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Biblioteca Digital do IPB (53.442 recursos)

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DTQB - Comunicações em Conferências Nacionais

Mostrando recursos 1 - 20 de 81

  1. Separation of human immunoglobulin G subclasses using monolithic column

    Leblebici, P.; Rodrigues, A.E.; Pais, L.S.
    The present study aims to separate hIgG into its subclasses using monolithic stationary phase.

  2. Influence of solvent composition on chiral separation of flurbiprofen and ketoprofen enantiomers using simulated moving bed chromatography

    Ribeiro, António E.; Gomes, P. Sá; Pais, L.S.; Rodrigues, A.E.
    Nowadays, simulated moving bed (SMB) chromatography is a well-established technique for chiral separation, as confirmed by the actual large number of published works in chemical and pharmaceutical research. Although there is a considerable number of published works on SMB technology, there are still few concerning the influence of mobile phase composition in SMB operation. This is a new topic on SMB research with very few published works, particularly those presenting not only simulation results predicted from analytical data, but also experimental results at a preparative and SMB scales. The recent outcomes of the authors are directed to the selection of the...

  3. Removal of Cd2+ and Cu2+ by free and immobilized saccharomyces cerevisiae: kinetic and equilibrium modeling

    Martins, Ramiro; Vilar, Vitor; Boaventura, Rui
    Removal of Cd2+ and Cu2+ by free and immobilized Saccharomyces cerevisiae: kinetic and equilibrium modeling.

  4. Separation of human immunoglobulin G subclasses using monolith technology

    Pelin, Arslan; Rodrigues, A.E.; Pais, L.S.
    In this report the synthesis of polymers that can be used for construction of biofunctional bio-degradable supraporous monoliths is described. Such monoliths are suggested as scaffolds for bone tissue engineering. It is well known that major drawbacks of known biodegradable scaffolds based on polylactic acid (PLA) are uncontrollable mechanical properties, as well as obstacle introduction of reactive groups for biofunctionalization.

  5. Micro-flow visualization of in vitro blood through a microchannel with a bifurcation and confluence

    Cidre, Diana; Lima, R.; Fernandes, Carla S.; Dias, Ricardo P.; Ishikawa, Takuji; Imai, Yohsuke; Yamaguchi, Takami

  6. In vitro blood flow in circular PDMS microchannels: effect of the flow rate and hematocrit

    Garcia, Valdemar; Dias, Ricardo P.; Correia, Teresa Montenegro; Pinheiro, Elisa; Pinho, Diana; Lima, R.; Rodrigues, Pedro

  7. Flow of physiological fluids in microchannels: the sedimentation effect

    Garcia, Valdemar; Correia, Teresa Montenegro; Dias, Ricardo P.; Lima, R.

  8. Influence of mobile phase composition on the preparative separation of profens by chiral liquid chromatography

    Ribeiro, António E.; Pais, L.S.; Rodrigues, A.E.
    The chirality of drugs is an important issue for the pharmaceutical industry, since the different enantiomers of a racemic drug may have distinct pharmacological activities, pharmacokinetic and pharmacodynamic effects. Because of its chiral selectivity, human body reacts with a racemic drug differently, and metabolise each enantiomer on separate pathways producing different pharmacological activity. Thus, one isomer may produce the desired therapeutic activities, while the other may be inactive or even, in worst cases, produce unwanted effects.

  9. Release studies of essential oil of Thymus vulgaris L. from PLA microcapsules.

    Martins, I.M.; Rodrigues, S.N.; Barreiro, M.F.; Rodrigues, A.E.
    The incorporation of essential oils, perfumes, deodorants and other active agents in microcapsules with the purpose of controlled release over a certain period of time is being a topic of considerable research in recent years. The controlled release systems are used to deliver compounds such us drugs, pesticides, fragrances or flavors at prescribed rates, together with improved efficacy, safety and convenience. Nowadays, core-shell microcapsules have been investigated extensively for utilization in controlled release systems, especially in drug delivery, where the polymeric wall is a permeable element with porosity that can determine the release behavior of core materials. The aim of...

  10. From oxypropylated olive stone towards novel polymeric materials

    Matos, M.C.; Barreiro, M.F.; Gandini, A.
    The oxypropylation of OH-bearing substrates constitutes an original approach to the rational exploitation of the biomass. Total oxypropylation of a variety of natural polymers, including chitosan and chitin residues, different types of lignins, cork and more complex structures like sugar beet pulp, converts these solids, often otherwise intractable biomass residues, into liquid polyols thanks to the introduction of oligo(propylene oxide) grafts. The transformation of these polyols into rigid polyurethane (RPU) foams has been to date the main studied application. Following our previous work dealing with the optimization of the OS oxypropylation process, the purpose of this work is to explore...

  11. Fungal degradation of lignin-based rigid polyurethane foams

    Sepúlveda, M.; Fernandes, I.P.; Amaral, J.S.; Barreiro, M.F.
    The environmental impacts arising from the use of polymeric materials is a serious problem since they can present long periods of degradation and hence being accumulated in the environment. Polyurethanes (PU) are considered as one of the most versatile polymeric materials offering a wide range of products with applications in diverse sectors. Rigid polyurethane (RPU) foams, due to its excellent insulation and mechanical properties, are widely used in construction, automotive, freeze industry and nautical applications. In this context, the use of green polyols with value-added properties, such as biodegradability, will contribute to reduce environmental impacts. In this work the ability of...

  12. Chitosan-based antimicrobial leather coatings: evaluation of the scale production

    Fernandes, I.P.; Barreiro, M.F.; Pinto, V.; Ferreira, M.J.; Amaral, J.S.
    Chitosan is a biopolymer that is being increasingly used in distinct areas such as pharmaceutical, biomedical, cosmetics, food industry and agriculture. Among the interesting biological activities that have been ascribed to chitosan, the antimicrobial activity is probably the one that generates the higher number of applications. Considering that feet present favorable conditions for microorganism’s growth due to the high relative humidity conditions, warmth and nutrients availability (from feet sweat), one of such applications can be the use of chitosan to provide an antimicrobial coating for leather footwear components. Previous studies, in which leather impregnation with chitosan was performed at laboratory...

  13. The oxypropylation of olive stone and the use of the ensuing polyols for the synthesis of novel polyesters and polyurethanes based on renewable resources

    Matos, M.C.; Barreiro, M.F.; Gandini, A.
    The development of polyols by the oxypropylation of abundant and renewable vegetable and animal resources constitutes an original approach to the exploitation of the biomass. Cellulose, starch, chitosan, chitin, different types of lignins, cork and more complex structures like sugar beet pulp, are among the documented examples. All these systems displayed a similar pattern in terms of the grafting of short poly(propylene oxide) (POP) chains from the OH groups of the substrate, albeit of course each situation required a specific set of optimized experimental conditions to transform the natural solid into a viscous polyol. The transformation of these polyols into...

  14. Solvent-free aqueous polyurethane dispersions

    Fernandes, I.P.; Barreiro, M.F.; Costa, M.R.N.
    The industrial production of aqueous polyurethane dispersions (PUDs) is nowadays a well established technology. There are two main synthetic routes to produce PUDs: the acetone process (a former process developed by Bayer AG) and the pre-polymer process (developed as an alternative response to the patented acetone process). Comparatively to the acetone process, the pre-polymer process has one major advantage since it requires none or only small amounts of acetone. The pre-polymer process, at present, is being forced to readapt due to ongoing developments, partly motivated by process constraints, raw materials restrictions and the need to obtain a true solvent-free product. Allied to this fact it is worth mentioning the European REACH legislation, which is...

  15. FTIR and NMR studies on lignin acetylation

    Cateto, C.A.; Barreiro, M.F.; Rodrigues, A.E.; Brochier-Salon, M.C.; Thielemans, W.; Belgacem, M.N.
    In this work, a comparative study of an acetylation procedure, using four different lignin samples was performed. The chosen lignin samples, Indulin AT (Meadwestvaco), Alcell (Repap), Curan 27-11P (Borregaard LignoTech) and Sarkanda (Granit SA), represent both the guaiacyl and guaiacyl-syringyl type, and were obtained from different pulp processes (kraft and organosolv). Lignin was acetylated using an acetic anhydride-pyridine mixture and the final sample was recovered by precipitation. Final samples, with different reaction times (1 and 2 hours), were characterized by FTIR and 13C NMR analysis, and the obtained spectra were compared with the corresponding ones for non-acetylated samples. Within the...

  16. Synthesis of polyurethane-urea microcapsules with perfume for textile application

    Rodrigues, S.N.; Martins, I.M.; Fernandes, Isabel; Barreiro, M.F.; Mata, Vera; Rodrigues, A.E.
    Synthesis of polyurethane-urea microcapsules with perfume for textile application. In Particules - Micro-Nano encapsulation. Belrlin, Germany. Resumo: This work is a contribution to the introduction of emergent technologies in the textile sector, namely the microencapsulation of fragrances and its application to obtain added-value products. Polyurethane/urea microcapsules with a perfume have been produced using the interfacial polymerization technology for industrial application on textile substrate having in view man suits production. The specific objective of this work is the production of a scented clothing line, which includes: Development of technologies/processes for the production of microcapsules; Incorporation of microcapsules into textile substrates and...

  17. Lignin-based polyurethane elastomers

    Cateto, C.A.; Barreiro, M.F.; Rodrigues, A.E.; Belgacem, M.N.
    The incorporation of lignin into polymeric materials, directly or after chemical modification, is recognized as one of the most viable approaches to accomplish its valorisation and properly exploit its unique intrinsic properties. In this work polyurethanes with elastomeric properties have been synthesised using a three component system based on lignin, 4,4’-methylene-diphenylene diisocyanate (MDI) and polycaprolactone (PCL). The following variables were studied: the lignin type (Alcell (A) and Indulin AT (IAT)), the PCL molecular weight (400, 750 and 1000) and the lignin content (10, 15, 20 and 25% (w/w)). The results pointed out for effective lignin incorporation into the generated polyurethane...

  18. Microencapsulation by coacervation of biodegradable polymer with thyme oil

    Martins, I.M.; Rodrigues, S.N.; Barreiro, M.F.; Rodrigues, A.E.
    The objective of this work is to develop a novel coacervation process to produce microcapsules of PLA to encapsulate thyme oil that will be used in cosmetics. PLA is soluble in organic solvents but insoluble in water. Generally, PLA is used to encapsulate water soluble active principles such as drugs, pesticides and dye-stuffs by coacervation, mainly by means of microspheres production or by using double emulsion techniques (o/w/o). However, the objective of this work is to encapsulate thyme oil, a water insoluble active principle that needs, in a first step, the preparation of an oil-in-water emulsion. The novelty of our...

  19. Rigid composite materials from olive brush seed and unsaturated polyester resin

    Jiménez, L.; Sibaja, M.; Alvarado, P.; Jimenez, G.; Barreiro, M.F.; Cateto, C.A.; Lopretti, M.
    A composite material using unsaturated commercial polyester resin (UPE) and olive brush seed (OBS) was prepared. OBS was treated with sodium hydroxide and maleic anhydride (MAN) and subsequently utilized in a proportion of 35 wt.% to prepare a composite material. These materials were evaluated in terms of moisture absorption, surface density, and mechanical properties such as flexure and tensile tests.

  20. Size exclusion chromatography of lignin in N-N-dimethylformamide/lithium bromide

    Cateto, C.A.; Barreiro, M.F.; Belgacem, M.N.; Rodrigues, A.E.
    The understanding of the macromolecular properties of lignin requires information on its molecular weight distributions. Size exclusion chromatography using DMF/LiBr as the mobile phase and PS-DVB gels as the stationary phase is a widely used system. In this study, two different lignin samples, Indulin-AT and Alcell, were analysed under different experimental conditions. The effect of temperature (60 and 80 ºC), LiBr concentration (0.1 and 0.9%, w/w) and sample preparation conditions (lignin concentration and dissolution time prior to analysis) were analysed. The influence of temperature and ionic strength on a polystyrene-based calibration curve was also studied. The two lignin samples have...

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