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91.
Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. 相似文献
92.
93.
Paulo Ronaldo Sousa Teixeira Ana Siqueira do Nascimento Marreiro Teixeira Emanuel Airton de Oliveira Farias Durcilene Alves da Silva Lívio César Cunha Nunes Cleide Maria da Silva Leite Edson Cavalcanti da Silva Filho Carla Eiras 《Journal of Polymer Research》2018,25(5):127
The babassu coconut is a plant very abundant in northeast of Brazil and other countries, and any part of plant and fruit becomes residue. In this study, babassu mesocarp (Orbignya sp) (BM) was chemically modified with phthalic anhydride (BMPA) to increase its solubility in an aqueous medium, and thus facilitate its processing in the form of thin films. The reaction of modification of the babassu mesocarp with phthalic anhydride (PA), obtaining BMPA, was confirmed by FTIR, XRD, TG/DTG, Zeta Potential and SEM analysis, from the differences in the bands of the FTIR spectra, increase in crystallinity, new thermal profile, changes in zeta potential value and morphology, respectively. The thin monolayer films of BM and BMPA were produced by the self-assembly monolayer (SAM) technique, and adsorbed onto conductive glass substrates (tin-doped indium oxide, ITO). The electroactive properties of these thin films were evaluated by cyclic voltammetry (CV). BM exhibited a pair redox pair process of +0.57 V(oxidation) and?+?0.19 V (reduction) for BM. In BMPA these redox processes were observed at +0.37 V (oxidation) and 0.24 V vs. ECS (reduction), verifying that both BM and BMPA are electroactive materials that can be used in the construction of sensor platforms, without the necessity of being conjugated with other electroactive materials, such as conductive polymers, metal phthalocyanines, or dyes. Furthermore, under the experimental conditions used, the BMPA presented a more reversible redox process and higher electrochemical stability in comparison to BM. This effect occurs because BMPA has higher solubility in aqueous media, which favors the preparation of films with smaller grain sizes compared to BM films, as observed by Atomic Force Microscopy (AFM). This study showed that BMPA is a new material with potential for applications in electrochemical sensors. 相似文献
94.
Measurements of horizontal three‐phase solid‐liquid‐gas slug flow: Influence of hydrate‐like particles on hydrodynamics 下载免费PDF全文
Luis M. M. Rosas Carlos L. Bassani Rafael F. Alves Fábio A. Schneider Moisés A. Marcelino Neto Rigoberto E. M. Morales Amadeu K. Sum 《American Institute of Chemical Engineers》2018,64(7):2864-2880
Gas hydrate formation is a main flow assurance concern in oil and gas production. Understanding the effects of the introduction of solid particles in the slug flow is essential to improve the efficiency and safety of multiphase production. The purpose of the present work is the experimental characterization of solid‐liquid‐gas slug flow with the presence of dispersed hydrate‐like particles. Experimental tests were carried out with inert polyethylene particles of 0.5‐mm diameter with density similar to gas hydrates (938 kg/m3). The test section comprised a 26‐mm ID, 9‐m length horizontal duct of transparent Plexiglas. High Speed Imaging and resistivity sensors was used to analyze the slug flow unit cell behavior due to the introduction of the solid particles and to measure the unit cell translational velocity, the slug flow frequency, the bubble and slug lengths, and the phase fractions. Two distinct concentrations of solid particles were tested (6 and 8 g/dm3). © 2018 American Institute of Chemical Engineers AIChE J, 64: 2864–2880, 2018 相似文献
95.
Synthesis and Characterization of Novel Surfactants Based on 2-Hydroxy-4-(methylthio)butanoic Acid: 2. Non-ionic Surfactants 下载免费PDF全文
96.
Improvement of glycerin removal from crude biodiesel through the application of a sulfonated polymeric adsorbent material 下载免费PDF全文
Magno José Alves Saulo Luiz Cardoso Eloiza Guimarães Waldomiro Borges Neto Vicelma Luiz Cardoso Miria Hespanhol Miranda Reis 《应用聚合物科学杂志》2017,134(38)
The proposal of suitable processes for glycerin removal from crude biodiesel is an important task for making the overall biodiesel production process environmentally friendly and economically viable. In this article, we propose a dry purification process for biodiesel treatment with different polymeric materials [chitosan, cellulose acetate, poly(vinyl alcohol) (PVA), and sulfonated PVA]. Except for pure PVA, all of the proposed materials were able to reduce the free glycerin content of crude biodiesel from 0.03 wt % to values lower than 0.02 wt %. When the PVA was sulfonated, the glycerin removal increased from 12 to 82% compared that of pure PVA. The glycerin content in the biodiesel sample treated with sulfonated PVA was 0.0055 wt %. Mid‐IR spectrometric analysis showed that the sulfonation of PVA increased the band due to H? O? H stretching vibrations; this enabled greater hydrogen bonding between glycerol and the ? SO3? groups of the sulfonated adsorbent. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45330. 相似文献
97.
Alves CR Murai IH Ramona P Nicastro H Bechara LR Lancha AH Brum PC Irigoyen MC Gualano B 《Journal of the International Society of Sports Nutrition》2012,9(1):13-4
Background
Exacerbated oxidative stress is thought to be a mediator of arterial hypertension. It has been postulated that creatine (Cr) could act as an antioxidant agent preventing increased oxidative stress. The aim of this study was to investigate the effects of nine weeks of Cr or placebo supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats (SHR).Findings
Lipid hydroperoxidation, one important oxidative stress marker, remained unchanged in the coronary artery (Cr: 12.6 ± 1.5 vs. Pl: 12.2 ± 1.7 nmol·mg-1; p = 0.87), heart (Cr: 11.5 ± 1.8 vs. Pl: 14.6 ± 1.1 nmol·mg-1; p = 0.15), plasma (Cr: 67.7 ± 9.1 vs. Pl: 56.0 ± 3.2 nmol·mg-1; p = 0.19), plantaris (Cr: 10.0 ± 0.8 vs. Pl: 9.0 ± 0.8 nmol·mg-1; p = 0.40), and EDL muscle (Cr: 14.9 ± 1.4 vs. Pl: 17.2 ± 1.5 nmol·mg-1; p = 0.30). Additionally, Cr supplementation affected neither arterial blood pressure nor heart structure in SHR (p > 0.05).Conclusions
Using a well-known experimental model of systemic arterial hypertension, this study did not confirm the possible therapeutic effects of Cr supplementation on oxidative stress and cardiovascular dysfunction associated with arterial hypertension. 相似文献98.
L. Šiller L. Alves A. C. Brieva Yu. V. Butenko M. R. C. Hunt 《Topics in Catalysis》2009,52(11):1604-1610
We review the currently known methods of producing gold nitride and report on the influence of electrically isolated substrates
on the growth of gold nitride films by reactive ion sputtering (RIS). It is found that isolation of the substrate decreases
grain size and increases nitrogen content, the latter attributed to longer nitrogen ion lifetime on the surface of the growing
film. The chemical reactivity of gold nitride is compared with that of pure gold films using the adsorption of 1-dodecyl mercaptan
(CH3(CH2)11SH) as a model system and it is found that there is no significant difference between gold films and gold nitride in terms
of Au–S binding. However, gold nitride nanoparticles are suggested to be worthy of further investigation in terms of their
catalytic properties.
相似文献
L. ŠillerEmail: |
99.
M.L. Afonso A. Gomes A. Carvalho L.C. Alves F. Wastin A.P. Gonalves 《Electrochimica acta》2009,54(28):7318-7323
The electrochemical behaviour of UCl4 (0.01 mol L−1 up to 0.05 mol L−1) in 0.1 mol L−1 TBAPF6/DMF solution at vitreous carbon was studied, at room temperature, by cyclic voltammetry and potentiostatic techniques. The electrolytic solutions were analyzed by UV spectroscopy (UV), and the electrodeposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction (XRD). The cyclic voltammetric results, at low UCl4 concentrations (0.01 mol L−1), point that the reduction of U(IV) to U(0) occurs in two steps involving mainly U(IV) and U(III) species. The first electron transfer reaction is quasi-reversible and the second irreversible. The diffusion coefficient of U(IV) in DMF and the charge rate constant were determined to be 4.78 × 10−7 cm2 s−1 and 1.93 × 10−3 cm s−1 (at 0.02 V s−1), respectively.RBS data obtained from samples prepared at constant potential (−3.10 V) during 3 h at room temperature, indicated the presence of uranium particles deposited all over the vitreous carbon surface with aggregates in some places, confirming that the second reduction step corresponds to uranium electrodeposition. No crystallographic ordering could be seen by XRD, pointing to an amorphous character of the uranium films. 相似文献
100.
Michele Espinosa da Cunha Laiza Canielas Krause Maria Silvana Aranda Moraes Candice Schmitt Faccini Rosângela Assis Jacques Suelen Rodrigues Almeida Maria Regina Alves Rodrigues Elina Bastos Caramão 《Fuel Processing Technology》2009
In the present work, the process of biodiesel production in a pilot plant has been studied using beef tallow as raw materials with methanol and potassium hydroxide as catalyst. The biodiesel quality is regulated by Brazilian specifications (Resolution 42) by the National Agency of Petroleum (ANP). The alkaline transesterification of animal fat with methanol produces a biodiesel with high quality and also with a good conversion rate. The process is possible but the economical viability must be improved by recovering methanol and glycerin. The obtained results have been used for industrial scale up of the process. 相似文献