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61.
Martín Caldera Villalobos Miriam Martins Alho Jesús García Serrano Giaan Arturo Álvarez Romero Ana M. Herrera González 《应用聚合物科学杂志》2019,136(29):47790
Heterocyclic compounds are well known for their biological activity and coordination properties. Some heterocyclic compounds have been employed in the stabilization against coalescence of metallic nanoparticles in colloidal solutions, for example, tetrazole, triazole, and pyrazole. The aim of this work is to design new polyelectrolytes with heterocyclic pendant groups useful as reducing agents of Au3+ and as stabilizing agents for the synthesis of colloidal Au nanoparticles. Thus, polyelectrolytes with thiosemicarbazone and 1,3,4-thiadiazole pendant groups were used as reducing agents of Au3+ ions and stabilizing agents of Au nanoparticles. The voltammetry study of the polyelectrolytes showed that one with thiosemicarbazone pendant groups is the better reducing agent than polyelectrolytes with heterocyclic pendant groups. The polyelectrolytes can control the growth of the nanoparticles, obtaining structures with an average size of 9 nm. In this study, it was concluded that the nature of the heterocyclic group does not have an effect on the shape of nanoparticles and quasi-spherical nanoparticles were obtained with all polyelectrolytes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47790. 相似文献
62.
Josiane Ferreira da Silva Débora Lemos da Silva Rui Gomes Nascimento Lizzy Ayra Alcântara Veríssimo Cristiane Martins Veloso Renata Cristina Ferreira Bonomo Rafael da Costa Ilhéu Fontan 《应用聚合物科学杂志》2019,136(37):47956
The use of macroporous monolithic matrices in the purification of biocompounds is constantly growing and developing. In this work, the objective was to optimize the quantity of N-acetyl-D-glucosamine (D-GlcNAc) immobilized on the surface of macroporous polymeric cryogels for capture of lectins from less clarified solutions. Surface response methodology was applied and it was observed that the immobilization temperature of the glutaraldehyde (GLU) and the D-GlcNAc concentration influenced the amount of sugar immobilized. The matrices produced with 1.1% of allyl glycidyl ether were functionalized by GLU. Optimal maximum condition was obtained with mean value of 160.39 ± 26.38 mg of D-GlcNAc immobilized per gram of dry cryogel. Characterization analyses of the matrices showed that the activation process was effective, maintaining the macroporous structure and physical characteristics. The adsorbents produced were tested for capture of lectins from a crude protein solution of barley. At tested conditions, adsorbent capture around 11% of protein in solution but reduce the hemaglutinating capacity in 40%, demonstrating its selectivity. The cryogels functionalized with D-GlcNAc present potential for use in capture compounds by affinity with carbohydrates, such as lectins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47956. 相似文献
63.
Clarissa P. Frizzo Mara R.B. Marzari Lilian Buriol Dayse N. Moreira Fernanda A. Rosa Pmela S. Vargas Nilo Zanatta Helio G. Bonacorso Marcos A.P. Martins 《Catalysis communications》2009,10(15):1967-1970
In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF4], [BMIM][Br], [OMIM][BF4], [BMIM][PF6], [DBMIM][Br], [DBMIM][BF4], [BMIM][OH], [BMIM][SCN], [HMIM][HSO4] and [HMIM][CF3CO2]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CHCHNMe2, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO2-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF4]. 相似文献
64.
Rui C. Martins 《臭氧:科学与工程》2009,31(5):402-411
Manganese-based catalysts supported on Al2O3, TiO2, ZrO2 and CeO2 were tested for the catalytic ozonation of a simulated wastewater involving phenolic acids. Comparing the Mn-Ce catalysts preparation method, wetness impregnation and co-precipitation, the last one showed to be more active. Moreover, the increase of Mn/Ce molar proportion from 22/78 to 70/30 increased the ozonation efficiency. The catalysts stability in terms of Mn leaching, carbon adsorption and effluent biodegradability was evaluated. Mn-Ce-O (70/30) CP shows to be the most suitable catalyst to improve phenolic wastewaters catalytic remediation by ozone. 相似文献
65.
The texture and surface acidic properties on niobium phosphate and its catalytic activities for isomerization of 1-butene, dehydration of 2-butanol and polymerization of propylene were studied as a function of pretreatment temperature. The surface of niobium phosphate showed strong acid sites of Ho - 8.2, for temperatures between 100 and 500°C; the acid sites were ascribed as Lewis and Bronsted sites on the basis of IR spectra of adsorbed pyridine. The activity for dehydration of 2-butanol was higher for samples pretreated at 150°C and activities for isomerization of 1-butene and polymerization of propylene were higher for samples pretreated at 250 and 300°C repectively. 相似文献
66.
67.
Danielle Q. Martins Wislei R. Osório Maria E.P. Souza Rubens Caram Amauri Garcia 《Electrochimica acta》2008,53(6):2809-2817
Titanium alloys show attractive properties for biomedical applications where the most important factors are biocompatibility, corrosion resistance, low modulus of elasticity, very good strength-to-weight ratio, reasonable formability and osseointegration. The aim of this study was to investigate the effects of Zr content (7.5 and 15 wt%) on microstructure and corrosion resistance of Ti–30Nb–Zr as-cast alloy samples. The corrosion tests were carried out in a 0.9% NaCl (0.15 mol L?1) solution at 25 °C and neutral pH range. A horizontal centrifuged solidification set-up was used to obtain as-cast samples with a fine dendritic arrangement. In order to evaluate the corrosion behavior, electrochemical impedance spectroscopy (EIS), polarization curves and an equivalent circuit analysis were used. It was found that the as-cast microstructure tends to have the dendrite arm spacings reduced with increasing Zr content. The results have shown that the addition of Zr to a Ti–30Nb alloy has been efficient to stabilize the beta phase. The resulting impedance parameters and passive current densities have shown that the Ti–30Nb alloys sample without Zr addition presents a higher surface reactivity which can induce a better osseointegration than those containing Zr. 相似文献
68.
Rosângela De A. Epifanio Danielle L. Martins Roberto Villaça Rebecca Gabriel 《Journal of chemical ecology》1999,25(10):2255-2265
The feeding-deterrence properties of crude extracts of three Brazilian octocoral species, Neospongodes atlantica Kükenthal (Alcyonacea, Nephtheidae), Plexaurella regia Castro (Gorgonacea, Plexauridae), and Phyllogorgia dilatata Esper (Gorgonacea, Gorgoniidae), were investigated. All the extracts were incorporated into food strips at the concentrations occurring in the living organisms. Crude extract and its ethyl acetate fraction obtained from P. dilatata collected in Armação dos Búzios (Rio de Janeiro State), when incorporated into artificial diets and tested in the habitat of origin, reduced consumption of food strips by fishes, relative to controls. Crude extracts from two octocoral species collected at the National Marine Park of Abrolhos (Bahia State), N. atlantica and P. regia, had no apparent feeding-deterrence properties; in fact, they seemed to stimulate feeding. Bioassay-guided fractionation of the bioactive P. dilatata crude extract revealed that the deterrent property was restricted to a medium polarity fraction. Field palatability experiments with two pure compounds isolated from this fraction revealed that the furanocembranolide 11,12-epoxypukalide is a potent feeding deterrent produced by P. dilatata against fish. Apparently, furanocembranolides are a particular class of compounds with feeding deterrent properties, protecting some octocorals from potential fish predator species in both tropical and temperate environments. 相似文献
69.
V. B. Martins T. P. Nagasima L. T. F. Eleno C. G. Schön 《Journal of Phase Equilibria and Diffusion》2017,38(3):195-200
The Pb–Bi (Lead–Bismuth) binary system has gained some prominence in recent years due to the possible use of eutectic alloys as primary-circuit coolant in generation IV nuclear reactors. Apart from the terminal solid solutions A1-Pb and A7-Bi, the system presents also one intermetallic phase with the hexagonal close-packed structure (A3), usually denoted ε phase. Due to the low temperatures involved in this system, attainment of equilibrium is difficult, and in addition, the proximity of x-ray scattering factors for both elements raises questions about a possible polymorphic transition. In the present work, three samples with compositions Pb–29 wt.%Bi, Pb–31 wt.%Bi and Pb–33 wt.%Bi were prepared and characterized by x-ray diffraction. The lattice parameters of ε are consistent with those reported in the literature, and their dependence on Bi content was determined as well. Only the hexagonal phase was identified in the 29 wt.%Bi sample, although the currently assessed Pb–Bi phase diagram predicts the presence of the Pb-rich A1 terminal solid solution in this composition. A 2-year annealing at room temperature was performed and the XRD characterization results for these samples are compared with the original data. 相似文献
70.
Janis Zicans Martins Kalnins Tatjana Ivanova Valdis Kalkis Andrzej K. Bledzki 《大分子材料与工程》1999,271(1):37-42
The present paper surveys the investigation results of the adhesive behavior with steel of different polyethylenes (LDPE, HDPE) irradiated with γ-radiation in vacuum, oxygen, and air, using rheological, optical, thermomechanical and other methods. To study the adhesive contact, the technological parameters applicable to thermosetting polymer material were taken into consideration. The results show the suitable methods in order to obtain thermosetting polymer materials with improved adhesive and thermomechanical properties. 相似文献