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71.
Gil Costa Machado Esther García-Tuñón Robert V. Bell Mauro Alini Eduardo Saiz Marianna Peroglio 《Journal of the European Ceramic Society》2018,38(3):949-961
Calcium phosphates (CaP) have been the subject of several studies that often lack a systematic approach to understanding how their properties affect biological response. CaP particles functionalised with a pH-responsive polymer (BCS) were used to prepare microporous substrates (porosity between 70 and 75% and pore sizes of 5–20 μm) through the aggregation of oil-in-water emulsions by controlling solid loading, emulsification energy, pH, drying and sintering conditions. The combined effect of surface roughness (roughness amplitude, Ra between 0.9–1.7 μm) and chemistry (varying Hydroxyapatite/β-Tricalcium phosphate ratio) on human mesenchymal stem cells was evaluated. HA substrates stimulated higher cell adhesion and proliferation (especially with lower Ra), but cell area increased with β-TCP content. The effect of surface roughness depended of chemistry: HA promoted higher mineralising activity when Ra ~ 1.5 μm, whereas β-TCP substrates stimulated a more osteogenic profile when Ra ~ 1.7 μm. A novel templating method to fabricate microporous CaP substrates was developed, opening possibilities for bone substitutes with controlled features. 相似文献
72.
Giovanna Grosso Martien A. Hulsen Arash Sarhangi Fard Andrew Overend Patrick D. Anderson 《American Institute of Chemical Engineers》2018,64(3):1034-1048
In many industrial applications, the quality of mixing between different materials is fundamental to guarantee the desired properties of products. However, properly modeling and understanding polymer mixing presents noticeable difficulties, because of the variety and complexity of the phenomena involved. This is also the case with the Cavity Transfer Mixer (CTM), an add‐on to be mounted downstream of existing extruders, to improve distributive mixing. The present work proposes a fully three‐dimensional model of the CTM: a finite element solver provides the transient velocity field, which is used in the mapping method implementation to compute the concentration field evolution and quantify mixing. Several simulations are run assessing the impact on mixing of geometrical and functioning parameters. In general, the number of cavities per row should be limited and the cavity size rather big to guarantee good mixing quality. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1034–1048, 2018 相似文献
73.
Synthesis and characterization of a new biobased poly(urethane‐ester) from ricinoleic acid and its use as biopolymeric matrix for magnetic nanocomposites 下载免费PDF全文
74.
Characterization of a water-based paint for corrosion protection 总被引:1,自引:0,他引:1
Paula Dias Catarina Carneiro Luísa Andrade José Sousa João Machado Adélio Mendes 《Journal of Coatings Technology and Research》2012,9(3):365-374
Corrosion of steel rebars in reinforced concrete is one of the major problems in the construction industry. Carbonation reactions of concrete with carbon dioxide and, mainly, the chloride salts action are the main causes responsible for concrete degradation. Protective coatings help to improve the durability of concrete structures by acting as a physical barrier against the corrosion agents. Waterborne paints are usually used for concrete protection rather than solvent-based paints since they are less pollutant. The aim of this work is to investigate the influence of the pore size and porosity on the permeability of the paints films toward sodium chloride. Three characterization methods from membrane science were implemented to characterize paint coatings. The time-lag method was used to determine the permeability toward the sodium chloride and toward helium and argon, these for approximately 100% relative humidity. From the seven waterborne paints formulated, only one was found to be suitable for surface protection of reinforced concrete, since its permeability toward NaCl was smaller than 10−14 m2 s−1, the threshold value required by National Laboratory of Civil Engineering (LNEC) in Portugal. For the formulated paints, it was observed that the average pore size correlates well with the permeability toward sodium chloride. This is an important result since obtaining the permeability toward sodium chloride of corrosion protective paints is very time consuming, while the average pore size can be obtained in a much shorter time. 相似文献
75.
Rodrigo Battisti Eduardo Hafemann Carlos Alberto Claumann Ricardo Antonio Francisco Machado Cintia Marangoni 《Polymer Engineering and Science》2019,59(5):891-898
This study provides a novel value‐added utilization of the agroindustrial waste of royal palm tree leaf sheath to produce cellulose acetate. One of the motivations of this work was the fact that Brazil is one of the largest heart of palm producers in the world. However, as a result of extraction and processing, tons of waste are generated and discharged to the environment. Such waste is rich in lignocellulosic material, which could be reused to obtain derivatives of interest and commercial value. The synthesis of cellulose acetate was performed through a homogeneous acetylation reaction. Three different conditions were tested for delignification of the raw material, which resulted in a reduction in lignin content from 17.75 to 7.72%. The highest yield of cellulose acetate reached 99.5%, with degree of substitutions ranging between 2.08 and 2.82, which indicates satisfactory conversion. The Fourier transform infrared spectrum showed that practically all hydroxyl groups were replaced by acetate groups; this was also confirmed by nuclear magnetic resonance analysis. X‐ray diffraction analysis showed that the cellulose acetate crystallinity index was 8.9%. This demonstrates the viable potential of cellulose acetate production with low cost and use of highly available agroindustrial waste. POLYM. ENG. SCI., 59:891–898, 2019. © 2018 Society of Plastics Engineers 相似文献
76.
Fatou Ndoye Muhammad Sulaiman Yousafzai Giovanna Coceano Serena Bonin Giacinto Scoles Oumar Ka 《International Journal of Optomechatronics》2016,10(1):53-62
We studied the lateral forces arising during the vertical indentation of the cell membrane by an optically trapped microbead, using back focal plane interferometry to determine force components in all directions. We analyzed the cell-microbead interaction and showed that indeed the force had also lateral components. Using the Hertz model, we calculated and compared the elastic moduli resulting from the total and vertical forces, showing that the differences are important and the total force should be considered. To confirm our results we analyzed cells from two breast cancer cell lines: MDA-MB-231 and HBL-100, known to have different cancer aggressiveness and hence stiffness. 相似文献
77.
Shaun?D.?Gittard Daisuke?Hojo G.?Kevin?Hyde Giovanna?Scarel Roger?J.?NarayanEmail author Gregory?N.?Parsons 《Journal of Materials Engineering and Performance》2010,19(3):368-373
The antifungal properties of two silver-coated natural cotton fiber structures prepared using a supercritical carbon dioxide
(scCO2) solvent were examined. Scanning electron microscopy confirmed that the scCO2 process may be used to produce cotton fiber textiles with uniform silver nanoparticle coatings. A version of the Kirby-Bauer
disk diffusion test was used to assess the ability of these textiles to inhibit fungal growth. Cotton fabric samples modified
with Ag(hepta) and Ag(cod)(hfac) exhibited measurable zones of inhibition. On the other hand, the uncoated fabric had no zone
of inhibition. Possible applications of antifungal textiles prepared using scCO2 processing include use in hospital uniforms and wound dressings. 相似文献
78.
Richard Thomas Lermen Ivan Guerra Machado 《Journal of Materials Processing Technology》2012,212(11):2371-2379
The main objectives of this study were to construct a plasma generator device and to investigate its applications in welding, cutting, and surface hardening. The device was derived from the union of two plasma-generating technologies, non-transferred-arc plasma and magnetoplasmadynamic thruster (MPDT), and characterised by the simultaneous formation of two plasma arcs in one device, generating a plasma jet with high energy density. Initially, trials were conducted to analyse the influence of the physical variables (gas flow rate and electric current intensities – primary and secondary) on the plasma jet, for which the thruster and the length of the plasma jet expulsed from the chamber were determined. The relevant parameters for welding, cutting and surface hardening were determined by trial and error, in which the trials were conducted using various plate thicknesses and materials. The results have shown that this device can be used for welding, cutting and surface hardening. 相似文献
79.
Summary
A series of new poly(arylene ether 1,3,4-oxadiazole)s has been obtained starting from a difluorosubstituted monomer containing
1,3,4-oxadiazole rings and some dihydroxynaphthalene isomers. The polymers have been prepared by polycondensation in solution
and have been obtained in quantitative yield. They had inherent viscosity from 0.2 to 0.82 dL/g, showed good thermal stability
(10% weight loss temperatures in nitrogen and air were above 460 and 450°C, respectively) and high glass transition temperatures
(in the range of 197–232°C). The polymers were characterized by elemental and infrared analyses, GPC and wide angle X-ray
diffraction.
Received: 27 June 2000/Revised version: 2 October 2000/Accepted: 2 October 2000 相似文献
80.
Anna Di Gianni Giovanna Colucci Aldo Priola Lucia Conzatti Matteo Alessi Paola Stagnaro 《大分子材料与工程》2009,294(10):705-710
The preparation of new rubber based nanocomposites by using properly modified organophilic clays is described. A commercial organophilic montmorillonite containing a hydroxylated ammonium ion is reacted with LPBs. The reaction causes a decrease of the polarity of the clay and a great increase of the interlayer distance. The modified organoclays are successfully dispersed into rubber matrices (SBR or BR) by melt blending in an internal batch mixer. SAXS analyses and TEM micrographs revealed the formation of highly exfoliated nanocomposites containing intercalated stacks made of few lamellae.