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131.
Analysis of application of Langmuir isotherm to heterogeneous systems: high-pressure conditions 总被引:2,自引:0,他引:2
Cordeiro CN da Rocha MS Faleiros AC Iha K 《Journal of colloid and interface science》2005,286(2):459-461
In this paper, an adsorption model that is based on the statistical mechanics approach was applied to study the saturation phenomena in adsorption to calculate the minimum pressure needed to attain the complete surface coverage on a physical adsorption. The fundamental integral equation, Theta(T)(Q)=integral N(Q)Theta(Q)dQ, for the calculation of the coverage degree of the surface was developed for an exponential distribution function, N(Q)=(m/RT)exp(-mQ/RT), and the representation of local adsorption sites is given by the Langmuir expression, Theta(Q)=b(0)C exp(Q/RT)/(1+b(0)C exp(Q/RT)). At high values of the pressure C, a solution of the fundamental integral equation was obtained by imposing the condition b(0)C>1. The expression for the saturation condition, b(0)C>m/(m+1), was obtained; that is, the saturation phenomenon is dependent on two parameters, correlated with the energetic heterogeneity and adsorption energy of the system. The pressure in the analysis of the cited expression shows that, for low m values (more heterogeneous systems), saturation is attained for b(0)C>m, while for m congruent with 1 (more homogeneous systems), the saturation is attained for b(0)C>0.5. 相似文献
132.
Interfacial properties and thermal stability of modified poly(m‐phenylene isophthalamide) thin films
Sandra Cruz dos Santos Lara Fernandes Loguercio Diogo Silva Corrêa Michael Ramos Nunes Marcos Antônio Villetti Irene Teresinha Santos Garcia 《Surface and interface analysis : SIA》2013,45(4):837-843
Poly(m‐phenylene isophthalamide) (PMIA) is a resistant to high temperatures and chemically stable engineering material. The application as coatings and membranes, however, is limited by its poor interaction with other materials. In this report, we describe the molecular modification of PMIA through reaction with dimsyl sodium and 2‐iodine‐1‐ethanol. The substitution of 58% of amide hydrogen by ethanol (etOH) groups produces a material (MPMIA) able to develop regularly structured films on silicon substrate. The morphology of the films is dependent on the ionic strength of the precursory solution. MPMIA starts a degradation process by losing the etOH group. MPMIA has a better affinity with poly(p‐cresolformaldehyde) than with a pristine one, increasing the range of composition in which thermal stability and miscibility are observed. Thin films of these blends have different morphologies that vary from nanometric porous to two‐phase microstructured grains, according to the composition. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
133.
Costa Renyer A. da Silva Jonathas Nunes Oliveira Kelson M. T. Dutra Lívia M. Costa Emmanoel V. 《Structural chemistry》2020,31(3):1223-1243
Structural Chemistry - Diterpenes are a class of secondary metabolites that attract much attention due to the numerous biological activities presented, such as antimicrobial, antiviral,... 相似文献
134.
Dobies Návia Marcos Vinícius Alves Gálico Diogo Junior Caires Flávio Marques Luiz José Spezia Nunes Ronaldo 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1717-1727
Journal of Thermal Analysis and Calorimetry - Solid-state [Ln(nal)3]·nH2O compounds, where Ln represents light trivalent lanthanide (La to Sm, except Pm), nal is nalidixate (C12H11N2O3), and n... 相似文献
135.
Fernandes Felipe Hugo Alencar Boylan Fabio Salgado Hérida Regina Nunes 《Journal of Thermal Analysis and Calorimetry》2018,132(3):1923-1931
Journal of Thermal Analysis and Calorimetry - The solid–liquid phase equilibrium for binary system of 2,4,6-trimethylphenol (TMP) and 2,5-dimethylphenol (DMP) was built by differential... 相似文献
136.
Helena H. Chubatsu Nunes Trinh-Don Nguyen Thu-Thuy T. Dang 《Current Opinion in Green and Sustainable Chemistry》2022
Many small-molecule chemicals from plants display extraordinarily complex structures and potent bioactivities with significant pharmacological and industrial implications. While the medicinal and economic relevance of plants' bioactive compounds is widely recognized, their industrial-scale chemical synthesis for distribution and development of new derivatives is hampered by challenges associated with their structural complexity. Extraction from the native plants is usually not viable due to the chemicals' low natural abundance, and the plants’ sub-optimal growing conditions due to climate change and the destruction of natural habitats. All of these challenges ultimately highlight the need to expand the (bio)chemical toolbox with strategies that support continuous discovery and sustainable production of relevant chemicals. This article highlights some of the most recent discoveries of plant-derived biocatalysts and how they pave the way for more sustainable and greener approaches to produce chemicals with unmatched complexity and applications. 相似文献
137.
Computational Management Science - In the application of machine learning to real-life decision-making systems, e.g., credit scoring and criminal justice, the prediction outcomes might discriminate... 相似文献
138.
Pedro Nunes Angelis Juliana Casarin Affonso Celso Gonçalves Júnior Luana Rianne Rocha Maiyara Carolyne Prete César Ricardo Teixeira Tarley 《Electroanalysis》2022,34(5):854-862
This paper reports the development of a simple electroanalytical method for imazethapyr (IMT) determination in rice samples based on molecularly imprinted polymer and functionalized carbon black paste electrode (MIP-fCBPE). Carbon black (CB) was functionalized by the insertion of oxygenated functional groups upon acid treatment with HNO3 and H2SO4. The functionalized carbon black (fCB) presented higher performance for IMT determination than the CB without functionalization. The insertion of molecularly imprinted polyvinylimidazole (MIP-VN) in the fCBPE promoted a significant increase in the cathodic peak current even at low proportions (7.5 % w/w) due to the specific binding sites for IMT recognition. For IMT determination, DPV parameters were optimized by the Doehlert matrix applying 0.1 V for 60 s as pre-treatment in acetate buffer solution (pH 3.0) as supporting electrolyte. The proposed method showed low limit of detection (0.03 μmol L−1), a wide linear range (0.10–70.00 μmol L−1), and good precision in terms of repeatability of intraday measures (RSD%=3.6). The method was applied in rice samples after microwave-assisted extraction of IMT and the accuracy of the method was evaluated by addition/recovery assays (96.3–105.7 %), being statistically attested using HPLC-DAD as reference technique. 相似文献
139.
140.
Palhares Hugo Guimarães Nunes Eduardo Henrique Martins Houmard Manuel 《Journal of Sol-Gel Science and Technology》2021,99(1):188-197
Journal of Sol-Gel Science and Technology - Most studies related to the synthesis of TiO2–SiO2 composites for photocatalytic applications did not systematically evaluate the textural and... 相似文献