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2018
dos Santos, LM, Ligabue R, Dumas A, Le Roux C, Micoud P, Meunier J-F, Martin F, Corvo M, Almeida P, Einloft S.  2018.  Waterborne polyurethane/Fe3O4-synthetic talc composites: synthesis, characterization, and magnetic properties. Polymer Bulletin. :1–16.: Springer Berlin Heidelberg AbstractWebsite

Nano-Fe3O4-synthetic talc gel was used as filler in the synthesis of waterborne polyurethane/Fe3O4-synthetic talc nanocomposites. This filler presents numerous edges (Si–O and Mg–O) and OH groups easily forming hydrogen bonds and polar interaction with water conferring hydrophilic character, consequently improving filler dispersion within a water-based matrix. Yet, the use of waterborne polyurethane (WPU) as matrix must be highlighted due to its environmentally friendly characteristics and low toxicity compared to solvent-based product. Fe3O4-synthetic talc-nanofillers were well dispersed into the polyurethane matrix even at high filler content as supported by XRD and TEM analyses. NMR indicates the interaction of filler OH groups with the matrix. For all nanocomposites, one can see a typical ferromagnetic behavior below Curie temperature (about 120 K) and a superparamagnetic behavior above this temperature. The use of Fe3O4-synthetic talc for obtaining magnetic nanocomposites resulted in improved materials with superior mechanical properties compared to solvent-based nanocomposites.

Surra, E, Bernardo M, Lapa N, Esteves I, Fonseca I, Mota JP.  2018.  Maize cob waste pre-treatments to enhance biogas production through co-anaerobic digestion with OFMSW. Waste Management. 72:193-205. AbstractWebsite

In the present work, the enhancement of biogas and methane yields through anaerobic co-digestion of the pre-hydrolised Organic Fraction of Municipal Solid Wastes (hOFMSW) and Maize Cob Wastes (MCW) in a lab-scale thermophilic anaerobic reactor was tested. In order to increase its biodegradability, MCW were submitted to an initial pre-treatment screening phase as follows: (i) microwave (MW) irradiation catalysed by NaOH, (ii) MW catalysed by glycerol in water and alkaline water solutions, (iii) MW catalysed by H2O2 with pH of 9.8 and (iv) chemical pre-treatment at room temperature catalysed by H2O2 with 4 h reaction time. The pre-treatments cataysed by H2O2 were performed with 2% MCW (wMCW/v alkaline water) at ratios of 0.125, 0.25, 0.5 and 1.0 (wH2O2/wMCW). The pre-treatment that presented the most favourable balance between sugars, lignin, cellulose and hemicellulose solubilisations, as well as low production of phenolic compound and furfural (inhibitors), was the chemical pre-treatment catalysed by H2O2, at room temperature, with a ratio of 0.5 wH2O2/wMCW (Pre1). This Pre1 was then optimised testing reaction times of 1, 2 and 3 days at a different pH (11.5) and MCW percentage (10% w/v). The optimised pre-treatment that presented the best results, considering the same criteria defined above, was the one carried out during 3 days, at pH 9.8 and 10% MCW w/v (Pre2). The anaerobic reactor was initially fed with the hOFMSW obtained from the hydrolysis tank of an industrial AD plant. The hOFMSW was than co-digested with MCW submitted to the pre-treatment Pre1. In another assay, hOFMSW was co-digested with MCW submitted pre-treatment Pre 2. The co-digestion of hOFMSW + Pre1 increased the biogas yield by 38.9% and methane yield by 29.7%, when compared to the results obtained with hOFMSW alone. The co-digestion of hOFMSW + Pre2 increased biogas yield by 46.0% and CH4 yield by 36.3%. In both cases, the methane content obtained in the biogas streams was above 66% v/v. These results show that pre-treatment with H2O2, at room temperature, is a promising low cost way to valorize MCW through co-digestion with hOFMSW.

2017
Sulim, O, Ribeiro R, Esteves I, Antunes C, Garate A, Duarte P, Ferreira I, Mota J, Plaza M.  2017.  Design of structured adsorbents for aplications in gas adsorption processes - Conventional shaping vs 3D-Printed formulation, 5-10 March. Abstract

Microporous materials highly activated and with potential to be used as adsorbents in many applications for gas
separation/purification are usually available as powders. These solids usually have a great and reversible gas
uptake, high gas selectivity, good chemical and thermal stability, but are unsuitable to be used in gas adsorption
processes, such as Pressure Swing Adsorption (PSA) or Simulated Moving Bed (SMB).
Zeolites, carbons and more recently metal-organic frameworks (MOFs) are examples of those materials. Their
use in adsorption-based processes are dependent of their upgrading from powders (micrometer scale) to
particles (pellets, spheres or granules at millimeter scale). This would overcome large pressure drops and
consequent energy consumptions when packing adsorbent columns in those processes. Thus, shaping
adsorbents is an important step to use them in industry, although it greatly affects their capacity and selectivity
towards a specific gas separation.
In this work, we explore techniques to shape powdered adsorbents, followed by their textural and mechanical
characterizations, and the study of their adsorption properties towards the main components of post-combustion
flues gases (CO2 and N2). Materials densification is proposed by employing two approaches:
- Conventional shaping through binderless mechanical compression and binder-containing extrusion; and
- Formulation by 3D printing (or additive manufacturing) to produce packed bed morphologies that
precisely replicate computer aided design (CAD) models.
Porous separation media are important for fluid-solid contacting in many unit operations, including adsorption.
Due to practical limitations, media particles are typically packed randomly into a column in a shaped form,
allowing fluid to flow through the interstitial voids. Key to the effectiveness of packed columns are the flowrelated properties of mass transfer, fluid distribution and dispersion, and back pressure, which in turn depend
upon packing geometry. Until now, no alternative was found to overcome this limitation and have optimal
ordered packing arrangements at the micron scale. 3D-Printing (or additive manufacturing) brings a wide range
of benefits that traditional methods of manufacturing or prototyping simply cannot. With this approach, complex
ordered geometries, that are not possible by conventional extrusion, can be designed and printed for a porous
media, being the equipment resolution the only limiting step to overcome.
The effect of parameters like compression force, particle sieving, binder nature, binder/adsorbent ratio were
firstly studied using conventional shaping techniques, as a basis for the consequent development of 3D-printed
formulations. The structured samples are then characterized and adsorption equilibria studies are performed on
them to evaluate their performance as media for gas adsorption separation processes. A volumetric/manometric
adsorption unit built in-house was used for this purpose. Relevant experimental data is obtained, which allows to
conclude that 3D-printed media can be an alternative porous media for application in gas adsorption processes.

Huang, RJ, Avo J, Northey T, Chaning-Pearce E, dos Santos PL, Ward JS, Data P, Etherington MK, Fox MA, Penfold TJ, Berberan-Santos MN, Lima JC, Bryce MR, Dias FB.  2017.  The contributions of molecular vibrations and higher triplet levels to the intersystem crossing mechanism in metal-free organic emitters, 2017. Journal of Materials Chemistry C. 5(25):6269-6280. AbstractWebsite
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Czerwinska, K, Machura B, Kula S, Krompiec S, Erfurt K, Roma-Rodrigues C, Fernandes AR, Shul'pina LS, Ikonnikov NS, Shul'pin GB.  2017.  Copper(ii) complexes of functionalized 2,2[prime or minute]:6[prime or minute],2[prime or minute][prime or minute]-terpyridines and 2,6-di(thiazol-2-yl)pyridine: structure, spectroscopy, cytotoxicity and catalytic activity, 2017. Dalton Transactions. 46(29):9591-9604.: The Royal Society of Chemistry AbstractWebsite

Six new copper(ii) complexes with 2,2[prime or minute]:6[prime or minute],2[prime or minute][prime or minute]-terpyridine (4[prime or minute]-Rn-terpy) [1 (R1 = furan-2-yl), 2 (R2 = thiophen-2-yl), and 3 (R3 = 1-methyl-1H-pyrrol-2-yl)] and 2,6-di(thiazol-2-yl)pyridine derivatives (Rn-dtpy) [4 (R1), 5 (R2), and 6 (R3)] have been synthesized by a reaction between copper(ii) chloride and the corresponding ligand. The complexes have been characterized by UV-vis and IR spectroscopy, and their structures have been determined by X-ray analysis. The antiproliferative potential of copper(ii) complexes of 2,2[prime or minute]:6[prime or minute],2[prime or minute][prime or minute]-terpyridine and 2,6-di(thiazol-2-yl)pyridine derivatives towards human colorectal (HCT116) and ovarian (A2780) carcinoma as well as towards lung (A549) and breast adenocarcinoma (MCF7) cell lines was examined. Complex 1 and complex 6 were found to have the highest antiproliferative effect on A2780 ovarian carcinoma cells, particularly when compared with complex 2, 3 with no antiproliferative effect. The order of cytotoxicity in this cell line is 6 > 1 > 5 > 4 > 2 [approximate] 3. Complex 2 seems to be much more specific towards colorectal carcinoma HCT116 and lung adenocarcinoma A549 cells. The viability loss induced by the complexes agrees with Hoechst 33258 staining and typical morphological apoptotic characteristics like chromatin condensation and nuclear fragmentation. The specificity towards different types of cell lines and the low cytotoxic activity towards healthy cells are of particular interest and are a positive feature for further developments. Complexes 1-6 were also tested in the oxidation of alkanes and alcohols with hydrogen peroxide and tert-butyl-hydroperoxide (TBHP). The most active catalyst 4 gave, after 120 min, 0.105 M of cyclohexanol + cyclohexanone after reduction with PPh3. This concentration corresponds to a yield of 23% and TON = 210. Oxidation of cis-1,2-dimethylcyclohexane with m-CPBA catalyzed by 4 in the presence of HNO3 gave a product of a stereoselective reaction (trans/cis = 0.47). Oxidation of secondary alcohols afforded the target ketones in yields up to 98% and TON = 630.

João, C, Echeverria C, Velhinho A, Silva JC, Godinho MH, Borges JP.  2017.  Bio-inspired production of chitosan/chitin films from liquid crystalline suspensions. Carbohydrate polymers. 155:372-381. AbstractWebsite

Inspired by chitin based hierarchical structures observed in arthropods exoskeleton, this work reports the capturing of chitin nanowhiskers’ chiral nematic order into a chitosan matrix. For this purpose, highly crystalline chitin nanowhiskers (CTNW) with spindle-like morphology and average aspect ratio of 24.9 were produced by acid hydrolysis of chitin. CTNW were uniformly dispersed at different concentrations in aqueous suspensions. The suspensions liquid crystalline phase domain was determined by rheological measurements and polarized optical microscopy (POM). Chitosan (CS) was added to the CTNW isotropic, biphasic and anisotropic suspensions and the solvent was evaporated to allow films formation. The Films’ morphologies as well as the mechanical properties were explored. A correlation between experimental results and a theoretical model, for layered matrix’ structures with fibers acting as a reinforcement agent, was established. The results evidence the existence of two different layered structures, one formed by chitosan layers induced by the presence of chitin and another formed by chitin nanowhiskers layers. By playing on the ratio chitin/chitosan one layered structure or the other can be obtained allowing the tunning of materials’ mechanical properties.

Soares, PIP, Echeverria C, Baptista AC, João C, Fernandes S, Almeida A, Silva JC, Godinho MH, Borges JP.  2017.  Hybrid polysaccharide-based systems for biomedical applications. Hybrid Polymer Composite Materials: Applications. (Manju Kumari Thakur, Thakur, Vijay Kumar, Asokan Pappu, Eds.).:107-149., USA: Woodhead Publishing, Elsevier Abstract

Hybrid materials have been widely studied for structural applications. Polysaccharide-based fibers, especially cellulosic fibers, have been explored in the last two decades as substitutes of the traditional reinforcements made of glass or carbon fibers due to their mechanical properties. However, their biocompatibility, biodegradability, and chemistry have attracted the researchers and new developments in the field of smart and functional materials arise in diverse applications. This chapter will focus on the biomedical applications of polysaccharide-based smart and functional materials, namely those concerning biosensors and actuators, theranostic systems, and tissue-engineering applications. Special attention will be given to cellulose- and chitin/chitosan-based hybrid materials because these are the two most abundant polysaccharides and probably the most promising for the development of hybrid materials for biomedical applications. Biomimetic strategies for the development of smart and functional hybrid materials will also be highlighted.

Bonnet, A, Grosso AR, Elkaoutari A, Coleno E, Presle A, Sridhara SC, Janbon G, Geli V, de Almeida SF, Palancade B.  2017.  Introns Protect Eukaryotic Genomes from Transcription-Associated Genetic Instability. Molecular Cell. :1–14. AbstractWebsite

Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage.

Dantas, JM, Brausemann A, Einsle O, Salgueiro CA.  2017.  NMR studies of the interaction between inner membrane-associated and periplasmic cytochromes from Geobacter sulfurreducens. FEBS Letters. 591:1657–1666. AbstractWebsite

Geobacter sulfurreducens is a dissimilatory metal reducing bacterium with notable properties and significance in biotechnological applications. Biochemical studies suggest that the inner membrane-associated diheme cytochrome MacA and the periplasmic triheme cytochrome PpcA from G. sulfurreducens can exchange electrons. In this work, NMR chemical shift perturbation measurements were used to map the interface region and to measure the binding affinity between PpcA and MacA. The results show that MacA binds to PpcA in a cleft defined by hemes I and IV, favoring the contact between PpcA heme IV and the MacA high potential heme. The dissociation constant values indicate the formation of a low affinity complex between the proteins, which is consistent with the transient interaction observed in electron transfer complexes.This article is protected by copyright. All rights reserved.

Faria, J, Echeverria C, Borges JP, Godinho MH, Soares PIP.  2017.  Towards the development of multifunctional hybrid fibrillary gels: production and optimization by colloidal electrospinning. RSC Advances. 7(77):48972-48979. AbstractWebsite

The incorporation of thermosensitive microgels that can act as active sites into polymeric fibers through colloidal electrospinning originates multifunctional, highly porous, and biocompatible membranes suitable for biomedical applications. The use of polyvinylpyrrolidone (PVP), a biocompatible, water-soluble polymer as a fiber template, not only allows the use of a simple set-up to produce composite membranes, but also avoids the use of organic solvents to prepare such systems. Further crosslinking with ultraviolet (UV) radiation avoids membrane dissolution in physiological conditions. Highly porous, UV crosslinked composite membranes with monodisperse mean fiber diameters around 530 nm were successfully produced. These composite membranes showed a Young Modulus of 22 MPa, and an ultimate tensile strength of 3 MPa, accessed in the mechanical tests. Furthermore, the same composite membranes were able to swell about 30 times their weight after 1 hour in aqueous medium. In this work composite multifunctional membranes were designed and extensively studied. PVP, a biocompatible water-soluble polymer, was used as a fiber template to incorporate thermoresponsive poly-(N-isopropylacrylamide) (PNIPAAm)-based microgels into the composite membrane using colloidal electrospinning. The design of multifunctional membranes can be further tailored to several biomedical applications such as temperature-controlled drug delivery systems.

Echeverria, C, Almeida PL, Gutierrez OAF, Rey AD, Godinho MH.  2017.  Two negative minima of the first normal stress difference in a cellulose-based cholesteric liquid crystal: Helix uncoiling. Journal of Polymer Science Part B: Polymer Physics. 55(10):821-830. AbstractWebsite

The shear rate dependence of material functions such as shear viscosity (η) and the first normal stress difference (N1) were given and interpreted earlier by Kiss and Porter. Their widely accepted work revealed the possibility of having a negative minimum of N1 for polymeric liquid crystals. In this work, we disclose for the first time the evidence of two negative N1 minima on a sheared cellulosic lyotropic system. The lower shear rate minimum is ascribed to the uncoiling of the cholesteric helix, as theoretically predicted earlier. Our findings contribute also to the understanding of the other minimum already reported in the literature and attributed to the nematic director tumbling mode. Moreover, the elastic change that the LC-HPC sample undergoes during the helix unwinding of the cholesteric structure is also by means of oscillatory measurements. This study is a contribution for the understanding of the structure-properties relationship linked with the complex rheological behavior of chiral nematic cellulose-based systems and may help to improve their further processing.

dos Santos, LM, Ligabue R, Dumas A, Le Roux C, Micoud P, Meunier J-F, Martin F, Corvo M, Almeida P, Einloft S.  2017.  Waterborne polyurethane/Fe3O4-synthetic talc composites: synthesis, characterization, and magnetic properties. Polymer Bulletin. :1-16.: Springer Berlin Heidelberg AbstractWebsite

Nano-Fe3O4-synthetic talc gel was used as filler in the synthesis of waterborne polyurethane/Fe3O4-synthetic talc nanocomposites. This filler presents numerous edges (Si–O and Mg–O) and OH groups easily forming hydrogen bonds and polar interaction with water conferring hydrophilic character, consequently improving filler dispersion within a water-based matrix. Yet, the use of waterborne polyurethane (WPU) as matrix must be highlighted due to its environmentally friendly characteristics and low toxicity compared to solvent-based product. Fe3O4-synthetic talc-nanofillers were well dispersed into the polyurethane matrix even at high filler content as supported by XRD and TEM analyses. NMR indicates the interaction of filler OH groups with the matrix. For all nanocomposites, one can see a typical ferromagnetic behavior below Curie temperature (about 120 K) and a superparamagnetic behavior above this temperature. The use of Fe3O4-synthetic talc for obtaining magnetic nanocomposites resulted in improved materials with superior mechanical properties compared to solvent-based nanocomposites.

Correa, CR, Bernardo M, Ribeiro RPPL, Esteves IAAC, Kruse A.  2017.  Evaluation of hydrothermal carbonization as a preliminary step for the production of functional materials from biogas digestate. Journal of Analytical and Applied Pyrolysis. 124:461-474. AbstractWebsite

Digestate from a biogas plant that uses solely biomass for biogas production was used as precursor material for the production of activated carbon as an alternative to increase its added value. The digestate was converted into hydrochar by hydrothermal carbonization varying the temperature (190–250°C), residence time (3 and 6h), and pH (5 and 7). Temperature followed by residence time had the strongest influence on the chemical composition and thermal stability of the hydrochars. A significant effect of the pH was not observed. The hydrochars were chemically activated to enhance the surface area and use them as activated carbon. As a consequence, the surface areas increased from 8 to 14m2/g (hydrochars) to 930–1351m2/g (activated carbons). Furthermore, large micropore volumes were measured (0.35–0.50cm3/g). The activated carbons were studied as adsorbents in gas phase applications, showing that the product of digestate is a very effective adsorbent for carbon dioxide (CO2). Especially the activated carbon obtained from the hydrochar produced at 250°C for 6h, which adsorbed 8.80mol CO2/kg at 30°C and 14.8bar. Additionally, the activated carbons showed a stronger affinity towards CO2 compared to methane (CH4), which makes this material suitable for the upgrading of raw biogas to biomethane.

Kowacz, M, Marchel M, Juknaité L, Esperança JMSS, Romão MJ, Carvalho AL, Rebelo LPN.  2017.  Infrared light-induced protein crystallization. Structuring of protein interfacial water and periodic self-assembly. Journal of Crystal Growth. 457:362-368. AbstractWebsite

Abstract We show that a physical trigger, a non-ionizing infrared (IR) radiation at wavelengths strongly absorbed by liquid water, can be used to induce and kinetically control protein (periodic) self-assembly in solution. This phenomenon is explained by considering the effect of İR\} light on the structuring of protein interfacial water. Our results indicate that the İR\} radiation can promote enhanced mutual correlations of water molecules in the protein hydration shell. We report on the radiation-induced increase in both the strength and cooperativeness of H-bonds. The presence of a structured dipolar hydration layer can lead to attractive interactions between like-charged biomacromolecules in solution (and crystal nucleation events). Furthermore, our study suggests that enveloping the protein within a layer of structured solvent (an effect enhanced by İR\} light) can prevent the protein non-specific aggregation favoring periodic self-assembly. Recognizing the ability to affect protein-water interactions by means of İR\} radiation may have important implications for biological and bio-inspired systems.

2016
Santos, L, Silveira CM, Elangovan E, Neto JP, Nunes D, Pereira LÍ, Martins R, Viegas J, Moura JJG, Todorovic S, Almeida GM, Fortunato E.  2016.  {Synthesis of WO3 nanoparticles for biosensing applications}, feb. Sensors and Actuators B: Chemical. 223:186–194. AbstractWebsite
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Marques, S, Soares PIP, Echeverria C, Godinho MH, Borges JP.  2016.  Confinement of thermoresponsive microgels into fibres via colloidal electrospinning: experimental and statistical analysis. RSC Advances. 6:76370-76380.: The Royal Society of Chemistry AbstractWebsite

The strategy of confining stimuli-responsive microgels in electrospun fibres would allow the fabrication of polymeric networks that combine the microgels swelling ability and properties with the interest features of the electrospun fibres. Colloidal electrospinning is an emerging method in which fibres containing microgels can be produced by a single-nozzle and designed through the solution carrier materials. The incorporation of poly(N-isopropylacrylamide) (PNIPAAM) and PNIPAAM-chitosan (PNIPAAM-CS) in poly(ethyleneoxyde) (PEO) fibres via colloidal electrospinning producing composite fibres was the main purpose of the present work{,} which was confirmed by means of Scanning Electron Microscopy (SEM). Dynamic light scattering was used to analyse the microgels hydrodynamic diameter ranging up to 900 nm depending on the composition and temperature of the surrounding medium. By performing a statistical analysis the relationship of the processing variables over the fibre size was evaluated following the response surface methodology (RSM). From the set of parameters aimed to minimize the fibre diameter{,} composite fibres with an average diameter of 63 nm were produced. Only the as-prepared microgels with higher monodispersity provided {"}bead-on-a-string{"} morphologies.

Echeverria, C, Fernandes SN, Almeida PL, Godinho MH.  2016.  Effect of cellulose nanocrystals in a cellulosic liquid crystal behaviour under low shear (regime I): Structure and molecular dynamics. European Polymer Journal. 84:675-684. AbstractWebsite

In the field of cellulosic liquid crystals, attempts to establish the relationship between structure/properties have been developed. Above a critical concentration in an aqueous solution, hydroxypropylcellulose self-assembles in order to form cholesteric liquid crystal phases (LC-HPC). In this work we aim to understand how the incorporation of a low content of cellulose nanocrystals (CNC) within LC-HPC/H2O (50 wt%), could influence the behaviour of the system when subjected to low shear rates, where the cholesteric phase still persists. The analysis of the deuterium spectrum and the T2 (transversal relaxation) values confirm that the mobility of LC-HPC at low shear rates is restricted due to CNC, and consequently so is the flow of the cholesteric polydomains. These effects are more evident in the LC-HPC sample containing 2 wt% of CNC; besides needing more strain units to induce some degree of order, the achieved degree of order is recovered faster when compared to the reference sample.

Yang, Y, Wikieł AJ, Dall'agnol LT, Eloy P, Genet MJ, Moura JJG, Sand W, Dupont-Gillain CC, Rouxhet PG.  2016.  Proteins dominate in the surface layers formed on materials exposed to extracellular polymeric substances from bacterial cultures. Biofouling. 32:95-108.
Santos, L, Silveira CM, Elangovan E, Neto JP, Nunes D, Pereira L, Martins R, Viegas J, Moura JJG, Todorovic S, Almeida MG, Fortunato EM.  2016.  Synthesis of WO3 nanoparticles for biosensing applications. Sensors and Actuators B: Chemical. 223:186-194.
Esteves, T, Viveiros R, Bandarra J, Heggie W, Casimiro T, Ferreira FC.  2016.  Molecularly imprinted polymer strategies for removal of a genotoxic impurity, 4-dimethylaminopyridine, from an active pharmaceutical ingredient post-reaction stream. Separation and Purification Technology. 163:206-214. AbstractWebsite
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2015
Corvo, MC, Sardinha J, Casimiro T, Marin G, Seferin M, Einloft S, Menezes SC, Dupont J, Cabrita EJ.  2015.  {A Rational Approach to CO2 Capture by Imidazolium Ionic Liquids: Tuning CO2 Solubility by Cation Alkyl Branching}, {JUN 8}. ChemSusChem. 8:1935-1946., Number {11} Abstract

Branching at the alkyl side chain of the imidazolium cation in ionic liquids (ILs) was evaluated towards its effect on carbon dioxide (CO2) solubilization at 10 and 80bar (1bar=1x10(5)Pa). By combining high-pressure NMR spectroscopy measurements with molecular dynamics simulations, a full description of the molecular interactions that take place in the IL-CO2 mixtures can be obtained. The introduction of a methyl group has a significant effect on CO2 solubility in comparison with linear or fluorinated analogues. The differences in CO2 solubility arise from differences in liquid organization caused by structural changes in the cation. ILs with branched cations have similar short-range cation-anion orientations as those in ILs with linear side chains, but present differences in the long-range order. The introduction of CO2 does not cause perturbations in the former and benefits from the differences in the latter. Branching at the cation results in sponge-like ILs with enhanced capabilities for CO2 capture.

Santos, L, Wojcik P, Pinto JV, Elangovan E, Viegas J, Pereira LÍ, Martins R, Fortunato E.  2015.  {Structure and Morphologic Influence of WO 3 Nanoparticles on the Electrochromic Performance of Dual-Phase a -WO 3 /WO 3 Inkjet Printed Films}, feb. Advanced Electronic Materials. 1:n/a–n/a., Number 1-2 AbstractWebsite
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Echeverria, C, Aguirre LE, Merino EG, Almeida PL, Godinho MH.  2015.  Carbon Nanotubes as Reinforcement of Cellulose Liquid Crystalline Responsive Networks. ACS Appl Mater Interfaces. 7:21005-9., Number 38 AbstractWebsite

The incorporation of small amount of highly anisotropic nanoparticles into liquid crystalline hydroxypropylcellulose (LC-HPC) matrix improves its response when is exposed to humidity gradients due to an anisotropic increment of order in the structure. Dispersed nanoparticles give rise to faster order/disorder transitions when exposed to moisture as it is qualitatively observed and quantified by stress-time measurements. The presence of carbon nanotubes derives in a improvement of the mechanical properties of LC-HPC thin films.

Echeverria, C, Almeida PL, Feio G, Figueirinhas JL, Godinho MH.  2015.  A cellulosic liquid crystal pool for cellulose nanocrystals: Structure and molecular dynamics at high shear rates. European Polymer Journal. 72:72-81. AbstractWebsite

Cellulose and its derivatives, such as hydroxypropylcellulose (HPC) have been studied for a long time but they are still not well understood particularly in liquid crystalline solutions. These systems can be at the origin of networks with properties similar to liquid crystalline (LC) elastomers. The films produced from LC solutions can be manipulated by the action of moisture allowing for instance the development of a soft motor (Geng et al., 2013) driven by humidity. Cellulose nanocrystals (CNC), which combine cellulose properties with the specific characteristics of nanoscale materials, have been mainly studied for their potential as a reinforcing agent. Suspensions of CNC can also self-order originating a liquid-crystalline chiral nematic phases. Considering the liquid crystalline features that both LC-HPC and CNC can acquire, we prepared LC-HPC/CNC solutions with different CNC contents (1,2 and 5 wt.%). The effect of the CNC into the LC-HPC matrix was determined by coupling rheology and NMR spectroscopy - Rheo-NMR a technique tailored to analyse orientational order in sheared systems. (C) 2015 Elsevier Ltd. All rights reserved.

Tempera, C, Franco R, Caro C, André V, Eaton P, Burke P, Hänscheid T.  2015.  Characterization and optimization of the haemozoin-like crystal (HLC) assay to determine Hz inhibiting effects of anti-malarial. Malaria Journal. 14:403.
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