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31.
32.
本文对钕玻璃的光泵感应热畸变作了理论分析,给出了光泵感应热畸变与钕玻璃热光性质的关系,并对高重复率脉冲器件和单次脉冲器件作了热畸变的定量测量,实验结果在一定程度上与理论分析相符。 相似文献
33.
E. M. Krupp Christophe Pécheyran Simon Meffan-Main Olivier F. X. Donard 《Analytical and bioanalytical chemistry》2001,370(5):573-580
The precision and accuracy of lead isotope-ratio determination on a short transient signal has been assessed by coupling capillary gas chromatography to the Isoprobe (Micromass, UK), a single-focusing inductively coupled plasma mass spectrometer with multicollector detection. A T-piece connecting the GC transfer line to the torch enabled continuous aspiration of thallium solution for mass-bias correction. The volatile lead species PbEt4 was derivatized from NIST isotopic certified lead standard SRM 981 and different amounts of PbEt4 dissolved in iso-octane were injected into the GC. Chromatograms were recorded in multicollection mode by use of Faraday cups; seven isotopes (204Pb, 206Pb, 207Pb, 208Pb, 203Tl, 205Tl, and 202Hg) were monitored simultaneously at a transient resolution of 160 ms. PbEt4 peaks were obtained with a half-width of 1.2 s and a base width of 3.5 s. Lead isotope ratios were calculated from the peak areas integrated for each lead isotope, giving precision in the range of 0.02 to 0.07% for ratios of high-abundant isotopes and injections of 5 and 50 pg absolute amount as lead (five replicates). Mass bias was found to be about 0.5% per mass unit and was corrected by using the continuously measured thallium signals at 203Tl and 205Tl. After mass-bias correction, deviation of the certified lead ratio values was found to be in the range of 0.02 to 0.15% accuracy. 相似文献
34.
Julien Malherbe Hervé Martinez Beatriz Fernández Olivier F. X. Donard 《Analytical and bioanalytical chemistry》2010,396(8):2841-2853
The effect of radiofrequency glow-discharge sputtering on the sample surface in terms of modifications in the surface morphology
were investigated in this work by using atomic force microscopy (AFM) and rugosimetry measurements. The influence of GD operating
parameters (e.g. rf power, discharge pressure and sputtering time) on surface roughening was investigated using two different
types of samples: mirror-polished and homogeneous silicon wafers and chromate conversion coatings (CCCs). Surface morphology
changes produced by GD sputtering into the sample surface were carefully investigated by AFM and rugosimetry, both at the
original sample surface and at the bottom of GD craters using different GD experimental conditions, such as the sputtering
time (from 1 s to 20 min), rf forward power (20–60 W for the Si wafer and 10–60 W for the CCC), and discharge pressure (400–1,000 Pa
for the Si wafer and 500–1000 Pa for the CCC). In the present study, GD-induced morphology modifications were observed after
rf-GD-OES analysis, both for the silicon wafers and the CCC. Additionally, the changes observed in surface roughness after
GD sputtering were found to be sample-dependent, changing the proportion, shape and roughness of the micro-sized patterns
and holes with the sample matrix and the GD conditions. 相似文献
35.
Séby F Gagean M Garraud H Castetbon A Donard OF 《Analytical and bioanalytical chemistry》2003,377(4):685-694
A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP–MS). High resolution (HR) ICP–MS was used to examine the influence of polyatomic interferences on the detection of the 52Cr+ and 53Cr+ isotopes. If there was strong interference with m/z 52 for plastic materials, it was possible to use quadrupole ICP–MS for m/z 53 if digestions were performed with HNO3+H2O2. This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH4+/NH3 buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC–ICP–MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc–nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient. In the case of painted metallic plate, because of a reactive matrix towards Cr(VI), its extraction without degradation was difficult to perform. 相似文献
36.
R. Cornelis C. Camara L. Ebdon L. Pitts B. Welz R. Morabito O. Donard H. Crews E. H. Larsen B. Neidhart F. Ariese E. Rosenberg D. Mathé G. M. Morrison G. Cordier F. Adams P. Van Doren J. Marshall B. Stojanik A. Ekvall P. Quevauviller 《Analytical and bioanalytical chemistry》1999,363(5-6):435-438
The main objective of the EU-network is to bring together scientists with a background in analytical chemistry interested in speciation method development with potential users from industry and representatives from legislative bodies. The network started on 1/10/1997 for a duration of 2 years. A series of meetings are being organised to debate all the important questions for collecting information on environmental, food and occupational health aspects of speciation and to define possible future projects. The findings and conclusions will be summarised as a series of general papers that will be published in the open literature, recapitulating the essential information gathered to date, outlining the state of the art for each topic and recommending legislative actions. A first meeting was held in Überlingen, Germany on 5–6 December 1997. The representatives from industry explained their interest in the network and the participants from the academic and national institutes gave a state-of-the-art presentation of their research. Out of this, a program was compiled for the following meeting in Segovia from 16 to 20 March 1998. The topics dealt with were: organotin compounds in the environmental session; the speciation and bioavailability of trace element species (Cr, Fe, Se), the quality of the data and new legislation in the food session; and identification of inhaled particles and the search for bioindicators for exposure to Ni and Pt in the occupational health/hygiene session. In each session about half of the participants came from industry. The delegates agreed on a list of priorities in speciation analysis. A www-page has been created: hhtp://www. speciation 21.plymouth.ac.uk. Everybody interested in adding information to the page is requested to mail this to lpitts@plymouth.ac.uk 相似文献
37.
Ricard E Pécheyran C Sanabria Ortega G Prinzhofer A Donard OF 《Analytical and bioanalytical chemistry》2011,399(6):2153-2165
IR-femtosecond pulses were used at high repetition rates (up to 10 kHz) to ablate viscous crude oils for the determination
of trace elements by ICPMS. A special internal glass cap was fitted into the ablation cell to minimise oil splashes and remove
big particles that would be otherwise spread into the cell. Laser ablation in static and dynamic conditions (i.e. the laser
beam being moved rapidly at the surface of the sample) was studied together with some fundamental parameters like repetition
rate and fluence. Signal sensitivity and stability were found to be strongly affected by repetition rate and fluence, though
not in linear manner, and in some circumstances by the laser beam velocity. Sample transport efficiency was found to decrease
with increasing repetition rate, probably due to stronger particle agglomeration when increasing the density of primary particles.
ICPMS plasma atomisation/ionisation efficiency was also found to be affected to some extent at the highest repetition rates.
Moderate repetition rate (1 kHz), high fluence (24 J cm−2) and fast scanning velocity (100 mm s−1) were preferred taking into account signal intensity and stability. Sample transport elemental fractionation was also evidenced,
particularly as regards to carbon due to volatilisation of volatile organic species. Matrix effect occurring when comparing
the ablation of transparent (base oil) and opaque (crude oil) samples could not be completely suppressed by the use of IR
femtosecond pulses, requiring a matrix matching or a standard addition calibration approach. This approach provided good accuracy
and very low detection limits in the crude oil, in the range of ng g−1. 相似文献
38.
The toxicity of butyltin, phenyltin and inorganic tin compounds to three pure strains of sulfate‐reducing bacteria (SRB), isolated from a tributyltin (TBT)‐polluted sediment, was determined. The isolated strains were identified as belonging to the genus Desulfovibrio. A new toxicological index (GR25) was developed to assay the toxicity of organotin compounds. Deleterious effects on suspended anaerobic cell cultures were observed for concentrations ranging between 500 and 600 µM for tin tetrachloride, 55 and 260 µM for triorganotins, 30 and 90 µM for diorganotins, and 1 and 6 µM for mono‐organotins. Whereas the number of substituents influenced the toxicity of organotins, the type of substituent (butyl or phenyl) proved to have little or no impact. Trisubstituted compounds (tributyl‐ and triphenyl‐tin) were less toxic to these strains of SRB than the monosubstituted forms (monobutyl‐ and monophenyl‐tin). This is the opposite trend to that currently reported for aerobic organisms. Under the given anoxic conditions, the toxicity of organotin compounds obtained yielded a significant negative correlation with the total surface area (TSA) of the tested molecules. Comparison of the TBT toxicity data observed for different microbial groups suggests that the tolerance of bacteria to organotin compounds might be related to organotin–cell wall interactions as well as to aerobic or anaerobic metabolise pathways. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
39.
Donard OF Bruneau F Moldovan M Garraud H Epov VN Boust D 《Analytica chimica acta》2007,587(2):170-179
Among the transuranic elements present in the environment, plutonium isotopes are mainly attached to particles, and therefore they present a great interest for the study and modelling of particle transport in the marine environment. Except in the close vicinity of industrial sources, plutonium concentration in marine sediments is very low (from 10−4 ng kg−1 for 241Pu to 10 ng kg−1 for 239Pu), and therefore the measurement of 238Pu, 239Pu, 240Pu, 241Pu and 242Pu in sediments at such concentration level requires the use of very sensitive techniques. Moreover, sediment matrix contains huge amounts of mineral species, uranium and organic substances that must be removed before the determination of plutonium isotopes. Hence, an efficient sample preparation step is necessary prior to analysis. Within this work, a chemical procedure for the extraction, purification and pre-concentration of plutonium from marine sediments prior to sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) analysis has been optimized. The analytical method developed yields a pre-concentrated solution of plutonium from which 238U and 241Am have been removed, and which is suitable for the direct and simultaneous measurement of 239Pu, 240Pu, 241Pu and 242Pu by SF-ICP-MS. 相似文献
40.
91.IntroductionTheso-calledWestwaterprocessisthecoordinateprocessunderthepolymermeasureu(g)in3-dimensionsconstructedbyWestwater(see[7,8]),andthepolymermeasurev(g)onCo([O,1]-R')isformallydefinedbywhereC,isthenormalization,gE[o,oo)isacouplingconstant,pistheWienermeasureonCo([o,11-R').Inarecentpaper(see[9]),weprovedthattheHausdorffdimensionofthesamplepathoftheWestwaterprocess{X,,t6[O,1]}isalsotwowithprobability1tou(g).Actually,weprovedin[9]thatgh(ImX)5C,y(g)-a.e.(1.1)m(ImX)5C,y(g)-a.e.(1.… 相似文献