Dissertations / Theses on the topic 'Sulfide nanoparticles'
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1
Junkermeier, Chad Everett. "Simulation and Analysis of Cadmium Sulfide Nanoparticles." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2704.pdf.
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Rijal, Upendra. "Suppressed Carrier Scattering in Cadmium Sulfide-Encapsulated Lead Sulfide Nanocrystal Films." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1402409476.
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Frenzel, Johannes. "Structural, electronic and optical properties of cadmium sulfide nanoparticles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1170678349152-44850.
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In this work, the structural, electronic, and optical properties of CdS nanoparticles with sizes up to 4nm have been calculated using density-functional theory (DFT). Inaccuracies in the description of the unoccupied states of the applied density-functional based tight-binding method (DFTB) are overcome by a new SCF-DFTB method. Density-functional-based calculations employing linear-response theory have been performed on cadmium sulfide nanoparticles considering different stoichiometries, underlying crystal structures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations (unsaturated, partly saturated, completely saturated). For saturated particles, the calculated onset excitations are strong excitonic. The quantum-confinement effect in the lowest excitation is visible as the excitation energy decreases towards the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introduce trapped surface states which lie below the lowest excitations of the completely saturated particles. The molecular orbitals (MOs), that are participating in the excitonic excitations, show the shape of the angular momenta of a hydrogen atom (s, p). Zincblende- and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles are rather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise to less pronounced spectra with lower oscillator strengths. Finally, a very good agreement of the calculated data to experimentally available spectra and excitation energies is found.
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Mbese, Johannes Zanoxolo. "Synthesis and characterization of metal sulfide nanoparticles/polymer nanocomposites." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1016190.
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The focus of this project was to synthesize and characterize metal sulfide nanoparticles /polymer nanocomposites. The work involved the synthesis of dithiocarbamato ligands and complexes derived from aniline. Zn(II), Cd(II) and Hg(II) dithiocarbamato complexes were used as single-molecule precursors for the synthesis of the ZnS, CdS and HgS nanoparticles and their optical and structural properties studied. The other focus of this work was to synthesize a combined functionality metal sulfide nanoparticles/polymer nanocomposites by dispersing as-synthesized ZnS, CdS and HgS nanoparticles in polymethyl methacrylate (PMMA) matrix. The characterization of the ligands, complexes, nanoparticles and nanocomposites were investigated using relevant instrumental tools like UV-Vis, photoluminescence (PL), Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersion X-ray (EDX), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
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Frenzel, Johannes. "Structural, electronic and optical properties of cadmium sulfide nanoparticles." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A23935.
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In this work, the structural, electronic, and optical properties of CdS nanoparticles with sizes up to 4nm have been calculated using density-functional theory (DFT). Inaccuracies in the description of the unoccupied states of the applied density-functional based tight-binding method (DFTB) are overcome by a new SCF-DFTB method. Density-functional-based calculations employing linear-response theory have been performed on cadmium sulfide nanoparticles considering different stoichiometries, underlying crystal structures (zincblende, wurtzite, rocksalt), particle shapes (spherical, cuboctahedral, tetrahedral), and saturations (unsaturated, partly saturated, completely saturated). For saturated particles, the calculated onset excitations are strong excitonic. The quantum-confinement effect in the lowest excitation is visible as the excitation energy decreases towards the bulk band gap with increasing particle size. Dangling bonds at unsaturated surface atoms introduce trapped surface states which lie below the lowest excitations of the completely saturated particles. The molecular orbitals (MOs), that are participating in the excitonic excitations, show the shape of the angular momenta of a hydrogen atom (s, p). Zincblende- and wurtzite-derived particles show very similar spectra, whereas the spectra of rocksalt-derived particles are rather featureless. Particle shapes that confine the orbital wavefunctions strongly (tetrahedron) give rise to less pronounced spectra with lower oscillator strengths. Finally, a very good agreement of the calculated data to experimentally available spectra and excitation energies is found.
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Perera, Jayalath Pathirannehelage Dimuthu Nuwan. "Photocatalytic Properties of Zinc Selenide/Cadmium Sulfide Core-shell Nanoparticles." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1370994697.
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Monahan, Bradley Michael. "Synthesis and Characterization of Phase-pure Copper Zinc Tin Sulfide (Cu2ZnSnS4) Nanoparticles." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404732007.
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Allehyani, S. H. A., R. Seoudi, D. A. Said, A. R. Lashin, and A. Abouelsayed. "Synthesis, Characterization, and Size Control of Zinc Sulfide Nanoparticles Capped by Polyethylene Glycol." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42490.
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Zinc sulfide nanoparticles were synthesized with controllable size via chemical precipitation. highresolution transmission electron microscopy (HRTEM) and X-ray powder diffraction (XRD) showed that the samples were grown with the cubic phase; the particle size was varied by varying the molar ratios of zinc chloride and sodium sulfide in the presence of poly(ethylene glycol). The optical band gap was calculated on the basis of ultraviolet-visible spectroscopy (UV-VIS) and ranged from 4.13 eV to 4.31 eV depending on the particle size. Surface passivation and adsorption of poly(ethylene glycol) on the nanoparticles was explained on the basis of Fourier transform infrared measurements (FTIR).
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Mousavi, R. A., A. A. Sepahy, and M. R. Fazeli. "Biosynthesis, Purification and Characterization of Cadmium Sulfide Nanoparticles Using Enterobacteriaceae and their Application." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34903.
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The area of nanotechnology encompasses the synthesis of nanoscale materials, the understanding and
the utilization of their physicochemical and optoelectronic properties, and the organization of nanoscale
structures into predefined superstructures. The development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. Nanotechnology has recently emerged as an elementary division of science and technology that investigates and regulates the interaction at cell level between synthetic and biological materials with the help of nanoparticles.
A wide range clean, nontoxic and eco-friendly synthesis of nanoparticles is an important aspect of current
nanotechnology. Microbial synthesis of nanoparticles is a Green chemistry approach that interconnects
nanotechnology and microbial biotechnology. Microorganisms play an important role in the eco-friendly
synthesis of metal nanoparticles. This study illustrates the synthesis of CdS nanoparticles using the bactetia of Enterobacteriaceae ( Escherichia coli PTCC 1533 and Klebsiella pneumonia PTCC 1053) after 96 h of
incubation at room temperature (30ºc) and pH 9. The morphology of the samples was analyzed using Scanning electron microscopy(SEM). The size of CdS nanoparticles in aqueous solution has been calculated using UV–Vis spectroscopy, XRD, FTIR, EDS and SEM measurements. The nanoparticles are found to be
polydisperse in the size range 5–200 nm.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34903
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Xiong, Zhong Zhao Dongye. "Destruction of perchlorate and nitrate by stabilized zero-valent iron nanoparticles and immobilization of mercury by a new class of iron sulfide nanoparticles." Auburn, Ala, 2007. http://repo.lib.auburn.edu/2007%20Fall%20Dissertations/Xiong_Zhong_0.pdf.
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Yang, Zhiqiang. "Preparation of palladium, palladium sulfide, cadmium selenide nanoparticles and magnesium oxychloride, magnesium hydroxide nanorods." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/891.
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Roffey, A. R. "Dithiocarbamate complexes as single source precursors to metal sulfide nanoparticles for applications in catalysis." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1437012/.
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Herein we report the solvothermal decomposition of a range of metal dithiocarbamate complexes for the synthesis of metal sulfide nanoparticles. Metal sulfides exist in a variety of structural phases, some of which are known to be catalytically active towards various processes. The aim of this work was to synthesise a variety of different metal sulfide phases for future catalysis testing, particularly the iron sulfide greigite (Fe3S4, a thiospinel containing Fe2+ and Fe3+) which is to be tested for CO2 reduction. A range of metal dithiocarbamate complexes were synthesised and Chapter 2 focusses on the synthesis of iron dithiocarbamates. Both iron(II) and iron(III) complexes were synthesised, the latter being a facile, open bench reaction producing a range of [Fe(S2CNRR’)3] complexes. Iron(II) bis(dithiocarbamates) are extremely air sensitive therefore carbonyl protected [Fe(S2CNRR’)2(CO)2] complexes were prepared for ease of use as precursors. The stability of the complexes was tested by TGA to ensure they were suitable precursors for metal sulfide synthesis, i.e. that the carbonyl ligands were sufficiently labile to leave the complexes before decomposition, which proved to be successful. In the following Chapter these iron dithiocarbamate complexes were solvothermally decomposed, but interestingly a combination of iron(II) and iron(III) precursors did not produce greigite as expected, but pyrrhotite (Fe7S8, containing only Fe2+). Systematic studies into the effect of decomposition temperature, precursor concentration and precursor type, on the phase and morphology of the resulting iron sulfide nanoparticles were performed on the iron(III) dithiocarbamate precursor. The phase was found to be highly dependent on both concentration and temperature. The use of a redox active additive, thiuram disulfide, on the decomposition was also investigated and found to have a significant effect, promoting the formation of the metastable greigite phase. Chapter 4 examines the nickel bis(dithiocarbamate) decomposition system to see if its behaviour was consistent with trends observed in the iron case. In general, similar trends were observed in the phase and morphology of the nickel sulfides when the decomposition parameters were varied, metastable phases were observed at lower temperature and higher concentration. The effect of thiuram disulfide on the system was greater, however, than in the iron case, whereby an additional nickel sulfide phase (NiS2) was observed at high concentration in the presence of this additive. Chapter 5 deals with a broader range of metal dithiocarbamate systems, to attempt to elucidate whether or not the trends seen for nickel and iron are universal for metal dithiocarbamate precursors. The Co, Cu, Zn and In dithiocarbamate systems were examined with and without thiuram disulfide, and some effect were seen on the phase of metal sulfide nanoparticle formed, but only at high concentration in the presence of the additive. Mixed-metal studies were performed to investigate the suitability of metal dithiocarbamates as precursors to ternary metal sulfides, and success was observed for iron-nickel, cobalt-nickel and iron-copper sulfides, though the iron-zinc and iron-indium systems only produced binary sulfides. The final Chapter looks into the metal dithiocarbamate decomposition mechanism in detail, using [Ni(S2CNiBu2)2] as a model system. NMR, in situ UV-vis, MS and powder XRD are all employed to probe the mechanism, in conjunction with XAS and computer modelling which was performed by others. The mechanism was found to rely heavily on an intermediate formed from amide exchange between the dithiocarbamate backbone and solvent amine, indicating the solvent plays an extremely significant role in the solvothermal synthesis of metal sulfides from dithiocarbamate precursors.
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Yukna, Jennifer. "Computational and experimental investigations of the structural properties, electronic properties, and applications of silver, gold, mercury selenide, silver sulfide, and nickel sulfide nanoparticles /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1482010021&sid=2&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Thesis (Ph. D.)--Southern Illinois University Carbondale, 2007."Department of Chemistry and Biochemistry." Keywords: Electronic properties, Silver, Gold, Mercury selenide, Silver sulfide, Nickel sulfide, Nanoparticles. Includes bibliographical references (p. 170-180). Also available online.
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Gonzalez-Estrella, Jorge Gonzalez. "Toxicity of Engineered Nanoparticles to Anaerobic Wastewater Treatment Processes." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347117.
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Nanotechnology is an increasing market. Engineered nanoparticles (NPs), materials with at least one dimension between 1 and 100 nm, are produced on a large scale. NPs are vastly used in industrial processes and consumer products and they are most likely discharged into wastewater treatment plants after being used. Activated Sludge is one of the most applied biological wastewater treatment processes for the degradation of organic matter in sewage. Activated sludge produces an excess of sludge that is commonly treated and stabilized by anaerobic digestion. Recent studies have found that NPs accumulate in the activated sludge; thus, there is a potential for the concentrations of NPs to magnify as concentrated waste sludge is fed into the anaerobic digestion process. For this reason, it is important to study the possible toxic effects of NPs on the microorganisms involved in the anaerobic digestion process and the approaches to overcome toxicity if necessary. The present work evaluates the toxic effect of NPs on anaerobic wastewater treatment processes and also presents approaches for toxicity attenuation. The first objective of this dissertation (Chapter III) was to evaluate the toxicity of high concentrations (1, 500 mg L⁻¹) of Ag⁰, Al₂O₃, CeO₂, Cu⁰, CuO, Fe⁰, Fe₂O₃, Mn₂O₃, SiO₂, TiO₂, and ZnO NPs to acetoclastic and hydrogenotrophic methanogens and the effect of a dispersant on the NPs toxicity to methanogens. The findings indicated that only Cu⁰ and ZnO NPs caused severe toxicity to hydrogenotrophic methanogens and Cu⁰, CuO, and ZnO NPs to acetoclastic methanogens. The dispersant did not impact the NPs toxicity. The concentrations of Cu⁰ and ZnO causing 50% of inhibition (IC₅₀) to hydrogenotrophic methanogens were 68 and 250 mg L⁻¹, respectively. Whereas the IC₅₀ values for acetoclastic methanogens were 62, 68, and 179 for Cu⁰, ZnO, and CuO-Cu NPs respectively. These findings indicate that acetoclastic methanogens are more sensitive to NP toxicity compared to hydrogenotrophic methanogens and that Cu⁰ and ZnO NPs are highly toxic to both. Additionally, it was observed that the toxicity of any given metal was highly correlated with its final dissolved concentration in the assay irrespective of whether it was initially added as a NP or chloride salt, indicating that corrosion and dissolution of metals from NPs may have been responsible for the toxicity. The second objective of this dissertation (Chapter IV) was to evaluate the Cu⁰ NP toxicity to anaerobic microorganisms of wastewater treatment processes. Cu⁰ is known to be toxic to methanogens; nonetheless, little is known about its toxic effects on microorganisms of upper trophic levels of anaerobic digestion or other anaerobic process used for nitrogen removal. This specific objective evaluated Cu⁰ NP toxicity to glucose fermentation, syntrophic propionic oxidation, methanogenesis, denitrification and anaerobic ammonium oxidation (anammox). Chapter IV showed that anammox and glucose fermentation were the least and most inhibited processes with inhibition constants (K(i)) values of 0.324 and 0.004 mM of added Cu⁰ NPs, respectively. The Ki values obtained from the residual soluble concentration of the parallel experiments using CuCl₂ indicated that Cu⁰ NP toxicity is most likely caused by the release of soluble ions for each one of the microorganisms tested. The results taken as a whole demonstrate that Cu⁰ NPs are toxic to a variety of anaerobic microorganisms of wastewater treatment processes. The third objective of this document (Chapter V) was to study the role of biogenic sulfide in attenuating Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Previous literature results and research presented in this dissertation indicated that the release of soluble ions from Cu and ZnO NPs cause toxicity to methanogens. In the past, the application of sulfide to precipitate heavy metals as inert non-soluble sulfides was used to attenuate the toxicity of Cu and Zn salts. Building on this principle, Chapter V evaluated the toxicity of Cu⁰ and ZnO NPs in sulfate-containing (0.4 mM) and sulfate-free conditions. The results show that Cu⁰ and ZnO were 7 and 14x less toxic in sulfate-containing than in sulfate-free assays as indicated by the differences in K(i) values. The K(i) values obtained based on the residual metal concentration of the sulfate-free and sulfate-containing assays were very similar, indicating that the toxicity is well correlated with the release of soluble ions. Overall, this study demonstrated that biogenic sulfide is an effective attenuator of Cu⁰ and ZnO NP toxicity to acetoclastic methanogens. Finally, the last objective (Chapter VI) of this dissertation was to evaluate the effect of iron sulfide (FeS) on the attenuation of Cu⁰ and ZnO toxicity to acetoclastic methanogens. FeS is formed by the reaction of iron(II) and sulfide. This reaction is common in anaerobic sediments where the reduction of iron(III) to iron(II) and sulfate to sulfide occurs. FeS plays a key role controlling the soluble concentrations of heavy metals and thus their toxic effects in aquatic sediments. This study evaluated the application of FeS as an approach to attenuate Cu⁰ and ZnO NP toxicity and their salt analogs to acetoclastic methanogens. Two particle sizes, coarse FeS (FeS-c, 500-1200 µm) and fine FeS (FeS-f, 25-75 µm) were synthesized and used in this study. The results showed 2.5x less FeS-f than FeS-c was required to recover the methanogenic activity to the same extent from the exposure to highly inhibitory concentrations of CuCl₂ and ZnCl₂ (0.2 mM). The results also showed that a molar ratio of FeS-f/Cu⁰, FeS-f/ZnO, FeS-f/Zn Cl₂, and FeS-f/CuCl₂ of 3, 3, 6, and 12 respectively, was necessary to provide a high recovery of methanogenic activity (>75%). The excess of FeS needed to overcome the toxicity indicates that not all the sulfide in FeS was readily available to attenuate the toxicity. Overall, Chapter VI demonstrated that FeS is an effective attenuator of the toxicity of Cu⁰ NP and ZnO NPs and their salt analogs to methanogens, albeit molar excesses of FeS were required.
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Sarker, Niloy Chandra. "Application of Nanoparticles in Livestock Manure for Understanding Hydrogen Sulfide and Greenhouse Gas Reduction Mechanism." Diss., North Dakota State University, 2018. https://hdl.handle.net/10365/27897.
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The agricultural sector is one of the sources of greenhouse gases (GHGs) emission, especially methane (CH4), and contributing approximately 250 million metric ton carbon dioxide (CO2) equivalent emission per year. Almost 70% of CH4 emission from this sector is enteric fermentation, while 26% is from the livestock manure management. Both rumen and animal manure are the impending sources of carbon (C), sulfur (S), and water (H2O) and microbial populations utilize these constituents to produce GHGs, and hydrogen sulfide (H2S). Nanoparticles (NPs) application in manure is a promising treatment option for mitigating GHG and H2S gases, but limited information is available on how the reduction mechanism occurs. In this study, zinc silica nanogel (ZnSNL), copper silica nanogel (CuSNL), and nano acetyl cysteine (NACL) coated zinc oxide quantum dots (Qdots), zinc oxide (nZnO), and silver (nAg) NPs were tested in manure stored under anaerobic conditions to understand the reduction mechanism of GHG and H2S resulting from NPs application. Additionally, in vitro study with nZnO and two types of feed (alfalfa and corn silage) were conducted to investigate the efficacy of nZnO in mitigating ruminal gas emission. Methane and CO2 concentrations were measured using an SRI-8610 gas chromatograph and H2S was measured using a Jerome 631X meter. Microbial populations were characterized using both plate counts and quantitative real-time polymerase chain reaction (qRT-PCR). Application of NPs reduced gas volumes ranging 16 to 99%, and concentrations reduced by 49 to ~100% for H2S, and 20.24 to ~100% for GHGs. Application of NPs reduced 38.49 to 94.32% aerobic- and 7.43% to 82.04% anaerobic-microbial populations. Furthermore, the qRT-PCR analysis showed that reduction of gases was due to the inhibition of gas specific microbial population. Overall, nZnO based treatments reduced 8.80 to 55.64% methyl coenzyme M reductase (mcrA) gene copies and 0.74 to 25.16% dissimilatory sulfide reductase (DSR). Contrariwise, compared to the control treatment, in vitro study demonstrated 4.89 to 53.65% H2S and GHGs concentration reduction with the applied nZnO inclusion rates. Additionally, alfalfa as feed exhibited 37 to 45% cumulative gas reduction than corn silage but increased GHGs generation 2.17 to 23.17% and ~60% H2S concentration.USDA-NIFA
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Romano, Natalie C. "Photophysical Properties of Amphiphilic Naphthalene Diimide Nanoassemblies and Cadmium Sulfide Nanoparticles and Poly(phenylene-ethynylene) Nanocomposites." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1399035654.
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Das, Prajna Paramita. "Enhancement of photoactivity by synthesizing nanotube-nanoparticle composites of TIO₂ and CdS for generation of hydrogen via splitting of water." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460754.
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Zemke, Jennifer M. 1983. "Surface Modification and Multiple Exciton Generation Studies of PbS Nanoparticles." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/12085.
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xx, 134 p. : ill. (some col.)Solar energy is a green alternative to fossil fuels but solar technologies to date have been plagued by low conversion efficiencies and high input costs making solar power inaccessible to much of the developing world. Semiconductor nanoparticles (NPs) may provide a route to efficient, economical solar devices through a phenomenon called multiple exciton generation (MEG). Through MEG, semiconductor NPs use a high-energy input photon to create more than one exciton (electron-hole pair) per photon absorbed, thereby exhibiting large photoconversion efficiencies. While MEG has been studied in many NP systems, and we understand some of the factors that affect MEG, a rigorous analysis of the NP-ligand interface with respect to MEG is missing. This dissertation describes how the NP ligand shell directly affects MEG and subsequent charge carrier recombination. Chapter I describes the motivation for studying MEG with respect to NP surface chemistry. Chapter II provides an in-depth overview of the transient absorption experiment used to measure MEG in the NP samples. Chapter III highlights the effect of oleic acid and sodium 2, 3-dimercaptopropane sulfonate on MEG in PbS NPs. The differences in carrier recombination were accounted for by two differences between these ligands: the coordinating atom and/or the secondary structure of the ligand. Because of these hypotheses, experiments were designed to elucidate the origin of these effects by controlling the NP ligand shell. Chapter IV details a viable synthetic route to thiol and amine-capped PbS NPs using sodium 3-mercaptopropane sulfonate as an intermediate ligand. With the versatile ligand exchange described in Chapter IV, the MEG yield and carrier recombination was investigated for ligands with varying headgroups but the same secondary structure. The correlation of ligand donor atom to MEG is outlined in Chapter V. Finally, Chapter VI discusses the conclusions and future outlook of the research reported in this dissertation. This dissertation includes previously published and unpublished co-authored material.
Committee in charge: Dr. Geraldine L. Richmond, Chairperson; Dr. David R. Tyler, Advisor; Dr. Mark C. Lonergan, Member; Dr. Catherine J. Page, Member; Dr. Hailin Wang, Outside Member
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Greene, Robert Crandall. "The separation of copper sulfide ore minerals from gangue using magnetic nanoparticles functionalized with peptides selected via phage display : a proof of concept." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61528.
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The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.Applied Science, Faculty of
Mining Engineering, Keevil Institute of
Graduate
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Al, Chaghouri Hanan. "Novel routes to the synthesis and functionalization of metallic and semiconductor thin films and nanoparticles." Thesis, University of Manchester, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.632330.
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The process of assembling metal nanoparticles at the interface of two liquids has received a great interest over the past few years due to a wide range of important applications and their unusual properties compared to bulk materials. The work in this thesis presents a low cost, simple and cheap synthesis of metal nanoparticles, core/shell structures and semiconductors followed by assembly of these particles between immiscible liquids. The aim of this thesis is divided to three parts (Summary of the experimental work of this thesis is in Table A1):1) To achieve a closed loop recycling for producing cadmium sulfide as powders and/or nanostructured thin films for solar cells or other optoelectronic devices applications. A series of bis(dialkyldithiocarbamato)cadmium(II) were used for this approach. Bis(dioctyldithiocarbamato)cadmium(II) complexes proved to be the optimal alkyl chain for this process. The approach can be extended to other metal sulfides such as those of Zn, Pb, Cu, or Fe and many transition metals and oxides.2) To explore the phenomena of exchange bias in very small size particles (5 nm) of Ni/NiO (core/shell structure) obtained by solution phase synthesis. Ferromagnetism (FM) due to exchange bias is well established in the case of larger particles with diameters over 10 nm. However, sub 10 nm magnetic structures synthesized by solution phase have never been found to be ferromagnetic at room temperature. These Ni/NiO nanocrystals with ferromagnetic properties at room temperature were among the smallest and strongest magnets made in solution. Similar magnets can be obtained using a rare class of high anisotropy materials nearly all of which feature precious metals. This work would lead to significantly cheaper magnetic particles suited for the mass market. The applications of this work can be applied to produce viable storage devices and the other possibility is to disperse these nanocrystals in solution and use it to make ferrofluids which have a number of mature applications. Functional device architectures of these particles were rapidly and inexpensively produced as thin films using self-assembly of liquid/liquid interface process at room temperature by using octylamine as a surfactant.3) To synthesise and assemble submicron particles of silver, cobalt and nickel by using polyol methods and liquid/liquid interface, respectively. The effect of reaction conditions (solvent, precursor concentration, temperature, etc.) on synthesis and assembly of the particles was studied. Assembled cobalt and nickel as films are promising materials for spintronics, magnetic and magneto-electronics and biomedics. The nature and characteristics of the particles and their films were studied by a number of techniques such as SEM, EDX, TEM, p-XRD, UV-Vis, PL, FTIR, DLS and SQUID for magnetic measurements.
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Tang, Lu. "Nanoparticules mimes des propriétés biologiques des GAGs : vers un inhibiteur sélectif de CXCL12." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS072.
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L'Héparane Sulfate (HS), un polysaccharide linéaire, module les activités biologiques de nombreuses protéines. Afin d'élucider les interactions entre l'HS et les protéines, la synthèse chimique d'HS est un outil précieux, mais elle peut être difficile. Notre équipe a montré que des mélanges combinatoires obtenus par auto-assemblage de différentes combinaisons de dérivés disaccharidiques (lactose et lactose persulfaté) sur surfaces planes d'or peuvent reconnaître spécifiquement certaines protéines se liant à l'HS, telles que les isoformes de la chimiokine CXCL12 ou IFNγ. Avec ces dérivés, nous avons réalisé un auto-assemblage sur des nanoparticules d'or. Mais à cause de la toxicité des nanoparticules d'or, nous avons aussi adapté cette méthode à des nanoparticules lipidiques. En utilisant les conditions qui ont déjà été améliorées pendant la synthèse des dérivés lactose et lactose persulfaté, nous avons préparé deux autres dérivés disaccharidiques plus proches de la structure réelle d'HS. Ces nouveaux dérivés sont utilisés pour réaliser des nanoparticules d'or et nanoparticules lipidiques afin de comparer les propriétés avec les lactose et lactose persulfaté. Les tests d'affinité avec différentes protéines sont en cours de réalisationHéparan Sulfate (HS) is a linear polysaccharide that modulates the biological activities of numerous proteins. In order to elucidate the interaction between HS and proteins, the synthesis of HS is an invaluable tool, but the synthesis is sometimes difficult. Our group has demonstrated that the combinatorial mixtures obtained by self-assembly of different combinations of disaccharide derivatives (lactose and persulfated lactose) on gold plan surfaces could recognize specifically some HS binding proteins, such as the isoforms of the chemokine CXCL12 or IFNγ. Because of the toxicity of gold nanoparticles, we have also adapted this method to lipid nanoparticles. Using the conditions that have already improved during the synthesis of lactose and persulfated lactose derivatives, we have synthesized two other disaccharide derivatives, which were closer to the real structure of HS. These new derivatives were used to prepare the gold and lipid nanoparticles at the aim of comparing the properties with lactose and persulfated lactose. The tests of affinities with different proteins are in progress
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El, Sayed Shehata Nasr Sameh. "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/52598.
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[EN] Abstract
The present PhD thesis entitled "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules" is based on the application of supramolecular chemistry and material science principles for the development of optical chemosensors for anions and neutral molecules detection.
The second chapter of this PhD thesis is devoted to the preparation of chemodosimeters for the chromo-fluorogenic detection of fluoride, diisopropyl fluorophosphates (DFP) and hydrogen sulfide. The optical detection of fluoride anion was achieved by using a pyridine derivative containing a t-butyldimethylsilyl ether group. Aqueous solutions of the chemodosimeter were colorless but turned yellow upon addition of fluoride anion. Also a remarkable enhancement in emission was observed only upon the addition of fluoride. The optical changes were ascribed to a fluoride-induced hydrolysis of the silyl ether moiety.
Also a chemodosimeter for the optical recognition of DFP, a nerve agent simulant, was prepared. In this case, the chemodosimeter was based on a stilbene pyridinium derivative functionalized with hydroxyl and silyl ether moieties. Aqueous solutions of the chemodosimeter were colorless changing to yellow upon DFP addition. The optical changes were ascribed to a hydroxyl phosphorylation followed by a fluoride-induced hydrolysis of the silyl ether group. Besides, that probe was implemented in test strips and DFP detection in gas phase was accomplished.
Finally, the fluorogenic recognition of hydrogen sulfide anion was explored. For this purpose different fluorophores were selected and fucntionalized with 2,4-dinitrophenyl ether groups. The prepared probes were neraly non-emissive but remarkable emission enhancements upon addition of hydrogen sulfide were observed. The emission enhancements observed were due to a selective sulfide-induced hydrolysis of the 2,4-dinitrophenyl ether moiety that yielded the free fluorophores. Another set of chemodosimeters equipped with azide and sulfonylazide moieties were prepared. Again these probes were non-fluorescent but upon addition of hydrogen sulfide an important enhancement in emission was found. The selective response was ascribed to a reduction of the azide and sulfonylazide moieties to amine and sulfonylamide induced by hydrogen sulfide anion. Besides, the viability assays showed that these dosimeters were essentially non-toxic and real-time fluorescence imaging measurements confirmed their ability to detect intracellular hydrogen sulfide at micromolar concentrations.
The third chapter of this PhD thesis was devoted to the preparation of nanoscopic gated materials and their use in sensing protocols. In a first step a gated material for the optical detection of glutathione (GSH) was prepared. For this purpose MCM-41 mesoporous silca nanoparticles were selected as inorganic scaffold. The pores were loaded with safranine O and the external surface was functionalized with disulfide-containing oligo(ethylene glycol) moieties. Dye delivery from aqueous suspensions of the sensory material was only observed in the presence of GSH. The signalling paradigm was ascribed to the selective reduction of the disulfide bond by GSH which induced pore opening and dye release.
Also capped organic-inorganic hybrid materials for the selective detection of hydrogen sulfide were prepared and characterized. In this case the same MCM-41 support was used and charged with [Ru(bipy)3]2+ dye. Then, the external surface was functionalized with Cu(II)-macorcyclic complexes and finally, the pores were capped by the addition of the bulky anion hexametaphosphate. Aqueous suspensions of this material showed negligible dye release whereas in the presence of hydrogen sulfide anion a remarkable colour change was observed. This optical response was ascribed to a demetallation process of the Cu(II) complex induced by hydrogen sulfide.[ES] Resumen La presente tesis doctoral titulada "Química supramolecular: Nuevos dosímetros químicos y materiales híbridos para la detección cromo-fluorogénica de aniones y moléculas neutras." está basada en la aplicación de principios básicos de la química supramolecular y de la ciencia de materiales en el desarrollo de sensores ópticos para aniones y moléculas neutras. El segundo capítulo de esta tesis doctoral está dedicado a la preparación de dosímetros químicos para la detección cromo-fluorogénica de fluoruro, diisopropil fluorofosfato (DFP) y sulfuro de hidrógeno. Para la detección óptica del anión fluoruro se sintetizó un derivado de piridina funcionalizado con un t-butildimetilsilil éter. En este capítulo también se describe la preparación de un dosímetro químico para la detección de DFP, que es un simulante de agentes nerviosos. Este dosímetro está basado en un estilbeno funcionalizado con una sal de piridinio que contiene grupos hidroxilo y silil éter en su estructura. Finalmente se prepararon dos familias de sensores para la detección óptica de hidrógeno sulfuro. La primera familia de sensores consiste en fluoróforos comunes funcionalizados con 2,4-dinitrofenil éteres. Los sensores preparados no presentaron una emisión de fluorescencia importante mientras que, en presencia del anión hidrógeno sulfuro, se observó un aumento significativo. La segunda familia de dosímetros también estaba compuesta por ciertos fluorofóros pero, en este caso, funcionalizados con grupos azida y sulfonilazida. Los dosimétros preparados, siguiendo esta segunda aproximación, tampoco dieron una fluorescencia significativa observándose un aumento de la misma al añadir el anión hidrógeno sulfuro. El tercer capítulo de esta tesis doctoral está dedicado a la preparación de materiales híbridos nanoscópicos funcionalizados con puertas moleculares y su aplicación en protocolos de reconocimiento. En primer lugar se preparó un material para la detección óptica de glutatión (GSH). Para ello se emplearon nanopartículas de MCM-41 mesoporosas como soporte inorgánico. Los poros del soporte fueron cargados con el colorante safranina O y la superficie externa funcionalizada con oligo(etilenglicol) conteniendo enlaces disulfuro. También se prepararon y caracterizaron varios materiales híbridos para la detección selectiva del anión hidrógeno sulfuro. En este caso también se empleó, como soporte inorgánico, sílice mesoporosa MCM-41. Los poros del soporte inorgánico fueron cargados con [Ru(bipy)3]2+ y la superficie externa funcionalizada con varios complejos macrocíclicos de Cu(II). El material sensor final fue obtenido al añadir el anion hexametafosfato, que compleja con los complejos de Cu(II), produciendo un bloqueo de los poros.
[CAT] Resum La present tesi doctoral titulada "Química supramolecular: Nous dosímetres químics i materials híbrids per a la detecció cromo-fluorogènica d'anions i molècules neutres." està basada en l'aplicació dels principis bàsics de la química supramolecular i de la ciència dels materials en el desenvolupament de sensors òptics per a anions i molècules neutres. El segon capítol d'aquesta tesi doctoral està dedicat a la preparació de dosímetres químics per a la detecció cromo-fluorogènica de fluorur, diisopropil fluorofosfat (DFP) i sulfur d'hidrogen. Per a la detecció òptica de l'anió fluorur es va sintetitzar un derivat de piridina funcionalitzat amb un t-dibutildimetilsilil èter. En aquest capítol també es descriu la preparació d'un dosímetre químic per a la detecció de DFP, que és un simulant d'agents nerviosos. Aquest dosímetre està basat en un estilbè funcionalitzat amb una sal de piridina que conté grups hidroxil i silis èter en la seua estructura. Finalment varen ser preparades dues famílies de sensors per a la detecció òptica de sulfur d'hidrogen. La primera família consisteix en fluoròfors comuns funcionalitzats amb 2,4-dinitrofenil èters. Els sensors preparats no presentaren una emissió de fluorescència significativa mentre que, en presencia de l'anió hidrogen sulfur, es va observar un augment significatiu. La segona família de dosímetres també estava composada per certs fluròfors però, en aquest cas, funcionalitzats amb grups azida i sulfonilazida. Els dosímetres preparats, seguint aquesta segona aproximació, tampoc donaren una fluorescència significativa observant-se un augment de la mateixa al afegir l'anió hidrogen sulfur. El tercer capítol d'aquesta tesi doctoral està dedicat a la preparació de materials híbrids nanoscòpics funcionalitzats amb portes moleculars i la seua aplicació en protocols de reconeixement. En primer lloc es va preparar un material per a la detecció òptica de glutatió (GSH). Per a aquest propòsit es varen emprar nanopartícules MCM-41 mesoporoses com a suport inorgànic. Els porus del suport varen ser carregats amb el colorant safranina O i la superfície externa funcionalitzada amb oligo(etilenglicol) que contenia enllaços disulfurs. També varen ser preparats i caracteritzats diversos materials híbrids per a la detecció selectiva de l'anió hidrogen sulfur. En aquest cas també es va emprar, com a suport inorgànic, sílice mesoporosa MCM-41. Els porus del suport inorgànic varen ser carregats amb [Ru(bipy)3]2+ i la superfície externa funcionalitzada amb diversos complexos macrocíclics de Cu(II). El material sensor final es va obtindre al afegir l'anió hexametafosfat, que es complexa amb macrocicles de Cu(II), produint un bloqueig dels porus.
El Sayed Shehata Nasr, S. (2015). Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52598
TESIS
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Gabriel, Stefanie. "Assessment of Lead Chalcogenide Nanostructures as Possible Thermoelectric Materials." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-128413.
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The assembly of nanostructures into “multi”-dimensional materials is one of the main topics occurring in nanoscience today. It is now possible to produce high quality nanostructures reproducibly but for their further application larger structures that are easier to handle are required. Nevertheless during their assembly their nanometer size and accompanying properties must be maintained. This challenge was addressed in this work. Lead chalcogenides have been chosen as an example system because they are expected to offer great opportunities as thermoelectric materials. Three different ways to achieve assemblies of lead chalcogenide nanostructures were used and the resulting structures characterized with respect to their potential application as thermoelectric material.
The first means by which a “multi”-dimensional assembly of lead chalcogenide quantum dots can be produced is the formation of porous structures such as aerogels and xerogels. A procedure, where the addition of an initiator such as oxidizers or incident radiation is unnecessary, is introduced and the formation process studied by absorption spectroscopy. The time-consuming aggregation step could be significantly reduced by employing a slightly elevated temperature during gelation that does not lead to any observable differences within the resulting gel structures. After either supercritical or subcritical drying, highly porous monolithic gel structures can be achieved. During the gel formation the size and the shape of the particles changed and they were directly linked together. Nevertheless the resulting porous structures remain crystalline and size dependent effects of the optical properties could be shown. Gels produced from a mixture of PbS and PbSe QDs show a homogenous distribution of both materials but it is not clear to what extent they form an alloy. Although the particles are directly linked together the resulting porous structures possess a very high resistivity and so it was not possible to characterize the semiconductor aerogels with regard to their thermoelectric properties. To achieve an enhanced conductivity porous structures containing PbS and Au nanoparticles have been produced. As has been seen for the pure semiconductor gels the size of the PbS quantum dots has increased and elongated particles were formed. In contrast to the PbS QDs the Au nanoparticles did not change their size and shape and are unevenly distributed within the PbS network. Through the use of the gold nanoparticles the conductivity could be increased and although the conductivity is still quite small, it was possible to determine Seebeck coefficients near room temperature for a mixed semiconductor-metal gel.
The second means by which QD solids could be formed was by the compaction of the QD building blocks into a material that is still nanostructured. Therefore the synthesis of PbS was optimized to achieve sufficient amounts of PbS quantum dots. The ligands used in the synthesis of the QDs unfortunately act as an insulating layer resulting in QD solids with resistivities as high as 2 Gigaohm. For this reason different surface modification strategies were introduced to minimize the interparticle distance and to increase the coupling between the QDs so as to increase the conductivity of the resulting quantum dot solids. One very promising method was the exchange of the initial ligands by shorter ones that can be destroyed at lower temperatures. By such heat treatments the resistivity could be decreased by up to six orders of magnitude. For the pressing of the quantum dots two different compaction methods (SPS and hydraulic pressing) were compared. While the grain growth within the SPS pressed samples is significantly higher the same densification can be achieved by a cold hydraulic pressing as well as by SPS. The densification could be further increased through the use of preheated PbS QDs due to the destruction of the ligands. Samples which had been surface modified with MPA and subsequently thermally treated show the best results with respect to their thermopower and resistivities. Nevertheless the conductivity of the QD solids is still too high for them to be used as efficient thermoelectric materials.
The final assembly method does not involve QDs but instead with one dimensional nanowires. Therefore a synthesis was developed that enables the formation of PbS nanowires of different diameters and one that is easy up-scalable. By the use of a less reactive sulfur precursor and an additional surfactant the formation of nuclei is significantly retarded and within an annealing time of two hours nanowires can be formed presumably by an oriented attachment mechanism. Single crystalline nanowires with a diameter of 65-105 nm could be achieved with the longest axes of the nanowires being parallel to [100]. The resulting nanowires were used as building blocks for film formation on glass substrates by an easily implemented method that requires no special equipment. To characterize the films with a view to their possible application as a thermoelectric material, surface modifications of the films were performed to improve the charge transfer in the films and the Seebeck coefficients of the resulting films measured. Therefore the previous approach of using MPA was applied and a subsequent thermal treatment demonstrated very promising results. In addition an crosslinking ligand was used for surface treatment that leads to similar results as was observed for the thermally treated MPA approach. Both approaches lead to an order of magnitude decrease in the resistivity and due to the fewer grain boundaries present in the films composed of nanowires as compared to the QD assemblies the conductivity is significantly higher. The Seebeck coefficient measurements show that the thermal treatment only slightly affects the Seebeck coefficients. Therefore a significantly higher power factor could be achieved for the nanowire films than for the QD solids.
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Mullaugh, Katherine M. "Formation and persistence of cadmium sulfide nanoparticle in aqueous solution." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 232 p, 2009. http://proquest.umi.com/pqdweb?did=1885682071&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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See, Erich Michael. "Modeling Plasmon Resonance for a Gold Nanoparticle Plasmon-Enhanced Cadmium Sulfide Biosensor." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1249499557.
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Leyral, Géraldine. "Synthèse et structuration de sulfure de molybdène promu nickel en présence de liquide ionique ou de polymère hydrosoluble amphiphile : application en catalyse hétérogène." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20266.
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Avec l’épuisement progressif des ressources pétrolières, la production de biocarburant est actuellement en plein développement. Utiliser la biomasse en tant que source d’énergie permettrait également de limiter la concentration en dioxyde de carbone dans l’atmosphère et ainsi l’effet de serre. Cependant son processus de transformation implique une étape d’hydrodésoxygénation qui nécessite d’avoir recours à des catalyseurs de type sulfure de molybdène dopé par du cobalt ou du nickel. Ces catalyseurs sont également indispensables au cours du traitement du pétrole lors du procédé d’hydrodésulfuration qui est primordial pour limiter la pollution de l’air par les gaz de combustion des carburants. Cette thèse propose une méthode de synthèse et de structuration de catalyseurs massiques NiMoS facile à mettre en œuvre et rapide. Deux solvants ont été utilisés : l’eau et le formamide. L’ajout d’un polymère hydrosoluble amphiphile, le PEO113-b-PLLA32, dans l’eau et de liquides ioniques (BMIMNTf2 et BMIMBF4) dans le formamide ont permis la structuration des matériaux et l’obtention de surfaces spécifiques atteignant 55 m2g-1. Ceci représente une surface importante pour ce type de composé, en particulier dans le cadre d’une synthèse par chimie douce. Les premiers tests catalytiques réalisés vis-à-vis de la réaction d’hydrodésoxygénation de l’acide décanoïque montrent une activité catalytique très prometteuse pour ces matériauxWith the progressive decrease of oil resources, the production of biomass fuel is a fast growing field. This could limit the concentration of carbon dioxide in the atmosphere and thus the global warming. The production of this kind of fuel requires the use of catalysts such as nickel or cobalt promoted molybdenum sulfide. These materials are also crucial during the refining of oil, an essential step to limit atmospheric pollution during the classic fuel combustion. New methods to synthesize and structure NiMoS catalysts have been developed in this work. Two solvants have been studied: formamide and water. The addition of an amphiphilic water-soluble polymer (PEO113-b-PLLA32) in water and of ionic liquids (BMIMNTf2 and BMIMBF4) in formamide led to the structuring of the materials with specific surface areas up to 55 m2g-1. This is a high value for this kind of material, especially since the synthesis is carried out under soft conditions. The first catalytic tests dealt with decanoïc acid hydrodesoxygenation and highlighted a promising activity for these materials
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Cisse, Seydou. "Use of Biopolymer Entrapped Sulfate Reducing Bacteria and Metal Nanoparticles for Effective Aqueous Sulfate Removal." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/27234.
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Sulfate reducing bacteria (SRB) isolated from activated sludge were used to investigate sulfate removal from aqueous solution using calcium alginate entrapped SRB in batch studies with ethanol and lactose as the carbon sources. The interferences of pH, temperature, Al3+, Cu2+, and Zn2+ on sulfate removal were also investigated. Further, sulfate removal experiments were conducted with co-entrapped SRB and nanoscale zero-valent iron (NZVI) and separately entrapped SRB and NZVI. Results indicate that EntSRB can effectively remove sulfate from aqueous solution. 88-95% sulfate removal was achieved. Both ethanol and lactose worked well as carbon sources for entrapped bacteria. Interference studies indicated low sulfate removal in the presence of 25-50 mg/L of aluminum and zinc. Low pH (pH≤ 4) and low temperature (5?C) decreased sulfate reduction. NZVI appeared to have negative effects on SRB. Loading of 0.05 and 0.1 g of NZVI led to lower SO42- removal as compared to experiments without NZVI.Fulbright Program Fellowship
National Science Foundation (NSF, Grant: CCMI-1125674)
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Whyte, John Morrison. "Surfactant-inhibited barium sulphate nanoparticles for use in drilling fluids." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231876.
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This project studied the production of barium sulphate nanoparticles through inhibition of crystal growth, during precipitation, by different surfactants. Barium sulphate is the pure form of the ore baryte, which due to its high density and softness, is the most commonly used additive used to increase the density of drilling fluids. A non-agglomerating, stable nano-scale dispersion of barium sulphate particles would have significant technical and commercial impact in the drilling fluids industry. This thesis tested the possibility of precipitating barium sulphate and restricting its crystal growth with inhibitors, creating nanoparticles. Six inhibitors were tested; dodecanoic acid, palmitic acid, stearic acid, adamantane carboxylic acid, methylnonanoic acid and a mixture of phosphate esters known commercially as Fazewet. Precipitated, inhibited barium sulphate was characterised using powder XRD, DRIFT FTIR and solid-state NMR (SSNMR). All inhibitors were shown to form single-phase, orthorhombic barium sulphate crystals proving that the inhibitors affect only the surfaces of precipitated crystals and do not enter the crystal lattice. FTIR allowed the relative adsorbed concentration of each inhibitor to be assessed. The results indicate that adsorbed inhibitor increases with increasing inhibitor concentrations but that their attachment is not proportional to the concentration. In most cases concentrations of 0.1mol l-1 of inhibitor were sufficient to saturate the crystal surface. SSNMR also agreed with this although the sample size was too small, due to equipment restrictions, to make definitive conclusions. Through the use of the Debye-Scherrer equation, the crystallite size was calculated and showed that at concentrations of 0.2mol l-1 all inhibitors other than palmitic acid produced nano-scale (< 100nm) crystallites. Further analysis showed that further reductions could be achieved through precipitation in an alkaline pH environment, with the application of mechanical shear and by using adding 50% v/v of ethanol. iv Laser diffraction particle size analysis showed that the dominant factor in reducing particle size distribution was inhibitor concentration. The volume-based PSD used by the laser diffraction system was considered to distort excessively the particle sizes present and so analysis switched to dynamic light scattering. DLS showed that dodecanoic acid, palmitic acid and stearic acid, despite forming nano-scale crystallites, could not produce a nano-scale dispersion of barium sulphate and as such were unsuitable for use in drilling fluids. Stable nano-scale dispersions were found to have been formed when inhibited with adamantane carboxylic acid, methylnonanoic acid and Fazewet. DLS also confirmed that dispersed particle size rather than simply crystallite size could be reduced with an alkaline pH and high mechanical shear. Concentration was still the dominant effect, however with the smallest particles sizes (ZAvg) being observed at concentrations of 0.6mol l-1. The particle sizes for the three modifiers were approaching that of the crystallite size, suggesting that some further reduction is possible, but large reductions are unlikely. All three inhibitors produced sub 100nm ZAvgs, with the smallest produced by methylnonanoic acid of 43nm. Spherical nanoparticles were observed through the use of ESEM and TEM. Due to equipment time restrictions only 0.2mol l-1 treatment levels could be examined, but ESEM showed apparent nanoparticle clusters, later confirmed using pixel count and SFDA methods. TEM analysis showed discrete particles as small as 3nm, indicating that the lower limit for achievable particle size may be lower than PSD measurements would suggest. The results indicate that adamantane carboxylic acid, methylnonanoic acid and Fazewet sufficiently inhibit crystal growth to be potential candidates for the production of barium sulphate nanoparticles. These three inhibitors produce a barium sulphate dispersion that is stable and nano-scale even after drying and redispersion.
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Clarke, Emma Victoria Faye. "An investigation into silver nanoparticles removal from water during sand filtration and activated carbon adsorption." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/29959.
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Wastewater treatment plants (WwTP) act as the principle buffer between anthropogenic sources of Silver Nanoparticles (AgNPs) and environmental targets. AgNPs, given their effective anti-microbial properties, have the potential to negatively impact WwTP processes and organisms within the natural environment. A clear understanding of the fate and transport of AgNPs as they pass through WwTPs is crucial in evaluating AgNPs impacts for WwTP process, the natural environment and in the development of a comprehensive environmental risk assessment for AgNPs. The main aim of this thesis was to carry out an analysis on the fate, transport and transformation of AgNPs through WwTP relevant filtration medias in order to understand more about the toxicological implications for both WwTP processes and receiving environments. AgNPs were synthesised in-house, via an in-situ reduction method, which produced a homogeneous dispersion of nanoparticles of average particle diameter 9.98nm, with a standard deviation of 3.11nm. Column studies and adsorption isotherm experiments were conducted to investigate the fate and transport of silver nitrate, AgNPs and bulk silver across media beds of quartz sand and granulated activated carbon (GAC), both chosen for their relevance in wastewater treatment protocols. TEM imaging and EDS analysis was employed to characterise the AgNPs physically and elementally within the column influents and effluents. An original contribution made to the existing knowledge on AgNPs is that in contrast to bulk silver and silver nitrate, uncoated AgNPs were observed to be highly mobile through the quartz sand media. This high mobility was in contrast with the prior expectation that van der Waals forces of attraction between the positively charged AgNPs and the negative charge of the silica surfaces within the sand bed would lead to some measure of retention within the column matrix. The resulting high mobility of the AgNPs was attributed to particle surface contamination of boride ions originating from the reduction agent used during the synthesis process. This highlights (and reinforces) the importance of better understanding on the implications of the various methods of synthesis and use of capping agents for AgNPs characteristics and the impact this has on fate and transport. AgNPs were also noted to have been significantly altered after their passage through the quartz sand media, with up to 83% of the sample increasing in size, from 9.98nm to an average of 18.26nm and a maximum of 144nm. Particle size measurements were made using the measuring tool available in the GNU Image Manipulation Program (GIMP). This size increase was attributed to the formation of nano-alloy clusters with residual gold and iron compounds, naturally present within the sand bed. In the case of silver-gold alloy clusters, this is expected to exhibit positive implications for future environmental fates of the resulting AgNPs, where the presence of gold in alloy clusters has been observed to significantly deactivate AgNPs silver ion release. In contrast to the sand, it was observed that the GAC was an effective absorber of AgNPs. However, this was observed to be a size dependant relationship, where the GAC was not observed to be effective for adsorption of bulk silver at particle sizes of 300 – 800nm. In this thesis, in addition to the experimental work, a novel, low complexity technique was developed for the detection and quantification of AgNPs in laboratory aqueous solutions. This protocol utilises a laboratory bench top photometer and gave AgNPs concentration results that reliably and accurately reflected that of ICP-MS and ICP-OES results within a detection range of 0.01 and 20mg/L; where the correlation coefficient between the instrument absorbance response and ICP-MS/OES concentration (at 450nm) was R2 0.994.
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Riddin, Tamsyn Louise. "Investigating the enzymatic mechanism of platinum nanoparticle synthesis in sulfate-reducing bacteria." Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1004024.
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Efforts to discover an efficient yet environmentally friendly mode of metal nanoparticle (NP) synthesis are increasing rapidly. A ‘green’ route that avoids the high costs, toxic wastes and complicated protocols associated with chemical synthesis methods is therefore highly sought after. A biologically based protocol will provide the possibility of gaining control over the mechanism merely by manipulating the experimental conditions of the system. Given that the properties of nanoparticles are highly dependant on the morphology of the particles themselves, this mechanistic control will provide significant industrial advantages with regards to tailoring specific properties of the nanoparticles produced. The key objectives of this study were to: a) determine whether a consortium of sulfate-reducing bacteria was capable of platinum nanoparticle synthesis, b) elucidate the bioreductive, enzymatic mechanism responsible, and c) attempt to control the morphologies of the particles produced. A consortium of sulfate-reducing bacteria (SRB), isolated from sewage sludge, was used in these investigations due to the advantages a consortium provides in comparison to pure cultures. The syntrophic relationships established within the constituent species not only prevent the growth of contaminant microbes, but increases the oxygen-tolerance of the system as a whole. The sulfate-reducing consortium was shown to possess an aerobic mechanism for Pt(IV) reduction which, though different from the anaerobic bioreductive mechanism previously identified in literature, did not require an exogenous electron donor. It was demonstrated that the Pt(IV) ion becomes reduced to Pt(0) via a two-cycle mechanism involving Pt(II) as the intermediate. Further investigation elucidated the reduction of Pt(IV) to Pt(II) to be dependant on a novel Pt(IV) reductase which becomes upregulated in the presence of Cu(II), while the reduction of Pt(II) to Pt(0) occurred by means of a periplasmic hydrogenase. To our knowledge, this is the first time a coupled mechanism for Pt(IV) reduction by micro-organisms has been proposed. A cell-free, crude protein solution from the consortium produced both geometric and irregular platinum nanoparticles. The wavelength of 334 nm was chosen as a nonquantitative indicator of Pt(0) nanoparticle formation over time. The optimum conditions for nanoparticle synthesis were pH 9.0, 65 ˚C and 0.75 mM Pt(IV) as H2PtCl6 salt. In the absence of a buffer a Pt(IV) concentration > 1 mM resulted in the precipitation of protein-nanoparticle bioconjugates, due to unfavourable acidic conditions. This demonstrated that the nanoparticles were binding to and becoming stabilised by general protein in the cell-free solution. Upon addition of a sodium-bicarbonate buffer, a general increase in Pt(IV) reduction to Pt(II) was observed. The addition of the buffer also resulted in an unexplained change in particle morphology and for this reason was not used in subsequent investigations. Polyvinylpyrrolidone (PVP) was shown to compromise the reduction rate of the Pt(IV) ion by SRB cells. The presence of extracellular NP’s was suggested by the colour of the supernatant turning brown and the A334 increasing over time. Attempts to visualise the particles by transmission electron microscopy (TEM) resulted in an unexpected phenomenon where nanoparticles could be observed to form dynamically upon irradiation by the electron beam. Extended irradiation by the electron beam also resulted in structural changes of the particles occurring during observation. An increase in temperature was shown to increase the reduction rate which in turn resulted in particles decreasing in size. The starting pH was shown to have a significant effect on the reduction rate and particle morphology although specific trends could not be identified. In conclusion, the cell-soluble extract from the sulfate-reducing consortium investigated, is capable of Pt(0) nanoparticle synthesis. Precise control over the particle morphology was not attained although the mechanism was further clarified and optimal conditions for nanoparticle synthesis were determined.
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Dedeh, Amina. "Impact d'un sédiment dopé aux nanoparticules d'or ou de sulfure de cadmium sur un invertébré et un poisson d'eau douce." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0068/document.
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Le but de cette thèse était de déterminer l’impact de deux types de nanoparticules métalliques (sulfure de cadmium – CdS - et or - Au) sur deux organismes aquatiques modèles (vers tubifex et poisson zèbre Danio rerio). L’approche a consisté à doper le sédiment de la Garonne avec les deux types de nanoparticules et caractériser l’effet de cette contamination sur les deux organismes en utilisant plusieurs marqueurs à différents niveaux d'organisation biologique (réponses biochimiques, activité de neurotransmission, génotoxicité, expression génétique et activité de bioturbation). Les effets ont été évalués après exposition aux sédiments contaminés dans des systèmes expérimentaux de types microcosmes durant une vingtaine de jours. Dans un certain nombre de cas, ce travail a révélé un effet des nanoparticules qui n’était pas dû au métal mais aux propriétés nanoparticulaires. En effet, dans le cas des nanoparticules de CdS, nous avons observé des altérations du génome ainsi que la modification de l’activité de bioturbation des vers tubifex en réponse à la contamination aux nanoparticules mais pas à celle de la forme ionique. Dans ce travail nous avons pu observer le relargage des nanoparticules d’or depuis le sédiment vers la colonne d’eau, et sa biodisponibilité potentielle pour les poissons. Ces nanoparticules provoquaient des altérations de l’ADN chez les deux organismes, la modification de l’expression de certains gènes et l’augmentation de l’activité de l’acétylcholinestérase chez le poisson zèbre. Les résultats de bioturbation n’ont pas montré d’effets des nanoparticules d’or sur le mouvement des versThe aim of this thesis was to determine the impact of two types of metal nanoparticles (cadmium sulphide - CdS - and gold - Au) on two aquatic models (tubifex worms and zebrafish Danio rerio). The approach has been to dope the Garonne sediment with the two types of nanoparticles and characterize the effect of this contamination on the two animals using multiple markers at different levels of biological organization (biochemical responses, neurotransmission activity, genotoxicity, gene expression and bioturbation activity). The effects were evaluated after exposure to contaminated sediment in experimental microcosms systems for twenty days. In a number of cases this work revealed an effect of the nanoparticles that was not due to metal but to the nanoparticulate properties. Indeed, in the case of CdS nanoparticles, we observed alterations in the genome as well as the modification of the bioturbation activity of worms tubifex in response to the contamination of nanoparticles but not to that of the ionic form. In this work we observed the release of gold nanoparticles from the sediment into the water column, and its potential bioavailability to fish. These nanoparticles were causing DNA damage in both organisms, modifying the expression of certain genes and increased acetylcholinesterase activity in zebrafish. Bioturbation results showed no effects of gold nanoparticles on the movement of worms
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Nqakala, Zimkhitha Biancah. "Synthesis of DMSO based silver nanoparticles for application in wound healing." University of Western Cape, 2021. http://hdl.handle.net/11394/8233.
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>Magister Scientiae - MScSilver nanoparticles (AgNPs) apart from being chemically significant, have shown a lot of health benefits, the most studied being their anti-bacterial and anti-inflammatory properties. These biological properties can be further enhanced by adding compounds with known medical properties giving rise to even more desired potent materials. Anti-bacterial and cytotoxicity studies show that these AgNPs can kill bacteria, prevent infections and regenerate skin cells. On the other hand, previous studies have reported dimethyl sulfoxide (DMSO) with attractive wound healing abilities specifically cell growth promotion. It was then envisaged that the combination of DMSO and AgNPs could lead to a potent wound healing agent. It is a well-known fact that non-healing wounds pose a socioeconomic threat to a large population worldwide.
2023
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Salajková, Zita. "Plazmonicky aktivní elektrochemické elektrody na bázi nanotrubic sulfidu wolframičitého pokrytých zlatými nanočásticemi." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-320220.
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When an electromagnetic wave illuminates metal nanostructure under right circumstances, it can couple to the motion of electrons and thus give rise to so-called LSPR. When these collective oscillations non-radiatively decay, they excite charge carriers that can have, for a short moment of time, highly non-thermal energy distribution. These so-called "hot" electrons and holes can then take part in photochemical applications, e.g. in reactions on photoactive electrodes where hot electrons act as catalysts. Gold nanoparticles seem to be a good candidate for fabrication of such electrodes because they exhibit resonantly enhanced absorption due to plasmon excitation in the visible and near infrared spectral range, which could make the solar energy harvesting more efficient. In this work we present electrohemical experiments that should help to clarify the underlying principles of photochemical reactions involving hot electrons. Our model system consists of indium tin oxide electrodes covered with tungsten disulphide nanotubes that were previously decorated by gold nanoparticles. By comparing the results of chronoamperometric measurements on individual components of this system it was shown that excitation of plasmonic nanoparticles indeed leads to photocurrents and that electrochemical methods can serve as a valuable tool for analysis of photochemical reactions catalyzed by hot electrons.
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Rahman, Md Mahbubur. "Durability of nano-modified fly ash concrete to external sulfate attack under different environmental conditions." Canadian Society for Civil Engineering (CSCE), 2014. http://hdl.handle.net/1993/24055.
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There are still research gaps regarding the effects of key parameters such as water-to-cementitious materials ratio (w/cm), type of binder and pore structure characteristics on the response of concrete to special forms of sulfate attack: physical salt attack (PSA) and thaumasite sulfate attack (TSA). Hence, this study aims at developing an innovative type of concrete: nano-modified fly ash concrete, incorporating various dosages of nano-silica (NS) or nano-alumina (NA) and fly ash, and explores its efficiency in resisting various forms of sulfate attack.
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Yun, Seonguk. "Sulfur Tolerant Supported Bimetallic Catalysts for Low Temperature Water Gas Shift Reaction." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573224656177825.
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Moussaoui, Myriam. "Elaboration et caractérisations de nouveaux matériaux diélectriques structurés par des nanoparticules de sulfure de zinc : applications prospectives." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4001.
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Ce travail de thèse a pour objectif la création d’indice optique local et contrôlé dans une matrice vitreuse à travers la mise au point et le développement de procédés de synthèse de nanoparticules (NPs) de sulfure de zinc (ZnS) dans un verre d’oxydes. Nous avons commencé par l’élaboration par voie de fusion d’un verre d’oxydes de composition initiale très simple. Nous avons ensuite examiné la problématique de la synthèse et du contrôle de croissance des NPs de ZnS dans nos échantillons dans trois matrices différentes et par trois traitements : recuit thermique, insolation UV ou par un traitement simultané (recuit thermique + insolation UV). Les propriétés optiques des verres dopés NPs ZnS fabriqués ont été caractérisées par diverses techniques (absorption UV visible, photoluminescence, FTIR, Raman, XPS, mesure d’indice). Il ressort de ces caractérisations que nous arrivons à fabriquer des NPs dans les trois matrices dont la taille peut aller de 1.8 à 7 nm. La dispersion sur les distributions de taille dépend de la matrice, du traitement post-fusion et de sa durée ainsi que de la concentration initiale en dopant. Nous avons également été amené à synthétiser et à étudier des nanopoudres de ZnS. Le procédé de sélection de taille révèle qu’il est possible d’obtenir au moins trois distributions étroites de tailles bien distinctes. Des filtres optiques UV à bande étroite peuvent ainsi être réalisés pour une longueur choisie en contrôlant la taille des NPs ZnS. Des applications prospectives des NPs ZnS pour le nano marquage et la photo dégradation de polluants modèles présents dans l’eau ont été illustréesOur efforts have been devoted to the development of simple approach to synthesize ZnS nanoparticules (NPs) by melting process in a glassy matrix with the aim to create a controlled optical index variation. In this thesis, we present the formation of ZnS NPs in the glassy matrix and study of their optical properties. The nanocomposite incorporating ZnS in the host medium was prepared using the melting process from a mixture of the raw materials. We have prepared various glass samples with ZnS NPs size ranging from 1.8 à 7 nm. These samples were treated (heat treatment ± UV insulation with 244 nm laser) and characterized by UV-Vis absorption, FTIR, photoluminescence spectroscopy, Raman measurements and XPS. The refractive index measurements of these nanostructured composite glasses have been carried out and show an important increase with ZnS concentrations and treatments. We also present the elaboration of small and monodisperse ZnS nanopowder with size ranging from 3 to 100 nm by a simple, low-cost and mass production chemical method. The NPs were characterised by X-ray powder diffraction (XRD), UV-vis absorption and photoluminescence spectroscopy. The photocatalytic activity of ZnS nanopowders was investigated by using different colorant water dispersed. ZnS NPs appear to be a good candidate for potential environmental applications such as water purification. We also present application of fluorescent ZnS nanoparticles as cellular biomarkers. Fluorescent microscopy images of osteoblastic MC3T3-E1 cells revealed that the ZnS nanoparticles were biocompatible and were penetrated cells and nucleus regardless of their size. Hence, the ZnS NPs can be good candidates for drug delivery and bio-imaging applications
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Holzhausen, Cornelia [Verfasser]. "Anti-Inflammatory Dendritic Polyglycerol Sulfate Nanoparticle: Biodistribution, Elimination, Cellular Localisation and Toxicopathology in Mice / Cornelia Holzhausen." Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1140761439/34.
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Raulin-Woznica, Katarzyna. "Étude du dopage par des ions actifs et des nanoparticules semi-conductrices de matériaux sol-gel pour l'optique : interaction dopant-matrice et croissance localisée de nanoparticules par irradiation laser." Thesis, Lille 1, 2008. http://www.theses.fr/2008LIL10100/document.
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Ce travail concerne le dopage par des ions actifs et/ou des nanoparticules (NPs) semi-conductrices de CdS et la caractérisation de xérogels de SiO2 poreux obtenus par voie sol-gel. Le but de cette étude est de contribuer à la compréhension de l'effet du dopage sur les propriétés structurales, texturales et optiques du matériau final. Nous avons montré par spectroscopie Raman et absorption-désorption d'azote que l'incorporation d'ions actifs, tels que Cd2+, Pb2+ ou Eu3+, modifie les cinétiques et les mécanismes de la gélification et la densification du réseau de SiO2. La nature même de ces modifications est fonction de la concentration en ions dopants. Dans le cas de l'ion Eu3+, l'analyse a été complétée par la spectroscopie d'émission utilisant cet ion comme sonde luminescente. Des xérogels de SiO2 ont aussi été post-dopés avec des NPs de CdS. La méthode consiste à diffuser dans la matrice poreuse une solution aqueuse contenant les précurseurs de cadmium et du soufre. Les NPs cristallisent ensuite in situ de manière homogène sous traitement thermique. Les spectroscopies d'absorption UV-visible, d'émission et d'excitation ont montré l'influence des niveaux pièges liés à des défauts de surface des NPs sur leurs propriétés optiques et ont mis en évidence un transfert d'énergie lors du co-dopage de SiO2 par CdS :Eu3+. Une deuxième technique de croissance cristalline a été utilisée. Elle consiste à irradier, par un faisceau laser pulsé, les matrices sol-gel contenant les précurseurs de CdS pour former localement des microstructures de NPs. Nous montrons notamment que l'absorption à deux photons permet d'envisager la structuration à l'échelle submicronique des NPs de CdSThis work concerns the elaboration by sol-gel process and the characterization of porous SiO2 xerogels doped with active ions and/or with semiconducting nanoparticles of CdS. The aim of the study was to contribute to the comprehension of the doping effects on structural and optical properties of the final material. We showed by Raman spectroscopy and nitrogen absorption-desorption that the insertion of active ions, such as Cd2+, Pb2+ or Eu3+, changes the kinetics and the mechanisms of the gelation and densification of the network of SiO2. The choices of the pH and of the concentration of the doping ion have distinct effects on the kinetics. This study was completed by emission spectroscopy using Eu3+ ion as luminescent probe to describe the environment of this ion in the porous matrix. The SiO2 xerogels were post-doped with CdS nanoparticles. The post-doping technique consists in the diffusion of an aqueous solution containing cadmium and sulphur precursors in the porous matrix. The nanoparticles crystallize in situ by heat treatment. The nanoparticle size and their emission properties were determined by UVvisible absorption as well as emission and excitation spectroscopies. The results showed the influence on optical properties of trap levels introduced by the surface defects of nanoparticles and an enhancement of the Eu3+ emission in SiO2 xerogel co-doped with CdS :Eu3+. A second method for the formation of CdS nanoparticles was used. CdS microstructures were created locally by pulsed laser irradiation of sol-gel matrices containing the CdS precursors
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Le, Bars Maureen. "Devenir du zinc des produits résiduaires organiques après méthanisation et recyclage agricole : rôle des nanoparticules de sulfure de zinc." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0034.
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Le recyclage agricole de Produits Résiduaires Organiques (PROs) bruts ou après un traitement tel que la méthanisation et/ou le compostage est une pratique répandue. Il est indispensable d’évaluer l’impact environnemental de l’épandage des PROs après méthanisation, technologie en essor, en particulier vis-à-vis du zinc (Zn). La spéciation du Zn dans le PRO est un paramètre crucial pour établir le risque. Nous avons pu mettre en évidence que la méthanisation favorise la formation de nanoparticules de sulfures de Zn (nano-ZnS), qui est donc la forme majoritaire du Zn dans les digestats de méthanisation (>70%). Cette forme du Zn est instable car elle se transforme lors du compostage des digestats. Les paramètres structuraux des nano-cristaux (taille, contrainte) peuvent expliquer leur réactivité. Nos résultats montrent que plus les nano-ZnS sont petites et plus leur contrainte est importante. De plus, l’interaction avec les groupements thiols de certaines molécules organiques, potentiellement présentes dans un digesteur de méthanisation, relâche la contrainte des nano-ZnS et contrôle leur croissance. Enfin, les caractéristiques du sol amendé ont un rôle majeur pour le devenir des nano-ZnS: les composants de sols argileux riches en oxydes de fer sont capables de retenir le Zn issu de la dissolution des nano-ZnS, contrairement à ceux d’un sol sableux. Ce travail apporte une meilleure compréhension de la dynamique du Zn dans les écosystèmes cultivés soumis à l’épandage de PROsAgricultural recycling of organic waste (OW), raw or after a treatment like anaerobic digestion (AD) and/or composting is common. It is necessary to assess the environmental impact of OW agricultural recycling after anaerobic digestion since this technology is gaining interest, particularly regarding zinc, an abundant element in OW. In order to properly evaluate the risk, zinc speciation must be known. First, we have shown that AD promote the formation of nano-ZnS that is therefore the main species of Zn (> 70%) in AD digestates. This unstable species is transformed during composting of 1 to 3 months. Size and strain are parameters that can explain nanocrystals reactivity. We showed that the more nano-ZnS are small and the higher the strain is. Interaction with thiol containing organic molecules, potentially present in anaerobic digesters, release nano-ZnS structural strain and control its growth. Finally, amended soil characteristics have a key role for nano-ZnS fate: the components of clayey and iron-oxide-rich soils are able to immobilize Zn released by nano-ZnS dissolution, unlike sandy soils components. This work gives a better understanding of zinc dynamics in cultivated ecosystems subject to spreading of organic waste
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Keller, Jana [Verfasser]. "Biokinetics and inhalation toxicity of cerium dioxide and barium sulfate nanoparticles after 1, 4, 13 and 52 weeks of exposure / Jana Keller." Gießen : Universitätsbibliothek, 2015. http://d-nb.info/1078849315/34.
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Liu, Ruiqiang Zhao Dongye. "Fate, transport, and environmental availability of Cu(II) applied in catfish aquaculture ponds and enhanced immobilization of soil-bound lead using a new class of stabilized iron phosphate nanoparticles." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2006%20Fall/Dissertations/LIU_RUIQIANG_19.pdf.
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Yuan, Yuan. "Regulatory Effect of Elastin Based Biomaterial on Cellular Behavior and Its Application on Wound Repair and Regeneration." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6159.
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Elastin-like peptides (ELPs) are stimulus-responsive protein-based polymers which are attractive material for biomedical research due to their biocompatibility and unique properties. The physical properties of ELPs are dependent on the chain length and the chosen amino acid at the guest residue position. This imparts unlimited flexibility in designing ELP based biomaterials with the desired physical properties.
We have shown that in addition to their physical properties, ELPs have biological activities that are conducive to tissue regeneration. Specifically, we found that ELPs induce fibroblast proliferation via cell surface heparan sulfate proteoglycans (HSPG). Furthermore, our data suggests that ELP based materials with differential proliferative potential can be designed by controlling the interaction of ELPs with HSPGs by incorporating either hydrophobic or positively charged residues within the ELP sequence. Fibroblast proliferation is important for granulation tissue formation which is important in chronic wounds as well as in healing of other tissues. The customizable biological activity of ELPs coupled with their unique physical properties will enable us to design novel, sustainable and cost effective therapies for different tissue regeneration applications.
ELPs can be genetically fused to biologically active peptides or proteins. These fusions can be expressed and readily purified since they maintain the phase transitioning property of the fused ELP domain. Moreover, depending on the ELP sequence chosen the chimeric fusion sequences can self-assemble into unique structures such as nanoparticles. These structures can then be applied to the injury site where they not only provide unique topographical cues or structural support but also act as delivery vehicles for the fused bioactive protein. We developed a multifunctional nanoparticle that is comprised of PMP-D2-ELP fusion protein and different functional peptide ELP fusion proteins to preserve the bioactivity of the functional group with the existence of elastase. These heterogeneous particles will be beneficial for the delivery of combination therapies to solve multiple problems that often existed in chronic wound healing or other tissue regeneration process.
In summary, this study adds to our understanding of the biological activity of ELP and the interaction mechanism that allow the regulation of cellular behavior. Furthermore this work also investigated the potential therapeutic application of ELP as a delivery platform for chronic wound healing.
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Zatta, Kelly Cristine. "Desenvolvimento de um sistema terapêutico micro-/nanoestruturado contendo 5-fluorouracil para administração pulmonar." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/149501.
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A inexistência de um agente terapêutico único satisfatório para o tratamento do melanoma metastático e a potencialidade do quimioterápico 5FU (5-fluorouracil) motivou esta pesquisa, a qual teve por objetivo o desenvolvimento tecnológico de sistemas carreadores micro-/ e nanoestruturados contendo 5FU a fim de aumentar sua eficácia terapêutica e reduzir a toxicidade por meio da administração pulmonar. Duas formulações pulverulentas foram desenvolvidas com polímeros naturais, sulfato de condroitina e hidroxipropil-metil-celulose, denominadas 5FU-MS e 5FU-NS, utilizando as técnicas de aspersão e atomização vibracional piezoelétrica, respectivamente. Ambas as formulações foram avaliadas quanto às características físicas e químicas, perfil toxicológico in vivo (C. elegans e em ratos Wistar), e penetração e biodisponibilidade no tecido pulmonar pela quantificação da fração livre de fármaco por microdiálise pulmonar. A análise físico-química revelou a obtenção de partículas micrométricas para 5FU-MS e submicrométricas para 5FU-NS, com diâmetros médios de partícula de 2,546 ± 0,07 m e 0,652 ± 0,03 m, e fração respirável (FR%) de 55,12 ± 2,98 e 76,84 ± 0,07, respectivamente. Ambas demonstraram características e propriedades adequadas para administração pulmonar, com capacidade de deposição nas porções média e profunda. A toxicidade das formulações avaliada em C. elegans considerou o percentual de morte, desenvolvimento, DL50 e produção de ROS para os nematodos sob tratamento agudo e crônico. Os resultados evidenciaram redução significativa da toxicidade proporcionada pela redução da taxa de morte e maior desenvolvimento dos grupos tratados com as formulações 5FU-MS e 5FU-NS em comparação ao fármaco livre, sugerindo perfis de segurança satisfatórios para administração. Além disso, 5FU-MS revelou-se um agente pró-oxidante, representando um diferencial promissor deste sistema, podendo alcançar maior sensibilização das células tumorais com menores doses. A toxicidade pulmonar aguda foi avaliada pela análise de LDH e proteínas totais no fluido de lavagem bronco-alveolar (BALF) após a administração combinada das formulações 5FU-MS e 5FU-NS para administração como um sistema terapêutico único (5FU-MS/NS), e análise de dano tecidual pulmonar em ratos. Os resultados da análise bioquímica e histológica indicaram o baixo potencial de indução de lesão tecidual a partir da administração pulmonar combinada das formulações, em relação ao fármaco livre. A análise do perfil farmacocinético por microdiálise pulmonar evidenciou o êxito no desenvolvimento dos sistemas carreadores, tornando possível duplicar o t1/2 do 5FU e aumentar significativamente a biodisponibilidade no tecido pulmonar. Os resultados obtidos indicam a eficiência das formulações 5FU-MS e 5FU-NS em alcançar os benefícios terapêuticos do fármaco 5FU com menores doses e maiores intervalos de administração. Este trabalho de tese apresenta uma abordagem promissora na terapia de neoplasias com recorrência de metástase pulmonar.The absence of a single therapeutic agent suitable for the treatment of metastatic melanoma and the potential of 5FU chemotherapy (5-fluorouracil) motivated this study, which aimed the development of carrier systems based on micro-/ and nanostructures containing 5FU to increase the therapeutic efficacy and reduce toxicity of this drug by pulmonary administration. Two different formulations of dry powders were developed with natural polymers, chondroitin sulfate and hydroxypropyl-methyl-cellulose, denomined 5FU-MS and 5FU-NS, using the spray-drying and vibrational piezoelectric atomization techniques, respectively. Both formulations were evaluated in terms of physico-chemical characteristics, in vivo toxicological behaviors (C. elegans and in Wistar rats), bioavailability and penetration in the lung tissue by quantifying of drug free fraction by lung microdialysis. The physicochemical analysis showed that were obtained as micrometric (5FU-MS) and submicron particles (5FU-NS), with average diameters of particle 2.546 ± 0.07 m and 0.652 ± 0.03 m, and respirable fraction (FR%) of 55.12 ± 2.98 and 76.84 ± 0.07, respectively. Both showed suitable characteristics and properties for pulmonary delivery, with deposition capacity in the middle and deep lung portions. The toxicity of the formulations evaluated in C. elegans considered the death rate, body development, DL50 and production of ROS to nematodes under acute and chronic treatment. The results showed significant reduction of toxicity, reducing the death rate and greater development of the groups treated with 5FU-MS and 5FU-NS formulations compared to the free drug, suggesting satisfactory safety profile for administration. In addition, 5FU-MS proved to be a pro-oxidant agent, representing a promising differential of this system which can achieve greater sensitization of tumoral cells with lower doses. Acute pulmonary toxicity was evaluated by analyzing LDH, and total protein in the bronchoalveolar lavage fluid (BALF) after combined administration of 5FU-MS formulations and 5FU-NS for administration as a single therapeutic system (5FU-MS/NS) and analysis of lung tissue damage in rats. The results of biochemical and histological analysis indicated the low potential to induce tissue damage from the pulmonary administration of combined formulations, compared to free drug. Analysis of the pharmacokinetic profile for pulmonary microdialysis showed the successful development of carrier systems, making it possible to double the t1/2 of 5FU and significantly increase bioavailability in lung tissue. The results indicate the effectiveness of the formulations 5FU-MS and 5FU-NS in achieving the therapeutic benefits of the drug 5FU at lower doses and higher dosing intervals. This thesis work presents a promising approach to cancer therapy with lung metastasis recurrence.
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Ben, slimen Fedia. "Caractérisation des verres luminescents préparés par la méthode sol-gel." Thesis, Angers, 2016. http://www.theses.fr/2016ANGE0019/document.
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Les verres dopés par des ions de terres rares ou/et des nanoparticules de semi-conducteurs continue à faire l’objet de plusieurs recherches grâce à leur efficacité dans les domaines d’optoélectroniques. En effet, ces matériaux sont parmi les candidats potentiels pour des applications en photonique tels que les amplificateurs à fibre optique, les convertisseurs de lumière, les capteurs et les guides d'ondes 3D.Dans le cadre de cette thèse, des verres à base de silice (SiO2)dopé par des ions d’europium (Eu3+) ont été préparés par le processus sol-gel. Afin de mieux disperser les ions de terres rares et d’améliorer leur émission, les verres ont été codopés par le phosphore et/ou l’aluminium. Des nanoparticules de semi-conducteur (CdS) ont été aussi introduite dans le verre afin d’augmenter l’absorbance de la lumière excitatrice et d’obtenir une émission plus intense des ions Eu3+. Les verres préparés ont été analysés par photoluminescence et par la technique de rétrécissement des raies de luminescence (FLN). Ces mesures ont été suivi par des simulations par la méthode de dynamique moléculaire (DM)afin d’étudier l’effet de phosphore et/ou de l’aluminium sur l’environnement local des ions d’europium et la dispersion de ces ions dans la matrice vitreuse. La présence de deux types de sites des ions d’europium dans le verre de silicophosphates a été mise en évidence et a été confirmé par les deux techniques (FLN et DM). L’effet des nanoparticules de CdS sur l'émission des ions Eu3+dans un verre de silicophosphate a été aussi étudié et il a été montré que l’émission des ions Eu3+ est considérablement dépendante de la concentration des nanoparticules de CdS et de la température de recuitGlasses doped with rare earth ions and/or semiconductor nanoparticles continues to be the subject of several studies due to their effectiveness in optoelectronic fields. Indeed, these materials are among the potential candidates for photonic applications such as optical fiber amplifiers, light converters, sensors and 3D waveguides. As part of this thesis, silica-based glasses (SiO2) doped with europium ions (Eu3+) were prepared by the sol-gel process. In order to better disperse the rare earth ions and improve their emission, the glasses were codoped with phosphorus and/or aluminum. Semiconductor nanoparticles (CdS) were also introduced into the glass in order to increase the absorbance of the excitation light and to obtain a more intense emission of Eu3+ ions. The prepared glasses were analyzed by photoluminescence and by the technique of Fluorescence line narrowing (FLN). These experimental measurements were followed by theoretical simulations using the molecular dynamics method (DM) to study the effect of phosphorus and/or aluminum on the local environment of the europium ions and their dispersion in the vitreous matrix. The presence of two types of europium ion sites in the glass silicophosphates has been demonstrated and confirmed by two techniques (FLN and DM). The effect of CdS nanoparticles on the emission of Eu3+ ions in a glass silicophosphate was also studied and it was shown that the emission of Eu3+ ions is considerably dependent on theconcentration of CdS nanoparticles and annealing temperature
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Ligmajer, Filip. "Pokročilé plazmonické materiály pro metapovrchy a fotochemii." Doctoral thesis, Vysoké učení technické v Brně. CEITEC VUT, 2018. http://www.nusl.cz/ntk/nusl-387738.
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Plazmonika, tedy vědní obor zabývající se interakcí světla s kovovými materiály, nabízí ve spojení s nanotechnologiemi nezvyklé možnosti, jak světlo ovládat a využívat. Výsledkem tohoto spojení může být například zaostřování světla pod difrakční limit, zesilování emise nebo absorbce kvantových zářičů, či extrémně citlivá detekce molekul. Tato práce se zabývá zejména možnostmi využití plazmoniky pro vývoj plošných optických prvků, tzv. metapovrchů, a pro fotokatalytické aplikace založené na plazmonicky generovaných elektronech s vysokou energií, tzv. horkých elektronech. Nejprve jsou vysvětleny teoretické základy plazmoniky a je poskytnut přehled jejích nejvýznamnějších aplikací. Poté jsou představeny tři studie zabývající se využitím plazmonických nanostruktur pro ovládání fáze a polarizace světla, pro vytváření dynamicky laditelných metapovrchů, a pro foto-elektrochemii s horkými elektrony. Společným prvkem těchto studií je pak používání pokročilých, resp. v rámci těchto oblastí netradičních, materiálů, jako např. oxidu vanadičitého nebo dichalkogenidů přechodných kovů.
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Chavillon, Benoit. "Synthèse et caractérisation d'oxydes transparents conducteurs de type p pour application en cellules solaires à colorant." Phd thesis, Université de Nantes, 2011. http://tel.archives-ouvertes.fr/tel-00674543.
Full textAbstract:
La thèse avait pour objectif la préparation de semi-conducteurs de type p sous forme de nanoparticules pour la réalisation de cellules à colorant fonctionnant sur le principe inverse aux cellules dites de Grätzel, à savoir par photoinjection de trou d'un colorant à une cathode. Dans ce cadre, nos études ont porté en premier lieu sur la réalisation de films homogènes et d'épaisseur ajustable de NiO par voie hydrothermale. Ces films ont été caractérisés. Ils mettent en exergue de façon systématique la présence d'une portion infime de nickel métallique qui pourrait être à l'origine de l'excellent comportement de ce matériau en photocathode. Cependant, l'accession à de plus haut rendements photovoltaïques nécessite l'obtention d'autres semiconducteurs de type p. A cette fin, la synthèse de nanoparticules de CuGaO2 par voie hydrothermale avec de l'éthylène glycol comme agent réducteur a été entreprise. La réalisation de cellules à colorant à partir de ce matériau conduit à des caractéristiques photovoltaïques prometteuses qui restent à optimiser. Parallèlement, l'oxysulfure de lanthane et de cuivre, LaOCuS, reporté dans la littérature avec une forte mobilité de ses porteurs de charges positifs a pu être stabilisé sous la forme de nanoparticules par voie solvothermale dans l'éthylène diamine. Malheureusement, ce matériau n'a pu être testé pour l'application visée faute d'un médiateur redox adapté. Enfin, la stabilisation de ZnO:N de type p a pu être réalisée par nitruration réactive du dioxyde de zinc ZnO2. Le matériau final se caractérise par une structure de type wurtzite qui s'accommode de la présence de groupements peroxydes et d'anions nitrures ainsi que d'une non stoechiométrie en zinc.
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Larsson, Emanuel. "Evaluation of the Dual-Modal usage of contrast agents by means of Synchrotron X-ray Computed Microtomography and Magnetic Resonance Imaging using Macrophages loaded with Barium Sulfate and Gadolinium Nanoparticles for Detection and Monitoring in Animal Disease Models." Doctoral thesis, Linköpings universitet, Molekylär ytfysik och nanovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122607.
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¨This thesis focuses on evaluating the dual-modal Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) capabilities of contrast agents. For such purposes a gadolinium based contrast agent is of high interest, due to its paramagnetic properties, which while present inside a magnetic field will hence interact with the protons spins of water (in tissue and fat) and shorten their the T1 relaxation time, thereby creating a positive image contrast in MRI. Furthermore, the X-ray Mass Attenuation Coefficient (MAC) of gadolinium is relatively high, thus suggesting its potential use, also as a CT contrast agent. Gadolinium nanoparticles (GdNPs) can be loaded into cells, such as macrophages, which offers the possibility to track cells inside entire organisms. In the first step the uptake of GdNPs inside cells was investigated, together with a test for toxicity. To show the potential of using GdNP loaded macrophages for functional imaging of inflammation, an acute allergic airway inflammation mouse model (mimicking asthma in humans) was used and analyzed by in-situ synchrotron phase contrast CT. In the first step this approach was evaluated using macrophages loaded with a clinical contrast agent containing barium sulphate (BaSO4), since this agent is known to provide high contrast in CT. In the ultimate step a combination of both BaSO4 and GdNP loaded macrophages was used in the same asthmatic mouse model and analyzed by dual modal Synchrotron phase contrast CT and Micro Magnetic Resonance Imaging (μ-MRI). Complementary results in terms of the biodistribution of injected macrophages could only be obtained by the combination of both synchrotron phase contrast CT and μ-MRI, where the first modality allows a detailed localization of clustered BaSO4 loaded macrophages, but fails to detect single macrophages, which could instead be indirectly observed by μ-MRI as an increase of the T1-contrast, coming from the soft tissue of mice injected with GdNP loaded macrophages.
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La, Ly B. T. "From Gd2O3suspension to nanocomposite: Synthesis, properties and radiation protection." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/2019.
Full textAbstract:
This study provides details for the design, preparation of an environmentally friendly, clinically safe and lightweight radiation protective shield made ofGd2O3/epoxy nanocomposite (Gd-nanocomposite) which is proposed as an alternative to traditional toxic lead (Pb)-based aprons for diagnostic X-ray protection. In theory, this particulate nanocomposite can possess significant features of both inorganic particles and organic polymeric matrices. However, in practice, its performance does not simply depend on the sum of the individual contributions of characteristics of the constituent phases but on the interaction of their inner interfaces and the homogeneous dispersion of inorganic particles in the polymer matrix.
The miniaturization of inorganic particles to nanoscale before mixing with an organic matrix has been considered as an effective way to improve the interface of the dispersion phase. Unfortunately, homogeneous dispersion has still not yet been achieved in this type of material due to the coalescence of nanoparticles resulting from the large surface area of nanoparticles and their chemical incompatibility with the matrix. The effect of inter-particle forces arising from adsorbed typical cationic and anionic surfactants on the morphology of the ball milled gadolinium oxide (Gd2O3) is investigated to attain the optimal conditions for interface improvement between Gd2O3 particles and an epoxy matrix.
The experimental outcomes are interpreted in terms of the stabilization and interaction mechanisms of the fine washed Gd2O3 particles (size diameter
Based on the above outcomes, an optimal geometric design of a non-lead based X-ray protective material with lightweight per volume unit is prepared. A plateau with 28-30% increments in the value of fracture toughness (KIC (Mpa.m1/2)) is observed with a specific addition of 0.08 to 0.1 volume fraction (ϕs) of SDS-encapsulated Gd2O3 particles in pure epoxy. The same quantity of particles also optimally raises the critical strain energy release rate (GIC (J.m-2)) and Young’s modulus (E (MPa)) of epoxy by approximately 22-24% and 18-25% respectively. A 16 mm thick sheet of fabricated filled composite at ϕs of 0.08 and 0.1 can shield greater than 95% (0.5 mm Pb-equivalence) and 99% (1 mm Pb-equivalence) respectively of a primary X-ray beam in the range of 60-120kVp. At the same X-ray attenuation (99% attenuation), the specimen is 7, 8.5, and 16 times lighter than wood, glass, and concrete respectively. At 0.5 mm Pb-equivalence, the composite also has 4.5-19.4% less weight per unit area than current commercial non-lead products.
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El, Zein Basma. "Growth and characterization of zinc oxide (ZnO) nanostructures for photovotaic applications." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10141/document.
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Le développement des nanotechnologies offre de nouvelles perspectives pour la conception des cellules solaire à fort rendement de conversion. Jusqu’à présent les efforts se sont portés principalement sur des structures à base de semi-conducteurs, de métaux et de polymères. Dans nos travaux, nous avons considéré des nanoparticules de Sulfure de Plomb (PbS) pour lesquelles l'énergie de bande interdite et les propriétés optiques sont fonction de la taille de la particule afin de tirer parti de l'ensemble du spectre optique couvert par l'énergie solaire. Nous avons également considéré des nanofils d'oxyde de zinc (ZnO) pour la séparation et le transport des charges photo-crées. Nous pensons que l'association des nanoparticules de PbS avec des nanofils de ZnO devrait pouvoir augmenter considérablement le rendement des cellules solaires. Dans ce but, nous avons démontré la croissance auto-ordonné des nanofils de ZnO sur substrats silicium et verre par dépôt laser pulsé (pulsed laser deposition ) utilisant le réseau de nanoparois de ZnO en forme de nid d'abeille comme couche germe. Nous avons démontré que les conditions de croissance sont essentielles pour contrôler la cristallinité, la morphologie des nanofils de ZnO , ainsi que la densité de défauts de croissance. Les analyses MEB, DRX, TEM, et HR-TEM montrent que nous avons obtenu des nanostructures très cristallines et orientées verticalement. Nous avons également démontré la croissance in-situ de nanoparticules de PbS sans ligand sur la surface des nanofils de ZnO verticaux à l'aide de la technique SILAR (Successive Ionic Layer Adsoprtion and Reaction) .Nous avons constaté que les nanoparticules de PbS sont fortement accrochées à la surface des nanofils de ZnO avec différentes dimensions et des densités variables .Ces résultats ont été obtenus sans introduire de matière organique (Ligand) qui pourrait perturber à la fois la structure électronique à l'interface ZnO/PbS et le transfert des électrons du PbS au ZnO. Les analyses MEB, TEM et HR-TEM confirment le bon accrochage des nanoparticules de PbS sur les nanofils de ZnO . Leur forme est sphérique et elles sont poly-cristallines. A la fin de ce travail de thèse nous proposons une hétérojonction p-PbS/n-ZnO constituée de nanoparticules de PbS dopées P et de nanofils de ZnO dopés n pour de futures applications en photovoltaïqueTo date, the development of nanotechnology has launched new ways to design efficient solar cells. Strategies have been employed to develop nanostructure architectures of semiconductors, metals, and polymers for solar cells. In this research we have considered the Lead sulfide (PbS) nanoparticles with their tunable band gap and optical properties to harvest the entire solar spectrum which can improve the optical absorption, and charge generation. On the other hand, Zinc oxide (ZnO) nanowires will provide the charge separation and transportation. The ZnO Nanowires sensitized with PbS nanoparticles might significantly impact power conversion efficiency of the solar cells Driven by these unique properties, we demonstrate the successful growth of self catalyzed ZnO nanowires on silicon and glass substrates, by pulsed laser deposition (PLD) using ZnO nanowall network with honeycomb structure as seed layer. We identified that the growth parameters are vital to control the crystallinity, morphology and the defect levels in the synthesized ZnO nanowires. SEM, XRD, TEM, HRTEM analysis show that the nanostructures are highly crystalline and are vertically oriented. We also report the in-situ growth of PbS nanoparticles without linker on the surface of well –oriented ZnO NWs by (SILAR) technique. The PbS Nanoparticles are packed tightly on the surface of the ZnO Nanowires with different sizes and densities, without insulating nature organic ligands, which might affect both the electronic structure at the interface and the electron - transfer rate. The SEM, TEM, HRTEM, PL and XRD analysis, confirm the attachment of the spherical shape polycrystalline PbS nanoparticles. We propose at the end of the thesis the p-PbS /n-ZnO hetero-junction with its future applications in solar cells
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Corkery, Robert, and robert corkery@anu edu au. "Artificial biomineralisation and metallic soaps." The Australian National University. Research School of Physical Sciences and Engineering, 1998. http://thesis.anu.edu.au./public/adt-ANU20080124.190014.
Full textAbstract:
In this thesis, geometry is used as a basis for conducting experiments aimed at growing
and arranging inorganic minerals on curved interfaces. Mineralisation is directed using
crystalline and liquid-crystalline metallic soaps and surfactant/water systems as
templates.¶
A review of the history, syntheses, structure and liquid crystallinity of metallic soaps
and other amphiphiles is presented as a foundation to understanding the interfacial
architectures in mesostructured template systems in general.¶
In this study, a range of metallic soaps of varying chain length and cation type are
synthesised and characterised to find potentially useful templates for mineral growth.
These include alkaline-earth, transition metal, heavy metal and lanthanide soaps. These
are systematically characterised using a variety of analytical techniques, including
chemical analyses, x-ray diffraction (XRD) infrared spectroscopy (IR) and differential
scanning calorimetry (DSC). Their molecular and crystal structures are studied using
transmission electron microscopy (TEM), cryo-TEM, electron diffraction (ED), electron
paramagnetic spin resonance (EPR), absorption spectroscopy (UV-VIS), high resolution
laser spectroscopy, atomic force microscopy (AFM), nuclear magnetic resonance
spectroscopy, scanning electron microscopy (SEM), electron dispersive x-ray analysis
(EDXA), thermal gravimetric analysis (TGA) and magnetic measurements. Models for
the molecular and crystal structures of metallic soaps are proposed. The soaps are
predominantly lamellar crystalline or liquid crystalline lamellar rotor phases with tilted
and/or untilted molecular constituents. These display evidence of varying degrees of
headgroup organisation, including superstructuring and polymerisation. A single crystal
structure is presented for a complex of pyridine with cobalt soap. Simple models for
their structure are discussed in terms of their swelling properties in water and oils.
Experiments are also presented to demonstrate the sorbent properties of aluminium
soaps on oil spills.¶
The thermotropic liquid crystallinity of alkaline earth, transition metal, heavy metal and
lanthanide soaps is investigated in detail. This is done to assess their suitability as
templates, and to document their novel thermotropic behaviour, particularly the
relatively unknown lanthanide soaps. Liquid crystalline behaviours are studied using
high-temperature XRD (HTXRD), hot-stage optical microscopy and DSC. Models for a
liquid crystalline phase progression from crystals to anisotropic liquids are discussed in
terms of theories of self-assembly and interfacial curvature. The terminology required
for this is drawn from various nomenclature systems for amphiphilic crystals and liquid
crystals. General agreement with previous studies is reported for known soaps, while
liquid crystallinity is demonstrated in the lanthanide and some non-lanthanide soaps for
the first time. A general phase progression of crystalline lamellar through liquid
crystalline lamellar to non-lamellar liquid crystalline is discussed in terms of models
concerned with the molecular and crystal structures of the soaps and their phase
transitions via headgroup and chain re-arrangements.¶
Experiments aimed at guiding growth of metal sulfides using metallic soaps as
templates are described, and a model for this growth is discussed. Metal sulfides have
been successfully grown by reacting crystalline and liquid crystalline transition metal
and heavy metal soaps with H2S gas at room temperature and at elevated temperature.
These have been characterised using XRD, TEM, ED and IR. Sulfide growth is
demonstrated to be restricted and guided by the reacting soap template architecture.
Zinc, cadmium, indium and lead soaps formed confined nanoparticles within the matrix
of their reacting soap template. In contrast, curved and flat sheet-like structures, some
resembling sponges were found in the products of sulfided iron, cobalt, nickel, copper,
tin and bismuth soaps. A model to explain this behaviour is developed in terms of the
crystal and liquid crystal structures of the soaps and the crystal structures of the metal
sulfide particles.¶
Liquid crystalline iron soaps have been subjected to controlled thermal degradation
yielding magnetic iron oxide nanoparticles. Some XRD and TEM evidence has been
found for formation of magnetic mesostructures in heat-treated iron soaps. Models for
the molecular and liquid crystalline structure of iron soaps, their thermotropic phase
progression and eventual conversion to these magnetic products are discussed.
Systematic syntheses of mesoporous silicates from sheeted clays are discussed.¶The
templates that have been used are cationic surfactants and small, organic molecular
salts. Experiments are reported where a cooperative self-assembly of
surfactant/water/kanemite plus or minus salt and oils yields 'folded sheet materials'
(FSM'S). Templating of kanemite has also been achieved using cobalt cage surfactants.
A theoretical prediction of the specific surface areas and specific volumes of
homologous sets of FSM's gave excellent agreement with measured values. The
geometry and topology of the mesostructures are discussed. A theoretical model is also
discussed regarding the curvature found in the sheets of natural clays , and results of
templating clays and silica using metallic soaps are presented. Experiments and a model for low temperature nucleation and growth of microporous silicalite-1 are described in
terms of silica templating by water clathrates.¶
Finally, the problem of finding minimal surface descriptions of crystal networks is
addressed. Combinatoric methods are used to disprove the existence of possible
embeddings of type I and II clathrate networks in non-self intersecting periodic minimal
surfaces. The crystal network of the clathrate silicate, melanophlogite is successfully
embedded in the WI-10 self-intersecting surface. Details of a previously unreported,
genus-25 periodic surface with symmetry Im3m are discussed.