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141.
E. García-Pérez J. B. Parra C. O. Ania A. García-Sánchez J. M. van Baten R. Krishna D. Dubbeldam S. Calero 《Adsorption》2007,13(5-6):469-476
The adsorption properties of CO2, N2 and CH4 in all-silica zeolites were studied using molecular simulations. Adsorption isotherms for single components in MFI were both
measured and computed showing good agreement. In addition simulations in other all silica structures were performed for a
wide range of pressures and temperatures and for single components as well as binary and ternary mixtures with varying bulk
compositions. The adsorption selectivity was analyzed for mixtures with bulk composition of 50:50 CO2/CH4, 50:50 CO2/N2, 10:90 CO2/N2 and 5:90:5 CO2/N2/CH4 in MFI, MOR, ISV, ITE, CHA and DDR showing high selectivity of adsorption of CO2 over N2 and CH4 that varies with the type of crystal and with the mixture bulk composition. 相似文献
142.
A comparative ab initio study was performed on the intramolecular proton-transfer reaction that occurs in alpha-hydroxyethanoxy, alpha-hydroxyphenoxide, and alpha-hydroxyethenoxy anions. The intramolecular proton transfer occurs in a five-member atom arrangement, between two oxygen atoms separated by a carbon-carbon bond. The chosen systems serve as models for alpha-hydroxyalkoxide molecules where the carbon-carbon bond varies from a single bond (the glycolate anion or alpha-hydroxyethanoxide anion) to a part of an aromatic ring (the alpha-hydroxyphenoxide anion), and finally to a double bond (the alpha-hydroxyethenoxide anion). Particular attention was given to the evolution along the intrinsic reaction coordinate of such properties as energies, relevant structural parameters, Mulliken charges, dipole moments, and 1H-NMR chemical shifts to reveal the similarities and differences for the proton transfer in the model systems. 相似文献
143.
J. Hernández-Méndez A.Alonso Mateos M.J.Almendral Parra C.García De María 《Analytica chimica acta》1986
A method is proposed for the flow-injection determination of ascorbic acid (0.1–40 μg ml?1). Iodine is generated in the flow system as triiodide ion or the triiodide/starch complex giving a steady spectrophotometric signal at 350 or 580 nm, respectively; inverse peaks caused by ascorbic acid samples are measured. The method is applied to the determination of ascorbic acid in a fruit juice, jam and vitamin C preparation. 相似文献
144.
Iron‐Catalyzed Stereoselective Cross‐Coupling Reactions of Stereodefined Enol Carbamates with Grignard Reagents
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Ana Cristina Parra Rivera Raymond Still Prof. Doug E. Frantz 《Angewandte Chemie (International ed. in English)》2016,55(23):6689-6693
A practical and highly stereoselective iron‐catalyzed cross‐coupling reaction of stereodefined enol carbamates and Grignard reagents to yield tri‐ and tetrasubstituted acrylates is reported. A facile method for the stereoselective generation of these enol carbamates has also been developed. 相似文献
145.
Andrea Gabriela Ochoa-Ruiz Guillermo Parra Diego López-Espinoza Pablo Astudillo Dmitry Galyamin Neus Sabaté Juan Pablo Esquivel Alba Adriana Vallejo-Cardona 《Electroanalysis》2023,35(4):e202200053
Electrochemical immunosensors comprise the merging of two different disciplines: molecular biology and electrochemistry. This review explains in depth the main parts of electrochemical immunosensors and how the enzyme-linked immunosorbent assay (ELISA) has been integrated into sophisticated “lab-on-a-chip” and “point-of-care” devices. It also reviews how nanotechnology has been a powerful tool for achieving lower detection limits, more signal amplification, and constructing label-free devices. It finally explores the new perspectives on electrochemical immunosensors to integrate them in novel paper microfluidic devices called EμPADs. Colleagues introducing themselves to the topic for the first time will find in this review a comprehensive revision of how the basics of the technology have given rise to the emerging topic of EμPADs. 相似文献
146.
The hydrophobic-hydrophilic character of a series of microporous activated carbons was explored as a key factor in competitive
adsorption of a non-polar compound from liquid phase. The selectivity of the carbon surface towards naphthalene was explored
by performing the adsorption isotherms in water, cyclohexane and heptane. Solvent polarity and adsorbent hydrophobic character
were found to strongly influence the adsorption capacity of naphthalene. In aqueous media, despite the non-polar character
of the adsorbate, surface acidity lowered adsorption capacity. This is attributed to the competition of water from the adsorption
sites, via H-bonding with surface functionalities and the formation of hydration clusters that reduce the accessibility and
affinity of naphthalene to the inner pore structure. In organic media the uptake decreased due to competition of the hydrophobic
solvent for the active sites of the carbon and to solvation effects. This competitive effect of the solvent is minimized in
oxidized carbons as opposed to the trend obtained in aqueous solutions. The results confirmed that although adsorption of
naphthalene strongly depends on the narrow microporosity of the adsorbent, competitive adsorption of the solvent for the active
sites becomes important. 相似文献
147.
148.
[Reaction: see text] A simple procedure to obtain N-sulfonyl imines involving the condensation of carbonyl compounds with p-tolyl or tert-butyl sulfinamides followed by oxidation with m-CPBA of the resulting N-sulfinylimines is reported. The method is applicable to aldehydes (aliphatics and aromatics) and ketones (diaryl, dialkyl, and aryl alkyl), even those containing enolizable protons. It also does not affect C=N or C=C double bonds and does not epimerize alpha-stereogenic centers. 相似文献
149.
M. J. Cánovas M. A. López J. Parra 《Journal of Optimization Theory and Applications》2005,125(2):275-297
In this paper, we propose a parametric approach to the stability theory for the solution set of a semi-infinite linear inequality system in the n-dimensional Euclidean space
. The main feature of this approach is that the coefficient perturbations are modeled through the so-called mapping of parametrized systems, which assigns to each parameter, ranging in a metric space, a subset of
. Each vector of this image set provides the coefficients of an inequality in
and the whole image set defines the inequality system associated with the parameter. Thus, systems associated with different parameters are not required to have the same number (cardinality) of inequalities. The paper is focused mainly on the structural stability of the feasible set mapping, providing a characterization of the Berge lower-semicontinuity property. The role played by the strong Slater qualification is analyzed in detail.This research has been partially supported by Grant PB98-0975 from DGES (Spain), Grant BFM2002-04114-C02 (01–02) from MCYT (Spain), FEDER (European Union), and Bancaja-UMH (Spain). 相似文献
150.
A nonlinear model of the evaporation of a pure volatile liquid is presented in which the moving liquid–vapour interface appears very naturally. The model gives the same results as an earlier linear formulation for the Stefan diffusion problem, but far more simply. 相似文献