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111.
Ernesto Prado Lopes José Roberto Linhares de Mattos 《Proceedings of the American Mathematical Society》2008,136(6):2201-2207
We consider the problem , , , where is bounded below by a positive constant. The solution on the boundary is a known function and . This is an ill-posed problem in the sense that a small disturbance on the boundary specification can produce a big change in its solution, if it exists. In a previous work, we used a Wavelet Galerkin Method with the Meyer Multiresolution Analysis to generate a sequence of well-posed approximating problems to it. In the present work, by assuming that is Lipschitz, we are able to prove that the existence of a solution , for this problem, implies its uniqueness.
112.
Hexagonal mesoporous silica modified with copper phthalocyanine as a photocatalyst for pesticide 2,4-dichlorophenoxiacetic acid degradation 总被引:1,自引:0,他引:1
DeOliveira E Neri CR Ribeiro AO Garcia VS Costa LL Moura AO Prado AG Serra OA Iamamoto Y 《Journal of colloid and interface science》2008,323(1):98-104
A new mesoporous catalyst was prepared by the reaction between 3-aminopropyltrimethoxisylane and Cu(II)-hexadecafluorophthalocyanine, followed by co-condensation of tetraethylorthosilicate around a micelle formed by n-dodecylamine. The surfactant was removed from the pores by continuous extraction with ethanol, giving the Si-CuF16Pc catalyst. This catalyst was characterized by SEM, FTIR, TGA, 29Si NMR, N2 adsorption and X-ray diffraction. SEM images confirmed that the catalyst material is formed by nanoaggregates with a diameter of 100 nm. N2 adsorption isotherms showed that Si-CuF16Pc has a surface area of approximately 200 m2 g(-1) and a porous diameter of 7.7 nm, characterizing the mesoporosity of this product. This novel material shows an excellent photocatalytic activity, degrading almost 90% of 2,4-dichlorophenoxyacetic acid (2,4-D) up to 30 min, while only approximately 40% of photodegradation was obtained in its absence. 相似文献
113.
Tolosa J Romero-Nieto C Díez-Barra E Sánchez-Verdú P Rodríguez-López J 《The Journal of organic chemistry》2007,72(10):3847-3852
The efficient synthesis of new asymmetric poly(phenylenevinylene) dendritic macromolecules using a stepwise convergent-growth approach is described. By an iterative methodology that made use of the Horner-Wadsworth-Emmons (HWE) reaction, dendrons and dendrimers up to the third generation, with eight different functional groups located at the periphery, were prepared in good yields. Both the number and placement of functionalities can be accurately controlled to afford a large variety of dendritic architectures. 相似文献
114.
Takahashi HT Novello CR Ueda-Nakamura T Filho BP Palazzo de Mello JC Nakamura CV 《Molecules (Basel, Switzerland)》2011,16(5):3469-3478
Porophyllum ruderale (Jacq.) Cass. is a plant native to Brazil and in the northwest region of the state of Paraná, Brazil, aerial parts of P. ruderale have been used popularly in the treatment of lesions caused by Leishmania sp.. In this study the antileishmanial and cytotoxic activities of the crude extract, fractions, and isolated compounds from aerial parts of P. ruderale was evaluated. The dichloromethane extract was submitted to chromatography to yield compounds active against Leishmania amazonensis. Their structures were established by comparison of their spectroscopic data with literature values. The activities of crude extract against promastigote and axenic amastigote forms of L. amazonensis (IC(50)) were 60.3 and 77.7 μg/mL, respectively. Its cytotoxic activity against macrophage cells (CC(50)) was 500 μg/mL. The thiophene derivatives isolated were: 5-methyl-2,2':5',2"-terthiophene (compound A) and 5'-methyl-[5-(4-acetoxy-1-butynyl)]-2,2'-bithiophene (compound B). The activity of compound A against promastigote and axenic amastigote forms were 7.7 and 19.0 μg/mL and of compound B were 21.3 and 28.7 μg/mL, respectively. The activity of the isolated compounds against promastigote and axenic amastigote forms was better than that of the crude extract and more selective against protozoa than for macrophage cells. 相似文献
115.
A. Caneiro L. Mogni N. Grunbaum F. Prado 《Journal of Thermal Analysis and Calorimetry》2011,103(2):597-606
One of the most important challenges with solid oxide fuel cells (SOFC) is to find cathode materials with high enough catalytic
activity for the dissociation of the molecular oxygen. Oxide mixed conductors with the perovskite structure (ABO3) and high Co content in the B site have been extensively studied to be used as cathode in SOFC. This is the second part of
a review of high temperature properties of two mixed conductors systems. The first part was focused on the n = 2 Sr3FeMO6+δ (M = Fe, Co, Ni) Rudlesdden Popper phases, while in this paper we discuss the thermodynamic and transport properties of the
perovskite solid solution Sr1−x
La
x
Fe0.2Co0.8O3−δ (0 ≤ x ≤ 0.4) in the temperature range 773 ≤ T ≤ 1173 K. In particular, the interest has been focused on the x = 0 sample, which exhibits large ionic conductivity values (σi ~1 S cm−1), but suffers a structural transformation from cubic to orthorhombic symmetry because the ordering of the oxygen vacancies
when the oxygen partial pressure decreases. Measurements of the oxygen chemical potential (
m\textO2 \mu_{{{\text{O}}_{2} }} ) as function of oxygen content and temperature, coupled with high temperature X-ray diffraction data, permitted us to broaden
the knowledge of the T–δ–p(O2) phase diagram for the x = 0 sample. In addition, we have investigated the effects of the La incorporation on the stability range of the cubic phases
of the Sr1−x
La
x
Fe0.2Co0.8O3−δ solid solution. 相似文献
116.
Alexandre G. S. Prado Sheila M. Evangelista Jurandir R. SouzaDe Jeane G. S. Matos Marco A. A. Souza Denise A. Oliveira Claudio Airoldi 《Journal of Thermal Analysis and Calorimetry》2011,106(2):431-436
A microcalorimetric method was applied to study microbial soil activity of ornamental flower (Dahlia pinnata) plantations when irrigated with potable water and wastewaters. The samples were irrigated with potable water PW sample (reference)
and treated wastewaters from Municipal Wastewater Treatment Station of Asa Norte in Brasilia City (Brazil). Three different
water treatments were applied to irrigate soil samples, named TW1, TW2, and TW3 samples. The increase of the microbial soil
activity observed in TW1 sample must have occurred because of the high amount of organic waste dissolved in wastewater used
for irrigation. This rise indicates that the present treated wastewater can affect natural life cycle. However, only a low
alteration in microbial soil activity was observed in the TW2 and TW3 samples, which suggests that these wastewater treatments
can be normally used to irrigate soils without bringing environmental consequences, once they offer a great opportunity to
upgrade and protect the environment. 相似文献
117.
118.
Alexandre G. S. Prado R?mulo D. A. Andrade Jez W. B. Braga Paulo A. Z. Suarez 《Journal of Thermal Analysis and Calorimetry》2012,110(2):865-872
Biofuel has been obtained by cracking of soybean (Glycine sp.) oil, which is characterized by acidity index, density, cetane index, copper corrosion, carbon residue, fulgor point, and heat of combustion. In order to evaluate the quality of biofuel as well as detect its adulteration with vegetable oil, partial least squares regression calibration models based on thermogravimetric (TG) analysis were used as a precise and an accurate method. Thirty mixtures of biofuel/diesel/vegetable oil standards were prepared. Twenty of them were used for calibration, and ten for validation. The results have shown that the thermogravimetric analysis, PLS/TG, presented the best performance for the detection of vegetable oil contamination with a root mean square error of prediction (RMSEC% w/w) of 0.23, with a relative error of prediction of 3.6%, corroborating with the success of TG analysis application to determine the quality of biofuels and diesel/biofuel blends, showing that the TG analysis is an excellent tool to control quality of biofuels. 相似文献
119.
The development of DNA-based methods for the identification and quantification of fish in food and feed samples is frequently focused on a specific fish species and/or on the detection of mitochondrial DNA of fish origin. However, a quantitative method for the most common fish species used by the food and feed industry is needed for official control purposes, and such a method should rely on the use of a single-copy nuclear DNA target owing to its more stable copy number in different tissues. In this article, we report on the development of a real-time PCR method based on the use of a nuclear gene as a target for the simultaneous detection of fish DNA from different species and on the evaluation of its quantification potential. The method was tested in 22 different fish species, including those most commonly used by the food and feed industry, and in negative control samples, which included 15 animal species and nine feed ingredients. The results show that the method reported here complies with the requirements concerning specificity and with the criteria required for real-time PCR methods with high sensitivity. 相似文献
120.
Michelle Miranda A. C. Ribeiro Aliceana A. Prado Alex Domingues Batista Rodrigo Alejandro Abarza Munoz Eduardo Mathias Richter 《Journal of separation science》2019,42(3):754-759
Ascorbic acid and zinc are essential nutrients that play important roles in nutrition, immune support, and maintenance of health. For this reason, both compounds are widely used as ingredients in dietary supplements. We report, for the first time, an analytical method for fast simultaneous determination of ascorbic acid and zinc. A single analysis run is possible every 80 s (45 injections/h). The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection using a fused silica capillary with 50 cm length (effective length of 10 cm). The separation was achieved by using a background electrolyte composed by 30 mmol/L of 2‐(morpholin‐4‐yl)ethane‐1‐sulfonic acid and 30 mmol/L of histidine, pH 6.1. The detection limits were 10 and 20 μmol/L and recovery values for spiked samples were 101 and 100% for zinc and ascorbic acid, respectively. The results obtained with the developed procedure were compared to those obtained by titration (ascorbic acid) and flame atomic absorption spectroscopy (zinc), and no statistically significant differences were observed (95% confidence level). 相似文献