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排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Development of quantitative vitellogenin-ELISAs for fish test species used in endocrine disruptor screening 总被引:5,自引:0,他引:5
Nilsen BM Berg K Eidem JK Kristiansen SI Brion F Porcher JM Goksøyr A 《Analytical and bioanalytical chemistry》2004,378(3):621-633
The yolk protein precursor vitellogenin (Vtg) in plasma has proved to be a simple and sensitive biomarker for assessing exposure of fish to environmental estrogens. Within international bodies such as the Organization for Economic Cooperation and Development (OECD) work is ongoing to develop screening and testing programmes for endocrine disrupting effects of new chemicals, and in the focus of this development are the fish test species common carp (Cyprinus carpio), fathead minnow (Pimephales promelas), zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes). In this study we have developed quantitative enzyme linked immunosorbent assays (ELISAs) for Vtg in common carp/fathead minnow, zebrafish and Japanese medaka. The assays were developed using a combination of monoclonal and polyclonal fish Vtg antibodies in a sandwich format, using stabilized Vtg from the test species as a standard. The carp Vtg ELISA has a working range of 1–63 ng/mL, a minimal detection limit of 0.6 ng/mL, and may also be used for quantification of Vtg in fathead minnow. In fathead minnow whole-body homogenate samples, the practical detection limit is 400 ng/mL due to the matrix effect. The zebrafish Vtg ELISA has a working range of 0.5–63 ng/mL, a minimal detection limit of 0.4 ng/mL, and a practical detection limit of 200 ng/mL in whole-body homogenate samples. The medaka Vtg ELISA has a working range of 0.25–16 ng/mL, a minimal detection limit of 0.1 ng/mL, and a practical detection limit of 125 ng/mL in whole-body homogenate samples. The intra- and inter-assay variations were below 20% for all assays. The assays were evaluated with sets of representative samples spanning the wide dynamic range of Vtg-levels found in fish exposed to environmental estrogens, and all three assays are currently undergoing international inter-laboratory validation. 相似文献
2.
Nanowires of an iodine containing Pb-Sb-sulfosalt have been synthesized by chemical vapor transport. Their structure was studied using high-resolution transmission electron microscopy and X-ray powder diffraction. The lattice parameters show values equal to a=4.9801(4) nm, b=0.41132(8) nm (with two-fold superstructure), c=2.1989(1) nm and β=99.918(6)°. These parameters and the results of a multislice simulation are in good agreement with the mineral pillaite, Cu0.10Pb9.16Sb9.84S22.94Cl1.06O0.5 (space group C2/m, a=4.949(1) nm, b=0.41259(8) nm, c=2.1828(4) nm, and β=99.62(3)°). Microprobe and EDX analyses yielded a chemical composition of Cu0.507(5)Pb8.73(9)Sb8.15(8)I1.6S20.0(2) which is close to natural pillaite but contains no oxygen and iodine instead of chlorine. The structure of the investigated material is based on chains of M-S polyhedra (M=Pb or Sb) typical for the architecture of sulfosalts implying iodine atoms in trigonal prismatic coordination with Pb atoms from the M-S polyhedra of neighboring chains. The [010] superstructure of the specimen was found to be unstable under electron beam irradiation with a rapid decrease of the b lattice parameter from 0.8 to 0.4 nm within 5 min. 相似文献
3.
Xiaohua C. Huang Susan G. Stuart Paul F. Bente III Thomas M. Brennan 《Journal of chromatography. A》1992,600(2):289-295
Capillary gel electrophoresis has proven to be a powerful tool in biomedical research. We report our investigation of some of the critical parameters affecting separations of single-stranded DNA fragments as monitored by ultraviolet (UV) absorbance detection. Although not as sensitive as laser-induced fluorescence (LIF), UV absorbance detection allows one to calculate quite accurately, and inexpensively, the molarity of each separated DNA fragment and, moreover, the signal “fading” effect normally observed with LIF detection can be, in many cases, substituted for fluorescence to detect the many different single-stranded DNAs, as well as for detection of sequencing reactions. 相似文献
4.
Tam T. T. N. Nguyen Jesper Østergaard Bente Gammelgaard 《Analytical and bioanalytical chemistry》2015,407(28):8497-8503
5.
Mathiessen B Jensen AT Zhuravlev F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7796-7805
A series of phosphazenium hydrofluorides, P(1)(tBu)·[(18/19)F]HF, P(1)(tOct)·[(18/19)F]HF, P(2)(Et)·[(18/19)F]HF, and P(4)(tBu)·[(18/19)F]HF, was synthesized. The radioactive phosphazenium [(18)F]hydrofluorides were obtained by the one-step formation and trapping of gaseous [(18)F]HF with the respective phosphazene bases. The [(19)F] isotopomers were prepared from the corresponding phosphazene bases and Et(3)N·3HF. Under the design of experiment (DoE)-optimized conditions, P(2)(Et)·HF and P(4)(tBu)·HF fluorinated alkyl chlorides, bromides, and pseudohalides in 76-98% yield, but gave lower yields with iodides and electron-deficient arenes. DoE models showed that fluorination can be performed in glass vessels, and that the reactivity of P(2)(Et)·HF and P(4)(tBu)·HF is dominated by solvent polarity but is insensitive to water to at least 2 equiv. In contrast, P(1)(tBu)·HF and P(1)(tOct)·HF were unstable towards autofluorolysis. DFT calculations were performed to rationalize this finding in terms of diminished steric bulk, higher Parr's electrophilicity, and chemical hardness of P(1)(R)H(+). The corresponding radiofluorination reaction gave no valid DoE model but displayed similar substrate scope. High specific activity and excellent radiochemical yields with various pseudohalides (81-91%) suggest that the proposed radiofluorination methodology can complement the current [(18)F]KF/Kryptofix methods, particularly in the areas for which nonpolar reaction conditions are required. 相似文献
6.
K. Schramm-Nielsen J. Merry B. A. Nyeland N. H. Spliid H. Spliid 《Fresenius' Journal of Analytical Chemistry》1998,361(5):404-409
21 laboratories participated in the certification of a multicomponent ampouled reference material containing 24 pesticides.
This paper describes the statistical analysis of the unbalanced data set returned by the participants in the certification.
The simplest method of certification is achieved when laboratories report all the required data. In practice, however, with
complex analytical methods such as multicomponent analyses of organic compounds, laboratories are not able to report all the
required data. The response for each determinand in the material has been modelled in a three-factor nested model. For computational
comfort the model has been rephrased into a general linear model. The statistical problems with unbalanced data are discussed
in relation to ISO 5725 and ISO Guide 35. Tests for homogeneity are exact and uninfluenced by the unbalance in data. Unbalanced
data cause dependencies between mean squares above the second lowest level of the model, thus exact hypothesis testing is
not possible at higher levels. Approximate tests for variation between rounds and laboratories has been constructed by means
of Satterthwaite’s formula [1]. A graphical plot of deviances from certified values has been applied to illustrate laboratory
performance.
Received: 25 May 1997 / Revised: 6 December 1997 / Accepted: 15 January 1998 相似文献
7.
8.
Erwin A. J. M. Bente Yohan Barbarin Martijn J. R. Heck Meint K. Smit 《Optical and Quantum Electronics》2008,40(2-4):131-148
In this paper a model and simulation results of integrated semiconductor passively modelocked ring lasers are presented. The model includes nonlinear effects such as two-photon absorption and a non-linear refractive index, a logarithmic gain-carrier relation, and concentration dependent radiative and non-radiative carrier recombination rates. The optical bandwidth of the system is controlled by a digital filter. The model has been used to simulate two geometries of ring modelocked lasers. The first is a symmetric design, where the two counter propagating pulses in the cavity experience the same amplification and absorption. The second is an asymmetric design where the differences for the two directions of pulse propagation are maximised. Simulation results show that a symmetrical cavity shows a several times wider window for its operating parameters for stable modelocking. 相似文献
9.
Christensen AN Jensen TR Lebech B Hanson JC Jakobsen HJ Skibsted J 《Dalton transactions (Cambridge, England : 2003)》2008,(4):455-462
The stability of monocalcium aluminate decahydrate, with the nominal composition CaAl(2)O(4).10H(2)O (CAH(10)), has a decisive role for the strength development and durability of cementitious materials based on high alumina cements. This has prompted an investigation of the thermal transformation of crystalline monocalcium aluminate decahydrate in air to an amorphous phase by in-situ synchrotron X-ray powder diffraction in the temperature range from 25 to 500 degrees C, by DTA/TGA, and (2)H, (27)Al MAS NMR spectroscopy. The decomposition includes the loss of hydrogen-bonded water molecules in the temperature range up to 175 degrees C, coupled with a reduction of the unit cell volume from 1928 A(3) at 25 degrees C, to 1674 A(3) at 185 degrees C. Furthermore, X-ray diffraction shows that CaAl(2)O(4).10H(2)O starts to transform to an amorphous phase at approximately 65 degrees C. This phase is fully developed at approximately 175 degrees C and it converts to crystalline CaAl(2)O(4) when heated to 1300 degrees C. The thermal decomposition in the temperature range from approximately 65 to approximately 175 degrees C involves both formation of an amorphous phase including AlO(4) tetrahedra and structural changes in the remaining crystalline phase. 相似文献
10.
B.?W.?Tilma M.?S.?Tahvili J.?Kotani R.?N?tzel M.?K.?Smit E.?A.?J.?M.?Bente 《Optical and Quantum Electronics》2009,41(10):735-749
Small signal modal gain measurements have been performed on two-section ridge waveguide InAs/InP (100) quantum-dot amplifiers
that we have fabricated with a peak gain wavelength around 1.70 μm. The amplifier structure is suitable for monolithic active-passive
integration, and the wavelength region and wide gain bandwidth are of interest for integrated devices in biophotonic applications.
A 65 nm blue shift of the peak wavelength in the gain spectrum has been observed with an increase in injection current density
from 1,000 to 3,000 A/cm2. The quantum-dot amplifier gain spectra have been analyzed using a quantum-dot rate-equation model that considers only the
carrier dynamics. The comparison between measured and simulated spectra shows that two effects in the quantum-dot material
introduce this large blue shift in the gain spectrum. The first effect is the carrier concentration dependent state filling
with carriers of the bound excited and ground states in the dots. The second effect is the decrease in carrier escape time
from the dots to the wetting layer with decreasing dot size. 相似文献