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Articles 1 - 14 of 14
Full-Text Articles in Engineering
Phosphate Salts Facilitate The Electrospinning Of Hyaluronic Acid Fiber Mats, Eric K. Brenner, Jessica D. Schiffman, Laura J. Toth, Janah C. Szewczyk, Caroline L. Schauer
Phosphate Salts Facilitate The Electrospinning Of Hyaluronic Acid Fiber Mats, Eric K. Brenner, Jessica D. Schiffman, Laura J. Toth, Janah C. Szewczyk, Caroline L. Schauer
Jessica D. Schiffman
Electrospinning is a cost effective and facile method to manufacture fiber mats appropriate for biomedical applications. Due to its high molecular weight and charged backbone, hyaluronic acid (HA) fiber mats with consistent fiber morphology have been difficult to electrospin from neutral pH solutions. Here, we present that the electrospinning of HA fibers in aqueous dimethylformamide solutions is facilitated by the addition of three phosphate salts. The salts—glycerol phosphate (GP), sodium phosphate (SP), and tripolyphosphate (TPP)—facilitated electrospinning of the solutions as characterized by conductivity measurements and fiber morphology. From tensile experiments, HA mats electrospun with SP demonstrated improved Young’s modulus (12 …
Crosslinking Poly(Allylamine) Fibers Electrospun From Basic And Acidic Solutions, Jessica D. Schiffman, Marjorie A. Kiechel, Amalie E. Donius, Ulrike G. K. Wegst, Caroline L. Schauer
Crosslinking Poly(Allylamine) Fibers Electrospun From Basic And Acidic Solutions, Jessica D. Schiffman, Marjorie A. Kiechel, Amalie E. Donius, Ulrike G. K. Wegst, Caroline L. Schauer
Jessica D. Schiffman
Mechanically robust, non-toxic polymer fiber mats are promising materials for a range of biomedical applications; however, further research into enhancing polymer selection is needed. In this study, poly(allylamine) (PAH), an amine-containing polyelectrolyte, was successfully electrospun from aqueous solutions into continuous, cylindrical fibers with a mean diameter of 150 ± 41 nm. A one-step crosslinking method using glutaraldehyde provides insight into the chemical and morphological changes that result from altering the molar ratio of amine to aldehyde groups, whereas a two-step crosslinking method yielded chemically and mechanically robust mats. These results indicate PAH fibrous mats synthesized from aqueous solutions could potentially …
Designing Electrospun Nanofiber Mats To Promote Wound Healing – A Review, Katrina A. Rieger, Nathan P. Birch, Jessica D. Schiffman
Designing Electrospun Nanofiber Mats To Promote Wound Healing – A Review, Katrina A. Rieger, Nathan P. Birch, Jessica D. Schiffman
Jessica D. Schiffman
Current strategies to treat chronic wounds offer limited relief to the 7.75 million patients who suffer from burns or chronic skin ulcers. Thus, as long as chronic wounds remain a global healthcare problem, the development of alternate treatments remain desperately needed. This review explores the recent strategies employed to tailor electrospun nanofiber mats towards accelerating the wound healing process. Porous nanofiber mats readily produced by the electrospinning process offer a promising solution to the management of wounds. The matrix chemistry, surface functionality, and mat degradation rate all can be fine-tuned to govern the interactions that occur at the materials–biology interface. …
Dynamic Metabolic Modeling Of A Microaerobic Yeast Co-Culture: Predicting And Optimizing Ethanol Production From Glucose/Xylose Mixtures, Timothy J. Hanly, Michael A. Henson
Dynamic Metabolic Modeling Of A Microaerobic Yeast Co-Culture: Predicting And Optimizing Ethanol Production From Glucose/Xylose Mixtures, Timothy J. Hanly, Michael A. Henson
Michael A Henson
Background: A key step in any process that converts lignocellulose to biofuels is the efficient fermentation of both hexose and pentose sugars. The co-culture of respiratory-deficient Saccharomyces cerevisiae and wild-type Scheffersomyces stipitis has been identified as a promising system for microaerobic ethanol production because S. cerevisiae only consumes glucose while S. stipitis efficiently converts xylose to ethanol. Results: To better predict how these two yeasts behave in batch co-culture and to optimize system performance, a dynamic flux balance model describing co-culture metabolism was developed from genome-scale metabolic reconstructions of the individual organisms. First a dynamic model was developed for each …
Wrinkling Of Inhomogeneously Strained Thin Polymer Films, Yu-Cheng Chen, Alfred Crosby
Wrinkling Of Inhomogeneously Strained Thin Polymer Films, Yu-Cheng Chen, Alfred Crosby
Alfred Crosby
Wrinkles occur due to a mechanical instability when sufficient strain is applied to an incompressible thin film attached to a deformable substrate. For wrinkles made with a polymer film supported on a soft elastomer, the amplitude is directly proportional to the wavelength and the square root of the applied strain. This dependence has been confirmed with ideal substrates where the global strain is homogeneously distributed, but the influence of strain inhomogeneity has not been considered previously. We use the contact line wrinkling technique to prepare polystyrene thin films with periodic regions of different wrinkle amplitudes, hence strains, on soft substrates. …
My Relations With Russian Polymer Science, Otto Vogl, Frank T. Traceski, Friderikh Diachekovski
My Relations With Russian Polymer Science, Otto Vogl, Frank T. Traceski, Friderikh Diachekovski
Otto Vogl
No abstract provided.
A Unified Perspective On Traffic Flow Theory. Part Iii: Validation And Benchmarking, Daiheng Ni, Haizhong Wang
A Unified Perspective On Traffic Flow Theory. Part Iii: Validation And Benchmarking, Daiheng Ni, Haizhong Wang
Daiheng Ni
Over more than half a century, traffic flow theorists have been pursuing two goals: (1) simple and efficient models to abstract vehicular traffic flow and (2) a unified framework in which existing traffic flow models fit and relate to each other. Continuing these efforts, we report our humble understanding in a trio of papers. The first paper (Part I) introduced a Field Theory with an emphasis on traffic flow modeling at the microscopic level. The second paper (Part II) uses the Field Theory as a framework to relate existing microscopic and macroscopic models to each other and summarizes the relations …
A Unified Perspective On Traffic Flow Theory. Part I: The Field Theory, Daiheng Ni
A Unified Perspective On Traffic Flow Theory. Part I: The Field Theory, Daiheng Ni
Daiheng Ni
Over more than half a century, traffic flow theorists have been pursuing two goals: (1) simple and efficient models to abstract vehicular traffic flow and (2) a unified framework in which existing traffic flow models fit and relate to each other. Continuing these efforts, we report our humble understanding in a trio of papers. This paper (Part I) introduces a Field Theory with an emphasis on traffic flow modeling at the microscopic level. In this theory, highways and vehicles are perceived as a field by a subject driver whose driving strategy is to navigate through the field along its valley. …
Direct Solution Of Current Density Induced On A Rough Surface By Forward Propagating Waves, Ramakrishna Janaswamy
Direct Solution Of Current Density Induced On A Rough Surface By Forward Propagating Waves, Ramakrishna Janaswamy
Ramakrishna Janaswamy
A new Volterra integral equation of the second kind with square integrable kernel is derived for paraxial propagation of radiowaves over a gently varying, perfectly conducting rough surface. The integral equation is solved exactly in terms of a infinite series and the necessary and sufficient conditions for the solution to exist and converge are established. Super exponential convergence of the Neumann series for arbitrary surface slope is established through asymptotic analysis. Expressions are derived for the determination of the number of terms needed to achieve a given accuracy, the latter depending on the parameters of the rough surface, the frequency …
Effect Of Voltage Polarity And Amplitude On Electroforming Of Tio2 Based Memristive Devices, Hao Jiang, Qiangfei Xia
Effect Of Voltage Polarity And Amplitude On Electroforming Of Tio2 Based Memristive Devices, Hao Jiang, Qiangfei Xia
Qiangfei Xia
Pt/TiO2/Pt/Ti memristive devices were electrically formed to either the ON or OFF state using voltages of the same polarity but with different amplitudes. The forming step dictated the subsequent switching behaviour. A qualitative model based on the creation and migration of oxygen vacancies was proposed to explain the experimental results.
Effect Of Voltage Polarity And Amplitude On Electroforming Of Tio2 Based Memristive Devices, Hao Jiang, Qiangfei Xia
Effect Of Voltage Polarity And Amplitude On Electroforming Of Tio2 Based Memristive Devices, Hao Jiang, Qiangfei Xia
Qiangfei Xia
Pt/TiO2/Pt/Ti memristive devices were electrically formed to either the ON or OFF state using voltages of the same polarity but with different amplitudes. The forming step dictated the subsequent switching behaviour. A qualitative model based on the creation and migration of oxygen vacancies was proposed to explain the experimental results.
Cross Point Arrays Of 8 Nm × 8 Nm Memristive Devices Fabricated With Nanoimprint Lithography, Shuang Pi, Peng Lin, Qiangfei Xia
Cross Point Arrays Of 8 Nm × 8 Nm Memristive Devices Fabricated With Nanoimprint Lithography, Shuang Pi, Peng Lin, Qiangfei Xia
Qiangfei Xia
Building arrays of memristive devices with sub-10 nm lateral dimensions is critical for high packing density, low power consumption, and better uniformity in device performance. Here, the authors demonstrate arrays of 8 × 8 nm2 cross point memristive devices using wet chemical etching and nanoimprint lithography. The devices exhibited nonvolatile bipolar switching with extreme low programming current of 600 pA. The devices also exhibited fast switching speed and improved uniformity and promising endurance and data retention. This work opens the opportunities for memristive devices in the next generation ultrahigh-density data storage and low-power high-speed unconventional computing.
Low Voltage Resistive Switching Devices Based On Chemically Produced Silicon Oxide, Can Li, Hao Jiang, Qiangfei Xia
Low Voltage Resistive Switching Devices Based On Chemically Produced Silicon Oxide, Can Li, Hao Jiang, Qiangfei Xia
Qiangfei Xia
We developed nonvolatile metal/SiOx/Si memristive devices based on ultrathin (∼1 nm) silicon oxide that was produced in a Piranha solution. The devices exhibited repeatable resistive switching behavior with low programming voltages (as low as 0.5 V) and high ON/OFF conductance ratio. Devices with active metals as top electrodes were bipolar switches, while those with inert metal electrodes were unipolar. We also studied the switching mechanisms for both types of devices based on the filament formation and rupture, and proposed conduction models for Pt/SiOx/Si devices.
Mold Cleaning With Polydimethylsiloxane (Pdms) For Nanoimprint Lithography, Peng Lin, Shuang Pi, Jiang Jiang, Qiangfei Xia
Mold Cleaning With Polydimethylsiloxane (Pdms) For Nanoimprint Lithography, Peng Lin, Shuang Pi, Jiang Jiang, Qiangfei Xia
Qiangfei Xia
We present a simple and effective mold cleaning method for nanoimprint lithography. Polydimethylsiloxane (PDMS) prepolymer is spin-coated onto a contaminated imprint mold, thermally cured in an ambient environment, and then peeled off afterwards. Contaminants of 100 s μm to sub-50 nm sizes are effectively cleaned within one cycle. During the cleaning process, a very thin PDMS film (1–2 nm) is uniformly coated onto the mold surface, serving as a protection and anti-sticking layer.