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71.
The area method was proposed in 1992 to calculate binary and ternary 2-phase equilibria. In its integral form, the method provides both the necessary and sufficient conditions required for the determination of the global minimum reduced Gibbs energy of mixing (Φ). The method has since been applied to the calculation of both pure component and ternary multiphase equilibria in a differential form. However, the extension of the original (2 point) integral area method to the direct calculation of both binary and ternary multiphase equilibria has not been completed. Direct 3 point and modified 2 point search methods have therefore been developed here and used to estimate the phase compositions of a representative binary vapour-liquid-liquid system. The 2 point area method principle has been extended and applied to the calculation of ternary multiphase equilibria using a net volume approach. However, this volume method was found to fail due to an underlying inconsistency in the bounding of the integrated Φ surface by the trial 3-phase region. A new method is proposed that overcomes this problem by minimising the area of intersection between a tangent plane and the Φ surface. This new method has successfully calculated the 3-phase compositions of two simple test systems from a variety of initial mixture starting points. 相似文献
72.
Haines TJ Bionta RM Blewitt G Bratton CB Casper D Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Jones TW Kielczewska D Kropp WR Learned JG Lehmann E LoSecco JM Matthews J Park HS Price LR Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1986,57(16):1986-1989
73.
Observation of a neutrino burst in coincidence with supernova 1987A in the Large Magellanic Cloud 总被引:1,自引:0,他引:1
Bionta RM Blewitt G Bratton CB Casper D Ciocio A Claus R Cortez B Crouch M Dye ST Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG LoSecco JM Matthews J Miller R Mudan MS Park HS Price LR Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak LR Svoboda R Thornton G van der Velde JC Wuest C 《Physical review letters》1987,58(14):1494-1496
74.
75.
The present study sets out to extend the utility of reversed-phase liquid chromatography (RP-HPLC) by demonstrating its ability to monitor dimerization and unfolding of de novo designed synthetic amphipathic alpha-helical peptides on stationary phases of varying hydrophobicity. Thus, we have compared the effect of temperature (5-80 degrees C) on the RP-HPLC (C8 or cyano columns) elution behaviour of mixtures of peptides encompassing amphipathic alpha-helical structure, amphipathic alpha-helical structure with L- or D-substitutions or non-amphipathic alpha-helical structure. By comparing the retention behaviour of the helical peptides to a peptide of negligible secondary structure (a random coil), we rationalize that "temperature profiling" by RP-HPLC can monitor association of peptide molecules, either through oligomerization or aggregation, or monitor unfolding of alpha-helical peptides with increasing temperature. We believe that the conformation-dependent response of peptides to RP-HPLC under changing temperature has implications both for general analysis and purification of peptides but also for the de novo design of peptides and proteins. 相似文献
76.
R.G. Smith J.C. Van Loon J.R. Knechtel J.L. Fraser A.E. Pitts A.E. Hodges 《Analytica chimica acta》1977
An inexpensive 50-ml disposable (hypodermic) syringe is used as the arsine generation vessel. The arsine is passed into a 10-cm long. 10-mm i.d. electrically heated silica tube atomizer with nitrogen carrier gas. Excess of hydrogen is burned off in a hydrogen diffusion flame at the ends of the tube. Samples containing appreciable silica are fused with KOH—MgOXXX while organic samples are digested with H2SO4—H2O2. Parameters affecting the determination of arsenic as arsine have been investigated. Collaborative results on a variety of standard reference materials agree well with literature values. The advantages of the proposed method are that it is sensitive, selective, fast, simple, inexpensive, precise and accurate. 相似文献
77.
Dennis W. Sunal Jeanelle Hodges Cynthia S. Sunal Kevin W. Whitaker L. Michael Freeman Leo Edwards Ronald A. Johnston Michael Odell 《School science and mathematics》2001,101(5):246-257
The focus of this research was to better understand the change processes necessary for university science teaching reform to be successful. The professional development processes involved faculty cognitive perceptions of learning, teaching skills, and pedagogical knowledge, as well as faculty culture in teaching science courses. A series of faculty development programs were conducted at nine U.S. locations to explore, develop strategies, and implement changes in science classrooms. A review of research and these professional development experiences provided a base to carry out research activities related to understanding change in science faculty. Faculty participants in the program from 30 institutions were selected to be involved in the study. Ethnographic and case study approaches were used to collect and analyze data. Many faculty members encountered in this study had conceptions of the change process that inhibited successful action. These research efforts provide a predictive model for assisting faculty change and help determine which faculty professional development efforts may be successful in overcoming barriers to change in undergraduate science classrooms. 相似文献
78.
An alternating direction scheme on a nonuniform mesh for reaction-diffusion parabolic problems 总被引:1,自引:0,他引:1
Clavero C; Jorge JC; Lisbona F; Shishkin={paragraph} GI 《IMA Journal of Numerical Analysis》2000,20(2):263-280
In this paper we develop a numerical method for two-dimensionaltime-dependent reaction-diffusion problems. This method, whichcan immediately be generalized to higher dimensions, is shownto be uniformly convergent with respect to the diffusion problems.This method, which can immediately be generalized to higherdimensions, is shown to be uniformly convergent with respectto the diffusion parameter. 相似文献
79.
Helen Y. Luo Vladimir K. Michaelis Sydney Hodges Robert G. Griffin Yuriy Román-Leshkov 《Chemical science》2015,6(11):6320-6324
A new material MIT-1 comprised of delaminated MWW zeolite nanosheets is made in a one-pot synthesis using a rationally designed organic structure-directing agent (OSDA). The OSDA consists of a hydrophilic head segment that resembles the OSDA used to synthesize the zeolite precursor MCM-22(P), a hydrophobic tail segment that resembles the swelling agent used to swell MCM-22(P), and a di-quaternary ammonium linker that connects both segments. MIT-1 features high crystallinity and surface areas exceeding 500 m2 g–1, and can be synthesized over a wide synthesis window that includes Si/Al ratios ranging from 13 to 67. Characterization data reveal high mesoporosity and acid strength with no detectable amorphous silica phases. Compared to MCM-22 and MCM-56, MIT-1 shows a three-fold increase in catalytic activity for the Friedel–Crafts alkylation of benzene with benzyl alcohol. 相似文献
80.
Jonathan Tennyson Peter F. Bernath Alain Campargue Ludovic Daumont Joseph T. Hodges Oleg L. Polyansky Laurence S. Rothman Ann Carine Vandaele Sophie Fally Tibor Furtenbacher Shui-Ming Hu Boris A. Voronin 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2160-1106
This is the second of a series of articles reporting critically evaluated rotational-vibrational line positions, transition intensities, pressure dependences, and energy levels, with associated critically reviewed assignments and uncertainties, for all the main isotopologues of water. This article presents energy levels and line positions of the following singly deuterated isotopologues of water: HD16O, HD17O, and HD18O. The MARVEL (measured active rotational-vibrational energy levels) procedure is used to determine the levels, the lines, and their self-consistent uncertainties for the spectral regions 0-22 708, 0-1674, and 0-12 105 cm−1 for HD16O, HD17O, and HD18O, respectively. For HD16O, 54 740 transitions were analyzed from 76 sources, the lines come from spectra recorded both at room temperature and from hot samples. These lines correspond to 36 690 distinct assignments and 8818 energy levels. For HD17O, only 485 transitions could be analyzed from three sources; the lines correspond to 162 MARVEL energy levels. For HD18O, 8729 transitions were analyzed from 11 sources and these lines correspond to 1864 energy levels. The energy levels are checked against ones determined from accurate variational nuclear motion computations employing exact kinetic energy operators. This comparison shows that the measured transitions account for about 86% of the anticipated absorbance of HD16O at 296 K and that the transitions predicted by the MARVEL energy levels account for essentially all the remaining absorbance. The extensive list of MARVEL lines and levels obtained are given in the Supplementary Material of this article, as well as in a distributed information system applied to water, W@DIS, where they can easily be retrieved. In addition, the transition and energy level information for H217O and H218O, given in the first paper of this series [Tennyson, et al. J Quant Spectr Rad Transfer 2009;110:573-96], has been updated. 相似文献