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growth of CdS crystals by the physical vapor transport method

Journal of Semiconductors 2009年第10期30卷 17-20页

作者：程红娟徐永宽杨巍于祥潞严如岳赖占平 China Electronics Technology Group Corporation No.46 Research Institute

Based on the physical vapor transport （PVT） method, the growth of large-size CdS crystals inside a vertical semi-closed tube is studied. Firstly, in order to ensure 1D diffusion-advection transport, multi-thin tubes are used in the growth tube. The XRD spectra of the CdS crystal grown in this configuration indicates that the crystal quality has clearly been improved, where the FWHM is 58.5 arcsec. Secondly, theoretical and experimental growth rates under different total pressures are compared; the results show that the experiential growth rate equation is valid for our semi-tube growth, and it could be used to estimate the growth rate and maximum growth time under different total pressures.

关键词： CdS growth rate growth surface the saturated vapor pressure

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A Two-Step growth Curve: Approach to the von Bertalanffy and Gompertz Equations

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Advances in Pure Mathematics 2016年第5期6卷 321-330页

作者： Laura Rogers-Bennett Donald W. Rogers California Department of Fish and Wildlife and Karen C. Drayer Wildlife Health Center UC Davis CA USA Bodega Marine Laboratory Bodega Bay CA USA Chemistry Department Long Island University Brooklyn NY USA Friday Harbor Laboratories Whiteley Center University of Washington Friday Harbor WA USA

Many curves have been proposed and debated to model individual growth of marine invertebrates. Broadly, they fall into two classes, first order (e.g. von Bertalanffy) and sigmoidal (e.g. Gompertz). We provide an innovative approach which demonstrates that the growth curves are not mutually exclusive but that either may arise from a simple three-stage growth model with two steps (k1 and k2) depending on the ratio of the growth parameters . The new approach predicts sigmoidal growth when is close to 1, but if either growth from stage A to stage B or B to C is fast relative to the other, the slower of the two steps becomes the growth limiting step and the model reduces to first order growth. The resulting curves indicate that there is a substantial difference in the estimated size at time t during the period of active growth. This novel two-step rate model generates a growth surface that allows for changes in the rate parameters over time as reflected in the new parameter n(t) = k1(t) - k2(t). The added degree of freedom brings about individual growth trajectories across the growth surface that is not easily mapped using conventional growth modeling techniques. This two (or more) stage growth model yields a growth surface that allows for a wide range of growth trajectories, accommodating staged growth, growth lags, as well as indeterminate growth and can help resolve debates as to which growth curves should be used to model animal growth. This flexibility can improve estimates of growth parameters used in population models influencing model outcomes and ultimately management decisions.=

关键词： growth Model growth surface Rate Equation Staged growth Population Models

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