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61.
Shiva Agarwal M. Teresa A. Reis M. Joana Neiva Correia Jorge M. R. Carvalho 《溶剂提取与离子交换》2013,31(5):536-551
The extraction equilibrium of copper from sulfate media with the aldoxime Acorga M5640 in ShellSol D70 has been investigated. The distribution results were interpreted by taking into account the nonideality of the aqueous phase. The activity of copper and hydrogen ions in the target systems CuSO4/H2SO4/Na2SO4 and CuSO4/H2SO4/Fe2(SO4)3/ZnSO4 were calculated through the speciation of the aqueous solutions and by applying the Pitzer model. The experimental pH values were found in good agreement with the predicted pH values. A model considering the dimerization of the aldoxime extractant was proposed to predict the distribution ratio and the copper loading isotherms. The extraction constant at infinite dilution and the apparent dimerization constant were evaluated from the experimental data and were found to be 103.06 ± 0.07 and 51 ± 9 M?1, respectively, at 25°C. 相似文献
62.
The hitherto unknown 2-methylsulfanyldecanoic acid and 2-methylsulfanyldodecanoic acid were synthesized from methyl decanoate
and methyl dodecanoate, respectively, through the reaction of lithium diisopropylamide and dimethyldisulfide in THF followed
by saponification with potassium hydroxide in ethanol. Both α-methylsulfanylated FA were cytotoxic to the human chronic myelogenous
leukemia K-562 and the human histiocytic lymphoma U-937 cell lines with EC50 values in the 200–300 μM range, which makes them more cytotoxic to these cell lines than decanoic and/or dodecanoic acid.
The cytotoxicity of the studied FA toward K-562 followed the order 2-SCH3-12∶0>2-SCH3-10∶0>10∶0>12∶0>2-OCH3-12∶0, whereas toward U-937 the cytotoxicity was 2-SCH3-10∶0>2-SCH3-12∶0>12∶0>10∶0>2-OCH3-12∶0. These results indicate that the α-methylsulfanyl substitution increases the cytotoxicity of the C10 and C12 FA toward the studied leukemia cell lines. 相似文献
63.
Ignacio Moreno‐Villoslada Felipe Oyarzún Víctor Miranda Susan Hess Bernab L. Rivas 《应用聚合物科学杂志》2005,98(2):598-602
The binding of cationic chlorpheniramine maleate (CPM) to the anionic water‐soluble polymers (WSPs) alginic acid, carboxymethylcellulose, κ‐carageenan, and ι‐carageenan was evaluated by diafiltration at pH 7.5 and in the absence and presence of 0.13M NaCl. CPM interacted with all of the WSPs when no NaCl was present in the solution, with charge‐related formation constants of around 700 M?1 for all of the polymers, whereas the interactions were cleaved in the presence of 0.13M NaCl, indicating interactions of an electrostatic nature screened by the single electrolyte. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 598–602, 2005 相似文献
64.
A systematic comparison of PCA‐based Statistical Process Monitoring methods for high‐dimensional,time‐dependent Processes 下载免费PDF全文
Tiago Rato Marco Reis Eric Schmitt Mia Hubert Bart De Ketelaere 《American Institute of Chemical Engineers》2016,62(5):1478-1493
High‐dimensional and time‐dependent data pose significant challenges to Statistical Process Monitoring. Most of the high‐dimensional methodologies to cope with these challenges rely on some form of Principal Component Analysis (PCA) model, usually classified as nonadaptive and adaptive. Nonadaptive methods include the static PCA approach and Dynamic Principal Component Analysis (DPCA) for data with autocorrelation. Methods, such as DPCA with Decorrelated Residuals, extend DPCA to further reduce the effects of autocorrelation and cross‐correlation on the monitoring statistics. Recursive Principal Component Analysis and Moving Window Principal Component Analysis, developed for nonstationary data, are adaptive. These fundamental methods will be systematically compared on high‐dimensional, time‐dependent processes (including the Tennessee Eastman benchmark process) to provide practitioners with guidelines for appropriate monitoring strategies and a sense of how they can be expected to perform. The selection of parameter values for the different methods is also discussed. Finally, the relevant challenges of modeling time‐dependent data are discussed, and areas of possible further research are highlighted. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1478–1493, 2016 相似文献
65.
Sustained release of potassium diclofenac from a pH‐responsive hydrogel based on gum arabic conjugates into simulated intestinal fluid 下载免费PDF全文
Adriano V. Reis Thais A. Moia Danielly L. A. Sitta Marcos R. Mauricio Ernandes T. Tenório‐Neto Marcos R. Guilherme Adley F. Rubira Edvani C. Muniz 《应用聚合物科学杂志》2016,133(16)
This work describes the preparation, the swelling properties and the potassium diclofenac (KDF) release profile of hydrogels of gum arabic (GA), N′,N′‐dimethylacrylamide, and methacrylic acid. In order to convert GA into a hydrogel, the polysaccharide was vinyl‐modified with glycidyl methacrylate. The hydrogels showed pH‐responsive swelling changes, which were more expressive in the basic environment. Release data of KDF were adjusted to a diffusion‐based kinetic model that provides an important insight on affinity of the drug for hydrogel and solvent, which may be the leading parameter for release of guest molecules from polymers. The KDF release from the hydrogels into simulated intestinal fluid decreases when the amount of modified GA increases. This was demonstrated to be due to the higher affinity of KDF for GA‐richer hydrogel, which makes the anti‐inflammatory release less favorable. The analysis of released drug half‐time (t1/2 = 16.10 and 21.51 h) indicated sustained release characteristics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43319. 相似文献
66.
67.
Córdova MO Flores Ramírez CI Bejarano BV Arroyo Razo GA Pérez Flores FJ Tellez VC Ruvalcaba RM 《International journal of molecular sciences》2011,12(12):8575-8580
In this work, the results of a study comparing the use of irradiation from different regions of the infrared spectrum for the promotion of several organic reactions, are presented and discussed. This use of eco-conditions provides a green approach to chemical synthesis. A set of ten different organic reactions were evaluated, including the Knoevenagel, Hantzsch, Biginelli and Meldrum reactions. It is important to highlight the use of a commercial device that produces infrared irradiation in the near infrared region and its distribution by convection providing heating uniformity, significantly reducing reaction times, achieving good yields and proceeding in the absence of solvent. It is also worth noting that a variety of different reactions may be performed at the same time. Finally, the products obtained were identified using TLC, together with corresponding MS-data, complementarily in comparison of NMR (1)H and (13)C data with literature information. 相似文献
68.
Claudia F. Galinha Gilda Carvalho Carla A. M. Portugal Giuseppe Guglielmi Maria A. M. Reis João G. Crespo 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(7):985-992
BACKGROUND: The use of two‐dimensional (2D) fluorescence for monitoring complex biological systems requires careful assessment of the effect of chemical species present, which may be fluorescent and/or may interfere with the fluorescence response of target fluorophores. Given the complexity of fluorescence data (excitation emission matrices—EEMs), the challenge is how to recover the information embedded into those EEMs that can be related quantitatively with the observed performance of the biological processes under study. RESULTS: This work shows clearly that interference effects (such as quenching and inner filter effects) occur due to the presence of multiple species in complex biological media, such as natural water matrices, wastewaters and activated sludge. A statistical multivariate analysis is proposed to recover quantitative information from 2D fluorescence data, correlating EEMs with the observed performance. A selected case study is discussed, where 2D fluorescence spectra obtained from the effluent of a membrane bioreactor were compressed using PARAFAC and successfully correlated with the effluent chemical oxygen demand, using projection to latent structures modelling. CONCLUSION: This study demonstrates the potential of using 2D fluorescence spectroscopy as a status fingerprint. Additionally, it is shown how statistical multivariate data analysis can be used to correlate EEMs with selected performance parameters for monitoring of biological systems. Copyright © 2011 Society of Chemical Industry 相似文献
69.
J. Miranda P. Partal F. Cordobes A. Guerrero 《Journal of the American Oil Chemists' Society》2002,79(2):183-190
The present work studies the rheological properties of avian egg yolks processed by spray-drying and by lipid-cholesterol
extraction with CO2 under near-critical conditions. The results have been compared with those obtained from native egg products in order to analyze
the effect of processing on the microstructure and rheological properties of egg yolks. The rheological study included linear
viscoelasticity measurements by means of dynamic oscillatory shear and creep tests, which provided information about the unperturbed
structure of the material, as well as steady-state flow measurements. The thermal denaturation of proteins, which was produced
during the spray-drying of egg yolk, was responsible for the dramatic change from fluid to gel-like behavior. The thermal
denaturation of proteins promotes the formation of a gel-like network, which may be attributed to exposure of internal hydrophobic
groups that favor protein aggregation. Lipid (and cholesterol) extraction from yolk increased the viscoelasticity functions
and flow properties due to the increased protein concentration. 相似文献
70.
Paulo A.N. Dias José A.C. Alves Duncan Paul Fagg Marco S. Reis Maria H. Gil 《乙烯基与添加剂工艺杂志》2012,18(2):95-104
A new material has been developed consisting of pieces of wood embedded within a matrix of acrylic polymer, resulting in a transparent or semitransparent wood‐based product. This material presents quite appealing aesthetic features, thereby opening new possibilities for decorative applications. Because acrylic and methacrylic monomers are in the liquid state at room temperature, it is possible to introduce wood (in the current case, walnut wood) into a mixture of acrylic (hydroxypropyl acrylate) and/or methacrylic monomers (methyl methacrylate and 2‐hydroxyethyl methacrylate) along with a plasticizer (dioctyl phthalate) in the presence of a chemical initiator (benzoyl peroxide). A transparent polymeric matrix with dispersed wood is then obtained through bulk free‐radical polymerization. Introducing this reaction mixture along with pieces of wood into a mold results in a wood‐polymer composite. A 24?1 experimental fractional factorial design was implemented to study the importance of the composition of these materials on several relevant properties. The sheets produced were characterized by tensile testing, dynamic mechanical thermal analysis, thermal gravimetric analysis, and heat deflection temperature. The models obtained for predicting each property pointed to valuable insights regarding the influential constituents. In particular, our results suggested that monomers to be used in future applications of this material should be selected in terms of their cost and the desired flexibility for the final product, not in terms of their polarity. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers 相似文献