Uma célula eletroquímica de fluxo para modificação permanente de tubo de grafite empregado em absorção atômica

A flow cell assembled on the original geometry of a graphite tube to achieve permanent chemical modifier is proposed. The graphite tube operates as the working electrode. A stainless steel tube, positioned downstream from the working electrode, was used as the auxiliary electrode. The potential value applied on the graphite electrode was measured against a micro reference electrode (Ag/AgCl) inserted into the auxiliary electrode. Palladium solutions in acetate buffer (100 mmol L-1, pH = 4.8), flowing at 0.5 mL min-1 for 60 min was used to perform the electrochemical modification. A mercury solution (1 ng) was used to evaluate the performance of the permanent palladium modifier.

Calcium phosphate glasses: silanation process and effect on the bioactivity behavior of Glass-PMMA composites

This article presents the results of a study of the efficiency of silanation process of calcium phosphate glasses particles and its effect on the bioactivity behavior of glasspoly( methyl methacrylate) (PMMA) composites. Two different calcium phosphate glasses: 44.5CaO-44.5P2O5-11Na2O (BV11) and 44.5CaO-44.5P2O5-6Na2O-5TiO2 (G5) were synthesized and treated with silane coupling agent. The glasses obtained were characterized by Microprobe and BET while the efficiency of silanation process was determined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Thermal Analysis (DTA and TG)techniques. The content of coupling agent chemically tightly bond to the silanated glasses ascended to 1.69 6 0.02 wt % for BV11sil glass and 0.93 6 0.01 wt % for G5sil glass. The in vitro bioactivity test carried out in Simulated Body Fluid (SBF) revealed certain bioactive performance with the use of both silanated glasses in a 30% (by weight) as filler of the PMMA composites because of a superficial deposition of an apatite-like layer with low content of CO3 22 and HPO4 22 in its structure after soaking for 30 days occurred. VC 2013 Wiley Periodicals,Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000-000, 2013.

Improving the Potentials of Logistics Processes: Identification and Solutions

The importance of logistics for companies is a well known and justified issue. Today, enterprises are developing their logistics processes in order to match their products and services to the requirements of the most important customers. Therefore there is a need for developing analysing tools for logistics and especially for analysing the significance of various customer service elements. The aim of this paper is to propose analytic tools for supporting strategic level logistics decision making by emphasizing service level elements on two levels: (1) to introduce and propose approaches to categorize the developing efforts of logistics and (2) to introduce and/or propose approaches for solving some customer service related strategic level logistics problems. This study consists of two parts. In the first part an overview of the work is presented, and the second part comprises eight research papers on the topic of the study. The overview includes an introduction, where strategic and tactical level logistics problems are discussed and the relation of logistics to marketing and customer service issues is presented. In the first part of the study the objectives, the structure, the research strategy and the contribution of the research are described, and the challenges for future research are discussed. In the second part the three first papers deal with the identification of objectives for logistics while the remaining five papaers concentrate on solving customer service related strategic level logistics problems.

Similar problems, different solutions: Comparing refuse collection in the Netherlands and Spain

Local public service provision can vary greatly because of differences in institutional arrangements, public service markets, and national traditions regarding government intervention. In this paper we compare the procedures adopted by the local governments of the Netherlands and Spain in arranging for the provision of solid waste collection. We find that Spain faces a consolidation problem, opting more frequently to implement policies of privatization and cooperation, at the expense of competition. By contrast, the Netherlands has, on average, larger municipalities, resorting somewhat less to privatization and cooperation, and more to competition. The two options - cooperation and competition - have their merits when striving to strike a balance between transaction costs and scale economies. The choices made in organizational reform seem to be related to several factors, among which the nature of the political system and the size of municipalities appear to be relevant.

Glyceraldehyde-3-phosphate dehydrogenase as a moonlighting protein in bacteria

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is considered a housekeeping protein that is present in virtually all organisms, where it performs metabolic functions essential for survival. GAPDH plays an essential role in the process of energy production, and is also involved in numerous biological processes. GAPDH belongs to a subset of proteins called moonlighting proteins, in which different functions are associated with a single polypeptide chain. The multifunctionality of GAPDH has been described in pathogenic and probiotic microorganisms, in mammals and in plants. In this review, we summarize the moonlighting role of GAPDH in bacteria.

Glyceraldehyde-3-phosphate dehydrogenase as a moonlighting protein in bacteria

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is considered a housekeeping protein that is present in virtually all organisms, where it performs metabolic functions essential for survival. GAPDH plays an essential role in the process of energy production, and is also involved in numerous biological processes. GAPDH belongs to a subset of proteins called moonlighting proteins, in which different functions are associated with a single polypeptide chain. The multifunctionality of GAPDH has been described in pathogenic and probiotic microorganisms, in mammals and in plants. In this review, we summarize the moonlighting role of GAPDH in bacteria.

Glyceraldehyde-3-phosphate dehydrogenase as a moonlighting protein in bacteria

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is considered a housekeeping protein that is present in virtually all organisms, where it performs metabolic functions essential for survival. GAPDH plays an essential role in the process of energy production, and is also involved in numerous biological processes. GAPDH belongs to a subset of proteins called moonlighting proteins, in which different functions are associated with a single polypeptide chain. The multifunctionality of GAPDH has been described in pathogenic and probiotic microorganisms, in mammals and in plants. In this review, we summarize the moonlighting role of GAPDH in bacteria.

MONALISA 2.0 and the sea traffic management - a concept creating the need for new maritime information standards and software solutions

Postprint (published version)

Highly eccentric hip-hop solutions of the 2N

We show the existence of families of hip-hop solutions in the equal-mass 2N-body problem which are close to highly eccentric planar elliptic homographic motions of 2N bodies plus small perpendicular non-harmonic oscillations. By introducing a parameter ϵ, the homographic motion and the small amplitude oscillations can be uncoupled into a purely Keplerian homographic motion of fixed period and a vertical oscillation described by a Hill type equation. Small changes in the eccentricity induce large variations in the period of the perpendicular oscillation and give rise, via a Bolzano argument, to resonant periodic solutions of the uncoupled system in a rotating frame. For small ϵ ≠ 0, the topological transversality persists and Brouwer's fixed point theorem shows the existence of this kind of solutions in the full system

On the structure of cooperative and competitive solutions for a generalized assignment game

We study cooperative and competitive solutions for a many- to-many generalization of Shapley and Shubik (1972)'s assignment game. We consider the Core, three other notions of group stability and two al- ternative definitions of competitive equilibrium. We show that (i) each group stable set is closely related with the Core of certain games defined using a proper notion of blocking and (ii) each group stable set contains the set of payoff vectors associated to the two definitions of competitive equilibrium. We also show that all six solutions maintain a strictly nested structure. Moreover, each solution can be identified with a set of ma- trices of (discriminated) prices which indicate how gains from trade are distributed among buyers and sellers. In all cases such matrices arise as solutions of a system of linear inequalities. Hence, all six solutions have the same properties from a structural and computational point of view.

Aplicação de métodos de calibração multivariada para a determinação simultânea de riboflavina (VB2), tiamina (VB1), piridoxina (VB6) e nicotinamida (VPP)

In this work, the artificial neural networks (ANN) and partial least squares (PLS) regression were applied to UV spectral data for quantitative determination of thiamin hydrochloride (VB1), riboflavin phosphate (VB2), pyridoxine hydrochloride (VB6) and nicotinamide (VPP) in pharmaceutical samples. For calibration purposes, commercial samples in 0.2 mol L-1 acetate buffer (pH 4.0) were employed as standards. The concentration ranges used in the calibration step were: 0.1 - 7.5 mg L-1 for VB1, 0.1 - 3.0 mg L-1 for VB2, 0.1 - 3.0 mg L-1 for VB6 and 0.4 - 30.0 mg L-1 for VPP. From the results it is possible to verify that both methods can be successfully applied for these determinations. The similar error values were obtained by using neural network or PLS methods. The proposed methodology is simple, rapid and can be easily used in quality control laboratories.

Obtenció d'estruvita a partir de la fracció líquida digerida de purins de vaca

Actualment a Catalunya existeixen zones amb importants limitacions per l’aplicació de purins al sòl, pel que és imprescindible trobar alternatives de gestió i tractament que permetin l’aprofitament adequat dels recursos continguts a les dejeccions ramaderes sense afectar el medi. La digestió anaeròbia és una de les tècniques utilitzades en el tractament de les dejeccions ramaderes. L’efluent líquid que s’obté d’aquest tractament no modifica el contingut de nitrogen i fòsfor i per tant ha de ser gestionat correctament. L’objectiu general d’aquest projecte és avaluar la precipitació d’estruvita (sal de magnesi, amoni i fosfat) com una alternativa de gestió de l’efluent líquid d’una planta de digestió anaeròbia i compostatge que tracta dejeccions ramaderes conjuntament amb altres residus orgànics. S’han avaluat els efectes dels diferents paràmetres operacionals en la formació d’estruvita (pH, temperatura, velocitat d’agitació, alcalinitat), mitjançant assaigs en discontinu amb solució sintètica. A continuació s’ha procedit a obtenir estruvita a partir de la fracció líquida digerida de purí (FLD), en assaigs en discontinu per estudiar l’efecte del contingut de matèria orgànica i sòlids Totals (ST), així com el contingut en fosfats i el pH de reacció. Finalment, s’han optimitzat els paràmetres de procés en continu, mitjançant la posada en marxa d’un reactor a escala de laboratori i estudi de l’efecte de la velocitat d’agitació i de la introducció del stripping de CO2, tant amb solució sintètica com amb la fracció líquida digerida del purí. Dels resultats obtinguts es pot concloure que els factors que tenen una major influència en el procés d’obtenció d’estruvita són el pH (el pH òptim es situa al voltant de 9), i la presència de matèria orgànica i sòlids ens suspensió, que interfereix de forma quantitativa i qualitativa en la formació de l’estruvita. En el procés en continu s’ha aconseguit reduccions d’un 84% i 98% d’amoni i fòsfor respectivament, obtenintse estruvita que pot ser utilitzada com a fertilitzant d’alliberació lenta. Es pot concloure que la precipitació d’estruvita és una bona alternativa per millorar la gestió de les dejeccions ramaderes alhora que permet recuperar nutrients i tancar cicles. La combinació amb un tractament previ que elimini la matèria orgànica, com podria ser la digestió anaeròbia, i una separació de fases, per eliminar els sòlids en suspensió, es presenta com una configuració amb molts avantatges.

Influence of the temperature and type of salt on the phase equilibrium of peg 1500 + potassium phosphate and peg 1500 + sodium citrate aqueous two-phase systems

The present work analyzed the effect of the temperature and type of salt on the phase equilibrium of aqueous two-phase systems (ATPS) formed by poly (ethylene glycol) (PEG) 1500 + potassium phosphate, from (278.15 to 318.15) K, and PEG 1500 + sodium citrate, from (278.15 to 298.15) K. The rise of the temperature normally increased the slope of the tie line (STL). With respect to the influence of the type of salt, sodium citrate showed better capability to induce phase separation, when compared to potassium phosphate.

Uptake of Hg2+ from aqueous solutions by microporous titano- and zircono-silicates

Being mercury one of the most toxic heavy metals present in the environment, it is of major concern to develop cleanup technologies to remove it from wastewater and recover mercury polluted ecosystems. In this context, we study the potential of some microporous titanosilicates and zirconosilicates for taking up Hg2+ from aqueous solutions. These materials have unique chemical and physical properties, and here we are able to confirm that they readily remove Hg2+ from aqueous solutions. Moreover, the presence of the competitive Mg2+ and Na+, which are some of the dominant cations in natural waters, does not reduce the uptake capacity of some of these materials. Thus, several inorganic materials reported here may have important environmental applications, efficiently removing Hg2+ from aqueous solutions.

Estudo do comportamento do chumbo em latossolos brasileiros tratados com fosfatos: contribuições para a remediação de sítios contaminados

Phosphates have been used for lead immobilization in soils but the influence of soil type is not fully understood. In this work, lead chemical behaviour in two Brazilian latosoils (LA and LV) was studied via treatment with phosphates. The Pb concentration in Toxicity Characteristic Leaching Procedure (TCLP) solutions was decreased in all treatments. After treatment with H3PO4 the Pb concentration in the LA remained within the regulatory limit established by EPA. The ecotoxicological results with Daphnia pulex showed that this treatment reduced the lead bioavailability. Sequential extraction analyses showed that the lead was transferred from the most available to the residual fraction. Relevant decrease of soluble lead was observed in all phosphate treatments.