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排序方式: 共有84条查询结果,搜索用时 31 毫秒
51.
Jorge Núez-Morales Lorena I. Jaramillo Patricio J. Espinoza-Montero Vanessa E. Snchez-Moreno 《Molecules (Basel, Switzerland)》2022,27(7)
The production and use of eco-friendly corrosion inhibitors allows valuable compounds contained in plant waste to be identified and repurposed while reducing the use of polluting synthetic substances. Pectin extracted from Tahiti limes (Citrus latifolia) and King mandarin (Citrus nobilis L.) in addition to natural gums—xanthan gum and latex from the “lechero” plant (Euphorbia laurifolia)—were used to create an eco-friendly corrosion inhibitor. The optimal extraction conditions for pectin were determined from different combinations of pH, temperature, and time in a 23 factorial design and evaluated according to the obtained pectin yield. The highest pectin extraction yields (38.10% and 41.20% from King mandarin and lime, respectively) were reached at pH = 1, 85 °C, and 2 h. Extraction of pectic compounds was confirmed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analyses. Subsequently, a simplex-centroid mixture design was applied to determine the formulation of extracted pectin and natural gums that achieved the highest corrosion inhibitor effect (linear polarization and weight loss methods in NACE 1D-196 saline media using API-5LX52 carbon steel). Impedance spectroscopy analysis showed that the addition of xanthan gum to pectin (formulation 50% pectin–50% xanthan gum) improved the corrosion inhibitor effect from 29.20 to 78.21% at 400 ppm due to higher adsorption of inhibitory molecules on the metal surface. 相似文献
52.
We assess the performance of the Van Voorhis–Scuseria exchange–correlation functional (VSXC), a kinetic-energy-density-dependent
exchange–correlation functional recently developed in our group, for calculating vertical excitation energies using time-dependent
density functional theory in a benchmark set of molecules. Overall, VSXC performs very well, with accuracy similar to that of hybrid functionals such as the hybrid Perdew–Burke–Ernzerhof functional
and Becke's three parameter hybrid method with the Lee, Yang, and Parr correlation functional, which contain a portion of
Hartree–Fock exchange.
Received: 29 December 1999 / Accepted: 5 June 2000 / Published online: 11 September 2000 相似文献
53.
In this note we prove that the uniformity of a complete metric space X is characterized by the vector lattice structure of the set U(X) of all uniformly continuous real functions on X. 相似文献
54.
Preparation and ozone-surface modification of activated carbon. Thermal stability of oxygen surface groups 总被引:1,自引:0,他引:1
The control of the surface chemistry of activated carbon by ozone and heat treatment is investigated. Using cherry stones, activated carbons were prepared by carbonization at 900 °C and activation in CO2 or steam at 850 °C. The obtained products were ozone-treated at room temperature. After their thermogravimetric analysis, the samples were heat-treated to 300, 500, 700 or 900 °C. The textural characterization was carried out by N2 adsorption at 77 K, mercury porosimetry, and density measurements. The surface analysis was performed by the Bohem method and pH of the point of zero charge (pHpzc). It has been found that the treatment of activated carbon with ozone combined with heat treatment enables one to control the acidic-basic character and strength of the carbon surface. Whereas the treatment with ozone yields acidic carbons, carbon dioxide and steam activations of the carbonized product and the heat treatment of the ozone-treated products result in basic carbons; the strength of a base which increases with the increasing heat treatment temperature. pHpzc ranges between 3.6 and 10.3. 相似文献
55.
The magnitude of an electric dipole moment must be larger or equal to a certain value to support bound states. Such critical dipole moment, pcrit, has been calculated in 2 and 3 dimensions and has been suggested that its calculation in one dimension cannot be possible. We evaluate pcrit in one dimension showing that the previous suggestion is untenable. 相似文献
56.
57.
Using a standardized miniature format ion selective electrode, five different carbon based solid contact materials, including a novel commercially available graphene oxide assisted carbon nanotube dispersion (FlexipheneTM), were compared. The electromotive force (EMF) response, stability, and behavior following storage was evaluated. Bulk resistance for the novel graphene oxide/carbon nanotube (GO‐CNT) based ISE was observed to be 0.09±0.03 MΩ, which is two orders of magnitude lower than reported for either component in isolation. The results for previously described solid contact materials are in general agreement with the literature, and the tradeoffs between solid contact layer material choices are discussed. Performance of GO‐CNT solid contact ion selective electrodes were then evaluated in a 3D‐printed fluidic array to determine their suitability for future in situ instruments. 相似文献
58.
Karlberg GS Jaramillo TF Skúlason E Rossmeisl J Bligaard T Nørskov JK 《Physical review letters》2007,99(12):126101
Cyclic voltammetry is a fundamental experimental method for characterizing electrochemical surfaces. Despite its wide use, a way to quantitatively and directly relate cyclic voltammetry to ab initio calculations has been lacking. We derive the cyclic voltammogram for H on Pt(111) and Pt(100), based solely on density functional theory calculations and standard molecular tables. By relating the gas phase adsorption energy to the electrochemical electrode potential, we provide a direct link between surface science and electrochemistry. 相似文献
59.
Molybdenum Phosphosulfide: An Active,Acid‐Stable,Earth‐Abundant Catalyst for the Hydrogen Evolution Reaction 下载免费PDF全文
Dr. Jakob Kibsgaard Prof. Thomas F. Jaramillo 《Angewandte Chemie (International ed. in English)》2014,53(52):14433-14437
Introducing sulfur into the surface of molybdenum phosphide (MoP) produces a molybdenum phosphosulfide (MoP|S) catalyst with superb activity and stability for the hydrogen evolution reaction (HER) in acidic environments. The MoP|S catalyst reported herein exhibits one of the highest HER activities of any non‐noble‐metal electrocatalyst investigated in strong acid, while remaining perfectly stable in accelerated durability testing. Whereas mixed‐metal alloy catalysts are well‐known, MoP|S represents a more uncommon mixed‐anion catalyst where synergistic effects between sulfur and phosphorus produce a high‐surface‐area electrode that is more active than those based on either the pure sulfide or the pure phosphide. The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water‐splitting cells. 相似文献
60.
In this note we prove that the uniformity of a complete metric space X is characterized by the vector lattice structure of the set U(X) of all uniformly continuous real functions on X.
(Received 3 March 2000; in revised form 29 June 2000) 相似文献