Predictability of Plastic Parts Behaviour Made from Rapid Manufacturing

One of the most important issues to resolve in parts manufactured from rapid manufacturing (RM) technologies is to know their behavior working under real conditions. Total quality manufacturing (TQM) is only possible if mechanical properties are well known in the design stage depending on the processing parameters. This work is mainly focused on testing of several samples made with different selective laser sintering (SLS) parameters and technologies. This procedure is the starting point to establish a basis for designing for RM and the standardization of RM testing. The experiments and the analysis of variance (ANOVA) analyzed the effects of several factors on mechanical properties. The SLS technologies were 3DSystem and EOS. The results show which factor has a large effect on the variables and the interaction between them. The conclusions are very useful for developing rules for designing (designing for RM) and creating new standard rules (ISO, AISI, and DIN) for RM materials and parts testing. The ANOVA gives a better knowledge of the effects of these factors and eliminates unimportant parameters.     

Improving moving average trading rules with boosting and statistical learning methods

We present a system for combining the different types of predictions given by a wide category of mechanical trading rules through statistical learning methods (boosting, and several model averaging methods like Bayesian or simple averaging methods). Statistical learning methods supply better out‐of‐sample results than most of the single moving average rules in the NYSE Composite Index from January 1993 to December 2002. Moreover, using a filter to reduce trading frequency, the filtered boosting model produces a technical strategy which, although it is not able to overcome the returns of the buy‐and‐hold (B&H) strategy during rising periods, it does overcome the B&H during falling periods and is able to absorb a considerable part of falls in the market. Copyright © 2008 John Wiley & Sons, Ltd.     

以龙舌兰蔗渣作为还原剂使磁铁矿精矿有效地金属化

The reduction behavior and metallization degree of magnetite concentrate with agave bagasse were investigated in an inert atmosphere. The effects of temperature, biomass content, and residence time on reduction experiments and metallization degree were investigated by X-ray diffraction and scanning electron microscopy. Compared with other types of biomass, agave bagasse had lower contents of nitrogen, sulfur, and ash. X-ray diffraction analysis showed that the metallization degree improved with increasing temperature and biomass content. Complete metallization was achieved at 1100°C for 30 min with 65:35 and 50:50 ratios of the magnetite concentrate to the agave bagasse. These results demonstrate that agave bagasse promotes the efficient metallization of magnetite concentrate without the external addition of a reducing agent. Therefore, this biomass is a technical suitable alternative to replace fossil fuels in steelmaking.     

Effects of insulin hypoglycaemia on the adrenal medulla of the hamster

Résumé Pendant l'hypoglycémie insulinique (4 U/100 g), le hamster maintenu a 19°C présente une augmentation de l'adrénaline et de la noradrénaline plasmatiques, ainsi qu'une réduction de ces deux catécholamines dans les surrénales. Maintenu à 26°C, l'hypoglycémie se produit aussi bien avec 4 U/100 g d'insuline mais il n'y a pas de changements de l'adrénaline et noradrénaline du plasma et des surrénales. Pour obtenir des modifications, il est nécessaire d'augmenter la dose d'insuline à 8 U/100 g. En conclusion, la température extérieure a une influence marquée sur la réponse médullo-surrénale de l'hypoglycémie insulinique.     

On the regulatory properties of a halophilic malic enzyme fromHalobacterium cutirubrum

Summary The NADP-linked malic enzyme fromHalobacterium cutirubrum is strongly inhibited by acetyl-CoA and NADH, and rather weakly inhibited by oxaloacetate and glyoxylate, in the presence of very high KCl concentrations (3,M), considered physiological for the extremely halophilic bacteria.This work was supported by grants from the consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, and the Consejo de Investigaciones de la Universidad Nacional de Rosario. JJC and MCV are members of the Carrera del Investigador Científico of the former and the latter institutions, respectively.     

X-ray microanalysis of animal tissues by means of the field emission-scanning electron microscope

Summary With FESEM the X-ray microanalysis of unstained ultrathin sections (600 Å) free of osmium is possible. Deposits in smooth muscle cells of arteriosclerotic aortae show high calcium-peaks already after 80 sec of measurement. No contamination spots were seen after 11 min of measurement on the same point.     

The role of calcitonin in hypocalcemia in acute experimental pancreatitis

Summary Experimental pancreatitis in rats was accompanied by hypocalcemia. Thyroidectomy did not abolish the fall in serum calcium observed in intact animals during pancreatitis. Data presented in our study suggest that the thyroid gland and calcitonin are not important factors in causing the hypocalcemia observed in rats.