Modification of epoxy–anhydride thermosets using a hyperbranched poly(ester‐amide): I. Kinetic study

An epoxy‐anhydride formulation used for the coating of electrical devices was modified with a commercially available hyperbranched poly(ester‐amide), Hybrane? S2200, in order to improve the thermal degradability of the resulting thermoset and thus facilitate the recovery of substrate materials after use of the component. The curing kinetics of the unmodified and modified formulations were studied in detail with differential scanning calorimetry, Fourier transform infrared spectroscopy and rheology. The results suggest that S2200 gets incorporated into the network structure and the curing kinetics are accelerated by the presence of hydroxyl groups from S2200. Copyright © 2012 Society of Chemical Industry     

Simultaneous cationic polymerization and esterification of epoxy/anhydride system in the presence of polyoxometalate catalyst

Polyoxometalate exhibits high catalytic performance for the simultaneous cationic polymerization and esterification of epoxy resin when anhydride is introduced as a co-hardener. The selective catalysis effect of polyoxometalate and the reaction mechanism was studied by differential scanning calorimetry (DSC), mid-infrared spectroscopy (MIR), near-infrared spectroscopy (NIR) and generalized two-dimensional correlation analysis. The cationic polymerization is the dominating reaction in neat epoxy systems. Increasing the amount of polyoxometalate and the polarity of the diluents fastens the curing rate of epoxy resin. Esterification was found to be the preferred reaction once anhydride was employed. When polyoxometalate was blocked by amine to form salt, it performs as an excellent catalyst for esterification in epoxy-anhydride systems. The epoxy materials catalyzed by polyoxometalate show quite good performance compared with ordinary epoxy resins. Moreover, thermal degradation analysis (TGA) shows that polyoxometalate could significantly decrease the thermal degradation temperatures of cured epoxy resins.     

The Effect of the Degree of Branching in Hyperbranched Polyesters Used as Reactive Modifiers in Epoxy Thermosets

The effect of the degree of branching (DB) of a hyperbranched polyester (GBPEX) added as a modifier of new thermosets obtained from diglycidylether of bisphenol A has been studied. The use of ytterbium triflate as cationic initiator allows the hydroxyl chain‐ends in the GBPEX to become covalently linked to the matrix through the monomer activated propagation mechanism. The curing process has been studied by DSC and rheology. The DB of the modifier does not affect appreciably the thermal stability and the chemical reworkability but shrinkage exhibits a significant reduction on increasing the DB. Thermomechanical characteristics are also improved with increasing the DB of the modifier.

     

Long-term mechanical ventilation in amyotrophic lateral sclerosis

BACKGROUND: Acute respiratory insufficiency (ARI) with alveolar hypoventilation or incapacitating dyspnoea but without peripheral muscle involvement can be an early manifestation of respiratory involvement in amyotrophic lateral sclerosis (ALS). Some of these patients benefit from assisted ventilation. The object of this study was to analyse the results of long-term mechanical ventilation (LTMV) in ten patients with ALS. METHODS: A retrospective analysis of intensive care unit (ICU) or ambulant patients with ALS who underwent LTMV in a conventional hospital ward was performed. Erect and supine spirometry, blood gas analysis and pulse oximetry were performed before the start and during the course of ventilation. RESULTS: Ten patients on LTMV were included. Four from the ICU were ventilated via tracheostomy, and six ambulant patients had non-invasive (nasal) ventilation. In all cases, ventilation was performed in a conventional hospital ward. The ambulant patients improved symptomatically during ventilation, confirmed by measurement of gas exchange and of SaO2 by continuous pulse oximetry. Three of the ten patients survive in long-term care--two with nasal and one with tracheostomy ventilation. CONCLUSIONS: LTMV outside ICU was possible in ten patients, seven of whom returned home. Returning home is very difficult for patients dependent on a ventilator who lack family support.     

A computational modeling for real ecosystems based on P systems

In this paper, a P systems based general framework for modeling ecosystems dynamics is presented. Particularly, ecosystems are specified by means of multienvironment P systems composed of a finite number of environments, each of them having an extended P system with active membranes. The semantics is of a probabilistic type and it is implemented by assigning each rule of the system a probabilistic constant which depends on the environment and the run time. As a case study, two real ecosystems are described: scavenger birds in the Catalan Pyrenees and the zebra mussel (Dreissena Polymorpha) in Ribarroja reservoir (Spain).     

The effect of breed-production systems on the myosin heavy chain 1, the biochemical characteristics and the colour variables of Longissimus thoracis from seven Spanish beef cattle breeds

The effect of breed-production system on the myosin heavy chain 1 (MHC-I), the biochemical characteristics and the colour variables of longissimus thoracis (LT) from seven beef breeds was studied: Asturiana de la Monta?a (AM), Asturiana de los Valles (AV), Avile?a-Negra Ibérica (A-NI), Bruna dels Pirineus (BP), Morucha (MO), Pirenaica (PI) and Retinta (RE) (Age at slaughter between 368 and 541 days; carcass weight between 249 and 334 kg). Significant differences between breed-production systems were found for all traits evaluated. LT from the MO, a rustic type breed, was the most oxidative (MHC-I, 39.3%; isocitrate dehydrogenase activity, 52 nmol min(-1) mg(-1); pigment content, 188.4 μg acid haematin g(-1)) and showed a low L* value (32.6) and high a* and C* values (24 and 27.2, respectively). In terms of meat colour (L* and a*) the canonical discriminant analysis separated the breeds into two groups, the AV, the PI and the A-NI (the lightest ones) from the AM and the MO breeds (the reddest and darkest) whereas the BP showed an intermediate position. The RE and the A-NI were distinguished from the others by their high intramuscular fat content. Meat colour was affected by the muscle biochemical traits in the breed-production systems studied.     

A new two-stage curing system: Thiol-ene/epoxy homopolymerization using an allyl terminated hyperbranched polyester as reactive modifier

An allyl terminated hyperbranched polyester (HBP) was added to an epoxy formulation containing a trithiol compound to perform a thiol-ene click reaction. By this procedure a flexible thioether network was formed. The photoirradiation of the reactive mixture, which contained a cationic photoinitiator, converted the thioether network in a multifunctional thermal macroinitiator, capable to initiate the cure of the cycloaliphatic epoxy resin(CE) in a second thermal stage. Depending on the proportion of HBP, thermal or photocuring of the epoxy resin took place in different extent, leading to networks with different structures. The photocuring procedure was followed by FTIR and the thermal second stage by DSC. The materials obtained were characterized by DMTA, TGA and SEM. The addition of HBP-Allyl and the trithiol to the formulation allowed increasing the T_g on comparison with the neat epoxy thermoset. The system proposed constitutes a new two-stage dual photo-thermal curing procedure for cycloaliphatic epoxy resins with a thermal latent character.     

Influence of a cocoa-enriched diet on specific immune response in ovalbumin-sensitized rats

Previous studies in young rats have reported the impact of 3 weeks of high cocoa intake on healthy immune status. The present article describes the effects of a longer-term cocoa-enriched diet (9 weeks) on the specific immune response to ovalbumin (OVA) in adult Wistar rats. At 4 weeks after immunization, control rats produced anti-OVA antibodies, which, according their amount and isotype, were arranged as follows: IgG1 > IgG2a > IgM > IgG2b > IgG2c. Both cocoa diets studied (4% and 10%) down-modulated OVA-specific antibody levels of IgG1 (main subclass associated with the Th2 immune response in rats), IgG2a, IgG2c and IgM isotypes. Conversely, cocoa-fed rats presented equal or higher levels of anti-OVA IgG2b antibodies (subclass linked to the Th1 response). Spleen and lymph node cells from OVA-immunized control and cocoa-fed animals proliferated similarly under OVA stimulation. However, spleen cells from cocoa-fed animals showed decreased interleukin-4 secretion (main Th2 cytokine), and lymph node cells from the same rats displayed higher interferon-gamma secretion (main Th1 cytokine). These changes were accompanied by a reduction in the number of anti-OVA IgG-secreting cells in spleen. In conclusion, cocoa diets induced attenuation of antibody synthesis that may be attributable to specific down-regulation of the Th2 immune response.     

Rhamnolipids Obtained from a PHA-Negative Mutant of Pseudomonas aeruginosa 47T2 ΔAD: Composition and Emulsifying Behavior

Pseudomonas aeruginosa 47T2 (NCBIM 40044) synthesizes polyhydroxyalkanoic acids (PHAs) and rhamnolipids (Rhls). The knockout mutant for PHAs biosynthesis, P. aeruginosa 47T2 ΔAD prepared in this study, increased the cellular yield of Rhls production by 28 %. The Rhls mixture (composed up to eight homologs) reduced the water surface tension to 31.67 mN/m with a critical micelle concentration of 105 mg/L. The IC₅₀ (μg/mL) of the neutral red uptake assay and methylthiazol tetrazolium assay ranged between 53.9 and 72 μg/mL, which is similar to that of sodium dodecyl sulfate (SDS). Rhamnolipids had a lower hemolytic effect at 110.8 μg/ml than SDS, a commercial anionic surfactant, at 43.6 μg/mL. This suggests that the Rhls mixture could be used in topical pharmaceutical and cosmetic applications or cleansers as a biosurfactant. The emulsifying properties in water/oil dispersions were determined using ternary phase diagrams at 25 °C. Isopropyl myristate, soybean oil, olive oil and Casablanca oil were used as the oil components. Total emulsions were obtained with most of the oils.     

The 1st case in Spain of detection of occult squamous carcinoma using LIFE system

LIFE system (lung imaging fluorescence endoscope) is a new system of detection for early lung cancer using a He-Cd laser through a conventional fiberoptic bronchoscope. This system is able to capture and processing the autofluorescence from the bronchial mucosa and to show it in a video screen in real time. In the screen the normal tissue appears in green colour and the neoplastic tissue in brown colour. The first studies performed with LIFE system show the same specificity of the conventional bronchoscopy but the sensibility is 50% higher. In this paper we present the first case of detection of a occult squamous cell carcinoma with sputum and bronchial aspiration cytology positive for carcinoma but chest X ray, CT scanner and bronchoscopy negative for lung cancer. The LIFE system was able to detect carcinoma in the carina.