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

Effect of antimony on the eutectic reaction of heavy section spheroidal graphite castings

There is a strong demand for heavy section castings made of spheroidal graphite with a fully ferritic matrix, e.g. for manufacturing hubs for windmills. Such castings with slow solidification process are prone to graphite degeneration that leads to a dramatic decrease of the mechanical properties of the cast parts. Chunky graphite is certainly the most difficult case of graphite degeneracy, though it has long been known that the limited and controlled addition of antimony may help eliminate it. The drawback of this remedy is that too large Sb additions lead to other forms of degenerate graphite, and also that antimony is a pearlite promoter. As part of an investigation aimed at mastering low level additions to cast iron melts before casting, solidification of large blocks with or without Sb added was followed by thermal analysis. Comparison of the cooling curves and of the microstructures of these different castings gives suggestions to understand the controlling nucleation and growth mechanisms for chunky graphite cells

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

Chemometric analysis of minerals and trace elements in raw cow milk from the Community of Navarra

The concentrations of protein, fat, five minerals (Na, K, P, Ca and Mg) and nine trace elements (Fe, Zn, Cu, Mn, Se, Al, Cd, Cr and Pb) have been determined in 347 samples of raw cow milk from the community of Navarra, north Spain, using infrared analysis, atomic absorption spectrometry (flame and electrothermal atomisation) and inductively coupled plasma atomic emission spectroscopy. A preliminary chemometric study with the use of pattern recognition methods was carried out in order to characterise, classify and distinguish the different collected samples on the basis of their contents. Principal component analysis (PCA) has permitted the reduction of 16 variables to five principal components which interpret reasonably well the correlations of these studied variables. These variable associations may be attributed to intrinsic (lactogenesis) and other extrinsic factors, such as seasonal variation, animal feeding or geographical situation. Changes in these contents during different seasons were also assessed and consistently interpreted. Linear discriminant analysis (LDA) was used to explore cow milk samples, classifying according to season or geographical location, providing complementary information to PCA. This work shows that PCA and LDA are useful chemometric tools for the multivariate characterisation of raw cows’ milk

Conocimientos actuales y perspectivas de investigación de elementos traza en la nutrición infantil: parte I. Situación actual de la alimentación infantil

La nutrición infantil ha experimentado una creciente evolución en función de los estudios de investigación desarrollados y los diferentes criterios adoptados para establecer unas recomendaciones que satisfagan plenamente las necesidades fisiológicas y demandas nutricionales del neonato. La normativa de composición de las fórmulas ha sido dictadas por la Sociedad Europea de Gastroenterología y Nutrición Pediátrica (ESPGAN) y la Academia Americana de Pediatría (AAP). Recientemente el Panel de Expertos del Life Sciences Resarch Office (LSRO) de la American Society for Nutritional Sciences (ASNS) ha sido establecido las últimas disposiciones en relación a los niveles recomendados de diferentes nutrientes en las formulas infantiles de manera que su cumplimiento asegure y proporcione, por si mismas, la única fuente de alimento de los lactantes a término durante su primer año de vida. No hay duda de que la lactancia natural es la más adecuada para el recién nacido y que es preferible a cualquier otro tipo de alimentación infantil. No obstante, el empleo de las fórmulas infantiles se hace imprescindible en aquellos casos en que no sea posible la alimentación del lactante con leche materna. El modelo de lactancia natural en España es similar al de los países del área industrializada del mundo, aunque su duración es sensiblemente inferior a la descrita para otros países del área europea, se abandona masivamente a lo largo del primer semestre de vida. No sólo se debe considerar la leche materna bajo aspectos analíticos cuantitativos en cuanto a su contenido en nutrientes esenciales, sino también es necesario que las fórmulas infantiles proporcionen una fuente de micronutrientes biodisponibles y, en este sentido, todavía hoy los conocimientos sobre ingesta, requerimientos, biodisponibilidad e intervalos de tolerancia de gran parte de los oligoelementos, con respecto a su influencia en el desarrollo infantil, son todavía limitados e insuficientes

Conocimientos actuales y perspectivas de investigación de elementos traza en la nutrición infantil: parte II. Niveles de concentración, ingesta dietética y requerimientos de la alimentación infantil.

La leche materna sirve de referencia en cuanto al contenido de micronutrientes, ya que, por razones de ética, dichos datos no pueden ser obtenidos de lactantes humanos en buen estado de salud. La concentración de los distintos oligoelementos en la leche materna va disminuyendo a medida que transcurre el tiempo de lactancia, por lo que llegado el cuarto mes, si el niño es exclusivamente alimentado con leche materna y pertenece a un grupo particularmente predispuesto (bajos depósitos orgánicos, incremento de las necesidades, aumento de pérdidas, reducción de la absorción intestinal), pueden desarrollarse cuadros de deficiencias nutricionales dependientes del oligoelemento deficitario. El presente trabajo recoge los contenidos de los principales elementos traza esnciales (hierro, zinc, cobre, manganeso y selenio) y aquellos potencialmente tóxicos (aluminio, plomo y cadmio), hallados en las fórmulas infantiles en una amplia revisión bibliográfica. Los requerimientos nutricionales de elementos traza son específicos de cada neonato. Las recomendaciones dietéticas deben establecerse de manera que observen pautas bastante generosas, considerando la amplia variación interindividual, para que se cubra las necesidades de la mayor parte de la población neonatal. Atendiendo a esta consideración, el Comité conjunto de la OMS/FAO/IAEA incorpora dos nuevos conceptos, no considerados anteriormente, sobre requerimientos de elementos traza: requerimientos basales y normalizados. Con este estudio se ha dado un gran paso en el establecimiento de recomendaciones dietéticas para lactantes, aunque no se debe perder de vista que esta estimación de ingesta dietética no es suficiente en si misma; siendo necesaria una mayor investigación en los balances metabólicos de elementos traza en el organismo neonatal y se requiere de un mayor conocimiento de las formas químicas biodisponibles adecuadas a la nutrición pediátrica

Conocimientos actuales y perspectivas de investigación de elementos traza en la nutrición infantil: parte III. Biodisponibilidad y necesidades de investigación futura

La alimentación de los lactantes mediante las fórmulas lácteas no suplementadas, durante periodos de tiempo prolongados, presenta el riesgo del desarrollo de deficiencias nutricionales de diversos oligoelementos; en contraste, los lactantes alimentados con leche materna rara vez presentan alguna deficiencia mineral Puesto que la concentración de estos oligoelementos en la leche humana con frecuencia es más baja o igual que aquella de las fórmulas lácteas, incluso sin suplementar, está implicada claramente una más alta biodisponibilidad de estos elementos desde la leche humana. Es conveniente la comparación entre la leche humana y la de vaca, ya que esta última va a ser, en definitiva, materia prima principal de muchas fórmulas infantiles. Ello permite utilizar sus valores de concentración con fines comparativos, en cuanto a la cantidad de elementos traza suministrada, y el establecimiento de su distinta distribución entre los componentes mayoritarios. Este trabajo presenta una amplia revisión de los principales estudios de biodisponibilidad de elementos traza en leche humana, de vaca y fórmulas infantiles. Dado que la absorción y posterior utilización de los elementos traza por el neonato, no solo depende del contenido total en la fórmula infantil, sino de la forma química en la cual se encuentra y los compuestos en los que se integran, parece oportuno caracterizar, no solo los componentes principales de la fórmula infantil, sino los micronutrientes para encontrar las formas químicas más adecuadas y de mejor biodisponibiliad, mediante estudios de especiación, para evitar las posibles interacciones debido a las altas concentraciones inorgánicas añadidas, con la finalidad de asemejar aún más si cabe, al estándar de la alimentación infantil, la leche materna

Digging into acceptor splice site prediction : an iterative feature selection approach

Feature selection techniques are often used to reduce data dimensionality, increase classification performance, and gain insight into the processes that generated the data. In this paper, we describe an iterative procedure of feature selection and feature construction steps, improving the classification of acceptor splice sites, an important subtask of gene prediction. We show that acceptor prediction can benefit from feature selection, and describe how feature selection techniques can be used to gain new insights in the classification of acceptor sites. This is illustrated by the identification of a new, biologically motivated feature: the AG-scanning feature. The results described in this paper contribute both to the domain of gene prediction, and to research in feature selection techniques, describing a new wrapper based feature weighting method that aids in knowledge discovery when dealing with complex datasets

Conditional Born-Oppenheimer dynamics: quantum dynamics simulations for the model porphine

We report a new theoretical approach to solve adiabatic quantum molecular dynamics halfway between wave function and trajectory-based methods. The evolution of a N- body nuclear wave function moving on a 3N-dimensional Born−Oppenheimer potential-energy hyper-surface is rewritten in terms of single-nuclei wave functions evolving nonunitarily on a 3-dimensional potential-energy surface that depends parametrically on the configuration of an ensemble of generally defined trajectories. The scheme is exact and, together with the use of trajectory-based statistical techniques, can be exploited to circumvent the calculation and storage of many-body quantities (e.g., wave function and potential-energy surface) whose size scales exponentially with the number of nuclear degrees of freedom. As a proof of concept, we present numerical simulations of a 2-dimensional model porphine where switching from concerted to sequential double proton transfer (and back) is induced quantum mechanicall

Connectivity, neutral theories and the assessment of species vulnerability to global change in temperate estuaries

One of the main adaptation strategies to global change scenarios, aiming to preserve ecosystem functioning and biodiversity, is to maximise ecosystem resilience. The resilience of a species metapopulation can be improved by facilitating connectivity between local populations, which will prevent demographic stochasticity and inbreeding. The objective of this investigation is to estimate the degree of connectivity among estuarine species along the north-eastern Iberian coast, in order to assess community vulnerability to global change scenarios. To address this objective, two connectivity proxy types have been used based upon genetic and ecological drift processes: 1) DNA markers for the bivalve cockle (Cerastoderma edule) and seagrass Zostera noltei, and 2) the decrease in the number of species shared between two sites with geographic distance; neutral biodiversity theory predicts that dispersal limitation modulates this decrease, and this has been explored in estuarine plants and macroinvertebrates. Results indicate dispersal limitation for both saltmarsh plants and seagrass beds community and Z. noltei populations; this suggests they are especially vulnerable to expected climate changes on their habitats. In contrast, unstructured spatial pattern found in macroinvertebrate communities and in C. edule genetic populations in the area suggests that estuarine soft-bottom macroinvertebrates with planktonic larval dispersal strategies may have a high resilience capacity to moderate changes within their habitats. Our findings can help environmental managers to prioritise the most vulnerable species and habitats to be restored