Efeitos alelopaticos de alguns extratos vegetais na germinação do tomateiro (Lycopersicon esculentum Mill. cv. Santa Cruz)

O presente trabalho teve por finalidade avaliar os possíveis efeitos alelopáticos de três plantas daninhas (Cyperus rotundus, Sorghum halepense e Cynodon dactylon), uma leguminosa (Canavalia ensiformis) e colza (Brassica napus), na germinação das sementes do tomateiro (Lycopersicon esculentum cv. Santa Cruz) utilizado como indicador. Tubérculos de tiririca, rizomas de capim massambará, o sistema radicular de grama seda, além de folhas e raízes de feijão-de-porco e colza, foram homogeneizados em solução aquosa, submetidos a filtração e centrifugação. A aplicação do sobrenadante no substrato de germinação das sementes de tomateiro mostrou afetar o processo germinativo e o desenvolvimento da radícula e do hipocótilo. C. rotundus, S. halepense e raízes de C. ensiformis possuem substâncias altamente inibitórias à germinação do tomateiro 'Santa Cruz'', sendo que a planta indicadora também mostrou-se sensível às substâncias presentes nas folhas de B. napus e em C. dactylon.

Efeito da centrifugação sobre a qualidade do sêmen canino

Avaliou-se o efeito da centrifugação sobre a viabilidade do sêmen canino e compararam-se três meios de diluição pré-centrifugação. Utilizaram-se 10 ejaculados completos de 10 cães que, após a avaliação inicial, foram divididos em quatro porções (grupos). Uma das amostras, não centrifugada, formou o grupo-controle; as outras foram diluídas em três diferentes meios e centrifugadas a 800 x g por 15 minutos, formando os grupos: CPSA - constituído por sêmen centrifugado em plasma seminal autólogo; CLG - sêmen centrifugado em meio à base de leite desnatado e glicose (LG); e CPer- sêmen centrifugado em gradientes de Percoll (45% e 90%). Após a centrifugação e a eliminação do sobrenadante, procedeu-se à ressuspensão de todas as porções do ejaculado em LG e à imediata avaliação quanto à motilidade, vigor, aglutinação espermática e integridade das membranas espermáticas. Todas as suspensões foram, então, incubadas a 37ºC por 30 minutos e reavaliadas. O processo de centrifugação não causou danos aos espermatozoides e a centrifugação em meio LG melhorou a viabilidade espermática.

Floculação de leveduras por Lactobacillus fermentum em processos industriais de fermentação alcoólica avaliada por técnica fotométrica

Na produção de álcool por fermentação com leveduras, a floculação manifesta-se como um mecanismo natural de agregação de células. Essa condição pode ser induzida por vários fatores, entre eles, a interação entre bactérias floculentas como Lactobacillus fermentum e as leveduras. Esse fato torna-se prejudicial para o processo, pois tanto nas unidades que se utilizam do sistema de recuperação de células por centrifugação, como nas que não o utilizam, ocorrem perdas excessivas de fermento, em conseqüência dos problemas operacionais decorrentes da floculação, comprometendo seriamente o desempenho industrial. No presente trabalho, avaliou-se a floculação em vinho proveniente de fermentação experimental, sob duas condições de pH de fermento tratado utilizadas como inóculo e temperaturas de fermentação, não se observando diferenças significativas entre elas. Com este estudo, pôde-se ainda avaliar a capacidade de dispersão dos flocos em três condições de pH no tratamento do fermento em fase industrial, mostrando diferenças altamente significativas entre elas. A maior capacidade de dispersão no tratamento do fermento é desejável para o controle da floculação industrial, permitindo a sua centrifugação, com conseqüente separação das bactérias contaminantes do fermento. Essas constatações tornaram-se possíveis pelo emprego da técnica usual de determinação da floculação por espectrofotometria, modificada pela desfloculação prévia das amostras de vinho e fermento, o que conferiu maior estabilidade nas leituras.

Simulation and economic analysis of bovine sex selection

A simulation model implemented in the programming software Delphi XE® was applied to evaluate sex selection in bovine. The hypothesis under investigation was that a dynamic model with stochastic and deterministic elements could detect the sexed semen technique to minimize pregnancy cost and to determine the adequate number of recipients required for in vivo (ET) and in vitro embryo production (IVP) in the proposed scenarios. Sex selection was compared through semen sexed using flow cytometry (C1) and density gradient centrifugation techniques (C2) in ET and IVP. Sensibility analyses were used to identify the adequate number of recipients for each scenario. This number was reinserted into the model to determine the biological and financial values that maximized ET and IVP using sexed semen (C1M and C2M). New scenarios showed that the density gradient technique minimized pregnancy cost based on the proposed scenarios. In addition, the adequate number of recipients (ET - C1M - 115 and C2M - 105)/(IVP - C1M - 145 and C2M - 140) per donor used was determined to minimize the pregnancy cost in all scenarios.

Evaluation of a novel kit (TF-test) for the diagnosis of intestinal parasitic infections

Intestinal parasitic infections are currently a source of concern for Public Health agencies in developing and developed countries. Since three ovum-and-parasite stool examinations have been demonstrated to provide sensitive results, we designed a practical and economical kit (TF-Test) that is now commercially available (Immunoassay Com. Ind. Ltda., S (a) over tildeo Paulo, Brazil). This kit allows the separate collection of three fecal specimens into a preservative solution. The specimens are then pooled, double-filtered, and concentrated by a single rapid centrifugation process. The TF-Test was evaluated in four different laboratories in a study using 1,102 outpatients and individuals living in an endemic area for enteroparasitosis. The overall sensitivity found using the TF-Test (86.2-97.8%) was significantly higher (P<0.01) than the sensitivity of conventional techniques such as the Coprotest (NIL Comercio Exterior Ltda, São Paulo, Brazil) and the combination of Lutz/Hoffman, Faust, and Rugai techniques (De Carli, Diagnostico Laboratorial das Parasitoses Humanas. Metodos e Tecnicas, 1994), which ranged from 48.3% to 75.9%. When the above combined three specimen technique was repeated with three specimens collected on different days, its sensitivity became similar (P > 0.01) to that of the TF-Test. The kappa index values of agreement for the TF-Test were consistent (P < 0.01), being higher and ranking in a better position than conventional techniques. The high sensitivity, cost/benefit ratio, and practical aspects demonstrate that the TF-Test is suitable for individual diagnosis, epidemiological inquiries, or evaluation of chemotherapy in treated communities. (C) 2004 Wiley-Liss, Inc.

Determination of the betaine content of feed ingredients using high-performance liquid chromatography

A series of studies was conducted to establish a methodology for the accurate and efficient determination of betaine in different feed ingredients. The final methodology involves an extraction step in which the feed sample is heated for 3h in a methanolic KOH solution using a Goldfisch apparatus. Impurities are removed by the addition of activated charcoal and concentrated (36%) HCl. After centrifugation the extractant is passed through a strong cation exchange resin (Dowex 50W-X12, H+). The betaine retained in the column is eluted with 1.5 N HCl. A 2 nil aliquot of the elute is air dried and reconstituted with 1 ml of deionised water. HPLC separation with a cation exchange column (Partisil SCX-10) is used for the separation of betaine from other compounds. The mobile phase is kept constant at 50mm KH2PO4 in water, and eluted compounds are detected by UV absorbance (200nm). The flow rate is maintained at 1.5ml min(-1). This assay is very accurate over the range of betaine concentrations from 15 to 650 mug ml(-1), with a lower detection limit in feeds of approximately 500 mug g(-1) when 4g of sample is extracted. Recovery assays done with standard betaine hydrochloride and hard red wheat resulted in a consistent recovery of 80%. Betaine content was quantified in several feed ingredients, including alfalfa (1.77 mg kg(-1)), wheat (3.96 mg kg(-1)), wheat middlings (4.98 mg kg(-1)) and poultry meal (0.77 mg kg(-1)). Betaine in corn and soybean meal was not detectable by this method, even when 16g of sample was used (<125 mg kg(-1)). Betaine present in several feed ingredients should influence choline supplementation to animal feeds and may have implications for human health. (C) 2002 Society of Chemical Industry.

Effects of extraction methods on yam (Dioscorea alata) starch characteristics

Starch extraction from roots and tubers uses grating with water and sieves to separate the starch slurry from residual mass. The starch is recovered by decantation or centrifugation. The yam starch extraction is difficult due to high viscosity of the slurry caused by non-starch polysaccharides (NSP). The establishment of an efficient extraction process may turn yam into a competitive raw material. In this paper Dioscorea alata starch extracted by four methods was characterized in order to establish the impact of treatments. When the tubers were digested with an aqueous oxalic acid/ammonium oxalate (OA/AO) 1/1 solution, it was easier to separate the starch slurry from residual mass, because viscosity was reduced. For all the others methods tested, the viscosity remained almost the same. The nitrogen present in yam tubers was removed during the different extractions to a different extent. The largest nitrogen reduction was observed with ONAO followed by the control (water). The spectrum of starch granules sizes obtained also varied according to the treatment. Results proved that NSP carries small starch granules over to the waste water. The smaller starch granules diameter varied from 1.9 mu m (OA/AO extraction) to 13.5 mu m (water and pectinase extractions). The larger diameter varied from 41.0 mu m (NaOH treatment) to 67.7 mu m (ONAO). All starches extracted showed a RVA behavior in agreement with literature for yam starch, but with small differences due to the influence of methods. ONAO extraction showed the best recovery (18 g of starch/100 g tuber yam) and granular variation but it interfered with the rheological behavior of starch.

Effect of intraluminal distention on microvascular perfusion in the equine small colon

Objective-To determine the effect of experimental intraluminal distention on microvascular perfusion of the small colon in horses.Animals-6 mixed-breed healthy horses (mean age [+/- SD], 9.1 +/- 2 years).Procedure-Under general anesthesia, the small colon was exposed by celiotomy and 3 segments were demarcated. In 1 of these segments, intraluminal obstruction was created by placement of a latex balloon inflated to a pressure of 40 mm Hg (obstructed segment). The other segments were the sham-operated segment and the control segment. Microvascular perfusion was evaluated in the mucosal, submucosal, muscular, and serosal layers by injection of 15-mum-diameter colored microspheres into branches of the caudal mesenteric artery. Recovery of microspheres was performed by tissue digestion, washing, and centrifugation. Distribution of microspheres in the intestinal layers was evaluated by direct observation of stained frozen sections by light microscopy.Results-A significant reduction was observed in total microvascular perfusion of obstructed segments, which was 26.4% of that of control segments. This reduction was not evident in the mucosal layer.Conclusions and Clinical Relevance-Intraluminal distention of the equine small colon wall can promote ischemia by a reduction in microvascular perfusion in the intestinal wall. Intestinal layers do not seem to be affected to the same extent, because the absolute value for mucosal perfusion did not decrease in the obstructed segment.

Laserlike emission from silica inverse opals infiltrated with rhodamine 6G

Monodisperse latex spheres were obtained by a surfactant free styrene polymerization method and used to obtain colloidal crystals by controlled centrifugation settling. Silica inverse opals were then prepared by using the colloidal crystals as templates and TEOS/ethanol solution. The inverse opals were infiltrated with Rhodamine 6G and laserlike emission was observed at 590 nm under 532 nm pump wavelength. The data show line narrowing of the dye fluorescence and a laser threshold of similar to 0.1 mJ/pulse. Local-field effects and light scattering due to structural defects are the main mechanisms contributing to generation of the laser-action observed. (c) 2005 Elsevier B.V. All rights reserved.

Rare earth doped synthetic opals and inverse opals

Monodisperse spheres of silica and latex were obtained by a surfactant free styrene polimerization and the Stober method respectively. Controlling settling either by centrifugation or by dip-coating colloidal crystals could be obtained. Silica inverse opals were prepared by using the latex colloidal crystals as templates and TEOS/ethanol solution. Eu3+ containing silica spheres were obtained dispersing silica spheres in Eu(NO3)(3) isopropanol solutions. Emission spectra suggest the formation of an amorphous Eu3+ containing phase well adhered at the spheres surface. The utilization of solutions of trifluoroacetates salts of Pb2+ and Eu3+ was observed to destroy the silica spherical pattern when samples are treated at 1000degreesC. In that case nanocrystals of PbF2 and amorphous silica were obtained after heat treatment.

An HPLC-PAD method to analyse flavonoid glycosides and styrylpyrones from Cryptocarya species (Lauraceae)

An HPLC-PAD method has been developed in order to evaluate simultaneously the main secondary metabolites, flavonoid glycosides and styrylpyrones, of leaves of Cryptocarya moschata. The sample preparation, consisting of extraction, liquid-liquid extraction and centrifugation, requires minimum sample manipulation but produces high yields with reproducibility, selectivity and simplicity. HPLC on a C, column presents each class of metabolites grouped and with good resolution of the main compounds. The experimental conditions can be used to study inter- and intra-specific variability of secondary metabolites in Cryptocarya spp. Copyright (c) 2005 John Wiley A Sons, Ltd.

Effects of self-assembly process of latex spheres on the final topology of macroporous silica

This paper surveys the topology of macroporous silica prepared using latex templates covering the submicrometric range (0.1-0.7 mu m). The behavior of latex spheres in aqueous dispersion has been analyzed by dynamic light scattering (DLS) measurement indicating the most appropriate conditions to form well-defined cubic arrays. The optical behavior of latex spheres has been analyzed by transmittance and reflectance measurements in order to determine their diameter and filling factor when they were assembled in bidimensional arrays. Macroscopic templates have been obtained by a centrifugation process and their crystalline ordering has been confirmed by porosimetry and scanning electron microscopy. These self-assembled structures have been used to produce macroporous silica, whose final topology depends on the pore size distribution of the original template. It has been seen that latex spheres are ordered in a predominant fcc arrangement with slipping of tetragonal pores due to the action of attractive electrostatic interactions. The main effect is to change the spherical shape of voids in macroporous silica into a hexagonal configuration with possible applications to fabricate photonic devices with novel optical properties. (c) 2005 Elsevier B.V. All rights reserved.

Acid Black 48 dye biosorption using Saccharomyces cerevisiae immobilized with treated sugarcane bagasse

The textile industry consumes large quantities of water and chemicals, especially in dyeing and finishing processes. Textile dye adsorption can be accomplished with natural or synthetic compounds. Cell immobilization using biomaterials allows the reduction of toxicity and mechanical resistance and opens spaces within the matrix for cell growth. The use of natural materials, such as sugarcane bagasse, is promising due to the low costs involved. The aim of the present study was to evaluate the use of sugarcane bagasse treated with either polyethyleneimine (PEI), NaOH or distilled water in the cell immobilization of Saccharomyces cerevisiae for textile dye removal. Three different adsorption tests were conducted: treated sugarcane bagasse alone, free yeast cells and bagasse-immobilized yeast cells. Yeast immobilization was 31.34% with PEI-treated bagasse, 8.56% with distilled water and 22.54% with NaOH. PEI-treated bagasse exhibited the best removal rates of the dye at all pH values studied (2.50, 4.50 and 6.50). The best Acid Black 48 adsorption rates were obtained with use of free yeast cells. At pH 2.50, 1 mg of free yeast cells was able to remove 5488.49 g of the dye. The lowest adsorption capacity rates were obtained using treated bagasse alone. However, the use of bagasse-immobilized cells increased adsorption efficiency from 20 to 40%. The use of immobilized cells in textile dye removal is very attractive due to adsorbed dye precipitation, which eliminates the industrial need for centrifugation processes. Dye adsorption using only yeast cells or sugarcane bagasse requires separation methods.

An alternative methodology for the extraction of humic substances from organic soils

The present study reports on an alternative methodology for the extraction of Humic Substances (HS) from the soil. The extractions were carried out with 0.5 M KOH for 3 h, at a ratio of 1:20 (m/v) under a nitrogen atmosphere. The HS were separated by centrifugation based on their solubility in alcaline solution. This methodology was compared with the usual procedure in three different soil samples and in one sample from vermicompost. The yield, E4/E6 ratio, ash content, and the elemental composition (C, H, O, N) of the extracted HS have been determined. The functional groups were identified by Fourier-transform infrared spectroscopy. This novel procedure adds a new perspective to the extraction of humic substances due to the short time and high performance of the extraction in relation to the usual procedure.