The increase of renewables in power sector, together with the increase of their electricity share in final energy consumption, is changing our perception about energy security with diverse and contradictory statements. The Portuguese security of electricity supply is analyzed in this study by comparing selected indicators for 2. years before and after the high increase of onshore wind since 2005. Our goal is to find how the security of electricity supply was impacted by the penetration of renewables, taking a supply chain approach. Our analysis highlights that the penetration of renewables has decreased the energy dependence of the power sector by more than 20% between 2004 and 2011, while risks related to the concentration of natural gas suppliers and to the still-high share of fossil fuels suffering from price volatility are discussed. We observed a significant improvement in power interconnections with Spain, as well as an increase of the de-rated generation capacity margin, allowing proper management of renewable power intermittency if necessary, thereby improving power security. Although the share of intermittent renewables almost quadrupled in total installed capacity between those years, the indicators reveal an improvement in the quality of transport and distribution when delivering electricity to end-users. Although electricity prices increased, mainly due to taxes, the lack of energy efficiency is an aspect deserving improvement to alleviate the pressure on electricity security, mainly at high peak demands.

Iron oxide nanoparticles are having been extensively investigated for several biomedical applications such as hyperthermia and magnetic resonance imaging. However, one of the biggest problems of these nanoparticles is their aggregation.
Taking this into account, in this study the influence of three different surfactants (oleic acid, sodium citrate and Triton X-100) each one with various concentrations in the colloidal solutions stability was analyzed by using a rapid and facile method, the variation in the optical absorbance along time.
The synthesized nanoparticles through chemical precipitation showed an average size of 9 nm and a narrow size distribution. X-ray diffraction pattern and Fourier Transform Infrared analysis confirmed the presence of pure magnetite. SQUID measurements showed superparamagnetic properties with a blocking temperature around 155 K. In addition it was observed that neither sodium citrate nor Triton X-100 influences the magnetic properties of the nanoparticles. On the other hand, oleic acid in a concentration of 64 mM decreases the saturation magnetization from 67 to 45 emu/g. Oleic acid exhibits a good performance as stabilizer of the iron oxide nanoparticles in an aqueous solution for 24 h, for concentrations that lead to the formation of the double layer.

Iron oxide nanoparticles are having been extensively investigated for several biomedical applications such as hyperthermia and magnetic resonance imaging. However, one of the biggest problems of these nanoparticles is their aggregation.

Taking this into account, in this study the influence of three different surfactants (oleic acid, sodium citrate and Triton X-100) each one with various concentrations in the colloidal solutions stability was analyzed by using a rapid and facile method, the variation in the optical absorbance along time.

The synthesized nanoparticles through chemical precipitation showed an average size of 9 nm and a narrow size distribution. X-ray diffraction pattern and Fourier Transform Infrared analysis confirmed the presence of pure magnetite. SQUID measurements showed superparamagnetic properties with a blocking temperature around 155 K. In addition it was observed that neither sodium citrate nor Triton X-100 influences the magnetic properties of the nanoparticles. On the other hand, oleic acid in a concentration of 64 mM decreases the saturation magnetization from 67 to 45 emu/g. Oleic acid exhibits a good performance as stabilizer of the iron oxide nanoparticles in an aqueous solution for 24 h, for concentrations that lead to the formation of the double layer.

The electrospinning of polycaprolactone (PCL) dissolved in glacial acetic acid and the characterization of the resultant nonwoven fiber mats is reported in this work. For comparison purposes, PCL fiber mats were also obtained by electrospinning the polymer dissolved in chloroform. Given the processing parameters chosen, results show that 14 and 17 wt % PCL solutions are not viscous enough and yield beaded fibers, 20 and 23 wt % solutions give rise to high quality fibers and 26 wt % solutions yield mostly irregular and fused fibers. The nonwoven mats are highly porous, retain the high tensile strain of PCL, and the fibers are semicrystalline. Cells adhere and proliferate equally well on all mats, irrespective of the solvent used in their production. In conclusion, mats obtained by electrospinning PCL dissolved in acetic acid are also a good option to consider when producing scaffolds for tissue engineering. Moreover, acetic acid is miscible with polar solvents, which may allow easier blending of PCL with hydrophilic polymers and therefore achieve the production of electrospun nanofibers with improved properties.

We investigated imidazolium-based ionic liquid (IL) interactions with human serum albumin (HSA) to discern the level of cation interactions towards protein stability. STD-NMR spectroscopy was used to observe the imidazolium ILs protons involved in direct binding and to identify the interactions responsible for changes in Tm as accessed by differential scanning calorimetry (DSC). Cations influence protein stability less than anions but still significantly. It was found that longer alkyl side chains of imidazolium-based ILs (more hydrophobic) are associated with a higher destabilisation effect on HSA than short-alkyl groups (less hydrophobic). The reason for such destabilisation lies on the increase surface contact area of the cation with the protein, particularly on the hydrophobic contacts promoted by the terminus of the alkyl chain. The relevance of the hydrophobic contacts is clearly demonstrated by the introduction of a polar moiety in the alkyl chain: a methoxy or alcohol group. Such structural modification reduces the degree of hydrophobic contacts with HSA explaining the lesser extent of protein destabilisation when compared to longer alkyl side chain groups: above [C2mim]+. Competition STD-NMR experiments using [C2mim]+, [C4mim]+ and [C2OHmim]+ also validate the importance of the hydrophobic interactions. The combined effect of cation and anion interactions was explored using 35Cl NMR. Such experiments show that the nature of the cation has no influence in the anion-protein contacts, still the nature of the anion modulates the cation-protein interaction. Herein we propose that more destabilising anions are likely to be a result of a partial contribution from the cation as a direct consequence of the different levels of interaction (cation-anion pair and cation-protein).

With a 4f6 electronic configuration, europium ions in the trivalent charge state are known to be efficient activators in wide band gap matrices. Embedded in the aluminophosphate (Li2O–BaO–Al2O3–La2O3–P2O5) glasses the optically activated Eu3+ ions lead to intense room temperature orange/red luminescence with 16–23 Cd/m2 by using ultraviolet pumping. The as-prepared and heat treated europium doped glasses for temperatures below and above Tg were studied by room temperature Raman spectroscopy, absorption, photoluminescence excitation, temperature dependent and time dependent photoluminescence. When the samples are excited by 325 nm wavelength photons, an enhancement of the red luminescence intensity by ca. one order of magnitude was found to occur for temperatures between 14 K and 350 K, for all the doped glasses. On the other hand, by using resonant excitation on the 5L6 Eu3+ excited state (λexc~390 nm) the ion emission intensity was found to be nearly constant for temperatures up to 500 K. For higher temperatures a steeper decrease of the luminescence intensity occurs due to non-radiative competitive channels described by activation energies of ca. 235 meV and 450 meV by using 325 and 390 nm wavelength photons as excitation, respectively. The lifetime of the 5D0 level in these glasses is ca. 2.93 ms. A discussion of the thermal population and de-excitation mechanisms is performed.

The bacterium Geobacter sulfurreducens displays an extraordinary respiratory versatility underpinning the diversity of electron donors and acceptors that can be used to sustain anaerobic growth. Remarkably, G. sulfurreducens can also use as electron donors the reduced forms of some acceptors, such as the humic substance analog anthraquinone-2,6-disulfonate (AQDS), a feature that confers environmentally competitive advantages to the organism. Using UV-visible and stopped-flow kinetic measurements we demonstrate that there is electron exchange between the triheme cytochrome PpcA from Gs and AQDS. 2D-(1)H-(15)N HSQC NMR spectra were recorded for (15)N-enriched PpcA samples, in the absence and presence of AQDS. Chemical shift perturbation measurements, at increasing concentration of AQDS, were used to probe the interaction region and to measure the binding affinity of the PpcA-AQDS complex. The perturbations on the NMR signals corresponding to the PpcA backbone NH and heme substituents showed that the region around heme IV interacts with AQDS through the formation of a complex with a definite life time in the NMR time scale. The comparison of the NMR data obtained for PpcA in the presence and absence of AQDS showed that the interaction is reversible. Overall, this study provides for the first time a clear illustration of the formation of an electron transfer complex between AQDS and a G. sulfurreducens triheme cytochrome, shedding light on the electron transfer pathways underlying the microbial oxidation of humics.

Industrial and urban activities yield large amounts of contaminated groundwater, which present a major health issue worldwide. Infectious diseases are the most common health risk associated with drinking-water and wastewater remediation is a major concern of our modern society. The field of wastewater treatment is being revolutionized by new nano-scale water disinfection devices which outperform most currently available technologies. In particular, iron oxide magnetic nanoparticles (MNPs) have been widely used in environmental applications due to their unique physical–chemical properties. In this work, poly(ethylene) glycol (PEG)-coated MNPs have been functionalized with (RW)3, an antimicrobial peptide, to yield a novel magnetic-responsive support with antimicrobial activity against Escherichia coli K-12 DSM498 and Bacillus subtilis 168. The magnetic-responsive antimicrobial device showed to be able to successfully disinfect the surrounding solution. Using a rapid high-throughput screening platform, the minimal inhibitory concentration (MIC) was determined to be 500 μM for both strains with a visible bactericidal effect.

FucoPol, a fucose-containing extracellular polysaccharide (EPS) produced by bacterium Enterobacter A47 using glycerol as the carbon source, was employed as a coating material for magnetic particles (MPs), which were subsequently functionalized with an artificial ligand for the capture of antibodies. The performance of the modified MPs (MP–EPS-22/8) for antibody purification was investigated using direct magnetic separation alone or combined with an aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and dextran. In direct magnetic capturing, and using pure protein solutions of human immunoglobulin G (hIgG) and bovine serum albumin (BSA), MP–EPS-22/8 bound 120 mg hIgG g−1 MPs, whereas with BSA only 10 ± 2 mg BSA g−1 MPs was achieved. The hybrid process combining both the ATPS and magnetic capturing leads to a good performance for partitioning of hIgG in the desired phase as well as recovery by the magnetic separator. The MPs were able to bind 145 mg of hIgG g−1 of particles which is quite high when compared with direct magnetic separation. The theoretical maximum capacity was calculated to be 410 ± 15 mg hIgG adsorbed g−1 MPs with a binding affinity constant of 4.3 × 104 M−1. In multiple extraction steps, the MPs bound 92% of loaded hIgG with a final purity level of 98.5%. The MPs could easily be regenerated, recycled and re-used for five cycles with only minor loss of capacity. FucoPol coating allowed both electrostatic and hydrophobic interactions with the antibody contributing to enhance the specificity for the targeted products.

Magnetic core coatings modify the efficiency of nanoparticles used as contrast agents for MRI. In studies of these phenomena, care should be given to take into account possible effects of the specific micro-environment where coated nanoparticles are embedded. In the present work, the longitudinal and transverse relaxivities of superparamagnetic iron oxide nanoparticles stabilized with short-chain polyethylene glycol molecules (PEGylated SPIONs) were measured in a 7T magnetic field. PEGylated SPIONs with two different diameters (5 and 10nm) were studied. Two different PEGylated magnetoliposomes having liposome bilayer membranes composed of egg-phosphatidylcholine, cholesterol and 1,2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy PEG-2000] were also studied for their relaxivities, after being loaded with the PEGylated SPION of 5 or 10nm. This type of liposomes is known to have long residence time in bloodstream that leads to an attractive option for therapeutic applications. The influence of the magnetic core coating on the efficiency of the nanosystem as a negative contrast agent for MRI was then compared to the cumulative effect of the coating plus the specific micro-environment components. As a result, it was found that the PEGylated magnetoliposomes present a 4-fold higher efficiency as negative contrast agents for MRI than the PEGylated SPION.

Cancer development is amultistep process in which exosomes play important roles. Exosomes are small vesicles formed in vesicular bodies in the endosomal network. The major role of exosomes seems to be the transport of bioactive molecules between cells. Depending on the cell of origin, exosomes are implicated in the regulation of several cellular events, with phenotypic consequences in recipient cells. Cancer derived exosomes (CCEs) are important players in the formation of the tumour microenvironment by (i) enabling the escape of tumour cells to immunological system and help initiating the inflammatory response; (ii) acting in the differentiation of fibroblasts and mesenchymal cells into myofibroblasts; (iii) triggering the angiogenic process; and (iv) enhancing the metastatic evolution of the tumour by promoting epithelial to mesenchymal transformation of tumour cells and by preparing the tumour niche in the new anatomical location. Since the finding that exosomes content resembles that of the cell of origin, they may be regarded as suitable biomarkers for cancer diagnosis, allowing for diagnosis and prognosis via a minimal invasive procedure. Exosome involvement in cancer may open new avenues regarding therapeutics, such as vectors for targeted drug delivery.

International Journal of Mass Spectrometry, 348 (2013) 1-8. doi:10.1016/j.ijms.2013.02.011

Li2O–BaO–Al2O3–La2O3–P2O5 glasses optically activated with rare earth ions with the 4f5, and 4f8 electronic configuration (Sm3+ and Tb3+, respectively) were analyzed by Raman spectroscopy, absorption, excitation photoluminescence, decay curves and temperature dependent photoluminescence. The spectroscopic characteristics of the as-prepared and heat treated samples at temperatures below and above Tg were studied as well as their room temperature photometric properties under ultraviolet excitation. All the doped glasses exhibit typical signatures of the lanthanides in their trivalent charge state. For the samarium doped glass heat treated at 250 °C (lower than Tg) the Sm2+ luminescence was also observed. The analysis of the luminescence efficiency was performed in the interval range of 14 K to room temperature, where the integrated intensity of the luminescence was found to decrease for the Sm3+ and Tb3+ ions in the studied temperature range. Luminescence decay curves were found to be non-exponential for the 4G5/2 → 6H7/2 and5D3 → 7F4 transitions of the Sm3+ and Tb3+ ions, respectively. The results strongly suggest the occurrence of energy transfer processes through cross relaxation phenomena, mediated by dipole–dipole interaction in all the studied samples. The decay of the 5D4 → 7F5 emission of the Tb3+ ions was found to be single exponential with a time constant of ∼3.1 ms. Based on the spectroscopic characteristics, models for recombination processes are proposed. The room temperature luminance photometric properties with ultraviolet excitation show that the samarium doped glasses have much lower luminance intensity (around 0.3 Cd/m2) when compared with the 6–7 Cd/m2 observed for the terbium doped ones.

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The development of nanoscaled materials has deserved a remarkable interest for biomedical applications. Biological tissues are essentially composite materials with particular mechanical properties that should be carefully considered during the design of innovative biomedical scaffolds. Electrospun membranes are often found in medical applications due to its high specific surface which creates a 3D porous structure that mimics the native extracellular matrix. These electrospun membranes can also be designed to have enhanced mechanical properties, biocompatibility and cellular response making them appealing and inspiring to be used in composites materials.
This paper reviews the new insights in the development of advanced nanostructured composites materials based on electrospun fibers. From tissue engineering to bioelectronics, these composite materials can be found in the most promising research developments for the medical applications.