8,751 research outputs found
Structure and variability of earth's atmosphere Final report
Structure and density variations of earth atmosphere associated with solar flu
Analysis of several relations among atmospheric statistics
Statistical equation relating mean values of pressure, temperature, and density with correction term proportional to covariance between density and temperatur
Purification of Artemisinin from the Product Solution of a Semisynthetic Reaction within a Single Crystallization Step
Purification of Curcumin from Ternary Extract-Similar Mixtures of Curcuminoids in a Single Crystallization Step
Crystallization-based separation of curcumin from ternary mixtures of curcuminoids having compositions comparable to commercial extracts was studied experimentally. Based on solubility and supersolubility data of both, pure curcumin and curcumin in presence of the two major impurities demethoxycurcumin (DMC) and bis(demethoxy)curcumin (BDMC), seeded cooling crystallization procedures were derived using acetone, acetonitrile and 50/50 (wt/wt) mixtures of acetone/2-propanol and acetone/acetonitrile as solvents. Starting from initial curcumin contents of 67–75% in the curcuminoid mixtures single step crystallization processes provided crystalline curcumin free of BDMC at residual DMC contents of 0.6–9.9%. Curcumin at highest purity of 99.4% was obtained from a 50/50 (wt/wt) acetone/2-propanol solution in a single crystallization step. It is demonstrated that the total product yield can be significantly enhanced via addition of water, 2-propanol and acetonitrile as anti-solvents at the end of a cooling crystallization process
Range and structure of ambient density from 30 to 120 km altitude
Range and structure of atmospheric density from 30 to 120 km - analysis of statistical models and deviations from U.S. standard and Patrick reference atmosphere
Evaluating Voluntary Climate Programs in the United States
Despite serving as the principal basis of U.S. climate policy over the past two decades, corporate voluntary environmental programs have been subject to quite limited evaluation. The self-selection of participants—an essential element of such initiatives—poses particular challenges to researchers because the decision to participate may not be random and, in fact, may be correlated with the outcomes. The present study is designed to overcome these problems by gauging the environmental effectiveness of two early voluntary climate change programs with established track records, the U.S. Environmental Protection Agency’s Climate Wise program and the U.S. Department of Energy’s Voluntary Reporting of Greenhouse Gases Program, or 1605(b). Both programs provide quite flexible criteria for firms to participate. Particular attention is paid to the participation decision and how various assumptions affect estimates of program outcomes using propensity score matching methods applied to plant-level Census data. Overall, we find quite modest effects: the reductions in fuel and electricity expenditures from Climate Wise and 1605(b) are no more than 10 percent and probably less than 5 percent. Virtually no evidence suggests a statistically significant effect of either Climate Wise or 1605(b) on fuel costs. Some evidence indicates that participation in Climate Wise led to a slight (3–5 percent) increase in electricity costs that vanished after two years. Stronger evidence suggests that participation in 1605(b) led to a slight (4–8 percent) decrease in electricity costs that persisted for at least three years.voluntary, regulation, energy, climate change
Developing processing techniques for Skylab data
The author has identified the following significant results. The effects of misregistration and the scan-line-straightening algorithm on multispectral data were found to be: (1) there is greatly increased misregistration in scan-line-straightening data over conic data; (2) scanner caused misregistration between any pairs of channels may not be corrected for in scan-line-straightened data; and (3) this data will have few pure field center pixels than will conic data. A program SIMSIG was developed implementing the signature simulation model. Data processing stages of the experiment were carried out, and an analysis was made of the effects of spatial misregistration on field center classification accuracy. Fifteen signatures originally used for classifying the data were analyzed, showing the following breakdown: corn (4 signatures), trees (2), brush (1), grasses, weeds, etc. (5), bare soil (1), soybeans (1), and alfalfa (1)
Preparative gradient chromatography
During a chromatographic separation, it is convenient to keep the essential operating parameters like temperature, pressure, mobile phase flow-rate, and mobile phase composition constant. Though, it is well known that in contrast to this isocratic operation the intelligent modulation of certain operating parameters can improve the separation performance significantly. Such gradient approaches are widely applied in analytical (linear) chromatography to reduce the time of analysis and to enhance the selectivity. In contrast, the extent of application of these gradients is still rather limited in the field of preparative (nonlinear) chromatography. The first part of this paper is devoted to the discussion of the principal differences between linear and nonlinear and isocratic and gradient chromatography. The second part focuses on introducing a countercurrent process that allows separation in a continuous manner, efficiently exploiting a two-step solvent composition gradient. Copyright © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim [accessed February 8th 2013
Developing processing techniques for Skylab data
There are no author-identified significant results in this report
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