Дисертації: "METALLIC AND INORGANIC"

1

To, Theany. "Fracture toughness and fracture surface energy of inorganic and non-metallic glasses." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S013/document.

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La ténacité et l’énergie de surface de fracture de verres, de vitrocéramiques et de composites à matrice en verre ont été étudiées. Tout d'abord, un test de flexion bi-axiale (configuration anneau/anneau) a été réalisé sur des verres de silice et des verre-à-vitres avec différentes conditions de surface afin d’identifier la relation entre le défaut de surface, la résistance et la ténacité du verre. Ensuite, trois méthodes d’expérimentation ont été mises en œuvre, principalement la méthode de poutre de flexion à pré-entaille droit (SEPB), la méthode de la poutre entaillée en chevron (CNB) et la méthode de la poutre avec indentations Vickers (VIF), afin de déterminer la ténacité de quatre verres produits industriellement et de déterminer les avantages et les inconvénients des différents méthodes sélectionnées. La méthode qui est apparue la plus fiable et auto-cohérente, la méthode SEPB (Single Edge Precrack Beam), a été appliquée à la détermination de la ténacité de nombreux verres et vitrocéramiques, afin d’étudier l’influence de la composition et de la microstructure sur les caractéristiques de fissuration (KIC et énergie de fissuration, γ). Enfin, l’influence de la température et de l'environnement sur la ténacité a été étudiée à l'aide de la méthode SEPB. Deux verres d'oxyde ont été testés à des températures élevées et avec une vitesse de charge de 10 MPa∙√m/s, une température de transition de 1,11Tg a été trouvée. Quatre autres verres d'oxyde ont été testés en environnement inerte et les mêmes valeurs de ténacité ont été obtenues à partir de deux vitesses de charge (100 fois) différentes
Fracture toughness and fracture surface energy of commercial and laboratory glasses, glass-ceramics and glass matrix composites have been studied. First, bi-axial bending test (RoR configuration) was performed on fused silica and window float glasses with different surface conditions to identify the relationship between the surface flaw, the strength and fracture toughness. After, three experiment methods, mainly single-edge precracked beam (SEPB), chevron-notched beam (CNB) and Vickers indentation fracture (VIF) were performed to determine the fracture toughness of four commercial known glasses and to determine the advantages and inconveniences of the different selected methods. The method that is appeared as the most reliable and self-consistent, the SEPB (Single Edge Precrack Beam) method, was applied to determine the toughness of the large amount of glasses and glass-ceramics, to study the influence of the composition and the microstructure on the characteristics of cracking (KIC and fracture energy, γ). Last but not least, the influence of the temperature and environment on the fracture toughness was studied by means of the SEPB method. Two oxide glasses were tested in elevated temperatures and with the loading rate of 10 MPa∙√m/s, a transition temperature of 1.11Tg was found. Four other oxide glasses were tested in the inert environment and the same fracture toughness values were obtained from (100 times) two different cross-head speeds

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2

Smith, Sarah. "Synthesis and Characterization of Metallic Nanoparticles for Catalytic Applications." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4803.

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In recent years, research has focused on reducing the cost of catalysts in a variety of ways including using less expensive materials, improving the synthetic method, and increasing the catalytic activity, recovery, and recyclability. Typically with nanoparticles, the size, shape, composition, and surface coating have an effect on catalytic activity.1-2 In this work, we focused on reducing the cost of precious metal based catalysts by altering the synthetic methods. One way to lower the cost of synthesizing precious metal nanoparticles is by debasing the precious metal with a second cheaper more abundant metal. CuPd nanoparticles were synthesized in oleylamine and displayed catalytic activity in several cross-coupling reactions. Due to copper being present in the nanoparticle, a copper halide co-catalyst was not needed for Sonogashira cross coupling to be successful.3 While this method produced reactive catalysts, low product yield hinders its application for industry. Solution based synthesis of metallic nanoparticles typically require long reaction times and high temperatures, which make large scale production of nanoparticles on an industrial scale difficult.4-5 The use of continuous flow microreactors provides greater control of synthetic parameters, leading to lower batch-to-batch variability and increasing the efficient of heat and mass transfer and have been applied to the synthesis of metals, semiconductors, zeolites, organic compounds, and semiconductors.5-7 To compare continuous flow methods to benchtop reactions, a well-characterized benchtop reaction synthesizing Cu@Ni core/shell nanoparticles was successfully transferred to a flow reactor set-up. Cu@Ni nanoparticles were synthesized using a capillary microreactor in under 1 minute compared to the 1 hour reaction on benchtop with similar properties in a green solvent.2 The Cu@Ni nanocomposites were active towards the Fischer Tropsch reaction.8 2 nm platinum nanoparticles and platinum bimetallic alloys were synthesized in water using a capillary microwave flow reactor. Investigations showed the nanoparticles were activity toward hydrogenation of octene. With further development, continuous flow synthesis of metallic nanoparticles can be applied to the synthesis of a wide variety of catalysts on an industrial scale. Continuous flow methods provide greater control of reaction parameters, increased safety by reacting smaller volumes of chemicals at a given time, and decreasing the batch-to-batch variability.

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3

Veitch, Paul M. "A study of organo-metallic compounds containing transition and main group elements with mixed and thio ligands." Thesis, Edinburgh Napier University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328837.

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4

Brennan, Daniel P. "Small molecule and polymer templating of inorganic materials." Diss., Online access via UMI:, 2006.

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5

Han, Qi. "Chemically modified electrodes with inorganic films of noble metal complexes and metal oxides : preparation, characterization and applications /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202002%20HAN.

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6

Di, Pietro Patrizia. "Hybrid organic-inorganic nanomaterials for applications at the biointerfaces." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3843.

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In the last few years, the application of nanomaterials (NMs) as theranostic devices, which combine diagnostic and therapeutic features, has gained a tremendous interest and development. Still, the major challenge is the understanding of the many and often complex processes that occur during the interaction of biological compounds with nanomaterials, in order to modulate their responses to the fixed target. A fine development of such smart nanosystems could occur only by a critical control of chemical/physical properties of NMs at the biological interfaces. According to such premises, this thesis deals with the investigation of NMs at the biointerfaces for potential theranostic applications. Specifically, the work has been addressed to the synthesis and characterization of several inorganic and organic nanomaterials, including gold and silver nanoparticles, hydroxyapatite, graphene and graphene oxide nanosheets tailored at the surface with stimuli-responsive polymers (polyacrylate and/or polyacrylamide) or specific chemical functionalities (amine functionalisation, sulphur functionalisation). As to the biomolecular counterpart, the performed study involved proteins (ferritin and albumin), drugs (curcumin), peptides mimicking proteins of relevant biomedical interest (such as RGD - the cell adhesive sequence of several extracellular matrix proteins-, neurotrophin peptides, fragments of the vascular endothelial growth factor), artificial membranes (lipid liposomes and supported lipid bilayers), and cells (neuroblastoma, endothelial cells, retinal pigment epithelial cells). The hybrid nano-bio-interface between the chosen NMs and biomolecules was scrutinized by a multi-technique approach, which relies on various physico-chemical spectroscopic (UV-visible, FT-IR, RAMAN, X-ray photoelectron spectroscopy), microscopic (atomic force microscopy, scanning electron microscopy, transmission electron microscopy, laser scanning confocal microscopy) and spectrometric (Time-of-Flight secondary ion mass spectrometry) methods. The research methodology used was interdisciplinary as well as the performed research, also including some biological assays on cell viability, nanoparticle internalisation by cellular uptake and nanotoxicity. The obtained results suggest promising applications for further development of these smart nanosystems for theranostic purposes.

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7

Matencio, Lloberas Sonia. "An STM/FM-AFM investigation of selected organic and inorganic 2D systems on metallic surfaces." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/347213.

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Organic/inorganic interfaces play a key role in organic electronic devices such as organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). In these interfaces crucial processes such as charge injection or extraction take place. Improving the performance of these devices has the potential to result in more efficient sources of lighting, printable electronics, and highly scalable solar energy harvesting. With this aim, a solid understanding at atomic level of the structural and electronic properties of organic/inorganic interfaces is needed. The research presented in this thesis is based on scanning probe microscopies which are powerful techniques to probe and manipulate the electronic and structure at atomic scale. The structural and electronic properties of selected organic and inorganic 2D systems on metallic surfaces have been investigated by a combined scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM) in ultra-high vacuum conditions and at room temperature. The combination of these local probe techniques permits elucidating the interface structure at atomic level and disentangle electronic from topographic information. Particular attention has been dedicated to the measure and interpretation of the local work function. Cuprous oxide (Cu2O) is an intrinsic p-type semiconductor. Copper oxide ultrathin films have been suggested to be candidates as low resistance electrodes, catalysts, sensing materials and semiconductor materials for solar cell transformation. However the properties of ultrathin film may differ from those of the bulk material. With the aim of increasing the actual knowledge, an atomic thin film of copper oxide has been grown on Cu(111) by air-enriched argon sputtering plus annealing. Several structures have been found and the local work function has been evaluated by contact potential difference and distance spectroscopies. Its structural and electronic properties are presented in Chapters 5 and 6. Several organic molecules have been investigated on different surfaces: perylene-3,4,9,10-tetracarboxylic anhydride (PTCDA), diindenoperylene (DIP) and chloroaluminum phthalocyanine (ClAlPc). All of them are small pi-conjugated molecules that have been grown by molecular beam deposition and are served as model systems for a basic understanding of organic/inorganic interfaces. The choice of the selected molecules has been motivated by the distinct chemical and physical properties: PTCDA is a perylene derivate molecule with two anhydride end groups that has an electrical quadrupole moment and forms ordered films by hydrogen bonding, ClAlPc is a phthalocyanine that has a dipole moment perpendicular to the pi-plane of the molecule and DIP is another perylene derivate that is composed only by carbon and hydrogen atoms and forms films only by van der Waals interaction. The structural and electronic properties of a monolayer of PTCDA on Si(111)7x7 and AgSi(111) have been studied and are presented in Chapter 7. A monolayer of DIP on the Cu(111) surface and a monolayer and bilayer of ClAlPc on Au(111) are shown in Chapter 8 and Chapter 9, respectively. The final structure of these molecules on the surfaces is a competition between intermolecular and molecule-substrate forces. In the organic/metal interface many complex processes can occur such as charge transfer, charge rearrangement and push back effect, affecting the work function in a non trivial way what has been evaluated in all the mentioned systems.
En los dispositivos basados en semiconductores, las interfases entre material metálico y material semiconductor juegan un papel importante en el funcionamiento final de dichos dispositivos. Algunos ejemplos de dispositivos son las celdas solares, los diodos emisores de luz y los transistores de efecto campo. En las interfases metal/semiconductor se producen muchos de los procesos fundamentales para el correcto funcionamiento de éstos, como la inyección de carga o la separación de excitones. La optimización de dichos procesos requiere un sólido conocimiento a nivel atómico de las interfases desde un punto de vista estructural y electrónico. Por consiguiente, en esta tesis se han estudiado una serie de sistemas bidimensionales orgánicos e inorgánicos crecidos sobre diferentes superficies metálicas mediante microscopía de sonda próxima, una de las técnicas más potentes en el campo de la nanotecnología. Concretamente se ha utilizado un microscopio combinado de efecto túnel (STM) y de fuerzas atómicas (AFM), en condiciones de ultra alto vacío y a temperatura ambiente. Capas delgadas de óxido de cobre (Cu2O) han sido ampliamente utilizadas por sus óptimas propiedades en catálisis y como material semiconductor en celdas solares. Con el fin de estudiar las propiedades estructurales y electrónicas, se han crecido capas ultra delgadas (un átomo de grosor) de Cu2O sobre una superficie de cobre (111). Diferentes técnicas han sido utilizadas para su caracterización estructural y electrónica. Por otro lado, otro de los materiales semiconductores utilizados en el desarrollo de futuras celdas solares son capas finas formadas por moléculas orgánicas semiconductoras. A pesar de que se podrían utilizar muchas moléculas para la fabricación de dispositivos orgánicos, las moléculas pequeñas conjugadas son especialmente interesantes debido al bajo peso molecular, su estabilidad ante la polimerización y ante la descomposición térmica. Dichas moléculas pueden ser sublimadas en condiciones de ultra alto vacío mediante crecimiento epitaxial por haces de moléculas orgánicas. En el transcurso de esta tesis, varias moléculas orgánicas han sido crecidas sobre diferentes superficies metálicas: perileno tetracarboxílico dianhídrido (PTCDA), diindenoperileno (DIP) y ftalocianina de cloro y aluminio (ClAlPc). Su caracterización estructural y la medida e interpretación de la función de trabajo local se han presentado en esta tesis.

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8

Gao, Xiaonan. "Sol-Gel Assembly of Metal Nanostructures into Metallic Gel Frameworks and Their Applications." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4319.

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The advent of nanoscience and nanotechnology has sparked many research forefronts in the creation of materials with control over size, shape, composition, and surface properties.1,2 However, for most of the applications, nanoscale materials need to be assembled into functional nanostructures that exhibit useful and controllable physical properties. Therefore, numerous efforts on the assembly of nanoparticles (NPs) using organic ligands, polymers and polyelectrolytes have been reported.3,4 However, the interactions between NPs are mediated by intervening ligands, which are detrimental to charge transport and limit the thermal stability. Hence, developing a new method to produce solid state nanostructures with direct NP linkage has become a significant challenge. To avoid the bridging ligands and improve the conductivity of NP based solid state structures, a novel strategy has been developed in which colloidal NPs undergo condensation to wet “jello-like” hydrogel with direct interfacial linkage. Then hydrogels can be dried supercritically to produce aerogels.5 Resultant nanostructures exhibit low densities, large open interconnected pores, and high internal surface areas and are containing entirely of colloidal metal NPs.6 Since noble metal NPs have been widely used in applications such as catalysts, sensors, and novel electrochemical device components, we herein expanded the sol-gel method to noble metal NPs to produce a new class of metal aerogels. In the dissertation, the synthesis of hollow Ag hollow NPs, Au/Ag alloy NPs, and Au/Pt/Ag alloy hollow NPs with tunable sizes and physical properties, and their oxidative-assembly into high-surface-area, mesoporous, self-supported gel framework has been achieved. The gelation kinetics have been controlled by tuning the oxidant/thiolate molar ratio that governs the rate of NP condensation, which in turn determines the morphology, optical transparency, surface area, and porosity of the gel frameworks. These low-density mesoporous nano-architectures displaying optical transparency or opacity, enormously surface area, and interconnected meso-to-macro pore structure are promising candidates for catalytic, electrocatalytic, and SERS-based sensing applications. The SERS activity of Au/Ag alloy aerogels has been studied and significant signal enhancement was achieved. The performance of the Au/Pt/Ag aerogel towards methanol oxidation reaction has been studied via cyclic voltammetry and significant electro-catalytic activity was observed.

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9

Peterson, Alisha D. "Synthesis and Characterization of Novel Nanomaterials: Gold Nanoshells with Organic- Inorganic Hybrid Cores." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3612.

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Gold nanoshells, a material generally composed of a core of silica surrounded by a thin shell of gold, are of great interest due to their unique and tunable optical properties. By varying the shell thickness and core size, the absorption and scattering properties are greatly enhanced. The nanoshells can be made to absorb or scatter light at various regions across the electromagnetic spectrum, from visible to the near infrared. The ability to tune the optical properties of nanoshells allows for their potential use in many different areas of research such as optical imaging, tumor ablation, drug delivery, and solar energy conversion. The research in this thesis focused on the synthesis and characterization of two novel gold nanoshell materials containing thermally-responsive, organic-inorganic hybrid layers. One type of material was based on a two-layer particle with a thermally responsive hybrid core of N-isopropylacrylamide (NIPAM) copolymerized with 3-(trimethoxysilyl)propyl methacrylate (MPS) that was then coated with a thin layer of gold. The second material was a three-layer particle with a silica core, a thermally responsive copolymer of NIPAM and MPS middle layer and an outer shell of gold. Various techniques were used to characterize both materials. Transmission electron microscopy (TEM) was used to image the particles and dynamic light scattering (DLS) was used to determine particle size and the temperature response. Additionally, UV-Vis spectroscopy was used to characterize the optical properties as a function of temperature.

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10

Yucelen, Gulfem Ipek. "Formation and growth mechanisms of single-walled metal oxide nanotubes." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44796.

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Single-walled metal oxide nanotubes have emerged as an important class of 'building block' materials for molecular recognition-based applications in catalysis, separations, sensing, and molecular encapsulation due to their vast range of potentially accessible compositions and structures, and their unique properties such as well-defined wall structure and porosity, tunable dimensions, and chemically modifiable interior and exterior surfaces. However, their widespread application will depend on the development of synthesis processes that can yield structurally and compositionally well-controlled nanotubes. Moreover, such processes should be amenable to scale-up and preferably operate via benign chemistries under mild conditions. There is currently very little knowledge on the molecular-level 'design rules' underlying the engineering of such materials. The capability to engineer single-walled tubular materials would lead to a range of structures, with novel properties relevant to diverse applications. In this thesis, main objectives are to discover the first molecular-level mechanistic framework governing the formation and growth of single-walled metal-oxide nanotubes, apply this framework to demonstrate the engineering of nanotubular materials of controlled dimensions, and to progress towards a quantitative multiscale understanding of nanotube formation. The class of aluminosilicate (AlSiOH)/germanate (AlGeOH) nanotubes are of particular interest to us, and serve as the exemplar materials for single-walled metal oxide nanotubes. They can be synthesized in pure form from inexpensive and easily accessible reactants at low temperatures (95 ˚C) from aqueous solutions. The synthesis of nanotubes occurs on a time-scale of hours to days, making them an ideal model system to study the nanotube formation mechanism. In Chapter 2, the identification and elucidation of the mechanistic role of molecular precursors and nanoscale (1-3 nm) intermediates with intrinsic curvature, in the formation of single-walled aluminosilicate nanotubes is reported. The structural and compositional evolution of molecular and nanoscale species over a length scale of 0.1-100 nm, are characterized by electrospray ionization (ESI) mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. DFT calculations revealed the intrinsic curvature of nanoscale intermediates with bonding environments similar to the structure of the final nanotube product. It is shown that curved nano-intermediates form in aqueous synthesis solutions immediately after initial hydrolysis of reactants at 25 ˚C, disappear from the solution upon heating to 95 ˚C due to condensation, and finally rearrange to form ordered single-walled aluminosilicate nanotubes. Integration of all results leads to the construction of the first molecular-level mechanism of single-walled metal oxide nanotube formation, incorporating the role of monomeric and polymeric aluminosilicate species as well as larger nanoparticles. Then, in Chapter 3, new molecular-level concepts for constructing nanoscopic metal oxide objects are demonstrated. The diameters of metal oxide nanotubes are shaped with Ångstrom-level precision by controlling the shape of nanometer-scale precursors. The subtle relationships between precursor shape and structure and final nanotube curvature are measured (at the molecular level). Anionic ligands (both organic and inorganic) are used to exert fine control over precursor shapes, allowing assembly into nanotubes whose diameters relate directly to the curvatures of shaped precursors. Having obtained considerable insight into aluminosilicate nanotube formation, in Chapter 4 the complex aqueous chemistry of nanotube-forming aluminogermanate solutions are examined. The aluminogermanate system is particularly interesting since it forms ultra-short nanotubes of lengths as small as ~20 nm. Insights into the underlying important mechanistic differences between aluminogermanate and aluminosilicate nanotube growth as well as structural differences in the final nanotube dimensions are provided. Furthermore, an experimental example of control over nanotube length is shown, using the understanding of the mechanistic differences, along with further suggestions for possible ways of controlling nanotube lengths. Ultimately, it is desired to produce the single-walled aluminosilicate nanotubes on a larger scale (e.g., kilogram or ton scales) for technological application. However, a quantitative multiscale understanding of nanotube growth via a detailed growth model, is critical to be able to predict and control key properties such as the length distribution and concentration of the nanotubes. Such a model can then be used to design liquid-phase reactors for scale-up of nanotube synthesis. In Chapter 5, a generalized kinetic model is formulated to describe the reactions leading to formation and growth of single-walled metal oxide nanotubes. This model is capable of explaining and predicting the evolution of nanotube populations as a function of kinetic parameters. It also allows considerable insight into meso/microscale nanotube growth processes. For example, it shows that two different mechanisms operate during nanotube growth: (1) growth by precursor addition, and (2) by oriented attachment of nanotubes to each other. In Chapter 6, a study of the structure of the nanotube walls is presented. It has usually been assumed in the literature that the nanotube wall is free of defects. A combination of 1H-29Si and 1H-27Al FSLG-HETCOR, 1H CRAMPS, and 1H-29Si CP/MAS NMR experiments were employed to evaluate the proton environments around Al and Si atoms during nanotube synthesis and in the final structure. The HETCOR experiments allowed to track the evolving Si and Al environments during the formation of the nanotubes from precursor species, and relate them to the Si and Al coordination environments found in the final nanotube structure. The 1H CRAMPS spectra of dehydrated aluminosilicate nanotubes revealed the proton environments in great detail. Integration of all the NMR results allows the structural assignment of all the chemical shifts and the identification of various types of defect structures in the aluminosilicate nanotube wall. In particular, five main types of defect structures are identified arising from specific atomic vacancies in the nanotube structure. It is estimated that ~16% of Si atoms in the nanotube inner wall are involved in a defect structure. The characterization of the detailed structure of the nanotube wall is expected to have significant implications for its chemical properties and applications. Chapter 7 contains concluding remarks, as well as suggestions for future directions in the engineering of single-walled nanotube materials.

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11

SRIVASTAVA, AMIT KUMAR. "STUDY ON THE BEHAVIOUR OF GLASS FIBRE REINFORCED CONCRETE." Thesis, DELHI TECHNOLOGICAL UNIVERSITY, 2021. http://dspace.dtu.ac.in:8080/jspui/handle/repository/18841.

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It is a well known fact that the tensile strength of concrete is very less in comparison to its compressive strength. Addition of fibre improves the tensile strength of concrete and improves various other properties and is called Fibre Reinforced Concrete. Different types of fibres are available which are added in concrete such as Steel fibre, Carbon fibre, Aramid, asbestos, natural fibres etc. Among various types of fibres used in preparation of Fibre Reinforced concrete, Glass fibre comes under the category of metallic and inorganic type.In this thesis, experimental investigation was carried out to study the effect of glass fibre on concrete. About 30 cubes, 30 beans, 30 cylinders were casted and cured at varying fibre content of 0%, 0.5%, 1.0%, 1.5%, & 2.0%. Various Destructive test such as Compressive strength test, Flexural Strength test, Split cylinder test andnon destructive test such as Rebound hammer test and Ultrasonic pulse velocity test were carried out on the specimen with varying fibre content. Compressive strength, flexural strength, split tensile strength all were found to increase with increase in fibre content. Maximum strength was gained at a fibre content of 1.5%. Rebound hammer test and Ultrasonic pulse velocity test were conducted to check for the effect of fibre content on test results. Results obtained from rebound hammer were compared to actual cube compressive strength and was found to be in correlation with the destructive test. The concrete quality was assessed using Ultrasonic pulse velocity test. UPV readings showed that the concrete casted were mostly found in good quality.

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12

Zhou, Tianhao. "Development of a novel ion eluting copolymer network for osteogenic applications." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/development-of-a-novel-ion-eluting-copolymer-network-for-osteogenic-applications(b58d4681-4711-414b-8bec-15d6018bb9c3).html.

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The current clinical treatment for bone deficiencies in clinics includes autografts, allografts and bone graft substitutes. All these treatments, however, still have various limitations. Therefore, in this project, we aim to design, synthesise and characterise a new series of novel polymer networks (PNs) to promote bone formation and offer a new therapeutic solution. An innovative polymerisation technique was used to synthesise the novel polymer-based materials. Various lactone monomers were applied with layered double hydroxides (LDHs) as the initiator for the polymerisation. Copolymerisation was used to control the final product degradation rate, microstructure and biocompatibility. SEM and XRD were used to confirm the formation of the 3D polymer microstructure, PNs indicated interconnected fibrous microstructure (thickness of the fibre ranged from 50-150 nm). Up to 90% polymer yield was achieved using thermogravimetric analysis. Both 1H and 13C nuclear magnetic resonance (NMR) were used to understand the effects of monomer combinations in the polymerisation. The effects of the materials on osteosarcoma cell line Saos-2 were investigated. Representative material compositions and their determined mass concentrations were applied using osteogenic culture medium with Saos-2. The PNs have indicated enhanced osteogenesis using varied assays. A poly(lactide-co-caprolactone) PN (monomer mass ratio 1:1) at 6.25 mg/ml, in particular, resulted in enhanced alkaline phosphate activity not only in growth medium but also in osteogenic medium. Moreover, it indicated the highest bone nodule production in area percentage compared to the other PN samples using Saos-2. Mg-substituted calcified extracellular matrix was formed by the use of PN materials. Therefore, this novel PN could have the possibility to be used as an acellular scaffold or a sprinkle-on powder local to defect site to enhance bone formation in vivo. In addition, this novel technology could be used as a scaffold for tissue engineering.

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13

Lai, Joshua. "Synthesis and characterization of Prussian red derived microparticles for the heterogeneous photo-fenton oxidation of azo-type textile dyes as pollutants." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/886.

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Inorganic colloidal synthesis, without a doubt, lies at the foundation of many contemporary areas of nanoscience and nanotechnology. At the advent of the 21st century, much progress has been made in the size, shape / morphological control and surface engineering of metal oxides resulting in a diverse library of macroscopic crystal architectures with well-defined surface properties. In this thesis, we start by introducing the self-assembly of the iron(oxy-, hydro-)xide while briefly reviewing some fundamental concepts of solid-state chemistry. Specific information on the family of iron oxide and iron(oxy-, hydro-)xide, as relevant to crystalline phase control, has been highlighted to direct our discussion of the synthesis of diverse crystal morphologies. Furthermore, we briefly underline and discuss the kinetic and thermodynamic control of colloidal crystal morphologies through reasonably established knowledge of anisotropic growth rates in the perspective of iron oxides' facets or crystalline planes. Lastly, we review the state-of-the-art wet chemical synthetic approaches, while using different iron(oxy-, hydro-)xide crystals as examples, for the purpose of explaining our synthetic work of choice. The main work of this thesis is entirely focused on the "facile synthesis and fine morphological tuning of branched hematite (??-Fe2O3) crystals for photodegradation of azo-type dyes".. We would discuss the crucial parameters for fine morphological tuning in the context of controlling the anisotropic growth rates of branched ??-Fe2O3 crystals instead of phase transformation. In our work, we have significantly improved the synthesis of dendritic "feather-like" and "starfish-like" for their size reduced variants for use in photocatalysis.

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14

Bandara, Nilantha. "Guest intercalation into metal halide inorganic-organic layered perovskite hybrid solids and hydrothermal synthesis of tin oxide spheres." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-10312008-212759.

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15

Kane, Kenneth. "Metallic systems at the nano and micro scale: Bimetallic nanoparticles as catalysts and MCrAlY bond coats in thermal barrier coatings." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5732.

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The dissertation is split into two parts. The first part will be focused on changes in material properties found at the nanoscale, as miscibility and electronic structure can change significantly with size. The formation of classically-immiscible bimetallic nanoparticles (BNPs) becomes favorable at the nanoscale and novel catalytic properties can emerge from the bimetallic alloying. The formation of alloyed and non-alloyed BNPs is achieved through pulse laser ablation (PLA) and a significant increase in catalytic activity is observed for both. Recently discovered, the increased activity in the non-alloyed BNPs, deemed multicomponent photocatalysis, is examined and the proposed mechanism discussed. The second part of the talk will focus on thermal barrier coatings (TBCs), which are advanced, multi-layered coatings used to protect materials in high temperature environments. MCrAlY (M=Ni, Co) bond coats deposited via atmospheric plasma spray (APS) are intrinsically rough and initially the roughness provides a high surface area platform for the mechanical interlocking of the yttria stabilized zirconia (YSZ) top coat, which provides the bulk of the thermal insulation. After high temperature exposure, a protective oxide scale forms at the top coat/bond coat interface however the convex asperities of the bond coat can grow non-α-Al2O3 type oxides that can be detrimental for coating lifetime. A surface modification technique that removes the asperities while leaving intact the concavities is used to examine the role that roughness distribution has on 1100°C APS coating lifetime. Lastly, recent work validating a modelling strategy for evaluating 900°C TBC lifetimes, which can typically surpass 25 kh, is presented. Differences in coating-substrate interdiffusion behavior over 5-20 kh of 900°C exposure are discussed and reproduced with Thermo- Calc/DICTRA for three superalloys (1483, 247, X4) deposited with high velocity oxy fuel (HVOF) NiCoCrAlY coatings.

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16

Engström, Fredrik. "Mineralogical influence on leaching behaviour of steelmaking slags : a laboratory investigation." Doctoral thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26653.

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The Swedish steelmaking industry produces large amounts of by-products. In 2008, the total amount of slag produced reached approximately 1,300,000 metric tons, of which 20% was deposited. Due to its strength, durability and chemistry, steel slag is of interest in the field of construction, since it has similar or better qualities than ordinary ballast stone, which makes it a competitive construction material. However, some steel slags face an array of quality concerns that might hinder their use. These concerns generally involve the following physical and chemical properties:Volume expansion Disintegration Leaching of metalsBy controlling and modifying process parameters during slag handling in liquid state, the physical and chemical properties of steel slags can be adequately modified to obtain a high-quality product for external application. The present work was undertaken as a research project within the Minerals and Metals Recycling Research Centre, MiMeR. The major goal of this work has been to investigate how different treatment methods including hot stage processing, cooling rates, ageing time and chemical composition influence the final properties of the slag. Analysis techniques used in this investigation include: thermodynamic calculations using FactsageTM, X-ray diffraction analyses (XRD), scanning electron microscopy (SEM), leaching tests (EN12457-2/3) and thermo-gravimetric analyses (TG).The results from this study show that it is possible to control/change the properties of the final product by additions to the liquid slag, thereby changing the chemical composition, as well as by varying the rate and method of cooling. The mineralogical composition, the size of the crystals and the composition of some solid solutions are affected by the cooling rate. The solubility of elements such as chromium and molybdenum varies, probably due to their presence in different minerals. The reactivity of the investigated slag samples increases as the cooling rate increases.When steel slags are aged, the leaching properties of the materials are changed. The total leachability and the pH decrease for all the investigated samples. All elements except magnesium decrease in leachability. As the slags are aged CaCO3 is formed on the slag surfaces. The degree of carbonation differs between different slags, due to the presence of different calcium-rich minerals in the slag. In order to form CaCO3, the calcium-containing mineral must be dissolved. This means that the solubility of the calcium-containing mineral will affect the outcome of the carbonation. The rate of dissolution for six typical slag minerals was investigated in order to distinguish the difference in solubility between the different minerals. Acidic to alkaline pHs (4, 7 and 10) were selected to investigate the solubility of the minerals under conditions comparable to those prevailing in newly produced slags and the potential future pH values obtained under acid conditions. It can be concluded that all six minerals behave differently when dissolving and that the rate of dissolution is generally slower at higher pH. At pH 10, the solubility of merwinite, akermanite and gehlenite is considered slow. The dissolution of γ-Ca2SiO4 is not affected in the same way as the other minerals when the pH is changed.
Godkänd; 2010; 20101213 (fren); DISPUTATION Ämnesområde: Processmetallurgi/Process Metallurgy Opponent: Professor Pekka Taskinen, Dept. of Materials Science and Engineering, Aalto University, Finland Ordförande: Professor Bo Björkman, Institutionen för TKG, Avd för mineralteknik och metallurgi, Luleå tekniska universitet Tid: Fredag den 4 februari 2011, kl 10.00 Plats: F341, Luleå tekniska universitet

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17

Hurley, Belinda L. "Characterization and growth analysis of two types of thin films formed on copper surfaces an inorganic chromium containing film and an organic film formed via reduction of diazonium ions /." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1094253940.

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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xvi, 205 p.; also includes graphics (some col.). Includes bibliographical references (p. 196-205).

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18

Sundqvist, Jonas. "Employing Metal Iodides and Oxygen in ALD and CVD of Functional Metal Oxides." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3450.

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19

Ramesha, K. "Synthesis And Investigation Of Transition Metal Oxides Towards Realization Of Novel Materials Properties." Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/264.

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Transition metal compounds, especially the oxides, containing dn (0 ≤ n ≤ 10) electronic configuration, constitute the backbone of solid state/materials chemistry aimed at realization of novel materials properties of technological importance. Some of the significant materials properties of current interest are spin-polarized metallic ferromagnetism, negative thermal expansion, second harmonic nonlinear optical (NLO) susceptibility, fast ionic and mixed electronic/ionic conductivity for application in solid state batteries, and last but not the least, high-temperature superconductivity. Typical examples for each one of these properties could be found among transition metal oxides. Thus, alkaline-earth metal (A) substituted rare-earth (Ln) manganites, Lnı.xAxMnΟ3, are currently important examples for spin-polarized magnetotransport, ZrV2O7 and ZrW2O8 for negative thermal expansion coefficient, KTiOPO4 and LiNbO3 for second harmonic NLO susceptibility, (Li, La) TiO3 and LiMn2O4 for fast-ionic and mixed electronic/ionic conductivity respectively, and the whole host of cuprates typified by YBa2Cu3O7 for high Tc superconductivity. Solid state chemists constantly endeavour to obtain structure-property relations of solids so as to be able to design better materials towards desired properties. Synthesis coupled with characterization of structure and measurement of relevant properties is a common strategy that chemists adopt for this task. The work described in this thesis is based on such a broad-based chemists' approach towards understanding and realization of novel materials properties among the family of metal oxides. A search for metallic ferro/ferrimagnetism among the transition metal perovskite oxides, metallicity and possibility of superconductivity among transition-metal substituted cuprates and second order NLO susceptibility among metal oxides containing d° cations such as Ti(IV), V(V) and Nb(V) - constitute the main focus of the present thesis. New synthetic strategies that combine the conventional ceramic approach with the chemistry-based 'soft1 methods have been employed wherever possible to prepare the materials. The structures and electronic properties of the new materials have been probed by state-of-the art techniques that include powder X-ray diffraction (XRD) together with Rietveld refinement, electron diffraction, thermogravimetry, measurement of magnetic susceptibility (including magnetoresistance), Mossbauer spectroscopy and SHG response (towards 1064 nm laser radiation), besides conventional analytical techniques for determination of chemical compositions. Some of the highlights of the present thesis are: (i) synthesis of new mixed valent [Mn(III)/Mn(IV)] perovskite-type manganites, ALaMn2O6-y (A = K, Rb) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr) that exhibit ferromagnetism and magnetoresistance; (ii) investigation of a variety of ferrimagnetic double-perovskites that include ALaMnRuO6 (A = Ca, Sr, Ba) and ALaFeVO6 (A = Ca, Sr) and A2FeReO6 (A = Ca, Sr, Ba) providing new insights into the occurrence of metallic and nonmetallic ferrimagnetic behaviour among this family of oxides; (iii) synthesis of new K2NiF4-type oxides, La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe, Ru) and investigation of Cu-O-M interaction in two dimension and (iv) identification of the structural rnotif(s) that gives rise to efficient second order NLO optical (SHG) response among d° oxides containing Ti(IV), V(V), Nb(V) etc., and synthesis of a new SHG material, Ba2-xVOSi2O7 having the fresnoite structure. The thesis consists of five chapters and an appendix, describing the results of the investigations carried out by the candidate. A brief introduction to transition metaloxides, perovskite oxides in particular, is presented in Chapter 1. Attention is focused on the structure and properties of these materials. Chapter 2 describes the synthesis and investigation of two series of anion-deficient perovskite oxides, ALaMn2O6-y (A = K, Rb, Cs) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr). ALaMn2O6-y (A = K, Rb, Cs) series of oxides adopt 2 ap x 2 ap superstructure for K and Rb phases and √2 av x √2 ap x 2 ap superstructure (ap = perovskite subcell) for the Cs phase. Among ALaBMn3O9-y phases, the A = Na members adopt a new kind of perovskite superstructure, ap x 3 ap, while the A = K phases do not reveal an obvious superstructure of the perovskite. All these oxides are ferromagnetic (Tc ~ 260-325 K) and metallic exhibiting a giant magnetoresistance behaviour similar to alkaline earth metal substituted lanthanum manganites, Lai_xAxMnO3. However, unlike the latter, the resistivity peak temperature Tp for all the anion-deficient manganites is significantly lower than Tc. In Chapter 3, we have investigated structure and electronic properties of double-perovskite oxides, A2FeReO6 (A = Ca, Sr and Ba). The A = Sr, Ba phases are cubic (Fm3m) and metallic, while the A = Ca phase is monoclinic (P2yn) and nonmetallic. All the three oxides are ferrimagnetic with Tcs 315-385 K as reported earlier. A = Sr, Ba phases show a negative magnetoresistance (MR) (10-25 % at 5 T), while the Ca member does not show an MR effect. 57Fe Mossbauer spectroscopy shows that iron is present in the high-spin Fe3+ (S = 5/2) state in Ca compound, while it occurs in an intermediate state between high-spin Fe2+ and Fe3+ in the Ba compound. Monoclinic distortion and high covalency of Ca-O bonds appear to freeze the oxidation states at Fe+3/Re5+ in Ca2FeRe O6, while the symmetric structure and ionic Ba-O bonds render the FeReO6 array highly covalent and Ba2FeReO6 metallic. Mossbauer data for Sr2FeReO6 shows that the valence state of iron in this compound is intermediate between that in Ba and Ca compounds. It is likely that Sr2FeReO6 which lies at the boundary between metallic and insulating states is metastable, phase-seperating into a percolating mixture of different electronic states at the microscopic level. In an effort to understand the occurrence of metallicity and ferrimagnetism among double perovskites, we have synthesized several new members : ALaMnFeO6 (A = Ca, Sr, Ba), ALaMnRuO6 (A = Ca, Sr, Ba) and ALaVFeO6 (A = Ca, Sr) (Chapter 3). Electron diffraction reveals an ordering of Mn and Ru in ALaMnRuO6 showing a doubling of the primitive cubic perovskite cell, while ALaVFeO6 do not show an ordering. ALaMnRuOs are ferrimagnetic (Tcs ~ 200-250 K) semiconductors, but ALaVFeO6 oxides do not show a long range magnetic ordering . The present work together with the previous work on double perovskites shows that only a very few of them exhibit both metallicity and ferrimagnetism, although several of them are ferrimagnetic. For example, among the series Ba2MReO6 (M = Mn, Fe, Co, Ni), only the M = Fe oxide is both metallic and ferrimagnetic, while M = Mn and Ni oxides are ferrimagnetic semiconductors. Similarly, A2CrMoO6 (A = Ca, Sr), A2CrRe06 (A = Ca, Sr), and ALaMnRuO6 (A = Ca, Sr, Ba) are all ferrimagnetic but not metallic. While ferrimagnetism of double perovskites arise from an antiferromagnetic coupling of B and B' spins through the B-O-B' bridges, the occurrence of metallicity seems to require precise matching of the energies of d-states of B and B' cations and a high covalency in the BB'O6 array that allows a facile electron-transfer between B and B', Bn++B’m+↔B(n+1)++B’(m-1)+ without an energy cost, just as occurs in ReO3 and other metallic ABO3 perovskites. In an effort to understand the Cu-O-M (M = Ti, Mn, Fe, Ru) electronic interaction in two dimension, we have investigated K2N1F4 oxides of the general formula La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe or Ru). These investigations are described in Chapter 4. For M = Ti, only the x = 0.5 member could be prepared, while for M = Mn and Fe, the composition range is 0 < x < 1.0, and for M = Ru, the composition range is 0 < x ≤ 0.5. There is no evidence for ordering of Cu(II) and M(IV) in the x = 0.5 members. While the members of the M = Ti, Mn and Ru series are semiconducting/insulating, the members of the M = Fe series are metallic, showing a broad metal-semiconductor transition around 100 K for 0 < x ≤ 0.15 that is possibly related to a Cu(II)-O-Fe(IV) < > Cu(III)-O-Fe(III) valence degeneracy. Increasing the strontium content at the expense of lanthanum in La2-2xSr2XCui.xFexO4 for x ≤ 0.20 renders the samples metallic but not superconducting. In a search for inorganic oxide materials showing second order nonlinear optical (NLO) susceptibility, we have investigated several borates, silicates and phosphates containing /ram-connected MO6 octahedral chains or MO5 square-pyramids, where M = d°: Ti(IV), Nb(V) or Ta(V). Our investigations, which are described in Chapter 5, have identified two new NLO structures: batisite, Na2Ba(TiO)2Si4O12, containing trans-connectd TiO6 octahedral chains, and fresnoite, Ba2TiOSi2O7, containing square-pyramidal T1O5. Investigation of two other materials containing square-pyramidal TiO5, viz., Cs2TiOP2O7 and Na4Ti2Si8O22. 4H2O, revealed that isolated TiO5 square-pyramids alone do not cause a second harmonic generation (SHG) response; rather, the orientation of T1O5 units to produce -Ti-O-Ti-O- chains with alternating long and short Ti-0 distances in the fresnoite structure is most likely the origin of a strong SHG response in fresnoite. Indeed, we have been able to prepare a new fresnoite type oxide, Ba2.xVOSi2O7 (x ~ 0.5) that shows a strong SHG response, confirming this hypothesis. In the Appendix, we have described three synthetic strategies that enabled us to prepare magnetic and NLO materials. We have shown that the reaction CrO3 + 2 NH4X > CrO2 + 2 NH3 + H2O + X2 (X = Br, I), which occurs quantitatively at 120-150 °C, provides a convenient method for the synthesis of CrO2. Unlike conventional methods, the method described here does not require the use of high pressure for the synthesis of this technologically important material. For the synthesis of magnetic double perovskites, we have developed a method that involves reaction of basic alkali metal carbonates with the acidic oxides (e.g. Re2O7) first, followed by reaction of this precursor oxide with the required transition metal/transition metal oxide (e.g. Fe/Fe2O3). By this method we have successfully prepared single-phase perovskite oxides, A2FeReO6, ACrMoO6 and ALaFeVO6. We have prepared the new NLO material Ba2_xV0Si207 from Ba2VOSi2O7 by a soft chemical redox reaction involving the oxidation of V(IV) to V(V) using Br2 in CH3CN/CHCI3. Ba2V0Si207 + 1/2 Br2 > Bai.5V0Si207 + 1/2 BaBr2. The work presented in this thesis was carried out by the candidate as part of the Ph.D. training programme. He hopes that the studies reported here will constitute a worthwhile contribution to the solid state chemistry of transition metal oxides and related materials.

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20

Ramesha, K. "Synthesis And Investigation Of Transition Metal Oxides Towards Realization Of Novel Materials Properties." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/264.

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Анотація:

Transition metal compounds, especially the oxides, containing dn (0 ≤ n ≤ 10) electronic configuration, constitute the backbone of solid state/materials chemistry aimed at realization of novel materials properties of technological importance. Some of the significant materials properties of current interest are spin-polarized metallic ferromagnetism, negative thermal expansion, second harmonic nonlinear optical (NLO) susceptibility, fast ionic and mixed electronic/ionic conductivity for application in solid state batteries, and last but not the least, high-temperature superconductivity. Typical examples for each one of these properties could be found among transition metal oxides. Thus, alkaline-earth metal (A) substituted rare-earth (Ln) manganites, Lnı.xAxMnΟ3, are currently important examples for spin-polarized magnetotransport, ZrV2O7 and ZrW2O8 for negative thermal expansion coefficient, KTiOPO4 and LiNbO3 for second harmonic NLO susceptibility, (Li, La) TiO3 and LiMn2O4 for fast-ionic and mixed electronic/ionic conductivity respectively, and the whole host of cuprates typified by YBa2Cu3O7 for high Tc superconductivity. Solid state chemists constantly endeavour to obtain structure-property relations of solids so as to be able to design better materials towards desired properties. Synthesis coupled with characterization of structure and measurement of relevant properties is a common strategy that chemists adopt for this task. The work described in this thesis is based on such a broad-based chemists' approach towards understanding and realization of novel materials properties among the family of metal oxides. A search for metallic ferro/ferrimagnetism among the transition metal perovskite oxides, metallicity and possibility of superconductivity among transition-metal substituted cuprates and second order NLO susceptibility among metal oxides containing d° cations such as Ti(IV), V(V) and Nb(V) - constitute the main focus of the present thesis. New synthetic strategies that combine the conventional ceramic approach with the chemistry-based 'soft1 methods have been employed wherever possible to prepare the materials. The structures and electronic properties of the new materials have been probed by state-of-the art techniques that include powder X-ray diffraction (XRD) together with Rietveld refinement, electron diffraction, thermogravimetry, measurement of magnetic susceptibility (including magnetoresistance), Mossbauer spectroscopy and SHG response (towards 1064 nm laser radiation), besides conventional analytical techniques for determination of chemical compositions. Some of the highlights of the present thesis are: (i) synthesis of new mixed valent [Mn(III)/Mn(IV)] perovskite-type manganites, ALaMn2O6-y (A = K, Rb) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr) that exhibit ferromagnetism and magnetoresistance; (ii) investigation of a variety of ferrimagnetic double-perovskites that include ALaMnRuO6 (A = Ca, Sr, Ba) and ALaFeVO6 (A = Ca, Sr) and A2FeReO6 (A = Ca, Sr, Ba) providing new insights into the occurrence of metallic and nonmetallic ferrimagnetic behaviour among this family of oxides; (iii) synthesis of new K2NiF4-type oxides, La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe, Ru) and investigation of Cu-O-M interaction in two dimension and (iv) identification of the structural rnotif(s) that gives rise to efficient second order NLO optical (SHG) response among d° oxides containing Ti(IV), V(V), Nb(V) etc., and synthesis of a new SHG material, Ba2-xVOSi2O7 having the fresnoite structure. The thesis consists of five chapters and an appendix, describing the results of the investigations carried out by the candidate. A brief introduction to transition metaloxides, perovskite oxides in particular, is presented in Chapter 1. Attention is focused on the structure and properties of these materials. Chapter 2 describes the synthesis and investigation of two series of anion-deficient perovskite oxides, ALaMn2O6-y (A = K, Rb, Cs) and ALaBMn3O9_y (A = Na, K; B = Ca, Sr). ALaMn2O6-y (A = K, Rb, Cs) series of oxides adopt 2 ap x 2 ap superstructure for K and Rb phases and √2 av x √2 ap x 2 ap superstructure (ap = perovskite subcell) for the Cs phase. Among ALaBMn3O9-y phases, the A = Na members adopt a new kind of perovskite superstructure, ap x 3 ap, while the A = K phases do not reveal an obvious superstructure of the perovskite. All these oxides are ferromagnetic (Tc ~ 260-325 K) and metallic exhibiting a giant magnetoresistance behaviour similar to alkaline earth metal substituted lanthanum manganites, Lai_xAxMnO3. However, unlike the latter, the resistivity peak temperature Tp for all the anion-deficient manganites is significantly lower than Tc. In Chapter 3, we have investigated structure and electronic properties of double-perovskite oxides, A2FeReO6 (A = Ca, Sr and Ba). The A = Sr, Ba phases are cubic (Fm3m) and metallic, while the A = Ca phase is monoclinic (P2yn) and nonmetallic. All the three oxides are ferrimagnetic with Tcs 315-385 K as reported earlier. A = Sr, Ba phases show a negative magnetoresistance (MR) (10-25 % at 5 T), while the Ca member does not show an MR effect. 57Fe Mossbauer spectroscopy shows that iron is present in the high-spin Fe3+ (S = 5/2) state in Ca compound, while it occurs in an intermediate state between high-spin Fe2+ and Fe3+ in the Ba compound. Monoclinic distortion and high covalency of Ca-O bonds appear to freeze the oxidation states at Fe+3/Re5+ in Ca2FeRe O6, while the symmetric structure and ionic Ba-O bonds render the FeReO6 array highly covalent and Ba2FeReO6 metallic. Mossbauer data for Sr2FeReO6 shows that the valence state of iron in this compound is intermediate between that in Ba and Ca compounds. It is likely that Sr2FeReO6 which lies at the boundary between metallic and insulating states is metastable, phase-seperating into a percolating mixture of different electronic states at the microscopic level. In an effort to understand the occurrence of metallicity and ferrimagnetism among double perovskites, we have synthesized several new members : ALaMnFeO6 (A = Ca, Sr, Ba), ALaMnRuO6 (A = Ca, Sr, Ba) and ALaVFeO6 (A = Ca, Sr) (Chapter 3). Electron diffraction reveals an ordering of Mn and Ru in ALaMnRuO6 showing a doubling of the primitive cubic perovskite cell, while ALaVFeO6 do not show an ordering. ALaMnRuOs are ferrimagnetic (Tcs ~ 200-250 K) semiconductors, but ALaVFeO6 oxides do not show a long range magnetic ordering . The present work together with the previous work on double perovskites shows that only a very few of them exhibit both metallicity and ferrimagnetism, although several of them are ferrimagnetic. For example, among the series Ba2MReO6 (M = Mn, Fe, Co, Ni), only the M = Fe oxide is both metallic and ferrimagnetic, while M = Mn and Ni oxides are ferrimagnetic semiconductors. Similarly, A2CrMoO6 (A = Ca, Sr), A2CrRe06 (A = Ca, Sr), and ALaMnRuO6 (A = Ca, Sr, Ba) are all ferrimagnetic but not metallic. While ferrimagnetism of double perovskites arise from an antiferromagnetic coupling of B and B' spins through the B-O-B' bridges, the occurrence of metallicity seems to require precise matching of the energies of d-states of B and B' cations and a high covalency in the BB'O6 array that allows a facile electron-transfer between B and B', Bn++B’m+↔B(n+1)++B’(m-1)+ without an energy cost, just as occurs in ReO3 and other metallic ABO3 perovskites. In an effort to understand the Cu-O-M (M = Ti, Mn, Fe, Ru) electronic interaction in two dimension, we have investigated K2N1F4 oxides of the general formula La2-2xSr2XCui.xMxO4 (M = Ti, Mn, Fe or Ru). These investigations are described in Chapter 4. For M = Ti, only the x = 0.5 member could be prepared, while for M = Mn and Fe, the composition range is 0 < x < 1.0, and for M = Ru, the composition range is 0 < x ≤ 0.5. There is no evidence for ordering of Cu(II) and M(IV) in the x = 0.5 members. While the members of the M = Ti, Mn and Ru series are semiconducting/insulating, the members of the M = Fe series are metallic, showing a broad metal-semiconductor transition around 100 K for 0 < x ≤ 0.15 that is possibly related to a Cu(II)-O-Fe(IV) < > Cu(III)-O-Fe(III) valence degeneracy. Increasing the strontium content at the expense of lanthanum in La2-2xSr2XCui.xFexO4 for x ≤ 0.20 renders the samples metallic but not superconducting. In a search for inorganic oxide materials showing second order nonlinear optical (NLO) susceptibility, we have investigated several borates, silicates and phosphates containing /ram-connected MO6 octahedral chains or MO5 square-pyramids, where M = d°: Ti(IV), Nb(V) or Ta(V). Our investigations, which are described in Chapter 5, have identified two new NLO structures: batisite, Na2Ba(TiO)2Si4O12, containing trans-connectd TiO6 octahedral chains, and fresnoite, Ba2TiOSi2O7, containing square-pyramidal T1O5. Investigation of two other materials containing square-pyramidal TiO5, viz., Cs2TiOP2O7 and Na4Ti2Si8O22. 4H2O, revealed that isolated TiO5 square-pyramids alone do not cause a second harmonic generation (SHG) response; rather, the orientation of T1O5 units to produce -Ti-O-Ti-O- chains with alternating long and short Ti-0 distances in the fresnoite structure is most likely the origin of a strong SHG response in fresnoite. Indeed, we have been able to prepare a new fresnoite type oxide, Ba2.xVOSi2O7 (x ~ 0.5) that shows a strong SHG response, confirming this hypothesis. In the Appendix, we have described three synthetic strategies that enabled us to prepare magnetic and NLO materials. We have shown that the reaction CrO3 + 2 NH4X > CrO2 + 2 NH3 + H2O + X2 (X = Br, I), which occurs quantitatively at 120-150 °C, provides a convenient method for the synthesis of CrO2. Unlike conventional methods, the method described here does not require the use of high pressure for the synthesis of this technologically important material. For the synthesis of magnetic double perovskites, we have developed a method that involves reaction of basic alkali metal carbonates with the acidic oxides (e.g. Re2O7) first, followed by reaction of this precursor oxide with the required transition metal/transition metal oxide (e.g. Fe/Fe2O3). By this method we have successfully prepared single-phase perovskite oxides, A2FeReO6, ACrMoO6 and ALaFeVO6. We have prepared the new NLO material Ba2_xV0Si207 from Ba2VOSi2O7 by a soft chemical redox reaction involving the oxidation of V(IV) to V(V) using Br2 in CH3CN/CHCI3. Ba2V0Si207 + 1/2 Br2 > Bai.5V0Si207 + 1/2 BaBr2. The work presented in this thesis was carried out by the candidate as part of the Ph.D. training programme. He hopes that the studies reported here will constitute a worthwhile contribution to the solid state chemistry of transition metal oxides and related materials.

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21

Cordero, Arias Luis Eduardo [Verfasser], Aldo [Akademischer Betreuer] Boccaccini, and Sannakaisa [Akademischer Betreuer] Virtanen. "Electrophoretic deposition of organic/inorganic composite coatings on metallic substrates for bone replacement applications: mechanisms and development of new bioactive materials based on polysaccharides / Luis Eduardo Cordero Arias. Gutachter: Aldo Boccaccini ; Sannakaisa Virtanen." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1076673902/34.

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22

Gunnarsson, Rickard. "Controlling the growth of nanoparticles produced in a highpower pulsed plasma." Doctoral thesis, Linköpings universitet, Plasma och beläggningsfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-143843.

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Nanotechnology can profoundly benefit our health, environment and everyday life. In order to make this a reality, both technological and theoretical advancements of the nanomaterial synthesis methods are needed. A nanoparticle is one of the fundamental building blocks in nanotechnology and this thesis describes the control of the nucleation, growth and oxidation of titanium particles produced in a pulsed plasma. It will be shown that by controlling the process conditions both the composition (oxidationstate) and size of the particles can be varied. The experimental results are supported by theoretical modeling. If processing conditions are chosen which give a high temperature in the nanoparticle growth environment, oxygen was found to be necessary in order to nucleate the nanoparticles. The two reasons for this are 1: the lower vapor pressure of a titanium oxide cluster compared to a titanium cluster, meaning a lower probability of evaporation, and 2: the ability of a cluster to cool down by ejecting an oxygen atom when an oxygen molecule condenses on its surface. When the oxygen gas flow was slightly increased, the nanoparticle yield and oxidation state increased. A further increase caused a decrease in particle yield which is attributed to a slight oxidation ofthe cathode. By varying the oxygen flow, it was possible to control the oxidation state of the nanoparticles without fully oxidizing the cathode. Pure titanium nanoparticles could not be produced in a high vacuum system because oxygen containing gases such as residual water vapour have a profound influence on nanoparticle yield and composition. In an ultrahigh vacuum system titanium nanoparticles without significantoxygen contamination were produced by reducing the temperature of the growth environment and increasing the pressure of an argon-helium gas mixture within whichthe nanoparticles grew. The dimer formation rate necessary for this is only achievable at higher pressures. After a dimer has formed, it needs to grow by colliding with a titanium atom followed by cooling by collisions with multiple buffer gas atoms. The condensation event heats up the cluster to a temperature much higher than the gas temperature, where it is during a short time susceptible to evaporation. When the clusters’ internal energy has decreased by collisions with the gas to less than the energy required to evaporate a titanium atom, it is temporarily stable until the next condensation event occurs. The temperature difference by which the cluster has to cool down before it is temporarily stable is exactly as many kelvins as the gas temperature.The addition of helium was found to decrease the temperature of the gas, making it possible for nanoparticles of pure titanium to grow. The process window where this is possible was determined and the results presented opens up new possibilities to synthesize particles with a controlled contamination level and deposition rate.The size of the nanoparticles has been controlled by three means. The first is to change the electrical potential around the growth zone, which allows for size (diameter) control in the order of 25 to 75 nm without influencing the oxygen content of the particles. The second means is by increasing the pressure which decreases the ambipolar diffusion rate of the ions resulting in a higher growth material density. By doing this, the particle size can be increased from 50 to 250 nm, however the oxygen content also increases with increasing pressure when this is done in a high vacuum system. The last means of size control was by adding a helium flow to the process where higher flows resulted in smaller nanoparticle sizes. When changing the pressure in high vacuum, the morphology of the nanoparticles could be controlled. At low pressures, highly faceted near spherical particles were produced. Increasing the pressure caused the formation of cubic particles which appear to ‘fracture’ at higher pressures. At the highest pressure investigated, the particles became poly-crystalline with a cauliflower shape and this morphology was attributed to a lowad atom mobility. The ability to control the size, morphology and composition of the nanoparticles determines the success of applying the process to manufacture devices. In related work presented in this thesis it is shown that 150-200 nm molybdenum particles with cauliflower morphology were found to scatter light in which made them useful in photovoltaic applications, and the size of titanium dioxide nanoparticles were found to influence the selectivity of graphene based gas sensors.

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23

Fracasso, Guido <1960&gt. "Synthesis and Physical-Chemical characterization of Metallic Nanoparticles." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2895/2/Fracasso_Guido_tesi.pdf.

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The stabilization of nanoparticles against their irreversible particle aggregation and oxidation reactions. is a requirement for further advancement in nanoparticle science and technology. For this reason the research aim on this topic focuses on the synthesis of various metal nanoparticles protected with monolayers containing different reactive head groups and functional tail groups. In this work cuprous bromide nanocrystals haave been synthetized with a diameter of about 20 nanometers according to a new sybthetic method adding dropwise ascorbic acid to a water solution of lithium bromide and cupric chloride under continuous stirring and nitrogen flux. Butane thiolate Cu protected nanoparticles have been synthetized according to three different syntesys methods. Their morphologies appear related to the physicochemical conditions during the synthesis and to the dispersing medium used to prepare the sample. Synthesis method II allows to obtain stable nanoparticles of 1-2 nm in size both isolated and forming clusters. Nanoparticle cluster formation was enhanced as water was used as dispersing medium probably due to the idrophobic nature of the butanethiolate layers coating the nanoparticle surface. Synthesis methods I and III lead to large unstable spherical nanoparticles with size ranging between 20 to 50 nm. These nanoparticles appeared in the TEM micrograph with the same morphology independently on the dispersing medium used in the sample preparation. The stability and dimensions of the copper nanoparticles appear inversely related. Using the same methods above described for the butanethiolate protected copper nanoparticles 4-methylbenzenethiol protected copper nanoparticles have been prepared. Diffractometric and spectroscopic data reveal that decomposition processes didn’t occur in both the 4-methylbenzenethiol copper protected nanoparticles precipitates from formic acid and from water in a period of time six month long. Se anticarcinogenic effects by multiple mechanisms have been extensively investigated and documented and Se is defined a genuine nutritional cancer-protecting element and a significant protective effect of Se against major forms of cancer. Furthermore phloroglucinol was found to possess cytoprotective effects against oxidative stress, thanks to reactive oxygen species (ROS) which are associated with cells and tissue damages and are the contributing factors for inflammation, aging, cancer, arteriosclerosis, hypertension and diabetes. The goal of our work has been to set up a new method to synthesize in mild conditions amorphous Se nanopaticles surface capped with phloroglucinol, which is used during synthesis as reducing agent to obtain stable Se nanoparticles in ethanol, performing the synergies offered by the specific anticarcinogenic properties of Se and the antioxiding ones of phloroalucinol. We have synthesized selenium nanoparticles protected by phenolic molecules chemically bonded to their surface. The phenol molecules coating the nanoparticles surfaces form low ordered arrays as can be seen from the wider shape of the absorptions in the FT-IR spectrum with respect to those appearing in that of crystalline phenol. On the other hand, metallic nanoparticles with unique optical properties, facile surface chemistry and appropriate size scale are generating much enthusiasm in nanomedicine. In fact Au nanoparticles has immense potential for both cancer diagnosis and therapy. Especially Au nanoparticles efficiently convert the strongly adsorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. According to the about, metal nanoparticles-HA nanocrystals composites should have tremendous potential in novel methods for therapy of cancer. 11 mercaptoundecanoic surface protected Au4Ag1 nanoparticles adsorbed on nanometric apathyte crystals we have successfully prepared like an anticancer nanoparticles deliver system utilizing biomimetic hydroxyapatyte nanocrystals as deliver agents. Furthermore natural chrysotile, formed by densely packed bundles of multiwalled hollow nanotubes, is a mineral very suitable for nanowires preparation when their inner nanometer-sized cavity is filled with a proper material. Bundles of chrysotile nanotubes can then behave as host systems, where their large interchannel separation is actually expected to prevent the interaction between individual guest metallic nanoparticles and act as a confining barrier. Chrysotile nanotubes have been filled with molten metals such as Hg, Pb, Sn, semimetals, Bi, Te, Se, and with semiconductor materials such as InSb, CdSe, GaAs, and InP using both high-pressure techniques and metal-organic chemical vapor deposition. Under hydrothermal conditions chrysotile nanocrystals have been synthesized as a single phase and can be utilized as a very suitable for nanowires preparation filling their inner nanometer-sized cavity with metallic nanoparticles. In this research work we have synthesized and characterized Stoichiometric synthetic chrysotile nanotubes have been partially filled with bi and monometallic highly monodispersed nanoparticles with diameters ranging from 1,7 to 5,5 nm depending on the core composition (Au, Au4Ag1, Au1Ag4, Ag). In the case of 4 methylbenzenethiol protected silver nanoparticles, the filling was carried out by convection and capillarity effect at room temperature and pressure using a suitable organic solvent. We have obtained new interesting nanowires constituted of metallic nanoparticles filled in inorganic nanotubes with a inner cavity of 7 nm and an isolating wall with a thick ranging from 7 to 21 nm.

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24

Fracasso, Guido <1960&gt. "Synthesis and Physical-Chemical characterization of Metallic Nanoparticles." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2895/.

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Анотація:

The stabilization of nanoparticles against their irreversible particle aggregation and oxidation reactions. is a requirement for further advancement in nanoparticle science and technology. For this reason the research aim on this topic focuses on the synthesis of various metal nanoparticles protected with monolayers containing different reactive head groups and functional tail groups. In this work cuprous bromide nanocrystals haave been synthetized with a diameter of about 20 nanometers according to a new sybthetic method adding dropwise ascorbic acid to a water solution of lithium bromide and cupric chloride under continuous stirring and nitrogen flux. Butane thiolate Cu protected nanoparticles have been synthetized according to three different syntesys methods. Their morphologies appear related to the physicochemical conditions during the synthesis and to the dispersing medium used to prepare the sample. Synthesis method II allows to obtain stable nanoparticles of 1-2 nm in size both isolated and forming clusters. Nanoparticle cluster formation was enhanced as water was used as dispersing medium probably due to the idrophobic nature of the butanethiolate layers coating the nanoparticle surface. Synthesis methods I and III lead to large unstable spherical nanoparticles with size ranging between 20 to 50 nm. These nanoparticles appeared in the TEM micrograph with the same morphology independently on the dispersing medium used in the sample preparation. The stability and dimensions of the copper nanoparticles appear inversely related. Using the same methods above described for the butanethiolate protected copper nanoparticles 4-methylbenzenethiol protected copper nanoparticles have been prepared. Diffractometric and spectroscopic data reveal that decomposition processes didn’t occur in both the 4-methylbenzenethiol copper protected nanoparticles precipitates from formic acid and from water in a period of time six month long. Se anticarcinogenic effects by multiple mechanisms have been extensively investigated and documented and Se is defined a genuine nutritional cancer-protecting element and a significant protective effect of Se against major forms of cancer. Furthermore phloroglucinol was found to possess cytoprotective effects against oxidative stress, thanks to reactive oxygen species (ROS) which are associated with cells and tissue damages and are the contributing factors for inflammation, aging, cancer, arteriosclerosis, hypertension and diabetes. The goal of our work has been to set up a new method to synthesize in mild conditions amorphous Se nanopaticles surface capped with phloroglucinol, which is used during synthesis as reducing agent to obtain stable Se nanoparticles in ethanol, performing the synergies offered by the specific anticarcinogenic properties of Se and the antioxiding ones of phloroalucinol. We have synthesized selenium nanoparticles protected by phenolic molecules chemically bonded to their surface. The phenol molecules coating the nanoparticles surfaces form low ordered arrays as can be seen from the wider shape of the absorptions in the FT-IR spectrum with respect to those appearing in that of crystalline phenol. On the other hand, metallic nanoparticles with unique optical properties, facile surface chemistry and appropriate size scale are generating much enthusiasm in nanomedicine. In fact Au nanoparticles has immense potential for both cancer diagnosis and therapy. Especially Au nanoparticles efficiently convert the strongly adsorbed light into localized heat, which can be exploited for the selective laser photothermal therapy of cancer. According to the about, metal nanoparticles-HA nanocrystals composites should have tremendous potential in novel methods for therapy of cancer. 11 mercaptoundecanoic surface protected Au4Ag1 nanoparticles adsorbed on nanometric apathyte crystals we have successfully prepared like an anticancer nanoparticles deliver system utilizing biomimetic hydroxyapatyte nanocrystals as deliver agents. Furthermore natural chrysotile, formed by densely packed bundles of multiwalled hollow nanotubes, is a mineral very suitable for nanowires preparation when their inner nanometer-sized cavity is filled with a proper material. Bundles of chrysotile nanotubes can then behave as host systems, where their large interchannel separation is actually expected to prevent the interaction between individual guest metallic nanoparticles and act as a confining barrier. Chrysotile nanotubes have been filled with molten metals such as Hg, Pb, Sn, semimetals, Bi, Te, Se, and with semiconductor materials such as InSb, CdSe, GaAs, and InP using both high-pressure techniques and metal-organic chemical vapor deposition. Under hydrothermal conditions chrysotile nanocrystals have been synthesized as a single phase and can be utilized as a very suitable for nanowires preparation filling their inner nanometer-sized cavity with metallic nanoparticles. In this research work we have synthesized and characterized Stoichiometric synthetic chrysotile nanotubes have been partially filled with bi and monometallic highly monodispersed nanoparticles with diameters ranging from 1,7 to 5,5 nm depending on the core composition (Au, Au4Ag1, Au1Ag4, Ag). In the case of 4 methylbenzenethiol protected silver nanoparticles, the filling was carried out by convection and capillarity effect at room temperature and pressure using a suitable organic solvent. We have obtained new interesting nanowires constituted of metallic nanoparticles filled in inorganic nanotubes with a inner cavity of 7 nm and an isolating wall with a thick ranging from 7 to 21 nm.

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25

Apte, S. C. "The aquatic chemistry of some metalloid elements." Thesis, University of Southampton, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304812.

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26

Mazzaro, Raffaello <1988&gt. "Graphene and Semicondutor or Metallic Nanoparticles for Energy Conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/5987/1/Mazzaro_Raffaello_tesi.pdf.

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The purpose of the present PhD thesis is to investigate the properties of innovative nano- materials with respect to the conversion of renewable energies to electrical and chemical energy. The materials have been synthesized and characterized by means of a wide spectrum of morphological, compositional and photophysical techniques, in order to get an insight into the correlation between the properties of each material and the activity towards different energy conversion applications. Two main topics are addressed: in the first part of the thesis the light harvesting in pyrene functionalized silicon nanocrystals has been discussed, suggesting an original approach to suc- cessfully increase the absorption properties of these nanocrystals. The interaction of these nanocrystals was then studied, in order to give a deeper insight on the charge and energy extraction, preparing the way to implement SiNCs as active material in optoelectronic devices and photovoltaic cells. In addition to this, the luminescence of SiNCs has been exploited to increase the efficiency of conventional photovoltaic cells by means of two innovative architectures. Specifically, SiNCs has been used as luminescent downshifting layer in dye sensitized solar cells, and they were shown to be very promising light emitters in luminescent solar concentrators. The second part of the thesis was concerned on the production of hydrogen by platinum nanoparticles coupled to either electro-active or photo-active materials. Within this context, the electrocatalytic activity of platinum nanoparticles supported on exfoliated graphene has been studied, preparing an high-efficiency catalyst and disclosing the role of the exfoliation technique towards the catalytic activity. Furthermore, platinum nanoparticles have been synthesized within photoactive dendrimers, providing the first proof of concept of a dendrimer-based photocatalytic system for the hydrogen production where both sensitizer and catalyst are anchored to a single scaffold.

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27

Mazzaro, Raffaello <1988&gt. "Graphene and Semicondutor or Metallic Nanoparticles for Energy Conversion." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/5987/.

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Анотація:

The purpose of the present PhD thesis is to investigate the properties of innovative nano- materials with respect to the conversion of renewable energies to electrical and chemical energy. The materials have been synthesized and characterized by means of a wide spectrum of morphological, compositional and photophysical techniques, in order to get an insight into the correlation between the properties of each material and the activity towards different energy conversion applications. Two main topics are addressed: in the first part of the thesis the light harvesting in pyrene functionalized silicon nanocrystals has been discussed, suggesting an original approach to suc- cessfully increase the absorption properties of these nanocrystals. The interaction of these nanocrystals was then studied, in order to give a deeper insight on the charge and energy extraction, preparing the way to implement SiNCs as active material in optoelectronic devices and photovoltaic cells. In addition to this, the luminescence of SiNCs has been exploited to increase the efficiency of conventional photovoltaic cells by means of two innovative architectures. Specifically, SiNCs has been used as luminescent downshifting layer in dye sensitized solar cells, and they were shown to be very promising light emitters in luminescent solar concentrators. The second part of the thesis was concerned on the production of hydrogen by platinum nanoparticles coupled to either electro-active or photo-active materials. Within this context, the electrocatalytic activity of platinum nanoparticles supported on exfoliated graphene has been studied, preparing an high-efficiency catalyst and disclosing the role of the exfoliation technique towards the catalytic activity. Furthermore, platinum nanoparticles have been synthesized within photoactive dendrimers, providing the first proof of concept of a dendrimer-based photocatalytic system for the hydrogen production where both sensitizer and catalyst are anchored to a single scaffold.

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28

Barolo, Andrea. "Studio di catalizzatori a base di film sottili di ossidi metallici di transizione su substrato metallico monocristallino." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427523.

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This work discuss thin solid films of transition metal oxides on crystalline metal substrate morpholgy and reactivity toward gases. In particular the systems analyzed are: CoO on Pd(100), SnO on Pt(110) and NiO on Pd(100).
Questo lavoro discute in proposito di film sottili di ossidi di metalli di transizione su substrato metallico cristallino in riferimento alla loro morfologia e reattività verso i gas. In particolare i sistemi analizzati sono CoO su Pd(100), SnO su Pt(110) and NiO su Pd(100).

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29

Zanardo, Gianluigi <1980&gt. "Preparazione e reattività di Stannil complessi di metalli di transizione." Doctoral thesis, Università Ca' Foscari Venezia, 2008. http://hdl.handle.net/10579/141.

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30

Palmer, Michelle Alexandra. "The synthesis of cyclic-metallo peptides related to copper-zinc centre of superoxide dismutase." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286536.

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31

Bonsignore, Riccardo. "Studio dell'interazione di DNA con complessi di metalli di transizione." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/91025.

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32

Tang, Christian C. "Structure and Activity of Metallo-Peptides." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6961.

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Metal ions are ubiquitously found in all living systems and play vital roles in supporting life forms by performing an array of biological activities. Such biological activities include binding and transforming organic molecules, and also acting as active centers and cofactors for catalysis of various acid-base and redox reactions in biological system. The main focus in bioinorganic chemistry is to elucidate the structural and functional roles of metals in biological systems. Among all transition metal ions, Cu2+ and Fe3+ are especially versatile and important due to their abilities to go through redox efficiently. This dissertation can be divided into four main chapters. The bioinorganic chemistry of Cu- and Fe-containing proteins were briefly discussed in Chapter one. The next chapter focuses on bacitracin, a cyclic peptide-based antibiotic produced by soil bacteria Bacillus subtilis. Bacitracin is a metalloantibiotics that can coordinate with many transition metal ions and exhibit different biological activities. In the first part of Chapter two, the aim is to explore the chemicals interactions in soil micro-ecology by investigating the interactions of different flavonoids and Cu(II)-bacitracin complex. The second part of chapter two demonstrated the binding and oxidation activity of iron(III)-bacitracin. Metal-mediated oxidative stress plays a crucial role in the development of different neurodegenerative diseases. In chapter 3, various synthetic and natural compounds were used to inhibit the oxidation chemistry mediated by Cu(II)-beta-amyloid complex associated with Alzheimer’s disease. Many proteins incorporate copper ions at their active sites for different functions, and among all of the chemistry copper-containing-proteins can perform, one of the most interesting aspect is the ability to bind and activate O2. Therefore, the biomimetic of two different Cu(II) complexes were investigated. In all studies, a combination of kinetic and different spectroscopic methods (UV-vis, NMR and resonance Raman spectroscopy) were used to study their metal binding and activity.

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33

Simoni, Déborah de Alencar. "Adsorção de Zn2+, Sr2+ e Pb2+ em fosfatos de calcio e fase ossea inorganica." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250002.

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Orientadores: Celso Aparecido Bertran, Jose de Alencar Simoni
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-05T14:47:19Z (GMT). No. of bitstreams: 1 Simoni_DeborahdeAlencar_M.pdf: 1537289 bytes, checksum: aea471071313cd94cc22964fb9d8062b (MD5) Previous issue date: 2005
Mestrado
Físico-Química
Mestre em Química

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34

Gelosi, Luca. "Studio della mobilità ambientale di contaminanti inorganici su fanghi da dragaggio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3064/.

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La gestione di fanghi da dragaggio richiede una buona conoscenza della natura degli inquinanti da cui essi sono contaminati. Questo studio si è posto l’obiettivo di individuare una strategia di caratterizzazione applicata a sedimenti dragati nel Porto di Ravenna. Particolare attenzione è stata rivolta allo studio della mobilità degli inquinanti inorganici (metalli pesanti), sia sul materiale tal quale che sui residui ottenuti dopo trattamento di soil washing, operazione prevista al fine di separare sabbie a basso carico di contaminanti dalla frazione sitosa-argillosa dove si ha la maggior concentrazione di contaminanti. Lo studio sulla mobilità è stato eseguito avvalendosi di opportuni test di rilascio, valutando gli effetti di diversi parametri, quali pH, tempo di dilavamento, rapporto solido-liquido. In conclusione, dai risultati della caratterizzazione chimica si è potuto valutare l’efficienza del Soil Washing sui sedimenti trattati: efficienza elevata per le componenti organiche, meno vistosa la decontaminazione dei metalli sulle sabbie per valori bassi di contaminazione. I sedimenti e le sabbie non presentano livelli di contaminazione preoccupanti, cosa che li renderebbe idonei al riuso secondo le modalità previste. Il metallo la cui lisciviazione dipende maggiormente dal pH è lo Zn, il Cu è il metallo più influenzato dalla complessazione con la sostanza organica, l’As è l’unico metallo ad avere massima lisciviazione a pH basico. Dopo trattamento Soil Washing tutti i metalli ad esclusione di Cu e del Fe aumentano la loro mobilità nella frazione fina rispetto al sedimento tal quale.

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35

Kaswalder, Francesco <1980&gt. "Cluster metallo carbonilici funzionali ad elettronica molecolare." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1041/1/Tesi_Kaswalder_Francesco.pdf.

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36

Kaswalder, Francesco <1980&gt. "Cluster metallo carbonilici funzionali ad elettronica molecolare." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1041/.

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37

DEMIRCI, CANSUNUR. "Metallic Nanoparticles and their Application in Heterogeneous Catalysis for Environmental Sciences." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1019238.

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This thesis provides a comprehensive concept on how catalysis can tackle climate change and global warming by reducing greenhouse gases using three different approaches. In a first approach, gold nanoparticles were synthesized by means of a colloidal synthesis method and subsequently transformed to 3D gold structures, which allowed for the selective oxidative coupling of methanol to methyl formate and by this, reducing the emission of carbon dioxide (CO2) as a side-product. In a second approach, the wetness incipient impregnation method was utilized to obtain a palladium catalyst supported on aluminum oxide, which was investigated for its activity in the lean methane oxidation at elevated pressures and temperatures. Elevated pressures allowed overall higher combustion rates of methane to CO2, which is, in perspective, less harmful as a greenhouse gas than methane. The last approach tackled the reduction of CO2, using this greenhouse gas as a feedstock to reduce it electrochemically over nanoparticulate copper and gold catalyst, which were synthesized using the chemical solution deposition method followed by an in-situ electrochemical reduction. The final products of this reaction can be hydrocarbons, which can be utilized as fuels or chemicals. All in all, the idea was to find catalysts and methods to contribute to the reduction of potential greenhouse gases and finally closing the carbon cycle for a more sustainable and greener future of planet Earth.

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38

STAGI, LUIGI. "Optical and structural characterization of metal oxides and carbon nitride compounds for the development of organic/inorganic hybrid systems." Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266677.

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Metal oxides (MOs) play a key role in many areas of chemistry, physics and materials science. They are characterized by a wide variety of high technological interest compounds (e.g. TiO2, Fe3O4, Fe2O3, Y2O3, ZnO). The still increasing interest for this class of materials is mainly due to the ability to take advantage of their diversity to find new important applications in several research field. Their applicability, strengthened by the low cost, safety, ease of synthesis, ranges from (photo)catalysis to microelectronics and in vivo biological studies. Most of the MOs-based devices present outstanding performance derived from their reduced dimensions. To date, the research on nanostructured MOs is highly active in order to deeper gain knowledge about surface states and their influence on chemical and physical properties, motivating an always more multidisciplinary approach. However, some characteristics of oxides can limit their use, e.g. high band gap with almost negligible absorption in the visible, lack of optical response (luminescence) or conduction band edge not sufficiently negative to promote proton reduction (limited photocatalytic activity). The introduction of doping elements in the MO matrix to reduce these limitations can have the drawbacks of the new defects generation at the surface and/or in the bulk. Other limitations can be overcome by creating hybrid materials, such as organic and inorganic systems. In such scenario, it is necessary a detailed study aimed to characterize the properties of organic material and the means of implementation of the hybrid system. In the first part of the present thesis, we examine the stability of some exemplar metal oxides systems. The aim of this work is to extend the comprehension of nanostructured MOs phase transformation and to analyse the conditions for which the transformation takes place. The second part presents a study on carbon nitride (CN) based molecular materials performed with spectroscopy and X-ray diffraction experiments. Our characterizations reveal that CN materials present high chemical and physical stability and good control of the optical properties. Finally, we propose a structural and optical characterization of some carbon-nitride/ metal oxides hybrids. Firstly, we focus on Tb3+ doped Y2O3 system, a good candidate for nanosized phosphors, where organic passivation of the surfaces by melamine (C3H6N6) has the dual role of replacing species for hydroxides quenchers and activators of Tb by energy transfer mechanism. Then, we conclude with TiO2/CN hybrids for photocatalysis applications, realized by chemical methods and atomic layer deposition, stressing the importance of functional and terminating groups of molecular systems.

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39

Quattrini, Federico. "Emerging Techniques for Inorganic Metal Speciation and Bioavailability." Doctoral thesis, Universitat de Lleida, 2018. http://hdl.handle.net/10803/664422.

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El coneixement profund de la especiació dels metalls pesants és clau per a determinar la seva biodisponibilitat. Per això cal complementar la informació sobre les concentracions amb la informació sobre els fluxos d’internalització. Diverses tècniques analítiques han estat desenvolupades amb aquesta fi, i algunes d’elles aprofiten les propietats de les resines d’intercanvi iònic o quelants. D’una banda, aquesta tesi investiga la velocitat d’acumulació d’ions metàl·lics a la resina Chelex 100, sigui experimentalment o a través d’un model teòric. Aquesta interpretació permet descriure els efectes dels lligands competidors i determinar les constants de dissociació dels complexes. D’altra banda, dues noves tècniques analítiques han estat desenvolupades. La primera deriva de la IET, una tècnica comunament utilitzada en equilibri, però n’extreu informació dinàmica. La segona és una modificació del popular DGT, que s’ha emprat un cop el sistema ha assolit l’equilibri.
El conocimiento profundo de la especiación de los metales pesados es clave para determinar su biodisponibilidad. Por eso es necesario complementar la información sobre las concentraciones con la información sobre los flujos de internalización. Diversas técnicas analíticas han sido desarrolladas con este fin, y varias aprovechan propiedades de las resinas de intercambio iónico o quelantes. Por un lado esta tesis investiga la velocidad de acumulación de iones metálicos en la resina Chelex 100, tanto experimentalmente, como a través de un modelo teórico. Esta interpretación permite, asimismo, describir los efectos de los ligandos competidores y determinar las constantes de disociación de los complejos. Por otro lado, dos nuevas técnicas analíticas han sido desarrolladas. La primera deriva de la IET, una técnica comúnmente utilizada en equilibrio, pero extrae información dinámica de ella. La segunda es una modificación del popular DGT, que se ha empleado una vez el sistema ha alcanzado el equilibrio.
A deep knowledge of heavy metal ions speciation is key to assessing their bioavailability. In this regard, data about concentrations should be complemented with data about the internalization fluxes. Several analytical techniques have been developed to this purpose, and many of them exploit properties of ion-exchange or chelating resins. On the one hand, this thesis studies the rate of metal ions uptake on Chelex 100 resin, both experimentally and through a theoretical model. This interpretation also allows describing the effect of competing ligands and determining the dissociation constants of the complexes. On the other hand, two new analytical techniques are developed. The first one stems from IET, a technique commonly used at equilibrium, but aims at extracting dynamic information from it. The second one is a modification of the well-known DGT, devised to provide information once equilibrium has been attained.

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Baggio, Filippo <1996&gt. "Sintesi e caratterizzazione di complessi luminescenti di centri metallici d10 con leganti azoto- ed ossigeno-donatori." Master's Degree Thesis, Università Ca' Foscari Venezia, 2022. http://hdl.handle.net/10579/21436.

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In questo lavoro di tesi sono stati sintetizzati e caratterizzati nuovi complessi di Cu(I) e Zn(II) con leganti N- e O-donatori nella sfera di coordinazione. Partendo da CuCl sono stati ottenuti complessi eterolettici con leganti eterociclici aromatici, quali il benzoxazolo e il benzofurazano, in combinazione con leganti P-donatori come la trifenilfosfina. Alogenuri di zinco(II), acetato di zinco(II) e Zn(NCS)2 sono stati impiegati come precursori in reazione con leganti eterociclici aromatici, quali benzotiazolo, benzotiadiazolo e benzoxazolo, e [O=P]-donatori, come il trifenilfosfinossido e la N,N,N’,N’-tetrametil-P-indol-1-il diammide fosfonica. In alcuni casi è stata osservata luminescenza nella regione del visibile. Le formulazioni proposte sono state confermate mediante spettroscopia NMR eteronucleare e IR e misure di conducibilità. Le proprietà fotofisiche dei complessi di zinco(II) sono state investigate tramite spettroscopia di assorbimento UV-vis e misure di emissione (PL), eccitazione (PLE) e decadimento luminescente. I dati ottenuti sono stati razionalizzati tramite calcoli di tipo DFT, in alcuni casi supportati anche da misure elettrochimiche.

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NIORETTINI, Alessandro. "Electroreduction of carbon dioxide over nanostructured metallic cathodes: a route towards artificial photosynthesis." Doctoral thesis, Università degli studi di Ferrara, 2023. https://hdl.handle.net/11392/2504901.

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Come è ormai ben noto i livelli di anidride carbonica nell’atmosfera stanno costantemente aumentando a causa delle attività umane contribuendo ogni giorno di più all’incremento dell’effetto serra la cui lotta rappresenta attualmente una delle più grandi sfide per la società contemporanea. In questo contesto la conversione elettrocatalitica dellaCO2 rappresenta un’interessante approccio a questo problema dal momento che permette di pensare a quello che fino ad oggi non può essere considerato altrimenti se non un prodotto di scarto, come ad una nuova ed interessante risorsa virtualmente ad impattoambientale nullo. Attraverso i processi riduttivi proposti in questo lavoro è infatti possibile accedere a molecole di grande importanza industriale ed energetica e dall’elevato valore aggiunto come ad esempio acido formico, metano e Syngas (una miscela di CO ed H2 alla base dei processi industriali di tipo Fisher-Tropsch utilizzati per la sintesi di idrocarburi). Tra i molti metalli che manifestano attività catalitica in questi processi il rame occupa sicuramente un ruolo centrale. Il lavoro principale esposto in questa tesi è infatti incentrato nello sviluppo di tecniche nuove ed innovative per incrementare la selettività di questo metallo attraverso procedure di nanostrutturazione e funzionalizzazione con diverse specie metalliche. Una delle vie maggiormente percorsa consiste nella formazione controllata di ossidi di rame sottoposti poi ad una successiva riduzione nello stesso ambiente di CO2R. Numerose strategie sono state riportate in letteratura a questo proposito. Sulla base di questi lavori è descritto un metodo puramente elettrochimico ed innovativo per la sintesi di interfacce rame-indio dalle ottime proprietà catalitiche. Questo tipo di catodi è stato studiato nel dettaglio e caratterizzato morfologicamente ed elettrochimicamente permettendo di poter osservare efficienze riduttive in grado di eccedere il 70% in solo monossido di carbonio con una conseguente selettività verso il Syngas attorno al 100% dipendentemente dal potenziale applicato e dalla quantità di indio fissata sulla superficie. La letteratura in merito ad elettrodi Cu-In è tuttora molto limitata, in particolare i catodi Cu-In descritti in questa tesi sono in grado di produrre selettivamente miscele di Syngas ideali per la sintesi di metanolo ed aldeidi (oltre che di idrocarburi a più elevato peso molecolare) a potenziali particolarmente accessibili contenuti in una finestra che va da -1.3V a -1.6V vs SCE con delle correnti associate compatibili per applicazioni su più ampia scala. Durante questo lavoro di ricerca sono stati sperimentati anche diversi altri metalli per la funzionalizzazione delle interfacce di rame, in particolare risultati interessanti sono stati ottenuti anche con la deposizione di Cerio, che ha modificato la selettività verso la produzione del metano con efficienze massime osservate attorno al 40%. Inoltre grazie ad una collaborazione con l’università di Milano è stato possibile studiare le caratteristiche di particolari catodi in oro depositati su FTO tramite PLD che si sono dimostrati particolarmente selettivi nei confronti del CO e dell’acido formico. La deposizione PLD ha infatti permesso di accedere a nuove e peculiari nano strutture non ottenibili tramite le tecniche tradizionali di deposizione. Sono infatti descritte interfacce decorate da nanostrutture di forma colonnare e porosa, quest’ultima particolarmente selettiva per miscele di Syngas 40% CO e 60% H2 (ideale per la sintesi di idrocarburi a vario range di pesi molecolari) prodotte a potenziali relativamente blandi attorno a -1.1V vs SCE. Il lavoro contenuto in questa tesi di dottorato è stato oggetto di pubblicazioni su riviste di settore ed ha portato al deposito di un brevetto italiano ed europeo grazie alla collaborazione con realtà industriali interessate all’applicazione di questo tipo di tecnologie.
The level of carbon dioxide in the atmosphere is constantly growing mainly due to anthropogenic activities causing the well known greenhouse effect that represent one of the greatest challenges to contemporary society. On this regard electroreduction of CO2 represents an appealing strategy to rethink a waste and an environmentally dangerous product as an innovative feedstock for the formation of value-added carbon neutral compounds. Among metal electrodes able to catalyze such process, copper plays a central role. The work of this thesis focuses into the development of new and innovative strategies aimed at tuning Cu selectivity comprise nanostructuring and alloying with heterometals. One of the more investigated nanostructuring strategies consist in the controlled formation of Cu oxides, which then undergo to a re-reduction in CO2R conditions. Several strategies have been reported for the oxidation of Cu foils’ surface. In this contribution, are reported straightforward electrochemical methods for the formation of Cu-In interfaces. The latter were fully characterized and then used as cathodes for CO2 electroreduction, leading to the selective production of Syngas with efficiencies that exceed 70% only for carbon monoxide, whose composition varies upon changing the applied bias and Indium content. Literature examples of copper-indium nanostructured catalysts for CO2R are now still limited.[5] In particular, the proposed Cu-In cathode in this work is able to efficiently catalyze gaseous mixtures compatible with the Fischer-Tropsch synthesis of methanol or aldehydes, that are produced at a relative low (i.e. -1.3 V vs SCE up to -1.6 V vs SCE) applied bias with the development of interesting stable current densities. During this research work was investigated the co-functionalization of also other metallic species than indium such as Cerium that was able to drive the selectivity of the copper interface towards an enhanced production of methane (up to 40% in faradic efficiency). Furthermore, thanks to a collaboration with the Milan University a detailed study of gold nanostructures deposited via PLD on FTO substrates was also performed leading to the development of a particularly efficient electrocatalyst for the production of Syngas and formic acid. In particular with the pulsed laser deposition it was possible to generate particular nanostructures that are not achievable by standard synthetic methodologies, two of these were found to be interesting in terms of catalytic performance. In fact the study was centered into the description of a columnar cathodic interface and a “foam” like surface, the latter was the most interesting due to it’s selectivity towards a Syngas mixture of 40% CO and 60% H2 at a low applied bias of -1.1V vs SCE, ideal for the synthesis of hydrocarbons with a wide range of molecular weight. The work described in this thesis leads to the publications in multiple scientific journal and the deposition of an Italian and European patent due to the collaboration of interested industries in the application of this know how, on this regard also a lot of specific studies were carried out with the aim of clarify the technoeconomic potential of this technology and the possibility to scale up from the laboratory scale to a plant simulation not only in theory but also with the design and development of larger electrochemical cells and setup.

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42

Hofer, Angelika <1984&gt. "Studio della componente organica ed inorganica del particolato atmosferico." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/4659.

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Il monitoraggio della qualità dell’aria é un primo passo attraverso un futuro migliore perché ci segnala quale processo emette più sostanze dannose nell’atmosfera e dove c’è bisogno di applicare tecnologie nuove per ridurre le emissioni. In questo lavoro, la componente organica (IPA, TC-EC-OC, levoglucosano) e quella inorganica (metalli) sono state determinate mediante il monitoraggio attivo (filtri) e il biomonitoraggio (T. aeranthos).
In this study, the organic and inorganic fraction of the airborne particulate matter was determined on a) filter devices (active sampling), and b) by biomonitoring (passive sampling). Organic components of the atmospheric particulate such as PAH, compounds out of the carbonaceous fraction, and levoglucosan, which are demonstrated to induce adverse effects on humans’ health, were detected. Further, also inorganic compounds such as As and Hg were found in some exposed samples. Monitoring the components of the air is a first step towards an increase in life quality.

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43

Mercy, Michel. "Contribution à l'étude des relations entre coefficients d'accommodation et physisorption." Nancy 1, 1989. http://www.theses.fr/1989NAN10221.

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Le présent travail vise à déterminer dans quelle mesure la physisorption d'un gaz A sur une surface peut modifier le coefficient d'accomodation thermique d'un gaz B sur cette même surface. Le système considéré est celui de l'hélium s'accomodant sur une surface de tungstène nue ou recouverte de xénon ou de krypton physisorbé

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44

Luciano, Eramanno. "Sviluppo di nuovi sistemi catalitici dei metalli del gruppo 4 per la polimerizzazione di monomeri olefinici e polari." Doctoral thesis, Universita degli studi di Salerno, 2016. http://hdl.handle.net/10556/2176.

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2013 - 2014
In this PhD work, a series of eight new group 4 metal complexes 1−8 (1 = (t- BuOS)2TiCl2; 2 = (CumOS)2TiCl2; 3 = (t-BuOS)2Zr(CH2Ph)2; 4 = (CumOS)2Zr(CH2Ph)2); 5 = (t-BuOS)2Ti(OiPr)2; 6 = (t-BuOS)2Zr(OtBu)2; 7 = (t- BuOS)2Hf(OtBu)2; 8 = (CumOS)2Zr(OtBu)2) supported by two phenolate bidentate ligands (t-BuOS−H = 4,6-di-tertbutyl- 2-phenylsulfanylphenol and CumOS−H = 4,6-dicumyl-2- phenylsulfanylphenol) were synthesized by the reaction of appropriate metal precursors with 2 equiv of the ligands. These complexes were characterized by means of 1H- and 13C-NMR spectroscopy and the complex 6 by X-ray diffraction... [edited by author]
XIII n.s.

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45

Botter, Margherita <1977&gt. "Studio della distribuzione di microinquinanti inorganici nei sedimenti della laguna di Venezia e bioaccumulo in Zosterisessor ophiocephalus." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3957.

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The sediment quality of Venice lagoon was assessed through collection and analysis of sediment samples in 380 sites in the shallow water areas. Heavy metal (Al, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, ZN) and As contents were measured in fillet, liver, stomachs and otoliths of 280 specimens collected in five areas of the Lagoon (Laguna Nord, Ponte della Libertà, Lago dei Teneri, Poveglia and Santa Maria del Mare). The concentration of metals in most specimens does not reflect the total concentration in sediment. Cd, Hg and Pb values measured in the edible part of the fish are lower than the levels required by the European regulations, except in specimens caught in Poveglia and Santa Maria del Mare areas (for Cd and Hg). In order to evaluate the accumulation of metals in fishes from sediment the biota-sediment accumulation factor (BAF). The values of this factor were higher than 1 only relative to As, Hg and Zn. In the case of Hg, accumulation in Z. ophiocephalus was significant and was related to the phenomena of bio-geo-speciation that directly affect this metal and to its well known ability of biomagnificate along the food chain. The levels of mercury and arsenic relatively higher in fish from the areas of Poveglia and Santa Maria del Mare have been directly linked to greater bioavailability in these areas. The stomach contents, in fact, seems to explain the differences between areas, in both of the two sampling periods, for As and Hg. In the case of arsenic, it could be concluded that, for the areas of Poveglia and Santa Maria del Mare, the location was found determinant in promoting the bio-accumulation of this element in Go, beung these areas closer to the sea than the other sites.
La qualità dei sedimenti della laguna di Venezia è stata valutata attraverso la raccolta e l'analisi di campioni di sedimento in 380 siti in aree di acque basse. Le concentrazioni di metalli pesanti (Al, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, ZN) e As in filetto, fegato, contenuto stomacale e otoliti sono state misurate in 280 campioni raccolti in cinque aree della laguna (Laguna Nord, Ponte della Libertà, Lago dei Teneri, Poveglia e Santa Maria del Mare). La concentrazione di metalli nella maggior parte degli esemplari non riflette la concentrazione totale nel sedimento. I valori di Cd, Hg e Pb misurati nella parte edibile dei pesci sono bassi rispetto ai livelli stabiliti dai regolamenti europei, tranne nei Go catturati a Poveglia e Santa Maria del Mare (per Cd e Hg). La capacità dei pesci catturati di accumulare metalli dai sedimenti superficiali è stata valutata utilizzando il fattore di accumulo biota-sedimento (BAF). As, Hg e Zn sono gli unici metalli per cui si osservano valori di BAF superiori a 1. Nel caso di Hg l'accumulo nei Go risulta significativo ed è imputabile ai fenomeni di bio-geo-speciazione che interessano direttamente questo metallo e alla nota capacità di biomagnificare lungo la catena alimentare. I livelli di mercurio e arsenico relativamente più elevati nei pesci provenienti dalle aree di Poveglia e Santa Maria del Mare sono stati direttamente collegati ad una maggior biodisponibilità in queste zone. Il contenuto stomacale, infatti, sembra spiegare le differenze tra aree, in entrambi i due periodi di campionamento, per As e Hg. Nel caso dell'arsenico, si è potuto concludere che è risultato determinante nel favorire il bioaccumulo di questo elemento nei Go, per le aree di Poveglia e Santa Maria del Mare, la posizione, essendo maggiormente soggette all'apporto di acque marine rispetto agli altri siti.

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46

Elbatal, Hany. "Terpyridine-Based Metallo-Supramolecular Architectures: From Structure to Function." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384367887.

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47

SCOTTI, NICOLA. "ON THE RELATIONSHIPS BETWEEN CATALYTIC ACTIVITY AND MORPHOLOGY OF THE METALLIC PHASE IN CATALYSTS PREPARED BY CHEMISORPTION-HYDROLYSIS." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/168363.

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Chemisorption–hydrolysis (CH) represents a fruitful preparation method, as it combines the simplicity of impregnation techniques, both in terms of handiness and cheapness, with the high metal dispersion obtained by anchoring techniques. In this work different Cu, Co and Co-Cu catalysts were prepared by CH. The characterization of CH copper silica materials agree on the formation of finely dispersed phase of CuO, easily reducible to metal copper at any copper loading. In particular CH method allows to keep a great dispersion obtaining very small copper particles also to an higher metal loading (up to 15%). Moreover CH offers the possibility to tune the nature of the copper phase using different supports during catalyst preparation. In fact, if on SiO2 small and well-dispersed and easily reducible CuO particles are formed either at low and high metal loading, whereas on SiO2-Al2O3 the nature of Cu species depends on the copper amount: up to about 5 wt% only hardly reducible Cuδ+ (+1 ≤ δ ≤ +2) is formed on the catalyst, while after this loading a CuO phase easy reducible to well formed Cu (0) begins to form on the surface. Copper CH catalysts were tested in the direct epoxidation of propene with O2. Catalysts exposing only metallic copper (thus silica based ones) were those that revealed the best activity: Cu (0) appears to be the active site for the reaction. Copper catalyst are well known to catalyze hydrogenation reaction, moreover Zaccheria et al. reported a bifunctional process of etherification starting from 4-methoxyacetophenone in presence of 2-propanol. Two steps are involved in the process: the hydrogenation of ketone to the alcohol and the subsequent acid reaction with 2-propanol and 1-(4-methoxyphenyl)ethanol to give the corresponding ether. The structure sensitivity of these two separate reactions was studied on 8.5 and 15 wt% reduced Cu/SiO2 Chrom CH catalysts. The results indicates that both the reactions depend on terrace atoms. Also well dispersed Co/SiO2 and CO-Cu/SiO2 catalysts were successfully prepared with a modified CH method. A Co (II) hardy reducible phase was generated on Co/SiO2, while on the bimetallic materials more easily reducible Co species were formed. Catalytic experiments on methanol decomposition indicate that Co-Cu/SiO2 catalysts show higher CH3OH conversion and higher CO selectivity compared to single Co and Cu catalysts with the same total amount of metal. The control of morphology (size, shape and surface structures) is a very important method in order to tune catalytic, electronic and optical proprieties of metal nanoparticles. An ideal heterogeneous catalyst should be composed by exactly the same nanometric size metal nanoparticles, uniformly dispersed in the support. Bovine serum albumin (BSA) was used as surfactant for the shape controlled synthesis of Au nanoparticles by a modified polyol processs. We successfully prepared Au nanocrystals of different shape: octahedra, cubes and tetrahxaedra. In particular the innovative use of BSA allows one to synthesize tetrahexahedra, an unusual shape for metal nanocrystals. The shape controlled synthesis of metal nanocrystals bounded by high-index facets (such as tetrahexahedra) is a potential route to obtain materials with enhanced catalytic performances, since high-index crystal planes generally show much higher activity than that of the most common stable low-index planes, due to high surface energy and roughness.

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48

Bergstrom, Alexander R. "SPECTROSCOPIC AND MECHANISTIC STUDIES OF METALLO-BETA-LACTAMASE INHIBITORS AND THE STRUCTURE-FUNCTION RELATIONSHIP OF NEW DELHI METALLO-BETA-LACTAMASE VARIANTS." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1524154064246174.

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49

Behra, Philippe. "Etude du comportement d'un micropolluant metallique (le mercure) au cours de sa migration a travers un milieu poreux sature : identification experimentale des mecanismes d'echanges et modelisation des phenomenes." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13120.

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50

Pontes, Daniel de Lima. "Estudo de complexos de ferro-cyclam com ligantes carboxilados e polinitrilados." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=2934.

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CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior
O objetivo deste trabalho Ã contribuir com o desenvolvimento da quÃmica do sistema Fe-cyclam, atravÃs da sÃntese e caracterizaÃÃo de novos complexos metÃlicos deste sistema com duas classes de ligantes: carboxilados (oxalato e acetato) e ligantes polinitrilados (7,7,8,8 âtetracianoquinodimetano e tetracianoetileno ). AtravÃs da caracterizaÃÃo do complexo cis-[Fe(cyclam)ox]PF6 por infravermelho foi possÃvel identificar que o ligante oxalato encontra-se coordenado ao centro metÃlico de forma bidentada, bem como garantir que o ligante macrocÃclico cyclam continua na esfera de coordenaÃÃo do metal. O potencial formal de meia onda do processo redox Fe3+/2+ do complexo foi observado em â39mV vs Ag/AgCl. O potencial observado encontra-se deslocado 240mV para menores valores em relaÃÃo ao complexo precursor, favorecendo ao estado de oxidaÃÃo Fe3+ do metal, devido ao maior efeito σ doador do ligante oxalato frente aos cloretos. O espectro UV-Vis do complexo cisâ[Fe(cyclam)ox]PF6, em meio aquoso, apresentou trÃs bandas: 229nm, atribuÃda a uma transiÃÃo intraligante do cyclam, 293nm e 357nm, atribuÃdas Ã transferÃncia de carga de orbitais π do ligante para o orbitais dπ* do metal. Os experimentos fotoquÃmicos demonstraram a grande sensibilidade do complexo Ã luz, sendo observado a labilizaÃÃo do ligante oxalato da esfera de coordenaÃÃo do metal, e a reatividade da espÃcie formada atravÃs da obtenÃÃo do complexo trans-[Fe(cyclam)acet2]PF6, AtravÃs do estudo de Raio-X, obtido a partir do cristal do complexo trans-[Fe(cyclam)acet2]PF6, foi possÃvel comprovar o modo de coordenaÃÃo das duas molÃculas de acetato na posiÃÃo trans, bem como a identificaÃÃo da disposiÃÃo do cyclam no plano da molÃcula atravÃs de um arranjo conformacional trans-III. Os espectros no infravermelho dos complexos cis - [Fe(cyclam)(TCNX)Cl]Cl, onde TCNX representa os ligantes TCNQ ou TCNE, apresentaram um maior nÃmero de bandas referentes aos estiramentos CN, comparativamente aos ligantes livres, confirmando a alteraÃÃo da simetria do ligante causada pela coordenaÃÃo do metal. Com base nos deslocamentos destas freqÃÃncias para menores valores, comparativamente ao ligante livre, foi possÃvel identificar que os ligantes TCNQ e TCNE estÃo coordenados em sua forma radicalar, estado de oxidaÃÃo â1, sugerindo assim a ocorrÃncia de um processo de transferÃncia de elÃtrons do centro metÃlico, previamente reduzido (Fe2+), para os ligantes TCNX. Os potenciais redox dos Ãtomos de ferro, nos complexos com os ligantes polinitrialados TCNQ (693mV vs ENH) e TCNE (854mV vs ENH), foram deslocados para potenciais mais positivos, comparativamente ao observado no complexo precursor cis-[Fe(cyclam)Cl2]Cl (405mV vs ENH), indicando assim um forte deslocamento de densidade eletrÃnica dπ para os orbitais de simetria π dos ligantes TCNX. Os processos centrados nos ligantes coordenados ficaram mais prÃximos do que nos ligantes livres, indicando uma diminuiÃÃo na barreira de transferÃncia de elÃtrons, que segundos dados da literatura leva a uma melhor conduÃÃo elÃtrica. Os espectros eletrÃnicos dos complexos, em meio aquoso, apresentaram uma banda localizada em baixa energia, atribuÃda a transferÃncias de carga do tipo LMCT dos orbitais pπ das molÃculas de TCNX, para os orbitais dπ* do Ãon Fe3+. No complexo com o ligante TCNQ, esta banda aparece em 764nm e no complexo com o ligante TCNE, em 861nm. Observa-se ainda nos dois complexos a presenÃa das bandas referentes Ãs transiÃÃes LMCT dos cloretos para o Ãon Fe3+ em regiÃes muito prÃximas, em 557 no complexo com TCNE e em 568nm no complexo com TCNQ. A presenÃa desta banda novamente sugere a presenÃa do Ferro no estado oxidado (Fe+3).
The main objective of this work is to contribute with the chemistry of the system Fe-Cyclam through the synthesis and characterization of complexes with carboxylate ligants, acetate and oxalate, and polinitrilate ligands, 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetracyanoethylene (TCNE). The infrared spectra of the cis-[Fe(cyclam)ox]PF6 complex allowed to identify the coordination of the oxalate ligand to the iron metal in a bidentate mode as well as to suggest the presence of the macrocycle in the coordination sphere of the metal. The redox potential of the complex was observed at â39mV vs Ag/AgCl. The potential is dislocated 240mV for more positive potential when compared to that observed for the precursor complex cis-[Fe(cyclamCl2]Cl. This effect can be attributed to the stronger σ effect of the oxalate ligand when compared to the chlorine. The UV-Vis spectra of the complex, presented three bands: 229nm, attributed to a cyclam intraligand transition and the bands 293nm and 357nm, referring to ligand to metal electronic transfer from π orbitals of the oxalate to dπ* of the metal. The photochemical experiments proved the great sensibility of the complex to the light presence, being observed the reactivity effect of the complex formed after the light exposition by the formation of the trans-[Fe(cyclam)acet2]PF6 complex. Through the Ray-X obtained of the crystal of the trans-[Fe(cyclam)acet2]PF6 complex was possible to identify the coordination of two molecules of acetate at the trans position, as well as to identify the disposition of the cyclam ligand on the plane in a trans-III arrange. The infrared spectrum of the complexes cis - [Fe(cyclam)(TCNX)Cl]Cl, where the TCNX represent the ligands TCNQ and TCNE, present a great number of bands referring to the νCN, when compared with the ligands not coordinated, confirming the symetry changed induced by the metal coordination. Through the wavenumber variation of these bands was possible to identify that the TCNQ and TCNE ligands are coordinated in your radical way, oxidation state â1, suggestion this way the occurrence of a electron transfer from the iron, previously reduced (Fe+2), to the TCNX ligands. The redox potentials of the iron metals in the complexes with the polinitrilate ligands TCNQ (693mV vs ENH) and TCNE (854mV vs ENH) were dislocated for more positive potentials, when compared to the cis-[Fe(cyclam)Cl2]Cl precursor complex (405mV vs ENH), indicating the occurrence of an electronic density transfer to the TCNX molecules. The two potentials of the ligands on the complexes were closer than the ligands not coordinated, this approximation of the potential indicate a decrease of the inner electron transfer. The electronic spectra of the complexes, showed bands in the low energy region, attributed to a charge transfer LMCT, from the TCNX pπ orbital to the metal dπ* orbital. In the cis-[Fe(cyclam)(TCNQ)Cl]Cl complex, the band was observed at 764nm while in the complex with the TCNE ligand this band was observed at 861nm. Also, the complexes presented bands at 557nm (TCNE complex) and 568nm (TCNQ complex)referring to the LMCT transitions from the chlorine atoms to the iron metal reinforcing the assignment of the (Fe+3) oxidation state for the metal center.

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Дисертації з теми "METALLIC AND INORGANIC"

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