Monte Carlo simulation of parameter confidence intervals for non-linear regression analysis of biological data using Microsoft Excel.

This study describes a method to obtain parameter confidence intervals from the fitting of non-linear functions to experimental data, using the SOLVER and Analysis ToolPaK Add-In of the Microsoft Excel spreadsheet. Previously we have shown that Excel can fit complex multiple functions to biological data, obtaining values equivalent to those returned by more specialized statistical or mathematical software. However, a disadvantage of using the Excel method was the inability to return confidence intervals for the computed parameters or the correlations between them. Using a simple Monte-Carlo procedure within the Excel spreadsheet (without recourse to programming), SOLVER can provide parameter estimates (up to 200 at a time) for multiple 'virtual' data sets, from which the required confidence intervals and correlation coefficients can be obtained. The general utility of the method is exemplified by applying it to the analysis of the growth of Listeria monocytogenes, the growth inhibition of Pseudomonas aeruginosa by chlorhexidine and the further analysis of the electrophysiological data from the compound action potential of the rodent optic nerve

Regression Analysis to Determine the Reserve Strength Ratio of Fixed Offshore Structures

This study estimates the Reserve Strength Ratio (RSR) of fixed offshore structures with the utilization of regression analysis, which is capable in replacing the conventional expensive and time consuming methods currently adapted in the oil and gas industry. Offshore structures from the three regions of Malaysian Waters namely Peninsular Malaysia, Sarawak and Sabah were used to perform the analysis of different jacket configurations and sea-states accordingly. The pushover analysis of this study was performed by SACS program version 5.3 and the regression analysis was done using Microsoft Excel. Finding has revealed that regression analysis is able to produce regression coefficients to formulate non-linear regression equations fitting to the set of data to estimate the platform RSR

Regression Analysis to Determine the Reserve Strength Ratio of Fixed Offshore Structures

This study estimates the Reserve Strength Ratio (RSR) of fixed offshore structures with the utilization of regression analysis, which is capable in replacing the conventional expensive and time consuming methods currently adapted in the oil and gas industry. Offshore structures from the three regions of Malaysian Waters namely Peninsular Malaysia, Sarawak and Sabah were used to perform the analysis of different jacket configurations and sea-states accordingly. The pushover analysis of this study was performed by SACS program version 5.3 and the regression analysis was done using Microsoft Excel. Finding has revealed that regression analysis is able to produce regression coefficients to formulate non-linear regression equations fitting to the set of data to estimate the platform RSR

Caracterización termodinámica de mezclas acuosas de aminas

El importante crecimiento económico en nuestra sociedad desde mediados del siglo pasado ha estado asociado a un notable aumento del consumo energético, basado en un modelo energético centrado en el uso de combustibles fósiles , lo que ha conllevado un aumento de las emisiones de gases de efecto invernadero. La problemática generada como consecuencia del aumento del CO2, principal gas causante del efecto invernadero, ha obligado a tomar iniciativas que traten de reducir o evitar que el CO2 de las emisiones, principalmente de la industria alcance la atmósfera. Los sistemas de absorción química basados en disoluciones acuosas de aminas han sido utilizados durante años, especialmente para la eliminación de gases ácidos del gas natural. En la captura de CO2 pueden utilizarse aminas primarias, secundarias y terciarias, y cada una tiene sus ventajas y desventajas. Propiedades como la densidad, viscosidad y capacidad calorífica de dichas mezclas intervienen por ejemplo, en el modelado de la tasa de transferencia de masa, dimensionamiento de tuberías y el diseño de bombas e intercambiadores de calor. Es por esta razón que conocer dichas propiedades termofísicas es de vital importancia para que el proceso de captura sea llevado de forma eficiente. Conscientes de esta problemática el Grupo de Investigación de Excelencia TERMOCAL (Laboratorio de Metrología y Calibración de la Universidad de Valladolid) y con la financiación de la Junta de Castilla y León desarrollan el proyecto: Biogás renovable y procesos de captura del CO2 de combustión asociados como base a la sostenibilidad energética ambiental: Investigación Termodinámica Experimental. Dicho proyecto en el cual se enmarca este trabajo tiene entre las sus líneas de desarrollo la investigación de propiedades termodinámicas de las aminas involucradas en el proceso de captura de CO2 proveniente de gases de postcombustión.Departamento de Ingeniería Energética y FluidomecánicaDoctorado en Investigación en Ingeniería Termodinámica de Fluido

The Effect of Solids Residence Time on Phosphorus Uptake in Co-precipitation Systems Targeting Low Phosphorus Concentrations

Chemical phosphorus (P) removal is generally considered to be necessary when attempting to achieve ultra low P concentrations (i.e. < 50 μg/L) in wastewater treatment. However, the impact of aging of chemical solids (i.e. hydrous ferric oxides (HFO)) and thereby solids residence times (SRT) typical of conventional wastewater treatment processes on P removal is not well understood. This study characterized the uptake of P in co-precipitation systems under varying influent P concentrations and methods of P addition (i.e. steady state versus transient dosing); identified the impact of SRT on P removal, HFO floc structure, equilibrium adsorption of P to HFO and on the dynamics of P removal under steady state and transient conditions; and described the dynamic behaviour of P sorption onto HFO floc by the development of a model. The study employed lab scale continuous flow sequencing batch reactor (SBR) pilots that received the discharge of a flash mix tank. The pilots were fed with a synthetic natural water and operated over a range of SRTs (i.e. 2.8-26.6 days). Operation at different influent P concentrations and methods of P addition (i.e. steady state vs. transient dosing) was evaluated. Batch sorption testing with solids from the SBRs was also conducted. Under steady state operating conditions the majority of P removal occurred in the flash tank (94% with 3.4 mg influent P/L; 83% with 6.4 mg influent P/L) with an additional smaller fraction of removal in the SBRs (additional 3.3 – 4.8% removal with 3.4 mg influent P/L; 5.5 - 8.8% with 6.4 mg influent P/L). Soluble P uptake was higher at SRTs ≤ 7.4 days with 3.4 mg influent P/L and SRTs ≤ 14.3 days with 6.4 mg influent P/L. The floc morphology (i.e. open vs. compact floc structure) in the flash solids was found to be different from that of the SBR aged solids using SEM analysis. Particle size distributions were found to be the same in all systems supporting the hypothesis that changes in floc morphology were more responsible for differences in P removal than floc size. Batch sorption studies indicated that fresh HFO had a higher sorption capacity in comparison to aged (2.8, 7.4, 10.8 and 22.8 day) HFO. P desorption from HFO solids was found to be negligible supporting chemisorption as the mechanism of P adsorption. P adsorption onto HFO solids was determined to be best described by the Freundlich isotherm. An equilibrium model was found to adequately describe P adsorption onto HFO solids of different ages. Modelling showed that fresh HFO contributed more to P sorption than aged HFO in each SBR implying that the fresh flash solids were more responsible for the observed P uptake in the SBRs in comparison to the aged SBR solids. Transient studies showed that P removal in the SBRs and batch sorption tests was characterized by an initial fast period of removal followed by a period of slower removal until pseudo-equilibrium was reached. A model was developed to describe the dynamic behaviour of P sorption onto three different solid types (i.e. steady state dosed SBR solids, transient dosed SBR solids, and preformed batch solids). Overall, the calibrated model was found to provide a good description of P removal in the SBRs and batch testing. The model was able to reflect the different process conditions (i.e. mixing) in experiments conducted in the SBRs and the batch tests. This was reflected in the estimated values of the rate coefficients obtained from the batch tests and the SBRs. It was found that the same rate coefficient could be used to describe P adsorption onto HFO floc of different ages (i.e. 2.8-26.6 days)

Modelamiento del proceso de extracción de colágeno a partir de subproductos piscícolas mediante el uso de membranas de filtración a flujo cruzado

RESUMEN:En este trabajo se estudió el proceso de extracción de colágeno a partir de tres subproductos de pescado: escamas de tilapia roja (ETR), espina dorsal de trucha (EDT) y piel de tilapia nilótica (PTN). En general, el proceso consistió en 4 etapas: desengrasado, pretratamiento alcalino, extracción ácida y filtración tangencial. Para seleccionar el mejor subproducto se compararon los rendimientos de extracción porcentuales de colágeno. El mejor subproducto resultó ser la PTN, con esta se estandarizó el proceso de extracción de colágeno mediante la implementación de diseños experimentales con el fin de establecer las condiciones óptimas del pretratamiento alcalino y de la extracción ácida mediante la metodología de superficie de respuesta. Adicionalmente se hizo un estudio cinético y se obtuvo un modelo fenomenológico (primera extracción alcalina) y varios empíricos (pretratamiento alcalino y extracción ácida) que mostraron una buena capacidad de predicción de los datos experimentales correspondientes a la concentración de la proteína no colagenada (PNC). Para el caso de la primera y segunda extracción alcalina fue posible construir un modelo general, basado en el modelo de segundo orden (MSO), que permitió estimar la concentración del soluto en términos de temperatura, tamaño de piel, concentración de NaOH y del tiempo. El modelo general fue ajustado para los 135 experimentos del diseño experimental de la primera extracción alcalina promediando un R2 de 0.99. Adicionalmente, se realizó un escalado del pretratamiento alcalino y de la extracción ácida desde 200 mL hasta 2 L. El extracto ácido de colágeno obtenido se concentró mediante un proceso de filtración tangencial, la cual se modeló usando mediante teoría fundamentada en los mecanismos de bloqueo de poro y formación de torta, con una capacidad de ajuste aceptable. Así mismo, se hicieron diafiltraciones con el fin de obtener un colágeno que cumpliera con los requerimientos de la norma técnica colombiana. Finalmente, el colágeno obtenido se liofilizó y se caracterizó, resultando ser tipo I, el cual tiene aplicaciones en el campo farmacéutico y alimentario.ABSTRACT: In this work the collagen extraction process was implemented from three fish by-products: red tilapia scales (RTS), trout dorsal spine (TDS) and nile tilapia skin (NTS). In general, the process consisted of four stages: defatted, alkaline pretreatment, acid extraction and cross flow filtration. In order to select the best by-product, the percentage yields of collagen extraction were compared and the NTS resulted be the best. Then collagen extraction process from NTS was standardized through the implementation of experimental designs in order to establish the optimal conditions of alkaline pretreatment and acid extraction using response surface methodology. Additionally, a kinetic study was carried out and a phenomenological model (first alkaline extraction) and three empirical models (alkaline pretreatment and acid extraction) were developed and they showed a good prediction of the experimental data of the non-collagenous protein (NCP) concentration. In the case of the first and second alkaline extraction it was possible to build a general model, based on the second order model (SOM) which allowed estimating the liquid concentration of NCP in terms of temperature, skin size, NaOH concentration and time. This model was fitted with 135 experiments of experimental design in the first alkaline extraction averaging a R2 of 0.99. Additionally, an alkaline pretreatment and acid extraction scaling up from 200 mL to 2 L was performed. The collagen acid extract obtained was concentrated by a cross flow filtration process, which was modeled using the theory of pore blocking and cake formation mechanisms, with a good prediction of the experimental data. Likewise, diafiltration were made in order to obtain a collagen that met the requirements of the Colombian technical standard. Ultimately, Freeze-dried collagen was analyzed by infrared spectroscopy, SEM and SDS-PAGE and it result be a type I collagen, which has applications in the pharmaceutical and food industry