Determination of Cu, Ni and Pb in Aqueous Medium by FAAS after Pre-Concentration on 2-Aminothiazole Modified Silica Gel

This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT), and the results of a study of the adsorption and pre-concentration (in batch and using a flow-injection system coupled to an absorption atomic spectrometer) of Cu(II), Ni(II) and Pb(II) in aqueous medium. The adsorption capacities for each metal ions in mmol g -1 were: Cu(II)= 1.18, Ni(II)= 1.15 and Pb(II)= 1.10. The results obtained in the flow experiments showed a recovery of practically 100% of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 μL of 2.0 mol L -1 HCl solution as eluent. The sorption-desorption of the metal ions made possible the application of a flow-injection system for the pre-concentration and quantification by FAAS of metal ions at trace level in natural water samples digested and not digest by an oxidizing UV photolysis.

Electrochemical reduction and voltammetric determination of diloxanide furoate in non-aqueous medium

The electrochemical reduction of diloxanide furoate (DF) in acetonitrile on glassy carbon electrode was studied in this work. It was observed that DF is reduced after a reversible one-electron transfer followed by an irreversible chemical reaction, diagnosed as C-Cl bond cleavage. Its reduction was followed by linear (LSV), differential pulse (DPV) and square wave voltammetry (SWV). Analytical curves were obtained for DF determination using all the investigated voltammetric techniques. For LSV was obtained a linear range (LR) from 5.0 × 10-4 to 1.0 × 10-2 mol L-1, with detection limit (DL) of 1.5 × 10-4 mol L-1 and sensitivity (S) of 2.1 × 104 μA mol-1 L. The analytical parameters obtained by DPV were: LR = 5.0 × 10-4 to 2.2 × 10-3 mol L-1, DL = 7.8 × 10-5 mol L-1, S = 3.7 × 104 μA mol-1 L. For SWV were obtained a LR = 7.5 × 10-6 to 1.2 × 10 -3 mol L-1, DL = 5.5 × 10-6 mol L -1 and S = 2.8 × 105 μA mol-1 L. Thus, the SWV was the most sensible technique, which can be used for DF determination at low concentration levels. Statistics methods were used to evaluate the analytical procedure, where recovery around to 100% was obtained for all voltammetric techniques. Relative standard deviations were lower than 5.0% (N=5). The obtained t values evaluating all the three voltammetric methods were less than the tabulated ones, indicating that there are no evidences of systematic error. ©2005 Sociedade Brasileira de Química.

Influence of chromate, molybdate and tungstate on pit formation in chloride medium

It has been characterized and evaluated the 2024-T351 and 7050-T7451 aluminum alloys pitting corrosion in naturally aerated chloride aqueous solutions containing chromate, molybdate and tungstate. It has been carried out electrochemical and non-electrochemical immersion corrosion tests accompanied by surface metallography analysis using an optical microscopy. Chromate for the two alloys and in molybdate for 7050 has corrosion inhibiting effects, whereas tungstate promotes the pitting corrosion for these alloys. Quantitative surface analysis upon the alloys after immersion has indicated that pits are predominantly conical or quasi-conical and irregular. In general, pits have been wider than deep and the widest have been also the deepest. Despite inhibitor presence, when pits have been nucleated, they grow with the same intensity. © 2005 Elsevier B.V. All rights reserved.

Automated extraction of road network from medium-and high-resolution images

This paper presents an automatic methodology for road network extraction from medium-and high-resolution aerial images. It is based on two steps. In the first step, the road seeds (i.e., road segments) are extracted using a set of four road objects and another set of connection rules among road objects. Each road object is a local representation of an approximately straight road fragment and its construction is based on a combination of polygons describing all relevant image edges, according to some rules embodying road knowledge. Each road seed is composed by a sequence of connected road objects in which each sequence of this type can be geometrically structured as a chain of contiguous quadrilaterals. In the second step, two strategies for road completion are applied in order to generate the complete road network. The first strategy is based on two basic perceptual grouping rules, i.e., proximity and collinearity rules, which allow the sequential reconstruction of gaps between every pair of disconnected road segments. This strategy does not allow the reconstruction of road crossings, but it allows the extraction of road centerlines from the contiguous quadrilaterals representing connected road segments. The second strategy for road completion aims at reconstructing road crossings. Firstly, the road centerlines are used to find reference points for road crossings, which are their approximate positions. Then these points are used to extract polygons representing the contours of road crossings. This paper presents the proposed methodology and experimental results. © Pleiades Publishing, Inc. 2006.

Enhanced photocatalytic reduction of Hg(II) in aqueous medium by 2-aminothiazole-modified TiO2 particles

This work describes the synthesis and characterization of 2-aminothiazole-modified titania and its application on Hg (II) photoreduction in aqueous medium. Infrared spectroscopy confirmed the chemical modification of the titania matrix. The number of 2-aminothiazole groups attached to the titania was determined by Kjeldahl's method. The photocatalytic experiments were carried out in a cylindrical photoreactor thermostatted at 298 K. The resulting modified photocatalyst 2-aminothiazole titania (TiAT) revealed an enhance in the Hg (II) photoreduction capacity at studied pH values (3, 7 and 9). In addition, sorption studies showed that the photocatalyst TiAT presented a lower equilibrium time and a higher sorption capacity of Hg(II) ion, demonstrating that sorption plays a fundamental role in the photoreduction mechanism. ©2006 Sociedade Brasileira de Química.

Medium-term tongue carcinogenesis assays: A comparative study between 4-nitroquinoline 1-oxide (4NQO)-induced rat and dimethylbenzanthracene (DMBA)-induced hamster carcinogenesis

The most used animal models in oral cancer research are the hamster treated by dimethylbenzanthracene (DMBA), and the rat treated by 4-nitroquinoline 1-oxide (4NQO). The purpose of this study was to compare the DMBA-induced hamster tongue carcinogenesis and 4NQO-induced rat tongue carcinogenesis by means of morphological analysis. Male Wistar rats were distributed into three groups of ten animals each and treated with 50 ppm 4NQO solution by drinking water for 4, 12 or 20 weeks. A total of 18 Syrian golden hamsters were submitted to 0.5% DMBA (dissolved in acetone) topical application three times/week for 4, 12 and 20 weeks. The primary histopathological change i.e., hyperplasia and hyperkeratosis, was evidenced after 4 weeks treatment with DMBA. Regarding 12 weeks treatment, 4NQO and DMBA were able to induce morphological changes as depicted by hyperplasia and dysplasia. At 20 weeks, squamous cell carcinoma was found in the majority of animals for both carcinogens used. Taken together, our results suggest that the hamster experimental model disclosed aspects related with tongue carcinogenesis in lesser time than rats. Probably, such discrepancies depend strongly on route of administration and the susceptibility with respect to animal species. © 2006 Elsevier GmbH. All rights reserved.

Bio-safety technology in production of bovine herpesvirus type 5 (BoHV-5) using an alternative serum-free medium

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

Application of a serum/protein-free medium for the growth of mammalian cell lines and high level production of classical, variant and very virulent strain of infectious bursal disease virus (IBDV)

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

Semi-selective culture medium for Xanthomonas axonopodis pv. malvacearum detection in cotton seeds (Gossypium hirsutum L.)

The cotton disease known as angular leaf spot, caused by Xanthomonas axonopodis pv. malvacearum (Xam) has been causing cotton losses in several producing regions around the world. Xam is transmitted by seeds, which may be infected both externally and internally. Infected seeds constitute the main long-distance dissemination mode of the pathogen. In view of this, the use of healthy seeds is a must. To accomplish that, detection methodologies for the bacteria must be developed be used in seed health analysis laboratories. This study aimed to develop a semi-selective medium for Xam detection in cotton seeds. The semi-selective culture medium was named MSSXAN and it was consisted of peptone (5.0 g), beef extract (3 g), sucrose (5 g), soluble starch (10 g), agar (15 g), CaCl 2 (0.25 g), Tween 80 (10 mL), distilled water (1,000 mL), crystal violet solution at 1% (150 μL), cephalexin (50 mg 1*), methyl thyophanate (10 mg*) and chlorothalonil (10 mg*) - *added after culture medium autoclaving. This MSSXAN medium shows low repressiveness to Xam and it be used for isolation of this bacteria in cotton seeds health analysis. © 2009 Academic Journals Inc.

Influence of medium composition in the production of ethanol by Zymomonas mobilis

The production of ethanol using Zymomonas mobilis had been reported to be three to four times larger than with Saccharomyces cereviseae. The influence of pH, temperature and composition of the means of fermentation are parameters that can direct the metabolism for the production of ethanol. The objective of this study was to evaluate the production of ethanol by Zymomonas mobilis CCT 4494, by variations of the initial pH, temperature and concentrations KCl, K 2SO4, MgSO4, CaCl2 and sucrose, by a factorial experimental design of type 27-2, according to the model proposed by Box et al. (1978). For this, the broth of sugar cane was used as sole carbon source, because it is cheap and easily accessible in the region of São José do Rio Preto, São Paulo State. According to the experimental design, the bacteria Zymomonas mobilis CCT 4494 has adapted in the fermentation mean containing high concentrations of sucrose, and supported the change of pH and temperature of fermentation. The highest amount of ethanol produced was 8.89 mg mL-1. This is not similar to the levels of secondary metabolites produced by Zymomonas mobilis CCT 4494.

Brazilian experience with the medium-term multi-organ bioassay: Scientific and regulatory developments

In 1996 the Brazilian Institute for the Environment (IBAMA) officially adopted a variation of the multiorgan initiation-promotion DMBDD bioassay as a valid source of evidence of the carcinogenic potential of pesticides. The protocol adopted by IBAMA was a modification of the one originally proposed by researchers led by Nobuyuki Ito, from the Nagoya City University Medical School. Among the modifications established in the Brazilian protocol were the use of both sexes of the outbreed Wistar strain of rats and two positive control test chemicals. The adoption of the modified DMBDD protocol was instrumental during the last decade for qualifying technical people and to spread knowledge on chemical carcinogenesis in Brazil.

Sperm motility of Prochilodus lineatus in relation to dilution rate and temperature of the activating medium

The objective of this study was to assess the effects of an activating solution on the sperm motility duration (SMD) of 'curimbatá', Prochilodus lineatus through of the definition of qualitative and quantitative parameters of the semen pool used in the experiment; evaluation of the effects of different ratios of semen dilution corresponding to 1-:-1, 1-:-2, 1-:-20, 1-:-200, 1-:-2000, 1-:-20-000 and 1-:-100-000 semen:dilute solution on the SMD and, assessment of the effects of different temperatures of the activating solution (5, 10, 15, 20, 25, 30, 35, 40, 45 and 50°C) on the SMD. The results of SMD were directly proportional to the dilution (P<0.05), starting from the dilution of 1-:-2 (semen:water), with 23.04-s. Were used three replicates of the semen pool for each test. Two-year-old brookstock were maintained in ponds culture conditions. In November-December 2006, twelve mature males broodfish were selected (mean weight and length of 405.8±134.2-g and 25.6±3.1-cm, respectively). The males released that semen under slight pressure of the urogenital papilla were selected for the experiment. The SMD increased proportionally to the increase in dilution, until it reached a maximum of 28.83-s for the ratio 1-:-100-000 semen: dilute solution. The results of SMD in relation to the temperature of the activating solution exhibited a quadratic behavior (P<0.05) with a maximum theoretical performance in terms of sperm motility duration of 21.36-s at a temperature of 17.3°C. Thus, for the species considered, the increase in the dilution ratio proved favorable for the rise in motility duration until the maximum value studied of 1-:-100-000 semen:dilute solution. As for the temperature of the activating solution, the best results of SMD were obtained at the temperature of 17.3°C. At higher temperatures used in the experiment (25, 30, 35, 40, 45 and 50°C), a decrease in motility duration. © 2010 Blackwell Verlag, Berlin.

Information technology for development of small and medium-sized exporters in Latin America and East Asia

Includes bibliography

Information and communication technology (ICT) for development of small and medium-sized exporters in Latin America: Chile

Includes bibliography

Information and communication technology (ICT) for development of small and medium-sized exporters in Latin America: Colombia

Includes bibliography