PBO Fibres: from saliling design towards architectural performance

p. 3013-3023PBO fibres, also called "high-performance" polymer fibres, are a group of materials known as "rigid rods". Through this work it is pretended to make some considerations about the use of these new generation fibres. Poly (p-phenylene-2.6-benzobisoxazole)(PBO) is rigid-rod isotropic crystal polymer. PBO fibre is a high performance fibre developed by TOYOBO (Japan) PBO fibre is quite flexible and has very soft handling, in spite of its extremely high mechanical properties. Over the past ten years Future Fibres Company has pioneered the use of PBO for yacht rigging and has proven it to provide remarkable performance and longevity. Their method of producing these PBO cables delivers the lightest, smallest cables available on the market today. The PBO cable is formed by combining the incredible properties of PBO (poly(p-phenylene-2,6- benzobisoxazole)) fibre with the simple yet undeniably reliable process of continuous winding. A PBO cable is dry fibre tightly compacted and does not rely on a resin matrix that, if impacted, can be compromised. The cover of the cable is a vital component and whilst PBO is an excellent material for yacht rigging purposes, due to its extreme strength, low elongation and general robustness it must be protected from sunlight and seawater. Future Fibres has perfected its cover design that comprises a consolidating film, environmental protection layer and a customizable braided cover that can be tailored to suit any specific application. PBO has great potential to be used in construction or rehabilitation applications. At the same time the fibres, following further testing, would open up several design opportunities for high quality architectural projects.Gough, CE.; Pobo Blasco, M.; Ruiz Checa, JR. (2009). PBO Fibres: from saliling design towards architectural performance. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/670

Structural changes at the semiconductor-insulator phase transition in the single layered La0.5Sr1.5MnO4 perovskite

The semiconductor-insulator phase transition of the single-layer manganite La0.5Sr1.5MnO4 has been studied by means of high resolution synchrotron x-ray powder diffraction and resonant x-ray scattering at the Mn K edge. We conclude that a concomitant structural transition from tetragonal I4/mmm to orthorhombic Cmcm phases drives this electronic transition. A detailed symmetry-mode analysis reveals that condensation of three soft modes -Delta_2(B2u), X1+(B2u) and X1+(A)- acting on the oxygen atoms accounts for the structural transformation. The Delta_2 mode leads to a pseudo Jahn-Teller distortion (in the orthorhombic bc-plane only) on one Mn site (Mn1) whereas the two X1+ modes produce an overall contraction of the other Mn site (Mn2) and expansion of the Mn1 one. The X1+ modes are responsible for the tetragonal superlattice (1/2,1/2,0)-type reflections in agreement with a checkerboard ordering of two different Mn sites. A strong enhancement of the scattered intensity has been observed for these superlattice reflections close to the Mn K edge, which could be ascribed to some degree of charge disproportion between the two Mn sites of about 0.15 electrons. We also found that the local geometrical anisotropy of the Mn1 atoms and its ordering originated by the condensed Delta_2 mode alone perfectly explains the resonant scattering of forbidden (1/4,1/4,0)-type reflections without invoking any orbital ordering.Comment: 3 tables and 10 figures; accepted in Phys. Rev.

Evaluación de un sistema silvopastoril sobre vinalares en Formosa, Argentina

El vinal (Prosopis ruscifolia), afecta campos ganaderos y cultivos abandonados. Los métodos tradicionales para eliminarlo son costosos e ineficientes. Se analizó la factibilidad económica del modelo silvopastoril alternativo, el mismo consta de 10 módulos de 3 ha. que se instalan a razón de 1 módulo por año. Se realizan intervenciones forestales de saneamiento y aprovechamiento quinquenales, el componente ganadero se mejora con enriqueciendo del estrato herbáceo y apotreramientos. Estas intervenciones logran mejorar considerablemente la capacidad productiva del campo. Analizando el flujo de caja durante 20 años, se observa que las mejoras representan un incremento del ingreso predial de 9000 dólares/ año. En la actualidad el modelo es implementado por 40 productores con distintas situaciones socioproductivas en la provincia de Formosa (Argentina)

Chromium content in different kinds of spanish infant formuale and estimation of dietary intake by infants fed on reconstituted powder formulae

The essentiality of chromium in humans is well documented. Trivalent chromium, main chemistry form found in foods, is essential for maintaining normal glucose metabolism. Because of analytical difficulties, several literature reports of chromium content of foods, especially for the lower levels, show large variability and they should be interpreted with caution for a valid interpretation of reliable results. A Zeeman background correction transversely-heated graphite furnace atomic absorption spectrometry was used to determine the chromium content of 104 different infant formulae (cow’s milk and soy protein based) marked in Spain following an acid attack sample preparation procedure in a closed, pressurized and microwave digestion unit. Mean and range chromium values, regarding types and main protein-based infant formulae are presented. Additionally, the influence of the type of container used, the impact of industrial process from different manufacturers and the physical state (powder and liquid formulae) on chromium levels is also discussed. In general, the infant formulae contain a higher chromium concentration than that found in human milk (reference range: 0.20 – 8.18 g l-1), particularly in case of hypoallergenic (18.16 ± 7.89 g l-1), lactose-free (11.37 ± 3.07 g l-1), preterm (11.48 ± 3.15 g l-1) and soya (10.43 ± 4.05 g l-1) formulae. The maximum theoretical estimated intake of infant fed on studied formulae was lower than the upper limit safety for trivalent chromium of 1 mg kg-1 (14 g Kg-1 b.w. day-1) recommended by the experts of Council for Responsible Nutrition (CRN ULS, 2004), amounting to about 10 %, 15-18 % and 26 % for standard (adapted and follow-up) and toddler; soya, lactose-free and preterm; and hypoallergenic formulae, respectively. Therefore, manufacturers are called for continued effort to routinely monitor chromium levels, mainly for specialised and preterm formulae, and at the same time, might consider the inclusion of labelling value for chromium at least in these complex formulations

Optimization of a Slurry Dispersion Method for Minerals and Trace Elements Analysis in Infant Formulae by ICP OES and FAAS

Infant formula developed by manufacturers requires a rigorous control of composition, particularly those elements added routinely in an attempt to mimic the mineral composition of human milk. A total of 97 different types of powdered infant formulae (preterm, adapted starter, adapted follow-up, toddler, specialised and soy based formulae) commercially available in Spain were studied. It is noteworthy great differences in mineral (Ca, P, Mg) and trace element (Zn, Fe, Cu, Mn) contents found between analysed and listed in label information. The development of a fast, simple and direct slurry method for the determination of these essential micronutrients in infant formula by inductively coupled plasma optical emission spectrometry (ICP OES) and flame atomic absorption spectrometry (FAAS) was performed in order to help in quality control tasks. Infant formula samples were solubilised using different amounts of several different solvents. An addition of 250 L of a solution 10 % tetramethylammonium hydroxide and 25 % ammonium hydroxide were required for the accurate quantification of Ca and P, Mg, Zn, Fe, Cu and Mn, respectively. The standard reference material 1549 non-fat milk powder was solubilised to compare the validity of assayed methodology following slurry nebulisation and traditional microwave-assisted acid digestion method. Good agreement of the analytical results by both ICP OES and FAAS, with the certified values was obtained. Method performance parameters (accuracy, precision and methodological detection limits) were determined for studied elements to check the quality and usefulness of the optimised slurry method. The analytical procedure was applied successfully to the analysis of a representative group of infant formulae. Levels of analysed elements were graphically represented, showing an acceptable comparability between slurry and acid-mineralisation method set by linear correlation coefficients and slopes close to the unit. The described simple and slurry method is appropriate, as an attractive alternative, for routine control analysis of added essential elements in infant formulae regardless of predominant protein type used in manufacture

Evaluación de un sistema silvopastoril sobre vinalares en Formosa, Argentina

El vinal (Prosopis ruscifolia), afecta campos ganaderos y cultivos abandonados. Los métodos tradicionales para eliminarlo son costosos e ineficientes. Se analizó la factibilidad económica del modelo silvopastoril alternativo, el mismo consta de 10 módulos de 3 ha. que se instalan a razón de 1 módulo por año. Se realizan intervenciones forestales de saneamiento y aprovechamiento quinquenales, el componente ganadero se mejora con enriqueciendo del estrato herbáceo y apotreramientos. Estas intervenciones logran mejorar considerablemente la capacidad productiva del campo. Analizando el flujo de caja durante 20 años, se observa que las mejoras representan un incremento del ingreso predial de 9000 $/año. En la actualidad el modelo es implementado por 40 productores con distintas situaciones socioproductivas en la provincia de Formosa (Argentina).

Ultrasonic estimates of fat thickness and longissimus dorsi muscle depth for predicting carcass composition of live Aragon lambs

Six ultrasonic fat and muscle depth measurements, taken on the left and the right side of the fourth lumbar vertebra and third stemebra of the breast bone, were related to carcass composition to determine the accuracy of these measurements for predicting carcass compositon of live Aragdn lambs (Temasco) . Live weight alone accounted for 21, 19,26, 18 and 47% of total variation of muscle, bone plus remainder, total fat, and subcutaneous and intermuscular fat, respectively. Addition of ultrasonic fat depth measurement on the right side of the lumbar region accounted for a further 18,31,33 and 36% of muscle, bone plus remainder, total carcass fat and subcutaneous fat, respectively. Addition of the same measurement taken on the left side accounted for a further 15% of intermuscular fat. Live weight alone accounted for only 4% of the total variation of kidney and pelvic fat, but the addition of ultrasonic fat depth measurement on breast bone accounted for a further 26% of the variation of this fat depot. The accuracy of prediction of carcass composition on live animals could be improved by the addition of ultrasonic fat measurements.Un total de 6 mesures d'épaisseur du gras et du muscle, réalisées en utilisant des ultrasons sur la 4ème vertèbre lombaire et la 3ème sternèbre sternale, ont été rapportées à la composition de la carcasse, en ayant comme objetif d'étudier l'exactitude de ces mesures en tant qu'élément de prédiction de la composition de la carcasse d'agneaux vivants producteurs du ‘Ternasco d'Aragón’. Le poids vif à lui seul a expliqué 21, 19, 26, 18 et 47% de la variation totale du muscle, de l'os plus les déchets, du gras total et du gras souscutané et intermusculaire, respectivement. L'addition des mesures d'épaisseur du gras (mesure C) réalisées par ultrasons sur le côté droit de la région lombaire, ont augmenté de 18, 31, 33 et 36% la précision de l'estimation de la variation totale du muscle, de l'os plus déchets, du gras total et sous-coutané de la carcasse, respectivement. L'addition de la même mesure réalisée sur le côté gauche a augmenté de 15% la précision de l'estimation de la variation totale du gras intermusculaire. Cependant, le poids vif n'a expliqué que 4% de la variation totale du gras pelvico-rénal, mais l'addition de la mesure d'épaisseur du gras sternal total, réalisée aux ultrasons, a augmenté de 26% la précision de l'estimation de la variation de ce dépôt adipeux. La précision de la prédiction de la composition de la carcasse sur l'animal vivant pourrait augmenter par l'addition de mesures de l'épaisseur du gras réalisées aux ultrasons.Un total de 6 medidas de espesor de grasa y músculo realizadas mediante la utilización de ultrasonidos sobre la 4a vertebra lumbar y la 3a esternebra del esternón fueron relacionadas con la composición de la canal, con el principal objetivo de estudiar la exactitud de estas medidas como predictoras de la composición de la canal de corderos vivos productores de ‘Ternasco de Aragón’. El peso vivo solo explicó el 21, 19, 26, 18 y 47% de la variación total del músculo, hueso más desechos, grasa total y grasa subcutanea e intermuscular respectivamente. La adición de las medidas de espesor de grasa (medida C) realizadas con ultrasonidos sobre el lado derecho de la región lumbar, incrementaron un 18, 31, 33 y 36% la precisión de la estimacón de la variación total del músculo, hueso más desechos, grasa total y subcutánea de la canal respectivamente. Y la adición de la misma medida realizada sobre el lado izquierdo incrementó un 15% la precisión en la estimación de la variación total de grasa intermuscular. Sin embargo el peso vivo solo explicó el 4% de la variación total de grasa pelvico-renal, pero la adición de la medida de espesor de grasa total del esternón realizada con untrasonidos, incrementó un 26% la precisión de la estimación de la variación de este depósito adiposo. La precisión de la predicción de la composición de la canal en el animal vivo podría ser incrementada con la adición de medidas del espesor de grasa realizadas con ultrasonidos