Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Keyword
-
- Geological and Atmospheric Sciences (4)
- Catalyst (3)
- Carbon nanotube (2)
- Catalysis (2)
- Cell migration (2)
-
- Fibroblast (2)
- Fluorescence microscopy (2)
- Molecular stability (2)
- Phosphatidylinositide (2)
- Platelet derived growth factor (2)
- Signal transduction (2)
- Silicon carbide (2)
- 3' phosphoinositide (1)
- Acetic acid derivative (1)
- Agronomy (1)
- Aluminum (1)
- Amine (1)
- Analytical transmission electron microscopy (1)
- Anisole (1)
- Aqueous solubility (1)
- Benzoylation (1)
- Biodegradation (1)
- Biosynthesis (1)
- Biotransformation (1)
- Brevibacerium (1)
- Carbon nanofiber (1)
- Carbon nanotubes (1)
- Carbon-based (1)
- Cell Polarity (1)
- Cell membrane (1)
- Publication Year
- Publication
- File Type
Articles 1 - 30 of 36
Full-Text Articles in Biological Engineering
Epitaxially Grown Collagen Fibrils Reveal Diversity In Contact Guidance Behavior Among Cancer Cells, Juan Wang, Joseph W. Petefish, Andrew C. Hillier, Ian C. Schneider
Epitaxially Grown Collagen Fibrils Reveal Diversity In Contact Guidance Behavior Among Cancer Cells, Juan Wang, Joseph W. Petefish, Andrew C. Hillier, Ian C. Schneider
Andrew C. Hillier
Invasion of cancer cells into the surrounding tissue is an important step during cancer progression and is driven by cell migration. Cell migration can be random, but often it is directed by various cues such as aligned fibers composed of extracellular matrix (ECM), a process called contact guidance. During contact guidance, aligned fibers bias migration along the long axis of the fibers. These aligned fibers of ECM are commonly composed of type I collagen, an abundant structural protein around tumors. In this paper, we epitaxially grew several different patterns of organized type I collagen on mica and compared the morphology …
Three-Dimensional Confocal Microscopy Indentation Method For Hydrogel Elasticity Measurement, Donghee Lee, Md Mahmudur Rahman, You Zhou, Sangjin Ryu
Three-Dimensional Confocal Microscopy Indentation Method For Hydrogel Elasticity Measurement, Donghee Lee, Md Mahmudur Rahman, You Zhou, Sangjin Ryu
Md Mahmudur Rahman
No abstract provided.
Angle-Tunable Enhanced Infrared Reflection Absorption Spectroscopy Via Grating-Coupled Surface Plasmon Resonance, Joseph W. Petefish, Andrew C. Hillier
Angle-Tunable Enhanced Infrared Reflection Absorption Spectroscopy Via Grating-Coupled Surface Plasmon Resonance, Joseph W. Petefish, Andrew C. Hillier
Andrew C. Hillier
Surface enhanced infrared absorption (SEIRA) spectroscopy is an attractive method for increasing the prominence of vibrational modes in infrared spectroscopy. To date, the majority of reports associated with SEIRA utilize localized surface plasmon resonance from metal nanoparticles to enhance electromagnetic fields in the region of analytes. Limited work has been performed using propagating surface plasmons as a method for SEIRA excitation. In this report, we demonstrate angle-tunable enhancement of vibrational stretching modes associated with a thin poly(methyl methacrylate) (PMMA) film that is coupled to a silver-coated diffraction grating. Gratings are fabricated using laser interference lithography to achieve precise surface periodicities, …
Electrochemically Modulated Permeability Of Poly(Aniline) And Composite Poly(Aniline)−Poly(Styrenesulfonate) Membranes, D. L. Pile, Y. Zhang, Andrew C. Hillier
Electrochemically Modulated Permeability Of Poly(Aniline) And Composite Poly(Aniline)−Poly(Styrenesulfonate) Membranes, D. L. Pile, Y. Zhang, Andrew C. Hillier
Andrew C. Hillier
The influence of oxidation state on the permeability of several probe molecules through conducting polymer membranes comprising composites of poly(aniline) and poly(styrenesulfonate) was examined in aqueous solution. Pure poly(aniline) membranes displayed a characteristic increase in permeability between reduced and half-oxidized states for neutrally charged phenol and negatively charged 4-hydroxybenzenesulfonate. In contrast, positively charged pyridine experienced decreased permeability through the membrane when poly(aniline) was switched from the reduced to the half-oxidized state. This behavior can be explained by a combination of oxidation-induced film swelling and the anion-exchange character of the positively charged membrane. The membrane composition was modified to include a …
Scanning Electrochemical Mapping Of Spatially Localized Electrochemical Reactions Induced By Surface Potential Gradients, Shrisudersan Jayaraman, Erin L. May, Andrew C. Hillier
Scanning Electrochemical Mapping Of Spatially Localized Electrochemical Reactions Induced By Surface Potential Gradients, Shrisudersan Jayaraman, Erin L. May, Andrew C. Hillier
Andrew C. Hillier
The influence of a surface potential gradient on the location and extent of electrochemical reactions was examined using a scanning electrochemical microscope. A linear potential gradient was imposed on the surface of a platinum-coated indium tin oxide electrode by applying two different potential values at the edges of the electrode. The applied potentials were used to control the location and extent of several electrochemical reactions, including the oxidation of Ru(NH3)62+, the oxidation of H2, and the oxidation of H2 in the presence of adsorbed CO. Scanning electrochemical mapping of these reactions was achieved by probing the feedback current associated with …
Organic Materials And Organic/Inorganic Heterostructures In Atom Probe Tomography, Derk Joester, Andrew C. Hillier, Yi Zhang, Ty J. Prosa
Organic Materials And Organic/Inorganic Heterostructures In Atom Probe Tomography, Derk Joester, Andrew C. Hillier, Yi Zhang, Ty J. Prosa
Andrew C. Hillier
Nano-scale organic/inorganic interfaces are key to a wide range of materials. In many biominerals, for instance bone or teeth, outstanding fracture toughness and wear resistance can be attributed to buried organic/inorganic interfaces. Organic/inorganic interfaces at very small length scales are becoming increasingly important also in nano and electronic materials. For example, functionalized inorganic nanomaterials have great potential in biomedicine or sensing applications. Thin organic films are used to increase the conductivity of LiFePO4 electrodes in lithium ion batteries, and solid electrode interphases (SEI) form by uncontrolled electrolyte decomposition. Organics play a key role in dye-sensitized solar cells, organic photovoltaics, and …
Resonance Quenching And Guided Modes Arising From The Coupling Of Surface Plasmons With A Molecular Resonance, Wei-Hsun Yeh, Joseph W. Petefish, Andrew C. Hillier
Resonance Quenching And Guided Modes Arising From The Coupling Of Surface Plasmons With A Molecular Resonance, Wei-Hsun Yeh, Joseph W. Petefish, Andrew C. Hillier
Andrew C. Hillier
In this paper, we describe experimental and modeling results that illucidate the nature of coupling between surface plasmon polaritons in a thin silver film with the molecular resonance of a zinc phthalocyanine dye film. This coupling leads to several phenomena not generally observed when plasmons are coupled to transparent materials. The increased absorption coefficient near a molecular resonance leads to a discontinuity in the refractive index, which causes branching of the plasmon resonance condition and the appearance of two peaks in the p-polarized reflectance spectrum. A gap exists between these peaks in the region of the spectrum associated with the …
Three-Dimensional Atom Probe Tomography Of Oxide, Anion, And Alkanethiolate Coatings On Gold, Yi Zhang, Andrew C. Hillier
Three-Dimensional Atom Probe Tomography Of Oxide, Anion, And Alkanethiolate Coatings On Gold, Yi Zhang, Andrew C. Hillier
Andrew C. Hillier
We have used three-dimensional atom probe tomography to analyze several nanometer-thick and monomolecular films on gold surfaces. High-purity gold wire was etched by electropolishing to create a sharp tip suitable for field evaporation with a radius of curvature of layer, primarily consisting of water and atmospheric gases, was observed on a fresh tip. This sample exhibited crystalline lattice spacings consistent with the interlayer spacing of {200} lattice planes of bulk gold. A thin oxide layer was created on the gold surface via plasma oxidation, and the thickness and composition of this layer was measured. Clear evidence of a nanometer-thick oxide …
Wavelength Tunable Surface Plasmon Resonance-Enhanced Optical Transmission Through A Chirped Diffraction Grating, Wei-Hsun Yeh, Justin Kleingartner, Andrew C. Hillier
Wavelength Tunable Surface Plasmon Resonance-Enhanced Optical Transmission Through A Chirped Diffraction Grating, Wei-Hsun Yeh, Justin Kleingartner, Andrew C. Hillier
Andrew C. Hillier
We report the construction and testing of a chirped diffraction grating, which serves as a substrate for surface plasmon-enhanced optical transmission. This grating possesses a spatial variation in both pitch and amplitude along its surface. It was created by plasma oxidation of a curved poly(dimethoxysilane) sheet, which resulted in nonuniform buckling along the polymer surface. A gold-coated replica of this surface elicited an optical response that consisted of a series of narrow, enhanced transmission peaks spread over the visible spectrum. The location and magnitude of these transmission peaks varied along the surface of the grating and coincided with conditions where …
High Rate Detection Of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining An Electrode-Coated Membrane With Hydrodynamic Flow In A Wall-Tube Configuration, Subramanian Venkatachalam, Robert J. Angelici, L. Keith Woo, Andrew C. Hillier
High Rate Detection Of Volatile Products Using Differential Electrochemical Mass Spectrometry: Combining An Electrode-Coated Membrane With Hydrodynamic Flow In A Wall-Tube Configuration, Subramanian Venkatachalam, Robert J. Angelici, L. Keith Woo, Andrew C. Hillier
Andrew C. Hillier
We present an experimental system that combines differential electrochemical mass spectrometry with hydrodynamic flow consisting of an impinging jet in a wall-tube configuration. This assembly allows simultaneous detection of electrochemical signals along with monitoring of dissolved gas species using differential electrochemical mass spectrometry under well-defined hydrodynamic conditions and over a wide range of mass transfer rates. The working electrode is deposited directly onto a thin, hydrophobic membrane, which also serves as the inlet to the mass spectrometer. This inlet provides extremely rapid mass detection as well as a high flux of products from the electrode surface into the mass spectrometer. …
Diffraction-Based Tracking Of Surface Plasmon Resonance Enhanced Transmission Through A Gold-Coated Grating, Wei-Hsun Yeh, Joseph W. Petefish, Andrew C. Hillier
Diffraction-Based Tracking Of Surface Plasmon Resonance Enhanced Transmission Through A Gold-Coated Grating, Wei-Hsun Yeh, Joseph W. Petefish, Andrew C. Hillier
Andrew C. Hillier
Surface plasmon resonance enhanced transmission through metal-coated nanostructures represents a highly sensitive yet simple method for quantitative measurement of surface processes and is particularly useful in the development of thin film and adsorption sensors. Diffraction-induced surface plasmon excitation can produce enhanced transmission at select regions of the visible spectrum, and wavelength shifts associated with these transmission peaks can be used to track adsorption processes and film formation. In this report, we describe a simple optical microscope-based method for monitoring the first-order diffracted peaks associated with enhanced transmission through a gold-coated diffraction grating. A Bertrand lens is used to focus the …
Use Of Dispersion Imaging For Grating-Coupled Surface Plasmon Resonance Sensing Of Multilayer Langmuir–Blodgett Films, Wei-Hsun Yeh, Andrew C. Hillier
Use Of Dispersion Imaging For Grating-Coupled Surface Plasmon Resonance Sensing Of Multilayer Langmuir–Blodgett Films, Wei-Hsun Yeh, Andrew C. Hillier
Andrew C. Hillier
We report grating-coupled surface plasmon resonance measurements involving the use of dispersion images to interpret the optical response of a metal-coated grating. Optical transmission through a grating coated with a thin, gold film exhibits features characteristic of the excitation of surface plasmon resonance due to coupling with the nanostructured grating surface. Evidence of numerous surface plasmon modes associated with coupling at both front (gold/air) and back (gold/substrate) grating interfaces is observed. The influence of wavelength and angle of incidence on plasmon coupling can be readily characterized via dispersion images, and the associated image features can be indexed to matching conditions …
Combined Electrochemical Surface Plasmon Resonance For Angle Spread Imaging Of Multielement Electrode Arrays, Andrew C. Hillier, Chang Hoon Choi
Combined Electrochemical Surface Plasmon Resonance For Angle Spread Imaging Of Multielement Electrode Arrays, Andrew C. Hillier, Chang Hoon Choi
Andrew C. Hillier
A surface plasmon resonance imaging system combined with a multielement electrode array is described. An optical system with shaping optics is used to direct a wedge of light onto a gold-coated sample. The reflected light is detected in the form of an angle-spread image of the surface, with one direction denoting a variable incident angle and the other showing a span of locations along one lateral direction of the sample surface. At the proper incident angle, the angle-spread image shows the complete surface plasmon resonance curve over a span of locations on the surface. This imaging system is combined with …
Surface Plasmon Resonance Enhanced Transmission Of Light Through Gold-Coated Diffraction Gratings, Bipin K. Singh, Andrew C. Hillier
Surface Plasmon Resonance Enhanced Transmission Of Light Through Gold-Coated Diffraction Gratings, Bipin K. Singh, Andrew C. Hillier
Andrew C. Hillier
Narrow peaks are observed in the transmission spectra of p-polarized light passing through a thin gold film that is coated on the surface of a transparent diffraction grating. The spectral position and intensity of these peaks can be tuned over a wide range of wavelengths by simple rotation of the grating. The wavelengths where these transmission peaks are observed correspond to conditions where surface plasmon resonance occurs at the gold−air interface. Light diffracted by the grating couples with surface plasmons in the metal film to satisfy the resonant condition, resulting in enhanced light transmission through the film. Notably, this phenomenon …
Mox/Cnts Hetero-Structures For Gas Sensing Applications: Role Of Cnts Defects, G. Neri, S. G. Leonardi, N. Donato, C. Marichy, Jean-Philippe Tessonnier, M.-G. Willinger, Kyeong-Hwan Lee, N. Pinna
Mox/Cnts Hetero-Structures For Gas Sensing Applications: Role Of Cnts Defects, G. Neri, S. G. Leonardi, N. Donato, C. Marichy, Jean-Philippe Tessonnier, M.-G. Willinger, Kyeong-Hwan Lee, N. Pinna
Jean-Philippe Tessonnier
The preparation, characterization and sensing properties of CNT composites with a thin metal oxide (MOx) surface layer is presented. Atomic layer deposition (ALD) was applied for the coating of the inner and outer CNTs walls with thin films of ZnO and SnO2 of precisely controlled thicknesses. Differently treated CNTs with different degree of surface functionalization were used as support for the oxide films. The sensing properties of the obtained composite materials towards NO2 were investigated and related to the morphological and microstructural characteristics of both the coating and support. SnO2-based composites on CNTs treated at 700 °C show enhanced performance …
Labeling And Monitoring The Distribution Of Anchoring Sites On Functionalized Cnts By Atomic Layer Deposition, Catherine Marichy, Jean-Philippe Tessonnier, Marta C. Ferro, Kyeong-Hwan Lee, Robert Schlogl, Nicola Pinna, Marc-Georg Willinger
Labeling And Monitoring The Distribution Of Anchoring Sites On Functionalized Cnts By Atomic Layer Deposition, Catherine Marichy, Jean-Philippe Tessonnier, Marta C. Ferro, Kyeong-Hwan Lee, Robert Schlogl, Nicola Pinna, Marc-Georg Willinger
Jean-Philippe Tessonnier
The chemical inertness of graphite and, in the case of tubes, of rolled up few layer graphene sheets, requires some degree of "defect engineering" for the fabrication of carbon based heterostructured materials. It is shown that atomic layer deposition provides a means to specifically label anchoring sites and can be used to characterize the surface functionality of differently treated carbon nanotubes. Direct observation of deposited titania by analytical transmission electron microscopy reveals the location and density of anchoring sites as well as structure related concentrations of functional groups on the surface of the tubes. Controlled functionalization of the tubes therefore …
Direct Pore‐Level Observation Of Permeability Increase In Two‐Phase Flow By Shaking, Igor A. Beresnev, William Gaul, R. Dennis Vigil
Direct Pore‐Level Observation Of Permeability Increase In Two‐Phase Flow By Shaking, Igor A. Beresnev, William Gaul, R. Dennis Vigil
R. Dennis Vigil
Increases in permeability of natural reservoirs and aquifers by passing seismic waves have been well documented. If the physical causes of this phenomenon can be understood, technological applications would be possible for controlling the flow in hydrologic systems or enhancing production from oil reservoirs. The explanation of the dynamically increased mobility of underground fluids must lie at the pore level. The natural fluids can be viewed as two-phase systems, composed of water as the wetting phase and of dispersed non-wetting globules of gas or organic fluids, flowing through tortuous constricted channels. Capillary forces prevent free motion of the suspended non-wetting …
Thickness Of Residual Wetting Film In Liquid-Liquid Displacement, Igor A. Beresnev, William Gaul, R .Dennis Vigil
Thickness Of Residual Wetting Film In Liquid-Liquid Displacement, Igor A. Beresnev, William Gaul, R .Dennis Vigil
R. Dennis Vigil
Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, …
Forced Instability Of Core-Annular Flow In Capillary Constrictions, Igor A. Beresnev, William Gaul, R. Dennis Vigil
Forced Instability Of Core-Annular Flow In Capillary Constrictions, Igor A. Beresnev, William Gaul, R. Dennis Vigil
R. Dennis Vigil
Instability of fluid cylinders and jets, a highly nonlinear hydrodynamic phenomenon, has fascinated researchers for nearly 150 years. A subset of the phenomenon is the core-annular flow, in which a non-wetting core fluid and a surrounding wall-wetting annulus flow through a solid channel. The model, for example, represents the flow of oil in petroleum reservoirs. The flow may be forced to break up when passing through a channel’s constriction. Although it has long been observed that the breakup occurs near the neck of the constriction, the exact conditions for the occurrence of the forced breakup and its dynamic theory have …
Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil
Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil
R. Dennis Vigil
The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of Np spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can be corrected by carrying out simulations using different simulation box sizes. Specifically, the diffusion coefficient is inversely proportional to the length of a cubic simulation box, and the constant of proportionality appears to be independent of …
Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler
Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler
Jennifer M. Heinen
Microemulsion polymerizations are attractive for investigating compartmentalization effects in heterogeneous reversible addition - fragmentation chain transfer (RAFT) polymerizations because the propagating radicals are segregated into surfactant stabilized polymer particles, which drastically reduces the effects of biradical termination, Also, microemulsion polymerizations do not involve the large monomer droplets that are present in emulsion and miniemulsion polymerizations. RAFT microemulsion polymerizations of butyl aery late with a high water solubility chain transfer agent, methyl-2-(O-ethylxanthyl)propionate (MOEP), and a low water solubility chain transfer agent, methyl-2-(O-dodecylxanthyl)propionate (MODP), were investigated to determine the effect of chain transfer agent compartmentalization on the control of the polymerization. The …
Influence Of The Graphitisation Of Hollow Carbon Nanofibers On Their Functionalisation And Subsequent Filling With Metal Nanoparticles, Jean-Philippe Tessonnier, Dirk Rosenthal, Frank Girgsdies, Julien Amadou, Dominique Begin, Cuong Pham-Huu, Dang Sheng Su, Robert Schlogl
Influence Of The Graphitisation Of Hollow Carbon Nanofibers On Their Functionalisation And Subsequent Filling With Metal Nanoparticles, Jean-Philippe Tessonnier, Dirk Rosenthal, Frank Girgsdies, Julien Amadou, Dominique Begin, Cuong Pham-Huu, Dang Sheng Su, Robert Schlogl
Jean-Philippe Tessonnier
The functionalisation of carbon nanomaterials with the standard nitric acid treatment is greatly influenced by their graphitic character. The structural order directs the density as well as the nature of the created functional groups and, as a consequence, influences the efficiency of their filling with metal nanoparticles.
Amino-Functionalized Carbon Nanotubes As Solid Basic Catalysts For The Transesterification Of Triglycerides, Alberto Villa, Jean-Philippe Tessonnier, Olivier Majoulet, Dang Shen Su, Robert Schlogl
Amino-Functionalized Carbon Nanotubes As Solid Basic Catalysts For The Transesterification Of Triglycerides, Alberto Villa, Jean-Philippe Tessonnier, Olivier Majoulet, Dang Shen Su, Robert Schlogl
Jean-Philippe Tessonnier
Multiwalled carbon nanotubes grafted with various amino groups show high activity and stability when used as basic catalysts for the transesterification of triglycerides.
Selective Deposition Of Metal Nanoparticles Inside Or Outside Multiwalled Carbon Nanotubes, Jean-Philippe Tessonnier, Ovidiu Ersen, Gisela Weinberg, Cuong Pham-Huu, Dang Sheng Su, Robert Schlogl
Selective Deposition Of Metal Nanoparticles Inside Or Outside Multiwalled Carbon Nanotubes, Jean-Philippe Tessonnier, Ovidiu Ersen, Gisela Weinberg, Cuong Pham-Huu, Dang Sheng Su, Robert Schlogl
Jean-Philippe Tessonnier
A general method is described for the deposition of metal nanoparticles selectively either inside or outside of carbon nanotubes (CNTs). The method is based on the difference in the interface energies of organic and aqueous solutions with the CNT surface. Because of their lipophilic character, the organic solvent better wets the surface of the nanotubes compared to water and penetrates into the inner volume. The precise control of the volume of each phase allows filling the CNT with the organic phase and covering its outer surface with the aqueous one. Hence, metal nanoparticles can be put with high selectivity either …
Dna Assembler, An In Vivo Genetic Method For Rapid Construction Of Biochemical Pathways, Zengyi Shao, Hua Zhao, Huimin Zhao
Dna Assembler, An In Vivo Genetic Method For Rapid Construction Of Biochemical Pathways, Zengyi Shao, Hua Zhao, Huimin Zhao
Zengyi Shao
The assembly of large recombinant DNA encoding a whole biochemical pathway or genome represents a significant challenge. Here, we report a new method, DNA assembler, which allows the assembly of an entire biochemical pathway in a single step via in vivo homologous recombination in Saccharomyces cerevisiae. We show that DNA assembler can rapidly assemble a functional d-xylose utilization pathway (∼9 kb DNA consisting of three genes), a functional zeaxanthin biosynthesis pathway (∼11 kb DNA consisting of five genes) and a functional combined d-xylose utilization and zeaxanthin biosynthesis pathway (∼19 kb consisting of eight genes) with high efficiencies (70 - 100%) …
An Explicit Method For The Packing Limit Management In Dense Gas-Solid Flow Cfd Simulations On Both Structured And Unstructured Grids, Alberto Passalacqua, Luca Marmo
An Explicit Method For The Packing Limit Management In Dense Gas-Solid Flow Cfd Simulations On Both Structured And Unstructured Grids, Alberto Passalacqua, Luca Marmo
Alberto Passalacqua
An explicit method for limiting the volume fraction of the dispersed phase in the CFD simulations of dense gas-solid flows is described and validated both on structured and unstructured computational grids. The procedure is based on the excess solids volume correction method proposed by Lettieri et al. (2003), which has been extended in this work to non-uniform grids made of cells having different shape and size. The method has been implemented in OpenFOAM and validated through the simulation of a fludised bed in which the superficial gas velocity has been reduced to a value close to zero.
Zsm-5 Coatings On β-Sic Monoliths: Possible New Structured Catalyst For The Methanol-To-Olefins Process, B. Madani, S. Ivanova, B. Louis, Jean-Philippe Tessonnier, M. J. Ledoux, C. Pham-Huu
Zsm-5 Coatings On β-Sic Monoliths: Possible New Structured Catalyst For The Methanol-To-Olefins Process, B. Madani, S. Ivanova, B. Louis, Jean-Philippe Tessonnier, M. J. Ledoux, C. Pham-Huu
Jean-Philippe Tessonnier
Structured zeolite/silicon carbide composites were succesfully synthesized by ZSM-5 coatings deposited on macroscopic â-SiC foams with medium surface area. A homogeneous coverage of the support (30 wt % zeolite) by ZSM-5 crystals, having 1 ím average size, was reached after a double-coating procedure. The ZSM-5/â-SiC composite materials were characterized by BET, XRD, SEM, and H/D exchange methods. 27Al MAS NMR analysis revealed that all aluminum was present in a tetrahedral coordination, thus sitting in the zeolite framework. The existence of a nanoscopic layer of silica and silicon oxycarbide on the surface of the support ensures the strong anchoring of the …
Quantitative Measurement Of The Brã¶Nsted Acid Sites In Solid Acids: Toward A Single-Site Design Of Mo-Modified Zsm-5 Zeolite, Jean-Philippe Tessonnier, Benoit Louis, Stephane Walspurger, Jean Sommer, Marc-Jacques Ledoux, Cuong Pham-Huu
Quantitative Measurement Of The Brã¶Nsted Acid Sites In Solid Acids: Toward A Single-Site Design Of Mo-Modified Zsm-5 Zeolite, Jean-Philippe Tessonnier, Benoit Louis, Stephane Walspurger, Jean Sommer, Marc-Jacques Ledoux, Cuong Pham-Huu
Jean-Philippe Tessonnier
On the basis of our previous H/D exchange studies devoted to the quantification of the number of Bro¨nsted acid sites in solid acids, we report here an innovative approach to determine both the amount and the localization of Mo atoms inside the Mo/ZSM-5 catalyst, commonly used for the methane dehydroaromatization reaction. The influence of Mo introduction in the MFI framework was studied by means of BET, X-ray diffraction, 27Al magic angle spinning NMR, NH3 temperature-programmed desorption, and H/D isotopic exchange techniques. A dependence was found between the decrease of acidic OH groups and the Mo content. Depending on the Si/Al …
Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh
Quantitative Elucidation Of A Distinct Spatial Gradient-Sensing Mechanism In Fibroblasts, Ian C. Schneider, Jason M. Haugh
Ian C. Schneider
Migration of eukaryotic cells toward a chemoattractant often relies on their ability to distinguish receptor-mediated signaling at different subcellular locations, a phenomenon known as spatial sensing. A prominent example that is seen during wound healing is fibroblast migration in platelet-derived growth factor (PDGF) gradients. As in the well-characterized chemotactic cells Dictyostelium discoideum and neutrophils, signaling to the cytoskeleton via the phosphoinositide 3-kinase pathway in fibroblasts is spatially polarized by a PDGF gradient; however, the sensitivity of this process and how it is regulated are unknown. Through a quantitative analysis of mathematical models and live cell total internal reflection fluorescence microscopy …
Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh
Spatial Analysis Of 3′ Phosphoinositide Signaling In Living Fibroblasts, Iii: Influence Of Cell Morphology And Morphological Polarity, Ian C. Schneider, Elizabeth M. Parrish, Jason M. Haugh
Ian C. Schneider
Activation of phosphoinositide (PI) 3-kinase is a required signaling pathway in fibroblast migration directed by platelet-derived growth factor. The pattern of 3′ PI lipids in the plasma membrane, integrating local Pl 3-kinase activity as well as 3′ PI diffusion and turnover, influences the spatiotemporal regulation of the cytoskeleton. In fibroblasts stimulated uniformly with platelet-derived growth factor, visualized using total internal reflection fluorescence microscopy, we consistently observed localized regions with significantly higher or lower 3′ PI levels than adjacent regions (hot and cold spots, respectively). A typical cell contained multiple hot spots, coinciding with apparent leading edge structures, and at most …