Axially loaded RC columns strengthened by steel caging. Finite element modelling

Reinforced concrete (RC) columns in buildings often need strengthening either due to defects in the columns themselves, having to support higher loads than those foreseen in the initial design of the structure, or as the result of ageing or accidental damage. The use of steel caging for this purpose is now a common practice in many countries throughout the world. Based on the results of an experimental study, this paper presents a parametric study using finite element models carried out with the aim of analysing the behaviour of RC columns strengthened by steel caging. The results of the study are used to analyse the influence that various parameters have on the behaviour of the strengthened column (size of the angles, the yield stress of the steel of the cage, the compressive strength of the concrete in the column, the size of the strips, the addition of an extra strip at the ends of the cage, the friction coefficient between the layer of mortar and the steel of the cage). The results obtained from the parametric study allow a series of guidelines to be established.     

A technique for studying the 3-dimensional shape of corrosion pits

A technique has been developed for studying the 3-dimensional shapes of corrosion pits. The technique involved the preparation of epoxy replicas of pits and has been demonstrated in preliminary studies of pitting corrosion in a 2024-T3 aluminum alloys. The replicas are shown to be faithful reproductions of the corroded surface, reflecting all of the key features of small and large corrosion pits. They provide a 3-dimensional perspective that is heretofore missing from surface observations and serial sectioning techniques, and can aid in the quantitative assessments of the kinetics and the mechanistic understanding of pitting corrosion. Measurement techniques are being developed to capture the key geometric information from the replicas. Further studies of the mechanism and kinetics of pitting corrosion in the high-strength aluminum alloys using these techniques are in progress, and will be reported.     

Information about the diagnosis: a subjective experience of patients with multiple sclerosis and rheumatoid arthritis

INTRODUCTION: It may be difficult to determine the adequate mement, the information content and the most convenient person to inform patients with chronic, incurable disorders with uncertain prognosis as sclerosis multiple (MS). MATERIAL AND METHODS: To gain information on how these aspects had been carried-out and the extent to which patients felt satisfied, we studied 60 definite MS ambulatory patients by means of a semistructured questionnaire attending a hospital-based MS unit. The results were compared with those from 40 patients with rheumatoid arthritis (RA), a chronic disabling disorder of the locomotor system with variable course, examined in a similar way. RESULTS: In the vast majority of patients (81.7 and 82.9%, respectively) in both groups the diagnosis had been delivered by a specialist, a point on which most patients agreed upon as convenient. However, most MS patients (78.4%) and nearly all of those with RA (97.6%) should have desired to receive information on their diagnosis as soon as this might had been firmly established. Though more than half the patients (61.7 of MS and 56.1% of RA) admitted to have developed depressive symptoms following information on their diagnosis, a majority expressed their desire to have been informed early about 'all the truth' regarding their prognosis (78.4 and 87.8%, respectively). CONCLUSIONS: Though data from this study should be taken with caution when applied to MS patients shortly after experiencing their first symptoms, and it is therefore unwise to give rigid rules, the vast majority of MS patients express the desire to receive early, accurate, and individualized information on their diagnosis provided by a competent specialist.     

Morphological features of neurons containing calcium-binding proteins in the human striatum

An immunohistochemical approach was used to characterize the morphological phenotype of neurons containing the calcium-binding proteins calretinin (CR), parvalbumin (PV), or calbindin-D28k (CB) in the normal human striatum. The protein CR occurs in at least four morphologically distinct types of neurons. Apart from the numerous medium-sized aspiny interneurons and the less abundant giant aspiny interneurons, CR also labels some medium-sized spiny neurons morphologically identical to striatal projection neurons. This finding indicates that CR is not only confined to striatal interneurons but also may be involved in the function of certain projection neurons. Some small and peculiar bushy-like aspiny neurons also are enriched with CR. These neurons could correspond to the dwarf or neurogliform neurons first described by Ramón y Cajal (1911). Three types of PV-immunoreactive striatal neurons can be visualized in the human striatum: 1) the common medium-sized aspiny leptodendritic neurons, 2) some smaller and profusely arborized aspiny neurons, and 3) a few large and intensely stained neurons with conspicuously beaded and poorly branched dendrites. The protein CB labels virtually all medium-sized spiny projection neurons located in the striatal matrix but also identifies a small subset of large and more intensely immunostained aspiny neurons. The latter finding indicates that CB is not entirely confined to striatal projection neurons but also may play a role in local circuit neurons. These normative data should help our understanding of the chemical anatomy of the human striatum in both health and disease.     

Sorption of selenium(IV) and selenium(VI) onto natural iron oxides: goethite and hematite

Selenium is a toxic element with a relatively high mobility in the natural waters. Iron oxy-hydroxides might play an important role in the migration of this element as well as on its removal from contaminated water. In this work we study the interaction of Se(IV), and Se(VI) with natural iron oxides hematite and goethite through two series of batch experiments at room temperature. In the first series, sorption as a function of initial selenium concentration is studied and the results have been fitted with Langmuir isotherms. In a second series of experiments, sorption is studied as a function of pH, being the main trend an increase of the sorption at acidic pH. The variation of the sorption with pH has been modelled with a triple layer surface complexation model and using the FITEQL program. The experimental data have been modelled considering for the Se(IV) the formation of the FeOSe(O)O(-) complex onto the hematite surface, and a mixture of FeOSe(O)O(-), and FeOSe(O)OH onto the goethite surface. For Se(VI) the surface complex considered is FeOH(2)(+)-SeO(4)(2-) on both goethite and hematite.     

Risk minimisation of FGD gypsum leachates by incorporation of aluminium sulphate

The incorporation of aluminium sulphate to (flue gas desulphurisation) FGD gypsum before its disposal was investigated as a way to minimise the risk supposed by the high fluoride content of its leachates. Using a bath method the kinetic and equilibrium processes of fluoride removal by aluminium sulphate were studied at fluoride/aluminium molar concentration (F/Al) ratios in the range 1.75 10(-2)-1.75 under the pH conditions (about 6.5) of FGD gypsum leachates. It was found that fluoride removal was a very fast process at any of the (F/Al) ratios subject of study, with equilibrium attained within the first 15 min of interaction. High decreases in solution fluoride concentrations (50-80%) were found at the equilibrium state. The use of aluminium sulphate in the stabilization of FGD gypsum proved to greatly decrease its fluoride leachable content (in the range 20-90% for aluminium sulphate doses of 0.1-5%, as determined by the European standard EN 12457-4). Such fluoride leaching minimisation assures the characterization of this by-product as a waste acceptable at landfills for non-hazardous wastes according to the Council Decision 2003/33/EC on waste disposal. Furthermore, as derived from column leaching studies, the proposed stabilization system showed to be highly effective in simulated conditions of disposal, displaying fluoride leaching reduction values about 55 and 80% for aluminium sulphate added amounts of 1 and 2%, respectively.     

Mineral content in legumes and nuts: contribution to the Spanish dietary intake

We evaluated the levels of essential elements as Cu, Cr, Fe and Zn, and toxic elements as Al, Ni, Pb and Cd in a total of 40 samples of different legumes and 56 samples of different nuts, that are widely consumed in Spain. These elements were determined in the samples mineralized with HNO(3) and V(2)O(5), using electrothermal atomic absorption spectrometry (ETAAS) as the analytical technique. Reliability of the procedure was checked by analysis of a certified reference material. No matrix effects were observed and aqueous standard solutions were used for calibration. In legumes, the levels ranged from 1.5-5.0 microg Cu/g, 0.05-0.60 microg Cr/g, 18.8-82.4 microg Fe/g, 32.6-70.2 microg Zn/g, 2.7-45.8 microg Al/g, 0.02-0.35 microg Ni/g, 0.32-0.70 microg Pb/g and not detectable-0.018 microg Cd/g. In nuts, the levels ranged from 4.0-25.6 microg Cu/g, 0.25-1.05 microg Cr/g, 7.3-75.6 microg Fe/g, 25.6-69.0 microg Zn/g, 1.2-20.1 microg Al/g, 0.10-0.64 microg Ni/g, 0.14-0.39 microg Pb/g, and not detectable-0.018 microg Cd/g. A direct statistical correlation between Cu-Cr, Zn-Al and Cr-Ni (P<0.05), and Al-Pb (P<0.001), has been found. The growing popularity of these products in recent years on the basis of its nutritional properties and beneficial effects, requires additional data and a periodical control. In addition, the present findings are of potential use to food composition tables.     

Heparin Modulates the Mitogenic Activity of Fibroblast Growth Factor by Inducing Dimerization of its Receptor. A 3D View by Using NMR

In vitro mitogenesis assays have shown that sulfated glycosaminoglycans (GAGs; heparin and heparan sulfate) cause an enhancement of the mitogenic activity of fibroblast growth factors (FGFs). Herein, we report that the simultaneous presence of FGF and the GAG is not an essential requisite for this event to take place. Indeed, preincubation with heparin (just before FGF addition) of cells lacking heparan sulfate produced an enhancing effect equivalent to that observed when the GAG and the protein are simultaneously added. A first structural characterization of this effect by analytical ultracentrifugation of a soluble preparation of the heparin‐binding domain of fibroblast growth factor receptor 2 (FGFR2) and a low molecular weight (3 kDa) heparin showed that the GAG induces dimerization of FGFR2. To derive a high resolution structural picture of this molecular recognition process, the interactions of a soluble heparin‐binding domain of FGFR2 with two different homogeneous, synthetic, and mitogenically active sulfated GAGs were analyzed by NMR spectroscopy. These studies, assisted by docking protocols and molecular dynamics simulations, have demonstrated that the interactions of these GAGs with the soluble heparin‐binding domain of FGFR induces formation of an FGFR dimer; its architecture is equivalent to that in one of the two distinct crystallographic structures of FGFR in complex with both heparin and FGF1. This preformation of the FGFR dimer (with similar topology to that of the signaling complex) should favor incorporation of the FGF component to form the final assemblage of the signaling complex, without major entropy penalty. This cascade of events is probably at the heart of the observed activating effect of heparin in FGF‐driven mitogenesis.