Cyclic oligo(butylene 2,5-furandicarboxylate) and e-caprolactone were copolymerized in bulk at 130-150 °C by enzymatic ring opening polymerization using CALB as catalyst. Copolyesters within a wide range of compositions were thus synthesized with weight-average molecular weights between 20,000 and 50,000, the highest values being obtained for equimolar or nearly equimolar contents in the two components. The copolyesters consisted of a blocky distribution of the e-oxycaproate (CL) and butylene furanoate (BF) units that could be further randomized by heating treatment. The thermal stability of these copolyesters was comparable to those of the parent homopolyesters (PBF and PCL), and they all showed crystallinity in more or less degree depending on composition. Their melting and glass-transition temperatures were ranging between those of PBF and PCL with values increasing almost linearly with the content in BF units. The ability of these copolyesters for crystallizing from the melt was evaluated by comparative isothermal crystallization and found to be favored by the presence of flexible e-oxycaproate blocks. These copolyesters are essentially insensitive to hydrolysis in neutral aqueous medium but they became noticeably degraded by lipases in an extend that increased with the content in CL units.
Safarpoor, M.; Ghaedi, M.; Asfaram, A.; Yousefi, M.; Javadian, H.; Zare, H. Ultrasonics sonochemistry Vol. 42, p. 76-83 DOI: 10.1016/j.ultsonch.2017.11.001 Data de publicació: 2018-04-01 Article en revista
Hosseini Asl, S.; Ghadi, A.; Sharifzadeh Baei, M.; Javadian, H.; Maghsudi, M.; Kazemian, H. Fuel (Guildford) Vol. 217, p. 320-342 DOI: 10.1016/j.fuel.2017.12.111 Data de publicació: 2018-04-01 Article en revista
Chronic wounds represent a challenge to wound care professionals consuming a great deal of healthcare resources and, at the same time, reducing patient life quality with increased hospitalization times, heavy pain and eventually sepsis and death. Heavy bacterial colonisation is the main reason for non-healing chronic wounds, consequently wounds are often treated with antibiotics prophylactically, thus leading to unnecessary selection for bacterial resistance. Hence, there is a need for point of care testing (PoCT) devices for the evaluation of infection biomarkers allowing an early and appropriate treatment to reduce the severity of the disease and avoid the chronicity. In the last decade, paper based PoCT devices has showed great potential with the development of cheap and versatile microfluidic and lateral flow devices. These devices incorporate sensing molecules (e.g. enzyme substrates) immobilized in specific spots within the paper platform where they will react with determined biomarkers when the liquid sample flows through the device. Myeloperoxidase (MPO) an enzyme secreted by neutrophils and detected in fluids of infected wounds has been postulated as a suitable biomarker for wound diagnostics. MPO catalyzes the oxidation of chloride ions to hypochlorous acid (HClO), a powerful bactericidal oxidant, using hydrogen peroxide as co-substrate. At the same time, MPO can oxidize a variety of molecules including phenols, quinones, hydrazines and also proteins. Taking advantage of MPO substrate promiscuity, here we present an unexplored system for MPO detection based on enzyme-catalysed oxidative dye polymerization which can be incorporated into paper-based PoCT devices. Visual MPO detection has been achieved through the use of phenylenediamines, a common dye component, which its oxidation byMPO yielded bright coloured products distinguishable from the colour of the wound environment. Using paper strips as model of paper-based lateral flow device, immobilisation of the dye substrate was achieved through in situ interaction of the oxidised coloured product with a polycationic polymer. The colour reaction of the immobilised substrates, detectable by naked eye, responds to the MPO levels present in infected wound fluids. Thus revealing an easy system for incorporation of MPO detection in paper based diagnostic devices.
Bacteria-mediated diseases are a global healthcare concern due to the development and spread of antibiotic resistant strains. Cationic compounds are considered membrane active biocidal agents having a great potential to control bacterial infections, while limiting the emergence of drug resistance. Herein, the versatile and simple Layer-by-Layer (LbL) technique was used to coat alternating multilayers of an antibacterial aminocellulose conjugate and the biocompatible hyaluronic acid on biocompatible polymer nanoparticles (NPs), taking advantage of the nano-size of these otherwise biologically inert templates. Stable polyelectrolyte-decorated particles with an average size of 50 nm and zeta potential of + 40.6 mV were developed after five LbL assembly cycles. The antibacterial activity of these NPs against the Gram-positive Staphylococcus aureus and Gram- negative Escherichia coli increased significantly when the polycationic aminocellulose was in the outermost layer. The large number of amino groups available on the particles surface, together with the nano-size of the multilayer conjugates, improved their interaction with bacterial membrane phospholipids leading to membrane disruption, as confirmed by a Langmuir monolayer model, and the 10 logs bacterial reduction. The biopolymer decorated NPs were also able to inhibit the biofilm formation of Staphylococcus aureus and Escherichia coli by 99 and 40 %, respectively, without affecting human cells viability. The use of LbL coated NPs appears as a promising antibiotic-free alternative for controlling bacterial infections using low amount of antimicrobial agent.
Silver nanoparticles (Ag-NPs) have been among the most commonly used nano-materials in our health care system, widely used in a range of biomedical applications, including diagnosis, treatment, drug delivery, medical device coating and for personal health care. Ag-NPs present unique physicochemical properties such as antibacterial, antifungal, antiviral and anti-inflammatory activity. In this matter, bionanocomposites materials, formed by the combination of natural polymers and inorganic components, like hybrid Ag-NPs, represents an important stake in scientific research offering the combined properties inherent to the natural biopolymers and inorganic nanoparticles. Meanwhile, hyaluronic acid (HA), an immunoneutral polysaccharide ubiquitously present in the human body, is an attractive starting materials since can be chemically modified through its reactive functional groups and transformed into many physical forms (viscoelastic solutions, soft or stiff hydrogels or even nanoparticulate fluids) as a biocompatible platform for a wide range of biomedical applications.
Multifunctional hydrogels were enzymatically generated by the crosslinking reaction between silver lignin nanoparticles (Ag-Lig NPs) and thiolated hyaluronic acid (HA-SH). First, Ag-lig NPs were synthesized using a green, eco-friendly procedure from aqueous AgNO3 solution with lignin, one of the most abundant biopolymers in nature, serving as a dual reducing and capping agent. Afterwards, the multiple functional groups present in lignin, mainly phenolic hydroxyls, serve as reactive groups to crosslink with thiol groups from HA by the action of the enzyme laccase. The morphology, swelling properties, and rheological characteristics of the performed HA hydrogels with embedded Ag-lig NPs together with their stability, control over MMP and MPO and cellularROS scavenging were investigated. Finally, the potential toxicology, the silver release from the hydrogel matrix, the anti-inflammatory effect and the antibacterial activity in front of different bacterial stains were addressed to explore their potential biomedical applications.
An important preventive measure to avoid nosocomial infections is introducing highly efficient and durable antibacterial textiles and medical devices, e.g. catheters, into the hospital. Coatings of metal oxide (MeO) nanoparticles (NPs), such as ZnO, would ensure excellent antimicrobial properties of these products at minor cytotoxicity. Ultrasound (US) is an easy, fast and environmentally friendly surface nano-coating technology able to synthesize and deposit in a single step antimicrobial NPs on material’s surface.
We applied hydrolytic enzymes, i.e. cellulases, to coat cotton fabrics with ZnO NPs via US irradiation either in a two-step process for cellulose pre-activation, followed by sonochemical deposition of ZnO NPs, or in a one- step sono-enzymatic process to simultaneously activate cellulose and deposit ZnO NPs achieving high durability of the antimicrobial effect.
Further, we developed durable and efficient antibacterial coatings on medical textiles by depositing antibacterial ZnO NPs and gallic acid (GA) in a single-step laccase/US process. The rationale behind this sono-enzymatic approach was the in situ synthesis, upon the enzymatic oxidation of GA, of a bio-adhesive, in which the ZnO NPs are firmly embedded on the fabric surface. Additionally, a synergistic improvement of the antibacterial efficiency of lower amount ZnO NPs by the natural antimicrobial agent GA was achieved.
We also used US for coating of silicone catheters with hybrid enzyme/ZnO NPs. The antibacterial and anti- biofilm efficiency of the coated fabrics and catheters were validated against major clinically relevant bacterial pathogens. The sonochemical NP-coating technology was scaled-up into pilots that currently are being upgraded under the EU-FP7 project PROTECT into pre-commercial coating lines installed at Klopman Int. (Italy) and Degania Silicone (Israel) for production of antimicrobial textiles, water treatment membranes and catheters.
The emergence of drug-resistance microbial pathogens is creating a worldwide healthcare problem. Nanoparticles have been increasingly used as alternative to the antibiotics. Antimicrobial nanoparticles offers a platform against bacteria, viruses, fungus and protozoa and perform this activity by destroying cell membranes, blocking enzyme pathways, altering microbial cell wall, metabolic pathways and protein, DNA expression and acting on components from the extracellular matrix of biofilms. The advantages of the antimicrobial nanoparticles reside in their different mechanisms of action against pathogens, e.g. oxidative stress, metal ion release, or non-oxidative mechanism, which can occur simultaneously. These mechanisms are less likely to cause the appearance of microbial resistance.
Bacterial biofilms are structured, coordinated communities with distinct architectures and properties. They are ubiquitous in nature and possess the sophisticated ability to rapidly adapt and propagate in a wide variety of habitats. Microbial biofilms are at the root of many chronic and recurrent infections and their formation have been estimated to account for 80 % of all microbial infections currently treated in hospitals. Biofilm can grow on any foreign object inserted into the human body but also in different surfaces of the hospital premises.
In this study, we synthesized hybrid enzyme-metal nanoparticles combining the synergistic activities of different antimicrobial agents. The enzyme in the hybrid nano-entities acts on the extracellular components secreted by the bacterial populations to eliminate and to inhibit the formation of biofilm. On the other hand, the biocidal properties of the nanoparticle are provided by the metal counterpart in the naoparticulate composite. This antimicrobial approach could be applied in the form of coatings on surfaces such as hospital textiles, water treatment membranes and implantable medical devices, ensuring a safer environment for both patients and healthy population.
The occurrence of drug resistance is global healthcare concern, and although new drugs are constantly being sought, the pace of development is slow compared to the evolution and spread of multidrug resistant bacteria. The high persistence of bacteria in the form of both planktonic cells and biofilms on living tissues and medical surfaces calls for novel antibacterial strategies for the prevention and treatment of bacterial infections. In this study, enzymatic disruption of bacterial quorum sensing by acylase and ultrasound assisted nanospherization were innovatively combined to enhance the bactericidal e ffi cacy of the conventional antibiotic gentamicin, lowering the drug dosage. The generated hybrid nanoantibacterials were stable, with zeta potential – 40 ± 0.23 mV and size of 200 ± 1nm. They possessed membrane disrupting capacity and killed the medically relevant Gram-negative Pseudomonas aeruginosa bacteria after 45 min. The synergistic combination demonstrated improved antibiofilm activity compared to the individual counterparts and reduced the resistant P. aeruginosa biofilm up to 6 logs. Moreover, the bactericidal e ffi caicy of the hybrids was not drastically a ff ected in “protein corona” conditions, demonstrating their real application scenario. Further in situ ultrasound assisted synthesis and deposition of the acylase enzyme and gentamicin onto the surface of urinary catheters increased the life span of the medical devices and decreased the occurrence of bacterial biofilms. The obtained hybrid nanoantibacterials with complimentary modes of action were not found innocuous towards human fibroblasts (BJ-5ta cells) and as a such might be valuable alternative to control bacterial diseases at reduced antibiotic dosages.
Osteoarthritis (OA) is a degenerative disease characterised with pain, stiffness and loss of function in the weight-bearing joints, caused by the inflammatory biological molecules that disturb the balance between the tissue synthesis and degradation. Maintaining the composition of the physiological lubricant, named synovial fluid, by restoration of homeostasis is thus a necessary step to retard the OA progression and provide a suitable environment for tissue remodelling.
Thiolated hyaluronic acid (HA-SH) was enzymatically crosslinked with gallic acid (GA) by the action of laccase as a method to prepare multifunctional hydrogels, designed as delivery systems that enable long-term efficiency of biological entities in cell-based therapies. Owing to its characteristics and mild conditions employed, the encapsulation of very unstable and sensitive cargoes is possible, highlighting its potential as a platform for a variety of biomedical applications. A cytokine cocktail (ACC) and chondrocytes cells were encapsulated together as therapy to delay the disease progression and boost the anabolic pathways for recovery of the damaged cartilage. The morphology, swelling ratio, rheological properties and stability of the hydrogels were characterised and optimised in order to fit the requirements of the therapy. The efficiency of the developed platforms was evaluated in vitro against the major factors governing the OA disease, namely the anti-inflammatory effect, cellular ROS scavenging and the inhibitory capacity of the hydrogels towardsdeleterious enzymes as MMPs, MPO and hyalurodinase. Finally, experiments to determine the ability of the cells to survive, growth and differentiate in the multifunctional hydrogels were assessed in order to explore their potential in a cell-based therapies and regenerative medicine.
Fernandez de Labastida, M.; Licon, E.; Bondarenko, M.; Yaroshchuk, A. Journal of membrane science num. 550, p. 492-501 DOI: 10.1016/j.memsci.2017.10.057 Data de publicació: 2018-03-15 Article en revista
This work presents a new approach to correcting for concentration polarization (CP) in pressure-driven membrane measurements. In the existing test cells (both cross-flow and stirred-batch) there are distributions of extent of CP over membrane surface. This complicates the interpretation of experimental data.A novel design of test cell with equally-accessible membrane surface has been developed based on the classical configuration of rotating disk combined with the possibility of applying trans-membrane hydrostatic pressure differences of up to 20. bar. Due to the equal accessibility, corrections for CP can easily be made even in multi-ionic systems, which would be much more difficult with other membrane test cells.Since the membrane has to be sealed at the edge the geometry somewhat deviates from the ideal case of infinite disk. The impact of these deviations has been quantified via CFD simulations. A major part of the membrane surface is shown to be equally accessible while there are some expectable deviations close to the sealed membrane edge. This zone could be “screened“ in the experiments. The approach could also be validated experimentally via studying the dependence of observed rejection on the rotation speed and demonstrating that intrinsic rejection was practically independent of it.Finally, to demonstrate the cell utility, we performed and interpreted a number of experiments using commercial NF270 membrane and various feed solutions (single salts and electrolyte mixtures). We conclude that this cell can be employed for systematic transport characterization of membranes and the obtained information can be used as input in the CFD modelling of membrane modules.
Carrillo, F.; Casadesus, M.; Macanás, J.; Colom, X.; Cañavate, J.; M.D. Alvarez; Garrido, N.; Molins, G. AATCC International Conference p. 1-2 Data de presentació: 2018-03-07 Presentació treball a congrés
Sorolla, S.; Flores, A.; Canals, T.; Cantero, M.R.; Font Vallès, Joaquim; Olle, L.; Bacardit, A. Journal of the American Leather Chemists Association Vol. 113, num. 3, p. 88-93 Data de publicació: 2018-03-05 Article en revista
The main aim of this study is to carry out a qualitative and semiquantitative analysis of tannin extracts as an alternative to the official analysis method ISO 14088 – IUC 32, so that a correlation between the two methods is established.
From the point of view of the chemical composition, tannins are classified into two major groups: i) condensed tannins, also called flavanols or catechins, and ii) hydrolysable tannins, also called pyrogallic tannins.
Today, the most widely used conventional extracts are quebracho, mimosa, chestnut, and tara. Quebracho and mimosa are condensed tannins, whereas chestnut and tara are hydrolysable tannins.
The following extracts were used in this study: tara powder, commercial mimosa and quebracho extracts and extracts derived from grape seed, containing both condensed and hydrolysable extracts.
The development of this new method will allow a faster and less expensive estimate of the amount of tannins present in a tannin extract.
Lopes, M.; Triguero, J.; Torras, J.; Perpète, Eric A.; Michaux, Catherine Anne Gisèle; Aleman, C.; Zanuy, D. Biophysical chemistry Vol. 234, p. 6 DOI: 10.1016/j.bpc.2017.12.003 Data de publicació: 2018-03-01 Article en revista
En estos últimos años, como consecuencia del cambio climático, ha aumentado extraordinariamente el interés por materiales sostenibles. El reemplazo de los compuestos de origen petroquímico por naturales se ha extendido a todos los ámbitos de la química. Se están desarrollando polímeros sostenibles basados en ácido 2.5-furandicarboxílico (FDCA) ya que pueden competir en prestaciones con los basados en el ácido tereftálico (PTA). Por otro lado, la polimerización entrópica por apertura de anillo (ED-ROP) es una vía de síntesis atractiva cuyo interés ha crecido en esta última década debido a que la reacción es atérmica, no se generan subproductos y se puede obtener polímeros de alto peso molecular en cortos tiempos de reacción.En esta Tesis se reporta la síntesis y caracterización de oligómeros cíclicos de FDCA con diferentes dioles, tales como 1,4- butanodiol (c(BF)n), etilenglicol (c(EF)n), resorcinol (c(RF)n) e isomannide (c(ImF)n) usando diferentes rutas sintéticas incluyendo la condensación con alta dilución (HDC), la ciclodepolimerización (CD). También se han sintetizado mediante HDC los oligómeros cíclicos de butilén isoftalato (c(BI)n) y butilén tereftalato (c(BT)n). Finalmente, se han obtenido los oligómeros cíclicos de butilén succinato (c(BS)n) y etilén succinato (c(ES)n) por reacción de ciclación enzimática (EC).Los oligómeros cíclicos furánicos se homopolimerizaron y copolimerizaron con los oligoesteres cíclicos mencionados anteriormente así como con la epsilon-caprolactona (e-CL). Las reacciones de polimerización fueron catalizadas con el octanoato de estaño (SnOct2), excepto en el caso de los homopoliésteres y copoliésteres con unidades alifáticas en los que se utilizó la enzima lipasa B de Cándida antárctica (CALB). Los pesos moleculares de los polímeros obtenidos oscilaron entre 25,000 y 80,000 g/mol. Los copolímeros presentaban una microestructura al azar con la excepción de los derivados de caprolactona, los cuales presentaron una microestructura en bloques.Los estudios de calorimetría diferencial de barrido (DSC) revelaron que el PEF, PBF, PBT, PBI, PBS, PES, y sus copolímeros con menos del 30% de comonómero alifático, resultaron ser cristalinos, por el contrario, los copolímeros con composiciones cercanas al 50:50 resultaron ser por lo general amorfos. Por otro lado, el PRF y el PImF eran amorfos y la incorporación de sus unidades en otros copoliésteres restringió la cristalinidad de los mismos. Además la temperatura de fusión (Tm) y la temperatura de transición vítrea (Tg) eran intermedias a las de los homopoliésteres, con una tendencia prácticamente lineal en el segundo caso. También se estudió la cristalizabilidad de la mayoría de los copoliésteres, lo cual permitió la obtención de diferentes parámetros cinéticos mediante la aplicación de la ecuación de Avrami.El análisis termogravimétrico (TGA) reveló que la mayoría de los poliésteres y copoliésteres eran térmicamente estables hasta 400 oC.Los estudios de degradabilidad hidrolítica y enzimática mostraron la alta resistencia a la degradación del PBF, PEF y PRF, la cual decrecía notablemente con la incorporación de unidades alifáticas tales como el BS, ES, CL o ImF.La presente Tesis resume los principales aspectos en la síntesis de oligómeros cíclicos de FDCA y su homopolimerización y copolimerización con diferentes oligómeros cíclicos vía ED-ROP. De acuerdo con los resultados obtenidos, los poliésteres basados en derivados furánicos podrían considerarse como una alternativa viable a los poliésteres de origen químico.
Sustainability issues, as unwanted results of not fully respecting natural cycles, are widely recognized as wicked problems, which should not be thought of as problems to be solved, but rather as “conditions” to be managed, as if they were a chronic disease (Seager et al., 2011).
There exists a general agreement on the need to reform scientific expertise by developing new ways of knowledge production and decision-making able to cope with the challenges sustainability poses. In this sense, transdisciplinary aspects of sustainability are acknowledged as a transformational stream of sustainability science
The industrial process of nitrogen fixation is complex and results in a huge economic and environmental impact. It requires a catalyst and high temperature and pressure to induce the rupture of the strong N–N bond and subsequent hydrogenation. On the other hand, carbon dioxide removal from the atmosphere has become a priority objective due to the high amount of global carbon dioxide emissions (i.e. 36 200 million tons in 2015). In this work, we fix nitrogen from N2 and carbon from CO2 and CH4 to obtain both glycine and alanine (D/L racemic mixture), the two simplest amino acids. The synthesis, catalyzed by polarized hydroxyapatite under UV light irradiation and conducted in an inert reaction chamber, starts from a simple gas mixture containing N2, CO2, CH4 and H2O and uses mild reaction conditions. At atmospheric pressure and 95 °C, the glycine and alanine molar yields with respect to CH4 or CO2 are about 1.9% and 1.6%, respectively, but they grow to 3.4% and 2.4%, when the pressure increases to 6 bar and the temperature is maintained at 95 °C. Besides, the minimum temperature required for the successful production of detectable amounts of amino acids is 75 °C. Accordingly, an artificial photosynthetic process has been developed by using an electrophotocatalyst based on hydroxyapatite thermally and electrically stimulated and coated with zirconyl chloride and a phosphonate. The synthesis of amino acids by direct fixation of nitrogen and carbon from gas mixtures opens new avenues regarding the nitrogen fixation for industrial purposes and the recycling of carbon dioxide.
The conventional unhairing process is one of the most pollutant steps in the leather tanning process,
which usually involves great amounts of sulphides, lime and soda ash, generating high BOD and COD
values in the wastewater.
In this work, we have investigated different oxidative agents, combined or not with enzymes, as a
possible replacement for sulphides in unhairing, focused on the possible industrial application of the
method developed. Peroxymonocarbonate anion, persulfate anions (peroxymonosulfate and
peroxydisulfate anion) and peroxynitrite anion have been chosen and the dehairing of bovine leather
has been performed. The performance has been compared in terms of dehairing ability, time,
suspended solids, pH, conductivity, COD and total nitrogen (Kjeldahl). All the tests were compared with
a pilot test (hair-saving sulphide unhairing) and with a hydrogen peroxide dehairing. The results show
the great ability of percarbonate, combined with enzymes, to give complete unhairing in 16 hours, no
grain damage in absence of sulphides, and great homogeneity after dyeing tests. The results, also,
showed a greater reduction of pollutants in the wastewater.
Bahrani, S.; Ghaedi, M.; Ostovan, A.; Javadian, H.; Khoshnood Mansoorkhani, M.; Taghipour, T. Journal of pharmaceutical and biomedical analysis Vol. 149, p. 166-171 DOI: 10.1016/j.jpba.2017.10.040 Data de publicació: 2018-02-05 Article en revista
In this research, a facile and selective method was described to extract L-cysteine (L-Cys), an essential a-amino acid for anti-ageing playing an important role in human health, from human blood plasma sample. The importance of this research was the mild and time-consuming synthesis of zinc organic polymer (Zn-MOP) as an adsorbent and evaluation of its ability for efficient enrichment of L-Cys by ultrasound-assisted dispersive micro solid-phase extraction (UA-DMSPE) method. The structure of Zn-MOP was investigated by FT-IR, XRD and SEM. Analysis of variance (ANOVA) was applied for the experimental data to reach the best optimum conditions. The quantification of L-Cys was carried out by high performance liquid chromatography with UV detection set at ¿ = 230 nm. The calibration graph showed reasonable linear responses towards L-Cys concentrations in the range of 4.0–1000 µg/L (r2 = 0.999) with low limit of detection (0.76 µg/L, S/N = 3) and RSD = 2.18 (n = 3). The results revealed the applicability and high performance of this novel strategy in detecting trace L-Cys by Zn-MOP in complicated matrices.
Fires can be an important hazard for the safety of chemical and process industries. Particularly, pool fires are the most frequent fire scenarios in such facilities and can affect other equipment of the plant with severe consequences due to the domino effect. During the last decades, simplified fire modelling tools were used to predict some of the harmful effects that hydrocarbon pool fires may entail. Although these can be applied to limited number of scenarios, they cannot cover the overall characteristics governing the fire behaviour. Computational Fluid Dynamics (CFD) modelling may provide more detailed insights of the related fire effects, may consider complex geometries and may represent from small to large-scale fires. However, simulation results should be firstly compared to experimental measurements in order to assess the predictive capabilities of these tools.
This paper investigates the predictive capabilities of CFD modelling when performing a priori simulations of large-scale hydrocarbon pool fires. The main objective is to assess the fire effects prediction performance of two CFD codes that may be used to evaluate the hazard of hydrocarbon pool fires. FLACS-Fire and FDS codes have been used to simulate large-scale pool fires (1.5, 3, 4, 5 and 6 m-diameter) of diesel and gasoline fuels in unconfined environments. Given the notable differences between the mathematical methods applied to solve the CFD sub-models, the mesh resolution and the boundary conditions in each investigated tool, this study is not aimed at directly comparing both codes (i.e. using identical sub-models choices). However, the present CFD analysis is intended to reveal the potential of each software separately by applying the most appropriate modelling options for each tool. Based on a qualitative assessment of the predictions and a quantitative error estimation of the variables measured (i.e. flame temperature, burning rate, heat flux, flame height, flame surface, and surface emissive power), the main strengths and weaknesses of FLACS-Fire and FDS are identified when modelling hydrocarbon pool fires.
The physical aging behaviour of two epoxy-thiol shape memory polymers has been studied: diglycidyl ether of bisphenol-A cross-linked with pentaerythritol tetrakis, denoted 4-thiol, with a calorimetric glass transition temperature, Tg, of 51 °C; and the same system modified with tri (2,3-epoxypropyl)isocyanurate in a 30 wt% proportion, denoted 4-thiol-30%iso, with Tg = 63 °C. The aging of both polymers has been measured by torsional creep for aging temperatures between room temperature and the Tg of each polymer. The creep behaviour of each polymer is characterised by a discrete distribution of relaxation times, which shifts with aging time according to a double logarithmic aging rate, µ, and with aging temperature according to an activation energy. The distribution of creep relaxation times for 4-thiol is rather symmetrical, and slightly narrower than that for 4-thiol-30%iso, which is also skewed to longer times. The dependence of µ on temperature displays a peak as the aging temperature reduces below Tg, and is sharper for 4-thiol, in accordance with the narrower distribution, as predicted by a theoretical model based upon structural relaxation kinetics. The other parameters defining the aging behaviour, namely the reduced activation energy (¿h*/R = 92 kK for 4-thiol and 82 kK for 4-thiol-30%iso) and the non-linearity parameter of structural relaxation (x = 0.35 for 4-thiol and 0.25 for 4-thiol-30%iso), have been determined experimentally and are compared with the predictions of the theoretical model. These parameters can be used to predict the effects of physical aging on the shape memory response.
The contact of the coolant with the fuel pin during irradiation produces a gradient of temperature in the fuel pellet that segregates the radionuclides (RN) depending on its volatility and reactivity. This segregation determines the Instant Release Fraction (IRF), an important source of radiological risk in the performance assessment (PA) of a Deep Geologic Repository (DGR). RN segregation was studied radially in previous papers. In the present work, it was studied axially, taking into special consideration the cutting position of the solid sample to be studied. Iodine and caesium were the RN with the highest release, while the contribution of rubidium, strontium, molybdenum and technetium to the IRF depended on their chemical state. The interpellet presence (known also as dishing) effect was clearly observed for caesium, increasing its release by one order of magnitude. According to these results, one of the major contributions to the IRF comes from the RN trapped in the dishing and has to be considered in the sampling and data interpretation that will be performed for the PA of the DGR.
Morales, J.; Martinez de Ilarduya, A.; Muñoz, S. Journal of polymer science. Part A, polymer chemistry Vol. 56, num. 3, p. 290-299 DOI: 10.1002/pola.28895 Data de publicació: 2018-02-01 Article en revista
Cyclic oligo(butylene 2,5-furandicarboxylate) and e-caprolactone were copolymerized in bulk at 130-150 ºC by enzymatic ring opening polymerization using CALB as catalyst. Copolyesters within a wide range of compositions were thus synthesized with weight-average molecular weights between 20,000 and 50,000, the highest values being obtained for equimolar or nearly equimolar contents in the two components. The copolyesters consisted of a blocky distribution of the e-oxycaproate (CL) and butylene furanoate (BF) units that could be further randomized by heating treatment. The thermal stability of these copolyesters was comparable to those of the parent homopolyesters (PBF and PCL), and they all showed crystallinity in more or less degree depending on composition. Their melting and glass-transition temperatures were ranging between those of PBF and PCL with values increasing almost linearly with the content in BF units. The ability of these copolyesters for crystallizing from the melt was evaluated by comparative isothermal crystallization and found to be favored by the presence of flexible e-oxycaproate blocks. These copolyesters are essentially insensitive to hydrolysis in neutral aqueous medium but they became noticeably
QM/MM molecular dynamics simulations on the 4His-DC* protein cage have been performed using multiple active zones (up to 86 quantum regions). The regulation and nanocage stability exerted by the divalent transitionmetal ions in the monomer-to-cage conversion have been understood by comparing high level quantum trajectories obtained using Cu2+ and Ni2+ coordination ions.
Drug resistance occurrence is a global healthcare concern responsible for the increased morbidity and mortality in hospitals, time of hospitalisation and huge financial loss. The failure of the most antibiotics to kill Bsuperbugs^ poses the urgent need to develop innovative strategies aimed at not only controlling bacterial infection but also the spread of resistance. The prevention of pathogen host invasion by inhibiting bacterial virulence and biofilm formation, and the utilisation of bactericidal agents with different mode of action than classic antibiotics are the two most promising new alternative strategies to overcome antibiotic resistance. Based on these novel approaches, researchers are developing different advanced materials (nanoparticles, hydrogels and surface coatings) with novel antimicrobial properties. In this review, we summarise the recent advances in terms of engineered materials to prevent bacteria-resistant infections according to the antimicrobial strategies underlying their design.
The established action potential propagation mechanisms do not satisfactorily explain propagation on myelinated axons given the current knowledge of biological channels and membranes. The flow across ion channels presents two possible effects: the electric potential variations across the lipid bilayers (action potential) and the propagation of an electric field through the membrane inner part. The proposed mechanism is based on intra-membrane electric field propagation, this propagation can explain the action potential saltatory propagation and its constant delay independent of distance between Ranvier nodes in myelinated axons.
Guaya, D.; Valderrama, C.; Farran, A.; Sauras, T.; Cortina, J. Science of the total environment Vol. 612, p. 728-738 DOI: 10.1016/j.scitotenv.2017.08.248 Data de publicació: 2018-01-15 Article en revista
The removal of nutrients (nitrogen (N), phosphorous (P)) from waste water has become a resource recovery option in recent regulations worldwide, as observed in the European Union. Although both of these nutrients could be recovered from the sludge line, > 70–75% of the N and P is discharged into the water line. Efforts to improve the nutrient recovery ratios have focused on developing low-cost technologies that use sorption processes. In this study, a natural zeolite (clinoptilolite type) in its potassium (K) form was impregnated with hydrated metal oxides and used to prepare natural hybrid reactive sorbents (HRS) for the simultaneous recovery of ammonium (NH4 +) and phosphate (PO4 3 -) from treated urban waste water. Three unfertile soils (e.g., one acidic and two basic) amended with N-P-K charged HRS were leached with deionized water (e.g. to simulate infiltration in the field) at two- and three-day time intervals over 15 different leaching cycles (equivalent to 15 bed volumes). The N-P-K leaching profiles for the three charged hybrid sorbents exhibited continuous nutrient release, with their values dependent on the composition of minerals in the soils. In the basic soil that is rich in illite and calcite, the release of potassium (K+) and ammonium (NH4 +) is favoured by-ion exchange with calcium (Ca2 +) and accordingly diminishes the release of phosphate (PO4 3 -) due to its limited solubility in saturated calcite solutions (pH 8 to 9). The opposite is true for sandy soils that are rich in albite (both acidic and basic), whereas the release of NH4 + and K+ was limited and the values of both ions measured in the leaching solutions were below 1 mg/L. Their leaching solutions were poor in Ca2 +, and the release of PO4 3 - was higher (up to 12 mg P-PO4 3 -/L). The nutrient releases necessary for plant growth were provided continuously and were controlled primarily by the soil mineral dissolution rates fixing the soil aqueous solution composition (e.g. pH and ionic composition; in particular, the presence of calcite is a determinant for nutrient release, especially in alkaline soils). The N-P-K charged HRS sorbents that were used for soil amendment may be an alternative for avoiding nutrient leaching and reaching the goals of soil sustainability in agriculture and reducing the nutrient overloading of surface waters.
Phosphorus (P) is a vital macronutrient required to improve the agricultural yields but its excessive use as a fertilizer has resulted in pollution of water bodies leading to eutrophication. With no reserves of phosphorus source in Spain, increased dependence on phosphorus in agriculture have not only increased dependence on imports but also has raised concerns on its future availability as a resource. A Phosphorous Flow Analysis (PFA) was conducted for Spain for the year 2012 focusing on the food production and consumption systems. The results obtained were finally compared with PFA at both country level and continent level (EU-27). To quantify food and non-food flows systems, country specific data were considered. The sectors covered were crop production (CP), animal production (AP), food processing (FP), non-food production (NF) and consumption (HC). The findings reveal that a total of 325 kt P was imported by Spain in 2012; 66% of which was accumulated in markets stock of food and feed, fertilizers and non-food (91 kt P) while 33% was lost to the environment through land-fill, losses to water bodies, land accumulation and incineration. The largest proportion of losses is associated with water bodies (44.7 kt P) followed by agriculture and land accumulation (42.1 kt P). Wastewater treatment plants (WWTPs) received around 79.5 kt P within wastewater, with 60% being removed in sewage sludge. The 31.7 kt P discharged within final effluent represented the 71% of the total losses to water bodies. Around 69% of the sewage sludge was recycled to agriculture and 27% was sent directly to landfill including the ashes from incineration. Net accumulation was 1.84 kg P/cap which was similar to values reported for the EU-27 average (2.5 kg P/cap).
acteria-mediated diseases are a global healthcare concern due to the development and spread of antibiotic resistant strains. Cationic compounds are considered membrane active biocidal agents having a great potential to control bacterial infections, while limiting the emergence of drug resistance. Herein, the versatile and simple Layer-by-Layer (LbL) technique was used to coat alternating multilayers of an antibacterial aminocellulose conjugate and the biocompatible hyaluronic acid on biocompatible polymer nanoparticles (NPs), taking advantage of the nano-size of these otherwise biologically inert templates. Stable polyelectrolyte-decorated particles with an average size of 50 nm and zeta potential of + 40.6 mV were developed after five LbL assembly cycles. The antibacterial activity of these NPs against the Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) increased significantly when the polycationic aminocellulose was in the outermost layer. The large number of amino groups available on the particles surface, together with the nano-size of the multilayer conjugates, improved their interaction with bacterial membrane phospholipids leading to membrane disruption, as confirmed by a Langmuir monolayer model, and the 10 logs reduction for both bacteria. The biopolymer decorated NPs were also able to inhibit the biofilm formation of S. aureus and E. coli by 94 and 40%, respectively, without affecting human cells viability. The use of LbL coated NPs appears as a promising antibiotic-free alternative for controlling bacterial infections using low amount of antimicrobial agent.
The solvent extraction of germanium and some heavy metals by commercial tri-octyl/decyl amine (Alamine 336), N-methyl-N, N-dioctyl chloride (Aliquat 336) and phosphine oxide (Cyanex 923) has been studied. In each extraction system, germanium was only extracted from a solution containing nickel, cadmium, cobalt, and zinc, which had a composition similar to gasification coal fly ash aqueous leach solutions. Under a comparable condition, the germanium extraction efficiency by the aforementioned extractants was in the order Aliquat 336 > Alamine 336 > Cyanex 923. The slope analysis method showed that 2 moles of Alamine 336 and Aliquat 336, as well as 4 moles of Cyanex 923, participated in the extraction of germanium. In amine extraction systems, tartaric acid was required as a complexant used to convert germanium to anionic species. As a result, the ratio of 2 (mole ration of tartaric acid to Ge) was required to complete anionic complexation. On the other hand, oxalic acid with a concentration of 0.1 M was chosen as a proper solvated complexant in the Cyanex 923 system. HCl solutions with concentrations of 1 and 2 M can properly strip germanium from the loaded Alamine 336 and Aliquat 336, respectively. In addition, 0.1 M NaOH was sufficient for germanium stripping from Cyanex 923. Consequently, it can be concluded that Aliquat 336 can be an economical and industry-friendly extractant for germanium solvent extraction from a mixed solution.
The application of inert and insulating low density polyethylene (LDPE) in electrochemical detection is null. However, in a recent study it was found that reactive species formed onto the surface of plasma-treated LDPE and other polymers promote the electrocatalytic oxidation of dopamine. In this work, we examine the role of plasma-treated LDPE as mediator in enzymatic glucose biosensors based on Glucose oxidase and glass carbon substrate. Results indicate that plasma-induced changes facilitate the electrocommunication between the enzyme and the substrate. The chronoamperometric response of these sensors prove their bifunctionality since the oxidation of glucose to gluconolactone, which is catalyzed by the GOx, coexists with the oxidation of dopamine that is electrocatalytized by the plasma activated LDPE surface.
"This is the peer reviewed version of the following article: Buendía JJ, Fabregat G, Castedo A, Llorca J, Alemán C. Plasma-treated polyethylene as electrochemical mediator for enzymatic glucose sensors: Toward bifunctional glucose and dopamine sensors. Plasma Process Polym. 2017;e1700133, which has been published in final form at https://doi.org/10.1002/ppap.201700133. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving