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Operating Parameters And Selectivity In Batch Reactive Distillation, W. Qi, M. F. Malone
Operating Parameters And Selectivity In Batch Reactive Distillation, W. Qi, M. F. Malone
Michael F. Malone
This Article provides new predictions for selectivity in batch reactive distillation, identifying the reflux or reboil ratio and a Damkhler number (Da) as the key operating parameters. The dimensionless Da incorporates the influence of liquid holdup, vapor rate, and rate of reaction. Example results for a system of serial isomerization reactions and for the synthesis of ethylene glycol are provided. The results show that selectivity improvements in BRD are limited for high values of Da or for high values of the reflux or reboil ratio and that selectivity is enhanced as Da or reflux or reboil ratio is decreased. However, …
Dynamic Flux Balance Modeling Of Microbial Co-Cultures For Efficient Batch Fermentation Of Glucose And Xylose Mixtures, Timothy J. Hanly, Michael A. Henson
Dynamic Flux Balance Modeling Of Microbial Co-Cultures For Efficient Batch Fermentation Of Glucose And Xylose Mixtures, Timothy J. Hanly, Michael A. Henson
Michael A Henson
Sequential uptake of pentose and hexose sugars that compose lignocellulosic biomass limits the ability of pure microbial cultures to efficiently produce value-added bioproducts. In this work, we used dynamic flux balance modeling to examine the capability of mixed cultures of substrate-selective microbes to improve the utilization of glucose/xylose mixtures and to convert these mixed substrates into products. Co-culture simulations of Escherichia coli strains ALS1008 and ZSC113, engineered for glucose and xylose only uptake respectively, indicated that improvements in batch substrate consumption observed in previous experimental studies resulted primarily from an increase in ZSC113 xylose uptake relative to wild-type E. coli. …
Mechanistic Modelling Of Dynamic Mri Data Predicts That Tumour Heterogeneity Decreases Therapeutic Response, R Venkatasubramanian, Rb Arenas, Michael A. Henson, Ns Forbes
Mechanistic Modelling Of Dynamic Mri Data Predicts That Tumour Heterogeneity Decreases Therapeutic Response, R Venkatasubramanian, Rb Arenas, Michael A. Henson, Ns Forbes
Michael A Henson
BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) contains crucial information about tumour heterogeneity and the transport limitations that reduce drug efficacy. Mathematical modelling of drug delivery and cellular responsiveness based on underutilised DCE-MRI data has the unique potential to predict therapeutic responsiveness for individual patients. METHODS: To interpret DCE-MRI data, we created a modelling framework that operates over multiple time and length scales and incorporates intracellular metabolism, nutrient and drug diffusion, trans-vascular permeability, and angiogenesis. The computational methodology was used to analyse DCE-MR images collected from eight breast cancer patients at Baystate Medical Center in Springfield, MA. RESULTS: Computer simulations …
Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy
Contact Angle Hysteresis: A Different View And A Trivial Recipe For Low Hysteresis Hydrophobic Surfaces, Joseph W. Krumpfer, Thomas J. Mccarthy
Thomas J. McCarthy
Contact angle hysteresis is addressed from two perspectives. The first is an analysis of the events that occur during motion of droplets on superhydrophobic surfaces. Hysteresis is discussed in terms of receding contact line pinning and the tensile failure of capillary bridges. The sign of the curvature of the solid surface is implicated as playing a key role. The second is the report of a new method to prepare smooth low hysteresis surfaces. The thermal treatment of oxygen plasma-cleaned silicon wafers with trimethylsilyl-terminated linear poly(dimethylsiloxane) (PDMS - commercial silicone oils) in disposable glass vessels is described. This treatment renders silicon/silica …
Characterization Of Aggregate Size In Taxus Suspension Cell Culture, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts
Characterization Of Aggregate Size In Taxus Suspension Cell Culture, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts
Michael A Henson
Plant cells grow as aggregates in suspension culture, but little is known about the dynamics of aggregation, and no routine methodology exists to measure aggregate size. In this study, we evaluate several different methods to characterize aggregate size in Taxus suspension cultures, in which aggregate diameters range from 50 μm to 2000 μm, including filtration and image analysis, and develop a novel method using a specially equipped Coulter counter system. We demonstrate the suitability of this technology to measure plant cell culture aggregates, and show that it can be reliably used to measure total biomass accumulation compared to standard methods …
A Multiscale Model To Investigate Circadian Rhythmicity Of Pacemaker Neurons In The Suprachiasmatic Nucleus, Christina Vasalou, Michael A. Henson
A Multiscale Model To Investigate Circadian Rhythmicity Of Pacemaker Neurons In The Suprachiasmatic Nucleus, Christina Vasalou, Michael A. Henson
Michael A Henson
The suprachiasmatic nucleus (SCN) of the hypothalamus is a multicellular system that drives daily rhythms in mammalian behavior and physiology. Although the gene regulatory network that produces daily oscillations within individual neurons is well characterized, less is known about the electrophysiology of the SCN cells and how firing rate correlates with circadian gene expression. We developed a firing rate code model to incorporate known electrophysiological properties of SCN pacemaker cells, including circadian dependent changes in membrane voltage and ion conductances. Calcium dynamics were included in the model as the putative link between electrical firing and gene expression. Individual ion currents …
Electromechanically Driven Chaotic Dynamics Of Voids In Metallic Thin Films, Dimitrios Maroudas, M. R. Gungor, V. Tomar
Electromechanically Driven Chaotic Dynamics Of Voids In Metallic Thin Films, Dimitrios Maroudas, M. R. Gungor, V. Tomar
Dimitrios Maroudas
We report a systematic investigation of complex asymptotic states reached in the electromigration-driven morphological evolution of void surfaces in thin films of face-centered cubic metals with ⟨110⟩- and ⟨100⟩-oriented film planes under the simultaneous action of biaxial tension. The analysis is based on self-consistent dynamical simulations according to a realistic, well-validated, and fully nonlinear model. For ⟨110⟩-oriented film planes, we show that upon increasing the applied mechanical stress level, morphologically stable steady states transition to time-periodic states through a subcritical Hopf bifurcation. Further increase in the stress level triggers a sequence of period-doubling bifurcations that sets the driven nonlinear system …
Improved Utilization Of Biomass-Derived Carbon By Millisecond Co-Processing With Hydrogen Rich Feedstocks, Paul J. Dauenhauer, J. L. Colby, A. Bhan, L. D. Schmitt
Improved Utilization Of Biomass-Derived Carbon By Millisecond Co-Processing With Hydrogen Rich Feedstocks, Paul J. Dauenhauer, J. L. Colby, A. Bhan, L. D. Schmitt
Paul J. Dauenhauer
A reactor capable of improving the utilization of biomass-derived carbon during thermochemical conversion to synthesis gas is demonstrated experimentally. By co-processing hydrogen-deficient biomass (H/C[similar]2) with hydrogen-rich feedstocks (H/C≥4) through catalytic partial oxidation, 100% of the fuel carbon atoms fed to the reactor can be converted to CO.
Predicting Bite Force In Mammals: Two-Dimensional Versus Three-Dimensional Lever Models, Jl Davis, Se Santana, Er Dumont, Ir Grosse
Predicting Bite Force In Mammals: Two-Dimensional Versus Three-Dimensional Lever Models, Jl Davis, Se Santana, Er Dumont, Ir Grosse
Jeffrey M. Davis
Bite force is a measure of whole-organism performance that is often used to investigate the relationships between performance, morphology and fitness. When in vivo measurements of bite force are unavailable, researchers often turn to lever models to predict bite forces. This study demonstrates that bite force predictions based on two-dimensional (2-D) lever models can be improved by including three-dimensional (3-D) geometry and realistic physiological cross-sectional areas derived from dissections. Widely used, the 2-D method does a reasonable job of predicting bite force. However, it does so by over predicting physiological cross-sectional areas for the masseter and pterygoid muscles and under …
Kinetics Of Furfural Production By Dehydration Of Xylose In A Biphasic Reactor With Microwave Heating, George W. Huber, R. Weingarten, J. Cho, W. C. Conner Jr.
Kinetics Of Furfural Production By Dehydration Of Xylose In A Biphasic Reactor With Microwave Heating, George W. Huber, R. Weingarten, J. Cho, W. C. Conner Jr.
George W. Huber
In this paper we report a kinetic model for the dehydration of xylose to furfural in a biphasic batch reactor with microwave heating. There are four key steps in our kinetic model: (1) xylose dehydration to form furfural; (2) furfural reaction to form degradation products; (3) furfural reaction with xylose to form degradation products, and (4) mass transfer of furfural from the aqueous phase into the organic phase (methyl isobutyl ketone - MIBK). This kinetic model was used to fit experimental data collected in this study. The apparent activation energy for xylose dehydration is higher than the apparent activation energy …
Probing The Mechanism Of Silica Polymerization At Ambient Temperatures Using Monte Carlo Simulations, Peter A. Monson, Ateeque Malani, Scott M. Auerbach
Probing The Mechanism Of Silica Polymerization At Ambient Temperatures Using Monte Carlo Simulations, Peter A. Monson, Ateeque Malani, Scott M. Auerbach
Peter A. Monson
We have developed a model for silica polymerization at ambient temperatures and low densities and have studied this using reactive Monte Carlo simulations. The model focuses on SiO4 coordination with the energetics of hydrolysis and condensation reactions treated via the reaction ensemble. The simplicity of the model makes large system sizes accessible on a modest computation budget, although it is necessary to make additional assumptions in order to use the reactive Monte Carlo method as a simulation of the system dynamics. Excellent agreement for the evolution of the Qn distribution is obtained upon comparing the simulation results to experimental observations. …
Modeling Nanoparticle Formation During Early Stages Of Zeolite Growth: A Low-Coordination Lattice Model Of Template Penetration, Peter A. Monson, L. Jin, Scott M. Auerbach
Modeling Nanoparticle Formation During Early Stages Of Zeolite Growth: A Low-Coordination Lattice Model Of Template Penetration, Peter A. Monson, L. Jin, Scott M. Auerbach
Peter A. Monson
We present an extension of the simple-cubic lattice model developed by Jorge et al. [ J. Am. Chem. Soc. 2005, 127, 14388] of nanoparticle growth in the clear solution synthesis of silicalite-1 (MFI). We have implemented the model on a body-center cubic (bcc) lattice with second-neighbor repulsions, to generate a four-coordinate network that mimics the tetrahedral structure of silica. With this low-coordination lattice model we observe that the nanoparticles are metastable, possessing a core−shell structure with mostly silica in the core and templates forming a shell. Nanoparticle size is found to increase with temperature and decrease with solution pH, in …
Stabilization Of Thin Liquid Films Flowing Over Locally Heated Surfaces Via Substrate Topography, N Tiwari, Jm Davis
Stabilization Of Thin Liquid Films Flowing Over Locally Heated Surfaces Via Substrate Topography, N Tiwari, Jm Davis
Jeffrey M. Davis
A long-wave lubrication analysis is used to study the influence of topographical features on the linear stability of noninertial coating flows over a locally heated surface. Thin liquid films flowing over surfaces with localized heating develop a pronounced ridge at the upstream edge of the heater. This ridge becomes unstable to transverse perturbations above a critical Marangoni number and evolves into an array of rivulets even in the limit of noninertial flow. Similar fluid ridges form near topographical variations on isothermal surfaces, but these ridges are stable to perturbations. The influence of basic topographical features on the stability of the …
Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew
Apolar Ortho-Phenylene Ethynylene Oligomers: Conformational Ordering Without Intermolecular Aggregation, Jing Jiang, Morris M. Slutsky, Ticora V. Jones, Gregory N. Tew
Gregory N. Tew
This paper describes the characterization of solvent induced folding behavior for non-polar (NP) alkoxy substituted ortho-phenylene ethynylene (o-PE) oligomers. Oligomers of lengths up to nine units have been shown to adopt helical conformations in heptane by NMR and CD spectroscopy, while chloroform promotes extended conformations. Surprisingly, the molar ellipticity values found in heptane for these oligomers are very small compared to other literature values of meta-phenylene ethynylene (m-PE) folded systems; however, comparable molar ellipticity values were found for a closed macrocyclic o-PE suggesting the weak ellipticity is a molecular-feature rather than a quality of folding indicator.