The purpose of this thesis was to develop an experimental methodology to determine the mechanisms and kinetics of sliding at the interface between a metallic thin film and substrate. A methodology was developed and used to study interfacial sliding of aluminum films on silicon substrates and copper films on fused quartz substrates. The methodology employed a lap shear type of geometry to load the interface between the film and substrate in shear. The results of the studies were inconclusive with regard to interfacial sliding. In the case of Al-Si, the sample fabrication process increased the interfacial amplitude to an extent that the sliding rate was essentially zero. In the case of Cu-Fused Quartz, chromium film was added to the sample to aid the adhesion of Cu to fused quartz and as a result reduced the sliding rate below detectable levels.

Dissertations submitted in compliance with the requirements for the Master's Degree in technology: Biotechnology, Technikon Natal, 2001. / Hexavalent chromium [Cr(VI)] or chromate, is a toxic, water-soluble contaminant present in many soils and industrial eflluents. As a result of contaminated discharges from industrial applications, and inappropriate wastedisposal practices, significant amounts of chromate have found their way into the environment. This poses a health risk to man as well as animals and plants due to the carcinogenicity, mutagenicity, and teratogenicity of chromate. In man, acute, high level exposures to Cr(VI) can result in ulceration of the skin, eyes, and mucous membranes. Exposure of plants to Cr(VI) can result in reduced biomass production, and in extreme cases, death. Upon reduction ofCr(VI) to trivalent chromium [Cr(III], the toxic effects are significantly decreased because of a decrease in the solubility and bioavailability of Cr(III). Traditionally, Cr(VI) has been recovered from aqueous systems using processes exploiting the differential solubility properties described above. The use of chromate reducing bacteria represents a potential mechanism for the development of an efficacious, cost effective alternative to traditional chemical/physical processes for Cr(VI) recovery from the environment. Therefore, the aim of this research was to isolate and identify chromate reducing bacteria from soil, and characterise the chromate reductase enzyme in order to determine the potential of bacteria to detoxify chromate by reduction. Bacteria from soils and wastewater were examined for chromate reducing potential and identified on the basis of biochemical tests and API 20E. Organisms were isolated by the spread plate technique. Species of Pseudomonas maltophilia, Bacillus subtilis, Acinetobacter calcoaceticus, and Cellumonas cellasea were capable of catalyzing the reduction ofCr(VI) to Cr(IlI) in batch experiments. Reduction capability as high as 99% by the isolates was detected from an initial Cr(VI) concentration of 150 mg.L' in batch cultures. Chromate reduction was determined by means of the diphenylcarbazide method and total chromium was measured by atomic absorption spectroscopy. Pseudomonas maltophilia was observed to be the most suited organism for the efficient detoxification ofCr(VI) due to its wide temperature and pH requirements, low substrate utilization, and tolerance to heavy metal ions of'Cu', Cd2+,Zn2+,and Ni2+which commonly appear in industrial eflluents along with Cr(VI). Reduction rate in a batch reactor for this organism was calculated to be 1.75 mg.g+h'. Comparison of the rates of chromate reduction by Cr(VI) grown cells and cells grown without chromate indicated that the chromate reductase activity is constitutive. Reductase activity was detected by means of the lysozyme-EDTA method in aerobically grown cells, with highest specific activity in the cytoplasmic fraction of the cell. The Cr(VI)-reductase was found to be NAD(p)H-dependent and yielded an activity of 3.24 ml.I.mg' of protein in the cytoplasmic fraction. Once optimization of the parameters in the batch reactor was achieved, cells of Ps. maltophilia was immobilized into polyacrylamide gel and packed in a column. Mass balance studies indicated that ca 147 mg.L' chromate passing through the column undergoes reduction with an initial Cr(VI) concentration of 150 mg.L' resulting in a Cr(VI) reduction efficiency of98%. An amount of 0.11 mg.L' remained in the cells, 0.11 mg.L' in the cell wash water, and 1.65 mg.L' was unaccounted for in the mass balance. Chromate reduction rate in the continuous-upflow reactor system was calculated to be 5.34 mg.g'l.h', which was 3-fold higher than that calculated for the batch reactor. Chromium-contaminated industrial eflluent obtained from Sheffield, Natal, and Saayman Danks Electroplaters was pumped into the continuous-upflow reactor containing immobilized cells of Ps. maltophilia to determine the industrial applicability of the reactor to treat chromate-containing effluents. Complete Cr(VI) reduction / M

Ferritic chromium steels are important structural materials for future nuclear fission and fusion reactors due to their advantages over traditional austenitic steels, including low swelling rates, better thermal fatigue resistance, and lower thermal expansion coefficients. Radiation-induced segregation or depletion (RIS/RID) of solute atoms at grain boundaries is considered to be a potentially significant phenomenon for structural materials because of its potentially detrimental role in affecting microstructure and furthermore mechanical properties. However, the behaviour of Cr at grain boundaries in ferritic steels is not well understood. Both segregation and depletion of Cr at grain boundary under irradiation have been previously observed and no clear dependency on irradiation condition or alloy type has been presented. Furthermore, ferritic alloys are known to undergo hardening and embrittlement after thermal aging in the temperature range of 300-550DC and this phenomenon is related with a and a' phase separation occurring in the solid solution. However the low temperature a-a' miscibility gap in the currently used phase diagram is extrapolated from high temperature results and conflicts with many experimental observations. To understand the Cr behaviour at gram boundaries in ferritic steels under irradiation, a systematic approach combining SEM/EBSD, FIB specimen preparation and APT analysis has been developed and successfully applied to a Fe- 15.2at%Cr to investigate the effect of pre-irradiation chemistry, grain boundary misorientation, impurities, irradiation damage, irradiation depth, and other possible factors to get a better understanding of RIS/RID phenomena. Both low sigma boundaries and randomly selected high angle boundaries have been investigated in detail. Systematic differences between the behaviour of different classes of boundaries had been observed, and the operating mechanisms are also discussed in this thesis. The maximum separation method has been applied on APT data to study the C- enriched clusters and Cr-enriched clusters, which were not directly visible on the atom maps. The composition of the Cr-enriched clusters was consistent with a' phase and the irradiation was found to accelerate the nucleation rather than the growth of these clusters. Such results provided important information in re- determining the a-a' phase boundary.

Ph.D. / A comprehensive experimental study of the effects of the spin-density-wave (SDW) on the physical properties of antiferromagnetic , doped with Mn and V, and Cr-Re alloys is reported. The purpose of the study is twofold: c c Al Cr − 1 (i) To gain insight in the anomalous behaviour of the magnetic phase diagram reported for the binary Cr-Al system. (ii) To investigate SDW effects on the anharmonic behaviour of the lattice vibrations of Cr alloys with a member of the transition metals of group-7 in the periodic table. The investigation entails the following measurements: thermal expansion in the temperature range 77 – 450 K for all the specimens, velocity of sound in the temperature range 4 – 300 K for the Cr-Al-V alloys, ultrasonic wave velocity for the Cr-Re alloys as a function of applied pressure (up to 0.242 GPa) at different temperatures and electrical resistivity in the temperature range 77 – 450 K for the Cr-Re alloys. Concentration-temperature magnetic phase diagrams of the (Mn, V) alloy systems were constructed from the measurements. Alloying with Mn, to increase the electron concentration, is observed to drive an incommensurate (I) SDW alloy towards a commensurate (C) SDW state. This results in a triple point, where the ISDW, CSDW and paramagnetic (P) phases coexist on the magnetic phase diagram. A hysteretic first-order ISDW-CSDW/CSDWISDW phase transition line is then observed on the phase diagram for Mn concentrations above the triple point concentration. Adding V, in order to decrease the electron concentration, to an ISDW alloy is found to have the opposite effect. It drives such a system deeper into the region of the ISDW c c Al Cr − 1 c c Al Cr − 1 phase. A CSDW alloy is, on the other hand, driven towards the triple point by addition of V, instead of Mn. c c Al Cr − 1 Theoretical analysis of the magnetic phase diagrams of the (Mn, V) systems confirms a previous suggestion that the Al impurity acts as an electron acceptor in the Cr matrix for c c Al Cr − 1 2 < c at.% Al, as opposed to an electron donor for at.% Al. 2 > c The high-pressure ultrasonic studies on the Cr-Re alloys were used to construct their pressure-temperature ( T p − ) magnetic phase diagrams. Applying hydrostatic pressure to a CSDW Cr-Re alloy induces a hysteretic first-order CSDW-ISDW phase transition at a certain critical pressure, resulting in a triple point on the phase diagram. An interesting aspect of the observations on the Cr-Re alloys is the suggestion of a new phase line, separating pressureinduced and temperature-induced ISDW phases, on the T p − T p − phase diagram. Acoustic-mode Grüneisen parameters, which quantify the lattice anharmonicity, were calculated for the Cr-Re alloys from the high-pressure ultrasonic measurements. The results indicate exceptionally large interactions between the SDW and the long-wavelength longitudinal phonons in Cr-Re alloys. These effects are particularly large in the vicinity of the Néel phase transition temperature. Interactions of the SDW with the shear mode phonons are on the other hand relatively much smaller. The work on the Cr-Re alloys is considered to finally complete studies of the lattice anharmonicity of Cr alloy systems with elements of all the important groups of the periodic table. It now paves the way for developing microscopic theories to explain the unique behaviour of the magneto-elasticity of dilute Cr alloys. / Prof. H.L. Alberts Dr. A.R.E. Prinsloo

Este estudo foi desenvolvido no Instituto de Pesquisas Energéticas e Nucleares IPEN mais especificamente, no Centro de Ciência e Tecnologia dos Materiais CCTM com apoio da empresa Innovatech. Foram estudados tubos de Co-Cr (L605) usados para fabricação de stents coronarianos, aplicação esta que pede um comportamento mecânico específico e biocompatibilidade. Os tubos de CoCr (L605) podem ser adquiridos em duas condições de história térmica: Trabalhado a frio ou com encruamento ou recozido. O tubo recozido se não estiver em condições para a aplicação, dificilmente será possível atingi-las com um novo tratamento térmico. O tubo encruado abre possibilidades para acertar as condições de tratamento térmico e obter a condição ideal de comportamento mecânico, sem comprometer outros aspectos importantes para a aplicação como biocompatibilidade. Foi selecionado um tubo de CoCr (L605) encruado e com uma quantidade grande de precipitados para os testes, foram selecionadas três faixas de temperatura para o tratamento térmico de recozimento uma abaixo do ponto de solubilização (1000°C), uma dentro da temperatura (1175°C) e uma terceira, mais próxima do ponto de fusão alcançável pelo forno (1250°C). Em cada temperatura foram usados quatro períodos de exposição ao forno( 4, 7, 10 e 15 minutos) totalizando uma matriz com 12 condições de tratamento térmico. Em cada tratamento térmico foram incluídas amostras para ensaio de tração e metalografia. O objetivo deste trabalho é estudar os efeitos dos tratamentos térmicos no comportamento mecânico e na microestrutura do material afim de levantar critérios para determinar os melhores parâmetros de tratamento térmico para a aplicação. / This study was developed at IPEN Institute of Energy and Nuclear Research more specifically in CCTM Materials Cience and Tecnology Center, with support of Innovatech Medical. It was studied Co-Cr (L605) tubes used for manufacture of coronary stents, this application require a specific mechanical behavior and biocompatibility. The tubes CoCr (L605) can be acquired in two conditions of thermal history: Cold worked or annealed. If the annealed tube doesn´t have the conditions for the application it is hardly possible to reach them with a new heat treatment. Hardened tube opens up more possibilities to adjust the conditions of thermal treatment and obtain the optimum condition of mechanical behavior without compromising other aspects important for application as biocompatibility. A tube CoCr (L605) Hardened and a relatively large amount of precipitates were selected for the tests, three temperature tracks have been selected for the thermal annealing treatment: below the temperature of solution aneealing(1000 ° C), at solution aneealing(1175 ° C) and a third temperature closest achievable by furnace (1250 ° C). For each temperature four periods of exposure where selected (4, 7, 10 and 15 minutes) totaling a matrix of 12 heat treatment conditions. In each heat treatment, samples for tensile testing and metallography were included. The objective of this work is to study the effects of heat treatment on mechanical behavior and microstructure of the material in order to raise criteria to determine the best heat treatment for the application.

Na área de Química, uma das linhas mais tradicionais de pesquisa envolve o estudo de formação de complexos. Estes trabalhos são realizados de modo sistemático em nossos laboratórios, geralmente envolvendo cátions de metais de transição com vários ligantes (haletos, pseudo-haletos e carboxilatos). A intensa coloração desenvolvida pela maioria dessas reações de complexação, entre um metal e um pseudo-haleto, tem motivado o desenvolvimento de novos métodos espectrofotométricos para a determinação de íons em amostras reais. Espera-se que o crômio(III), da mesma forma que outros metais de transição, como o ferro, níquel e cobalto, forme complexos com o pseudo-haleto denominado azida ou azoteto (N3-). Desta forma, dando continuidade a esta linha de pesquisa, este trabalho teve como objetivo otimizar as condições experimentais para o sistema crômio(III)/azoteto. Diversos parâmetros como acidez, concentração de ligante, natureza e concentração de solvente, bem como o efeito da temperatura, foram investigados. Reunidas as melhores condições (otimização), montou-se o método analítico que possibilita a determinação do metal. As condições ideais empregadas foram: concentração analítica de ligante e ácido perclórico de 493 e 12,0 mmol L-1, respectivamente, numa temperatura de 25ºC, em meio aquoso. Para a determinação no ultravioleta, o tempo de espera para cada medida foi de 1 hora, enquanto que na região do visível, foi de apenas 30 minutos. Os máximos de absorção ocorreram em torno de 646, 480 e 287 nm, com coeficientes de absortividade molar médios de 184±1, 157±1 e (1,481±0,008) 104 L mol-1 cm-1, respectivamente. As condições estabelecidas foram promissoras, permitindo uma boa repetitividade nas regiões do visível e ultravioleta. Para o método desenvolvido, os íons mais interferentes na região do visível foram: Fe3+, Co2+ e Cu2+ e, na região do ultravioleta, foram HC8H4O4-, Fe3+, Cu2+ e Hg2+. Por meio de um sistema com duas equações, a determinação simultânea de crômio e ferro mostrou-se possível e com erros dentro dos limites analiticamente aceitáveis. Sem a utilização do sistema de equações, verificou-se ainda a possibilidade de se determinar crômio diretamente, mesmo na presença de ferro, no comprimento de onda de 646,5 nm, com um erro menor que 5%, desde que a concentração de ferro não ultrapasse 4 mg L-1. Aplicações analíticas para o método proposto foram testadas em dois suplementos alimentares contendo crômio. Os resultados foram comparados e mostraram-se concordantes com os da técnica de espectrometria de absorção atômica, para o suplemento contendo crômio quelato. Para o suplemento alimentar contendo picolinato de crômio, houve uma discordância dos resultados, indicando a existência de interferentes da matriz que não puderam ser eliminados. Um teste com uma amostra sintética de crômio mostrou um erro de cerca de 1,0% para o método proposto. Em condições ideais, e com um controle dos interferentes presentes, o método proposto mostra-se preciso, simples e barato. Considerando valores de absorbância entre 0,2 e 0,8 (faixa ideal), pode-se determinar o metal nos intervalos de 1,27 a 5,09 mmol L-1 a 480,5 nm, de 1,09 a 4,35 mmol L-1 a 646,5 nm e, finalmente, entre 0,702 a 2,81 mg L-1 no ultravioleta (287 nm). / In Chemistry, the study of complexes formation is one of the most traditional research lines. These studies are done under systematic manners in our laboratories, usually involving metallic transition cations with several ligands (halides, pseudohalides and carboxylates). The intense coloration developed by the major part of those complexation reactions, between a metal and a pseudohalide, has encouraged the development of new spectrophotometric methods for determination of ions in real samples. Conforming others transition metals, (iron, nickel and cobalt), which form complexes with the pseudohalide azide (N3-), we tried to observe the same behavior to chromium(III). Continuing this research line, this work had as principal objectives optimizes the experimental conditions for the chromium(III)/azide system. Several parameters were investigated as acidity, ligand concentration, nature and solvent concentration, as well as temperature effect for optimization of experimental conditions. Gathering all these conditions, the analytical methods were tested for the metal determination. The ideal conditions employed were: analytical ligand concentration and perchloric acid of 493 and 12.0 mmol L-l respectively, at 25 °C, in aqueous medium. For the studies in the ultraviolet region, the contact time before the measures was one hour, while for studies in the visible band measures were made after 30 minutes. The wavelengths of maximum absorption were encountered at 646, 480 and 287 nm, with molar absorptivity coefficients (mean) of 184±1, 157±1 and (1.481±0,008) 104 L mol-1 cm-1, respectively. The established conditions were promising, allowing a good precision in the visible and ultraviolet region. For the developed method, the more interfering ions on visible band were: Fe3+, Co2+ and Cu2+ and, on the ultraviolet band, were HC8H4O4-, Fe3+, Cu2+ and Hg2+. Through a system of two equations, the simultaneous determination of chromium and iron ions was possible with errors within the tolerance range. Without the simultaneous equations system, it was verified directly the possibility of chromium determination in the presence of iron, at a wavelength of 646.5 nm, with an error smaller than 5%, since the concentration of iron doesn’t exceed 4 mg L-l. In this proposed method, analytical applications were tested for two alimentary supplements containing chromium. The results were compared, being concordant with those of atomic absorption technique for the supplement containing chromium chelate, while for the alimentary supplement containing chromium picolinate, the results were in disagreement with the results, indicating the existence of matrix interferences which could not be eliminated. A test with a synthetic sample of chromium had an error of about 1.0% for the proposed method. Under ideal conditions, and with some control of possible interfering, the proposed method can be precise, accurate, simple and cheap. Considering the absorbance values between 0.2 and 0.8 (ideal range), the metal can be determined from 1.27 to 5.09 mmol L-l in 480 nm; 1.09 to 4.35 mmol L-l in 646 nm and, finally, from 0.702 to 2.81 mg L-l at 287 nm (ultraviolet).

Foi estudado o efeito da variação do teor de cromo, em 3%, 6% e 9% em massa, na microestrutura, dureza e oxidação de um ferro fundido branco multicomponente. O Thermo-Calc versão 5 foi a ferramenta utilizada para cálculos termodinâmicos que resultaram na previsão das fases formadas para cada liga. Experimentalmente, foram realizados os seguintes estudos: i) caracterização microestrutural das ligas fundidas com os diferentes teores de cromo na condição bruta de fundição; ii) ensaio de dureza na matriz duplamente revenida em cinco diferentes temperaturas entre 400 °C e 600 °C; e iii) ensaio de termogravimetria em atmosfera controlada de 71,2 % N2 + 17,8 % O2 + 11% H2O, com temperatura constante em 650 °C e por um tempo de 240 minutos. O resultado da caracterização microestrutural permitiu identificar que, com o aumento do teor de cromo, houve aumento da fração volumétrica de carbonetos eutéticos e redução do espaçamento dendrítico secundário. Com as medidas de dureza da matriz após tratamento térmico verificou-se que, independentemente do teor de cromo, o pico de máxima dureza ocorre na temperatura de duplo revenimento de 550°C e, nessa temperatura, a amostra com 9% de cromo exibiu o maior valor de dureza. O ganho de massa das amostras submetidas ao ensaio de termogravimetria foi inversamente proporcional ao aumento de teor de cromo e todas as ligas apresentaram cinética de oxidação parabólica. A caracterização da seção transversal das amostras oxidadas, realizada por meio de um FIB, permitiu identificar, na amostra com 9% de cromo, uma nano camada de óxido de cromo, estrutura decisiva para a menor taxa de oxidação. Os resultados desse estudo permitem concluir que a variação do teor de cromo afeta de maneira significativa a resistência à oxidação, a dureza da matriz e a fração volumétrica de carbonetos eutéticos. / The effect of chromium variation, 3%, 6% and 9% Cr in mass in the microstructure, hardness and oxidation of a Multicomponent White Cast Iron was studied. The Thermo-Calc software version 5 was the tool used for thermodynamic calculations to predict the phases formed for each alloy. Experimentally, the following studies were carried out: i) microstructure characterization of the as cast alloys with the different chromium contents, ii) hardness test in the double tempered matrix at five different temperature between 400°C and 600° and iii) themogravimetric test with steam atmosphere composed of 71,2 % N2 + 17,8 % O2 + 11% H2O at constant temperature of 650° for 240 minutes. The result of the microstructure characterization allowed to observe that with increasing chromium content, there was an increase in the volume fraction of eutectic carbides and a reduction of the secondary dendritic spacing. Independently of the chromium content, a maximum hardness was observed always for double tempered at 550°C and the alloy with 9% of chromium exhibited the highest hardness average value. The final weight gain was inversely proportional to the increase in chromium content and all alloys showed parabolic oxidation kinetics. The alloy with 9% Cr showed the lowest final mass gain and the surface characterization of the sample after oxidation was carried out and the cross section of the sample was performed by FIB and was observed the formation of a nano-oxide layer on the alloy surface with 9% Cr. The results of this study leads to the conclusion that the chromium content variation significantly affects the oxidation resistance, the final hardness of the matrix and the volume fraction of eutectic carbides.

Wu Xiujuan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 88-93). / Abstracts in English and Chinese. / ABSTRACT (Chinese) / ABSTRACT / ACKNOWLEDGEMENT / TABLE OF CONTENTS / LIST OF TABLES / LIST OF FIGURES / Chapter CHAPTER ONE: --- INTRODUCTION / Chapter 1.1 --- General B ackground --- p.1 / Chapter 1.2 --- Chromium in Environment and its Analysis --- p.2 / Chapter 1.2.1 --- Source of Chromium and its Harmful Effects on Human --- p.2 / Chapter 1.2.2 --- Methods for Separation and Determination of Chromium Species --- p.4 / Chapter 1.3 --- Arsenic in the Environment and its Toxicity --- p.4 / Chapter 1.4 --- Properties of TiO2 and Its Applications --- p.6 / Chapter 1.4.1 --- Photocatalytic Property of TiO2 --- p.6 / Chapter 1.4.2 --- Surface Acid-Basic Property of TiO2 --- p.8 / Chapter 1.5 --- Adsorption --- p.11 / Chapter 1.6 --- Fundamental of ICP-AES and ICP-MS --- p.12 / Chapter 1.6.l --- Principle of ICP-AES --- p.12 / Chapter 1.6.2 --- Principle of ICP-MS --- p.14 / Chapter 1.7 --- Scope of Work --- p.18 / Chapter CHAPTER TWO: --- SEPERATION OF CHROMIUM SPECIES ON TIO2 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Experimental --- p.23 / Chapter 2.2.1 --- Materials --- p.23 / Chapter 2.2.2 --- Instruments --- p.24 / Chapter 2.2.2.1 --- Coupling of TiO2 column and ICP-AES --- p.24 / Chapter 2.2.2.2 --- Coupling of TiO2 column and ICP-MS --- p.26 / Chapter 2.2.3. --- Procedure --- p.29 / Chapter 2.3 --- Results and Discussion --- p.33 / Chapter 2.3.1 --- Preliminary study on the adsorption of Cr(III) and Cr(VI) on TiO2 --- p.33 / Chapter 2.3.2 --- Development and Verification of the proposed method for speciation of Cr(III) and Cr(VI) in aqueous solution --- p.42 / Chapter 2.3.3 --- Practical application of the proposed method for separation and determination of Cr(III) and Cr(VI) --- p.46 / Chapter CHAPTER THREE: --- ADSORPTION OF ARSENIC SPECIES ON TiO2 / Chapter 3.1 --- Introduction --- p.61 / Chapter 3.2 --- Experimental --- p.66 / Chapter 3.2.1 --- Materials --- p.66 / Chapter 3.2.2 --- Instruments --- p.69 / Chapter 3.2.3 --- Procedure --- p.70 / Chapter 3.3 --- Results and Discussion --- p.71 / Chapter 3.3.1 --- Adsorption Kinetics --- p.71 / Chapter 3.3.2 --- Effect of pH on Adsorption of Arsenic Species --- p.71 / Chapter 3.3.3 --- Adsorption Isotherm --- p.74 / Chapter 3.3.4 --- Adsorption Model --- p.76 / Chapter 3.3.5 --- Factors Affecting the Adsorption of Arsenic Species on p25 and Rutile TiO2 --- p.83 / Chapter CHAPTER FOUR: --- CONCLUSION --- p.86 / REFERENCES --- p.88

Orientador: Flávio Ruas de Moraes / Banca: Hugo Alberto Domitrovic / Banca: Sergio Fonseca Zaiden / Banca: Joaquim Gonçalves Machado Neto / Banca: Laura Satiko Okada / Resumo: Este trabalho teve por objetivos avaliar as respostas sistêmicas induzidas pela injeção intraperitoneal de 3,0 mg/kg de lipopolissacrídeo (LPS) de Escherichia coli e os eventuais efeitos da suplementação alimentar com cromo trivalente. Para tanto foram utilizados 300 pacus Piaractus mesopotamicus (Holmberg, 1887) pesando em média 80 g; distribuídos em 20 aquários e cinco tratamentos, quais sejam um grupo Controle, não suplementado e que não recebeu LPS; um grupo que recebeu somente LPS e outros três, CRa, CRb e CRc que receberam LPS e dois, quatro e seis partes por milhão de cromo trivalente na ração. Material para determinação de hematócrito, concentração plasmática de cortisol e glicose, concentração de glicogênio hepático, índice hepatossomático e avaliação histológica de brânquias foram colhidos antes e um, dois, quatro, nove, 14, 19 e 24 dias após a injeção do LPS. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 5 x 8, com 4 repetições representadas pelos aquários. Os resultados demonstraram que os níveis de cortisol circulantes aumentaram em todos os grupos assim como houve incremento do estoque de glicogênio hepático. O hematócrito não apresentou diferença significativa e as brânquias apresentaram ligeiras modificações estruturais / Abstract: This work had for objectives to evaluate the response systemic induced by the injection intraperitoneal of 3,0 mg/kg of lipopolissacharideo (LPS) of Escherichia coli and the eventual effects of the alimentary supplementation with mixed trivalent chromium to the ration. Were used three hundred fish Piaractus mesopotamicus (Holmberg, 1887), weighing 80 g on average.; distributed in 20 aquariums and five treatments, which are a group control, non supplemented and that didn't receive LPS; a group that received only LPS and other three, CRa, CRb and CRc that received LPS and two, four six parts for millions of trivalent chrome in the ration. Material for haematocrit determination, concentration cortisol plasmático and glucose, concentration of hepatic glycogen, index hepatosomático and modifications in the branchial structure were appraised by histology picked before and a, two, four, nine, 14, 19 and 24 days after the injection of LPS. The experimental design was randomized entirely, in a 5 x 8 factorial. The results demonstrated that the levels of circulating cortisol increased in all the groups as well as there was increment of the stock of hepatic glycogen. The haematocrit didn't present significant difference and the gills presented quick structural modifications / Doutor

Uma das principais consequências dos processos de mineração e beneficiamento do carvão é a elevada produção de rejeitos. Esses materiais retornam às cavas de mineração ocasionando efeitos negativos ao meio ambiente, como a drenagem ácida de mina. Uma alternativa em potencial para esses rejeitos é aplica-los no tratamento de efluentes líquidos como sólidos sorventes. Dentre os principais poluentes aquosos destacam-se os metais pesados e, entre eles, o cromo hexavalente, devido aos seus efeitos carcinogênicos e mutagênicos, sendo altamente prejudicial aos organismos vivos. Neste contexto, o presente trabalho tem como objetivo utilizar o rejeito do beneficiamento do carvão de Moatize (Moçambique) como sólido sorvente para a remoção de cromo hexavalente de águas contaminadas. O sólido foi utilizado em duas granulometrias diferentes: no intervalo entre 0,7 e 1,5 mm (R1) e menor que 0,074 mm (R2). As amostras foram caracterizadas segundo sua massa específica, densidade aparente, área superficial (BET), volume de poros e diâmetro de poros (BJH), ponto de carga zero, composição química (FRX) e mineralógica (DRX). Ensaios experimentais foram realizados a fim de determinar as melhores condições de sorção, onde foram avaliados o efeito do pH, do tempo de residência e da concentração de sorvente As melhores condições encontradas para o sólido R1 foram: pH 2, 10 h de ensaio e concentração de sorvente de 8 g L-1, onde foi obtido 98,6% de remoção de Cr(VI). A maior remoção para o sólido R2 foi de 98,8%, obtida utilizando-se: pH 2, 50 min de ensaio e concentração de sorvente de 10 g L-1. Comparando com o limite previsto pela legislação brasileira CONAMA 430 para despejos industriais as concentrações finais de cromo hexavalente em solução ficaram abaixo do valor máximo estabelecido (0,1 mg L-1). A partir destas condições encontradas, foram construídas isotermas de equilíbrio e os modelos de Langmuir, Freundlich e Sips foram ajustados aos dados experimentais. Para o sólido R1, os modelos de Langmuir e Sips demostraram um bom ajuste, apresentando valores de R2 de 0,897 e 0,907 respectivamente. Já para o sólido R2, o modelo de Sips foi o que melhor representou os dados experimentais, com um R2 de 0,954. Os resultados encontrados indicam que o rejeito de carvão de Moatize pode ser utilizado para o tratamento de águas contaminadas com cromo hexavalente. / One of the main consequences of coal mining and beneficiation process is the large production of waste and by-products. These materials return to the mines generating significant negative impacts to the environment. One of the possible applications for the coal wastes is in the wastewater treatments, where it can be used as a sorbent. Amongst the main water pollutants, heavy metals stand out, especially hexavalent chromium, due to its carcinogenic and mutagenic effects, being highly prejudicial to the living organisms. In this context, the objective of this study is to use coal beneficiation waste from Moatize (Mozambique) as a sorbent to remove hexavalent chromium from aqueous solution. Coal waste was utilized in two different particle sizes: between 0.7 and 1.5 mm and smaller than 0.074 mm. These solids were characterized for their specific weight, bulk density, superficial area (BET), pore volume and diameter (BJH), point of zero charge, chemical composition (XRF) and mineral composition (XRD). Experiments were conducted to determinate the best sorption conditions, were the operating parameters investigated were: solution pH, contact time and sorbent concentration The best conditions for Cr(VI) sorption onto R1 were: pH 2, 10 h and 8 g L-1 of sorbent concentration, were 98.6% removal was obtained. Cr(VI) maximum removal onto R2 of 98.8% was achieved at pH 2, 50 min and 10 g L-1 of sorbent concentration. Comparing with the limit permitted by Brazilian legislation, CONAMA 430, for industrial wastewaters, the final Cr(VI) concentration in water were below the maximum established by law (0.1 mg L-1). From these results, equilibrium isotherms were build and the mathematical models of Langmuir, Freundlich and Sips were fitted to the experimental data. For the R1 sorbent, Langmuir and Sips models fitted better the experiments, with R2 values of 0.897 and 0.907, respectively. Sips model described better the experimental data when the R2 sorbent was used, with a R2 of 0.954. Results showed that Moatize’s coal waste can be utilized for hexavalent chromium wastewater treatment.