排序方式: 共有36条查询结果,搜索用时 15 毫秒
1.
Churruca F SanMartin R Carril M Urtiaga MK Solans X Tellitu I Domínguez E 《The Journal of organic chemistry》2005,70(8):3178-3187
Novel dibenzo[a,c]phenanthridines are prepared regioselectively by the application of a straightforward synthetic pathway, starting from new 3,4-diaryl- and 3,4-dihydro-3,4-diarylisoquinolines prepared via Ritter-type heterocyclization and the more classical two-step reductive amination/Bischler-Napieralski cyclization of triarylethanones, respectively. A comparative study of nonphenolic oxidative coupling methodologies provides a highly efficient procedure, based on the hypervalent iodine reagent phenyliodine(III) bis(trifluoroacetate) (PIFA), to accomplish the final coupling step. 相似文献
2.
Jos M. Arandes Javier Erea Miren J. Azkoiti Martin Olazar Javier Bilbao 《Journal of Analytical and Applied Pyrolysis》2003,70(2):975-760
A study has been made of the cracking on a mesoporous silica of polystyrene (PS) and polystyrene-butadiene (PS-BD) dissolved in a light cycle oil (LCO) from a product stream of a commercial fluid catalytic cracking (FCC) unit. This study has been carried out in a reactor of short contact time (3 s) in the 723–823 K range. This strategy for simultaneous valorization of plastics and solvent avoids the technological problems inherent to the treatment of solid postconsumer-plastics and the limitation to heat transfer in the process of pyrolysis. The cracking of plastics has a synergistic effect on the conversion of LCO, as it contributes to increasing the yield of gasoline (C5–C12). The cracking of the PS/LCO blend produces high yields of styrene, whereas the cracking of the PS-BD/LCO blend produces a stream of products with petrochemical interest. 相似文献
3.
The use of proton nuclear magnetic resonance (1H-NMR) for the quantitation of additives in a commercial electrolytic nickel bath (Supreme Plus Brilliant, Atotech formulation)
is reported. A simple and quick method is described that needs only the separation of nickel ions by precipitation with NaOH.
The four additives in the bath (A-5(2X), leveler; Supreme Plus Brightener (SPB); SA-1, leveler; NPA, wetting agent; all of
them are commercial names from Atotech) can be quantified, whereas no other analytical methods have been found in the literature
for SA-1 and NPA. Two calibration methods have been tried: integration of NMR signals with the use of a proper internal standard
and partial least squares regression applied to the characteristic NMR peaks. The multivariate method was preferred because
of accuracy and precision. Multivariate limits of detection of about 4 mL L−1 A-5(2X), 0.4 mL L−1 SPB, 0.2 mL L−1 SA-1 and 0.6 mL L−1 NPA were found. The dynamic ranges are suitable to follow the concentration of additives in the bath along electrodeposition.
1H-NMR spectra provide evidence for SPB and SA-1 consumption (A-5(2X) and NPA keep unchanged along the process) and the growth
of some products from SA-1 degradation can be followed. The method can, probably, be extended to other electrolytic nickel
baths. 相似文献
4.
We study the forward problem of the magnetic Schrödinger operator with potentials that have a strong singularity at the origin. We obtain new resolvent estimates and give some applications on the spectral measure and on the solutions of the associated evolution problem. 相似文献
5.
Ainara Barriola José I. Miranda Miren Ostra Carlos Ubide 《Analytical and bioanalytical chemistry》2010,398(2):1085-1094
The use of proton nuclear magnetic resonance (1H-NMR) for the quantification of additives in an electrolytic Zn bath is reported. A simple and quick method is described
that does not need any prior sample preparation. Contrary to other analytical methods, the three additives in the bath, benzylidene
acetone (BDA), benzoic acid (BA) and poly(ethylene glycol) (PE400), can be quantified. Two calibration methods were tried:
integration of NMR signals with the use of an internal standard and partial least squares (PLS) regression applied to the
characteristic NMR peaks. Both methods are compared and the univariate method was preferred because of simplicity, accuracy
and precision. The following limits of detection were found: 0.30 g L−1 BA, 0.08 g L−1 BDA and 0.7 g L−1 PE400 with dynamic ranges of at least 1.0–6.0, 0.1–0.6 and 3.0–18.0 g L−1 respectively. Those concentration ranges are suitable to follow the concentration of additives in the bath in real time.
1H-NMR spectra provide evidence for the BDA degradation pattern. 相似文献
6.
Mira Petrovic Marinella Farré Miren Lopez de Alda Sandra Perez Cristina Postigo Marianne Köck Jelena Radjenovic Merixell Gros Damia Barcelo 《Journal of chromatography. A》2010,1217(25):4004-4017
An overview of liquid chromatography–mass spectrometry methods used for the determination of trace organic contaminants in environmental samples is presented. Among the organic contaminants the focus is given on five groups of emerging contaminants that raised most concern as environmental contaminants and therefore attracted attention of a research community: pharmaceuticals, drugs of abuse, polar pesticides, perfluorinated compounds and nanoparticles. Various aspects of current LC–MS methodology, using tandem and hybrid MS instruments, including sample preparation, are discussed. 相似文献
7.
Terrado M Kuster M Raldúa D Lopez de Alda M Barceló D Tauler R 《Analytical and bioanalytical chemistry》2007,387(4):1479-1488
Data sets obtained from quantitative analysis of seventeen pesticides in water samples from a network of irrigation and drainage
channels in the Ebro river delta (Catalonia, NE Spain) have been analysed by chemometric and geostatistical methods. Samples
were taken at fourteen locations during the main rice-growing season, from May to August 2005. Principal-component analysis
enabled investigation of the spatial and temporal distribution of the main pollution patterns caused by application of pesticides
in the region under study. A first pesticide-contamination pattern from the Ebro river was differentiated from a second more
specific pattern from the water-drainage channels of the delta, collected from the rice fields. The seasonal peak in this
more specific rice pesticide source was observed in July. Coupling the results from chemometric data analysis with use of
geostatistical methods was shown to be a useful procedure for discovery of the most significant spatial and monthly variations
of the main pesticide-contamination patterns, taking into account the particular geographical structure of the area under
study. 相似文献
8.
This study evaluates comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (GC×GC-ToF MS) for the simultaneous analysis of several classes of organobromines (OBs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), methoxylated PBDEs (MeO-PBDEs), several halogenated naturally produced compounds (HNPs) and eight novel brominated flame retardants (NBFRs), polybrominated hexahydroxanthene derivates (PBHDs), 2,4,6-tribromoanisole and a mixed halogenated compound (MHC-1), in bluefin tuna muscles. The proposed methodology maximised separation of both within and among OB families, and among these and other halogenated micropollutants detected in these samples and co-extracted matrix components. Special attention has been paid to solve co-elution problems observed during the analysis of OBs with one-dimensional GC-based techniques. Satisfactory separation among several relevant PBDEs and MeO-PBDEs has been obtained allowing their unambiguous determination in a single run. Additional studies were conducted to identify selected NBFRs and HNPs. 2,4-Dibromoanisole, a dibromophenol isomer and hexabromobenzene were identified in the investigated samples. Several new tri- and tetra-BHD derivates were also identified, indicating that these compounds could apparently exist as structured families in nature. In addition, a tetrabrominated diMeO-biphenyl and two tetrabrominated diMeO-BDEs were also tentatively identified. 相似文献
9.
Photocatalytic and magnetic titanium dioxide/polystyrene/magnetite composite hybrid polymer particles
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Audrey Bonnefond Miren Ibarra Edurne Gonzalez Mariano Barrado Andrey Chuvilin José Maria Asua Jose Ramon Leiza 《Journal of polymer science. Part A, Polymer chemistry》2016,54(20):3350-3356
Novel multifunctional titanium dioxide (TiO2)/polystyrene/magnetite composite hybrid polymer particle dispersions with TiO2 nanoparticles in the surface and magnetite nanoparticles encapsulated inside the polymer matrix were produced by Pickering miniemulsion polymerization in one single step. Whereas TiO2 nanoparticles were used to impart photocatalytic functionality and colloidal stability, magnetite nanoparticles were incorporated to allow an easy extraction for recovery and reuse of the composite multifunctional particles. The morphology of the composite particles was assessed by scanning transition electron microscopy (STEM) and energy‐dispersive X‐ray spectroscopy (EDX). The paramagnetism of the particles was analyzed using a SQUID magnetometer and their photocatalytic activity was assessed by degrading methylene blue (MB) solutions under UV light and by recovering and reusing of the particles in five consecutive cycles. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3350–3356 相似文献
10.
Monteserín Cristina Blanco Miren Laza Jose Manuel Aranzabe Estíbaliz Vilas Jose Luis 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1867-1881
Journal of Thermal Analysis and Calorimetry - A thermo-kinetic model was employed to study the temperature and curing degree distribution in a casting part of a DGEBA–DDM system during its... 相似文献