Regional calibration of erosion radiotracers (210Pb and 137Cs): atmospheric fluxes to soils (northern Spain)

Inventories of radionuclides commonly used to study environmental processes, especially in erosion research, were determined in soil cores from two distant river basins in northern Spain. Results showed that 210Pb atmospheric fluxes correlate very well with mean annual rainfall across the region, and this is also the case for 137Cs inventories but only on the basin scale. Therefore we suggest that 210Pb is a better candidate as a radiotracer for soil erosion studies. In this region, the equation 210Pb flux (Bq m(-2) yr(-1)) = (0.19 +/- 0.02) x rainfall (mm yr(-1)) - (24 +/- 17) can be used as a calibration to estimate input 210Pb fluxes, a key parameter in soil erosion studies and models, when mean annual rainfall is known.     

Modeling of the tensile moduli of mechanical,thermomechanical, and chemi‐thermomechanical pulps from orange tree pruning

Stiffness is one of the most relevant properties of composite materials. Although fiberglass has been traditionally used as reinforcement, natural fibers are seen as possible replacements due to concerns for environmental protection. In this work fibers from orange tree prunings were prepared and converted into mechanical, thermomechanical and chemi‐thermomechanical pulps, to be used as reinforcement for polypropylene. Polypropylene composite materials with 20–50% of reinforcing fibers were prepared and mechanically characterized. The intrinsic Young's modulus of the fibers was back calculated by means of the Hirsch model. The moduli were also obtained by Halpin‐Tsai equations with Tsai‐Pagano methods and then compared to establish the influence of the aspect ratio. Finally, a fiber tensile modulus factor was defined in order to characterize the contribution of the fibers to the Young's moduli of the composites. POLYM. COMPOS., 34:1840–1846, 2013. © 2013 Society of Plastics Engineers     

IRT-Related Factor Analytic Procedures for Testing the Equivalence of Paper-and-Pencil and Internet-Administered Questionnaires.

This article describes a general item response theory-based factor analytic procedure that allows assessment of the equivalence between 2 administrative modes of a questionnaire: paper and pencil, and Internet based. The theoretical relations between the present procedure and other methods used in previous empirical research are shown, and the advantages of the procedure are discussed. An empirical application based on 2 personality questionnaires is given, and the results are compared with the results of using traditional procedures for assessing equivalence. The substantive implications of the results, as well as suggestions for further research and methodology, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of 12, 24 and 72 hours fasting in thermogenic parameters of rat brown adipose tissue mitochondrial subpopulations

The aim of the present work was to study the effects of various durations of fasting (12, 24 and 72 hours) on brown adipose tissue (BAT) thermogenic parameters--cytrochrome-c-oxidase (COX) activity, GDP-binding activity and uncoupling protein (UCP1) content--and also on morphological features of different mitochondrial subpopulations, obtained by differential centrifugation--M1 (1000 g), M3 (3000 g) and M15 (15,000 g) fractions. The mitochondrial subpopulations showed morphological differences and a different distribution of UCP1 levels and of GDP-binding in all experimental groups. Starvation induced a decrease in the average size for all mitochondrial subtypes. The main changes induced by fasting in thermogenic parameters were observed in the M15 subtype. After the first 24h of starvation, there was a significant decrease of UCP1 levels only in the lightest mitochondrial subpopulation. However, the 72h fasted situation reflected a tendency to increase UCP1 content and UCP1/COX ratio together with a significant decrease of GDP-binding/UCP1 ratio, thus indicating more masked GDP-binding sites. Important fasting-induced changes in both morphological and biochemical parameters in BAT mitochondrial subtypes reflect their role in the physiological response of BAT to starvation.     

WeMOI and NAOi influence on major avalanche activity in the Eastern Pyrenees

Major avalanche episodes registered in the Eastern Pyrenees (north-eastern Iberian Peninsula) are correlated with both the North Atlantic Oscillation (NAO) and the Western Mediterranean Oscillation (WeMO). The NAO is one of the most important and recurrent patterns of atmospheric circulation variability in the Northern Hemisphere and affects the behaviour of surface temperatures and precipitation in Western Europe. The Western Mediterranean Oscillation index (WeMOi) controls intense precipitation in the eastern part of the Iberian Peninsula. The link between both indices and major avalanche activity is undertaken by applying a cumulative index. A link between avalanche activity and the NAO has been found in Iceland, but it has not been detected in areas closer to the Pyrenees, such as the French Alps. This paper examines the linkage to the NAO in an area further from the centres of the dipole than is the case for Iceland. Results show a significant negative correlation between major avalanche activity in the Eastern Pyrenees and both NAO index (NAOi) and WeMOi, which is even higher with the cumulative NAOi (CNI) and the cumulative WeMOi (CWI). The cumulative index reflects the cumulative effect of snow accumulation in the avalanche starting zones as precipitation is affected by the variations of NAOi and WeMOi. Consequently, the correlation is negative since it has been demonstrated that increased precipitation in the Eastern Pyrenees is linked to negative values of both low frequency patterns. Nevertheless, results from the diverse avalanche forecasting regions in the Eastern Pyrenees suggest a different response of avalanche activity to both indices, confirming the Pyrenees as a complex snow-climate boundary. Lastly, possible changes in avalanche activity in the coming decades may be suggested by the NAO evolution associated with global warming scenarios that are foreseen and the present interannual trend of the WeMOi.     

Synthesis and properties of poly(hexamethylene terephthalate)/multiwall carbon nanotubes nanocomposites

Poly(hexamethylene terephthalate) (PHT)/carbon nanotubes (CNT) nanocomposites containing 1% and 3% (w/w) of filler were prepared by two procedures: in situ ring-opening polymerization of hexamethylene terephthalate cyclic oligomers in the presence of CNT and melt blending of PHT/CNT mixtures. Arc discharge multiwalled carbon nanotubes, both pristine (MWCNT) and hydroxyl functionalized (MWCNT-OH), were used. The objective was to evaluate the effect of preparation procedure, nanotube side-wall functionalization and amount of nanotube loaded on properties of PHT. All nanocomposites showed an efficient distribution of the carbon nanotubes within the PHT matrix but interfacial adhesion and reinforcement effect was dependent on both functionalization and nanotubes loading. Significant differences in thermal stability and mechanical properties ascribable to functionalization and processing were observed among the prepared nanocomposites. All the prepared nanocomposites showed enhanced crystallizability due to CNT nucleating effects although changes in melting and glass transition temperatures were not significant.     

Process and recyclability analyses of innovative bio‐composite for tray

The originality of the present study is to give complete and pragmatic information associated with the preparation of a totally bio‐based composite. It covers the most relevant investigations from analyses of the fibres used as reinforcing elements to the final product acquisition and its recyclability analyses. This study is destined for packaging areas. It demonstrates the three‐dimensional formation processes with these new kinds of bio‐composites, as well as the recyclable features related to the prepared materials. Thus, several processing parameters were studied and a final tray was prepared. The addition of the fibres gives rise to an increase of the tray stiffness, when a flexible biopolymer is used as a matrix. The prepared bio‐composites were recycled several times (10 recycling cycles) and found that they maintain their most relevant characteristics. Thus, such bio‐composites can be reused several times. All these data, including a prototype sample prepared as a demonstrator, support the innovative and sustainable character of the packaging materials described. Copyright © 2010 John Wiley & Sons, Ltd.