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211.
The non-parametric estimation of the average growth curve has been extensively studied in both stationary and some non-stationary particular situations. In this Note, we consider the statistical problem of estimating the average growth curve for a fixed design model with a non-stationary error process. The non-stationarity considered here is of a general form, and this note may be considered as an extension of previous results. The optimal bandwidth is shown to depend on the singularity of the autocovariance function of the error process along the diagonal. To cite this article: K. Benhenni, M. Rachdi, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
212.
Nadia Mustapha Inès Bouhlel Fadwa Chaabane Imèn Mokdad Bzéouich Kamel Ghedira Thierry Hennebelle Leila Chekir-Ghedira 《Applied biochemistry and biotechnology》2014,172(4):2266-2275
The present study was carried out to characterize the cellular antioxidant effect of the aqueous extract of Crataegus azarolus and its antigenotoxic potential using human myelogenous cells, K562. The antioxidant capacity of this extract was evaluated by determining its cellular antioxidant activity (CAA) in K562 cells. Also, preceding antigenotoxicity assessment, its eventual genotoxicity property was investigated by evaluating its capacity to induce the DNA degradation of treated cell nuclei. As no genotoxicity was detected at different exposure times, its ability to protect cell DNA against H2O2 oxidative effect was investigated, using the “comet assay.” It appears that 800 μg/mL of extract inhibited the genotoxicity induced by H2O2 with a rate of 41.30 %, after 4 h of incubation. In addition, this extract revealed a significant cellular antioxidant capacity against the reactive oxygen species in K562 cells. 相似文献
213.
A GC–MS/MS method with EI ionization was developed and validated to detect and quantify N-nitrosodimethylamine (NDMA) and seven other nitrosamines in 105 samples of metformin tablets from 13 different manufactures. Good linearity for each compound was demonstrated over the calibration range of 0.5–9.5 ng/mL. The assay for all substances was accurate and precise. NDMA was not detected in the acquired active pharmaceutical ingredient (API); however, NDMA was detected in 64 (85.3%) and 22 (91.7%) of the finished product and prolonged finished product samples, respectively. European Medicines Agency recommends the maximum allowed limit of 0.032 ppm in the metformin products. Hence, 28 finished products and 7 pronged dosage products were found to exceed the acceptable limit of daily intake of NDMA contamination. The implications of our findings for the testing of pharmaceutical products are discussed. 相似文献
214.
Siham Amra Thierry Bataille Saliha Bourouina Bacha Mustapha Bourouina Didier Hauchard 《Electroanalysis》2020,32(6):1346-1353
A new electrochemical sensor based on nanostructured carbon paste electrodes (CPEs) is developed for the sensitive detection of Isoproturon in water. The CPEs were nanostructured by incorporation of carbon nanotubes (NTCs) and synthetized copper oxide nanoparticles (CuO). They were characterized using the X‐ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and voltammetric methods. Electrochemical experiments showed that the adsorption of Isoproturon on to (GC‐NTC‐CuO)‐CPE, associated with nanomaterials (NTCs and CuO), provided remarkable analytical performances of the sensor such as a large quantification range from 1 to 200 μg L?1 with a detection limit of 0.1 μg L?1 of Isoproturon and no interferences of some another pesticides tested (specificity of ISO adsorption in acidified water). The tests carried out on real samples of water are conclusive. The analytical performances of the sensor showed that it is suitable for the specific determination of pesticide traces in water. 相似文献
215.
Maite de Blas Marino Navazo Lucio Alonso Nieves Durana Jon Iza 《International journal of environmental analytical chemistry》2013,93(2):228-244
The measurement of halogenated hydrocarbons in the atmosphere is a matter of great interest owing to their adverse effects on the human health and the environment. This work is focused on the measurement of three toxic chlorinated hydrocarbons: trichloroethylene (TCE), tetrachloroethylene (PCE), and carbon tetrachloride (CTC). Moreover, CTC is a greenhouse gas and an ozone depleting gas, restricted under the Montreal Protocol. Owing to their low reactivity, the target chlorinated hydrocarbons are considered to be persistent and, thus, many measurements only address their mean mixing ratios (a concentration measure expressed as mol/mol). Consequently, most of the reported data have low temporal resolution as daily, seasonal or yearly mean mixing ratios, obtained with few measurements. In the study reported in this paper hourly measurements were performed for a long period of time: almost two years for TCE and PCE, and one year for CTC. The main objective was to study the temporal variability of the chlorinated hydrocarbons with high temporal resolution in order to identify their main sources and to enhance the understanding of their atmospheric processes. During the measurement period, March 2007–February 2008 with N?=?3290 valid data, CTC showed a mean mixing ratio of 0.16?ppbv (SD?=?0.13) with lower temporal variability than the majority of non-methane hydrocarbons (NMHCs), being very well mixed in the urban atmosphere owing to its long lifetime. TCE and PCE mean mixing ratios for the May 2006–February 2008 period, were 0.13?ppbv (SD?=?0.42, N?=?4601) and 0.25?ppbv (SD?=?0.54, N?=?4709) respectively, with a larger temporal variability. The study of the sources of TCE and PCE reveals that both compounds have industrial and/or commercial origin, but with different main sources. 相似文献
216.
We propose the concept of three-dimensional (3D) microwell arrays for cell culture applications and highlight the importance of oxygen diffusion through pores in all three dimensions to enhance cell viability. 相似文献
217.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献
218.
Colum Breen Robert Pal Mark R. J. Elsegood Simon J. Teat Felipe Iza Kristian Wende Benjamin R. Buckley Stephen J. Butler 《Chemical science》2020,11(12):3164
Peroxynitrite (ONOO−) is a powerful and short-lived oxidant formed in vivo, which can react with most biomolecules directly. To fully understand the roles of ONOO− in cell biology, improved methods for the selective detection and real-time analysis of ONOO− are needed. We present a water-soluble, luminescent europium(iii) probe for the rapid and sensitive detection of peroxynitrite in human serum, living cells and biological matrices. We have utilised the long luminescence lifetime of the probe to measure ONOO− in a time-resolved manner, effectively avoiding the influence of autofluorescence in biological samples. To demonstrate the utility of the Eu(iii) probe, we monitored the production of ONOO− in different cell lines, following treatment with a cold atmospheric plasma device commonly used in the clinic for skin wound treatment.Reactivity-based europium(iii) probe displays excellent selectivity for peroxynitrite (ONOO−), enabling its time-resolved luminescence detection in living cells. 相似文献
219.
Mustapha Mekhfi 《International Journal of Theoretical Physics》2000,39(4):1163-1169
We investigate the internal space of Bessel functions which is associated to thegroup Z of positive and negative integers defining their orders. As a result wepropose and prove a new unifying formula (to be added to the huge literatureon Bessel functions) generating Bessel functions of real orders out of integerorder ones. The unifying formula is expected to be of great use in appliedmathematics. Some applications of the formula are given for illustration 相似文献
220.
We propose and analyze a fully discrete H
1-Galerkin method with quadrature for nonlinear parabolic advection–diffusion–reaction equations that requires only linear
algebraic solvers. Our scheme applied to the special case heat equation is a fully discrete quadrature version of the least-squares
method. We prove second order convergence in time and optimal H
1 convergence in space for the computer implementable method. The results of numerical computations demonstrate optimal order
convergence of scheme in H
k
for k = 0, 1, 2.
Support of the Australian Research Council is gratefully acknowledged. 相似文献