Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Graphene Quantum Dots Electrochemistry and Sensitive Electrocatalytic Glucose Sensor Development

Abstract: Graphene quantum dots (GQDs), derived from functionalized graphene precursors are graphene sheets a few nanometers in the lateral dimension having a several-layer thickness. They are zero-dimensional materials with quantum confinement and edge site effects. Intense research interest in GQDs is attributed to their unique physicochemical phenomena arising from the sp2-bonded carbon nanocore surrounded with edged plane functional moieties. In this work, GQDs are synthesized by both solvothermal and hydrothermal techniques, with the optimal size of 5 nm determined using high-resolution transmission electron microscopy, with additional UV-Vis absorption and fluorescence spectroscopy, revealing electronic band signatures in the blue-violet region. Their potential in fundamental (direct electron transfer) and applied (enzyme-based glucose biosensor) electrochemistry has been practically realized. Glucose oxidase (GOx) was immobilized on glassy carbon (GC) electrodes modified with GQDs and functionalized graphene (graphene oxide and reduced form). The cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy are used for characterizing the direct electron transfer kinetics and electrocatalytical biosensing. The well-defined quasi-reversible redox peaks were observed under various electrochemical environment and conditions (pH, concentration, scan rate) to determine the diffusion coefficient (D) and first-order electron transfer rate (kET). The cyclic voltammetry curves showed homogeneous ion transport behavior for GQD and other graphene-based samples with D ranging between 8.45 × 10−9 m2 s−1 and 3 × 10−8 m2 s−1 following the order of GO < rGO < GQD < GQD (with FcMeOH as redox probe) < GOx/rGO < GOx/GO < HRP/GQDs < GOx/GQDs. The developed GOx-GQDs biosensor responds efficiently and linearly to the presence of glucose over concentrations ranging between 10 μM and 3 mM with a limit of detection of 1.35 μM and sensitivity of 0.00769 μA μM−1·cm−2 as compared with rGO (0.025 μA μM−1 cm−2, 4.16 μM) and GO (0.064 μA μM−1 cm−2, 4.82 μM) nanosheets. The relatively high performance and stability of GQDs is attributed to a sufficiently large surface-to-volume ratio, excellent biocompatibility, abundant hydrophilic edges, and a partially hydrophobic plane that favors GOx adsorption on the electrode surface and versatile architectures to ensure rapid charge transfer and electron/ion conduction (<10 ms). We also carried out similar studies with other enzymatic protein biomolecules on electrode surfaces prepared from GQD precursors for electrochemical comparison, thus opening up potential sensing applications in medicine as well as bio-nanotechnology.

Colonoscopy without sedation

Abstract: PURPOSE AND METHODS: Two hundred fifty-eight consecutive nonsedated colonoscopies were prospectively evaluated over an 18-month period The cecum was intubated in 250 cases (97 percent) Polypectomies or biopsies were performed in 77 cases (31 percent) Indications for colonoscopy included history of polyps (32 percent), hematochezia (28 percent), family history of colon cancer (16 percent), prior history of colon cancer (9 percent), change in bowel habits (12 percent), abnormal flexible sigmoidoscopy (6 percent), and inflammatory bowel disease (3 percent) RESULTS: Sedation was withheld for the following reasons: patient preference (57 percent), medical problems (2 percent), prior resection (16 percent), surgeon preference (65 percent), lack of intravenous access (3 percent), and age (1 percent) Three patients (15 percent) required sedation to complete the procedure Procedure-related pain was based on a scale from zero to three One hundred thirtynine patients (61 percent) rated their pain as either zero (no pain) or one (mild pain), and 217 percent (8 percent) indicated that they would prefer their next colonoscopy to be performed without sedation One hundred twelve patients had previously undergone sedated colonoscopy Ninety-two (92 percent) preferred nonsedated to sedated procedures Average procedure time was 137 (range, 05 to 85) minutes CONCLUSIONS: Several series have studied nonsedated endoscopic upper and lower gastrointestinal evaluations None, however, have evaluated patient comfort and satisfaction In our prospective series of 258 consecutive nonsedated colonoscopies, we found the procedure to be safe, effective, and well accepted

Analysis of the effect of interfacial roughness on fiber debonding and sliding in brittle matrix composites

Abstract: Previous analyses of the relation between the force and displacement during fiber sliding (pushing or pulling) are extended to include effects of interfacial roughness. Analytical solutions are obtained for a linear roughness profile over the range of displacements that are smaller than the dominant half-wavelength of the roughness. With the equations expressed in normalized form, a convenient friction parameter, which defines the roles of the friction coefficient and the roughness angle, has been defined. For certain values of the friction parameter, the effect of the roughness negates the Poisson's contraction during fiber pulling, giving solutions that are very close to the response of a system with a constant frictional stress at the interface.

Outcomes following single-treatment Gamma Knife surgery for trigeminal neuralgia with a minimum 3-year follow-up.

Abstract: Object Gamma Knife surgery (GKS) has been shown to be effective in treating trigeminal neuralgia (TN). Existing studies have demonstrated success rates of 69.1–85% with median follow-up intervals of 19–60 months. However, series with uniform long-term follow-up data for all patients have been lacking. In the present study the authors examined outcomes in a series of patients with TN who underwent a single GKS treatment followed by a minimum follow-up of 36 months. They used a clinical scale that simplifies the reporting of outcome data for patients with TN. Methods Fifty-three consecutive patients with typical, intractable TN received a median maximum radiation dose of 80 Gy applied with a single 4-mm isocenter to the affected trigeminal nerve. Follow-up data were obtained by clinical examination and questionnaire. Outcome results were categorized into the following classes (in order of decreasing success): Class 1A, complete pain relief without medications; 1B, complete pain relief with either a decrease...

Entropy Based Design and Analysis of Fluids Engineering Systems

Abstract: Introduction Introduction Governing Equations of Fluid Flow and Heat Transfer Mathematical Properties of Entropy and Exergy Governing Equations of Entropy and the Second Law Formulation of Entropy Production and Exergy Destruction Statistical and Numerical Formulations of the Second Law Introduction Conservation Laws as Moments of the Boltzmann Equation Extended Probability Distributions Selected Multivariate Probability Distribution Functions Concave Entropy Functions Statistical Formulation of the Second Law Numerical Formulation of the Second Law Predicted Irreversibilities of Incompressible Flows Introduction Entropy Transport Equation for Incompressible Flows Formulation of Loss Coefficients with Entropy Production Upper Entropy Bounds in Closed Systems Case Study of Automotive Fuel Cell Design Case Study of Fluid Machinery Design Measured Irreversibilities of Incompressible Flows Introduction Experimental Techniques of Irreversibility Measurement Case Study of Magnetic Stirring Tank Design Case Study of Natural Convection in Cavities Measurement Uncertainties Entropy Production in Microfluidic Systems Introduction Pressure-Driven Flow in Microchannels Applied Electric Field in Microchannels Micropatterned Surfaces with Open Microchannels Numerical Error Indicators and the Second Law Introduction Discretization Errors of Numerical Convection Schemes Physical Plausibility of Numerical Results Entropy Difference in Residual Error Indicators Numerical Stability and the Second Law Introduction Stability Norms Entropy Stability of Finite Difference Schemes Stability of Shock Capturing Methods Entropy Transport with Phase Change Heat Transfer Introduction Entropy Transport Equations for Solidification and Melting Heat and Entropy Analogies in Phase Change Processes Numerical Stability of Phase Change Computations Thermal Control of Phase Change with Inverse Methods Entropy Production with Film Condensation Entropy Production in Turbulent Flows Introduction Reynolds Averaged Entropy Transport Equations Eddy Viscosity Models of Mean Entropy Production Turbulence Modeling with the Second Law