Dietary flavonoids exhibit many biologically-relevant functions and can potentially have beneficial effects in the treatment of pathological conditions. In spite of its well known antioxidant properties, scarce structural information is available on the interaction of flavonoids with membrane receptors. Advances in the structural biology of a specific class of membrane receptors, the G protein-coupled receptors, have significantly increased our understanding of drug action and paved the way for developing improved therapeutic approaches. We have analyzed the effect of the flavonoid quercetin on the conformation, stability and function of the G protein-coupled receptor rhodopsin, and the G90V mutant associated with the retinal degenerative disease retinitis pigmentosa. By using a combination of experimental and computational methods, we suggest that quercetin can act as an allosteric modulator of opsin regenerated with 9-cis-retinal and more importantly, that this binding has a positive effect on the stability and conformational properties of the G90V mutant associated with retinitis pigmentosa. These results open new possibilities to use quercetin and other flavonoids, in combination with specific retinoids like 9-cis-retinal, for the treatment of retinal degeneration associated with retinitis pigmentosa. Moreover, the use of flavonoids as allosteric modulators may also be applicable to other members of the G protein-coupled receptors superfamily.
Although carbon dioxide (CO2) is well known as one of the major green-house gases, it is also an economical C1 resource. Thus, CO2 has been regarded as an appealing starting material for the synthesis of polymers, like polycarbonates by the reaction with epoxides. Herein the reaction between natural epoxidized soybean oil (ESO), propylene oxide (PO) and CO2 under high pressure (4.0 MPa) with the presence of Co-Zn double metal cyanide (Co-Zn DMC) catalyst was studied. Temperature and reaction time were varied accordingly and the products obtained were characterized by FTIR, GPC and 1H NMR. The results obtained indicate the formation of polycarbonates in the samples collected with yields vary from 60 to 85%. The number average molecular weight (Mn) of the resultant polymer prepared at reaction temperature of 80 °C and reaction time of 6 h can reach up to 6498 g/mol.
Atout, H.; Alvarez , M.; Chebli, D.; Bouguettoucha, A.; Tichit, D.; Medina Cabello, Francisco; Llorca, J. Materials research bulletin Vol. 95, p. 578-587 DOI: 10.1016/j.materresbull.2017.08.029 Data de publicació: 2017-11 Article en revista
In this study, two different preparation methods of titanium dioxide nanoparticles/reduced graphene oxide nanocomposites were investigated using direct sol-gel method followed by hydrothermal treatment or simple hydrothermal route. A different amount of graphene (1- 20%) was mixed with TiO2 for both series of samples in order to improve the photocatalytic activity. The influence of the preparation method on the physico-chemical properties was established by different characterization methods and the photocatalytic degradation of methylene blue (MB) under UV light irradiation was used as test reaction. The highest photocatalytic activity was observed for the nanocomposites containing 10 wt% of graphene. The elimination of MB can reach 93% and 82% for the nanocomposites with 10 wt% graphene prepared by the sol-gel and hydrothermal methods, respectively. These photocatalysts are promising for practical application in nanotechnology.
Bacardit, A.; Mir, T.; Font Vallès, Joaquim; Cuadros, R.; Olle, L. Journal of the Society of Leather Technologists and Chemists Vol. 101, num. 5, p. 231-236 Data de publicació: 2017-10-04 Article en revista
This paper deals with the study of the physical, chemical and biological processes associated with the deterioration of wet-white leather. The samples of leather were exposed for eight months to outdoor weathering and then their properties were subsequently evaluated. The results indicate that resistance and dimensional stability of wet-white (THPS-syntan) leather is higher than that of chrometanned leather. The comparative work with chrome leather was described earlier.
Poly(ethylene succinate) (PES) with weight-average molecular weight above 60,000 g mol-1 was efficiently obtained by enzymatic ring opening polymerization of cyclic oligo(ethylene succinate)s c(ES)n, which in turn were prepared by lipase-catalysed cyclocondensation in solution of dimethyl succinate and ethylene glycol. The methodology was demonstrated to be also applicable to the synthesis of high molecular weight PES-copolyesters containing butylene succinate, e-hydroxycaproate or L-lactate units with a random distribution.
Medina , S.; Graells, M.; Guillén, G.; Espuña, A.; Puigjaner, L. Energy conversion and management Vol. 149, p. 722-737 DOI: 10.1016/j.enconman.2017.02.060 Data de publicació: 2017-10-01 Article en revista
Sustainable processes have recently awaked an increasing interest in the process systems engineering literature. In industry, this kind of problems inevitably required a multi-objective analysis to evaluate the environmental impact in addition to the economic performance. Bio-based processes have the potential to enhance the sustainability level of the energy sector. Nevertheless, such processes very often show variable conditions and present an uncertain behavior. The approaches presented for solving multi-objective problems under uncertainty have neglected the potential effects of different quality streams on the overall system. Here, it is presented an alternative approach, based on a State Task Network formulation, capable of optimizing under uncertain conditions, considering multiple selection criteria and accounting for the material quality effect. The resulting set of Pareto solutions are then assessed using the Elimination and Choice Expressing Reality-IV method, which identify the ones showing better overall performance considering the uncertain parameters space
Several methodologies, based on different thermodynamic assumptions and requiring substance properties and thermodynamic data, have been proposed in the literature for the prediction of the mechanical energy released by a Boiling Liquid Expanding Vapour Explosion (BLEVE) and the associated overpressure. A new method, simple and easy to use, is presented which only requires the vessel filling degree and the temperature at failure as input variables to estimate this energy. The polynomial approach has been used to obtain the equation corresponding to the diverse substances most commonly involved in these explosions. The comparison of the predicted values with experimental data shows a good agreement.
Das, D.; Pal, K.; Llorca, J.; Dominguez, M.; Colussi, S.; Trovarelli, A.; Gayen, A. Reaction kinetics mechanisms and catalysis Vol. 122, num. 1, p. 135-153 DOI: 10.1007/s11144-017-1228-5 Data de publicació: 2017-10-01 Article en revista
A series of Pd-supported metal oxides (Al2O3, Fe2O3 and CeO2) have been prepared by a single step solution combustion synthesis (SCS) method. Their catalytic performance was evaluated for the selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HCAL) under atmospheric pressure of hydrogen at 100 °C. Among these materials, combustion synthesized Pd (2 at.%)/Al2O3 catalyst exhibits the highest CAL conversion (69%) with complete HCAL selectivity. The analogous catalyst prepared by the incipient wetness impregnation (IWI) method shows an initially similar activity. X-ray diffraction and high resolution transmission electron microscopy analyses of the as prepared SCS sample show fine dispersion of PdO over the ¿-Al2O3 support. On ageing, a major portion of PdO is reduced to metallic Pd (Pd2+:Pd0 = 36:64 for the SCS catalyst and Pd2+:Pd0 = 26:74 for the IWI catalyst from X-ray photoelectron spectroscopy studies) suggesting comparatively more ionic character of palladium in the SCS catalyst. In the hydrogen atmosphere, without distinguishing the reductive pretreatment of catalyst and the beginning of hydrogenation subsequent to CAL addition, the Pd-species undergoes rearrangement to form a core–shell like structure of Pd (core)–PdO (periphery) covered with alumina layer, bringing in additional stability to the Pd-species in the SCS catalyst and making it highly recyclable. The analogous IWI catalyst, on the contrary, contains a mixed Pd–PdO ensemble that does not increase the stability causing continuous loss of activity in the consecutive cycles of hydrogenation.
This work presents the diagnosis procedure followed to determine the degree of damage of a 100-year-oldreinforced concrete building located in Barcelona city, the Sant-Manuel pavilion at Hôpital de la Santa Creui Sant-Pau. Some structural components of this building were affected by severe corrosion problems inthe reinforcing steel UPN profiles. In order to obtain a representative sample set, a preliminary inspectionof the macroscopic architectonic structure was applied at selected zones that exhibited the metallic back-bone. Gravimetric and electrochemical techniques have demonstrated that some UPN profiles presentedhigh corrosion rate. This was mainly due to the presence of water pipes installed beside the metallicstructure, which was a source of humidity, and also to the presence of calcium carbonate, calcium silicatehydrate, and calcium chloride substances inside the cement in direct contact with the metallic struc-tures, which were responsible for the steel depassivation. The work shows a practical example of howa suitable combination of chemical, physical and electrochemical techniques can be applied together tocharacterize a corrosion process, the obtained results validating and corroborating the prediction of thecorrosion rate in metallic structures.
Carrasco, F.; Santana, O.; Cailloux, J.; Sanchez-Soto, M.; Bou, J. J.; Maspoch, M. Congreso Interamericano de Computación Aplicada a la Industria de Procesos p. 943-952 Data de presentació: 2017-09-27 Presentació treball a congrés
En este trabajo se han fabrico, mediante extrusión reactiva, láminas de 1 mm de espesor de ácido poliláctico y de su nanocompuesto con un 2.5% en masa de montmorillonita organomodificada. En este proceso de extrusión reactiva se ha utilizado un extensor de cadena, al 0.5% en masa, con el fin de mejorar las propiedades de estos materiales. Se ha empleado la ecuación analítica general para evaluar los parámetros cinéticos de la descomposición térmica del PLA y de su nanocompuesto. Se han analizado diferentes mecanismos empíricos y teóricos de reacciones en estado sólido con el fin de elucidar cuál es el mejor modelo cinético. Para alcanzar este objectivo, se han construido las funciones de conversión estandarizadas, f(a)/f(0.5). Puesto que estas curvas patrón suministran información tan solo cualitativa, se ha propuesto un índice cuantitativo, basado en el error medio integral (EMI) entre los valores teóricos y experimentales de la función de conversión estandarizada. De esta forma, ha podido demostrase que el mejor modelo cinético teórico es el de escisión aleatoria de cadenas macromoleculares. La presencia de nanopartículas ha sido beneficiosa, al mejorar la resitencia a la degradación térmica del PLA.
Puiggali, A.; Micheletti, P.; Estrany, F.; del Valle, LJ.; Aleman, C. Advanced healthcare materials Vol. 6, num. 18, p. 1-11 DOI: 10.1002/adhm.201700453 Data de publicació: 2017-09-20 Article en revista
Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles are loaded with curcumin and piperine by in situ emulsion polymerization using dodecyl benzene sulfonic acid both as a stabilizer and a doping agent. The loaded drugs affect the morphology, size, and colloidal stability of the nanoparticles. Furthermore, kinetics studies of nonstimulated drug release have evidenced that polymer···drug interactions are stronger for curcumin than for piperine. This observation suggests that drug delivery systems based on combination of the former drug with PEDOT are much appropriated to show an externally tailored release profile. This is demonstrated by comparing the release profiles obtained in presence and absence of electrical stimulus. Results indicate that controlled and time-programmed release of curcumin is achieved in a physiological medium by applying a negative voltage of -1.25 V to loaded PEDOT nanoparticles.
En la última década, los polímeros conductores han despertado un gran interés tanto a nivel científico como tecnológico debido a las propiedades electroactivas que exhiben estos materiales. Por este motivo, en la presente Tesis Doctoral se han estudiado las aplicaciones de algunos de estos polímeros conductores, principalmente derivados del politiofeno, en el ámbito de la biomedicina y la biotecnología.Según los objetivos propuestos en esta Memoria, inicialmente se han realizado estudios relacionados con la preparación y caracterización de copolímeros de injerto empleando macromonómeros formados por oligotiofenos, a los que se les ha incorporado una cadena de polietilenglicol de peso molecular definido. Seguidamente se ha investigado su comportamiento mediante ensayos de citotoxicidad, adhesión celular y proliferación celular.A continuación, se ha realizado la síntesis y la caracterización de híbridos polímero conductor-péptido. Inicialmente, se ha optimizado el método de preparación de estos materiales empleando sistemas modelo, en los que el péptido ha sido re-emplazado por un amino ácido diseñado por similaridad química. Una vez evaluadas las diferentes estrategias sintéticas, se han obtenido híbridos formados por el mismo polímero y el péptido RG*D, donde RG*D es una secuencia análoga a la RGD (Arg-Gly-Asp) en la que el residuo central se ha sustituido por el amino ácido mencionado anteriormente. Para estos materiales se ha evaluado la biocompatibilidad y la bioactividad.La última parte de esta Tesis está orientada a la encapsulación de biomoléculas de pequeño tamaño en nanoestructuras poliméricas que pueden ser empleadas como sistemas transportadores y sistemas de liberación controlada cuando se incorporan al organismo. Los estudios se han iniciado encapsulando diferentes amino ácidos y se han acabado con péptidos hidrofóbicos lineales y cíclicos. En todos los casos la encapsulación se ha llevado a cabo mediante electrospraying o electrospinning.Los resultados obtenidos en esta Tesis se recogen en las siguientes publicaciones:- "Polythiophene-g-poly(ethylene glycol) Graft Copolymers from Electroactive Scaffolds".A.-D. Bendrea, G. Fabregat, J. Torras, S. Maione, L. Cianga, L. J. del Valle, I. Cianga & C. Alemán. J. Mater. Chem. B 2013, 1, 4135-4145.- "Effect of the Graft Ratio on the Properties of Polythiophene-g-poly(ethylene glycol)".S. Maione, G. Fabregat, L. J. del Valle, A.-D. Bendrea, L. Cianga, I. Cianga, F. Estrany & C. Alemán. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 239-252.- "Electro-Biocompatibility of Conjugates Designed by Chemical Similarity".S. Maione, G. Fabregat, L. J. del Valle, G. Ballano, C. Cativiela & C. Alemán. J. Pept. Sci. 2014, 20, 537-546.- "Electroactive Polymer-Peptide Conjugates for Adhesive Biointerfaces".S. Maione, A. M. Gil, G. Fabregat, L. J. del Valle, J. Triguero, A. Laurent, D. Jacquemin, F. Estrany, A. I. Jiménez, D. Zanuy, C. Cativiela & C. Alemán. Biomater. Sci. 2015, 3, 1395-1405.- Electrospray Loading and Release of Hydrophobic Gramicidin in Polyester Microparticles".S. Maione, L. J. del Valle, M. M. Pérez-Madrigal, C. Cativiela, J. Puiggalí & C. Alemán. RSC Adv. 2016, 6, 69634-69640.- "Biodegradable Nanofibrous Scaffolds as Smart Delivery Vehicles for Amino Acids".S. Maione, M. M. Pérez-Madrigal, L. J. Del Valle, A. Díaz, L. Franco, C. Cativiela, J. Puiggalí & C. Alemán. J. Appl. Polym. Sci. 2017, 134, 44883 (1-14).
Aguilo, E.; Soler, L.; Casanovas, A.; Moro, A.; Lima, J.C.; Rodríguez, L.; Llorca, J. ChemCatChem Vol. 9, num. 17, p. 3289-3292 DOI: 10.1002/cctc.201700518 Data de publicació: 2017-09-08 Article en revista
The integration of TiO2 with a AuI complex containing a thiocoumarin moiety resulted in a very efficient photocatalyst for the generation of H2. The molecular structure of the complex was preserved under the photoreaction owing to the strong AuI-S bond. The AuI complex played a determinant role in the photogeneration of H2 by accepting the photoinduced electrons originated in TiO2 upon light exposure. This is the first example of a AuI complex semiconductor hybrid photocatalyst. The rate of H2 generation under dynamic conditions from water/ethanol is approximately one order of magnitude superior on a metal basis to that obtained over conventional TiO2 decorated with Au metal nanoparticles.
Lipoxygenases (LOXs) are nonheme iron-containing enzymes catalyzing the dioxygenation of polyunsaturated fatty acids. LOX catalytic activity depends on the presence of iron in the active site and the iron removal is also able to affect the membrane binding properties of the enzyme. Leukotrienes biosynthesis is initiated by the action of 5-LOX at the level of nuclear membrane and the mechanism of enzyme-membrane interaction is thought to involve structural flexibility and conformational changes at the level of the protein tertiary structure. In this study, we have analyzed by molecular dynamics simulations the conformational changes induced by iron removal in 5-LOX. The data indicate that the degree of enzyme flexibility is related to the presence of iron into the active site that is able to stabilize the protein increasing its rigidity. These findings provide further evidence that the conformation and the functional activity of LOXs is tuned by the presence of iron at the active site, suggesting new approaches for the design of enzyme inhibitors.
Márquez, Y.; Graupera, J.; del Valle, LJ.; Turon, P.; Franco, L.; Puiggali, J. Express polymer letters Vol. 11, num. 9, p. 674-689 DOI: 10.3144/expresspolymlett.2017.66 Data de publicació: 2017-09-01 Article en revista
Poly(e-caprolactone) (PCL) films reinforced with polylactide (PLA) microfibers were prepared by two methodologies: a) melt pressing of an electrospun PLA mat between two PCL films, and b) melt pressing of a co-electrospun mat composed of PLA microfibers and PCL nanofibers. Electrospinning conditions were selected for each polymer to obtain films loaded with 10, 20 and 30 wt% of PLA. Thermal and mechanical properties varied depending on the preparation method. Thus, PLA crystallinity was higher when films were obtained by the co-electrospinning process, as revealed from DSC and synchrotron X-ray diffraction data since cold crystallization of the highly oriented PLA microfibers was favored in the subsequent heating run when they were in close contact with PCL nanofibers. Samples obtained by co-electrospinning also showed higher mechanical properties (e.g. Young modulus) with increasing PLA load. In this case, fracture surfaces showed significant interactions between fibers and the PCL matrix and decreased fiber pull-out.
All fabrics were also loaded with chlorhexidine (CHX) as a hydrophilic bactericide agent. A delayed release was observed when the drug was only loaded into the electrospun PLA microfibers, and diffusion varied with the method of preparation. In all cases, samples had a clear bactericide effect against Gram positive and Gram negative bacteria. Nevertheless, the protective effect was slightly lower when CHX was only loaded in the reinforcing PLA microfibers.
Zhu, Y.; Ahmad, M.; Yang, L.; Misovich, M.; Yaroshchuk, A.; Bruening, M.L. Journal of membrane science Vol. 537, p. 1-9 DOI: 10.1016/j.memsci.2017.05.043 Data de publicació: 2017-09-01 Article en revista
Nafion membranes coated with polyelectrolyte multilayers (PEMs) exhibit outstanding monovalent/divalent cation electrodialysis selectivity in a single-membrane cell. Nevertheless, the high cost of Nafion and the extensive pretreatments required for polyelectrolyte adsorption on this surface may preclude the use of these membranes in many applications. This work reports that native aliphatic polyamide Fujifilm type 1 cation-exchange membranes modified with protonated poly(allylamine) (PAH)/poly (4-styrenesulfonate) (PSS) films also show extremely high K+/Mg2+ cation selectivities in ED with a single-membrane cell. Even with 0.1 M salt in the source phase, the K+/Mg2+ selectivity is >1000. The very low transfer of divalent cations implies that the PEM forms a complete, continuous coating on the smooth Fujifilm surface. Moreover, for a membrane coated on both sides, the PEM on the anode side is responsible for most of the selectivity. However, the current efficiency is only ~0.6 for PAH/PSS-modified Fujifilm or Nafion membranes. Adsorption of highly water-swollen (PDADMAC/PSS)n films on Nafion membranes leads to high K+/Mg2+ and Li+/Co2+ selectivities in ED, and the monovalent cation current efficiency reaches 0.8.
Pappacena, A.; Rancan, M.; Armelao, L.; Llorca, J.; Ge, W.; Ye, B.; Lucotti, A.; Trovarelli, A.; Boaro, M. Journal of Physical Chemistry C Vol. 121, num. 33, p. 17746-17755 DOI: 10.1021/acs.jpcc.7b06043 Data de publicació: 2017-08-24 Article en revista
The reactivity of a ceria-rich Ce0.85Zr0.15O2 solid solution toward the thermochemical water splitting process (TWS) was studied over repeated H2/H2O redox cycles. The structural and surface modifications after treatment at high temperature under air or N2 atmospheres were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and positron annihilation lifetime spectroscopy (PALS). Samples treated under nitrogen resulted more active due to phase segregation with formation of a zirconyl oxynitride phase in catalytic amount. Insertion of N3- into the structure contributes to an increase in the numbers of oxygen vacancies that preferably arrange in large clusters, and to the stabilization of Ce3+ centers on the surface. In comparison, treatment under air resulted in a different arrangement of defects with less Ce3+ and smaller and more numerous vacancy clusters. This affects charge transfer and H-coupling processes, which play an important role in boosting the rate of H2 production. The behavior is found to be only slightly dependent on the starting ceria-zirconia composition, and it is related to the development of a similar surface heterostructure configuration, characterized by the presence of at least a ceria-rich solid solution and a (cerium-doped) zirconyl oxynitride phase, which is supposed to act as a promoter for TWS reaction. The above findings confirm the importance of a multiphase structure in the design of ceria-zirconia oxides for water splitting reaction and allow a step forward to find an optimal composition. Moreover, the results indicate that doping with nitrogen might be a novel approach for the design of robust, thermally resistant, and redox active materials.
Trypanosoma brucei, the causative agent of sleeping sickness (Human African Trypanosomiasis, HAT), contains a kinetoplast with the mitochondrial DNA (kDNA), comprising of >70% AT base pairs. This has prompted studies of drugs interacting with AT-rich DNA, such as the N-phenylbenzamide bis(2-aminoimidazoline) derivatives 1 [4-((4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide dihydrochloride] and 2 [N-(3-chloro-4-((4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)-4-((4,5-dihydro-1H-imidazol-2-yl)amino)benzamide] as potential drugs for HAT. Both compounds show in vitro effects against T. brucei and in vivo curative activity in a mouse model of HAT. The main objective was to identify their cellular target inside the parasite. We were able to demonstrate that the compounds have a clear effect on the S-phase of T. brucei cell cycle by inflicting specific damage on the kinetoplast. Surface plasmon resonance (SPR)–biosensor experiments show that the drug can displace HMG box-containing proteins essential for kDNA function from their kDNA binding sites. The crystal structure of the complex of the oligonucleotide d[AAATTT]2 with compound 1 solved at 1.25 Å (PDB-ID: 5LIT) shows that the drug covers the minor groove of DNA, displaces bound water and interacts with neighbouring DNA molecules as a cross-linking agent. We conclude that 1 and 2 are powerful trypanocides that act directly on the kinetoplast, a structure unique to the order Kinetoplastida.
Despite GPCRs sharing a common seven helix bundle, analysis of the diverse crystallographic structures available reveal specific features that might be relevant for ligand design. Despite the number of crystallographic structures of GPCRs steadily increasing, there are still challenges that hamper the availability of new structures. In the absence of a crystallographic structure, homology modeling remains one of the important techniques for constructing 3D models of proteins. In the present study we investigated the use of molecular dynamics simulations for the refinement of GPCRs models constructed by homology modeling. Specifically, we investigated the relevance of template selection, ligand inclusion as well as the length of the simulation on the quality of the GPCRs models constructed. For this purpose we chose the crystallographic structure of the rat muscarinic M3 receptor as reference and constructed diverse atomistic models by homology modeling, using different templates. Specifically, templates used in the present work include the human muscarinic M2; the more distant human histamine H1 and the even more distant bovine rhodopsin as shown in the GPCRs phylogenetic tree. We also investigated the use or not of a ligand in the refinement process. Hence, we conducted the refinement process of the M3 model using the M2 muscarinic as template with tiotropium or NMS docked in the orthosteric site and compared with the results obtained with a model refined without any ligand bound.
Pérez-Madrigal, Maria M.; Torras, J.; Casanovas, J.; Häring, M.; Aleman, C.; Díaz-Díaz, D. Biomacromolecules Vol. 18, num. 9, p. 2967-2979 DOI: 10.1021/acs.biomac.7b00934 Data de publicació: 2017-08-11 Article en revista
This manuscript describes a new route to prepare rapidly Ca2+-free hydrogels from unmodified sodium alginate by simply mixing with small organic molecules such as poly(carboxylic acid) compounds as cross-linker agents instead of classical divalent metal salts such as CaCl2. Dimethyl sulfoxide (DMSO) was also found to induce the rapid gelation of aqueous alginate solutions. The gelation process takes place at room temperature, and depending on the composition, gels with good thermal (90-100 °C) and mechanical properties compared to classical metal-containing analogs are obtained. DMSO-based gels showed remarkable self-supporting and thixotropic properties, which can be tuned by the biopolymer concentration. Furthermore, oxalic acid-based gels show superior elasticity than HCl, CaCl2 and DMSO-based gels. The possibility to prepare monoliths, beads, and films of these gels provide them with significant versatility. In particular, films made of alginate and oxalic acid show good potential as synergistic anticancer drug delivery carrier. Computational studies using both quantum mechanical and classical force-field methodologies reveal that hydrogen bonding networks between water and DMSO molecules located close to the alginate chains are responsible for the stability of DMSO-based gels. In contrast, the cohesion of oxalic acid-based gels is a consequence of the coexistence of multiple ionic associations involving oxalate, alginate, and Na+ counterions, which stabilize the system and keep all the interacting species grouped.
Heidarzadeh, N.; Mehdi Rafizadeh, M.; Faramarz Afshar Taromi, F.; del Valle, LJ.; Franco, M.; Puiggali, J. Thermochimica acta Vol. 654, p. 101-111 DOI: 10.1016/j.tca.2017.05.011 Data de publicació: 2017-08-10 Article en revista
Thermal stability and degradation kinetics have been studied for a series of aliphatic-aromatic copolyesters where the terephthalate content was varied between 30 mol-% and 70 mol-%. Succinate, adipate and sebacate were considered as the aliphatic dicarboxylate unit. All copolyesters were synthesized with a perfect random distribution by a thermal transesterification process from the corresponding homopolyesters.
A complex degradation was deduced for all copolymers taking into account the increment of the activation energy with conversion. In fact, thermogravimetric curves showed a minor decomposition process in the low conversion region that was more significant for the succinate derivative and specifically for that having the lowest aromatic content. The sebacate derivative was characterized by the presence of an additional and minor decomposition process that took place at the highest conversion.
All copolyesters were defined by a major decomposition process, which has similar values of activation energy regardless of the method used to calculate them (e.g. Kissinger, KAS or Friedman methodologies). This decomposition reaction followed a A4 Avrami-Erofeev mechanism when Coats-Redfern and Criado methodologies were applied. In summary, all the studied copolymers thermally decompose following a complex process but in all cases the main degradation step corresponds to a similar degradation mechanism.
Ultrasound micro-molding technology was successfully applied to prepare nanocomposites based on a poly(e-caprolactone) (PCL) matrix and multi-walled carbon nanotubes (MWCNTs). Optimization of processing parameters (i.e. amplitude, force and time) was crucial to obtain nanocomposites without any evidence of degradation, high material saving and short processing time (7–8 s). Good dispersion of nanotubes was achieved after processing previously formed solvent casting films. This dispersion was even partially detected in pieces directly obtained from powder mixtures of both components. Incorporation of MWCNTs had a remarkable influence on melting and crystallization processes, which were systematically studied by time resolved synchrotron experiments. Results indicated higher melting and crystallization temperatures for the nanocomposite, with temperature differences higher than 5 °C. Carbon nanotubes were effective nucleating agents and had an influence on crystallinity, crystallization rate and even on lamellar morphology, which was evaluated by analysis of the correlation function of small angle diffraction profiles. Crystallinity within lamellar stacks was lower for the solvent casting nanocomposite, but in this case lamellae underwent a thickening process during heating that accounted for the increase in the melting temperature. Crystallization from the melt rendered similar lamellar morphologies at the end of the process due to a lamellar insertion mechanism.
Escherichia coli (E. coli) strains are among the most frequently isolated microorganisms in urinary tract infections able to colonize the surface of urinary catheters and form biofilms. These biofilms are highly resistant to antibiotics and host immune system, resulting in increased morbidity and mortality rates. Strategies to prevent biofilm development, especially via restricting the initial stages of bacteria attachment are therefore urgently needed. Herein, a common urinary catheter material – polydimethylsiloxane (PDMS) – was covalently functionalized with antibacterial aminocellulose nanospheres (ACNSs) using the epoxy/amine grafting chemistry. The PDMS surface was pre-activated with (3-glycidyloxypropyl)-triethoxysilane to introduce epoxy functionalities prior to immobilization of the intact ACNSs via its amino groups. The AC biopolymer was first sonochemically processed into NSs improving by up to 80% its potential to prevent the E. coli biofilm formation on a polystyrene surface. The silicone surface decorated with these NSs demonstrated efficient inhibition of E. coli biofilms, reducing the total biomass when compared with pristine silicone material. Therefore, the functionalization of silicone-based materials with ACNSs shows promise as potential platform for prevention of biofilm-associated infections caused by E. coli.
This work reports on a green synthetic route to produce concentrated aqueous dispersions of silver nanoparticles (AgNP)
employing high-intensity ultrasound (US) and chitosan (CS) as a non-toxic reducing agent for Ag1 salts and AgNP stabilizer. The sonication simultaneously boosted the synthesis and improved the stability of the AgNP, capping them with CS. Hybrid AgNP-CS antimicrobial dispersions, stable for at least 6 months, were synthesized in a simple single step process. The use of US allowed for applying relatively mild processing temperatures (608C) and reaction time between 30 min and 3 h to obtain concentrated disper- sions of AgNP that otherwise could not be obtained even after 72 h under mechanical stirring at the same reaction conditions. Upon sonication spherical AgNP-CS with a size between 60 and 100 nm were generated, in contrast to the average diameter of 200 nm of the particles obtained by stirring. The antibacterial efficiency of the AgNP-CS hybrids was evaluated against the medically relevant pathogens Staphylococcus aureus and Escherichia coli. The US-synthesized AgNP-CS showed more than 3-fold higher antibacterial activity compared to the particles obtained under stirring, due to their higher concentration and smaller size.
Gimenez, F.; Espriu-Gascon, A.; Bastos-Arrieta, J.; Pablo, J. Journal of Archaeological Science: Reports Vol. 14, p. 174-180 DOI: 10.1016/j.jasrep.2017.05.055 Data de publicació: 2017-08-01 Article en revista
The effect of the presence of NaCl on the synthesis of Egyptian blue pigment (cuprorivaite, CaCuSi4O10) was studied through experiments in which different amounts of NaCl were introduced in the initial mixture of reactants. The solids synthesized were characterized by X-ray Diffraction, Field Emission Scanning Electron Microscopy (FE-SEM) coupled to Energy-Dispersive Spectrometry (EDS) and High Resolution Transmission Electron Microscopy (HR-TEM) coupled to EDS. The main result of the experiments was that Egyptian blue formation was inhibited in the presence of NaCl, actually, almost no cuprorivaite was found in > 10% NaCl experiments and the solids synthesized in NaCl were always green instead of the characteristic blue of the Egyptian blue pigment. The solids synthesized in the presence of NaCl, a mixture of wollastonite (CaSiO3) and a Cu-rich amorphous phase, probably corresponded to the composition of the pigment known as Egyptian green. Considering the usual presence of NaCl on some of the raw materials used for the pigment fabrication, Egyptian artisans had to be very careful on selecting the reactants for the fabrication of the pigment (quartz would be much more suitable than Egyptian sand, and ash plants than natron) or they incorporated a process of purification of the reactants in order to eliminate chlorides prior to the synthesis.
Composites formed by poly(3,4-ethylenedioxythiophene) and alumina (PEDOT/Al2O3) have been prepared by in situ anodic polymerization. For this purpose, the stability of 1:1 and 4:1 monomer:alumina aqueous solutions has been examined as a function of the pH (2.3, 4.0, 7.0, 8.8, or 10.8). Results indicate that the monomer behaves as a dispersant that remains stable at the studied basic pHs despite they are close to the isoelectric point of alumina. Although the thermal stability of the composites is considerably affected by the pH of the reaction medium, its influence on the surface morphology is very small. Independently, of the synthetic conditions, the electrochemical properties were better for PEDOT/Al2O3 than for pure PEDOT, reflecting that alumina particles promote the charge mobility. The highest specific capacitance (SC; 141 F/g), which was 55% higher than that obtained for pure PEDOT, was achieved for the composite prepared at pH¿=¿8.8 using a 4:1 monomer:alumina ratio. These conditions favor the participation of OH– groups as secondary doping agents without degrading the polymer matrix and enhance the specific surface of the films, facilitating the ionic mobility. On the other hand, application of a multi-step polymerization strategy has shown that interfaces originated by consecutive steps enhance the SC.
Gloss is a critical issue in many applications in the coating industry. Gloss depends on optical and rheological properties of complex mixtures, and estimating gloss from basic properties is still a challenge. In order to predict the gloss of an industrial thickened-to-application formulation this work presents a gloss-rheology semi empirical-modeling approach based on a gloss excess function and previous work from other authors. A new matt (low gloss) hybrid waterborne polyurethane dispersion composed out of a self-matting agent (A) and a traditional silica-based matting agent (B) has been studied, and the resulting gloss of the mixture has been correlated to pure component gloss values and dynamic viscosity at medium shear rate. Several modeling options have been tested and their goodness of fit has been determined. The most promising options have been selected and validated towards untrained data sets.
Viader, G.; Casal, O.; Licon, E.; Lefevre, B.; de Arespacochaga, N.; Echevarria, C.; Valderrama, C.; Cortina, J. International Congress on Membranes and Membrane Processes p. 1 Data de presentació: 2017-07-29 Presentació treball a congrés
Ferrer, O.; Pastur, M.; Aceves, M.; Gómez, C.; Mateo, A.; Ayuso, A.; Mesa, C.; Vega, A.; Cortina, J. International Congress on Membranes and Membrane Processes p. 1-2 Data de presentació: 2017-07-29 Presentació treball a congrés
Lopez, J.; Reig, M.; Vecino, X.; Valderrama, C.; Gibert, O.; Yaroshchuk, A.; Cortina, J. International Congress on Membranes and Membrane Processes Data de presentació: 2017-07-29 Presentació treball a congrés
In order to make decisions efficiently and equitably, up-to-date information is required. In developing countries, with limited resources, such information should be provided by means of cost-effective methodologies, in which sampling issues are of primary importance. Different sampling strategies are currently in use. At local level with reduced populations, standard approaches prove expensive and time consuming. In this paper, we opt for simple linear piecewise approximations to calculate the sample size in terms of given precision, confidence level and population size. To support the applicability of the proposed approach by practitioners in the field, easy-to-use tables are elaborated. In terms of sampling, easy-to-follow practical guidelines for household selection and transect walk planning are also provided. The article presents six rural communities in Honduras as initial case study to illustrate the validity and applicability of the approach adopted herein for sampling design and sample size determination.
Actualmente en España, las centrales nucleares están acumulando el combustible nuclear gastado (CNG) y apenas disponen de espacio suficiente para seguir almacenando el residuo generado por la actividad de la central. En consecuencia, es necesario adoptar una solución definitiva a la gestión de los residuos nucleares. La opción aceptada internacionalmente para almacenar definitivamente el CNG como la más segura y viable es el Almacenamiento Geológico Profundo (AGP) basado en el confinamiento y la protección del residuo mediante un sistema de multibarrera. Dicho sistema considera el CNG como primera barrera donde están contenidos los radionúclidos (RN) debido a las propiedades físicas y químicas del propio combustible.Con el objetivo de evaluar la seguridad del AGP y determinar el comportamiento del CNG en condiciones relevantes para su almacenamiento definitivo, en el presente trabajo se han planteado cuatro posibles escenarios que podrían provocar la alteración del combustible. Dichos escenarios se han estudiado mediante análogos no irradiados del CNG.En el proceso de alteración de las barreras que componen el AGP, la corrosión anaeróbica de la capsula metálica produce una elevada presión de hidrógeno que podría entrar en contacto con el CNG. A su vez, la entrada de agua en el repositorio y la temperatura a la que se encuentra el CNG podrían hacer aumentar la humedad en las proximidades del residuo. Por lo tanto, en este trabajo se ha estudiado el efecto del vapor de agua en contacto con el UO2 en atmósfera de H2. Los resultados obtenidos muestran que se produce la oxidación del uranio tanto en condiciones anaeróbicas como en condiciones reductoras en función de la temperatura usada. Por otro lado, en presencia de nanopartículas de paladio, análogas a las partículas épsilon del CNG, no se observó oxidación alguna del UO2 en presencia de H2.En el momento en que el agua entre en contacto con el CNG, los RN segregados de la matriz más volátiles y solubles serán lixiviados de forma prácticamente instantánea (IRF) provocando un aumento significativo de radiación en las aguas subterráneas. Con el objetivo de predecir la liberación de dichos RN se ha diseñado un modelo y un algoritmo matemático que ha permitido predecir la liberación de los RN disueltos en la matriz e identificar y cuantificar los RN que forman parte de la IRF de un combustible real. Los resultados obtenidos de la aplicación del modelo concuerdan con resultados experimentales publicados anteriormente. Por lo tanto, se puede concluir que el modelo y el algoritmo cumplen con los objetivos marcados de identificación, predicción y cuantificación de la distribución de los RN en el CNG.Debido a que los mecanismos de alteración del UO2 podrían variar dependiendo de la composición del agua subterránea, se ha estudiado la corrosión del CNG en contacto con aguas de cemento. Para ello se ha usado un electrodo de SIMFUEL con el que se han realizado ciclovoltamogramas, experimentos potenciostáticos y mediciones del potencial de corrosión en condiciones hiperalcalinas y en presencia de calcio y silicato como símil de aguas de cemento. Los resultados muestran una disminución de la corrosión en presencia de calcio y silicato que podría ser provocada por la precipitación de fases sólidas en la superficie del SIMFUEL o por la estabilización de las fases reducidas.Por último, la precipitación de fases sólidas podría ayudar a reducir la concentración de los RN liberados por el CNG. En este contexto, se han estudiado y determinado las capacidades de retención de dos fases sólidas de uranio; la soddiita y la uranofana, en contacto con Cs y Sr en disolución. Se ha determinado que ambos sólidos son capaces de adsorber ambos iones en su superficie, siendo la soddiita el sólido con mayor capacidad de retener Cs y la uranofana la fase sólida con mayor capacidad de retención de Sr. Por tanto, la formación de estas fases podría disminuir la concentración de estos RN liberados a la geosfera.
Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 h just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.
Carbon capture and storage (CCS) and carbon capture and utilisation (CCU) are acknowledged as important R&D priorities to achieve environmental goals set for next decades. This work studies biomass-based energy supply chains with CO2 capture and utilisation. The problem is formulated as a mixed-integer linear program. This study presents a flexible supply chain superstructure to answer issues on economic and environmental benefits achievable by integrating biomass-coal plants, CO2 capture and utilisation plants; i.e. location of intermediate steps, fraction of CO2 emissions captured per plant, CO2 utilisation plants' size, among others. Moreover, eventual incentives and environmental revenues will be discussed to make an economically feasible project. A large-size case study located in Spain will be presented to highlight the proposed approach. Two key scenarios are envisaged: (i) Biomass, capture or utilisation of CO2 are not contemplated; (ii) Biomass, capture and CO2 utilisation are all considered. Finally, concluding remarks are drawn.
Water, sanitation and hygiene (WaSH) are at the very core of sustainable development. As we embark on a new round of global goals to follow the 15 year Millennium Development Goals period, namely the Sustainable Development Goals, a top priority is to address a coherent framework for monitoring these services. In coming years, the sector will witness the development of a variety of multidimensional monitoring measures, albeit from different perspectives. This paper reviews three different multidimensional approaches that are increasingly adopted to determine the level of service delivered at the household. At the global level, a ladder approach to monitoring has been promoted by the WHO/UNICEF Joint Monitoring Programme. Alternatively, the use of aggregated indicators is widespread, as they are adequate to capture and simplify the complexity inherent in services delivery. Finally, the Alkire & Foster methodology for multidimensional poverty measurement has been extensively used for pro-poor targeting. We adapt this method to capture a set of direct household-related water and sanitation deprivations that batter a person at the same time. Taking the international post-2015 monitoring framework as a reference point, this article analyses these measures and their outcomes. For illustrative purposes, one small town in Mozambique is selected as initial case study. We conclude that multidimensional measures are needed to provide a complete picture of the context in which the WaSH services are delivered. In consequence, they are useful to report on the SDG monitoring architecture.
AUMENTO DE LA ELECTROACTIVIDAD DE FILMS DE POLI(N-METILPIRROL) POR INCORPORACIÓN DE NANOPARTÍCULAS DE TRIÓXIDO DE MOLIBDENO
Francesc Estrany1,3, Margarita Sanchez-Jiménez1, y Carlos Alemán2,3
1 Departament d’Enginyeria Química, E. U. d’Enginyeria Tècnica Industrial de Barcelona, Universitat Politècnica de Catalunya (U.P.C.), Comte d’Urgell 187, 08036 Barcelona, Spain. Email: firstname.lastname@example.org.
2 Departament d’Enginyeria Química, E. T. S. d’Enginyers Industrials, U. P. C., Diagonal 647, 08028, Barcelona, Spain. Email: email@example.com.
3 Center for Research in Nano-Engineering, U. P. C., Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona E-08028, Spain. Email: firstname.lastname@example.org.
El poli-(N-metilpirrol) (PNMPy), tiene importantes aplicaciones como la detección selectiva de dopa-mina1, dispositivos electrocrómicos2, y en la fabricación de supercapacitores3.
En el presente trabajo, se han electrogenerado films compuestos de poli(N-metilpirrol) por incorpora-ción de partículas de MoO3, trabajando a potencial constante de 1,40 V durante 180s, a partir de una solución 10 mM de NMPy y 0,1 M de LiClO4, con 10% (sobre peso de monómero) de partículas del óxido en suspensión estable. Como disolvente se ha empleado una mezcla 75:25 acetonitrilo:agua para favorecer la suspensión y formación de films uniformes de PNMPy/MoO3. El resto de condicio-nes de trabajo aparecen en trabajos previos1,3. La respuesta eléctrica de los films se ha caracterizado por voltamperometría cíclica (solución 0,1 M de LiClO4 en acetonitrilo), y se ha realizado el análisis morfológico (SEM) y micro- y nanotopográfico (AFM) de su superficie (Fig. 1). El análisis elemental EDX de los films ha probado la presencia de partículas de MoO3 en los films de PNMPy.
Fig. 1. Imágenes 3D de AFM de (a) PNMPy y (b)
Nanocompuesto PNMPy/(10%) MoO3
Se ha constatado un aumento de la capacidad redox de almacenamiento de carga de los films de PNMPy, al formar el nanocompuesto por incorporación de las nanopartículas de MoO3. Este positivo efecto se ha relacionado con una mayor apertura de la superficie interfacial film-electrolito en el nanocompuesto, lo que está concordancia con los resultados del análisis nanotopográfico realizado.
Los autores agradecen al MINECO la financiación recibida del Proyecto: MAT2015-69367-R.
1. G. Fabregat, J. Casanovas, E. Redondo, E. Armelin y C. Alemán. Phys. Chem. Chem. Phys., 2014,16, 7850-7861.
2. S. Ahmad y S. Singh. Electrochem. Commun., 2008, 10, 895-898.
3. D. Aradilla, F. Estrany y Carlos Alemán. J. Phys. Chem. C, 2011, 115, 8430-8438
Perez, J.; Pérez, Y.; Gómara, M.; Yuste, E.; Gomez-Gutierrez, P.; Haro, I. Chemistry - A European Journal Vol. 23, p. 11703-11713 DOI: 10.1002/chem.201702531 Data de publicació: 2017-07-03 Article en revista
Previous studies support the hypothesis that the envelope GB virus C (GBV-C) E1 protein interferes the HIV-1 entry and that a peptide, derived from the region 139-156 of this protein, has been defined as a novel HIV-1 entry inhibitor. In this work, we firstly focus on the characterization of the structural features of this peptide, which are determinant for its anti-HIV-1 activity and secondly, on the study of its interaction with the proposed viral target (i.e., the HIV-1 fusion peptide). We report the structure of the peptide determined by NMR spectroscopy in dodecylphosphocholine (DPC) micelles solved by using restrained molecular dynamics calculations. The acquisition of different NMR experiments in DPC micelles (i.e., peptide-peptide titration, diffusion NMR spectroscopy, and addition of paramagnetic relaxation agents) allows a proposal of an inhibition mechanism. We conclude that a 18-mer peptide from the non-pathogenic E1 GBV-C protein, with a helix-turn-helix structure inhibits HIV-1 by binding to the HIV-1 fusion peptide at the membrane level, thereby interfering with those domains in the HIV-1, which are critical for stabilizing the six-helix bundle formation in a membranous environment.
ABA triblock copolyesters were synthesized by ring-opening polymerization (ROP) of l-lactide in solution initiated by a telechelic d-glucose-based polyester macroinitiator. The macroinitiator with a number-average molecular weight about 2500 g mol-1 was synthesized by non-stoichiometric polycondensation in the melt of 2,4:3,5-di-O-methylene-d-glucitol and dimethyl succinate. Two triblock copolyesters of Mn ranging between ~6000 and ~9000 g mol-1, and differing in the length of the polylactide blocks were prepared. These copolyesters started to decompose when heated at ~220 °C and degraded slowly upon aqueous incubation under physiological conditions. They did not display any perceivable crystallinity and showed a single glass transition temperature (Tg) around 60 °C with the higher value corresponding to the larger content in glucitol units. The copolyesters were able to form nanoparticles with average diameters of ~100–130 nm and satisfactory dispersity. The effect of the block lengths on size, ¿-potential values and physical stability of the nanoparticles was evaluated. A molecular dynamics simulation study allowed modelling the two-phase structure of the nanoparticles and evidenced the preference of the glucose-based block to be peripherally located.
At a global level, access to safe drinking water and sanitation has been monitored by the Joint Monitoring Programme (JMP) of WHO and UNICEF. The methods employed are based on analysis of data from household surveys and linear regression modelling of these results over time. However, there is evidence of non-linearity in the JMP data. In addition, the compositional nature of these data is not taken into consideration. This article seeks to address these two previous shortcomings in order to produce more accurate estimates.
We employed an isometric log-ratio transformation designed for compositional data. We applied linear and non-linear time regressions to both the original and the transformed data. Specifically, different modelling alternatives for non-linear trajectories were analysed, all of which are based on a generalized additive model (GAM).
Results and discussion
Non-linear methods, such as GAM, may be used for modelling non-linear trajectories in the JMP data. This projection method is particularly suited for data-rich countries. Moreover, the ilr transformation of compositional data is conceptually sound and fairly simple to implement. It helps improve the performance of both linear and non-linear regression models, specifically in the occurrence of extreme data points, i.e. when coverage rates are near either 0% or 100%.
Ramos-Romero, S.; Hereu, M.; Molinar, E.; Almajano, María Pilar; Mendez, L.; Medina, I.; Taltavull, N.; Romeu, M.; Nogués, M.; Torres, J. Food research international Vol. 97, p. 364-371 DOI: 10.1016/j.foodres.2017.04.024 Data de publicació: 2017-07 Article en revista
¿-3 Polyunsaturated fatty acids (PUFAs) reduce risk factors for cardiovascular diseases (CVD) and other pathologies that involve low-grade inflammation. They have recently been shown to exert complementary functional effects with proanthocyanidins. As the reduction of health-promoting gut bacteria such as lactobacilli and bifidobacteria has been linked to a number of alterations in the host, the aim of this study was to determine whether PUFAs and proanthocyanidins also cooperate in maintaining well-balanced microbiota. To this end, rats were supplemented for 6 months with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) 1:1 (16.6 g/kg feed); proanthocyanidin-rich grape seed extract (GSE, 0.8 g/kg feed); or both. Plasma adiponectin, cholesterol, and urine nitrites were measured. Gut bacterial subgroups were evaluated in fecal DNA by qRT-PCR. Short-chain fatty acids (SCFAs) were determined in feces by gas chromatography. Body and adipose tissue weights were found to be higher in the animals given ¿-3 PUFAs, while their energy intake was lower. Plasma cholesterol was lower in ¿-3 PUFA supplemented groups, while adiponectin and urine nitrites were higher. ¿-3 PUFAs reduced the population of Lactobacillales and L. acidophilus after 6 months of supplementation. GSE significantly reduced L. plantarum and B. longum. The combination of ¿-3 PUFAs and GSE maintained the health-promoting bacteria at levels similar to those of the control group. Acetic acid was increased by the ¿-3 PUFA individual supplementation, while the combination with GSE kept this value similar to the control value. In conclusion, while individual supplementations with ¿-3 PUFAs or GSE modify the populations of Lactobacillus, Bifidobacterium and microbial products (SCFAs), their combination maintains the standard proportions of these bacterial subgroups and their function while also providing the cardiovascular benefits of ¿-3 PUFAs.
Chemical pulp mills have a need to diversify their end-product portfolio due to the current changing bio-economy. In this study, the methane potential of brown, oxygen delignified and bleached pulp were evaluated in order to assess the potential of converting traditional fibers; as well as microcrystalline cellulose and filtrates; to energy. Results showed that high yields (380 mL CH4/gVS) were achieved with bleached fibers which correlates with the lower presence of lignin. Filtrates from the hydrolysis process on the other hand, had the lowest yields (253 mL CH4/gVS) due to the high amount of acid and lignin compounds that cause inhibition. Overall, substrates had a biodegradability above 50% which demonstrates that they can be subjected to efficient anaerobic digestion. An energy and cost estimation showed that the energy produced can be translated into a significant profit and that methane production can be a promising new alternative option for chemical pulp mills.
Hydrogenolysis of glycerol was studied using a diluted aqueous solution of glycerol in gas phase and atmospheric pressure on Ni/¿-Al2O3 catalyst. The catalytic transformation of glycerol generates products derived from dehydration, dehydrogenation, hydrogenolysis and condensation reactions. Deep hydrogenolysis route to produce CH4 prevails in the first few hours of reaction. As the reaction time progress, dehydration-dehydrogenation products start to appear. Here, a description of the deactivation sources and its effects on the catalytic performance of Ni catalyst was proposed. The catalyst was characterized before and after the catalytic reaction by high-resolution transmission electron microscopy (HRTEM) and by employing Fourier transformed infrared spectroscopy (FTIR) of adsorbed CO. A source of deactivation was due to carbonaceous deposition. FTIR at low CO dosing pressure reveal bands assignments species essentially due to linear and bridge carbonyls, whereas high pressure CO dosing produces a complex spectra due to polycarbonyls. X-ray absorption near edge structure (XANES) analysis was employed to reveal the initial degree of reduction of the fresh catalyst. The oxidation of metallic Ni in the course of reaction may also be considered as a source of deactivation. Ni oxide species promote dehydration routes. Alumina support facilitates nickel species to be more active toward interacting with glycerol. Dehydration, which takes place on the acid sites, is the mainly route related to the generation of carbon deposition and to the observed catalyst deactivation. Another source of deactivation was due to carbiding of Ni to form Ni3C. The regeneration of used Ni catalyst was achieved by oxidation-reduction steps at 723 K.
Srinivasan, S.; Fernandez, M.; Ramon, E.; Garriga, P. Biochimica et Biophysica Acta - Molecular Basis of Disease Vol. 1863, p. 1-8 DOI: 10.1016/j.bbadis.2017.05.006 Data de publicació: 2017-07-01 Article en revista
Deuteranopia is an X-linked congenital dichromatic condition in which single point mutations in green cone opsin lead to defective non-functional cone photoreceptor cells. Green cone opsin belongs to the G protein-coupled receptor superfamily and consists of a seven transmembrane helical apoprotein covalently bound to 11-cis-retinal, by means of a protonated Schiff base linkage, in its inactive dark state. Several point mutations in green cone opsin have been reported to cause deuteranopia, but the structural details underlying the molecular mechanisms behind the malfunction of mutated opsins have not been clearly established. Here, deutan N94K and R330Q mutants were studied by introducing these substitutions into the native green cone opsin gene by site-directed mutagenesis. The mutant proteins were purified and analyzed using UV-vis spectroscopy and transducin activation assay. We find that the N94K mutant binds the retinal chromophore by means of an unprotonated Schiff base linkage in contrast to previous studies that reported no chromophore regeneration. The other mutant studied, R330Q, showed impaired functionality as measured by its reduced transducin activation ability when compared to wild-type green cone opsin. A double Cys mutant that could form a stabilizing disulfide bond was used in an attempt to address the instability of the green opsin mutants. Our results suggest the presence of key intramolecular networks which may be disrupted in deuteranopia, and these findings could help in finding therapeutic solutions for treating color blindness. Furthermore, our results can also have implications for the study of other visual pigments and other rhodopsin-like G protein-coupled receptors.
González, N.; Custal, M.A.; Rodríguez, D.; Riba, J.; Armelin, E. Materials research-Ibero-american journal of materials Vol. 20, num. 4, p. 1-10 DOI: 10.1590/1980-5373-MR-2017-0178 Data de publicació: 2017-07-01 Article en revista
The novelty of the present study relies on the straightforward sonication of ZnO and TiO2 and incorporation to a complex formulation of latex, with other several organic-inorganic additives that influences the cross-linking reactions. The new elastomer with particles carefully sonicated exhibit improved electrical and mechanical properties. Strong interaction among the nanoparticles and the polymer amorphous phase has been proved by means of FTIR, SEM and XRD analyses. The synergistic effect of hybrid fillers with nanometric dimensions can be used to design high-performance natural rubber nanocomposites with enhanced electrical resistance and good cross-linking degree.
Engineering the shape and size of catalyst particles and the interface between different components of heterogeneous catalysts at the nanometer level can radically alter their performances. This is particularly true with CeO2-based catalysts, where the precise control of surface atomic arrangements can modify the reactivity of Ce4+/Ce3+ ions, changing the oxygen release/uptake characteristics of ceria, which, in turn, strongly affects catalytic performance in several reactions like CO, soot, and VOC oxidation, WGS, hydrogenation, acid–base reactions, and so on. Despite the fact that many of these catalysts are polycrystalline with rather ill-defined morphologies, experimental and theoretical studies on well-defined nanocrystals have clearly established that the exposure of specific facets can increase/decrease surface oxygen reactivity and metal–support interaction (for supported metal nanoparticles), consequently affecting catalytic reactions. Here, we want to address the most recent developments in this area, showing that shape (and size) modification, surface/face reconstruction, and faceting of ceria at the nanoscale level can offer an important tool to govern activity and stability in several reactions and imagine how this could contribute to future developments.