Spectrophotometric flow-injection determination of sulphite in white wines involving gas diffusion through a concentric tubular membrane

A flow-injection system is proposed for the spectrophotometric determination of sulphite in white wines. The method involves analyte conversion to SO2, gas diffusion through a Teflon® semi-permeable membrane, collection into an alkaline stream (pH 8), reaction with Malachite green (MG) and monitoring at 620 nm. With a concentric tubular membrane, the system design was simplified. Influence of reagent concentrations, pH of donor and acceptor streams, temperature, timing, surfactant addition and presence of potential interfering species of the wine matrix were investigated. A pronounced (ca. 100%) enhancement in sensitivity was noted by adding cetylpyridinium chloride (CPC). The proposed system is robust and baseline drift is not observed during 4 h operating periods. Only 400 μL of sample and 0.32 mg MG are required per determination. The system handles 30 samples per hour, yielding precise results (r.s.d. < 0.015 for 1.0 - 20.0 mg L-1 SO2) in agreement with those obtained by an alternative procedure.

The dermatophyte Trichophyton rubrum secretes an EDTA-sensitive alkaline phosphatase on high-phosphate medium

In this communication, we show that the growth of isolate H6 of the dermatophyte Trichophyton rubrum on non-buffered medium and under saturating phosphate conditions is dependent on the initial growth pH, with an apparent optimum at pH 4.0. In addition, irrespective of the initial growth pH, the pH of the medium altered during cultivation reaching values that ranged from 8.3 to 8.9. Furthermore, this isolate synthesized and secreted almost the same levels of an alkaline phosphatase with an apparent optimum pH ranging from 9.0 to 10.0 when grown on both low- and high-phosphate medium. Also, this alkaline phosphatase is activated by Mg2+ and is EDTA-sensitive. On the other hand, the very low levels of the enzyme retained by the mycelium grown on buffered medium at pH 5.0-5.2 suggest that this enzyme is encoded by an alkaline gene, i.e., a gene responsive to ambient pH signaling.

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.

Physiological responses of broiler chickens to heat stress and dietary electrolyte balance (sodium plus potassium minus chloride, milliequivalents per kilogram)

Individually caged male Cobb broilers (24), 44 d of age, were used to evaluate effects of heat stress (1 d of data collection) and dietary electrolyte balance (DEB; Na + K - Cl, mEq/kg from 1 d of age). During summer rearing, mortality was variable, but DEB 240 improved growth, feed conversion ratio, water intake, and waterrfeed ratio vs. DEB 0. The temperature sequence for heat stress was 24 to 32°C in 30 min, 32 to 36°C in 30 min, 36 to 37°C in 15 min, and 37 to 41°C in 45 min. Maximum temperature was held for 15, 60, 90, or 360 min for data collection (relative humidity averaged 42 ± 7%). Results from the same room before and after heat stress were analyzed by DEB (1-factor ANOVA) and before vs. after heat stress compared across DEB (2-sample t-test). Heat stress decreased blood Na, K, and pCO2, and lymphocytes but increased heterophils. Blood HCO3 rose, Cl declined, and hematocrit gave a concave pattern (lowest at DEB 120) as DEB increased. After heat stress, DEB O decreased blood Na and K, and DEB O and 120 levels decreased blood HCO3. After heat stress blood pCO2 and hemoglobin decreased with DEB 240, but it had highest pCO2, a key factor. The DEB 120 gave longest times to panting and prostration with DEB O and 240 results lower but similar statistically. In heat stress, DEB 360 was excessive, DEB 120 and 240 were favorable, and DEB 0 was intermediate based on hematology, panting, and prostration responses.

Determination of calcium by atomic absorption spectrophotometry applied to the preparation of alginate:chitosan complexes

Polysaccharicles, as alginate and chitosan, have been used to obtain modified release dosage forms. Alginate, due to its property of building gels during the complex formation with calcium ions, allows the building of capsules containing a core constituted by calcium alginate. This work had for objective to determine the appropriate calcium concentration for the preparation of alginate-chitosan capsules, by means of calcium quantification using atomic absorption spectrophotometry. The methodology of calcium quantification was validated through analysis of the limit of detection, precision, accuracy and recovery of the method. The capsules, containing or not the drug, were prepared by the complex coacervation/ionotropic gelification method. Calcium was quantified after samples mineralization and dilution in lantanium solution. The results showed that the amount of calcium incorporated into the capsules depends on the amount of calcium added to the medium, and this ratio increases until the concentration of 1.5% of initial calcium chloride and above this concentration there is a decrease in the proportion of calcium bonded. It was observed that the proportion of calcium that links to the polymer is inversely proportional to the amount of calcium added. The calcium amount incorporated depends on the concentration of the polymeric dispersions used as well as on the ratio between the two polymers.

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.

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)

Production and partial characterization of keratinase produced by a microorganism isolated from poultry processing plant wastewater

A Streptomyces was isolated from poultry plant wastewater, showed high keratinolytic activity when cultured on feather meal medium. Optimum keratinolytic activity was observed at 40°C and pH 8.0. The enzyme also showed to be stable between 40 and 60°C. The keratinolytic activity was not inhibited by EDTA, DMSO and Tween 80. On the other hand, CaCl2, ZnCl2, and BaCl2 slightly inhibited the keratinolytic activity. The Streptomyces isolated might be useful in leather, keratin waste treatment, animal feeding industry, and also cosmetic industry. © 2008 Academic Journals.

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)

Recurrent urinary tract infections: Evaluation of the prophylactic efficacy of urinary antiseptics methenamine and methylthioninium chloride

Introduction: Urinary tract infection (UTI) is a very common condition in clinical practice, affecting an estimated 50% of all adult women during a lifetime. The most common causative agent is E. coli; UTI may also be caused by S. saprophyticus, Enterobacteria (Klebsiella sp and Serratia sp.), Enterococcus sp., and P aeruginosa. Recurrent UTIs occur at least twice per semester or three times a year. Prophylactic measures to prevent recurrent UTIs include changes in contraception methods, cranberry products, increased fluid intake, urination after intercourse, vaginal estrogen therapy for post-menopausal women, antibiotics, and urinary tract antiseptic agents. Objectives: To evaluate the use of a combination of methenamine and methyl-thioninium chloride in the prophylaxis of recurrent uncomplicated lower UTIs, with respect to: • Signs and symptoms of UTI • Etiologic agent(s) • Recurrence rates • Need for antibiotic therapy in case of recurrence • Incidence of adverse events associated with the treatment, including any reported alterations of laboratory tests Materials & methods: A descriptive, analytic, restrospective study was performed at Hospital Universitário Constantino Otaviano - UNIFESO. Medical charts from patients presenting recurrent uncomplicated lower UTI attended from 2001-present were analyzed, including the following information: Demographic data (age, gender, weight, ethnicity, living conditions): medical history/signs and symptoms of UTI; identification of treatment and dosing regimens; treatment duration; recurrence rates and need for antibiotic therapy in case of recurrence; other medications prescribed; and records of adverse events. Results: E. coli was identified as etiologic agent in 80% of the patients. Following antibiotic therapy, all patients received prophylactic treatment with the combination of methenamine and methylthioninium chloride. Treatment duration ranged from three to six months. Adverse events were observed in 13/60 patients (21.7%). At the end of the respective treatment periods, a statistically significant (p<0.0001) number of patients showed no UTI recurrence. Conclusion: Based on the results from the collected data, we conclude that an orally administered combination of methenamine and methylthioninium chloride is safe and effective in the prophylactic treatment of recurrent uncomplicated lower urinary tract infection. © Copyright Morelra Jr. Editora.

The role of coarse intermetallics in the localized corrosion behaviour of AA 2024-T3 in low concentrated chloride media

Aluminium alloy (AA) 2024-T3 is an important engineering material due to its widespread use in the aerospace industry. However, it is very prone to localized corrosion attack in chloride containing media, which has been mainly associated to the presence of coarse intermetallics (IMs). In this work the corrosion behaviour of aluminium alloy 2024-T3 in low concentrated chloride media was investigated using microscopy and electrochemical methods. SEM observations have shown that intermetallics with the same nominal composition present heterogeneous reaction rates, and that both types of coarse IMs normally found in the AA 2024-T3 microstructure corrode. Moreover, EDS analyses have shown important compositional changes in the corroded IMs, evidencing the selective corrosion of their more active constituents and the onset of an intense oxygen peak, irrespective to the IM nature. TEM/EDS observations on non-corroded samples have evidenced the heterogeneous composition within the IMs. On the other hand, the results of the electrochemical investigations, in accordance with the SEM/EDS observations, have evidenced that IMs corrosion dominates the electrochemical response of the alloy during the first hours of immersion in the test electrolyte. © 2009 by NACE International.

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.