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11.
The application of two chemometric techniques for data structure analysis (Ward's hierarchical clustering and Principal Components Analysis) has permitted the characterization of 5th century A.D. amphora-producing centres in the Mediterranean on the basis of X-ray fluorescence data on 66 amphora fragments. The chemometric study complements and reinforces the conclusions drawn from typological and archaeological analysis. Nineteen samples of unknown origin have been classified (using the SIMCA method) into the eight proposed classes of amphora production. 相似文献
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Ratnamma Pasar Pallavi MS Harischandra Naik R Devaraj M Nandini P Bheemanna M Badariprasad P R Paramasivam M 《Journal of separation science》2022,45(11):1831-1838
This study presents the method development, validation, and simultaneous determination of dimethoate and its metabolite omethoate in curry leaf. Samples were extracted following modified quick, easy, cheap, effective, rugged, and safe extraction protocol and analyzed using liquid chromatography-tandem mass spectrometry. The limit of quantification in the matrix was 0.005 μg g−1 for dimethoate and omethoate. Extraction using acetonitrile recorded the average recoveries in the range of 82.25 to 112.97% for dimethoate and 85.57 to 107.22% for omethoate at 0.005, 0.025 and 0.050 μg g−1 fortification levels and relative standard deviation less than 5%. Similarly, the relative standard deviation values for intraday (Repeatability) and interday (Reproducibility) tests were less than 15%. Dissipation kinetics of dimethoate 30% emulsifiable concentrate at 200 and 400 g a.i h−1 recorded initial deposits of 5.20 and 10.05 μg g−1 and 0.33 and 0.48 μg g−1 for dimethoate and omethoate, respectively, and half-life of 3.07 and 3.34 days. The estimated hazard index value found more than one at a day after dimethoate application. It is not safe for consumer health to use curry leaves in the initial days after application. 相似文献
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A 23 factorial design has been used to analyze the effect of pH, the nature of the catalyst, and the concentration of the substrate
on the rate constant of the photodegradation reaction of phenol. The main effects of the considered variables and their interaction
are discussed. The significance of the effects has been corroborated using an ANOVA test. The values of phenol concentrations,
used to calculate the rate constant, and the concentrations of intermediates were obtained by applying parallel factor (PARAFAC)
analysis to the data obtained from monitoring the process by means of excitation–emission fluorescence (EEM). The proposed
methodology, which combines experimental design and multivariate techniques, is a rapid alternative for study of chemical
kinetics. 相似文献
15.
Martí-Aluja I Ruisánchez I Cádiz V Maspoch S Larrechi MS 《Analytical and bioanalytical chemistry》2011,399(6):1975-1982
The existence of an enone–dienol tautomerism in enone-containing triglyceride, obtained from high oleic sunflower oil, was
detected in an image set captured at 95 °C by fixed-size image window-evolving factor analysis. A 1H NMR spectrum and a UV–Visible spectrum of the enone-containing triglyceride at 25 °C and at 95 °C were measured to corroborate
the presence of the enol form. The presence of this equilibrium explains the different behaviour of the curing reaction between
an enone-containing triglyceride and diaminodiphenylmethane, which was evaluated following the spectral evolution of two pixels
that differ in the presence or absence of the enol form. As the enol form acts as a inert species in the reaction, it leads
to different degree of advance depending on which growing zone is observed. 相似文献
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OK Yoon WG Hwang JC Choe MS Kim 《Rapid communications in mass spectrometry : RCM》1999,13(14):1515-1521
A technique to investigate photodissociation kinetics on a nanosecond time scale has been devised for molecular ions generated by multiphoton ionization (MPI) using mass-analyzed ion kinetic energy spectrometry. The branching ratio or rate constant has been determined for the photodissociation of the n-butylbenzene, bromobenzene, iodobenzene, and aniline molecular ions generated by MPI at 266 nm. The ion internal energies have been estimated by comparing the measured kinetic data with the previous energy dependence data. The analysis has shown that only those molecular ions generated by two-photon ionization contribute to the photodissociation signals. Around half of the available energy has been found to remain as molecular ion internal energy in the two-photon ionization process. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Near-infrared spectroscopy and multivariate calibration for the quantitative determination of certain properties in the petrochemical industry 总被引:3,自引:0,他引:3
Near-infrared (NIR) spectroscopy in conjunction with chemometric techniques allows on-line monitoring in real time, which can be of considerable use in industry. If it is to be correctly used in industrial applications, generally some basic considerations need to be taken into account, although this does not always apply. This study discusses some of the considerations that would help evaluate the possibility of applying multivariate calibration in combination with NIR to properties of industrial interest. Examples of these considerations are whether there is a relation between the NIR spectrum and the property of interest, what the calibration constraints are and how a sample-specific error of prediction can be quantified. Various strategies for maintaining a multivariate model after it has been installed are also presented and discussed. 相似文献
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First, the basic concept of the vector derivative in geometric algebra is introduced. Second, beginning with the Fourier transform
on a scalar function we generalize to a real Fourier transform on Clifford multivector-valued functions
Third, we show a set of important properties of the Clifford Fourier transform on Cl3,0 such as differentiation properties, and the Plancherel theorem. Finally, we apply the Clifford Fourier transform properties
for proving an uncertainty principle for Cl3,0 multivector functions. 相似文献
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Relaxation of toroidal discharges is described by the principle of minimum energy dissipation together with the constraint
of conserved global helicity. The resulting Euler-Lagrange equation is solved in toroidal coordinates for an axisymmetric
torus by expressing the solutions in terms of Chandrasekhar-Kendall (C-K) eigenfunctions analytically continued in the complex
domain. The C-K eigenfunctions are obtained as hypergeometric functions that are solutions of scalar Helmholtz equation in
toroidal coordinates in the large aspect-ratio approximation. Equilibria are constructed by assuming the current to vanish
at the edge of plasma. For the m=0, n=0 (m and n are the poloidal and toroidal mode numbers respectively) relaxed states, the magnetic field, current, q (safety factor) and pressure profiles are calculated for a given value of aspect-ratio of the torus and for different values
of the eigenvalue λ
r
0. The new feature of the present model is that solutions allow for both tokamak as well as RFP-like behaviour with increase
in the values of λ
r
0, which is related directly to volt-sec in the experiment. 相似文献