2,268 research outputs found

    Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

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    This paper establishes a relationship between the polishing process parameters and the generation of mid spatial-frequency error. The consideration of the polishing lap design to optimize the process in order to keep residual errors to a minimum and optimization of the process (speeds, stroke, etc.) and to keep the residual mid spatial-frequency error to a minimum, is also presented

    Molecular signature of organic nitrogen in septic-impacted groundwater

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    Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Royal Society of Chemistry for personal use, not for redistribution. The definitive version was published in Environmental Science: Processes & Impacts 16 (2014):2400-2407, doi:10.1039/C4EM00289J.Dissolved inorganic and organic nitrogen levels are elevated in aquatic systems due to anthropogenic activities. Dissolved organic nitrogen (DON) arises from various sources, and its impact could be more clearly constrained if specific sources were identified and if the molecular level composition of DON were better understood. In this work, the pharmaceutical carbamazepine was used to identify septic-impacted groundwater in a coastal watershed. Using ultrahigh resolution mass spectrometry data, the nitrogen-containing features of the dissolved organic matter in septic-impacted and non-impacted samples were compared. The septic impacted groundwater samples have a larger abundance of nitrogen-containing formulas. Impacted samples have additional DON features in the regions ascribed as ‘protein-like’ and ‘lipid-like’ in van Krevelen space and have more intense nitrogen-containing features in a specific region of a carbon versus mass plot. These features are potential indicators of dissolved organic nitrogen arising from septic effluents, and this work suggests that ultrahigh resolution mass spectrometry is a valuable tool to identify and characterize sources of DON.The Deep Ocean Exploration and Coastal Ocean Institutes at WHOI and the University of Minnesota Institute on the Environment are thanked for financial support.2015-02-0

    Apparent Role for \u3cem\u3eBorrelia burgdorferi\u3c/em\u3e LuxS During Mammalian Infection

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    The Lyme disease spirochete, Borrelia burgdorferi, controls protein expression patterns during its tick-mammal infection cycle. Earlier studies demonstrated that B. burgdorferi synthesizes 4,5-dihydroxy-2,3-pentanedione (autoinducer-2 [AI-2]) and responds to AI-2 by measurably changing production of several infection-associated proteins. luxS mutants, which are unable to produce AI-2, exhibit altered production of several proteins. B. burgdorferi cannot utilize the other product of LuxS, homocysteine, indicating that phenotypes of luxS mutants are not due to the absence of that molecule. Although a previous study found that a luxS mutant was capable of infecting mice, a critical caveat to those results is that bacterial loads were not quantified. To more precisely determine whether LuxS serves a role in mammalian infection, mice were simultaneously inoculated with congenic wild-type and luxS strains, and bacterial numbers were assessed using quantitative PCR. The wild-type bacteria substantially outcompeted the mutants, suggesting that LuxS performs a significant function during mammalian infection. These data also provide further evidence that nonquantitative infection studies do not necessarily provide conclusive results and that regulatory factors may not make all-or-none, black-or-white contributions to infectivity

    Order out of Randomness : Self-Organization Processes in Astrophysics

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    Self-organization is a property of dissipative nonlinear processes that are governed by an internal driver and a positive feedback mechanism, which creates regular geometric and/or temporal patterns and decreases the entropy, in contrast to random processes. Here we investigate for the first time a comprehensive number of 16 self-organization processes that operate in planetary physics, solar physics, stellar physics, galactic physics, and cosmology. Self-organizing systems create spontaneous {\sl order out of chaos}, during the evolution from an initially disordered system to an ordered stationary system, via quasi-periodic limit-cycle dynamics, harmonic mechanical resonances, or gyromagnetic resonances. The internal driver can be gravity, rotation, thermal pressure, or acceleration of nonthermal particles, while the positive feedback mechanism is often an instability, such as the magneto-rotational instability, the Rayleigh-B\'enard convection instability, turbulence, vortex attraction, magnetic reconnection, plasma condensation, or loss-cone instability. Physical models of astrophysical self-organization processes involve hydrodynamic, MHD, and N-body formulations of Lotka-Volterra equation systems.Comment: 61 pages, 38 Figure

    Development of Biodegradable Food Packaging Materials from Agricultural Biomass

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    This study utilised maize husk fibres and pulp to prepare a biocomposite fabric for foodpackaging. The optimum conditions for extracting maize husk fibres were determinedexperimentally to be 5 g/l of sodium hydroxide concentration at 100 °C for 60 minutes and liquor ratio of 1:20. The fabric was manufactured by solution casting of maize husk pulp on a web prepared by aligning maize husk and sisal fibres using a deckle and frame. The sisal fibre content was varied from 5 to 50% at ratios ranging from 95:5 to 50:50 (maize: sisal fibres). The biodegradable fabric was characterised using three mechanical properties: tear strength, tensile strength, and abrasion resistance. The tear strength ranged from 0.79 MPa to 3.93 MPa whereas the tensile strength ranged from 13.35 MPa to 56.46 MPa, which conforms to the data available from literature. Abrasion tests verified that there was no mass loss at 5,000, 10,000 and 15,000 cycles. Overall, the study findings show that maize husk fibres can replace up to 80% of sisalfibres in materials for food packaging applications without compromising their quality. Keywords: Maize husk fibre, biocomposite, sisal fibres, food packaging

    BMQ

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    BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals

    Effect of Microscopic Damage Events on Static and Ballistic Impact Strength of Triaxial Braid Composites

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    The reliability of impact simulations for aircraft components made with triaxial-braided carbon-fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Methods to characterize the material properties used in the analytical models from a systematically obtained set of test data are also lacking. A macroscopic finite element based analytical model to analyze the impact response of these materials has been developed. The stiffness and strength properties utilized in the material model are obtained from a set of quasi-static in-plane tension, compression and shear coupon level tests. Full-field optical strain measurement techniques are applied in the testing, and the results are used to help in characterizing the model. The unit cell of the braided composite is modeled as a series of shell elements, where each element is modeled as a laminated composite. The braided architecture can thus be approximated within the analytical model. The transient dynamic finite element code LS-DYNA is utilized to conduct the finite element simulations, and an internal LS-DYNA constitutive model is utilized in the analysis. Methods to obtain the stiffness and strength properties required by the constitutive model from the available test data are developed. Simulations of quasi-static coupon tests and impact tests of a represented braided composite are conducted. Overall, the developed method shows promise, but improvements that are needed in test and analysis methods for better predictive capability are examined

    Impact of a single oral dose of 100,000 IU vitamin D3 on profiles of serum 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 in adults with vitamin D insufficiency

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    We investigate the effect of a high dose of vitamin D3 on circulating concentrations of 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 in healthy individuals with self-perceived fatigue and vitamin D insufficiency (25(OH)D3 75 nmol/L. Among individuals who receivedvitamin D3, there were significant increases in serum concentrations of25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and1,25(OH)2D3 at 4 weeks; however, inter-individual variability inthese changes was substantial. Positive correlations between serum 25(OH)D3 and24,25(OH)2D3 and 3-epi-25(OH)D3, and a significant negativecorrelation between serum 1,25(OH)2D3 and 3-epi-25(OH)D3, were found4 weeks after supplementation. The 24,25(OH)2D3/25(OH)D3 and24,25(OH)2D3/1,25(OH)2D3 ratios were significantly increased,compared with baseline, in participants receiving vitamin D3. Baseline 25(OH)D3concentration was the only factor predictive of the change in 25(OH)D3 aftersupplementation.  Conclusions: Administration of a singlehigh dose of vitamin D3 leads to a significant increase in concentrations of25(OH)D3, 24,25(OH)2D3, 3-epi-25(OH)D3 and 1,25(OH)2D3;induction of the catabolic pathway predominates over the production of 1,25(OH)2D3.Due to the high inter-individual variation in the 25(OH)D3 response to supplementation,any given dose of vitamin D is unlikely to achieve optimal vitamin D status inall treated individual

    1861-11-02 D.M. Howard, David Bugbee, and William Arnold invite Governor Washburn to event for John Goddard

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    https://digitalmaine.com/cw_me_1st_cav/1168/thumbnail.jp
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