Search results for "Laboratory flask"
showing 9 items of 9 documents
Assessment of allyl isothiocyanate as a fumigant to avoid mycotoxin production during corn storage
2016
The occurrence of fungi and mycotoxins in foods modify sensorial properties and represents a health risk for consumers, and the use of natural antimicrobials may be an alternative to reduce this problem. The objective of this study was evaluate the potential of allyl isothiocyanate (AITC) in inhibit the production of mycotoxins in corn kernels by Aspergillus parasticus, Fusarium tricinctum, Fusarium verticillioides, Alternaria alternata and Gibberela zeae. Kernels were treated with gaseous AITC at 50, 100 or 500 μL/L during 48 h in hermetic flasks. Then, flasks were opened for 24 h and 100 g of corn were inoculated with 105 conidia/g of either fungal species. Flasks were kept at 23 °…
Semiautomatic growth analysis of multicellular tumor spheroids.
2011
Multicellular tumor spheroids (MCTS) are routinely employed as three-dimensional in vitro models to study tumor biology. Cultivation of MCTS in spinner flasks provides better growing conditions, especially with regard to the availability of nutrients and oxygen, when compared with microtiter plates. The main endpoint of drug response experiments is spheroid size. It is common practice to analyze spheroid size manually with a microscope and an ocular micrometer. This requires removal of some spheroids from the flask, which entails major limitations such as loss of MCTS and the risk of contamination. With this new approach, the authors present an efficient and highly reproducible method to an…
An Optimized and Rapid DNA Extraction Method From Leaves of Grapevine Suitable for PCR-DGGE Based Analysis
2010
Molecular techniques and genetic studies require a fair amount of DNA of high quality in order to produce reliable and clear results (Li et al., 2007). In grapevine, the yield and quality of DNA can be significantly affected by secondary metabolites such as polyphenols, polysaccharides and tannins, that may be consistently abundant during the different stages of leaf development (Iandolino et al., 2004). The development of a simple, rapid and reliable method for the extraction of genomic DNA from grape leaves collected at several stages during development, as well as from healthy grape leaves and leaves infected by pathogenic microorganisms, was the main objective of this study. The protoco…
Calibration of misonidazole labeling by simultaneous measurement of oxygen tension and labeling density in multicellular spheroids
1995
To correlate misonidazole concentrations and oxygen pressures (Po2) at identical locations within EMT6/Ro multi-cell spheroids (mean diameters +/- SD: 867 +/- 20 microns), Po2 measurements were performed with oxygen-sensitive microelectrodes during incubation of these spheroids with tritiated misonidazole (10 mg/I; 445 microCi/mg). In each individual spheroid, Po2 profiles were correlated with the corresponding spatial distribution of misonidazole as quantified by conventional autoradiography and grain counting. To compare the oxygenation status of spheroids in the measuring chamber with that of spheroids in spinner culture, misonidazole labeling was performed in both environments following…
Influence of the concentration of oxygen on the swimming path of Brachionus plicatilis (Rotifera)
1993
Brachionus plicatilis females were maintained for > 24 hours in water where the concentration of oxygen was precisely controlled (spherical flasks with ≥ 6 mg 1−1 or < 0.5 mg 1−1; food = dead Tetraselmis sp.). Each female was randomly taken from one flask and quickly placed in an observation chamber containing the same experimental conditions. The swimming path was videotaped (5 minutes); then the size of the female was measured. The tape was analyzed by automatic tracking (25 x, y coordinates of the center of the animal, in a 512 × 512 pixels space). The swimming path was analyzed for ~45 females in both treatments. The speed (mm s−1 body length−1) was calculated for all trajectories, or o…
Microelectrode Measurements of Oxygen Tension Distributions in Multicellular Spheroids Cultured in Spinner Flasks
1984
Since multicellular spheroids were introduced into cancer research by Sutherland et al. (1970, 1971), they have been widely used for studying the susceptibility of cancer cells to various treatment modalities. Many of these investigations provided evidence for a major role of oxygen in controlling the metabolic and cell cycle state of the tumor cells, thus modifying the responsiveness of the cells to therapy. Several investigators have measured O2 tension (PO2) distributions in spheroids with O2-sensitive microelectrodes (Carlsson et al. 1979; Kaufman et al. 1981; Mueller-Klieser and Sutherland 1982a, b, 1983; Mueller-Klieser et al. 1983). The measurements produced PO2 values that varied co…
Study of two MTA cements
2014
Introduction: To determine and compare the pH, conductivity and calcium release of an experimental Portland cement (PE) consisting of trioxid mineral aggregate and a comercially available modified Portland cement (C.P.M.) after 1, 2, 3, 4, 8, 10, 15 and 30 days. Material and Methods: Cements were mixed following the manufacturer's instructions, with a powder: liquid ratio of 3:1. Each cement was placed in 12 PVC tubes 1 mm in diameter and 10 mm in length and allowed to set. Four empty tubes were used as negative controls. Tubes were submerged in plastic flasks containing 10 ml deionized water and stored at 37ºC and 100% humidity. After 1, 2, 3, 4, 8, 10, 15 and 30 days tubes were removed fr…
Microfungal Alkylation and Volatilization of Selenium Adsorbed by Goethite
2009
Selenium adsorbed in the oxyanionic form by Fe-oxides like goethite is considered of benefit for long-term stabilization of (79)Se under near field conditions of radionuclide waste disposal sites. However, microbe-mediated volatilization of the uranium fission product (79)Se has not yet been considered for risk assessment based on the use of the water-solid distribution coefficient K(D). We have performed incubation experiments in a ternary system selenium-microbe-goethite and show that mycobiota including the common black microfungi genera Alternaria alternata are capable of volatilizing the Se even if immobilized by goethite. The microfungi were incubated in a standardized nutrient broth …
A laboratory experiment on inferring Poiseuille's law for undergraduate students
2006
In this paper a laboratory experiment is proposed to infer Poiseuille's law. A simple set-up based on two flasks joined by a detachable tube allows one to measure using tubes of different radii and different lengths. One of the flasks is connected to a vacuum pump to control the pressure differential between the tube extremes. The influence on the flow of different radii, lengths, pressures and viscosities can be studied in a didactic way by measuring the flow rate for each of these variables. The experiment can be performed getting together the students in groups, so that each group concentrates on the effect on the flow of a specific variable, leaving the rest fixed. After putting togethe…