The Role of fast magnetosonic waves in the release and conversion via reconnection of energy stored by a current sheet

Using a simple two-dimensional, zero-beta model, we explore the manner by which reconnection at a current sheet releases and dissipates free magnetic energy. We find that only a small fraction (3%-11% depending on current sheet size) of the energy is stored close enough to the current sheet to be dissipated abruptly by the reconnection process. The remaining energy, stored in the larger-scale field, is converted to kinetic energy in a fast magnetosonic disturbance propagating away from the reconnection site, carrying the initial current and generating reconnection-associated flows (inflow and outflow). Some of this reflects from the lower boundary (the photosphere) and refracts back to the X-point reconnection site. Most of this inward wave energy is reflected back again, and continues to bounce between X-point and photosphere until it is gradually dissipated, over many transits. This phase of the energy dissipation process is thus global and lasts far longer than the initial purely local phase. In the process a significant fraction of the energy (25%-60%) remains as undissipated fast magnetosonic waves propagating away from the reconnection site, primarily upward. This flare-generated wave is initiated by unbalanced Lorentz forces in the reconnection-disrupted current sheet, rather than by dissipation-generated pressure, as some previous models have assumed. Depending on the orientation of the initial current sheet the wave front is either a rarefaction, with backward directed flow, or a compression, with forward directed flow

Meta-model Pruning

Large and complex meta-models such as those of Uml and its profiles are growing due to modelling and inter-operability needs of numerous\ud stakeholders. The complexity of such meta-models has led to coining\ud of the term meta-muddle. Individual users often exercise only a small\ud view of a meta-muddle for tasks ranging from model creation to construction\ud of model transformations. What is the effective meta-model that represents\ud this view? We present a flexible meta-model pruning algorithm and\ud tool to extract effective meta-models from a meta-muddle. We use\ud the notion of model typing for meta-models to verify that the algorithm\ud generates a super-type of the large meta-model representing the meta-muddle.\ud This implies that all programs written using the effective meta-model\ud will work for the meta-muddle hence preserving backward compatibility.\ud All instances of the effective meta-model are also instances of the\ud meta-muddle. We illustrate how pruning the original Uml metamodel\ud produces different effective meta-models

Pegylated lipid nanocapsules with improved drug encapsulation and controlled release properties

Drugs with poor lipid and water solubility are some of the most challenging to formulate in nanocarriers, typically resulting in low encapsulation efficiencies and uncontrolled release profiles. PEGylated nano- capsules (PEG-NC) are known for their amenability to diverse modifications that allow the formation of domains with different physicochemical properties, an interesting feature to address a drug encapsulation problem. We explored this problem by encapsulating in PEG-NC the promising anticancer drug candidate F10320GD1, used herein as a model for compounds with such characteristics. The nanocarriers were pre- pared from Miglyol®, lecithin and PEG-sterate through a solvent displacement technique. The resulting system was a homogeneous suspension of particles with size around 200 nm. F10320GD1 encapsulation was found to be very poor (<15%) if PEG-NC were prepared using water as continuous phase; but we were able to improve this value to 85% by fixing the pH of the continuous phase to 9. Interestingly, this modification also improved the controlled release properties and the chemical stability of the formulation during storage. These differences in pharmaceutical properties together with physicochemical data sug- gest that the pH of the continuous phase used for PEG-NC preparation can modify drug allocation, from the external shell towards the inner lipid core of the nanocapsules. Finally, we tested the bioactivity of the drug-loaded PEG-NC in several tumor cell lines, and also in endothelial cells. The results indicated that drug encapsulation led to an improvement on drug cytotoxicity in tumor cells, but not in non-tumor en- dothelial cells. Altogether, the data confirms that PEG-NC show adequate delivery properties for F10320GD1, and underlines its possible utility as an anticancer therapy.The authors would like to acknowledge financial support from CENIT-NANOFAR XS53 project, FAES Farma S.A. (Spain), Xunta de Galicia (Competitive Reference Ref. GRC2014/043, FEDER Funds) and the European Commission FP7 EraNet — EuroNanoMed Program-Instituto Carlos III (Lymphotarg pro- yect, Ref. PS09/02670). MGF was a recipient of an Isidro Parga Pondal contract

Polyacrylamide networks. Kinetic and structural studies by high field H-NMR with polymerization in situ

The crosslinking polymerization of acrylamide (AA) and N,N′-methylene-bis-acrylamide (BA) in aqueous solution at 22°C has been studied by H.R. H-NMR spectroscopy. The initial comonomer mixture was placed inside the NMR spectrometer probe head and the polymerization was followed for 10 hr. This procedure allows measurement of the instant composition of the residual comonomer mixture even during and after gelation and therefore to calculate the composition of the formed copolymer or network. When the reaction was finished, the structure of the most mobile part of the network was also analyzed

Polyacrylamide networks. Sequence distribution of crosslinker

The crosslinking copolymerization of acrylamide (AA) and N,N′-methylene-bis-acrylamide (BA) has been studied by high resolution ¹H-NMR with copolymerization in situ. This procedure allows calculation of the copolymer composition at zero degree of conversion and as a function of the polymerization time. Monomer reactivity ratios were calculated by the Kelen-Tüdös method in the pre-gel state and during gelation. Sequence distributions of both comonomers were then characterized.Financial support from CAICYT (Spain) under Grant No. 0528/84 is gratefully acknowledged

Lifeguard assistance at Spanish Mediterranean beaches: Jellyfish prevail and proposals for improving risk management

Although beaches can be hazardous environments, few studies have identified injuries in broad coastal areas. We performed a retrospective descriptive study of injuries and other services provided by lifeguards during 2012 along the Spanish Mediterranean beaches. The trend in jellyfish stings was also examined for the period 2008–2012 using a standardised Sting Index. Obtaining data relied on voluntary cooperation of local authorities, resulting in data provided from 183 cities out of 234 present in the study area and 760 beach lifeguard stations (LGS) out of about 1200. Lifeguard stations provided an average of 89 days of service per year, from late June to the beginning of September. A total of 176,021 injuries were reported, of which jellyfish stings were the main need for assistance with 59.7% (n = 116,887) of the injuries and 257.0/LGS, followed by wounds (14.4%, 50.9/LGS), and sunburn (3.3%, 15.8/LGS). Apart from attending injuries, beach lifeguard services provided 21,174 other services such as help to disabled people (57.9/LGS), blood pressure measurements (12.7/LGS), rescues at sea (6.5/LGS), lost children (5.7/LGS), and transfers to the hospital (4.6/LGS). Official reported fatalities for all the beaches in 2012 were 24. We proposed a Sting Index (SI) to allow comparisons of the incidence of stings between years and/or localities by standardising jellyfish stings by the total of all injuries. Historical data were consistent enough to calculate SI between 2010 and 2012 and showed an oscillating pattern without a clear trend (2008: 2.4, 2009: 1.3, 2010: 2.4, 2011: 2.0, 2012: 2.6). Estimation of total number of jellyfish stings for all the beaches present in the area would reach 184,558 for 2012. There were very few fatalities in comparison with other coastal regions, probably due to the combination of a calm sea, a low number of high dangerous situations, and a high percentage of lifeguarded beaches during the bathing season. Nevertheless, although Spanish Mediterranean beaches could be described as low risk, we propose measures to facilitate a precautionary management to prevent injuries based on a real-time beach assistance database of injuries to identify high-incidence assistance categories.This research was carried out under contract LIFE 08 NAT ES 0064 (to CB and VF) co-financed by the European Commission (www.cubomed.eu), the Ministerio de Agricultura, Alimentación y Medio Ambiente (Dirección General de Sostenibilidad de la Costa y el Mar) contract 2013/28-5158, the Dirección General del Agua of the Regional Government of Valencia (grant T7588000/512.10) and the Fundación Biodiversidad (grant LIFE Cubomed 2013/2014)

Structure-activity relationship study of cationic carbosilane dendritic systems as antibacterial agents

This work focuses on the antibacterial activity against Gram-positive Staphylococcus aureus and Gramnegative Escherichia coli and the hemolytic properties of two types of ammonium cationic carbosilane systems: dendrimers and dendrons. The effects of: i) the generation, ii) the type of peripheral groups near the cationic charges (a SiMe2 moiety or a S atom depending on the synthetic procedure, hydrosilylation or thiol-ene addition, respectively), iii) the core of dendrimers (polyphenoxo vs. Si atom) and iv) the focal point of dendrons (-N3, -NH2, -OH) have been assessed. The structure-activity relationship analysis indicates the importance of an adequate balance between the hydrophilic and lipophilic fragments of these molecules to reach the best antibacterial activity. Regarding hemolysis, lowest toxicity values were registered for dendritic systems with a sulfur atom close to the surface and, in the particular case of dendrons, for those with a hydroxyl focal point. One dendrimer and one dendron, both bearing a sulfur atom close to the surface, scored best in the activity-toxicity relationship analysis and were chosen for resistance assays. No changes in the inhibitory and bactericidal capacity in the case of the dendron and only a slight increase of these values for the dendrimer were observed after 15 subculture cycles. Furthermore, these two compounds stayed active towards different strains of resistant bacteria and avoid formation of biofilm at concentrations over the minimum inhibitory concentration (MIC).Ministerio de Economía y Empres

Strategies for penicillin V dendronization with cationic carbosilane dendrons and study of antibacterial properties.

Strategies to synthesize a cationic carbosilane dendron containing the antibiotic penicillin V potassium salt (PenVK) at the focal point are discussed. The preparation of such a compound requires the use of systems with no donor atoms such as N or S in their framework, because their presence favours the rupture of the penicillin beta-lactam ring. The antibacterial activity of the new dendron containing ammonium groups, at the periphery, and the PenV moiety, at the focal point, against gram-positive Staphylococcus aureus strains was evaluated. These results were compared with those obtained for free PenVK, a related cationic dendron without a penicillin moiety at the focal point, and also compared with an equimolar mixture of this last dendron with free PenV. The data obtained indicate that, on one hand, the conjugation or interaction of PenV with cationic dendrons reduces its activity in comparison with free PenVK. On the other hand, the penicillin dendron is able to release the antibiotic in the presence of esterease, due to the breaking of the ester bond in this derivative.Ministerio de Economía y Empres

Selective Fractionation And Isolation Of Allelopathic Compounds From Helianthus Annuus L. Leaves By Means Of High-Pressure Techniques

The allelopathic potential of Helianthus annuus L. leaves was study based on bio-directed chemical fractionation approach. Aerial parts of H. annuus were extracted by means of SFE using supercritical carbon dioxide (scCO2) and ESE using CO2+50% EtOH/H2O (varying ethanol in water from 0 to 100%). Extractions were carried out at 400 bar, 55 °C, 20 g/min and for 4 h. Then, extracts were fractionated in three separators at the following conditions: S1: 200 bar/45 °C; S2: 90 bar/40 °C; and S3: 1 atm/30 °C. ESE obtained higher overall yields than scCO2 and the use of water as cosolvent (CO2+50% H2O) resulted in a S3 fraction free from chlorophylls and rich in bioactive compounds. 14 compounds, including fatty acids, terpenes, flavonoids and heliannuols, were isolated from this fraction. After performing the bioassay on pure compounds, heliannuol D, tambulin, pinoresinol and sesquiterpene 10-oxo-isodauc-3-en-15-al showed the most effective inhibitor profiles