Highly oriented films of Sr2FeMoO6 were fabricated by ultrasonic spray pyrolysis. A combined organic/inorganic solution was developed and the films were deposited on single-crystal LaAlO3 between 600 °C and 900 °C followed by postannealing at 850 °C or 1200 °C in Ar/5% H2. Optimum films showed a metallic resistivity behavior with less than a 0.25% magnetoresistive effect at 50 K, 1 T, indicative of highly quality intra- and intergranular material. At 4.2 K, the lower bound saturation magnetization, Ms was ∼2.5 μB/f.u. and the transport spin polarization was 60±3%.

Neste trabalho foi preparado um eletrodo altamente seletivo de membrana de PVC com o complexo cobalto-salofen. O sensor mostra uma seqüência seletiva anti-Hofmeister, com preferência por íons iodeto sobre vários anions comuns. O eletrodo apresentou uma dinâmica linear na faixa de 5,0×10-7 a 1,0×10 -1 mol L -1 , com uma inclinação Nernstiana de -58,9 mV com um limite de detecção de 3,0×10-7 mol L -1 . A região de pH de trabalho do sensor é de 3,1 a 9,8. A leitura rápida é de 15 s, e tem uma vida útil de 2 meses. Os coeficientes de seletividade para o eletrodo proposto foram melhorados para alguns interferentes, se comparado com os eletrodos de membrana de iodeto disponíveis. O eletrodo proposto foi aplicado com sucesso na determinação direta de iodeto em sal comestível e como eletrodo indicador na titulação potenciométrica de I -contra Ag + .A highly selective PVC membrane electrode based on a cobalt-salophen complex was prepared. The sensor displays an anti-Hofmeister selectivity sequence with a preference for iodide ion over many common anions. The electrode has a linear dynamic range between 5.0×10 -7 to 1.0×10 -1 mol L -1 , with a Nernstian slope of -58.9 mV decade -1 and a detection limit of 3.0×10 -7 mol L -1 . The working pH range of the sensor is 3.1-9.8. It exhibits of a fast as 15 s and has a lifetime of about 2 months. The selectivity coefficients for the proposed electrode were improved for some interferences, when compared with those of available iodide membrane electrode. The proposed electrode was successfully applied for the direct determination of iodide in edible salt and as an indicator electrode in potentiometric titration of I -against Ag + .

Simultaneous kinetic-spectrophotometric determination of a ternary mixture of hydrazine (HZ) and its derivatives by principal component regression (PCR) and partial least squares (PLS) calibration is described. The methods were based on the difference observed in the reduction rate of iron(III) with HZ, thiosemicarbazide (TSCZ) and phenylhydrazine (PHZ) in the presence of 2,2¢-bipyridine (Bpy). The colored complex of [Fe(Bpy) 3 ] 2+ was formed in sodium dodecyl sulfate (SDS) as micellar media, and then monitored at 520 nm. The results showed that simultaneous determination of HZ, TSCZ and PHZ could be performed in their concentration ranges of 1.0-70.0, 0.2-6.0 and 0.1-10.0 µg mL -1 , respectively. The root mean squares errors of prediction (RMSEP) of HZ, TSCZ and PHZ were 0.719, 0.164 and 0.105 (for PLS) 0.788, 0.166 and 0.993 (for PCR), respectively. Both methods (PCR and PLS) were validated using a set of synthetic sample mixtures and then applied for simultaneous determination of HZ, TSCZ and PHZ in water samples. Apparatus and SoftwareA GBC UV-Visible Cintra 6 Spectrophotometer model with 1-cm glass cells was used for recording the kinetic spectrophotometric data. A Metrohm 780 pH-meter furnished with a combined glass-saturated calomel electrode was calibrated with at least two buffer solutions at pH 3.00 and 9.00. The data were treated in an AMD 2000 XP (256 Mb RAM) microcomputer using MATLAB software. PLS and PCR analyses were performed using PLS and PCR toolboxes in MATLAB program version 7.0. Reagents and Standard SolutionsAll chemicals were of analytical reagent grade and double distilled water was used throughout experiments. Stock solutions (1000 µg mL -1 ) of HZ, TSCZ and PHZ were prepared in 100-mL flasks by dissolving 0.4061 g of hydrazinium sulfate (Merck), 0.1000 g of thiosemicarbazide (Merck) and 0.1337 g of phenylhydrazinium choloride (Merck) in water and diluting with water to the mark. A 0.05 M Fe(III) solution was prepared in a 100-mL flask by dissolving 2.43 g of ammonium ferric sulfate in water and diluting to the mark. 2,2¢-Bipyridine (Bpy) solution (0.05 M) was prepared by dissolving 0.784 g of 2,2¢-bipyridine (Merck) in ethanol and diluting with water to 100-mL in a volumetric flask. A 0.2 M SDS solution was prepared by dissolving 5.76 g of SDS (Merck) in water and diluting to 100-mL with water. Acetate buffer solution (1.0 M, pH 3.0) was prepared using acetic acid and NaOH solutions and adjusting its pH with a pH meter.

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