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Articles 121 - 140 of 140
Full-Text Articles in Engineering
Working With The Engineering Design Process, Thomas Gralinski
Working With The Engineering Design Process, Thomas Gralinski
Science and Engineering Saturday Seminars
No abstract provided.
Mechanical Behavior Of Ultra-Low-Dielectric-Constant Mesoporous Amorphous Silica, Dimitrios Maroudas, M. R. Gungor, J. J. Watkins
Mechanical Behavior Of Ultra-Low-Dielectric-Constant Mesoporous Amorphous Silica, Dimitrios Maroudas, M. R. Gungor, J. J. Watkins
Dimitrios Maroudas
We report results for the dependence of the mechanical properties of ordered mesoporous silica structures on the pore diameter based on molecular-dynamics simulations. We examine structures with spherical pores arranged in a simple cubic lattice and cylindrical pores arranged in a square lattice subjected to uniaxial tension and compression; for the structures with cylindrical pores, both radial and axial loading is studied with respect to the pore orientation. Our analysis provides a unifying explanation to the observed mechanical response based on the mechanical loading effects on the pore wall thickness.
Chemistry Of Furan Conversion Into Aromatics And Olefins Over Hzsm-5: A Model Biomass Conversion Reaction, George W. Huber, Y. Cheng
Chemistry Of Furan Conversion Into Aromatics And Olefins Over Hzsm-5: A Model Biomass Conversion Reaction, George W. Huber, Y. Cheng
George W. Huber
The conversion of furan (a model of cellulosic biomass) over HZSM-5 was investigated in a thermogravimetric analysis–mass spectrometry system, in situ Fourier transform infrared analysis, and in a continuous-flow fixed-bed reactor. Furan adsorbed as oligomers at room temperature with a 1.73 of adsorbed furan/Al ratio. These oligomers were polycyclic aromatic compounds that were converted to CO, CO2, aromatics, and olefins at temperatures from 400 to 600 °C. Aromatics (e.g., benzene, toluene, and naphthalene), oligomer isomers (e.g., benzofuran, 2,2-methylenebisfuran, and benzodioxane), and heavy oxygenates (C12+ oligomers) were identified as intermediates formed inside HZSM-5 at different reaction temperatures. During furan conversion, graphite-type …
Catalytic Conversion Of Biomass-Derived Feedstocks Into Olefins And Aromatics With Zsm-5: The Hydrogen To Carbon Effective Ratio, George W. Huber, H. Zhang, Y. Cheng, T. P. Vispute, R. Xiao
Catalytic Conversion Of Biomass-Derived Feedstocks Into Olefins And Aromatics With Zsm-5: The Hydrogen To Carbon Effective Ratio, George W. Huber, H. Zhang, Y. Cheng, T. P. Vispute, R. Xiao
George W. Huber
Catalytic conversion of ten biomass-derived feedstocks, i.e. glucose, sorbitol, glycerol, tetrahydrofuran, methanol and different hydrogenated bio-oil fractions, with different hydrogen to carbon effective (H/Ceff) ratios was conducted in a gas-phase flow fixed-bed reactor with a ZSM-5 catalyst. The aromatic + olefin yield increases and the coke yield decreases with increasing H/Ceff ratio of the feed. There is an inflection point at a H/Ceff ratio = 1.2, where the aromatic + olefin yield does not increase as rapidly as it does prior to this point. The ratio of olefins to aromatics also increases with increasing H/Ceff ratio. CO and CO2 yields …
Analysis Of Aggregate Size As A Process Variable Affecting Paclitaxel Accumulation In Taxus Suspension Cultures, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts
Analysis Of Aggregate Size As A Process Variable Affecting Paclitaxel Accumulation In Taxus Suspension Cultures, Martin E. Kolewe, Michael A. Henson, Susan C. Roberts
Michael A Henson
Plant cell aggregates have long been implicated in affecting cellular metabolism in suspension culture, yet the rigorous characterization of aggregate size as a process variable and its effect on bioprocess performance has not been demonstrated. Aggregate fractionation and analysis of biomass-associated product is commonly used to assess the effect of aggregation, but we establish that this method is flawed under certain conditions and does not necessarily agree with comprehensive studies of total culture performance. Leveraging recent advances to routinely measure aggregate size distributions, we developed a simple method to manipulate aggregate size and evaluate its effect on the culture as …
Modeling Silicic Acid Polymerization Using A Low Coordination Lattice Model, Peter A. Monson, Scott M. Auerbach, Lin Jin
Modeling Silicic Acid Polymerization Using A Low Coordination Lattice Model, Peter A. Monson, Scott M. Auerbach, Lin Jin
Peter A. Monson
We present an atomic lattice model for studying the polymerization of silicic acid in sol-gel and related processes for synthesizing silica materials. Our model is based on Si and O atoms occupying the sites of a body-centered-cubic lattice, with all atoms arranged in SiO4 tetrahedra. This is the simplest model that allows for variation in the Si–O–Si angle, which is largely responsible for the versatility in silica polymorphs. The model describes the assembly of polymerized silica structures starting from a solution of silicic acid in water at a given concentration and pH. This model can simulate related materials—chalcogenides and clays—by …
Simulating Infrared Spectra And Hydrogen Bonding In Cellulose Iβ At Elevated Temperatures, George W. Huber, V. Agarwal, W. C. Conner Jr.
Simulating Infrared Spectra And Hydrogen Bonding In Cellulose Iβ At Elevated Temperatures, George W. Huber, V. Agarwal, W. C. Conner Jr.
George W. Huber
We have modeled the transformation of cellulose Iβ to a high temperature (550 K) structure, which is considered to be the first step in cellulose pyrolysis. We have performed molecular dynamics simulations at constant pressure using the GROMOS 45a4 united atom forcefield. To test the forcefield, we computed the density, thermal expansion coefficient, total dipole moment, and dielectric constant of cellulose Iβ, finding broad agreement with experimental results. We computed infrared (IR) spectra of cellulose Iβ over the range 300–550 K as a probe of hydrogen bonding. Computed IR spectra were found to agree semi-quantitatively with experiment, especially in the …
Production Of Green Aromatics And Olefins By Catalytic Fast Pyrolysis Of Wood Sawdust, George W. Huber, T. R. Carlson, Y. -T Cheng, J Jae
Production Of Green Aromatics And Olefins By Catalytic Fast Pyrolysis Of Wood Sawdust, George W. Huber, T. R. Carlson, Y. -T Cheng, J Jae
George W. Huber
Catalytic fast pyrolysis of pine wood sawdust and furan (a model biomass compound) with ZSM-5 based catalysts was studied with three different reactors: a bench scale bubbling fluidized bed reactor, a fixed bed reactor and a semi-batch pyroprobe reactor. The highest aromatic yield from sawdust of 14% carbon in the fluidized bed reactor was obtained at low biomass weight hourly space velocities (less than 0.5 h−1) and high temperature (600 °C). Olefins (primarily ethylene and propylene) were also produced with a carbon yield of 5.4% carbon. The biomass weight hourly space velocity and the reactor temperature can be used to …
Production Of Furfural And Carboxylic Acids From Waste Aqueous Hemicellulose Solutions From The Pulp And Paper And Cellulosic Ethanol Industries, George W. Huber, R. Xing, W. Qi
Production Of Furfural And Carboxylic Acids From Waste Aqueous Hemicellulose Solutions From The Pulp And Paper And Cellulosic Ethanol Industries, George W. Huber, R. Xing, W. Qi
George W. Huber
In this paper we present a new process to produce furfural and co-products of formic and acetic acids from waste aqueous hemicellulose solutions using a continuous two zone biphasic reactor. We estimate this approach uses 67% to 80% less energy than the current industrial processes to produce furfural. An economic analysis indicates that furfural can be produced with this process at 366 US$ per metric ton which is 25% of the selling price of furfural in the U.S. market today. This analysis assumes a plant capacity of 78 kiloton per year of furfural, 12 kiloton per year of formic acid …
Aerosol Generation By Reactive Boiling Ejection Of Molten Cellulose, Paul J. Dauenhauer, A. R. Teixeira, K. G. Mooney, J. S. Kruger, C. L. Williams, W. J. Suszynski, L. D. Schmidt, D. P. Schmidt
Aerosol Generation By Reactive Boiling Ejection Of Molten Cellulose, Paul J. Dauenhauer, A. R. Teixeira, K. G. Mooney, J. S. Kruger, C. L. Williams, W. J. Suszynski, L. D. Schmidt, D. P. Schmidt
Paul J. Dauenhauer
The generation of primary aerosols from biomass hinders the production of biofuels by pyrolysis, intensifies the environmental impact of forest fires, and exacerbates the health implications associated with cigarette smoking. High speed photography is utilized to elucidate the ejection mechanism of aerosol particles from thermally decomposing cellulose at the timescale of milliseconds. Fluid modeling, based on first principles, and experimental measurement of the ejection phenomenon supports the proposed mechanism of interfacial gas bubble collapse forming a liquid jet which subsequently fragments to form ejected aerosol particles capable of transporting nonvolatile chemicals. Identification of the bubble-collapse/ejection mechanism of intermediate cellulose confirms …
Renewable Gasoline From Aqueous Phase Hydrodeoxygenation Of Aqueous Sugar Solutions Prepared By Hydrolysis Of Maple Wood, George W. Huber, N. Li, G. A. Tompsett, T. Zhang, J. Shi, C. E. Wyman
Renewable Gasoline From Aqueous Phase Hydrodeoxygenation Of Aqueous Sugar Solutions Prepared By Hydrolysis Of Maple Wood, George W. Huber, N. Li, G. A. Tompsett, T. Zhang, J. Shi, C. E. Wyman
George W. Huber
In this paper we demonstrate an integrated process for the production of high octane gasoline from maple wood by hydrolysis of maple wood into aqueous carbohydrate solutions followed by aqueous phase hydrodeoxygenation of the sugar solutions. The aqueous carbohydrate solutions were prepared by both hydrolysis in hot water and hydrolysis with dilute acids (H2SO4, oxalic acid). The aqueous carbohydrate solutions were a mixture of xylose, water soluble hemicellulose oligomers, acetic acid, glucose, glucose oligomers, and probably some lignin polymers. Hydrolysis with hot water produced primarily hemicellulose oligomers whereas hydrolysis with acids produced mainly xylose and acetic acid. The hydrolysis co-product …
Asymmetry In Chemical Structures And In Life: My Last Two Articles, Otto Vogl
Asymmetry In Chemical Structures And In Life: My Last Two Articles, Otto Vogl
Otto Vogl
No abstract provided.
Room Temperature Magnetic Materials From Nanostructured Diblock Copolymers, Zoha M. Al-Badri, Raghavendra R. Maddikeri, Yongping Zha, Hitesh D. Thaker, Priyanka Dobriyal, Raja Shunmugam, Thomas P. Russell, Gregory N. Tew
Room Temperature Magnetic Materials From Nanostructured Diblock Copolymers, Zoha M. Al-Badri, Raghavendra R. Maddikeri, Yongping Zha, Hitesh D. Thaker, Priyanka Dobriyal, Raja Shunmugam, Thomas P. Russell, Gregory N. Tew
Gregory N. Tew
Nanostructured magnetic materials are important for many advanced applications. Consequently, new methods for their fabrication are critical. However, coupling self-assembly to the generation of magnetic materials in a simple, straight-forward manner has remained elusive. Although several approaches have been considered, most have multiple processing steps, thus diminishing their use of self-assembly to influence magnetic properties. Here we develop novel block copolymers that are preprogrammed with the necessary chemical information to microphase separate and deliver room temperature ferromagnetic properties following a simple heat treatment. The importance of the nanostructured confinement is demonstrated by comparison with the parent homopolymer, which provides only …
Depletion Versus Deflection: How Membrane Bending Can Influence Adhesion, Jin Nam, Maria Santore
Depletion Versus Deflection: How Membrane Bending Can Influence Adhesion, Jin Nam, Maria Santore
Maria Santore
During depletion-driven vesicle adhesion, a stiff membrane’s resistance to bending at fixed tension prevents contact angle equilibrium and vesicle spreading over an opposing vesicle, while more flexible vesicles partially engulf opposing vesicles. Estimates of the bending cost associated with the spreading contact line, relative to the adhesion energy, were consistent with the observed spreading or lack of spreading for the flexible and stiff membranes, respectively, and predicted a lag time sometimes preceding spreading.
Synthesis Of Hydrogels Via Ring-Opening Metathesis Polymerization: Factors Affecting Gelation, Gregory N. Tew, Ahmad E. Madkour, Joshua M. Grolman
Synthesis Of Hydrogels Via Ring-Opening Metathesis Polymerization: Factors Affecting Gelation, Gregory N. Tew, Ahmad E. Madkour, Joshua M. Grolman
Gregory N. Tew
Ring-opening metathesis polymerization (ROMP) was used to synthesize hydrogels via copolymerization of a diamine monomer 3 and a novel cross-linker 5 using Grubbs' third generation catalyst as initiator. Reactions were performed at two different monomer concentrations and at various initial molar ratios of cross-linker to initiator. At low monomer concentration, gelation occurred at initial cross-linker to initiator ratios of 1.5 and greater, which decreased to values of 1.05 and greater when increasing the monomer concentration. This result is in agreement with the Flory–Stockmayer theory. The gel yield and swelling properties were also found to be dependent on the cross-linker to …
Center Of Umass – Industry Research On Polymers: Cumirp: Inception And Founding, Otto Vogl
Center Of Umass – Industry Research On Polymers: Cumirp: Inception And Founding, Otto Vogl
Otto Vogl
No abstract provided.
Polymer Science And The Arts: Oriental Lacquer, Otto Vogl
Polymer Science And The Arts: Oriental Lacquer, Otto Vogl
Otto Vogl
No abstract provided.
Cavitation Rheology Of The Eye Lens, Alfred Crosby, Jun Cui, Cheol Hee Lee, Aline Delbos, Jennifer J. Mcmanus
Cavitation Rheology Of The Eye Lens, Alfred Crosby, Jun Cui, Cheol Hee Lee, Aline Delbos, Jennifer J. Mcmanus
Alfred Crosby
The anisotropic mechanical properties of bovine eye lenses were measured using cavitation rheology over a range of length scales. The technique involves inducing a cavity at the tip of a syringe needle in different regions of the lens. Effective Young's moduli of the nucleus and cortex of the lens were determined, as approximately 11.8 and 0.8 kPa, respectively, on macroscopic length scales. We also measured the mechanical properties of the lens on the length scale of a single cell, suggesting that the stiffness significantly decreased from that in the bulk measurements for both the nucleus and cortex. In addition, during …
Multiscale Modeling Of Traffic Flow, Daiheng Ni
Multiscale Modeling Of Traffic Flow, Daiheng Ni
Daiheng Ni
This paper presents a broad perspective on traffic flow modeling at a spectrum of four scales. Modeling objective and model properties at each scale are discussed and existing efforts are reviewed. In order to ensure modeling consistency and provide a microscopic basis for macroscopic models, it is critical to address the coupling among models at different scales, i.e. how less detailed models are derived from more detailed models and, conversely, how more detailed models are aggregated to less detailed models. With this understanding, a consistent modeling approach is proposed based on field theory and modeling strategies at each of the …
Ultrasensitive Detection Of Rare Mutations Using Next-Generation Targeted Resequencing, Patrick Flaherty, Georges Natsoulis, Omkar Muralidharan, Mark Winters, Jason Buenrostro, John Bell, Sheldon Brown, Mark Holodniy, Nancy Zhang, Hanlee P. Ji
Ultrasensitive Detection Of Rare Mutations Using Next-Generation Targeted Resequencing, Patrick Flaherty, Georges Natsoulis, Omkar Muralidharan, Mark Winters, Jason Buenrostro, John Bell, Sheldon Brown, Mark Holodniy, Nancy Zhang, Hanlee P. Ji
Mathematics and Statistics Department Faculty Publication Series
With next-generation DNA sequencing technologies, one can interrogate a specific genomic region of interest at very high depth of coverage and identify less prevalent, rare mutations in heterogeneous clinical samples. However, the mutation detection levels are limited by the error rate of the sequencing technology as well as by the availability of variant-calling algorithms with high statistical power and low false positive rates. We demonstrate that we can robustly detect mutations at 0.1% fractional representation. This represents accurate detection of one mutant per every 1000 wild-type alleles. To achieve this sensitive level of mutation detection, we integrate a high accuracy …