Multinuclear NMR study of the complexes of 6-phospho-D-gluconic acid with W(VI) and Mo(VI)

Three and six complexes have been identified with tungstate and molybdate, respectively, in aqueous solution, depending on pH and concentration; the structure of an important species formed with Mo(VI) is shown.http://www.sciencedirect.com/science/article/B6TFF-4CYWMWH-1/1/064ccb9bfba9c9434e0b22290129fed

Thermomechanical analysis of cold formed steel sections

This work presents an experimental study about cold formed steel elements submitted to compression loads. The sections analyzed are C and Z sections made of steel sheet with 1.5 and 2 [mm] thick and three different cross section heights. The compression tests were made at ambient and elevated temperatures. In both cases a pined support was developed and used. The member resistance at ambient temperature was determined by applying an increasing compression load until the member collapse was achieved. The fire tests were performed in a fire resistance furnace, using the same type of end supports, and a mechanical load given by a specific degree of utilization that is maintained constant during the fire test. These tests allow the determination of the fire resistance time and member critical temperature. The experimental results are compared with the ones obtained with the Eurocode simplified models.info:eu-repo/semantics/publishedVersio

Thermomechanical analysis of cold formed steel sections

This work presents an experimental study about cold formed steel elements submitted to compression loads. The sections analyzed are C and Z sections made of steel sheet with 1.5 and 2 [mm] thick and three different cross section heights. The compression tests were made at ambient and elevated temperatures. In both cases a pined support was developed and used. The member resistance at ambient temperature was determined by applying an increasing compression load until the member collapse was achieved. The fire tests were performed in a fire resistance furnace, using the same type of end supports, and a mechanical load given by a specific degree of utilization that is maintained constant during the fire test. These tests allow the determination of the fire resistance time and member critical temperature. The experimental results are compared with the ones obtained with the Eurocode simplified models.info:eu-repo/semantics/publishedVersio

Le magmatisme terminal de la chaîne hercynienne : signification géodynamique d'une association magmatique identifiée dans le Carbonifère terminal du Massif Hercynien Central Marocain

Na parte oriental do Maciço Hercínico Central de Marrocos afloram alguns filões intercalados em formações do Carbónico superior do Sudeste da bacia de Azrou-Kénifra. Estes filões instalaram-se paralelamente à estratificação e foram deformados por dobramentos associados aos cavalgamentos que controlaram a sedimentação, o que demonstra o seu carácter sintectónico. A sua composição química permitiu distinguir dois tipos de sequências magmáticas sobrepostas nas séries de Tariwalt e Talgarat, respectivamente de idades V3b e Namuriano-V3c, provável. A primeira inclui rochas básicas de carácter transicional e afinidade alcalina, enquanto a segunda possui uma assinatura calco-alcalina. Estas sequências magmáticas apresentam estreitas semelhanças petrográficas e geoquímicas com as que ocorrem em ambientes de margem activa. As assinaturas geoquímicas e a evolução magmática destas rochas são compatíveis com os dados tectono-sedimentares que caracterizam a bacia de Azrou-Kénifra como uma bacia desenvolvida em regime compressivo, integrada num sistema de "avant pays" determinado por sequências de cavalgamentos propagando-se para NW

Theoretical and experimental insights into the complexation of 8-hydroxyquinoline-5-sulfonate with divalent ions of Group 12 metals

The complexation of 8-hydroxyquinoline-5-sulfonic acid with cadmium(II) and mercury(II) has been studied in aqueous solutions using UV/visible absorption, fluorescence and 1H NMR spectroscopy, accompanied by DFT calculations. Results are compared with the behavior of zinc(II) and show in all cases the dominant formation of a 1:2 (metal:ligand) complex. DFT calculations under PCM (water) conditions indicate a preference for hexacoordinated metal centers with two ligands and two water molecules. However, while the zinc(II) complex has a square bipyramidal geometry, with the two 8-HQS ligands and metal in the same plane and two coordinated water molecules mutually trans, with cadmium(II) and mercury(II), the isomers in which the water molecules are in the cis geometry are more stable. Changes in UV–Vis absorption, fluorescence spectra and fluorescence intensity are observed on complexation. Fluorescence quantum yields follow the order Zn/8-HQS Hg/8-HQS. We believe two competing factors may be involved: an increase in fluorescence on going from Zn(II) to Cd(II) due to increased stability, and a decrease on going increasing atomic number of the metal ion due to the heavy atom effect which increases intersystem crossing. Triplet state quantum yields were measured for the Zn(II) and Cd(II) complexes, and the value for the cadmium(II) complex is higher, in agreement with the heavy atom effect. However, the sum of fluorescence and triplet quantum yields in these cases is less than unity. It is suggested that there is a competing non-radiative route for deactivation of the excited state through ligand or solvent exchange. This provides a ready explanation of increased fluorescence yields when metal/8-HQS complexes are immobilized in solid matrices

Using Lanthanides as Probes for Polyelectrolyte-Metal Ion Interactions. Hydration Changes on Binding of Trivalent Cations to Nucleotides and Nucleic Acids

http://www.sciencedirect.com/science/article/B6TFM-4SWFNW8-1/1/aadd2972e76576ca7bf5c347abd5a68

Maxilla bone pre-surgical evaluation aided by 3D models obtained by rapid prototyping

For implant planning and placement, the association of CAD and CAM techniques furnishes some advantages, regarding 3D determination of the patient’s jaw anatomy and fabrication of both anatomical models and surgical guides (Verstreken et al. 1996). In this paper we will present Rapid Prototype (RP) use as a tool, able to produce solid models of a maxilla in order to allow pre-surgical conditions evaluation in a pa-tient who has lost bone tissue and needs dental implants. In this process, three-dimensional reconstruction has been made from a bi-dimensional image file, obtained by Computerized Tomography (CT) and a set of partial and total biomedical models have been manufactured to allow maxilla analysis. Rapid Prototyping technique used has been three-dimensional printing (TDP or 3DP) which allows a good reality simulation

Nouvelles observations dans le dépocentre volcano-sédimentaire carbonifère du Massif du Tazekka, Moyen-Atlas, Maroc : implications sur l'évolution géodynamique de la chaîne Hercynienne

A análise integrada das estruturas tectónicas e das fácies do Complexo Vulcano Sedimentar do Maciço de Tazekka sugere que este, à escala da grande bacia carbonífera de ante país da Meseta Oriental marroquina, corresponde a um depocentro ou sub bacia em compressão controlada pela propagação, para NW, de dobras de amortecimento do cavalgamento de Hajra Sbaa el Caid. As sequências tectono sedimentares, detrito conglomeráticas e/ou tufíticas, estão associadas a um magmatismo extrusivo com basaltos, andesitos, dacitos, riodacitos e riólitos homogéneos ou piroclásticos com blocos re sedimentados. Estes vulcanitos correspondem a uma sequência sub alcalina equivalente. As sequências calco alcalinas orogénicas características de ambientes de subducção. Estes resultados, assim como a comparação das idades de contracção regional na Meseta marroquina, permitem integrar o Maciço de Tazekka num contexto de wedge top deepzone dum sistema de bacias de ante país flexural, em compressão comandada pela progressão de duas sequências de cavalgamentos prógrados, de NW, desde o Fameno Tournaisiano ao Viseano sup. Terminal Westfaliano inf., da Meseta Oriental para a Meseta Ocidental, em Marrocos setentrional

Interactions of vanadates with carbohydrates in aqueous solutions

The interaction between the vanadate ion (VO3-, i.e. vanadium (V)) and the carbohydrates sucrose, glucose and fructose has been studied in aqueous solutions (pH [approximate]6, 298.15 K) using measurements of diffusion coefficients, electrical conductivity, Raman and multinuclear NMR spectroscopy. With sucrose and glucose, indications of hydrolysis of the anion in the absence of the sugars came from a decrease in the diffusion coefficient with increasing concentration. Significant effects on the diffusion coefficients were observed in the presence of sucrose and glucose, suggesting interactions between the carbohydrates and vanadate ion. Support for this came from electrical conductivity measurements, where there were indications of formation of oligomeric species. These were found to depend on the carbohydrate used: confirmation of oligomer formation came from Raman spectroscopy, where it was possible to identify these species, and see their dependence on the particular carbohydrate used. Information on the interactions between the carbohydrates glucose or sucrose and vanadate came from 51V and 1H NMR spectroscopy, where the dominant species appeared to be a 2:2 complex with glucose, possessing trigonal bipyramidal centres, whereas with sucrose it is suggested that octahedral species are formed. Studies with fructose were complicated by competing oxidation of this carbohydrate and reduction of vanadium (V).http://www.sciencedirect.com/science/article/B6TGS-4CTN53R-3/1/7da9099617b4eef5113ec0db3254629

Stability and enzymatic studies with omeprazole: hydroxypropyl-β-cyclodextrin

The original publication is available at www.springerlink.com. A publicação original está disponível em www.springerlink.comOmeprazole (OME) exhibits low stability to light, heat and humidity. In stress conditions OME stability should improve under inclusion complex form with hydroxypropyl-b-cyclodextrin (HPbCD). Stability of OME, its physical mixture (PM) with HPbCD and OME:HPbCD inclusion complex was assessed during 60 days. The inclusion complexes were prepared by kneading and freezedrying techniques and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). A molecular modelling was also held to predict the most probable tridimensional conformation of inclusion complex OME:HPbCD. The inhibitory activity of free and complexed OME on selected enzymes, namely, papain (protease model of the proton pump) and acetylcholinesterase (enzyme present in cholinergic neurons and also involved in Alzheimer’s disease) was compared. The results obtained show that HPbCD do not protect against OME degradation, in any prepared powder, in the presence of light, heat and humidity. This may indicate that the reactive group of OME is not included in the HPbCD cavity. This fact is supported by molecular modelling data, which demonstrated that 2-pyridylmethyl group of OME is not included into the cyclodextrin cavity. In relation to enzymatic assays it was observed that free OME and OME in the binary systems showed identical inhibitory activity on papain and acethylcolinesterase, concluding that HPbCD do not affect OME activity on these two enzymes