Calibration Curves of Culture Density Assessed by Spectrophotometer for Three Microalgae (Nephroselmis sp., Amphidinium carterae and Phormidium sp.)

This study concerns the finding of an effective operational equation relating the measured absorpbance (or O.D. - optical density) in a spectrophotometer of the suspended cells of microalgae to their cell density (c.d.) in culture in order to construct calibration curves for use in culture operations. The microalgae examined were the chlorophyte Nephroselmis sp., the dinophyte Amphidinium carterae and the filamentous cyanobacterium Phormidium sp. Wavelengths of 430 and 680 nm were selected that correspond to chlorophyll-a peaks of their absorption spectra were used and additionally 750 and 570 nm where absorbance was not peaked. From all equations extracted best fitness with strong predictive values were those of a logarithmic type: O.D.=0,9328*ln(c.d.)-14,108 (R2=0,9943) at 680 nm for Nephroselmis, a power equation: O.D.=0,0000009*(c.d.)0,9195 (R2=0,9936) at 680 nm for Amphidinium and a polynomial second order: O.D.=0,9869(c.d.)2+2,4393(c.d.)+0,2666 (R2=0,9737) at 570 nm for Phormidium.

Ecuación modelo operacional con aplicación de balance de materia en estado no estacionario.// Operational model equation applying material balance in a non-stationary state.

La investigación tuvo como objetivo principal determinar la ecuación modelo operacional aplicando el principio de balance de materia en estado no estacionario. Para la representación del proceso se utilizó un tanque con agua el cual simulada el caudal de entrada al tanque que contenía una solución concentrada de 33° Brix, y de este se desprendía un caudal de salida a un tercer tanque. Las muestras se recolectaron del caudal de salida del segundo tanque en un rango de tiempo de 30 segundos, obteniendo un total de 20 muestras, luego se evaluó su concentración en °Brix analizando en el laboratorio. En la parte operacional se aplica un balance de materia en estado estacionario donde se determinó la ecuación modelo donde al aplicar el tiempo en el cual se recolecto la muestra se determinaba su concentración en °Brix. Se analizó los datos arrojados por análisis de laboratorio y los obtenidos por aplicación de la ecuación modelo en el programa estadístico Statgraphics Centurion XVI.I, el cual determino que no existió diferencia significativa entre cada uno de los datos estudiados. La ecuación modelo establecida para determinación de la concentración de una sustancia resulto útil en al investigación y para su aplicación en futuros estudios. AbstractThe aim of the present research work was to determine mathematical model of the operational equation applying non-stationary state material balance principle. A tank filled with water was used for the representation of the mechanical process, which simulated an input flow to a tank containing a 33° Brix sucrose concentrated solution, from where an output flow to a third tank was released. The samples were collected from the second tank output flow in time ranges of thirty seconds; a total number of twenty samples were obtained. For each sample, concentration in means of °Brix, was registered in laboratory facilities. In the operational part of the present research, a material balance in non-stationary state was utilized. The model equation for the previously mentioned state, where applying time when a sample was collected and its concentration by means of °Brix, was determined. Obtained data from laboratory analysis and from the model equation application were analyzed with statistical package Statgraphics Centurion XVI.I version XVI 16.1.18. For each data set compared, no significant differences were found. The established model equation for the determination of the concentration of a substance was useful in this investigation and it can be used in further research works.

PERSAMAAN OPERASIONAL DALAM PROSES LAMINASI BAHAN KEMASAN

Plastick sheet coated like paper for food, bag packaged plastic, etc now is needed for industry. To find material it laminated, it form still in coated laminated process with plastic film. An operational equation in the laminated process need to be founded so that its laminated process can be adjusted with the assigned order. That is usually problem that is not be solved by producers. By using mass balanced principles, the equation can be founded. By using data collected, we can calculate constanta of the equation and also RPM display value that will be used to determine thick of coated film needed for the width film as ordered.

Rates of glucose utilization in brain of active and hibernating ground squirrels

Rates of glucose utilization (CMRGlc) were determined in some cerebral structures of active warm- and cold-adapted ground squirrels and hibernating ground squirrels with [14C]deoxyglucose (DG) by direct chemical measurement of precursor and products in samples dissected from funnel-frozen brain. The rate of supply relative to demand of glucose and [14C]DG in brain of hibernating animals was similar to or greater than that of controls. [14C]DG cleared from the plasma in hibernators much more slowly than in active animals, and the level of unmetabolized [14C]DG in brain and the integrated specific activity of the precursor pool in plasma exceeded those of the active animals by 4- to 10-fold. At 45 min after an intravenous pulse of [14C]DG, the unmetabolized [14C]DG remaining in the brains of the hibernators accounted for approximately 96% of the total 14C compared with approximately 10-15% in the active animals. The value of lambda, a factor contained in the lumped constant of the operational equation of the [14C]DG method, was estimated for each animal and found to be relatively constant over the sixfold range of glucose levels in the brains of all animals. Calculated CMRGlc in squirrels in deep hibernation was only 1-2% of the values in active animals.

The Influence of Biological and Technical Factors on the Variability of Global and Regional Brain Metabolism of 2-[18F]Fluoro-2-Deoxy-D-Glucose

This study investigated the influence of biological and technical factors on variations of global and regional cerebral metabolic rate of glucose (CMRglc) measured with 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG). Twelve male volunteers (22–40 years) were investigated on three or four occasions for a total of 42 studies. We calculated the variance/covariance of the following parameters: CMRglc, six parameters of the blood clearance of [18F]FDG, hour of injection, peak time of blood radioactivity, and six components of the operational equation (nonradioactive blood glucose concentration, brain radioactivity, two integrals, numerator, and denominator). There was correlation among these six components, except for nonradioactive blood glucose. However, the correlation between the CMRglc and the individual components of the operational equation was poor. The inter- and intrapersonal CMRglc coefficients of variations were 13.8 and 7.1%, respectively. In contrast, coefficients of variations of the numerator and denominator of the operational equation were 34.6 and 32.6%, respectively, and were always in the same direction. No correlation was found between CMRglc and the technical factors in the numerator and denominator of the operational equation. Factor analysis disclosed that a single factor was responsible for 70% of the variance. This factor included caudate, putamen, thalamus, frontal cortex, temporal cortex, and cingulate gyrus. These structures are involved with multiple complex functions, from autonomic motor control to behavior and emotions. The intrinsic metabolic variability of these structures, along with the basal metabolic processes that are continuously going on in the brain, may be the best explanation for the variance encountered in our investigation.

Effects of Focal Cortical Freezing Lesion on Regional Energy Metabolism

Freezing lesions have been shown to cause a depression in glucose use, particularly in cortical areas of the brain ipsilateral to the lesion, and this effect was interpreted to be caused by a depressed functional activity in these regions. The metabolic status of the affected areas has not been previously examined and could be a factor in the observed changes in local CMRglc. In frozen-cut and dried sections taken from brains 3 days after freeze lesioning, discrete pieces of the median and lateral parietal cortex, striatum, hippocampus, and hypothalamus were dissected and analyzed for ATP, P-creatine, glucose, and lactate. CMRglc measurements were also made in the same animals. The concentrations of the four metabolites were significantly increased in the lesioned hemisphere, with the most predominant effects observed in the cortical areas that exhibited the greatest depression in CMRglc. The enriched metabolite profile, particularly in the cortical areas, is consistent with the hypothesis that decreased glucose use in the traumatized brain is caused by diminished need rather than by decreased supply of energy. Because the lumped constant in the operational equation of the deoxyglucose method for determination of CMRglc is a function of brain glucose content and decreases gradually in hyperglycemia, the degree of metabolic depression in cortical areas of lesioned hemisphere probably have been somewhat overestimated in this and previous publications. However, provisionally recalculated local CMRglc in the lesioned hemisphere remain significantly lower than in the contralateral hemisphere and in the normal brain.

Direct Chemical Measurement of the λ of the Lumped Constant of the [14C]Deoxyglucose Method in Rat Brain: Effects of Arterial Plasma Glucose Level on the Distribution Spaces of [14C]Deoxyglucose and Glucose and on λ

The lumped constant in the operational equation of the 2-[14C]deoxyglucose (DG) method contains the factor λ that represents the ratio of the steady-state tissue distribution spaces for [14C]DG and glucose. The lumped constant has been shown to vary with arterial plasma glucose concentration. Predictions based mainly on theoretical grounds have suggested that disproportionate changes in the distribution spaces for [14C]DG and glucose and in the value of λ are responsible for these variations in the lumped constant. The influence of arterial plasma glucose concentration on the distribution spaces for DG and glucose and on λ were, therefore, determined in the present studies by direct chemical measurements. The brain was maintained in steady states of delivery and metabolism of DG and glucose by programmed intravenous infusions of both hexoses designed to produce and maintain constant arterial concentrations. Hexose concentrations were assayed in acid extracts of arterial plasma and freeze-blown brain. Graded hyperglycemia up to 28 m M produced progressive decreases in the distribution spaces of both hexoses from their normoglycemic values (e.g., ∼ – 20% for glucose and – 50% for DG at 28 m M). In contrast, graded hypoglycemia progressively reduced the distribution space for glucose and increased the space for [14C]DG. The values for λ were comparatively stable in normoglycemic and hyperglycemic conditions but rose sharply (e.g., as much as 9–10-fold at 2 m M) in severe hypoglycemia.

Measurement of regional gastroduodenal blood flow with iodo [14C]antipyrine autoradiography

Regional blood flow was measured in the gastroduodenal area by means of iodo[14C]antipyrine autoradiography. The tracer was given intravenously over a short period of time in awake rats followed by cardiac arrest and quick freezing of stomach and duodenum. Dry autoradiography of frozen sections provide a pictorial representation of radioactivity in the different tissue layers. This could be converted to blood flow after incorporation of the time course of blood radioactivity into an operational equation. A high level of resolution was achieved, allowing delineation of blood flow compartments of small dimensions such as single villi and regions within the fundic mucosa. The value of blood flow recorded in resting conditions were in agreement with previous observations with the microspheres technique. Hypotension induced a generalized decrease in blood flow, most marked in the corpus mucosa.