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201.
The inhibition-release titration method has been used to study interference effects in flame atomic-absorption determination of iron. Interferences from anions, cations and complexing agents with the atomic-absorption of iron when a stoichiometric air-acetylene flame is used, can be obviated by a preliminary treatment of the sample solution with sulphosalicylic acid to convert the iron into the same complex before aspiration, thus giving a constant environment for the iron in the flame processes. 相似文献
202.
203.
S. Amini 《BIT Numerical Mathematics》1983,23(3):322-328
The concept of (A
0,S)-stability, for numerical methods approximating solutions of Volterra integral equations, is formally defined. New stability polynomials for the recent multi-lag type methods are obtained. (A
0, 1)-stability of these and other methods employing reducible quadrature rules are also investigated. 相似文献
204.
205.
206.
Mostafa A. Abdelkader 《Applied Scientific Research》1965,12(1):48-56
Summary Considered here first is a circuit consisting of resistanceR, inductanceL, capacitanceK, in series with a periodically variable capacitanceC(1 + cos t), with maximum value 2C and minimum value zero (i.e. open circuit). The exact solution of the Hill-type differential equation for the charge on the condensers is shown to be expressible in terms of associated Legendre functions of general degree and order. However, considerable analytical simplification is effected by appropriate choice of the value of capacitanceK, for then the solution (likewise exact) is in terms of more elementary functions. It is found that the value of the angular frequency , in relation to the circuit parameters, influences the character of the solution, which varies considerably with . Secondly, a lossless circuit consisting of a variable inductanceM(1+cos t), shunted by a fixed inductanceL and a capacitanceC, is considered. As before, appropriate choice ofL simplifies the solution functions. Actually, the circulating charge in the variable-inductance case has the same mathematical expression as that for the current in the variable-capacitance case. 相似文献
207.
Nicolas Popoff Jeff Espinas Eric Gour Olivier Boyron Erwan Le Roux Jean‐Marie Basset Rgis M. Gauvin Aimery De Mallmann Mostafa Taoufik 《Macromolecular rapid communications》2011,32(23):1921-1924
Silica‐supported titanium(IV) chloride is readily reduced by Mashima and co‐workers' reagent (1‐methyl‐3,6‐bis(trimethylsilyl)‐1,4‐cyclohexadiene) to afford materials active in ethylene polymerisation without need of aluminum alkyl cocatalyst. 相似文献
208.
Huge amounts of data in hyperspectral images have been caused to represent approaches for the band selection of these images.
In this paper, a new approach based on independent component analysis (ICA) is proposed. The idea of projection pursuit is
used to order the bands on the basis of a non-gaussianity distribution. Applying a negentropy function to weight bands is
a novel idea that leads to the selection of bands with minimum mutual information (MI) and besides maximum entropy, with respected
to the bands selected using other methods. 相似文献
209.
Mostafa Shourian Hassan Tavakoli Hedayatollah Ghourchian Hossain-Ali Rafiee-Pour 《Radiation measurements》2010,45(8):906-910
This report describes the detection and dosimetry of gamma ray emitted from Thallium-201 (201Tl) and Technetium-99m (99mTc) based on chemiluminescence technique. H2O2 produced by two gamma emitter radioisotopes of 201Tl and 99mTc were quantitatively measured by chemiluminescence method. Upon producing H2O2 in a luminol alkaline solution, in the presence of diperiodatocuprate, as catalyst a chemical reaction was accrued and consequently the emitted light was measured. The determined H2O2 concentration was correlated with the gamma ray detection and dosimetry. The sensitivity of chemiluminescence technique for 201Tl and 99mTc dosimetry was determined to be 0.20 and 0.08 MBq/l (Mega Becquerel per liter) respectively (R.S.D. = %5, N = 3). The plotted calibration curves showed detection limits of 3.24 and 1.76 MBq/l for 201Tl and 99mTc, respectively. 相似文献
210.
Antignac JP Marchand P Gade C Matayron G Qannari el M Le Bizec B Andre F 《Analytical and bioanalytical chemistry》2006,384(1):271-279
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are widely recognized by the scientific community as persistent organic
pollutants due to their toxicity and adverse effects on wildlife and human health. The actual regulation dedicated to the
monitoring of dioxins in food is based on the measurement of 17 congener concentrations. The final result is reported as a
toxic equivalent value that takes into account the relative toxicity of each congener. This procedure can minimize the qualitative
information available from the abundances of each PCDD/PCDF congener: the characteristic contamination profile of the sample.
Multivariate statistical techniques, such as principal component analysis (PCA) or linear discriminant analysis (LDA), represent
an interesting way to investigate this qualitative information. Nevertheless, they have only been applied to the analysis
of contamination data from food products and biological matrices infrequently. The objective of the present study was to analyze
a large data set from dioxin analyses performed on various food products of animal origin. The results demonstrate the existence
of differences in congener-specific patterns between the analyzed samples. Variability was first demonstrated in terms of
the food type (fish, meat, milk, fatty products). Then a variability was observed that was related to the specific animal
species for meat and milk samples (bovine, ovine, porcine, caprine and poultry). Some practical applications of these results
are discussed. The origin(s) of the observed differences, as well as their significance, now remain to be investigated, both
in terms of environmental factors and transfer through living organisms. A better knowledge of the relation between a contamination
profile and its specific source and/or food product should be of great interest to scientists working in the fields of contaminant
analysis, toxicology and metabolism, as well as to regulatory bodies and risk assessors in charge of final decisions regarding
the eventual hazards associated with theses substances. 相似文献