments had been composites for five levels of match: 0.0; 80; 160; 240 and 360 kg ha(-1) of P(2)O(5) and four dosis of calcareous rock: 0.0; 2.5; 3.5 and 4.5 t ha(-1) in experimental delineation of blocks casualized with 4 factorial project x 3 (four levels of match and three doses of calcareous soil) more two treatments you add zero of match (0.0 P(2)O(5): 2,5 t ha(-1) of calcareous soil) and calcareous soil zero (240 P(2)O(5): 0.0 t ha(-1) of calcareous soil), with three repetitions. The calcareous soil reduced the acidity of the ground and effect of the application of the match (>= 80 kg ha(-1) of P(2)O(5)) in the presence of the collagen (>= 2.5 t ha(-1) of CaCO(3)) with of the calcareous soil (>= 2.5 t ha(-1) of CaCO(3)) in the presence of the match was not verified well (>= 80 kg ha(-1) of P(2)O(5)). The match applied in the absence of the calcareous soil was limited to the income of the culture of what the calcareous soil in the absence of the match.

Adubação organomineral e biofertilização líquida na produção de frutos de pinheira ( Annona squamosa L.) no submédio São Francisco, Brasil

The organic production systems based on natural processes do not allow the use of synthetic fertilizers with a high solubility, so it is required the use of technologies in accordance with the organic production legislation in order to make the technical, economical and environmental sustainable activities viable. To evaluate the effects of the usage of mineral and organic natural fertilizers, associated with liquid biofertilizers (BLE= enriched liquid biofertilizer and BF= leaf biofertilizers) on the production of the sugar apple fruit crop Annona squamosa L., replacing totally the chemical fertilizers, used by conventional farming systems, a nine year old orchard was driven in the irrigated plot n degrees 1295, irrigated project Nilo Coelho, district of Petrolina - PE. The experiment was carried out from September 2005 to February 2006. The experimental design was done through randomized blocks with eight treatments and four replications in plots of three plants each, with 96 plants in total. The treatments were the following: T(1) - plants with no fertilizer; T(2) - 60 g de N + 32 g de P(2)O(5) + 48 g de K(2)O; T(3) - 90g de N + 32 g de P(2)O(5) + 48 g de K(2)O; T(4) - 30 g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 15 L de BLE + BF a 5 %; T(5) - 60g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 30 L de BLE + BF a 5 %; T(6)- 90g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 45 L de BLE + BF a 5 %; T(7) - 120g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 60 L de BLE + BF a 5 %; T(8) - 150 g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 75 L de BLE + BF a 5 % The fruit growth analyses (diameter and average length), total yield, productivity, average fruit weight, average number of fruits, fresh weight of the skin and pulp and dry weight of the fruits were used to evaluate the experiment. The results were relevant to the total production, fresh weight of the skin and dry weight of the fruits. The use of organominerals associated with liquid fertilizers increased significantly the productivity in values ranging from 10.44% (T(5) = 1.98 t ha(-1)) to 24.52 % (T(7) = 12.34 %). The treatment T(3) stood out (90g de N + 32g de P(2)O(5) + 48g de K(2)O) with a higher production than the control. The fruit weight increased in the fertilized treatments, with values increasing from treatment (T(2) = 5.26 %) to the treatment (T(7) = 12.34 %) in relation to the control. The fruit development was characterized by an average growth increase of 82 % in length and 84 % in diameter until the 56(th) day, with a sigmoidal growth pattern.

Enhanced luminescence of Tb3+/Eu3+ doped tellurium oxide glass containing silver nanostructures

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Adubação fosfatada, produção e qualidade de sementes de populações de amendoim

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Geochemical Variability of the Rapakivi Itu Province, State of São Paulo, SE Brazil

This paper describes the chemical variability of the Late Precambrian Itu Rapakivi Province (IRP), State of São Paulo, SE Brazil, based on 187 selected analyses from the Itu, São Francisco, Sorocaba, Campina do Veado and Sguario/ Correa granites. The IRP has an almost uniform petrographic character conferred by the overall dominance of subalkaline biotite granites. Monzogranites (adamellites), granodiorites, quartz syenites, quartz monzonites are rare to very rare rock types and tonalites and quartz diorites are almost restricted to enclaves. Typical chemical features are the high FeO*/MgO ratio, a clustering of the K2O values between 4.5 and 6.0 wt.% and K2O/Na2O ratios which define the IRP as mildly potassic although more potassic rocks also occur. The overal Peacock Alkalinity Index is 54 defining the Province as alkali-calcic. In the Shand diagram the data cluster near the metaluminous/peraluminous boundary. Relationships between Nb, Rb and Y stress the within plate character of the IRP and the relationships between Rb, Ba and Sr reveal the importance of feldspar fractionation in magma evolution. The data also show an interbody and an intrabody chemical variability due to the variation in the composition of the crustal magma protoliths, as assigned by K/Rb relations. The presence of several magmatic cycles which built up the major intrusions reflects a magma ascent from collecting chambers successively drained and recharged, a feature in agreement with the clear link between the bodies and long lived, successively reactivated, transcurrent faults. Most of the chemical features of the IRP correspond to those of the classical Finnish rapakivi granites.

Magneto-optical rotation of heavy-metal oxide glasses

Magneto-optical rotation was measured at room temperature for glasses containing Bi2O3-CdO-GeO2 (BCG), and Bi2O3-PbO-GeO2-B2O3 (BPGP). A pulsed magnetic field between 50 and 80 KG was used to measure Faraday rotation at 632.8 nm as a function of the concentration of Bi and Cd for BCG and Bi and Pb for BPGB. Verdet constant as high as 0.162 min G-1 cm-1 at 632.8 nm for the BPGB sample with the highest concentrations of Bi and Cd was found. Verdet constant increases linearly with the heavy-metal concentration for the BPGB whereas it reaches some saturation for the BCG system. Measurements of the magneto-optical rotation at other wavelengths in the visible and the refractive index at 632.8 nm are also reported. © 1998 Elsevier Science B.V. All rights reserved.

Aditivos na ensilagem do capim-elefante. I. Composição bromatológica das forragens e das respectivas silagens

The effect of the addition of ground ear corn with husks, wheat bran and saccharin, on the rate of 0, 8, 16 and 24% (dry weight of additive/wet weight of cut green grass), upon the chemical composition of both fodder and silage of Pennisetum purpureum Schum. cv. Guaçu was evaluated. A split-plot randomized block design was used. The plots were the additives and their levels and the sub-plots the material types (forage + additives and their silages). The grass was fertilized with 20 t/ha of green manure and 80, 160 and 160 kg/ha of P2O5, N and K2O, respectively. The material (chopped grass mixed with the levels of the additives) was ensiled in experimental silos (200 L plastic vessels). The dry matter percentages increased linearly as additive levels increased, being greater the effect of ground ear corn with husks. Wheat bran addition and saccharin increased the crude protein and soluble carbohydrates percentages while the ground ear corn with husks addition decreased them. Losses of dry matter soluble compounds (CP, ash and NFE) and a relative rise in the less soluble compounds (CF and organic matter) were observed.