Substâncias húmicas: interações com nutrientes e contaminantes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Simple, Direct and Simultaneous Stripping Voltammetric Determination of Lead and Copper in Gasoline Using an In Situ Mercury Film Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Scanned stripping chronopotentiometry at bismuth film rotating disc electrodes: a method for quantitative dynamic metal speciation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Peat humic substances enriched with nutrients for agricultural applications: competion between nutrients and non-essential metals present in tropical soils

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adsorção de metais em solução aquosa pelos processos de batelada e coluna de leito fixo utilizando silsesquioxano funcionalizado com 5-amino-1,3,4-tiadiazol-2-tiol

Pós-graduação em Ciência dos Materiais - FEIS

An EQCM-D study of the influence of chloride on the lead anodic oxidation

The influence of chloride on the electrodeposition of lead films and their dissolution in anodic stripping voltammetric experiments was examined. Gold substrates were plated with lead films, and mass changes were monitored by using the electrochemical quartz crystal microbalance with dissipation factor (EQCM-D). The results showed that the amount of electrodeposited lead is slightly dependent on the chloride concentration. The charge/mass ratio data indicated the presence of Pb(I) and Pb(II) as a result of film dissolution, and the precipitation and deposition of PbCl2 onto the electrode surface. Scanning electron microscopy images revealed that the morphology of the lead film was strongly influenced by chloride present in the plating solution and that much rougher films were obtained in comparison with those obtained in the absence of chloride. The rate of the anodic dissolution was higher for lead films with higher surface areas, which lead to an increase in their stripping voltammetric currents. (C) 2012 Elsevier Ltd. All rights reserved.

Additions- und Umlagerungsreaktionen des Lewis-aciden Dihypersilylplumbandiyls in Umsetzungen mit monodenten und ambidenten Lewis-Basen

Die chemische Reaktivität des Dihypersilylplumbylens Pb[Si(Si(CH3)3)3]2 wird durch seine besondere elektronische Struktur bestimmt. Im Unterschied zu Carbenen (Triplett-Grundzustand) liegen Plumbylene im Grundzustand als Singulett vor, mit einem energetisch hochliegenden HOMO (freies Elektronenpaar mit hohem s-Charakter) und einem tiefliegenden LUMO (näherungsweise: freies p-Orbital des Pb-Atoms). Daraus resultiert das amphotere Lewis-Säure/Lewis-Base-Verhalten der Verbindung, mit der Besonderheit, dass sich die beiden Lewis-Zentren am selben Atom befinden. rnIn Umsetzungen mit monodenten und ambidenten Lewis-Basen wurden die Lewis-aciden Eigenschaften des Dihypersilylplumbandiyls Pb[Si(Si(CH3)3)3]2 untersucht. Reaktionen mit den sterisch anspruchsvollen O-Nucleophilen KOtBu (Kalium-tert-Butanolat) und KOiPrPh (4-Kaliumisopropylphenolat) führten bei tiefen Temperaturen zur primären Adduktbildung. Die aus der Strukturanalyse erhaltenen Bindungsdaten zeigen die extreme sterische Überfrachtung des zentralen Blei-Atoms. Der Abbau der sterischen Spannung ist möglicherweise die Ursache für offensichtlich stattfindende Umlagerungsfolgereaktionen (bei Reaktionsführungen bei T>-60°C), die aufgrund spektroskopische Untersuchungen zu vermuten sind.rnEingehender wurden diese Umlagerungsreaktionen in Umsetzungen des Pb[Si(Si(CH3)3)3]2 mit ambidenten Lewis-Basen untersucht. In Übereinstimmung und Erweiterung mit früheren Ergebnissen von Klinkhammer (K. Klinkhammer, Polyhedron, 2002, 21, 587) konnte beispielsweise die Migration einer (mit der ambidenten Lewis-Base tert-Butylisonitril) bzw. beider Hypersilylgruppen (mit p-Tolylisocyanat) unter Bildung hetero- bzw. homoleptischer Plumbylene nachgewiesen werden.rnReaktionen des Pb[Si(Si(CH3)3)3]2 mit den anorganischen ambidenten Salz-Ionen CN-, OCN-, SCN-, N3-, NO2- führen zur Bildung salzartiger Plumbanide der Zusammensetzung Me{Pb[Si(Si(CH3)3)3]2}Nu (Me: Na bzw. K, Nu: CN, OCN, SCN, N3, NO2). Die Verbindungen liegen im Kristall monomer als Kontaktionenpaar vor. Auf diese Weise gelang erstmalig die gezielte Synthese eines Blei(II)cyanids sowie die Darstellung eines Blei(II)isocyanats. rn

A comparison of histological and immunohistochemical methods for quantifying the pathological lesions of Pick's disease

Counts of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) were made in the frontal and temporal cortex from patients with Pick's disease (PD). Lesions were stained histologically with hematoxylin and eosin (HE) and the Bielschowsky silver impregnation method and labeled immunohistochemically with antibodies raised to ubiquitin and tau. The greatest numbers of PB were revealed by immunohistochemistry. Counts of PB revealed by ubiquitin and tau were highly positively correlated which suggested that the two antibodies recognized virtually identical populations of PB. The greatest numbers of PC were revealed by HE followed by the anti-ubiquitin antibody. However, the correlation between counts was poor, suggesting that HE and ubiquitin revealed different populations of PC. The greatest numbers of SP and NFT were revealed by the Bielschowsky method indicating the presence of Alzheimer-type lesions not revealed by the immunohistochemistry. In addition, more NFT were revealed by the anti-ubiquitin compared with the anti-tau antibody. The data suggested that in PD: (i) the anti-ubiquitin and anti-tau antibodies were equally effective at labeling PB; (ii) both HE and anti-ubiquitin should be used to quantitate PC; and (iii) the Bielschowsky method should be used to quantitate SP and NFT.

Hydrothermal carbonization in the synthesis of sustainable porous carbon materials

Carbon materials are found versatile and applicable in wide range of applications. During the recent years research of carbon materials has focussed on the search of environmentally friendly, sustainable, renewable and low-cost starting material sources as well as simple cost-efficient synthesis techniques. As an alternative synthesis technique in the production of carbon materials hydrothermal carbonization (HTC) has shown a great potential. Depending on the application HTC can be performed as such or as a pretreatment technique. This technique allows synthesis of carbon materials i.e. hydrochars in closed vessel in the presence of water and self-generated pressure at relatively low temperatures (180-250 ˚C). As in many applications well developed porosity and heteroatom distribution are in a key role. Therefore in this study different techniques e.g. varying feedstock, templating and post-treatment in order to introduce these properties to the hydrochars structure were performed. Simple monosaccharides i.e. fructose or glucose and more complex compounds such as cellulose and sludge were performed as starting materials. Addition of secondary precursor e.g. thiophenecarboxaldehyde and ovalbumin was successfully exploited in order to alter heteroatom content. It was shown that well-developed porosity (SBET 550 m2/g) can be achieved via one-pot approach (i.e. exploitation of salt mixture) without conventionally used post-carbonization step. Nitrogen-enriched hydrochars indicated significant Pb(II) and Cr(VI) removal efficiency of 240 mg/g and 68 mg/g respectively. Sulphur addition into carbon network was not found to have enhancing effect on the adsorption of methylene blue or change acidity of the carbon material. However, these hydrochars were found to remove 99.9 % methylene blue and adsorption efficiency of these hydrochars remained over 90 % even after regeneration. In addition to water treatment application N-rich high temperature treated carbon materials were proven applicable as electrocatalyst and electrocatalyst support. Hydrothermal carbonization was shown to be workable technique for the production of carbon materials with variable physico-chemical properties and therefore hydrochars could be applied in several different applications e.g. as alternative low-cost adsorbent for pollutant removal from water.

Síntese e caracterização de ligantes oximas e tiossemicarbazonas e seus complexos

Este trabalho apresenta a síntese e caracterização de cinco ligantes e quatro complexos derivados de oximas e tiossemicarbazonas. Entre essas, discutem-se as estruturas cristalinas/moleculares determinadas por difração de raios-X em monocristais: do ligante 4-feniltiossemicarbazida-isatina (Ligante 5), do complexo piridina-salicilaldeído-4- feniltiossemicarbazona de niquel (II) (Complexo 1), e do bis-4-feniltiossemicarbazonaisatina de chumbo(II) (Complexo 2). A estrutura do Ligante 5 cristaliza no sistema monoclínico, grupo espacial P21/c, com parâmetros de cela a = 6,3227(2) Å, b = 15,7973(7) Å, c = 14,4572(6) Å, β = 93,9330(10)°, V = 1440,61(10) Å3 , Z = 4. O refinamento da estrutura convergiu aos índices de discordância finais R1 = 0,0520, wR2 = 0,1471. Observa-se ainda a ocorrência de interações intermoleculares do tipo ligações de hidrogênio clássicas [N18−H3---O1′ 2,907(2)Å], com a formação de estruturas dímeras inter-relacionadas por simetria dentro da cela cristalina. Para a estrutura cristalina do Complexo 1, observa-se NC=4, e geometria de coordenação quadrada plana, onde o ligante saliciladeído-4-feniltiossemicarbazida comporta-se como quelante tridentado, e completando a esfera de coordenação do centro metálico temos uma molécula de piridina. A estrutura cristaliza no sistema monoclínico, grupo espacial P21/m, parâmetros de cela a = 12,8211(2) Å, b = 5,73370(10) Å, c = 23,9950(4) Å, β = 101,0910(10)°, V = 1730,98(5) Å3 , índices de discordância finais R1= 0,0320, wR2 = 0,0888, Z=3. O Complexo 1 apresenta ainda interações intermoleculares do tipo [N(3)-H(3)---S(1) = 3,5838(17)º, N(3)–H(3A)---S(1) = 160,91(19)º], formando estruturas dímeras e ligação de hidrogênio intramolecular não-clássica do tipo [C(10)-H(10)---N(2) = 2,838(2)º e C(10) – H(10)---N(2) = 122º]. A estrutura cristalina do complexo 2, apresenta duas formas independentes (uma com centro representado por Pb1 e outra por Pb2). Para a unidade com Pb1 temos o complexo composto por duas unidades do Ligante 5, que comportam-se como quelantes tridentados, e a esfera de coordenação é completada por interações intermoleculares do tipo η 2 areno π e através da ligação polarizada com o O1 da moléculas vizinha, o que confere ao íon Pb1 NC=9. A unidade Pb2 apresenta apenas as duas unidades do Ligante 5 coordenadas conferindo-lhe NC=6. A estrutura cristaliza no sistema monoclínico, grupo espacial C2/c, parâmetros de cela a = 37,9747(6) Å, b= 9,51280(10) Å, c = 31,4378(5) Å, β = 125,951(2)°, V= 9193,5(2) Å3 , Z = 4, índices de discordância finais= R1 = 0,0643, wR2 = 0,1227.

Peat humic substances enriched with nutrients for agricultural applications: Competition between nutrients and non-essential metals present in tropical soils

Improved agricultural productivity, and reduction of environmental impacts, require studies of the interactions between different soil components. Fertilizers marketed as "organic" or "natural", such as peats or humic substances (HS) extracted from peats, are enriched with macro and micronutrients that, according to the manufacturers, are released to the plant in accordance with its needs. This work investigates the complexation capacity of HS for macro and micronutrient metal species, considering the competition, for HS complexation sites, between non-essential metals (aluminium and lead), present in the soil, and the nutrients. Humic substances were found to possess strong affinities for Pb(II) and Al(III), forming stable complexes, with concomitant release of complexed nutrients. Although HS are already used commercially as organic fertilizers, further studies of methods of HS enrichment, aimed at avoiding losses, are highly desirable from environmental and economic perspectives. (C) 2009 Elsevier B.V. All rights reserved.

Concentrations of Fe, Mn, Cu, Zn, Co, Ni, Pb, Cd, B, and SiO2 in interstitial waters from bottom sediments of the Atlantis II and Discovery Deeps, Red Sea rift zone

Chemical analyzes show that interstitial waters from ore-bearing bottom sediments of the Atlantis II and Discovery Deeps are enriched in Fe, Mn, Cu, Ni, Co, Zn, Pb, and Cd compared to sea water. Enrichment factors of these trace elements in the interstitial waters of the Atlantis II Deep relative to the sea water vary within the following ranges: for Fe from 100 to 7000, for Mn from 19047 to 32738, for Zn from 500 to 1600, for Pb from 78333 to 190000, for Cu from 107 to 654. Comparison of average weighted concentrations of Fe, Mn, Zn, Pb, Cu, Ni in the bottom sediments and the interstitial waters of the Atlantis II Deep indicates common regularities and good relationship in distribution of these elements along sediment cores. Differences in concentrations and distribution of the studied trace elements in the interstitial waters of the Atlantis II and Discovery Deeps result from different chemical compositions of hydrothermal fluids entering these deeps.

Teaching games level design using the StarCraft II editor

Level design is often characterised as “where the rubber hits the road” in game development. It is a core area of games design, alongside design of game rules and narrative. However, there is a lack of literature dedicated to documenting teaching games design, let alone the more specialised topic of level design. Furthermore, there is a lack of formal frameworks for best practice in level design, as professional game developers often rely on intuition and previous experience. As a result, there is little for games design teachers to draw on when presented with the opportunity to teach a level design unit. In this paper, we discuss the design and implementation of a games level design unit in which students use the StarCraft II Galaxy Editor. We report on two cycles of an action research project, reflecting upon our experiences with respect to student feedback and peer review, and outlining our plans for improving the unit in years to come.