1,248 research outputs found

    A Comparison of Coated Paper Surfaces by Photomicrography

    Get PDF
    Five different types of coated papers were photomicrographed, namely cast coated, roll coated, trailing blade coated, air brush coated, and brush coated grades. All cast coated papers were found to be extremely smooth and essentially free of pattern. Roll coated papers displayed a microscopic pattern which resembled the magnified surface of an orange peel. Trailing blade coated papers displayed sharp-edged pits and, in some cases, scuffed surfaces. Air brush coated papers had a microscopic pattern which resembled the non-magnified surface of a pie crust. Brush coated papers closely resembled air brush coated papers microscopically, however, they also carried a macroscopic pattern of brush marks which distinguished them from the air brush coated grades. It was concluded that various types of coating processes leave typical patterns which may be used in conjunction with other characteristics of the paper to identify the particular coating process used

    The control of calcium metabolism by parathyroid hormone, calcitonin and vitamin D

    Get PDF
    Advances in analysis of chemistry and physiology of parathyroid hormone, calcitonin, and Vitamin D are described along with development of techniques in radioassay methods. Emphasis is placed on assessment of normal and abnormal patterns of secretion of these hormones in specific relation to the physiological adaptations of weightlessness and space flight. Related diseases that involve perturbations in normal skeletal and calcium homeostasis are also considered

    TLC determination of functionality in prepolymers

    Get PDF
    Application of thin-layer chromatographics provides rapid qualitative determination of functional distribution in experimental prepolymer. Functionality distribution is of fundamental importance for it determines; (1) manner in which given carboxyl-terminated prepolymer will cure and (2) physical properties of resulting product

    Glass transition temperatures of liquid prepolymers obtained by thermal penetrometry

    Get PDF
    Thermal penetrometry is experimental technique for detecting temperature at which frozen prepolymer becomes soft enough to be pierced by weighted penetrometer needle; temperature at which this occurs is called penetration temperature. Apparatus used to obtain penetration temperatures can be set up largely from standard parts

    Community Empowerment through an Academic Product: Implications for the Social-justice

    Get PDF
    Often, African American community organizations are distanced from government institutional practices. In response, they may approach local academics to help bridge the divide. This think piece explores lessons that one academic scholar learned during the process of writing and distributing an applied report that ultimately helped a community organization to gain access to the governmental decision-making process. In exploring the project, we first focus on the process and value of shifting from a charity orientation to a social justice orientation. Second, we use the report itself to provide examples of essential, concrete aspects of social justice-oriented products. In the end, we argue that academic scholars can contribute to community empowerment if (1) an asset rather than deficit orientation is employed and (2) scholars are viewed as community assets rather than institutional resources

    The use of kinematic hardening models for predicting tunnelling-induced ground movements in London Clay

    No full text
    The use of a kinematic hardening soil model for predicting short- and long-term ground movements due to tunnelling in London Clay is investigated. The model is calibrated against oedometer and triaxial tests on intact samples from different units of the London Clay. The calibrated model is then used in finite-element analysis to simulate the field response at St James's Park during excavation of the Jubilee Line Extension tunnels. The finite-element predictions compare well with the available field monitoring data. The importance of using consistent initial conditions for this complex boundary value problem in conjunction with the model parameters selected is highlighted. The stiffness response of different regions of the finite-element mesh indicates that the rate at which the stiffness degrades and the stiffness response further away from the tunnel boundary affect the short-term predictions significantly. The long-term predictions confirm that the compression characteristics of the soil control the magnitude of the consolidation settlements and its permeability the shape of the long-term settlement profiles

    Numerical investigation of the effects of tunnelling on existing tunnels

    Get PDF
    Construction of the Crossrail tunnels just beneath the existing Central line tunnels at the northern side of Hyde Park provided the impetus for this paper. A basic three-dimensional (3D) finite-element (FE) model was developed to study a general case of a new tunnel (NT) crossing perpendicularly below an existing tunnel (ET). A series of 3D FE analyses was carried out and the results presented in this paper reveal some of the interaction effects. Changes in hoop forces, bending moments and lining deformations of the ET due to excavation of the NT are discussed. Conclusions are drawn about how the relative position of the excavation face of the NT in relation to the ET's axis affects the latter's behaviour. Cross-sectional and longitudinal deformations of the ET are discussed, leading to recommendations for field monitoring of similar interaction cases. Two parametric studies were also carried out to quantify the effects of the magnitude of the earth pressure balance machine face pressure and the longitudinal stiffness of the ET on the predicted behaviour of the ET due to construction of the NT

    Saturated hydrocarbon polymeric binder for advanced solid propellant and hybrid solid grains Quarterly report no. 2, 1 Feb. - 30 Apr. 1966

    Get PDF
    Synthesis and analysis of ethylene-neohexene copolymers with other non ketene-imine group free radicals for solid and hybrid grain propellant saturated hydrocarbon binder progra
    • …
    corecore