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1.
Prof. Ashok R. Patel Nick Cludts Mohd Dona Bin Sintang Benny Lewille Ans Lesaffer Prof. Koen Dewettinck 《Chemphyschem》2014,15(16):3435-3439
The preparation and characterization of oleogels structured by using a combination of a surface‐active and a non‐surface‐active polysaccharide through an emulsion‐templated approach is reported. Specifically, the oleogels were prepared by first formulating a concentrated oil‐in‐water emulsion, stabilized with a combination of cellulose derivatives and xanthan gum, followed by the selective evaporation of the continuous water phase to drive the network formation, resulting in an oleogel with a unique microstructure and interesting rheological properties, including a high gel strength, G′>4000 Pa, shear sensitivity, good thixotropic recovery, and good thermostability. 相似文献
2.
Jean-Philippe Basly Anséline Gradolatto Caroline Teyssier Naric Chantal Canivenc-Lavier 《Monatshefte für Chemie / Chemical Monthly》2003,134(3):355-359
Summary. A selective
column switching high performance liquid chromatographic method has been used for the simultaneous determination of apigenin
and metabolites in rat liver perfusate. This new method clearly separated apigenin and the metabolites with high resolution.
The structures of metabolites were proposed based on selective ion recording and full scan analysis by electrospray ionization
mass spectrometry.
Corresponding author. E-mail: basly@pharma.unilim.fr
Received May 15, 2002; accepted (revised) September 13, 2002 相似文献
3.
Influence of air oxidation on the surfactant-assisted purification of single-walled carbon nanotubes
Ansón-Casaos A González M González-Domínguez JM Martínez MT 《Langmuir : the ACS journal of surfaces and colloids》2011,27(11):7192-7198
Arc discharge single-walled carbon nanotube (SWCNT) soot was treated under different experimental conditions including gas- and liquid-phase oxidation, heat treatment in an inert gas, and hydrogen gasification. Afterward, the samples were dispersed in a surfactant and centrifuged at a moderately high speed. Near-infrared spectra of all the dispersions were compared with that of raw SWCNT soot. The relative intensity of SWCNT characteristic spectral bands strongly increased for air-oxidized samples after centrifugation, while it did not substantially change for samples oxidized with nitric acid or reduced with hydrogen. The relative SWCNT spectral intensity was associated to the sample purity through the so-called purity index, which was calculated from the S(22) band transition of semiconducting SWCNTs. Air-oxidized samples experienced a 7-fold increase in the purity index during centrifugation, while it increased by only 2-3 times for nonoxidized samples. Air oxidation specifically improves the preferential stability of SWCNTs over carbonaceous impurities in the dispersions, leading to the highest purity index values reported so far. 相似文献
4.
A generic strategy for the chiral separation of non-acidic pharmaceuticals was updated to complete an approach defined earlier. The selected chiral stationary phases are all polysaccharide selectors, chlorinated, and non-chlorinated, namely Lux(?) Amylose 2, Chiralcel(?) OD-RH, Lux(?) Cellulose 4, and Chiralpak(?) AD-RH. In this study, the screening step of a strategy defined earlier was updated and the optimization steps were re-evaluated for the applied chiral stationary phases. These screening and optimization conditions were studied by analyzing 20 pharmaceuticals at different organic modifier contents, temperatures, or applied voltages. The proposed chiral separation strategy was then evaluated with a test set of 19 non-acidic drugs. Seventeen compounds (89.5%) of the latter set could be resolved of which eight (42%) were baseline separated. The strategy thus proved to be applicable on compounds different from those used for its development. 相似文献
5.
Single-walled carbon nanotubes (SWCNTs) should constitute an important natural step towards the improvement of the analytical performance of microfluidic electrochemical sensing. SWCNTs inherently offer lower detection potentials, higher surfaces and better stability than the existing carbon electrodes. However, pristine SWCNTs contain some carbonaceous and metallic impurities that influence their electrochemical performance. Thus, an appropriate processing method is important for obtaining high purity SWCNTs for analytical applications. In this work, a set of 0.1 mg mL(-1) SWCNT dispersions with different degrees of purity and different dispersants (SDBS; pluronic F68 and DMF) was carefully characterized by near infrared (NIR) spectroscopy giving a Purity Index (NIR-PI) ranging from 0.039 to 0.310. The highest purity was obtained when air oxidized SWCNTs were dispersed in SDBS, followed by centrifugation. The SWCNT dispersions were utilized to modify microfluidic chip electrodes for the electrochemical sensing of dopamine and catechol. In comparison with non-SWCNT-based electrodes, the sample with the highest NIR-PI (0.310) exhibited the best analytical performance in terms of improved sensitivity (3-folds higher), very good signal-to-noise ratio, high resistance-to-fouling in terms of relative standard deviation (RSD 7%; n = 15), and enhanced resolution (2-folds higher). In addition, very well-defined concentration dependence was also obtained with excellent correlation coefficients (r ≥ 0.990). Likewise, a good analytical sensitivity, suitable detection limits (LODs) and a very good precision with independence of the concentration assayed (RSDs ≤ 5%) was achieved. These valuable features indicate the suitability of this material for quantitative analysis. NIR-PI and further TEM and XRD characterization demonstrated that the analytical response was driven and controlled by the high NIR-PI of the SWCNTs used. The significance of this work is the demonstration for the first time of the sensitivity-purity relationship in SWCNT microfluidic chips. A novel and valuable analytical tool for electrochemical sensing has been developed: SWCNTs with high purity and a rich surface chemistry with functional groups, both essential for analytical purposes. Also, this work helps to better understand the analytical potency of SWCNTs coupled to microfluidic chips and it opens new gates for using these unique dispersions in real-world applications. 相似文献
6.
7.
Carlos Ansótegui Ramón Béjar Cèsar Fernández Carla Gomes Carles Mateu 《Journal of Heuristics》2011,17(5):589-614
Sudoku problems are some of the most known and enjoyed pastimes, with a never diminishing popularity, but, for the last few
years those problems have gone from an entertainment to an interesting research area, a twofold interesting area, in fact.
On the one side Sudoku problems, being a variant of Gerechte Designs and Latin Squares, are being actively used for experimental
design, as in Bailey et al. (Am. Math. Mon. 115:383–404, 2008; J. Agron. Crop Sci. 165:121–130, 1990), Morgan (Latin squares and related experimental designs. Wiley, New York, 2008) and Vaughan (Electron. J. Comb. 16, 2009). On the other hand, Sudoku problems, as simple as they seem, are really hard structured combinatorial search problems, and
thanks to their characteristics and behavior, they can be used as benchmark problems for refining and testing solving algorithms
and approaches. Also, thanks to their high inner structure, their study can contribute more than studies of random problems
to our goal of solving real-world problems and applications and understanding problem characteristics that make them hard
to solve. In this work we use two techniques for solving and modeling Sudoku problems, namely, Constraint Satisfaction Problem
(CSP) and Satisfiability Problem (SAT) approaches. To this effect we define the Generalized Sudoku Problem (GSP), where regions
can be of rectangular shape, problems can be of any order, and solution existence is not guaranteed. With respect to the worst-case
complexity, we prove that GSP with block regions of m rows and n columns with m≠n is NP-complete. For studying the empirical hardness of GSP, we define a series of instance generators, that differ in the
balancing level they guarantee between the constraints of the problem, by finely controlling how the holes are distributed
in the cells of the GSP. Experimentally, we show that the more balanced are the constraints, the higher the complexity of
solving the GSP instances, and that GSP is harder than the Quasigroup Completion Problem (QCP), a problem generalized by GSP.
Finally, we provide a study of the correlation between backbone variables—variables with the same value in all the solutions
of an instance—and hardness of GSP. 相似文献
8.
Electrochemical Sensor for the Quantification of Dopamine Using Glassy Carbon Electrodes Modified with Single‐Wall Carbon Nanotubes Covalently Functionalized with Polylysine
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Alejandro Gutiérrez Aurélien Gasnier María L. Pedano Jose Miguel Gonzalez‐Dominguez Alejandro Ansón‐Casaos Javier Hernández‐Ferrer Laura Galicia María D. Rubianes María T. Martínez Gustavo A. Rivas 《Electroanalysis》2015,27(7):1565-1571
We report a dopamine electrochemical sensor based on the modification of glassy carbon electrodes (GCE) with polylysine‐functionalized single‐wall carbon nanotubes (SWCNT‐PLys). The resulting electrodes (GCE/SWCNT‐PLys) showed a significant improvement in the electrooxidation of dopamine with drastic decrease in the peak potentials separation and important enhancement in the associated currents. Dopamine was detected by differential pulse voltammetry‐adsorptive stripping with medium exchange at nanomolar levels even in the presence of high excess of ascorbic and uric acids. The sensor was successfully used for the quantification of dopamine in urine samples enriched with the neurotransmitter. 相似文献
9.
Dr. A. Ansón-Casaos C. Rubio-Muñoz Dr. J. Hernández-Ferrer A. Santidrian Dr. A. M. Benito Dr. W. K. Maser 《Chemphyschem》2019,20(6):838-847
The transfer of nanoscale properties from single-walled carbon nanotubes (SWCNTs) to macroscopic systems is a topic of intense research. In particular, inorganic composites of SWCNTs and metal oxide semiconductors are being investigated for applications in electronics, energy devices, photocatalysis, and electroanalysis. In this work, a commercial SWCNT material is separated into fractions containing different conformations. The liquid fractions show clear variations in their optical absorbance spectra, indicating differences in the metallic/semiconducting character and the diameter of the SWCNTs. Also, changes in the surface chemistry and the electrical resistance are evidenced in SWCNT solid films. The starting SWCNT sample and the fractions as well are used to prepare hybrid electrodes with titanium dioxide (SWCNT/TiO2). Raman spectroscopy reflects the optoelectronic properties of SWCNTs in the SWCNT/TiO2 electrodes, while the electrochemical behavior is studied by cyclic voltammetry. A selective development of charge transfer characteristics and double-layer behavior is achieved through the suitable choice of SWCNT fractions. 相似文献
10.
Hydrogen capacity of palladium-loaded carbon materials 总被引:2,自引:0,他引:2
Ansón A Lafuente E Urriolabeitia E Navarro R Benito AM Maser WK Martínez MT 《The journal of physical chemistry. B》2006,110(13):6643-6648
Several samples of palladium-loaded single-wall carbon nanotubes and palladium-loaded MAXSORB activated carbon were prepared by means of the reaction of the raw carbon support with Pd2(dba)3.CHCl3. When carbon nanotubes were used as the support, the palladium content in the samples reached 13-31 wt % and fine particles of 5-7 nm average size were obtained. In the case of the samples with MAXSORB as the support, the palladium content was higher (30-50 wt %) and the particle size larger (32-42 nm) than in the nanotube samples. At 1 atm and room temperature, the hydrogen capacity of the palladium-loaded samples exceeds 0.1 wt % and is much higher than the capacity of the raw carbon supports (less than 0.01 wt %). The maximum hydrogen capacity at 1 atm and room temperature was found to be 0.5 wt %. A maximum hydrogen capacity of 0.7 wt % was obtained at 90 bar in a palladium-loaded MAXSORB sample, while the capacities for the raw carbon nanotubes and MAXSORB at the same pressure were 0.21 and 0.42 wt %, respectively. At low pressure, it was observed that the H/Pd atomic ratios in the palladium-loaded samples were always higher than in the bulk Pd. The spillover effect is considered as a possible cause of the high H/Pd atomic ratios. On the other hand, the effect of the pressure increase on the spillover was observed to be very low at high pressure and room temperature. 相似文献