<p>This study has been triggered by the fact that stainless steel is being increasingly used in new applications, where possible environmental effects may be a matter of concern. When stainless steel is exposed to a given environment, a key issue is the release of small amounts of the main alloying elements iron, chromium, nickel and molybdenum. Published release rate data of these elements turned out to be sparse. Furthermore, only little was known about the role of different parameters that may affect the release rate, such as degree of alloying, exposure time and surface finish. Hence, the aim of this study was to develop methodological means and to provide accurate metal release rates of alloying constituents from different grades of stainless steels- austenitic, ferritic and duplex- when exposed to selected environments: artificial rain and synthetic body fluids. The results and discussion have been summarised in this thesis by formulating and answering ten questions, all believed to be crucial for the understanding of possible environmental effects of stainless steels.</p><p>Some common conclusions could be drawn, independent of stainless steel grade and exposure condition. Iron was always preferentially released, and the release rates of chromium, nickel and molybdenum (when measured) were significantly lower than of iron, also when considering the bulk proportion of these elements. The release rate of all elements was initially high and decreased with exposure time, mainly because of an observed enrichment of chromium in the passive film formed.</p><p>The release rates of iron (2 μgcm^-2week^-1) and nickel (0.08 μgcm-²week-¹) from stainless steel from grades 304 and 316 exposed to artificial rain were much lower than corresponding rates for the pure metals (750 μgcm-²week^-1 released Fe and 15 μgcm^-2week^-1 released Ni), whereas chromium exhibited similar release rates from stainless steel and the pure metal (0.1 μgcm^-2week^-1). This implies that the common procedure to calculate release rates, based on the pure metals and the nominal steel composition, significantly overestimates release rates of iron and nickel from stainless steel, but not of chromium.</p><p>Total release rates from seven stainless steel grades in synthetic body fluid were found to decrease with increasing alloy content in the following release rate order: grade 409 >> grade 430 > grades 316L ≈ 201 ≈ 2205 ≈ 304 > grade 310. The release rate was highly sensitive to pH of the synthetic body fluid but only slightly sensitive to stainless steel surface finish.</p>

<p>Humans are exposed to metals and metal-containing materials daily, either conscious, e.g. using metal tools or objects, or unconscious, e.g. during exposure to airborne metal-, and metal-containing particles. The diffuse dispersion of metals from different sources in the society, and the concern related to its potential risk for adverse effects on humans have gained an increased public and governmental attention both on a national and international level. In this context, the knowledge on metal release from metallic objects or metal-containing particles is essential for health risk assessment.</p><p>This thesis focuses on the study of metal release from powder particles of stainless steel and Cu-based materials exposed to synthetic body fluids mainly for simulating lung-like environments. The study comprises: i) development of a suitable experimental method for metal release studies of micron sized particles, ii) metal release data of individual alloy constituents from stainless steel powder particles of different particle sizes, and iii) Cu release from different Cu-based powder particles. In addition, the influence of chemical and physical properties of metallic particles and the test media are investigated. Selected results from Ni powder particles exposed to artificial sweat are presented for comparison. The outcome of this research is summarized through ten questions that are formulated to improve the general understanding of corrosion-induced metal release from metallic particles from a health risk perspective.</p><p>A robust, reproducible, fairly simple, and straightforward experimental procedure was elaborated for metal release studies on particles of micron or submicron size. Results in terms of metal release rates show, for stainless steel powder particles, generally very low metal release rates due to a protective surface oxide film, and Fe preferentially released compared to Cr and Ni. Metal release rates are time-dependent for both stainless steel powder particles and the different Cu-containing powders investigated. The release of Cu from the Cu-containing particles depends on the chemical and compositional properties of the Cu-based material, being either corrosion-induced or chemically dissolved. Moreover, the test medium also influences the metal release process. The metal release rate increases generally with decreasing pH of the test media. However, even at a comparable pH, the release rate may be different due to differences in the interaction between the particle surface and specific media.</p><p>The nature of particles is essentially different compared to massive sheet in terms of physical shape, surface composition and morphology. The surface area, and even the surface composition of metallic particles, depend on the particle size. The specific surface area of particles, area per mass, is intimately related to the particle size and has a large effect on the metal release process. Release rates increase with decreasing particle size due to a larger active surface area that takes part in the corrosion/dissolution process. The surface area that actually is active in the corrosion and metal release process (the effective area) governs the metal release process for both particles and massive sheet of metals or alloys. For particles, the effective surface area depends also on agglomeration conditions of particles during exposure.</p>

This study has been triggered by the fact that stainless steel is being increasingly used in new applications, where possible environmental effects may be a matter of concern. When stainless steel is exposed to a given environment, a key issue is the release of small amounts of the main alloying elements iron, chromium, nickel and molybdenum. Published release rate data of these elements turned out to be sparse. Furthermore, only little was known about the role of different parameters that may affect the release rate, such as degree of alloying, exposure time and surface finish. Hence, the aim of this study was to develop methodological means and to provide accurate metal release rates of alloying constituents from different grades of stainless steels- austenitic, ferritic and duplex- when exposed to selected environments: artificial rain and synthetic body fluids. The results and discussion have been summarised in this thesis by formulating and answering ten questions, all believed to be crucial for the understanding of possible environmental effects of stainless steels. Some common conclusions could be drawn, independent of stainless steel grade and exposure condition. Iron was always preferentially released, and the release rates of chromium, nickel and molybdenum (when measured) were significantly lower than of iron, also when considering the bulk proportion of these elements. The release rate of all elements was initially high and decreased with exposure time, mainly because of an observed enrichment of chromium in the passive film formed. The release rates of iron (2 μgcm-2week-1) and nickel (0.08 μgcm-2week-1) from stainless steel from grades 304 and 316 exposed to artificial rain were much lower than corresponding rates for the pure metals (750 μgcm-2week-1 released Fe and 15 μgcm-2week-1 released Ni), whereas chromium exhibited similar release rates from stainless steel and the pure metal (0.1 μgcm-2week-1). This implies that the common procedure to calculate release rates, based on the pure metals and the nominal steel composition, significantly overestimates release rates of iron and nickel from stainless steel, but not of chromium. Total release rates from seven stainless steel grades in synthetic body fluid were found to decrease with increasing alloy content in the following release rate order: grade 409 &gt;&gt; grade 430 &gt; grades 316L ≈ 201 ≈ 2205 ≈ 304 &gt; grade 310. The release rate was highly sensitive to pH of the synthetic body fluid but only slightly sensitive to stainless steel surface finish. / QC 20120217

Humans are exposed to metals and metal-containing materials daily, either conscious, e.g. using metal tools or objects, or unconscious, e.g. during exposure to airborne metal-, and metal-containing particles. The diffuse dispersion of metals from different sources in the society, and the concern related to its potential risk for adverse effects on humans have gained an increased public and governmental attention both on a national and international level. In this context, the knowledge on metal release from metallic objects or metal-containing particles is essential for health risk assessment. This thesis focuses on the study of metal release from powder particles of stainless steel and Cu-based materials exposed to synthetic body fluids mainly for simulating lung-like environments. The study comprises: i) development of a suitable experimental method for metal release studies of micron sized particles, ii) metal release data of individual alloy constituents from stainless steel powder particles of different particle sizes, and iii) Cu release from different Cu-based powder particles. In addition, the influence of chemical and physical properties of metallic particles and the test media are investigated. Selected results from Ni powder particles exposed to artificial sweat are presented for comparison. The outcome of this research is summarized through ten questions that are formulated to improve the general understanding of corrosion-induced metal release from metallic particles from a health risk perspective. A robust, reproducible, fairly simple, and straightforward experimental procedure was elaborated for metal release studies on particles of micron or submicron size. Results in terms of metal release rates show, for stainless steel powder particles, generally very low metal release rates due to a protective surface oxide film, and Fe preferentially released compared to Cr and Ni. Metal release rates are time-dependent for both stainless steel powder particles and the different Cu-containing powders investigated. The release of Cu from the Cu-containing particles depends on the chemical and compositional properties of the Cu-based material, being either corrosion-induced or chemically dissolved. Moreover, the test medium also influences the metal release process. The metal release rate increases generally with decreasing pH of the test media. However, even at a comparable pH, the release rate may be different due to differences in the interaction between the particle surface and specific media. The nature of particles is essentially different compared to massive sheet in terms of physical shape, surface composition and morphology. The surface area, and even the surface composition of metallic particles, depend on the particle size. The specific surface area of particles, area per mass, is intimately related to the particle size and has a large effect on the metal release process. Release rates increase with decreasing particle size due to a larger active surface area that takes part in the corrosion/dissolution process. The surface area that actually is active in the corrosion and metal release process (the effective area) governs the metal release process for both particles and massive sheet of metals or alloys. For particles, the effective surface area depends also on agglomeration conditions of particles during exposure. / QC 20101119

With increasing environmental awareness, the desire to protect human beings and the environment from adverse effects induced by dispersed metals has become an issue of great concern and interest. New policies, such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) within the European Community, have been implemented to reduce hazards posed by the use of chemicals on producers and downstream users. The generation of exposure assessment data and relevant test procedures able to simulate realistic scenarios are essential in such legislative actions. This doctoral study was initiated to fill knowledge gaps related to the metal release process of stainless steels. A wide range of stainless steel grades, fourteen in total, were investigated. They cover a very broad range of applications, and the focus in the thesis was to simulate a few selected exposure scenarios: precipitation, the human body and food intake. Comparisons were made between metal release from stainless steel alloys and the pure metals that constitute each stainless steel in order to explore the differences between alloys and pure metals, and to provide quantitative data on metal release rates of different alloy constituents. Because of similar surface properties between stainless steel and pure chromium, this metal exhibits similar release rates, whereas iron and nickel exhibit significantly lower release rates as alloy components than as pure metals. Detailed studies were also performed to elucidate possible relations between metal release and steel surface properties. Key parameters turned out to be chromium enrichment of the self-passivating surface film, surface roughness, the electrochemically active surface area and the microstructure of the steel substrate. The degree of metal release increased with decreasing chromium content in the surface oxide, increasing surface roughness, and increasing presence of inhomogeneities in the bulk matrix. More detailed studies were initiated to possibly correlate the nucleation of metastable pits and the extent of metal release. Evidence was given that metastable pits exist even when the stainless steel is passive, and may cause extremely short-lived bursts of released metal before the surface film repassivates again. / QC 20100810

Made available in DSpace on 2016-04-26T18:17:15Z (GMT). No. of bitstreams: 1 Gustavo Garcia da Palma.pdf: 1137319 bytes, checksum: 76b5b92accf97fed4960813084961ce6 (MD5) Previous issue date: 2008-04-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / It s very common Nowadays the use of technologies in communication processes in art. The coupling of prosthesis to the body and the cross-breeding of scenic languages happen. The analysis of these processes, most of them at least, is done under the director s, the choreographer s or the critic s perspective. The objective is the investigation of consciousness alteration for the actor based on the trance technique proposed by Jerzy Grotowski (1979, 2007), for a theater poor in technology . The hypothesis is the application of this concept in an art rich in technology: the Artmedia (MACHADO, 2002). An undisciplined and theoretical-practical methodology was used. M. McLuhan (1969, 1972), S. Pinker (1998, 2002), Y. R. G. Araújo (2005) e de P. M. Aguiar (2006) made it possible to conceive the technology as an organic/environmental process and overcome the dualism rich-poor inherent in Grotowski. The concept syntheticbody , created from the concept corpomídia (KATZ & GREINER, 2005), represents the refusal in altering itself. T. Richards (2001), R. Cohen (2004, 2003), M. Bonfitto (2002), R. Ferracini (2003), E. Barba (2006), R. Demarcy (in GUINSBURG, 2003) and others allowed a new interpretation of important theater authors like Aristóteles (1966), C. Stanislávski (1979) e J. Grotowski (op. cit.). A. Damásio (2000, 2004), S. Pinker (1998), D. C. Dennett (1997, 2006), Lakoff & Johnson (2002), R. Dawkins (2001a, 2001b), and others allowed the conception of consciousness in a healthy state, here, a parameter to identify and create altered states, which can be systemically understood from J. Vieira (2006, 2007). Consequently the actor s training system was called Alteration Procedures , and Jerry Grotowski s interpretation of the trance technique for the body could be reviewed and enlarged in high levels of technology in communication processes / É cada vez mais comum a utilização de tecnologias nos processos comunicacionais em arte. Acoplamentos de próteses ao corpo e hibridização de linguagens cênicas se sucedem. Tais processos, em sua maioria, são realizados sob a perspectiva do diretor, do coreógrafo ou do crítico de arte. Aqui é proposta uma análise pelo corpo em ação no meio. O objetivo é a investigação da alteração de consciência para o ator, com base na técnica de transe , proposta por Jerzy Grotowski (1979, 2007), para um teatro pobre em tecnologia. A hipótese é a aplicação deste conceito em uma arte rica em tecnologia: a Artemída (MACHADO, 2002). Utilizou-se de metodologia indisciplinar e teórico-prática. Autores como M. McLuhan (1969, 1972), S. Pinker (1998, 2002), Y. R. G. Araújo (2005) e P. M. Aguiar (2006) possibilitaram conceber a tecnologia como processo organismo/meio, e superar a dualidade rico-pobre inerente em Grotowski. O conceito corposintético , criado a partir do conceito corpomídia (KATZ & GREINER, 2005), representa a recusa em alterar-se. T. Richards (2001), R. Cohen (2004, 2003), M. Bonfitto (2002), R. Ferracini (2003), E. Barba (2006), R. Demarcy (in GUINSBURG, 2003) e outros permitiram a releitura de importantes autores da área teatral como Aristóteles (1966), C. Stanislávski (1979) e J. Grotowski (op. cit.). A. Damásio (2000, 2004), S. Pinker (1998), D. C. Dennett (1997, 2006), Lakoff & Johnson (2002), R. Dawkins (2001a, 2001b), e outros permitiram conceber os conceitos de consciência para ser possível identificar e criar estados alterados, entendidos sistemicamente a partir de J. Vieira (2006, 2007). Os princípios de treinamento do ator são tratados como Procedimentos de Alteração, e a leitura da técnica de transe de Jerzy Grotowski pôde ser revista e ampliada para o corpo em ambientes com altos índices de tecnologia nos processos comunicacionais

Do metal particles (including particles of pure metals, alloys, metal oxides and compounds) pose a hazard or risk to human health? In the light of this question, this thesis summarizes results from research conducted on metal particles, and describes the elaboration and implementation of an in vitro test methodology to study metal release from particles through corrosion and dissolution processes in synthetic biological media relevant for human exposure through inhalation/ingestion and dermal contact. Bioaccessible metals are defined as the pool of released metals from particles that potentially could be made available for absorption by humans or other organisms. Studies of bioaccessible metals from different metal particles within this thesis have shown that the metal release process is influenced by material properties, particle specific properties, size distribution, surface area and morphology, as well as the chemistry of synthetic biological test media simulating various human exposure scenarios. The presence of metal particles in proximity to humans and the fact that metals can be released from particles to a varying extent is the hazard referred to in the title. The bioavailable metal fraction of the released metals (the fraction available for uptake/absorption by humans through different exposure routes) is usually significantly smaller than the bioaccessible pool of released metals, and is largely related to the chemical form and state of oxidation of the released metals. Chemical speciation measurements of released chromium for instance revealed chromium to be complexed to its non-available form in simulated lung fluids. Such measurements provide an indirect measure of the potential risk for adverse health effects, when performed at relevant experimental conditions. A more direct way to assess risks is to conduct toxicological in-vitro testing of metal particles, for instance on lung cell cultures relevant for human inhalation. Induced toxicity of metal particles on lung cells includes both the effect of the particles themselves and of the released metal fraction (including bioaccessible and bioavailable metals), the latter shown to be less predominant. The toxic response was clearly influenced by various experimental conditions such as sonication treatment of particles and the presence of serum proteins. Thorough characterization of metal particles assessing parameters including chemical surface composition, degree of agglomeration in solution, size distribution, surface area and morphology was performed and discussed in relation to generated results of bioaccessibility, bioavailability and induced toxicity. One important conclusion was that neither the surface composition nor the bulk composition can be used to assess the extent of metals released from chromium-based alloy particles. These findings emphasize that information on physical-chemical properties and surface characteristics of particles is essential for an in-depth understanding of metal release processes and for further use and interpretation of bioaccessibility data to assess hazard and reduce any risks induced by human exposure to metal particles. / QC 20100803