RESUMEN
The electrical Ca test was used to measure H2O vapor transmission through polyethylene naphthalate (PEN) polymer with a thickness of 200 µm. On the basis of the time required for the normalized conductance of the Ca film to reach zero, the H2O vapor transmission rate was determined versus H2O flux, temperature, and saturation of the PEN polymer with H2O. The H2O vapor transmission rate was proportional to the H2O flux and only weakly dependent on temperature at constant H2O flux. The transmission coefficient, Γ, for H2O through the PEN polymer at 70 °C was Γ â¼ 3.2 × 10(-10). The corresponding water vapor transmission rate (WVTR) at 70 °C/80% RH was 0.65 g/(m(2) day). The temperature dependence of the H2O vapor transmission rate through PEN at constant H2O flux yielded an activation barrier of E = 12.4 kJ/mol. There was no observable reservoir effect for H2O in the PEN polymer. The H2O vapor transmission rates for initially dry or H2O-saturated PEN polymer substrates were nearly identical at various temperatures. Although the time required for the normalized conductance of the Ca film to reach zero was inversely proportional to the H2O flux, the Ca film conductance did not decrease linearly versus H2O exposure. The Ca film conductance changed very little during initial H2O exposure. This behavior may be caused by the nonlinear oxidation kinetics of the Ca film.
RESUMEN
A recent survey of foods that constitute the major sources of vitamin C in the American diet yielded information on the total content of this vitamin as well as the amount of its two forms, ascorbic acid and dehydroascorbic acid (DHAA) in these foods. Samples of individual foods showed a surprising large range of vitamin content even for foods collected from the same regions of the country and from the same source. The amount of DHAA in the different foods varied from approximately 10% to 20% of the total vitamin content. The large range of values for the vitamin content in a given food suggests further that in human-diet studies, when the major sources of vitamin C are from a few foods, daily analyses are required for the necessary precision.
Asunto(s)
Ácido Ascórbico/análisis , Análisis de los Alimentos , Cromatografía/instrumentación , Cromatografía/métodos , Análisis de los Alimentos/métodosRESUMEN
Although testicular cancer accounts for only one percent of all male malignancies, it affects a predominantly young population (15-35 years). Despite its relatively low incidence, the emotional, financial, and psychosocial implications of the disease and its treatment in this young population are enormous. Knowledge of the disease and its treatment-related side effects and toxicities is essential to planning comprehensive nursing care. This article reviews the natural history, treatment, and nursing management of the client with testicular cancer, focusing on the specific and most current issues associated with this disease and its chemotherapeutic treatment. Application of research findings in the management of both short- and long-term sequelae are discussed.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Testiculares/enfermería , Antieméticos/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Humanos , Masculino , Náusea/tratamiento farmacológico , Náusea/enfermería , Estadificación de Neoplasias , Neoplasias Testiculares/tratamiento farmacológico , Neoplasias Testiculares/patología , Vómitos/tratamiento farmacológico , Vómitos/enfermeríaRESUMEN
Laboratory robotic technology has made it possible to automate the manually intensive operations associated with the extraction of vitamins from food. The modular approach to robotics allows the conversion from one extraction procedure to another by a simple addition or replacement of a module plus reprogramming. This is illustrated for the extraction of vitamins C and B1 from food samples. Because many of the organic micronutrients are unstable, storage and extraction conditions must be established to stabilize labile compounds if the full capabilities of robotics are to be realized.
Asunto(s)
Análisis de los Alimentos/métodos , Vitaminas/análisis , Animales , Pollos , Cromatografía Líquida de Alta Presión/métodos , Análisis de los Alimentos/instrumentación , Carne/análisis , Robótica/instrumentaciónRESUMEN
A high performance liquid chromatographic (HPLC) procedure has been developed for the analysis of ascorbic acid and dehydroascorbic acid in complex matrices. Separation is accomplished with an anion-exchange resin and fluorescent detection is achieved through post-column inline chemistry, involving oxidation of ascorbic acid to dehydroascorbic acid followed by reaction with o-phenylenediamine to form a fluorescent product. Lower limits of detection for both forms of vitamin C are well below the levels found in the usual food sources of this vitamin. The extraction procedures developed yield clean samples for analysis with minimal loss of the vitamers during the analytical procedures. Recoveries are in the range of 90-107%. The results obtained with this HPLC procedure agree well with those obtained with a modified version of the classical procedure of Deutsch and Weeks. A variety of foods including fruit juices, vegetables, and fruits were analyzed.
Asunto(s)
Ácido Ascórbico/análisis , Análisis de los Alimentos , Bebidas/análisis , Cromatografía Líquida de Alta Presión/métodos , Citrus/análisis , Ácido Deshidroascórbico/análisis , Frutas/análisis , Espectrometría de Fluorescencia/métodosRESUMEN
Simple expressions are given for the dispersion and the travel times of samples in simple flow-injection analysis systems. The sum of these two quantities is the total residence time of the sample in the system. The expressions are based on numerical solutions of the diffusion-convection equation. Preliminary experiments are in agreement with the derived simple expressions, as are peak curve shapes. Diffusion coefficients can be obtained in a straightforward manner.
RESUMEN
Weanling male rats were fed either a vitamin E-deficient Torula yeast diet or the same diet supplemented with 100 ppm vitamin E for a period of 3 months. One group of animals fed each diet received 250 ppm lead in the drinking water, whereas another group of animals fed each diet received no lead in the water. Vitamin E deficiency per se had little or no effect on hematocrit value, reticulocyte count, spleen weight, or erythrocyte mechanical fragility in rats not poisoned with lead. On the other hand, the decreased hematocrit, increased reticulocyte count, and splenic enlargement due to lead poisoning were much more pronounced in vitamin E-deficient rats than in rats supplemented with vitamin E. The resistance to mechanical trauma of red blood cells from vitamin E-deficient lead-poisoned rats was much less than that of red cells from vitamin E-adequate lead-poisoned rats. Dietary vitamin E status had no significant influence on the increased mechanical fragility of erythrocytes from nonpoisoned rats caused by exposure to lead in vitro. These results suggest that vitamin E deficiency enhances the susceptibility of animals to the in vivo hemolytic effect of lead poisoning.