1,654 research outputs found

    The application of active controls technology to a generic hypersonic aircraft configuration

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    Analytical methods are described for the prediction of aerothermoelastic stability of hypersonic aircraft including active control systems. Thermal loads due to aerodynamic heating were applied to the finite element model of the aircraft structure and the thermal effects on flutter were determined. An iterative static aeroelastic trim analysis procedure was developed including thermal effects. And active control technology was assessed for flutter suppression, ride quality improvement, and gust load alleviation to overcome any potential adverse aeroelastic stability or response problems due to aerodynamic heating. A generic hypersonic aircraft configuration was selected which incorporates wing flaps, ailerons, and all moveable fins to be used for active control purposes. The active control system would use onboard sensors in a feedback loop through the aircraft flight control computers to move the surfaces for improved structural dynamic response as the aircraft encounters atmospheric turbulence

    Medium-chain fatty acids released from polymeric electrospun patches inhibit Candida albicans growth and reduce the biofilm viability

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    Oral candidiasis is a very common oral condition among susceptible individuals, with the main causative organism being the fungus Candida albicans. Current drug delivery systems to the oral mucosa are often ineffective because of short drug/tissue contact times as well as increased prevalence of drug-resistant Candida strains. We evaluated the potency of saturated fatty acids as antifungal agents and investigated their delivery by novel electrospun mucoadhesive oral patches using agar disk diffusion and biofilm assays. Octanoic (C8) and nonanoic (C9) acids were the most effective at inhibiting C. albicans growth on disk diffusion assays, both in solution or when released from polycaprolactone (PCL) or polyvinylpyrrolidone/RS100 (PVP/RS100) electrospun patches. In contrast, dodecanoic acid (C12) displayed the most potent antifungal activity against pre-existing C. albicans biofilms in solution or when released by PCL or PVP/RS100 patches. Both free and patch-released saturated fatty acids displayed a significant toxicity to wild-type and azole-resistant strains of C. albicans. These data not only provide evidence that certain saturated fatty acids have the potential to be used as antifungal agents but also demonstrate that this therapy could be delivered directly to Candida-infected sites using electrospun mucoadhesive patches, demonstrating a potential new therapeutic approach to treat oral thrush

    Enhanced uptake of nanoparticle drug carriers via a thermoresponsive shell enhances cytotoxicity in a cancer cell line

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    Polymer particles consisting of a biodegradable poly[lactide-co-glycolide] (PLGA) core and a thermoresponsive shell have been formulated to encapsulate the dye rhodamine 6G and the potent cytotoxic drug paclitaxel. Cellular uptake of these particles is significantly enhanced above the thermal transition temperature (TTT) of the polymer shells in the human breast carcinoma cell line MCF-7 as determined by flow cytometry and fluorescence microscopy. Paclitaxel-loaded particles display reduced and enhanced cytotoxicity below and above the TTT respectively compared to unencapsulated drug. The data suggests a potential route to enhanced anti-cancer efficacy through temperature-mediated cell targeting.© The Royal Society of Chemistry 2013

    Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania

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    BACKGROUND: Streptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change. METHODS: We evaluated 602 cases of IPD reported in Philadelphia County, Pennsylvania, from 2002 to 2007. Poisson regression models incorporating seasonal smoothers were used to identify associations between weekly weather patterns and case counts. Associations between acute (dayto- day) environmental fluctuations and IPD occurrence were evaluated using a case-crossover approach. Effect modification across age and sex strata was explored, and meta-regression models were created using stratum-specific estimates for effect. RESULTS: IPD incidence was greatest in the wintertime, and spectral decomposition revealed a peak at 51.0 weeks, consistent with annual periodicity. After adjustment for seasonality, yearly increases in reporting, and temperature, weekly incidence was found to be associated with clear-sky UV index (IRR per unit increase in index: 0.70 [95% CI 0.54-0.91]). The effect of UV index was highest among young strata and decreased with age. At shorter time scales, only an association with increases in ambient sulphur oxides was linked to disease risk (OR for highest tertile of exposure 0.75, 95% CI 0.60 to 0.93). CONCLUSION: We confirmed the wintertime predominance of IPD in a major urban center. The major predictor of IPD in Philadelphia is extended periods of low UV radiation, which may explain observed wintertime seasonality. The mechanism of action of diminished light exposure on disease occurrence may be due to direct effects on pathogen survival or host immune function via altered 1,25-(OH)2-vitamin-D metabolism. These findings may suggest less diminution in future IPD risk with climate change than would be expected if wintertime seasonality was driven by temperature

    Carbon monoxide measurements at Mace Head, Ireland

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    The North Atlantic Ocean is bordered by continents which may each, under the influence of seasonal weather patterns, act as sources of natural and anthropogenic trace gas and particulate species. Photochemically active species such as carbon monoxide (CO) react to form ozone (O3), a species of critical importance in global climate change. CO is sparingly soluble in water, and the relatively long lifetime of CO in the troposphere makes this species an ideal tracer of air masses with origin over land. We have measured CO using a nondispersive infrared gas filter correlation analyzer at Mace Head on the west coast of Ireland nearly continuously since August 9, 1991. Measurements of CO were acquired at 20-sec resolution and recorded as 60-sec averages. Daily, monthly, and diurnal variation data characteristics of CO mixing ratios observed at this site are reported. Depending on source regions of air parcels passing over this site, 60-min concentrations of CO range from clean air values of approximately 90 ppbv to values in excess of 300 ppbv. Data characterizing the correlation between 60-min CO and O3 mixing ratio data observed at this site are reported also

    Mucoadhesive electrospun patch delivery of lidocaine to the oral mucosa and investigation of spatial distribution in tissue using MALDI-mass spectrometry imaging

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    Many oral mucosal conditions cause considerable and prolonged pain that to date has been difficult to alleviate via topical delivery, and the use of injection causes many patients dental anxiety and needle-prick pain. Therefore, developing a non-injectable drug delivery system as an alternative administration procedure may vastly improve the health and wellbeing of these patients. Recent advances in the development of mucoadhesive electrospun patches for the direct delivery of therapeutics to the oral mucosa offer a potential solution, but as yet, the release of local anaesthetics from this system and their uptake by oral tissue has not been demonstrated. Here, we demonstrate the fabrication of lidocaine-loaded electrospun fibre patches, drug release, and subsequent uptake and permeation through porcine buccal mucosa. Lidocaine HCl and lidocaine base were incorporated into the electrospun patches to evaluate the difference in drug permeation for the two drug compositions. Lidocaine released from the lidocaine HCl-containing electrospun patches was significantly quicker than from the lidocaine base patches, with double the amount of drug released from the lidocaine HCl patches in the first 15 minutes (0.16 ± 0.04 mg) compared to from the lidocaine base patches (0.07 ± 0.01 mg). The permeation of lidocaine from the lidocaine HCl electrospun patches through ex vivo porcine buccal mucosa was also detected in 15 minutes, whereas permeation of lidocaine from the lidocaine base patch was not detected. Matrix-assisted laser desorption ionisation – mass spectrometry imaging (MALDI-MSI) was used to investigate localisation of lidocaine within oral tissue. Lidocaine in solution as well as from the mucoadhesive patch penetrated into buccal mucosal tissue in a time-dependent manner and was detectable in the lamina propria after only 15 minutes. Moreover, the lidocaine released from lidocaine HCl electrospun patches retained biological activity, inhibiting veratridine-mediated opening of voltage-gated sodium channels in SH-SY5Y neuroblastoma cells. These data suggest that a mucoadhesive electrospun patch may be used as a vehicle for rapid uptake and sustained anaesthetic drug delivery and may reduce the need for injection

    Finite temperature bosonization

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    Finite temperature properties of a non-Fermi liquid system is one of the most challenging probelms in current understanding of strongly correlated electron systems. The paradigmatic arena for studying non-Fermi liquids is in one dimension, where the concept of a Luttinger liquid has arisen. The existence of a critical point at zero temperature in one dimensional systems, and the fact that experiments are all undertaken at finite temperature, implies a need for these one dimensional systems to be examined at finite temperature. Accordingly, we extended the well-known bosonization method of one dimensional electron systems to finite temperatures. We have used this new bosonization method to calculate finite temperature asymptotic correlation functions for linear fermions, the Tomonaga-Luttinger model, and the Hubbard model.Comment: REVTex, 48 page

    Compressibility of CeMIn5Ce M In_5 and Ce2MIn8Ce_2 M In_8 (M = Rh, Ir and Co) Compounds

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    The lattice parameters of the tetragonal compounds CeMMIn5_{5} and Ce2M_{2}MIn8_{8}(M=M=Rh, Ir and Co) have been studied as a function of pressure up to 15 GPa using a diamond anvil cell under both hydrostatic and quasihydrostatic conditions at room temperature. The addition of MMIn2_{2} layers to the parent CeIn3_{3} compound is found to stiffen the lattice as the 2-layer systems (average of bulk modulus values B0B_{0} is 70.4 GPa) have a larger B0B_{0} than CeIn3_{3} (67 GPa), while the 1-layer systems with the are even stiffer (average of B0B_{0} is 81.4 GPa). Estimating the hybridization using parameters from tight binding calculations shows that the dominant hybridization is fpfp in nature between the Ce and In atoms. The values of VpfV_{pf} at the pressure where the superconducting transition temperature TcT_{c} reaches a maximum is the same for all CeMMIn5_{5} compounds. By plotting the maximum values of the superconducting transition temperature TcT_{c} versus c/ac/a for the studied compounds and Pu-based superconductors, we find a universal TcT_{c} versus c/ac/a behavior when these quantities are normalized appropriately. These results are consistent with magnetically mediated superconductivity.Comment: Updated version resubmitted to Phys. Rev.
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