Adding value to mine waste through recovery Au, Sb, and As: the case of auriferous tailings in the Iron Quadrangle, Brazil

From the colonial era to modern times, gold mining has played a crucial role in shaping Brazil’s economy, culture, and landscape, particularly in the Iron Quadrangle region. Therefore, resulting waste has accumulated in tailings structures, either from deactivated circuits or plants still in production. The present study reveals the potential assessed based on a set of metallurgical tests, assuming specific scenarios depending on the occurrence modes of interesting economic elements. For Au, calcination, leaching, and flotation are promising techniques to recover this element. Tests indicated that toxic elements such as Sb and As could be effectively reused in the form of glass. The generation of other products from dry cleaning techniques was not effective but promising since there was an enrichment of elements with Au, Fe, Al, and K in specific fractions.This research was funded by Fundação para a Ciência and Tecnologia (FCT) through projects UIDB/04683/2020, UIDP/04683/2020, and Nano-MINENV 029259 (PTDC/CTA-AMB/29259/2017)

The Development of a Direct Homologous Radioimmunoassay for Serum Cortisol

Peer Reviewe

Magnetic Properties of Molecular and Nanoscale Magnets

The idea of miniaturizing devices down to the nanoscale where quantum ffeffects become relevant demands a detailed understanding of the interplay between classical and quantum properties. Therefore, characterization of newly produced nanoscale materials is a very important part of the research in this fifield. Studying structural and magnetic properties of nano- and molecular magnets and the interplay between these properties reveals new interesting effects and suggests ways to control and optimize the respective material. The main task of this thesis is investigating the magnetic properties of molecular magnetic clusters and magnetic nanoparticles recently synthesized by several collaborating groups. This thesis contains two main parts focusing on each of these two topics. In the first part the fundamental studies on novel metal-organic molecular complexes is presented. Several newly synthesized magnetic complexes were investigated by means of different experimental techniques, in particular, by electron spin resonance spectroscopy. Chapter 1 in this part provides the theoretical background which is necessary for the interpretation of the effects observed in single molecular magnetic clusters. Chapter 2 introduces the experimental techniques applied in the studies. Chapter 3 contains the experimental results and their discussion. Firstly, the magnetic properties of two Ni-based complexes are presented. The complexes possess different ligand structures and arrangements of the Ni-ions in the metal cores. This difffference dramatically affffects the magnetic properties of the molecules such as the ground state and the magnetic anisotropy. Secondly, a detailed study of the Mn2Ni3 single molecular magnet is described. The complex has a bistable magnetic ground state with a high spin value of S = 7 and shows slow relaxation and quantum tunnelling of the magnetization. The third section concentrates on a Mn(III)-based single chain magnet showing ferromagnetic ordering of the Mn-spins and a strong magnetic anisotropy which leads to a hysteretic behavior of the magnetization. The last section describes a detailed study of the static and dynamic magnetic properties of three Mn-dimer molecular complexes by means of static magnetization, continuous wave and pulse electron spin resonance measurements. The results indicate a systematic dependence of the magnetic properties on the nearest ligands surrounding of the Mn ions. The second part of the thesis addresses magnetic properties of nano-scaled magnets such as carbon nanotubes fifilled with magnetic materials and carbon-coated magnetic nanoparticles. These studies are eventually aiming at the possible application of these particles as agents for magnetic hyperthermia. In this respect, their behavior in static and alternating magnetic fifields is investigated and discussed. Moreover, two possible hyperthermia applications of the studied magnetic nanoparticles are presented, which are the combination of a hyperthermia agents with an anticancer drug and the possibility to spatially localize the hyperthermia effffect by applying specially designed static magnetic fifields

Technology of cement production : issues and options for developing countries

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERINGBibliography: leaves 253-256.by Rizwan Ibrahim.M.S

Focussed MeV-Ion Micro- and Nano-Beams in the Life Sciences: Selected Applications

This work presents the development of a sub-micron nuclear microprobe for applications in the life sciences. It includes quantitative trace element analysis with sub-micron spatial resolution, 2D- and 3D-microscopy of density distributions and the targeted irradiation of living cells with counted single ions. The analytical methods base on particle induced X-ray emission spectrometry (PIXE), Rutherford backscattering spectrometry (RBS), scanning transmission ion microscopy (STIM) and STIM-tomography. The specific development of the existing nuclear microprobe LIPSION led to an improved performance of the capabilities for trace element analysis. For sub-micron analysis the spatial resolution could be improved to 300 nm at a sensitivity of about 1 µg/g for metal ions in biological matrices; for a resolution of 1 µm the sensitivity was improved to 200 ng/g (3 µmol/l). This habilitation thesis comprises a short general introduction including the motivation to utilize focussed high energy ion beams, an overview on the applications and actual research fields. The introduction is followed by the basic principles of the equipments and analytical methods. An estimation of the limits of resolution for element analytical and single ion techniques is given for the Leipzig system. Thereafter, selected studies from different research areas are presented. The first presented application is a study from environmental air pollution research. It is demonstrated that the microscopic elemental analysis of single aerosol particles can be used to assess the contributions from different sources. A further example is the analysis of the distribution of nanoparticles in skin cross-sections for a risk assessment of the applications of nanosized physical UV-filters in cosmetic products. The risk assessment is followed by the micro-analysis of trace elements, especially of bound metal ions, in brain sections on the cellular and sub-cellular level. After this the application of focussed MeV ion beams in low dose radiobiological research is presented. Finally, the analysis of 3D-density distributions by proton micro-tomography is demonstrated. A summary concludes on the applications and gives an outlook to further applications and methodological developments. The appendix comprises the relevant publications of the author.Die vorliegende Arbeit etabliert für Anwendungen in den Lebenswissenschaften den Einsatz hochfokussierter MeV-Ionenstrahlen für nuklear-mikroskopische Methoden der quantitativen Spurenelementanalyse, der 2D- und 3D-Dichtemikroskopie sowie für die gezielte Bestrahlung einzelner lebender Zellen für radiobiologische Experimente. Zur Anwendung kamen die Methoden ortsaufgelöste Protonen induzierte Röntgenfluoreszenzanalyse (particle induced X-ray emission - PIXE), Spektrometrie rückgestreuter Ionen (Rutherford backscattering spectrometry - RBS) und Rastertransmissionsionenmikroskopie (scanning transmission ion microscopy - STIM). Durch eine gezielte Weiterentwicklung des bestehenden Ionenstrahlmikroskops, der Hochenergie Ionennanosonde LIPSION, konnte die Ortsauflösung für Spurenelementanalyse auf unter 300 nm verbessert werden, beziehungsweise die Sensitivität für Metallionen in biologischen Proben auf unter 200 ng/g (3 µmol/l) bei einer Ortsauflösung von 1 µm verbessert werden. Die Habilitationsschrift umfasst eine kurze allgemeine Einleitung einschließlich der Motivation für den Einsatz fokussierter MeV-Ionenstrahlen sowie einen Überblick über die Anwendungsgebiete und aktuellen Forschungsschwerpunkte. Danach werden kurz die Grundlagen der Technik und Methoden vorgestellt, gefolgt von einer Abschätzung der A\u7fuflösungsgrenzen für Elementanalysen und Einzelionentechniken. Danach werden ausgewählte Anwendungen aus verschiedenen Forschungsgebieten vorgestellt. Das erstes Beispiel ist aus der Umweltforschung. Es wird dargestellt, wie mittels ortsaufgelöster Elementspektroskopie eine Abschätzung der Feinstaubbelastung nach Beiträgen einzelner Verursacherquellen erfolgen kann. Dann folgt als Beispiel eine ortsaufgelöste Analyse der Verteilung von Nanopartikeln aus Sonnencremes in Hautquerschnitten zur Risikoabschätzung der Anwendungen von Nanotechnologie in kosmetischen Produkten. Desweiteren werden Studien der Spurenelementverteilung, speziell der von gebundenen Metallionen, in Hirnschnitten auf zellulärer und subzellulärer Ebene erläutert. Das anschließende Beispiel erläutert die Anwendung niedriger Energiedosen in der Radiobiologie anhand des Beschusses einzelner lebender Zellen mit abgezählten einzelnen Ionen. Als letztes Beispiel wird die Anwendung hochfokussierter Ionenstrahlen für die Mikrotomographie gezeigt. Abschließend folgt eine zusammenfassende Bewertung der vorgestellten Anwendungen mit einem Ausblick auf weitere Anwendungen und methodische Entwicklungen. Der Arbeit sind die relevanten Veröffentlichungen mit Beteiligung des Autors als Anhang beigefügt

Innovations in gold extraction

The thesis takes the form of a collection of publications and patents concerning gold extraction which were presented over a period of 18 years while employed at the Anglo American Research Laboratories

Zinc based composite coatings as an alternative to electrodeposited cadmium

Cadmium coatings are currently applied to steel fasteners used in aerospace applications. At present there are growing concerns, based on cadmium's toxicity and carcinogenicity, which may lead to its eventual banning. The aim of this research, therefore, was to find a possible replacement to electrodeposited cadmium for use on aerospace fasteners. Any replacement coating system should have all of the relevant properties that make cadmium so attractive, but without its obvious shortcomings. These beneficial properties include excellent corrosion resistance in chloride containing media (such as seawater), the ability to offer sacrificial protection to steel, excellent galvanic compatibility with most aluminium alloys and an inherent lubricity. Alternatives proposed and produced in this research are electrodeposited composite coatings containing PTFE particles, based on zinc or zinc alloys. Extensive analysis was carried out in order to characterise the coatings. Composition was determined by a number of methods; gravimetric analysis was used to determine the percentage of codeposited PTFE, while X-ray and X-ray wavelength energy dispersive analysis were used to determine the percentage of alloy element present in these coatings. Coating morphology was investigated by scanning electron microscopy. The sacrificial corrosion performance of each coating in relation to steel was studied using neutral salt-spray tests, while linear polarisation resistance tests gave an indication of their barrier corrosion properties. Galvanic compatibility of the coatings with aerospace grade aluminium alloys was investigated using a zero resistance ammeter. Two different tribological tests, an inclined plane test and a reciprocating wear test, were used to determine the coefficient of friction for the coatings. Finally, linear sweep voltammetry was used to compare the kinetics of electrodeposition from dilute solutions and corrosion in aqueous media for each of the coating systems. The composite coatings were found to offer either similar or slightly reduced corrosion performance to conventional zinc and zinc alloy coatings, but were inferior to commercially electrodeposited cadmium. However, the tribological properties of these coatings demonstrated a marked improvement over cadmium

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 118

This special bibliography lists 338 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1973