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1.
J Colloid Interface Sci ; 677(Pt B): 719-728, 2025 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-39167963

RESUMO

Hard carbons derived from pitch are considered a competitive low-cost anode for sodium-ion batteries. However, the preparation of pitch-based hard carbon (PHC) requires the aid of a pre-oxidation strategy, which introduces unnecessary defects and oxygen elements, which leads to low initial Coulombic efficiency (ICE) and poor cycling stability. Herein, we demonstrate a new surface engineering strategy by grafting chemically active glucose molecules on the PHC surface via esterification reactions, which can achieve low-cost nano-scaled carbon coating. Thin glucose coating can be carbonized at a lower temperature, which results in a more closed pore structure and fewer functional groups. The as prepared PHC exhibits a high reversible capacity of 328.5 mAh/g with a high ICE of 92.08 % at 0.02 A/g. It is noteworthy that the PHC can be adapted to a variety of cathode materials for full-cell assembling without pre-sodiation, which maintains the characteristics of high capacity and excellent cycling stability. The performance of resin-based hard carbon coated with a similar method was also improved, demonstrating the universality of the technique.

2.
J Agric Food Chem ; 71(24): 9201-9212, 2023 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-37289784

RESUMO

This review addresses the possibilities of using supercritical carbon dioxide (SC-CO2) in the flavor industry in extraction and fractionation processes and its use as a reaction medium to generate aroma esters. The advantages and disadvantages are presented, comparing SC-CO2 processing with traditional methods. The most distinguishable features of SC-CO2 include mild reaction conditions, time savings, fewer toxicity concerns, higher sustainability, and the possibility of modulating solvent selectivity according to the process conditions (such as pressure and temperature). Thus, this review indicates the potential of using SC-CO2 to obtain a high selectivity of compounds that can be applied in aroma technology and related fields.


Assuntos
Dióxido de Carbono , Cromatografia com Fluido Supercrítico , Odorantes , Solventes , Tecnologia , Fracionamento Químico , Cromatografia com Fluido Supercrítico/métodos
3.
Int J Mol Sci ; 20(24)2019 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-31835372

RESUMO

In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.


Assuntos
Materiais Biocompatíveis , Dendrímeros , Portadores de Fármacos , Glicerol , Poliésteres , Polímeros , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/uso terapêutico , Dendrímeros/síntese química , Dendrímeros/química , Dendrímeros/uso terapêutico , Portadores de Fármacos/síntese química , Portadores de Fármacos/química , Portadores de Fármacos/uso terapêutico , Glicerol/síntese química , Glicerol/química , Glicerol/uso terapêutico , Humanos , Poliésteres/síntese química , Poliésteres/química , Poliésteres/uso terapêutico , Polímeros/síntese química , Polímeros/química , Polímeros/uso terapêutico , Medicina Regenerativa
4.
Crit Rev Biotechnol ; 39(7): 884-903, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31382780

RESUMO

Since several decades ago, the application of pervaporation (PV) technology has been mainly aimed at the separation of different types of water-organic, organic-water and organic-organic mixtures, reaching its large-scale application in industry for the dehydration of organics. Today, the versatility and high selectivity toward specific compounds have led its consideration to other types of application such as the assisted chemical and bio-chemical reactions. The focus of this review is to provide a compelling overview on the recent developments of PV combined with chemical and bio-chemical reactions. After a general introduction of PV and its theoretical background, particular emphasis is given to the results obtained in the field for different reactions considered, identifying the key features and weak points of PV in such particular applications. Furthermore, future trends and perspectives are also addressed according to the latest literature reports.


Assuntos
Biotecnologia/métodos , Membranas Artificiais , Biotecnologia/instrumentação , Compostos Orgânicos/química , Polímeros/química , Volatilização , Água/química
5.
Polymers (Basel) ; 10(8)2018 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-30960758

RESUMO

The reaction of citric acid with wood veneers was studied by Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (CP MAS 13C NMR) and matrix assisted laser desorption ionization time of flight (MALDI ToF) mass spectrometry. The analysis showed that reactions of citric acid occurred with both lignin and carbohydrate constituents of wood. The reactions occurring are esterifications between the carboxylic acid functions of citric acid and the numerous aromatic and aliphatic hydroxyl groups of the main wood constituents. Reaction of citric acid with glucose as a simple model compound of carbohydrates hydroxyl groups also yielded reactions leading to linear and branched oligomers by esterification. The result indicate that the reactions of esterification are accompanied in parallel by some internal rearrangements of lignin. The applied results on bonding wide flat wood surfaces such as veneers to obtain LVL panels yielded excellent strength results even if the conditions of pressing were more drastic than what is usual for this application. The applied bonding results have shown that citric acid has great potential to be used as a bio-binder for wood veneers.

6.
J Chromatogr A ; 1456: 235-41, 2016 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-27320376

RESUMO

In order to analyze the composition of fatty acids employing gas chromatography as the separation method, a derivatization of lipids using esterification and transesterification reactions is needed. The methodologies currently available are time consuming and use large amounts of sample and reagents. Thus, this work proposes a new procedure to carry out the derivatization of fatty acids without the need for prior extraction of lipids. The use of small amounts of sample (100mg) allows the analysis to be performed in specific parts of animals, in most cases without having them slaughtered. Another benefit is the use of small amounts of reagents (only 2mL of NaOH/Methanol and H2SO4/Methanol). The use of an experimental design procedure (Design Expert software) allows the optimization of the alkaline and acid reaction times. The procedure was validated for five minutes in both steps. The method was validated for bovine fat, beef, chicken, pork, fish and shrimp meats. The results for the merit figures of accuracy (from 101.07% to 109.18%), precision (RSDintra-day (from 0.65 to 3.93%), RSDinter-day (from 1.57 to 5.22%)), linearity (R(2)=0.9864) and robustness confirmed that the new method is satisfactory within the linear range of 2-30% of lipids in the sample. Besides the benefits of minimizing the amount of samples and reagents, the procedure enables gas chromatography sample preparation in a very short time compared with traditional procedures.


Assuntos
Cromatografia Gasosa , Ácidos Graxos/análise , Ácidos Graxos/química , Carne/análise , Animais , Bovinos , Galinhas , Peixes , Indicadores e Reagentes , Lipídeos/química , Produtos Avícolas/análise , Carne Vermelha , Reprodutibilidade dos Testes , Alimentos Marinhos/análise , Suínos , Ultrassom
7.
Ultrason Sonochem ; 22: 89-94, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24844439

RESUMO

In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7M) were tested using ultrasound as an alternative to mechanical agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where mechanical agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30°C, reaching 61% of conversion in 6h. Molecular sieves (3Å) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6h, when 60mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using mechanical agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.


Assuntos
Ascomicetos/enzimologia , Biocatálise , Butiratos/síntese química , Técnicas de Química Sintética/métodos , Enzimas Imobilizadas/metabolismo , Lipase/metabolismo , Ultrassom , Butiratos/química , Enzimas Imobilizadas/química , Esterificação , Resinas de Troca Iônica/química , Lipase/química , Temperatura
8.
Mater Sci Eng C Mater Biol Appl ; 39: 35-9, 2014 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-24863194

RESUMO

Starch/PBAT blends were produced by reactive extrusion with tartaric acid (TA) as an additive. The effects of TA, glycerol and starch+PBAT on the mechanical, optical and structural properties of the films were evaluated, with formulations based in a constrained mixture design. Tartaric acid acts as a compatibiliser and promotes the acid hydrolysis of starch chains. These two functions explain the observed film resistance and opacity. TA reduced the weight loss in water. Scanning electron microscopy (SEM) images showed that TA reduces the interfacial tension between the polymeric phases, resulting in more homogeneous films. Nuclear magnetic resonance ((13)C CPMAS) and Fourier transform infrared spectroscopy (FT-IR) suggest that tartaric acid is able to react with the hydroxyl groups of the starch by esterification/transesterification reactions, confirming its role as a compatibiliser. The addition of TA results in materials with better properties that are suitable for use in food packaging.


Assuntos
Poliésteres/química , Amido/química , Tartaratos/química , Esterificação , Glicerol/química , Espectroscopia de Ressonância Magnética , Manihot/química , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
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