Fast Fourier Transform

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

https://cyberleninka.org/article/n/143136.pdf

Yeasts in sustainable bioethanol production: A review.

In modeling subsurface contaminant transport, sorption is often simplified by assuming instantaneous equilibrium, isotherm linearity, and sorption‐desorption singularity. Data exhibiting behavior that deviates from that predicted by this simple model have been reported, challenging the validity of these assumptions. This nonideal sorptive behavior has been attributed to several different factors, including kinetic sorption reactions, diffusive mass transfer resistances, isotherm nonlinearity, and sorption‐desorption nonsingularity. These factors are examined and their relative impact on contaminant transport is evaluated. For hydrophobic organic compounds, physical nonequilibrium (i.e., rate‐limited mass‐transfer in aggregated or layered systems) and intraorganic matter diffusion (rate‐limited diffusion within the sorbent organic matter matrix) are probably the predominant factors causing nonideality. The relative importance of these factors is scale‐dependent. For smaller scale systems, mass‐transfer lim...

Sorption nonideality during organic contaminant transport in porous media

The growth of membrane technology

Functionality of oilseed protein products: A review

Kinetic models for the thermal cracking of Athabasca bitumen: The effect of the sand matrix

Kinetics of the thermo-oxidative and thermal cracking reactions of Athabasca bitumen

Methods of cell immobilization roughly parallel those of enzyme immobilization and can best be classified by the nature of the mode of attachment, that is, as mechanical, chemical or ionic. In mechanical immobilization, the cells are localized by means of physical barriers. In chemical immobilization, covalent bonds are formed among cells or to a solid phase. In ionic immobilization, electrostatic, van der Waal’s or London forces of attraction are present. Cells can also attach themselves to solid supports in the course of natural growth, using a combination of these means. This classification is obviously not clear-cut but does serve the purpose of organizing the diverse methods of immobilization available. In Table 2.1, examples of cell immobilization are classified by mode of attachment.

Methods of Cell Immobilization

The steady-state release of active noble gas and iodine from defective fuel elements is described either in terms of a kinetic or a diffusion model. Both models assume a diffusional release in the fuel. Transport of fission products in the fuel-to-sheath gas is represented either by a first-order rate process or diffusion process, and is characterized with an escape-rate constant or diffusion coefficient, respectively. The kinetic model predicts a release dependence on the decay constant of lambda /sup -1/2/ to lambda /sup 3/2/. The diffusion model predicts a dependence of lambda /sup -1/. Observed release data from inpile loop experiments, for a wide range of defect states, confirm the predictions of the models. A fitting of the model to the measured data yields estimates of the empirical diffusion coefficient in the fuel matrix, and the scape-rate constant or diffusion coefficient in the fuel-to-sheath gap. Evaluation of the fitted parameters enables the various rate-controlling processes to be deduced as a function of the defect size.

A Model for the Release of Radioactive Krypton, Xenon, and Iodine from Defective UO2 Fuel Elements

Flooding rates, dispersed phase hold-up, hold-up profile and drop-size distribution were investigated in rotating disc and Oldshue Rushton 0.10 m diameter, 18 compartment columns with toluene-water as the liquid-liquid system. The axial dispersed phase hold-up and the mean drop size in both contactors varied significantly with column height. The hold-up profiles were correlated by semi-theoretical models.



On a etudie les vitesses d'engorgement, la retention de la phase dispersee, le profil de retention et la distribution des dimensions des gouttes dans des colonnes a disques rotatifs et des colonnes de Oldshue et Rushton a 18 compartiments et de 0.10 m de diametre, le systeme liquide-liquide elange toluene-eau. La Retention axiale de la phase dispersee et la dimension moyenne des gouttes dans les deux contacteurs ont varie d'une maniere significative avec la hauteur de la colonne. On a etabli, au moyen de modeles semi-theoriques, des correlations pour les profils de retention.

Colin R. Phillips

Papers

Kinetic models for the thermal cracking of Athabasca bitumen: The effect of the sand matrix

Kinetics of the thermo-oxidative and thermal cracking reactions of Athabasca bitumen

Methods of Cell Immobilization

A Model for the Release of Radioactive Krypton, Xenon, and Iodine from Defective UO2 Fuel Elements

Characterization of hydrodynamic parameters in rotating disc and oldshue-rushton columns. Hydrodynamic modelling, drop size, hold-up and flooding