Linear dependence tests for determination of number of chemical species

1976 ◽  
Vol 80 (7) ◽  
pp. 690-693 ◽  
Author(s):  
Edwin H. Lane ◽  
Sherril D. Christian ◽  
Frank Garland
Author(s):  
John Ross ◽  
Igor Schreiber ◽  
Marcel O. Vlad

In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.


1994 ◽  
Vol 147 ◽  
pp. 161-185
Author(s):  
Enrique Garcia-Berro ◽  
Margarida Hernanz

AbstractThe inclusion of a detailed treatment of solidification processes in the cooling theory of carbon–oxygen white dwarfs is of crucial importance for the determination of their luminosity function. Carbon–oxygen separation at crystallization yields delays larger than 2 Gyr to cool down to luminosities corresponding to the observed cut–off. This leads to estimates of the age of the galactic disk 1.5 to 2 Gyr older than the ones obtained in previous studies (about 9 Gyr). Furthermore, the presence of minor chemical species, in particular 22Ne, alters significantly the crystallization process, and produces extra delays of 2 to 3 gigayears. However, the detailed computation of the theoretical white dwarf luminosity function, taking into account a reasonable model of galactic chemical evolution, and including the effect of these species, shows that the location of the cut–off, and then the estimated age of the disk, is not modified significantly.


1994 ◽  
Vol 6 (4) ◽  
pp. 113-118
Author(s):  
Ildikó Bódog ◽  
Klára Polyák ◽  
József Hlavay

2018 ◽  
Vol 107 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Akihiko Yokoyama ◽  
Yuta Kitayama ◽  
Yoshiki Fukuda ◽  
Hidetoshi Kikunaga ◽  
Masashi Murakami ◽  
...  

Abstract The aim of this study was to identify relevant Rf chemical species by using reversed-phase extraction chromatography with 2-thenoyltrifluoroacetone (TTA) resin as the stationary phase. Because TTA can be used to extract specific metal ions, the distribution ratios of the system enabled determination of the specific complex formation constant of Rf. We performed several experiments on chemical systems with Zr, Hf, No, and Rf, determined their adsorption coefficients, and deduced the Kd values for Rf.


2011 ◽  
Vol 356-360 ◽  
pp. 1306-1314 ◽  
Author(s):  
Ming Jun Ji ◽  
Yoshihiko Ninomiya ◽  
Zhong Bing Dong ◽  
Qun Ying Wang

Two chinese bituminous coals used in coal-fired power plants are combusted under air conditions in a lab-scale drop tube furnace. The effects of minerals transformation on the formation of PM 2.5 are investigated during the combustion of coal blends. The collected PM were subjected to Computer controlled scanning electron microscopy (CCSEM) and High-resolution transmission electron microscopy(HRTEM) coupled with energy dispersive X-ray spectroscopy (EDX) analysis for determination of chemical species within them. The results show that PM 2.5 emissions are not linearly related to the wt.% of the parent coal or coal blends. Transformations of fine Si-Al mineral grains provided by the minerals in coal XQ into coarse particles (>2.5 μm in diameter) are responsible for the reduction of PM1-2.5 during the combustion of coal blending. The transformed fine Si-Al particles are captured by the coarse Ca-Mg-Al-Si provided by the minerals in coal HT to form larger Ca-Mg-Al-Si particles (>2.5 μm in diameter). Increasing Ca and Mg concentration in coal blends enhances the liquid concentration produced during combustion and hence affects the emissions of PM1 and PM1-2.5.Through adjusting the mineral compositions in coal blends, the reduction of PM1 and PM1-2.5 emissions can be achieved during combustion.


1997 ◽  
Vol 204 (3) ◽  
pp. 215-221 ◽  
Author(s):  
Xiaolin Hou ◽  
Chifang Chai ◽  
Qinfang Qian ◽  
Xiaojun Yan ◽  
Xiao Fan
Keyword(s):  

2006 ◽  
Vol 530-531 ◽  
pp. 59-64
Author(s):  
V.L.R. Salvador ◽  
Nelson Batista de Lima

This paper presents a new method to separate interfering spectra obtained in wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This method permits improved results to be obtained, compared to conventional analytical results and enables the determination of chemical species of the same element without chemical separation. This is done by separation of the spectra due to electronic transitions of the valence electrons. The Rietveld method [11] overcomes the problem of superimposed peaks of the species present in the specimen and simultaneously enables determination of the species and does not require standard specimens and calibration curves. This signifies a marked improvement in comparison to other techniques. Specimen surface preparation to obtain spectra is a critical stage and its effects can be minimized by using Rietveld refinement, which permits the determination of intensity relationships of superimposed peaks with the aid of mathematical models. This establishes the basic conditions to obtain more accurate results in quantitative analysis. In the determination of chemical species, it is possible to separate, for example, Cr (III) and Cr (IV), with almost 100% superimposition.


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