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71.
Levels of 13 pesticides in 40 honey samples form Poland are reported. A rapid and sensitive method was developed for the LC-ESI-MS/MS determination of multi-class pesticide residues in honey samples. Liquid–liquid extraction (LLE) on a diatomaceous earth support (requiring the use of small amounts of organic solvent), followed by chromatographic separation on a C18 column and gradient elution were employed. The method quantifies over a dynamic linear range from respective MQLs (0.06–1.3 ng/g) to 5 ng/g. Matrix effects were evaluated by comparing the slopes of matrix-matched and solvent-based calibration curves. The mean recoveries obtained for three fortification levels (0.5, 1.0 and 4.0 ng/g) were 63–117% for most compounds, with an expanded uncertainty of <10%. The results for real honey samples collected from five regions of Poland (Pomerania, Wielkopolska, Lublin Region, Lower and Upper Silesia), showed that residue concentrations were <5 ng/g and did not pose a threat to human health. 相似文献
72.
Arun K. Sharma Jacek Krzeminski Dhimant Desai Shantu Amin 《Polycyclic Aromatic Compounds》2013,33(3):297-305
Syntheses of naphtho[8,1,2- ghi ]chrysene (naphtho[1,2- e ]pyrene, N[ e ]P) 1 , dibenzo[ c,mno ]chrysene (naphtho[1,2- a ]pyrene, N[ a ]P) 2 and their dihydrodiol metabolites are described. The hydrocarbons N[ e ]P 1 and N[ a ]P 2 and their fjord region dihydrodiols 12 and 19 were synthesized using a Suzuki cross-coupling reaction followed by the appropriate manipulation of the functional groups. The K-region cis dihydrodiols of N[ e ]P-4,5-diol 20 , N[ a ]P-4,5-diol 23 , N[ a ]P-7,8-diol 24 were obtained by OsO 4 oxidation. The cis diols thus obtained were first converted to the corresponding quinones with pyridinium chlorochromate and, finally, to the desired trans dihydrodiols 22 , 27 , and 28 by NaBH 4 reduction. The mixture of trans N[ a ]P-4,5- and 7,8-dihydrodiols was separated by high-performance liquid chromatography. 相似文献
73.
Andrzej Wrbel ukasz Zapaa Tomasz Kluz Artur Rogowski Marcin Misiek Kajetan Juszczak Jacek Sieko Daniela Gold Klaudia Stangel-Wjcikiewicz Ewa Poleszak Piotr Radziszewski 《International journal of molecular sciences》2021,22(11)
The purpose of this study was to determine if asiatic acid may act efficiently in the model of cyclophosphamide (CYP)-induced cystitis in rats. We performed experiments after administration of CYP (single dose 200 mg/kg, intraperitoneally), asiatic acid (30 mg/kg/day for 14 consecutive days, by oral gavage), or CYP plus asiatic acid, during which conscious cystometry, measurements of urothelium thickness and bladder edema, as well as selected biomarkers analyses were conducted. In rats that received asiatic acid together with CYP, a drop in bladder basal pressure, detrusor overactivity index, non-voiding contraction amplitude, non-voiding contraction frequency, and the area under the pressure curve were observed, when compared to the CYP group. Furthermore, a significant increase in threshold pressure, voided volume, intercontraction interval, bladder compliance, and volume threshold to elicit NVC were found in that group accordingly. Administration of the asiatic acid successfully restored concentrations of biomarkers both in bladder urothelium (BDNF, CGRP, OCT-3, IL-1β, IL-6, NGF, nitrotyrosine, malondialdehyde, TNF-α, SV2A, SNAP23, SNAP25, PAC-1, ORM1, occludin, IGFBP-3, HB-EGF, T–H protein, Z01, and HPX) and detrusor muscle (Rho kinase and VAChT) in CYP-treated rats. Finally, asiatic acid significantly decreased urothelium thickness and bladder oedema. Asiatic acid proved to be a potent and effective drug in the rat model of CYP-induced cystitis. 相似文献
74.
Jacek Sroka Jan Hidders Paolo Missier Carole Goble 《Journal of Computer and System Sciences》2010,76(6):490-508
This paper presents a formal semantics for the Taverna 2 scientific workflow system. Taverna 2 is a successor to Taverna, an open-source workflow system broadly adopted within the e-science community worldwide. The new version improves upon the existing model in two main ways: (i) by adding support for data pipelining, which in turns enables input streams of indefinite length to be processed efficiently; and (ii) by providing new extensibility points that make it possible to add new operators to the workflow model. Consistent with previous work by some of the authors, we use trace semantics to describe the effect of workflow computations, and we show how they can be used to describe the new features in the Taverna 2 model. 相似文献
75.
76.
Jacek Slowik Günter Borchardt Christian Khler Rudolf Jeschar Reinhard Scholz 《国际钢铁研究》1990,61(7):302-311
In order to model heat transfer from the slab to the cooling agent in the continuous casting process the thermophysical properties of the surface layer must be taken into account. For this purpose thermal conductivities and thermal diffusivities of wustite as well as of two carbon steels were measured. The oxide scale growth for six steels was measured as a function of time and at temperatures between 900 and 1200°C in air and in steam. Complex heterogeneous oxide scales were examined by optical and scanning electron microscopy, by SIMS, as well as by Mössbauer spectroscopy. Segregation of alloying elements in the metal-oxide contact zone was found. Cracks due to thermal stresses result in spalling of the scale. Therefore, a straightforward use of the data for process modelling can principally not be recommended without restrictions. 相似文献
77.
Jacek Biesiada Janusz Zieliński 《Journal of Superconductivity and Novel Magnetism》1997,10(5):513-517
The anisotropic superconductivity has been considered in the two-dimensional Hubbard model. We allow for on and off-site intralayer
Cooper pairs. Interlayer momentum-conserving Josephson tunneling which couples adjacent layers has been taken into account.
The meanfield solution for the superconducting transition temperature demonstrates the competition between local Coulomb repulsion
and interlayer tunneling in thes-wave channel. This competition leads to the mixedsd superconducting state at low doping. We also demonstrate thatc-phonon-assisted transitions between intra and interlayer states can effectively give rise to momentum-conserving Josephson
tunneling. 相似文献
78.
Some aspects of the generation and detection of ultrasound with laser beams are presented. The objective of the study is (1) to present some experimental results on the generation of ultrasound with an array of optical fibers, (2) to discuss the possibility of generating directional surface waves with acousto-optic scanning in a very narrow frequency band, thus increasing the signal-to-noise ratio, and (3) to discuss the feasibility of the directional detection of ultrasound by using an array of optical fibers as a receiver, also with the goal of increasing the signal-to-noise ratio. 相似文献
79.
Jacek Pigowski 《大分子材料与工程》1985,136(1):129-134
The thermal dependence of the surface tension of poly(vinyl chloride) (PVC) containing typical additives was determined below the glass transition temperature. From the results, the surface tension of PVC melts was evaluated and possible differences between the real value and estimate are discussed. It is suggested that the surface tension does not affect the wall-slipping properties of PVC melts. 相似文献
80.
In this paper the embedding of gold clusters in crystallizing bisphenol-A polycarbonate is treated as diffusion with drift in inhomogeneous and changing in time medium. Initially the gold is deposited on the polymer surface, which is subsequently exposed to acetone vapour. The polymer undergoes significant crystallization, induced by diffusing agent, while gold clusters become embedded in its bulk. The paper presents a model of gold dispersion based on Smoluchowski equation. It identifies the driving force of dispersion with the gradient of stress field generated during crystallization. Numerical results of the model are found to be in good agreement with available experimental data obtained by XPS depth profiling technique. 相似文献