Nanofiber mats functionalized with Mentha piperita essential oil stabilized in a chitosan-based emulsion designed via an electrospinning technique

A nanostructured device based on poly(vinyl alcohol) (PVA) loaded with a cross-linked chitosan (CH) emulsion, soy lecithin, and peppermint essential oil (Mentha piperita) was designed for topical applications using an electrospinning instrument coupled to a rotary drum collector. Different suspensions were obtained by varying the PVA to emulsion ratio (PVA:Em) 87.5:12.5, 82:18, and 75:25, using a PVA solution as a control. ATR-FTIR spectra confirmed the interactions among the components of the system. Scanning electron microscopy (SEM) of the mats evinced that the aligned fiber diameter decreased with higher proportions of emulsion while dynamic mechanical analysis (DMA) revealed a decrease in the storage modulus. The entrapment of the functionalized emulsions not only improved the elongation of the matrices but also provided them with greater structural integrity compared to the single PVA matrix. The most favorable formulation in terms of mechanical properties was found to be the 82:18 ratio. After 1 h of close contact between the 82:18 matrix and a porcine skin explant, the latter was examined by confocal microscopy, which revealed the localization of the essential oil mainly on the surface of the stratum corneum (SC).However, after 7 h of contact, the distribution of the peppermint EO throughout the viable epidermis was observed, which was further supported by ATR-FTIR studies. Tailored electrospun matrices would have potential applications as devices for topical or transdermal treatments due to their vehiculization role that allows the diffusion of peppermint essential oil as a skin penetration enhancer.Fil: Lamarra, Javier Andres. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Rivero, Sandra G. M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Pinotti, Adriana Noemi. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Lopez, Daniel. Instituto en Ciencia y Tecnología de Polímeros; Españ

Electrospun nanofibers of poly(vinyl alcohol) and chitosan-based emulsions functionalized with cabreuva essential oil

Among the essential oils (EOs), the cabreuva essential oil extracted from the wood of Myrocarpus fastigiatus, is a promising compound for potential applications in the field of pharmaceuticals and food packaging. To overcome the low solubility of cabreuva EO and to protect it, a two-step process, emulsion formation compound by chitosan, SDS, and PVA, and subsequent ionic crosslinking with sodium citrate, was proposed. The formulation containing 0.75% of chitosan and 1% of SDS proved to be the most stable. An alternative to produce nanostructures and encapsulate the EO is the fiber formation through the electrospinning method. The system composed by a PVA solution assembled with crosslinked emulsions modified the viscosity, influencing the morphology of the obtained nanofibers. The advantage of the electrospun nanofibers was their ability to be an effective carrier of the cabreuva EO and the capacity of controlling the compound release that proved an effective activity against broad spectra of micro-organisms (Candida albicans, E. coli, S. aureus, and S. epidermidis). The Gallagher-Corrigan model, used to fit the release profiles of matrices in contact with increasing ethanol proportion from 25:75 to 50:50 showed higher Kb in relation to k suggesting that the polymer swelling played an increasingly prominent role in the EO delivery. The developed nanostructures would be materials with potential applications in the biomedical field.Fil: Lamarra, Javier Andres. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Calienni, Maria Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología - Universidad Nacional de Quilmes - GBEyB | Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología - Universidad Nacional de Quilmes - GBEyB | Universidad Nacional de La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología - Universidad Nacional de Quilmes - GBEyB; ArgentinaFil: Rivero, Sandra G. M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Pinotti, Adriana Noemi. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3

We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report that the SP transition is reentrant in the vicinity of the critical concentration x_c. This is manifested by broadening of the SP dimerization superlattice peaks below the reentrance temperature, T_r, which may mean either the complete loss of the long-range SP order or the development of a short-range ordered component within the long-range ordered SP state. Marked hysteresis and very large relaxation times are found in the samples with Mg concentrations in the vicinity of x_c. The reentrant transition is likely related to the competing Neel transition which occurs at a temperature similar to T_r. We argue that impurity-induced competing interchain interactions play an essential role in these phenomena.Comment: 5 pages, 4 embedded eps figure

Aplicación de sistemas bicapa nanocompuestos para la conservación de harina de nuez

Una alternativa para mejorar las propiedades de un envase es a través de la obtención de un sistema bicapa que combina las ventajas de dos o más materiales poliméricos1. Por otra parte, una estrategia para escalar la formación de bicapas es el procesamiento mediante termocompresión. En este contexto, los objetivos del trabajo fueron: i) diseñar sistemas bicapa a base de películas nanocompuestas de quitosano y alcohol polivinílico y estudiar sus propiedades fisicoquímicas ii) aplicar los sistemas obtenidos como material de envase a una harina de nuez y iii) estudiar la estabilidad oxidativa del producto bajo condiciones controladas de humedad y temperatura.Fil: Lamarra, Javier Andres. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Rivero, Sandra G. M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Pinotti, Adriana Noemi. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaIV Workshop de Polímeros Biodegradables y BiocompuestosMar del PlataArgentinaInstituto de Investigaciones en Ciencia y Tecnología de los Materiale

X-ray scattering study of two length scales in the critical fluctuations of CuGeO3

The critical fluctuations of CuGeO$_3$ have been measured by synchrotron x-ray scattering, and two length scales are clearly observed. The ratio between the two length scales is found to be significantly different along the $a$ axis, with the $a$ axis along the surface normal direction. We believe that such a directional preference is a clear sign that surface random strains, especially those caused by dislocations, are the origin of the long length scale fluctuations.Comment: 5 pages, 4 figures, submitted to PR

Operative and middle-term results of cardiac surgery in nonagenarians: A bridge toward routine practice

Background: Age >90 years represents in many centers an absolute contraindication to cardiac surgery. Nonagenarians are a rapidly growing subset of the population posing an expanding clinical problem. To provide helpful information in regard to this complex decision, we analyzed the operative and 5-year results of coronary and valvular surgical procedures in these patients. Methods and Results: We retrospectively reviewed 127 patients aged ≥90 years who underwent cardiac surgery within our hospital group in the period 1998 to 2008. Kaplan-Meier and multiple logistic regression analyses were performed. A longer follow-up than most published studies and the largest series published thus far are presented. Mean age was 92 years (range, 90 to 103 years). Mean logistic EuroSCORE was 21.3±6.1. Sixty patients had valvular surgery (including 11 valve repairs), 49 patients had coronary artery bypass grafting, and 18 had valvular plus coronary artery bypass grafting surgery (55 left mammary artery grafts implanted). Forty-five patients (35.4%) were operated on nonelectively. Operative mortality was 13.4% (17 cases). Fifty-four patients (42.5%) had a complicated postoperative course. There were no statistically significant differences in the rate and type of complications between patient strata on the basis of type of surgery performed. Nonelective priority predicted a complicated postoperative course. Predictors of operative mortality were nonelective priority and previous myocardial infarction. Kaplan-Meier survival estimates at 5 years were comparable between patient groups on the basis of procedure performed. Conclusions: Although the rate of postoperative complications remains high, cardiac surgery in nonagenarians can achieve functional improvement at the price of considerable operative and follow-up mortality rates. Cardiac operations in these very elderly subjects are supported if appropriate selection is made and if the operation is performed earlier and electively. Our results should contribute to the development of guidelines for cardiac operations in nonagenarians. © 2010 American Heart Association. All rights reserved

Recycled Aggregate Concrete including Various Contents of Metakaolin: Mechanical Behavior

This experimental research investigates the effect of utilizing metakaolin (MK) on the behavior of recycled aggregate concrete (RAC). The RAC incorporates recycled coarse aggregate (RCA) originated from crushing construction and demolition waste. The investigated parameters were RCA and MK contents. Tests of workability and mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were conducted to evaluate the influence of MK on workability and mechanical behavior of RAC. In total, 19 mixes were prepared. These mixes are divided into four groups. Group zero (G0) includes a reference mix containing normal coarse aggregate (NCA) and 3 mixes made with 35%, 70%, and 100% of RCA. Each one of the other three groups (G1, G2, and G3) was made with one content of the three contents of RCA, and each group includes five mixes made with the contents of 4%, 8%, 12%, 16%, and 20% of MK. Empirical models among the mechanical properties of the RAC mixes were developed and compared with models of standard codes of practice such as ACI 318, BS 8110, and Eurocode 2. It was found that MK reduces the workability of the RAC mixes. Nonetheless, the outcomes reveal that MK can improve the compressive, splitting tensile, and flexural strengths and the elastic modulus of RAC. This strength improvement enhances as the content of MK increases. The proposed models for the mechanical properties of RAC made with MK showed good correlations. The developed model for modulus of elasticity is quite close to the Eurocode 2 model, whereas the models of ACI 318 and BS 8110 underestimate the values of the modulus of elasticity

Virtual unrolling and deciphering of Herculaneum papyri by X-ray phase-contrast tomography

A collection of more than 1800 carbonized papyri, discovered in the Roman 'Villa dei Papiri' at Herculaneum is the unique classical library survived from antiquity. These papyri were charred during 79 A.D. Vesuvius eruption, a circumstance which providentially preserved them until now. This magnificent collection contains an impressive amount of treatises by Greek philosophers and, especially, Philodemus of Gadara, an Epicurean thinker of 1st century BC. We read many portions of text hidden inside carbonized Herculaneum papyri using enhanced X-ray phase-contrast tomography non-destructive technique and a new set of numerical algorithms for 'virtual-unrolling'. Our success lies in revealing the largest portion of Greek text ever detected so far inside unopened scrolls, with unprecedented spatial resolution and contrast, all without damaging these precious historical manuscripts. Parts of text have been decoded and the 'voice' of the Epicurean philosopher Philodemus is brought back again after 2000 years from Herculaneum papyri

‘Priming’ exercise and O2 uptake kinetics during treadmill running

We tested the hypothesis that priming exercise would speed kinetics during treadmill running. Eight subjects completed a square-wave protocol, involving two bouts of treadmill running at 70% of the difference between the running speeds at lactate threshold (LT) and max, separated by 6-min of walking at 4 km h−1, on two occasions. Oxygen uptake was measured breath-by-breath and subsequently modelled using non-linear regression techniques. Heart rate and blood lactate concentration were significantly elevated prior to the second exercise bout compared to the first. However, kinetics was not significantly different between the first and second exercise bouts (mean ± S.D., phase II time constant, Bout 1: 16 ± 3 s vs. Bout 2: 16 ± 4 s; slow component amplitude, Bout 1: 0.24 ± 0.10 L min−1vs. Bout 2: 0.20 ± 0.12 L min−1; mean response time, Bout 1: 34 ± 4 s vs. Bout 2: 34 ± 6 s; P > 0.05 for all comparisons). These results indicate that, contrary to previous findings with other exercise modalities, priming exercise does not alter kinetics during high-intensity treadmill running, at least in physically active young subjects. We speculate that the relatively fast kinetics and the relatively small slow component in the control (‘un-primed’) condition negated any enhancement of kinetics by priming exercise in this exercise modality