Characterization of a high strain composite material

L'Garde has designed and developed a high-strain composite material consisting of car- bon FIbers embedded in a silicone matrix. The behavior of this material is significantly different from standard composites and the paper presents special test methods to measure the properties of this material. It is found that rule of mixtures estimates are quite accurate for the longitudinal moduli in tension and bending, but less accurate for compression. The Poisson's ratio prediction is also not accurate. Regarding the strength of the composite, it is found that conservative predictions of tensile and compressive strengths can be obtained respectively from the Weibull distribution of the strength of a single fiber combined with a simple bundle theory, and the elastic fiber microbuckling stress

A novel barley β-glucan extract (Glucagel TM) in combination with flax or coconut oil influences cholesterol and triglyceride levels in growing rats

A 2 x 2 factorial arrangement of treatments was used to test the hypothesis that inclusion of a novel P-glucan extract (GlucagelTM) in cholesterol-free synthetic diets containing coconut oil or flax oil would lower circulating total cholesterol (TC) and triglyceride (TG) levels in growing rats. Inclusion of Glucagel™ (100 g/kg) tended to decrease TC levels (P=0.07), however TC level was not influenced by oil type (P>0.05). A significant interaction (P0.05), respectively. Faecal digestibility of fat was reduced by 7% (P=0.08) in rats fed coconut oil plus P-glucan. These data suggest that reduced TG levels caused by addition of p-glucan may be mediated in part by reduced fat digestion in the small intestine, an effect most likely caused by the unique gel-forming properties of Glucagel

Adaptation Strategies and Microwave Drying of Amaranth Species with a High Nutritional Value to the Ecuadorian Andean Region

In the Andean region of Ecuador, amaranth is a key species not only for its high nutritional value but also for its association with Ecuadorian culture, since it is one of the main indigenous crops of the pre-Columbian era. Over the time, the cultivation of this species ceased for several reasons result. However, in recent years, a number of strategies have been developed to retrieve it on a national level. In accordance with these strategies, the “Amaranth Improvement Program for Cotopaxi” (PROMAC) is being developed at the Technical University of Cotopaxi, with the main objective of selecting varieties with high levels of biologically active substances. This program is been executed through two main lines of investigation: (a) selection of varieties of amaranth of high nutritional value and (b) the improvement of techniques for conservation of the seeds. This chapter analyzes and shows the main results obtained to date from the study of eight varieties of amaranth seeds and the drying of one of the seeds by means of microwave energy in order to improve its conservation. In the light of the results obtained, the strategies to develop the following research lines within the PROMAC framework are exposed

Long-distance migration and venting of methane from the base of the hydrate stability zone

\ua9 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world

Topographical control of the source‐sink and wind stress‐driven planetary geostrophic circulation in a polar basin

The effects of topography on the barotropic circulation in a polar basin are examined analytically and numerically. New approximate linear analytical solutions are presented for steady‐state wind and boundary forced barotropic planetary geostrophic circulation in a circular polar basin with a step shelf. The solutions are obtained by retaining the full spherical geometry in the derivation of the forced potential vorticity equation; thereafter the colatitude is fixed in the coefficients of this governing equation. The accuracy of the analytical solutions is evaluated by comparing them with the equivalent numerical solutions obtained using the NEMO modeling system. Subsequently, the impact of a nonuniform width shelf on source‐sink‐driven circulation is investigated numerically. The equipartition of fluid entering the source strait into cyclonic and anticyclonic shelf currents, exiting the basin at the sink strait, in a basin with a uniform width shelf is shown to be modified when the shelf width varies. In general, the wider shelf supports a current with larger transport, irrespective of the azimuthal extent of the wider shelf. The study concludes with a numerical investigation of wind‐driven circulation in a basin with a step shelf, three straits, and a transpolar ridge, a prototype Arctic Ocean simulation. Topographic steering by the ridge supports a transpolar drift current, the magnitude of which depends on the ridge height. Without the ridge, the transpolar drift current is absent and the circulation is confined to gyres on the shelf and in the deep basin

Water surface height determination with a GPS wave glider: a demonstration in Loch Ness, Scotland

A geodetic GPS receiver has been installed on a Wave Glider, an unmanned water surface vehicle. Using kinematic precise point positioning (PPP) GPS, which operates globally without directly requiring reference stations, surface heights are measured with ~0.05-m precision. The GPS Wave Glider was tested in Loch Ness, Scotland, by measuring the gradient of the loch’s surface height. The experiment took place under mild weather, with virtually no wind setup along the loch and a wave field made mostly of ripples and wavelets. Under these conditions, the loch’s surface height gradient should be approximately equal to the geoid slope. The PPP surface height gradient and that of the Earth Gravitational Model 2008 geoid heights do indeed agree on average along the loch (0.03 m km−1). Also detected are 1) ~0.05-m-sized height changes due to daily water pumping for hydroelectricity generation and 2) high-frequency (0.25–0.5 Hz) oscillations caused by surface waves. The PPP heights compare favorably (~0.02-m standard deviation) with relative carrier phase–based GPS processing. This suggests that GPS Wave Gliders have the potential to autonomously determine centimeter-precise water surface heights globally for lake modeling, and also for applications such as ocean modeling and geoid/mean dynamic topography determination, at least for benign surface states such as those encountered during the reported experiment

Structure of the vacuum states in the presence of isovector and isoscalar pairing correlations

The long standing problem of proton-neutron pairing and, in particular, the limitations imposed on the solutions by the available symmetries, is revisited. We look for solutions with non-vanishing expectation values of the proton, the neutron and the isoscalar gaps. For an equal number of protons and neutrons we find two solutions where the absolute values of proton and neutrons gaps are equal but have the same or opposite sign. The behavior and structure of these solutions differ for spin saturated (single l-shell) and spin unsaturared systems (single j-shell). In the former case the BCS results are checked against an exact calculation.Comment: 19 pages, 5 postscript figure

Effects of soil characteristics on metribuzin dissipation using clay-gel-based formulations

Metribuzin (MTB) is a herbicide widely used for weed control in growing soybeans and other crops and has been identified in many parts of the world as a groundwater contaminant. To prepare controlled-release formulations (CRFs) of MTB, it was entrapped within a sepiolite-gel-based matrix with one of two proportions of clay/herbicide and used as either a gel or powder after freeze-drying. To determine how its persistence in soil is affected by formulation and soil type, MTB was applied as a CRF or commercial formulation (CM) to soils with different properties. MTB dissipation in all soils investigated was reduced when the herbicide was applied as CRFs, especially in the case of sandy soil and the freeze-dried formulations, with DT50 values of 57.5 and 104.1 days, respectively, versus 24.8 days for CM. A positive relationship between degradation rates, bioactivity, and soil pH was found. MTB adsorption-desorption studies on these soils were also performed, and no relationship between adsorption-desorption and the degradation rate of MTB was found, possibly because of the low adsorption capacity of the studied soils. MTB when applied as a CRF remains active longer than CM, avoiding the need to use more frequently herbicide applications.This work was supported by the Spanish Ministry of Education and Science (MEC) through Research Projects AGL 2005-00164, by Junta de Andaluc ́ıa (project P06-FQM-01909), and by AECID (project A/016047/08).Peer Reviewe

Síndrome de Mazabraud: Presentación de un caso clínico y revisión de la literatura

El síndrome de Mazabraud se define como la asociación de una tumoración de partes blandas, el mixoma intramuscular, y un tumor óseo, la displasia fibrosa. Se realiza una revisión bibliográfica de los casos publicados en la literatura, desde que en 1957, Mazabraud acuñó esta asociación como síndrome. El caso clínico corresponde a un varón de 43 años de edad con antecedentes de nódulo frío tiroideo, pigmentación cutánea y lesiones óseas en pelvis y tercio proximal fémur derecho, que acudió a la consulta por presentar una tumoración de partes blandas a nivel del muslo derecho de unos meses de evolución. Tras realizar biopsia de la misma se diagnosticó de mixoma intramuscular. El paciente se intervino quirúrgicamente practicándose resección amplia de la lesión. Hasta la fecha el enfermo no ha presentado recidiva de la lesión de partes blandas, y la displasia ósea no ha sufrido transformación maligna.Mazabraud's síndrome is the association of a soft-tissue tumour, intramuscular myxonma and a bone tumour, fibrous dysplasia. We review the literature since Mazabraud, in 1957 described this syndrome. We report a 43 years male who consulted for a soft-time mass in the right thigh. He also had bone lesions in pelvis and right femur that were diagnosted of fibrous dysplasia. We made a biopsy of soft-tissue tumour and it was diagnosed of intramuscular myxom. The patient was operated and the mass was removed. Till now, there is no recurrence of the myxom and there is no malignant degeneration of the fibrous dysplasia

Depolarization-repolarization synchrony after right ventricular and left bundle branch area pacing

Introduction: Left bundle branch area pacing (LBBAP) has been recently proposed to overcome the limitations associated with right ventricular pacing (RVP) and has been suggested as a new physiological pacing form with high feasibility and safety. A greater difference between QRS complex and T-wave angle directions has been proposed as a marker of abnormal electrical activity in several patient populations, but a comparison between these two pacing modalities has never been performed. The total cosine R to T (TCRT) is an ECG descriptor that accounts for depolarization-repolarization synchrony by measuring the difference between their directions. The purpose of this study was to compare TCRT in patients referred for RVP and LBBAP pacing as anti-bradycardia therapy. Methods: ECG recordings from 134 patients (82 LBBAP, 52 RVP) were classified into two groups, narrow QRS and wide QRS, depending on the patient’s QRS duration prior to implantation. In the post-implantation state, the TCRT index was calculated from a median beat calculated for each patient. Singular value decomposition was applied to the median beat in the eight independent ECG leads (I, II, V1, V2, V3, V4, V5, V6). The QRS complex and T wave loops in a three-dimensional space were determined from the first three components of the decomposition. TCRT was computed as the average of the cosines of the angles between the QRS complex directions and the maximum T wave direction. More positive values corresponded to more synchronized depolarization and repolarization processes while more negative values indicated larger differences in the orientation of the QRS and T wave loops and, therefore, greater dyssynchronization. Results: showed that TCRT took negative values for both techniques, RVP and LBBAP, and both groups, narrow and wide QRS, indicating that pacing generated dyssynchronization between ventricular depolarization and repolarization. Nevertheless, TCRT values for both groups were significantly more negative (p<0.01) for RVP than for LBBAP. We hypothesize that cardiac memory induced by pacing could account for these negative TCRT values. In any case, LBBAP did not increase the difference in the QRS complex and T wave loop orientations as much as RVP. Conclusion: LBBAP induces less dyssynchrony than RVP in the depolarization-repolarization process