13,983 research outputs found

    Polyimide from bis(n-isoprenyl)s of aryl diamides

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    A process and polyimide product formed by the reaction of a bismaleimide with a bis(amidediene) is disclosed wherein the bis(amidediene) is formed by reacting an excess of an acid chloride with 1,4-N,N'-diisoprenyl 2,3,5,6-tetramethy1 benzene

    Structured Codes Improve the Bennett-Brassard-84 Quantum Key Rate

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    A central goal in information theory and cryptography is finding simple characterizations of optimal communication rates under various restrictions and security requirements. Ideally, the optimal key rate for a quantum key distribution (QKD) protocol would be given by a single-letter formula involving optimization over a single use of an effective channel. We explore the possibility of such a formula for the simplest and most widely used QKD protocol, Bennnett-Brassard-84 with one-way classical postprocessing. We show that a conjectured single-letter formula is false, uncovering a deep ignorance about good private codes and exposing unfortunate complications in the theory of QKD. These complications are not without benefit—with added complexity comes better key rates than previously thought possible. The threshold for secure key generation improves from a bit error rate of 0.124 to 0.129

    DEVELOPMENT OF A CELL MORPHOLOGICAL ANALYSIS TOOL TO EVALUATE THE ULTRASOUND VIBRATIONAL EFFECTS ON CELL ADHESION

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    Fibroblast encapsulation is a stage of the wound healing process in which the implanted device is separated from the biological environment due to the formation of fibrotic tissue. Uncontrolled adhesion of fibroblasts, called fibrosis, has the ability to inhibit an implanted device’s functionality over its lifetime. Over time, fibroblasts have been shown to cause loosening and failure of bone-anchor implants which could include the possibility of harming the patient. The encapsulating process could also hinder the sensitivity of implanted biosensors operating in the body for continuous monitoring. Unfortunately, the antifouling surfaces which are commonly used on implanted devices to control the fibrotic response are not able to maintain their efficiency over an extended period of time and have a possibility to disrupt the device’s functionality. This project presents the development of a cell morphology analysis tool and an in vitro ultrasound system to investigate the effect of ultrasound on cell adhesion with the possibility of leading to further work in the control of fibroblast adhesion and prolonging the function and life of the implanted devices

    Preparation of bis(4-(3,4 dimethylene pyrrolidyl) phenyl) methane as a high temperature reactive oligomer

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    A major goal in the field of high temperature polymers was to prepare aromatic polyimides that can be easily fabricated with the required thermal and physical properties for aerospace applications. Recent research was directed to achieve polyimides that are: soluable in a common organic solvent; melt-processable; and thermally curable without the evolution of volatile by-products. A monomer, N-phenyl 3,4-dimethylene pyrrolidine, that can be modified to form a bis (exocyclodiene) I for the preparation of polyimides by the Diels-Alder process was developed. Preparation of high temperature polymeric materials by Diels-Alder polymerization that will maintain their integrity and toughness during long exposure time at elevated temperature is sought

    THE TAXONOMIC STATUS OF THE WYOMING TOAD, BUFO BAXTERI PORTER

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    The population of toads in southeastern Wyoming named Bufo hemiophrys baxteri by Porter in 1968 is presumed to be extinct in nature, except perhaps for released, captive-bred specimens. It is sufficiently distinct in several respects, and sufficiently isolated geographically from its nearest rela- tive, B. h. hemiophrys, that it should be regarded as a distinct species, forming a superspecies group with B. hemiophrys

    Incorporation of Functionalized Polyhedral Oligomeric Silsesquioxane Nanomaterials as Reinforcing Agents for Impact Ice Mitigating Coatings

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    In-flight, aircraft are exposed to a wide range of environments. One commonly exposed environment are clouds containing super-cooled water droplets. These water drop- lets exist in a metastable state below the freezing point of water, in the range of 0 to -20C. As the vehicle impacts the droplets, latent heat is released and within milliseconds the droplets convert to ice. This process is referred to as impact icing or in-flight icing.1 Impact icing is a major concern for aircraft since it can lead to degraded aerodynamic performance and, if left un- treated, can lead to loss of the vehicle. Active approaches (i.e., pneumatic boots, heated air ducts) typically utilized in mitigating in-flight ice accretion significantly increases vehicle weight and cannot be applied to all aircraft.1-3 A passive approach based on coatings is desired, but durability issues are a concern, especially on the wing leading edge.3 Nanomaterials have been shown to afford significant improvement in coating and composite physical properties at low loading levels.4 In this study, Polyhedral Oligomeric Silsesquioxane (POSS) nanomaterials have been shown to increase coating durability. Also, with wide variety of functionalities present on the arm structure, POSS nanomaterials have been shown to readily alter coating surface chemistry to mitigate impact ice adhesion from -16 to -8C in a simulated in-flight icing environment

    Computation of aircraft component flow fields at transonic Mach numbers using a three-dimensional Navier-Stokes algorithm

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    A computer analysis was developed for calculating steady (or unsteady) three-dimensional aircraft component flow fields. This algorithm, called ENS3D, can compute the flow field for the following configurations: diffuser duct/thrust nozzle, isolated wing, isolated fuselage, wing/fuselage with or without integrated inlet and exhaust, nacelle/inlet, nacelle (fuselage) afterbody/exhaust jet, complete transport engine installation, and multicomponent configurations using zonal grid generation technique. Solutions can be obtained for subsonic, transonic, or hypersonic freestream speeds. The algorithm can solve either the Euler equations for inviscid flow, the thin shear layer Navier-Stokes equations for viscous flow, or the full Navier-Stokes equations for viscous flow. The flow field solution is determined on a body-fitted computational grid. A fully-implicit alternating direction implicit method is employed for the solution of the finite difference equations. For viscous computations, either a two layer eddy-viscosity turbulence model or the k-epsilon two equation transport model can be used to achieve mathematical closure

    Consent to Surgery

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    The legal aspects of a patient\u27s consent to operation, or the lack of such consent, are many and varied. The general rule is that consent of the patient, or of someone authorized to act for him, is necessary in order for a physician to legally operate. This rule is not altered by the fact that an unauthorized operation is slight and ordinarily is not accompanied by serious consequences. Where no consent is present, a surgical operation upon the body is a technical battery, and in the absence of exceptional circumstances, appropriate damages may be recovered from the physician. The question as to whether consent, either either express or implied, has been given, is one of fact for the jury
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