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1
Scholz, Timothy Theodore. "Electron scattering by atomic hydrogen." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335441.
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Walker, Richard John. "Behaviour of nanocolloidal particles on mica : investigations using atomic force microscopy." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4633.
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In this thesis we used atomic force microscopy (AFM) to investigate systematically the behaviour of both electrostatically stabilised silica and sterically stabilised polystyrene (PS) colloidal systems on freshly cleaved mica substrates. For the silica colloidal nanoparticles we explored the effect of colloidal suspension concentration, particle size, and different application techniques on both the adsorption behaviour and subsequent structuring of the particles. For the PS colloidal nanoparticles we explored concentration effects and experimented with both dip-coating and droplet application techniques. We showed that silica nanoparticles adsorbed onto mica via irreversible adsorption that possessed lateral mobility due to the weak attraction between the nanoparticles and the substrate, facilitating subsequent capillary structuring of the nanoparticles during drying. We associated the effects of volume fraction with Debye screening, and kinetics effects with particle size and volume fraction. We also successfully imaged a partially dried film and showed the role of convective/capillary forces in the structuring of the nanoparticles. Studies with variations in particle size generated a number of different topography structures; with dewetting phenomena observed for 10 nm nanoparticles and the formation of crystalline structures for 100 nm nanoparticles. Spin coating techniques were used to produce even larger crystalline structures of nanoparticles. Size dependent ordering occurred for low concentration samples due to the polydispersity of the colloidal suspension. We showed that acceleration can affect interparticle spacing. We also studied the role of rotational speed on the crystallinity of the particle configurations and showed how fine tuning of rotational speed can generate large scale monolayer crystalline formations of nanoparticles.
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LAU, JOAN M. "IMAGING MEMBRANE PROTEINS USING ATOMIC FORCE MICROSCOPY TECHNIQUES." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022192720.
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Clark, Eugene Laurence. "Measurements of energetic particles from ultraintense laser plasma interactions." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271738.
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Maynard, Andrew David. "The collection and analytical electron microscopy of ultrafine aerosol particles." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281951.
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VanMetre, Holly Sue Morris. "Individual submicrometer particles and biomolecular systems studied on the nanoscale." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3207.
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The necessity to explore nanoscopic systems is ever increasing in the world of science and technology. This evolving need to study such physically small systems demands new experimental techniques and methodologies. Atomic force microscopy (AFM) is a versatile technique that can overcome many nanoscopic size limitations. AFM has been utilized in the world of nanotechnology to study physiochemical properties of particles, materials, and biomolecules through characterization of morphology, electrical and mechanical properties, binding interactions, and surface tension, among others. The work discussed herein is largely a report of several novel AFM methodologies that were developed to allow new characterization techniques of individual submicrometer particles and single biomolecular interactions.
The effects of atmospheric aerosols on the radiative budget of the earth and climate are largely unknown. For this reason, characterizing the physiochemical properties of aerosols is vital. Since the particles that have relatively long lifetimes in the atmosphere are smaller than one micrometer in size, high resolution microscopy techniques are required to study them. AFM is a suitable technique for single particle studies because it has nanometer spatial resolution, can perform experiments under ambient pressure and variable relative humidity and temperature. These advantages were utilized here and AFM was used to study morphology, organic volume fraction, water uptake, and surface tension of nascent sea spray aerosol (SSA) particles as well as laboratory generated aerosols composed of relevant chemical model systems. The morphology of SSA was found, often times, to be composed of core-shell structure. With complementary microscopy techniques, the composition of the core and the shell was found to be inorganic and organic in nature, respectively. Novel methodology to measure water uptake and surface tension of single substrate deposited particles with AFM was established using chemical model systems. Furthermore, these methodologies were employed on nascent chemically complex SSA particles collected from a biologically active oceanic waveflume experiment. Finally, phase imaging was used to measure organic volume fraction on a single particle basis and was correlated with biological activity. Overall, this suite of single (submicrometer) particle AFM analysis techniques have been established, allowing future systematic studies of increasing complexity aimed at bridging the gap between the simplicity of laboratory generated particles and the complexity of nature.
Another nanotechnology topic of interest is studying single biomolecular interactions. Virtually every biological process involves some amount of minute forces that are required for the biomolecular system to function properly. For example, there are picoNewton forces associated with enzymatic motions that are important for enzyme catalysis. The AFM studies reported here use a model enzyme/drug system to measure the forces associated with single molecule adhesion events. Escherichia Dihydrofolate Reductase (DHFR) is a target of cancer therapeutic studies because it can be inhibited by drugs like methotrexate (MTX) that are structurally similar to the natural folate binder but have much higher binding affinity. One of the obstacles of single molecular recognition force spectroscopy (MRFS) studies is the contribution of non-specific forces that create a source of uncertainty. In this study, DHFR and MTX are bound to the surface and the AFM tip, respectively, using several different linking molecules. These linking molecules included polyethylene glycol (PEG) and double stranded DNA (dsDNA) and the distribution of forces was compared to scenarios were a linker was not employed. We discovered that dsDNA and PEG both allow identification and removal of non-specific interaction forces from specific forces of interest, which increases the accuracy of the measurement compared to directly bound constructs. Traditionally, the linker of choice in the MRFS community is PEG. Here, we introduce dsDNA as a viable linker that offers more rigidity than PEG, which may be desirable in future molecular constructs.
The majority of the work and data presented in this dissertation supports the establishment of new AFM methodologies that can be used to better explore single biomolecular interactions and individual submicrometer particles on the nanoscale.
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Wang, Yan. "Measurement of the interactions between colloidal particles and fibres using atomic force microscopy." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405409.
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Anderson, Virginia Rose. "Atomic Layer Deposition of Platinum Particles, Titanium Oxide Films, and Alkoxysilane Surface Layers." Thesis, University of Colorado at Boulder, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3621292.
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<p> Atomic Layer Deposition (ALD) is a an excellent technique for depositing conformal thin films on complex geometries in layer by layer fashion. The mechanisms of depositing TiO<sub>2</sub>, platinum, and ethoxysilane molecules were probed with <i>in situ</i> Fourier transform infrared (FTIR) in order to better understand and improve the process. Each of these studies involves TiO<sub>2</sub>. </p><p> There are many uses for thin films of titanium dioxide, a semiconductor and high dielectric material. Current Atomic Layer Deposition (ALD) of TiO<sub> 2</sub> generally involves water or ozone, which can oxidize and corrode some substrates of interest. Ritala et al. successfully deposited an assortment of metal oxides using no water, but instead, metal alkoxides and metal halides as precursors. Presented is a study of ALD of titanium dioxide using titanium tetrachloride (TiCl<sub>4</sub>) and titanium tetraisopropoxide (TTIP). In situ Fourier transform infrared (FTIR) studies revealed that the mechanism for TiO<sub>2</sub> ALD using titanium tetrachloride and titanium tetraisopropoxide changed with temperature. At temperatures between 250 and 300°, the isopropoxide species after TTIP exposures quickly underwent β-hydride elimination to produce TiOH species on the surface. The observation of propene by quadrupole mass spectrometry supported the β-hydride elimination reaction pathway. Deposition was investigated between 150 and 300° on substrates including zirconia, alumina, and silica. Quartz crystal microbalance results and X-ray reflectivity showed that the system grew 0.5–0.6 Å/cycle at 250° X-Ray photoelectron studies also confirmed TiO<sub>2</sub> film growth. </p><p> In another aspect of ALD use, self-limiting chemistry assisted with terminating a surface with alkoxysilanes. Tire rubber contains additives such as carbon black or silica particles to provide strength. Although in theory Kevlar fibers would provide strength while lowering the density and increasing car fuel efficiency, in practice Kevlar fibers disperse only very poorly in the rubber, leading to inhomogeneity. In order the increase the mixing likelihood between rubber and Kevlar, the reactions of some sulfurous siloxanes were examined on both aluminum oxide and titanium oxide. The titanium oxide adhesion layer allowed the deposition of molecules on the surface that looked promising for improving mixing with rubber and decreasing the weight of tires. </p><p> Atomic layer deposition offers the possibility of more precision in platinum deposition. In a platinum deposition study, the nucleation and growth of non-conformal platinum on TiO<sub>2</sub> and WO<sub>x</sub> powder using Pt(hfac)<sub> 2</sub> and formalin was examined with in-situ FTIR and transmission electron microscopy (TEM). Interest in substitution of Pt/C as the oxidation reduction reaction catalyst in polymer electrolyte membrane fuel cells (PEMFCs) led to the ALD synthesis of Pt/WO<sub>x</sub> and Pt/TiO<sub>2</sub>. A nucleation period on the order of 100 cycles was observed, after which, platinum loading and particle size measurably increased with increasing cycle number. The adsorption of the hfac ligand on the metal oxide substrate effectively inhibits nanoparticle coalescence during the growth phase, which led to further investigation of its use as a site-blocking agent. The results showed that Pt particle distance could be increased with the use of hfacH.</p>
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King, David Michael. "The optical properties of nanoscale coatings on particles fabricated by atomic layer deposition." Connect to online resource, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3337114.
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Geiger, Daniel [Verfasser]. "Particles on surfaces: development and application of Atomic Force Microscopy methods to study time dependent adhesion of nano particles / Daniel Geiger." Ulm : Universität Ulm, 2018. http://d-nb.info/116253995X/34.
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Linardos, S. "Preparation of submicron PZT particles with the sol-gel technique and direct measurement of inter-particles forces with atomic force microscope." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427149.
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Jedrzejczak, Maria. "Atomic spectrometry of particles evaporating in the inductively coupled plasma : pure and applied aspects." Thesis, Birkbeck (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248219.
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Lokar, William Joseph. "Surfactant Adsorption during Collisions of Colloidal Particles: A Study with Atomic Force Microscopy (AFM)." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/28369.
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The adsorption of cationic and zwitterionic surfactants is studied in aqueous electrolyte solutions. A Maxwell relation is applied to Atomic Force Microscopy (AFM) data to obtain changes in surfactant adsorption as a function of the separation between two glass surfaces. In addition, self-consistent field theory (SCF) is used to calculate the adsorption profiles and interaction energies when two solid surfaces are brought into close proximity. Addition of surfactant is shown to affect the surface forces when lateral surfactant chain interactions are significant. The surfactant adsorbs and desorbs in response to over-lapping electric double-layers, with the adsorption being affected at larger solid-solid separations when the double-layer force is longer ranged. Furthermore, elimination off the surface charge or net surfactant charge eliminates adsorption with decreased solid-solid separation. The magnitude of the changes in surfactant adsorption at decreased separations is shown to scale with the chain length of the surfactant. Surfactant adsorption exceeds that required to regulate the surface charge according to the constant potential boundary condition in Poisson-Boltzmann theory. An equation of state including short-ranged (contact) tail interactions is proposed to describe both the adsorption of surfactant and the surface forces at small separations, where the double-layers overlap. Furthermore, SCF calculations show confinement-induced phase transitions when the surfactant layers on opposite surfaces merge. These phase transitions lead to further surfactant adsorption and a corresponding attractive force.<br>Ph. D.
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Matula, Oliver [Verfasser], and Andrey [Akademischer Betreuer] Surzhykov. "Atomic Processes with Twisted Particles: Photoionization and Radiative Recombination / Oliver Matula ; Betreuer: Andrey Surzhykov." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1179924983/34.
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Zhang, Hua, and 张华. "Characterization of signal-production processes of single particles inICP by time-resolved ICP-AES." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47150567.
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The research in this thesis aims to characterize the signal-production processes of single particles in the ICP using time-resolved ICP-AES. Signal-production processes, including desolvation, vaporization, atomization, ionization, and diffusion, determine the temporal emission intensity of a single particle. Bimetallic nanoparticles of BaTiO3 (average diameter = 115 nm) were used as test particles. The particles were introduced into the ICP by nebulization of the suspension of the particles in water. As the ion plume of a particle moves up in central channel of the ICP, a temporal emission peak of the analyte atoms in the plume is produced. The emission intensity at any point of time in the temporal profile is related to the degree of vaporization and excitation of the particle at the corresponding vertical position of the ICP. The signal-production processes can, in principle, be studied by measuring the temporal emission profiles. However, the emission intensity of single particles is typically low. Continuous integration of the entire ICP central channel further reduces the signal-to-background ratio (SBR).
A novel double-slit method has been developed to measure the temporal emission intensity of a single particle at two pre-defined ICP vertical positions. Two horizontal slits of slit height of 1 mm were placed in front of the monochromator. As the ion plume passes through the double-slit, two peaks in the temporal emission profile are produced. The configuration of the double-slit (slit height and distance between the two slits) was optimized for maximum signal-to-noise ratio (SNR) and temporal resolution of the double-peaks.
Fast data sampling rate (50,000 Hz) was used in proper sampling of the temporal emission peaks. Large data sets were obtained. Custom programs were developed to extract the relatively weak double-peaks from the temporal emission profiles. The data treatment strategy includes smoothing of the temporal profile to increase SNR and automated peak extraction based on the characteristics of the double-peaks (peak height, peak width, time-difference of the peak pair, and SNR). Four smoothing methods, including Moving Average Filtering, Savitzky-Golay Filtering, Fast Fourier Transform (FFT) and Wavelet Transform, were tested. FFT was adopted because the method requires only one parameter (the cutoff frequency) and is relatively easy to optimize.
Hundreds of double-peaks were obtained in a typical temporal profile of time duration of approximately 120 s. The emission intensity and peak width of the peak pair are correlated to determine the degree of vaporization of the analyte atoms, the extent of diffusion of the analyte atoms and the plume size, and the velocity of the plume in the ICP. Two types of double-peaks are identified. The relative peak height and peak width of the double-peaks in each type are related to the degree of vaporization of the single particles. Simulation of the evaporation rate of water droplets that enclose the single BaTiO3 particles shows that the time required for complete evaporation of water is a major factor that determines the degree of vaporization of BaTiO3 particles at the double-slit. Aggregation of BaTiO3 particles in the suspension was also investigated.<br>published_or_final_version<br>Chemistry<br>Master<br>Master of Philosophy
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Arai, Nozomi. "Self-Assembly of Colloidal Particles with Controlled Interaction Forces." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263693.
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Murray, Benjamin John. "The uptake of atomic oxygen and iron on ice : impact of ice particles on mesospheric chemistry." Thesis, University of East Anglia, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396668.
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Moisan, Christian. "Neutral pion production in the reactions 160+27Al, 58Ni, 208Pb at 95 MeVu." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59518.
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The inclusive production of neutral pions has been measured in reactions of 95 MeV/nucleon $ sp{16}$O+$ sp{27}$Al, $ sp{58}$Ni, $ sp{208}$Pb, using a setup of 8 lead-glass Cherenkov counter telescopes to detect in coincidence the two photons resulting from pion decays. The differential distributions of interest: d$ sigma$/dT$ sb{ pi}$, d$ sigma$/d$ Omega$, d$ sigma$/dy and d$ sigma$/dp$ sb{ rm t}$ are obtained from the experimental invariant cross section of the pions. The transverse momentum, kinetic energy, and angular distributions, are discussed in the framework of the moving thermal source model. The shape of d$ sigma$/dp$ sb{ rm t}$ and d$ sigma$/dT$ sb{ pi}$ is reproduced by a single source having a temperature close to 20 MeV and moving with a velocity between that of the nucleus-nucleus and the nucleon-nucleon center of mass rest frames. Relevant signatures of the energy and angular dependences of pion reabsorption have been extracted from the data. The deviations of the energy distributions from the thermal model predictions are consistent with the deduced behavior of reabsorption. It is also shown that the absorption can explain the evolution of the anisotropy of the angular distributions with the target mass.
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Beck, William A. "Semiclassical, Monte Carlo model of atomic collisions : stopping and capture of heavy charged particles and exotic atom formation /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9796.
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Blundell, Daniel Laurence. "The agglomeration of fine iron particles in a fluidised bed cascade." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060712.155401/index.html.
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Volkov, Mikhail. "Solving the quantum scattering problem for systems of two and three charged particles." Doctoral thesis, Stockholms universitet, Fysikum, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54832.
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A rigorous formalism for solving the Coulomb scattering problem is presented in this thesis. The approach is based on splitting the interaction potential into a finite-range part and a long-range tail part. In this representation the scattering problem can be reformulated to one which is suitable for applying exterior complex scaling. The scaled problem has zero boundary conditions at infinity and can be implemented numerically for finding scattering amplitudes. The systems under consideration may consist of two or three charged particles. The technique presented in this thesis is first developed for the case of a two body single channel Coulomb scattering problem. The method is mathematically validated for the partial wave formulation of the scattering problem. Integral and local representations for the partial wave scattering amplitudes have been derived. The partial wave results are summed up to obtain the scattering amplitude for the three dimensional scattering problem. The approach is generalized to allow the two body multichannel scattering problem to be solved. The theoretical results are illustrated with numerical calculations for a number of models. Finally, the potential splitting technique is further developed and validated for the three body Coulomb scattering problem. It is shown that only a part of the total interaction potential should be split to obtain the inhomogeneous equation required such that the method of exterior complex scaling can be applied. The final six-dimensional equation is reduced to a system of three dimensional equations using the full angular momentum representation. Such a system can be numerically implemented using the existing full angular momentum complex exterior scaling code (FAMCES). The code has been updated to solve the three body scattering problem.<br>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.
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Fisher, Dave S. "Two-Photon Polarization Spectroscopy of Atomic Cesium Using Circularly Polarized Light." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1292444234.
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Owen, Justin. "Simulation of electron beam dyanmics in the 22 MeV accelerator for a coherent electron cooling proof of principle experiment." Thesis, State University of New York at Stony Brook, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553316.
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<p> Coherent electron cooling (CeC) offers a potential new method of cooling hadron beams in colliders such as the Relativistic Heavy Ion Collider (RHIC) or the future electron ion collider eRHIC. A 22 MeV linear accelerator is currently being built as part of a proof of principle experiment for CeC at Brookhaven National Laboratory (BNL). In this thesis we present a simulation of electron beam dynamics including space charge in the 22 MeV CeC proof of principle experiment using the program ASTRA (A Space charge TRacking Algorithm). </p>
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Shehu, Yusufu. "Search for the electroweak production of supersymmetric particles in three-lepton events at the ATLAS detector with focus on compressed mass spectra." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/67205/.
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This thesis presents a search for the electroweak production of supersymmetry using the dataset taken by the ATLAS detector at the Large Hadron Collider with √8 = 8 TeV during 2012. Events with three leptons are selected and required to satisfy additional kinematic criteria that define optimised signal regions. In these signal regions, Standard Model processes are discriminated against, whilst retaining a large fraction of events produced by specified compressed supersymmetry scenarios. Compressed refers to near massdegeneracy between the decaying gauginos and the final state gauginos. The expected number of Standard Model events are estimated using a combination of Monte Carlo and data-driven methods, where the predictions are tested against data in specifically designed validation regions. Exclusion limits are then set at 95% confidence level (CL) on via ℓ`L- and via WZ-decay scenarios for the decaying charginos and neutralinos. With the ℓ`L halfway between the decaying charginos and neutralinos and the final state neutralinos, there is a new sensitivity up to 250 GeV. In scenarios with large mass splitting, the decaying chargino and neutralino masses are excluded up to 740 GeV. Looking forward to the 13 TeV data-taking, a search for the electroweak production of supersymmetry with threelepton final states is presented, with a first look at an optimisation strategy to improve sensitivity to charginos and neutralinos.
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Nugroho, Robertus Wahyu Nayan. "Modification of polymeric particles via surface grafting for 3D scaffold design." Doctoral thesis, KTH, Polymerteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174295.
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Surface modification techniques have played important roles in various aspects of modern technology. They have been employed to improve substrates by altering surface physicochemical properties. An ideal surface modifying technique would be a method that is applicable to any kind of materials prepared from a wide range of polymers and that can occur under mild reaction conditions. The work in this thesis has utilized four main concepts: I) the development of a ‘grafting-from’ technique by covalently growing polymer grafts from particle surfaces, II) the presence of steric and electrosteric forces due to long-range repulsive interactions between particles, III) a combined surface grafting and layer-by-layer approach to create polyelectrolyte multilayers (PEMs) on particle surfaces to fabricate strong and functional materials, and IV) the roles of hydrophilic polymer grafts and substrate geometry on surface degradation. A non-destructive surface grafting technique was developed and applied to polylactide (PLA) particle surfaces. Their successful modification was verified by observed changes to the surface chemistry, morphology and topography of the particles. To quantify the aggregation behavior of grafted and non-grafted particles, force interaction measurements were performed using colloidal probe atomic force microscopy (AFM). Long-range repulsive interactions were observed when symmetric systems, i.e., hydrophilic polymer grafts on two interacting surfaces, and asymmetric system were applied. Electrosteric forces were observed when the symmetric substrates interacted at pH 7.4. When PEMs were alternately assembled on the surface of poly(L-lactide) (PLLA) particles, the grafted surfaces played a dominated role in altering the surface chemistry and morphology of the particles. Three-dimensional scaffolds of surface grafted particle coated with PEMs demonstrated high mechanical performance that agreed well with the mechanical performance of cancellous bone. Nanomaterials were used to functionalize the scaffolds and further influence their physicochemical properties. For example, when magnetic nanoparticles were used to functionalize the scaffolds, a high electrical conductivity was imparted, which is important for bone tissue regeneration. Furthermore, the stability of the surface grafted particles was evaluated in phosphate buffered saline (PBS) solution. The nature of the hydrophilic polymer grafts and the geometry of the PLLA substrates played central roles in altering the surface properties of films and particles. After 10 days of PBS immersion, larger alterations in the surface morphology were observed on the film compared with microparticles grafted with poly(acrylic acid) (PAA). In contrast to the PAA-grafted substrates, the morphology of poly(acrylamide) (PAAm)-grafted substrates was not affected by PBS immersion. Additionally, PAAm-grafted microparticulate substrates encountered surface degradation more rapidly than PAAm-grafted film substrates.<br><p>QC 20151002</p>
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Bowman, Sherrie S. "Atomic and Molecular Oxygen Kinetics Involved in Low Temperature Repetitively Pulsed Nonequilibrium Plasmas." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1370365358.
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Kalra, Rita Rani. "An Improved Antihydrogen Trap." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226066.
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The recent demonstration of trapped atomic antihydrogen for 15 to 1000 seconds is a milestone towards precise spectroscopy for tests of CPT invariance. The confinement of a total of 105±21 atoms in a quadrupole magnetic trap was made possible by several improved methods. Improved accumulation techniques give us the largest numbers of constituent particles yet: up to 10 million antiprotons and several billion positrons. A novel cooling protocol leads to 3.5 K antiprotons, the coldest ever observed. Characterizing and controlling the geometry and density of these confined antimatter plasmas allow for consistency in antihydrogen production. Continued use of these methods along with the larger trap depth of a unique second-generation magnet are expected to yield greater numbers of trapped antihydrogen. The new magnet generates both quadrupole and octupole trap geometries, which should make it possible to reduce charged particle loss and will prove useful for laser cooling and spectroscopy. The ultra-low inductances of the magnet have been shown to vastly reduce turn-off times, which will optimize single-atom detection. Finally, improved detector characterization already makes us sensitive to smaller numbers of trapped antihydrogen atoms than before.
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Langmack, Christian Bishop. "Universal Loss Processes in Bosonic Atoms with Positive Scattering Lengths." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385483878.
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Yilmaz, Umit Oktay. "The Polarization Properties Of The Final State Particles In The Rare Radiative B-meson Decay." Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606100/index.pdf.
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A general analysis of the photon and lepton polarizations in the rare Bs &<br>#8594<br>&<br>#61543<br>l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of "<br>photon polarization asymmetry"<br>and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs &<br>#8594<br>&<br>#61543<br>l+l- decay to the new Wilson coefficients are also investigated.
It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.
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Myklatun, Ahne. "Production and Application of Micronsized Polysaccharide Particles - Studying Perturbation of a Model Mucus Barrier with Total Internal Reflection Fluorescence (TIRF) Microscopy and Atomic Force Microscopy (AFM) Indentation." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13742.
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The overall aim of this project was to produce homogeneously sized polysaccharide microparticles and apply these and similar sized particles as probes for investigation of mucin layers as a model for a biological barrier. Small polysaccharide particles have many applications, e.g. within the medical field of drug delivery. In this study a microfluidic system was developed to produce alginate beads, which can be used in drug delivery systems. Different designs, continuous phases and concentrations were tested in order to find an optimal system. Beads in the size range of 10 µm were produced using a device with T-shaped design and three inlets. An electrostatic bead generator was also used to make alginate beads, however the beads produced were too large to be used in the experiments with the mucin layers.One of the many challenges when working with drug delivery systems is the mucus barrier protecting the epithelial cells. In this study a model mucus barrier was made by immobilizing mucins, the glycoprotein responsible for the physical properties of the barrier. A procedure for fluorescence labelling of polystyrene beads with quantum dots was developed, and penetration of these beads into the model barrier was measured with total internal reflection fluorescence (TIRF) microscopy. In TIRF the excitation field intensity decays exponentially, and the emitted fluorescence intensity from the beads gives an indication of the distance between the beads and the surface. Measurements performed on mucin layers of different concentrations indicate that mucin concentrations above 0,5 mg/ml will result in a layer too thick or too dense to give a intensity signal. At mucin concentration 0,05 mg/ml fluorescence was observable in TIRF, and it was clearly weaker than for the control with a bead directly on a glass surface. This indicates that the beads hover over the surface due to the mucin layers, and show that it is in principle possible to measure the penetration depth of beads into mucin layer using TIRF. To simulate the condition in the lungs of cystic fibrosis (CF) patients, the mucin layers were incubated with alginate. Measurements were performed to see how this affected the penetration of the beads into the layer. A weaker fluorescent signal was obtained for these samples in TIRF, which suggests that there has been interaction between mucin and alginate. It was in addition investigated how different concentrations of G-blocks in the solution affected the penetration into the mucin-alginate layer. These testes were carried out using both TIRF and atomic force microscopy (AFM) nanoindentation experiments. The TIRF measurements were inconclusive, while the nanoindentation experiments showed decreased interaction between mucin-alginate layer and a bead.
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Williams, Michael D. Jr. "Searching for Clean Observables in $B -> D* /tau- \bar{\nu}_{\tau}$ Decays." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5885.
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In this thesis, the clean angular observables in the $\bar{B} \to D^{*+} \ell^- \bar{\nu}_{\ell}$ angular distribution is studied. Similar angular observables are widely studied in $B \to K^* \mu^+ \mu^-$ decays. We believed that these angular observables may have different sensitivities to different new physics structures.
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Hashimoto, Kota. "Inverse analysis of the structures of the liquid molecules and colloidal particles near the solid-liquid interfaces: the relation between the number density distribution and the experimental force curve." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263678.
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Young, Paul Michael. "Characterisation of particle-particle interactions using the atomic force microscope." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250827.
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An investigation has been conducted into factors affecting the interparticulate cohesion profile of three micronised drugs, as a function of humidity. An atomic force microscope (AFM) colloid probe technique was correlated with physico-chemical properties and in-vitro performance. Briefly, micronised drug particles of salbutamol sulphate, triamcinolone acetonide (TAA) and disodium cromoglycate (DSCG) were mounted onto Vshaped tipless cantilevers using a developed micromanipulation technique. Interactions between the AFM ‘drug probes’ and a series of model drug surfaces were conducted at a 15,30, 45, 60 and 75% relative humidity using a custom built perfusion apparatus connected to the AFM. As expected, separation energy distributions for drug probe interactions were dependent on the surface rugosity of the drug model surfaces. Separation energy measurements conducted between drug probes and individual micronised drug particles (mounted in polymer resin) suggested large variations in separation energy. Further analysis of such data suggested a lognormal separation energy distribution, however, limitations in individual particle measurements (finite particle measurements per experiment) allowed restricted statistical analysis.
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El, Haber Manuella. "Rôle des surfactants sur la formation des nuages : impact de la composition des aérosols et tension de surface de particules individuelles d'aérosols atmosphériques." Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10243.
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Dans l’atmosphère terrestre, les aérosols jouent un rôle crucial dans la diffusion et l’absorption des rayonnements solaires, et en tant que noyaux de condensation dans la formation des nuages. La vapeur d’eau se condense progressivement sur les particules d’aérosols, pour former des gouttelettes de nuage. Ce phénomène est régi par l’équation de Köhler dont un paramètre essentiel est la tension de surface. Pendant longtemps, ce paramètre n’a pourtant pas été pris en compte dans les modèles atmosphériques : la valeur de la tension de surface des aérosols a été considérée égale à celle de l’eau (~72.5 mN/m). Cependant, au cours dernières années, suite à la mise en évidence de la présence de tensioactifs à des concentrations significatives dans les aérosols atmosphériques, un intérêt croissant s’est porté sur la détermination de la tension de surface des particules d’aérosols atmosphériques. Ainsi dans la cadre de ce travail, les effets de la présence de composants d’intérêt atmosphérique tels les acides organiques (acide oxalique et acide glutarique) et les sels inorganiques (NaCl et (NH4)2SO4) sur la tension de surface de solutions de tensioactifs amphiphiles (TritonX100, Brij35, SDS, CTAC) ont été étudiés. Des comportements fortement non idéaux ont été observés pour la plupart des mélanges étudiés avec des synergies détectées dans certains cas. Les principaux composants atmosphériques augmentaient l'efficacité des tensioactifs amphiphiles. En parallèle, une technique de détermination de la tension de surface de particules atmosphériques individuelles microniques et submicroniques a été développée. L’application de la méthode micro Wilhelmy dans un microscope à force atomique (AFM) en employant une pointe cylindrique, a permis de quantifier la tension de surface des gouttelettes condensées sur des particules atmosphériques sous humidité relative contrôlée. Cette méthode a été validée par des mesures de la tension de surface sur des liquides de références et appliquée par suite sur divers prélèvements atmosphériques. Les valeurs de tensions de surface déterminées dans les particules atmosphériques individuelles sont inférieures à la tension de surface de l’eau. D’autre part, ces études ont montré que la condensation de l’eau sur ces particules d’aérosol est corrélée avec la tension de surface, pour une humidité relative de 82 ± 2 %. Ainsi, ce travail a permis pour la première fois de mesurer directement la tension de surface des particules individuelles atmosphériques et d’élucider l’effet de la tension de surface sur la formation de nuage<br>In Earth's atmosphere, aerosols play a crucial role in the diffusion and absorption of solar radiation, and as condensation nuclei in cloud formation. Water vapor gradually condenses on aerosol particles to form cloud droplets. This phenomenon is governed by the Köhler equation, where surface tension is a key parameter. For a long time, this parameter was not taken into account in atmospheric models: the surface tension value of aerosols was considered equal to that of water (~72.5 mN/m). However, significant concentrations of surfactants in atmospheric aerosols have been identified in recent years. Based on those results, there has been an increasing interest for determining the surface tension of atmospheric aerosol particles. In this work, the effects of the presence of typical aerosol components e.g., organic acids (oxalic acid and glutaric acid) and inorganic salts (NaCl and (NH4)2SO4) on the surface tension of amphiphilic surfactant solutions (TritonX100, Brij35, SDS, CTAC) were studied. Strong non-ideal behaviors were observed in most of the studied mixtures with synergies detected in some cases. The main atmospheric components increased the efficiency of the amphiphilic surfactants. In parallel, a technique for determining the surface tension of individual micron and submicron atmospheric particles was developed. The application of the micro Wilhelmy method in an atomic force microscope (AFM) using a cylindrical tip, made it possible to quantify the surface tension of droplets condensed on atmospheric particles under controlled relative humidity. This method was validated by surface tension measurements on reference liquids and subsequently applied to various atmospheric samples. The surface tension values determined in individual atmospheric particles are lower than the surface tension of water. Furthermore, these studies showed that the condensation of water on these aerosol particles is correlated with the surface tension, for a relative humidity of 82 ± 2%. Within this work, the surface tension of individual atmospheric particles was directly measured for the first time. Moreover, the effect of surface tension on cloud formation has been elucidated
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Higgins, Katrina Bernadette. "Positron scattering by atomic hydrogen." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317443.
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Scielzo, Nicholas David. "Measurement of the beta-neutrino correlation in laser trapped {sup 21}Na." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/821455-YDxgQ2/native/.
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Thesis (Ph.D.); Submitted to Univ. of California, Berkeley, CA (US); 1 Jun 2003.<br>Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--54350" Scielzo, Nicholas David. USDOE Director. Office of Science. Nuclear Physics (US) 06/01/2003. Report is also available in paper and microfiche from NTIS.
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Chun, Ka-him, and 秦嘉謙. "Single-particle inductively coupled plasma atomic emission spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/209488.
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Transient emission of a particle in inductively coupled plasma-atomic emission spectrometry (ICP-AES) depends on the fundamental processes of aerosol desolvation, particle vaporization and atomization, ionization, excitation and diffusion of the analyte. Ideally, the rate of the above processes can be determined from the evolution of the transient emission as the ion plume moves along the central channel of the ICP. However, the dimension of the ion plume is significantly smaller than the central channel. The signal-to-background and signal-to-noise ratios suffer when the entire channel is imaged. Deconvolution of the temporal profile is required to determine the emission intensity of the ion plume versus observation height. Small aperture can be used to locate the vertical emission position accurately, but the evolution of the plume emission is lost.
In this study, a double-slit method has been developed to pin-point two vertical positions of an ion plume. An ion plume travelling along the ICP central channel produces two peaks in the temporal emission profile. The temporal evolution of emission intensity can be correlated to delineate the degree of particle vaporization at the two positions. The relative widths and separation of the two peaks in a double-peak can be used to determine the analyte diffusion rate and particle velocity in the ICP, respectively.
An unicellular green algae, chlorella vulgaris, was used as the test particles. The average Mg content of the algae is equivalent to MgO particles of diameter of 265nm. The strong ionic emission at wavelength of 279.55nm was monitored using a ¼ -m monochromator equipped with a PMT detector. Method of curve fitting was used to filter out the noise with minimum distortion of the peak shape for accurate determination of peak height and peak width. The merits of curve fitting versus methods of smoothing such as moving average and Savitzky-Golay filtering will be discussed.
All transient emissions from the algal cells were detected with sufficient signal-to-noise ratio using a single-slit setup with slit height of 1mm at observation height of 18 mm above the load coil and ICP forward power of 1400 W. However, using the double-slit setup, less than half of the expected double-peaks were observed. One of the peaks in the double-peak can be below the detection limit and the double-peak is lost.
An innovative development of this study is that the relative sensitivity corresponding to the 2 slits can be varied to enhance the intensity of the weaker emission peak. The peak with insufficient signal-to-noise ratio for detection can be enhanced to a level above the limit of detection. The number of observed double-peaks in increased and the observed particles are more representative of the population.
Two types of double-peaks are categorized according to the relative intensity of the first peak to the second peak. A computer model was used to estimate the intensity ratio of the two emission peaks at different observation position of the ICP. The experimental and theoretical ratios agree generally. The theoretical ratio also shows the bias in the population sampled by the double-slit setup.<br>published_or_final_version<br>Chemistry<br>Master<br>Master of Philosophy
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Preiss, Philipp Moritz. "Atomic Bose-Hubbard Systems With Single-Particle Control." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:26718727.
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Experiments with ultracold atoms in optical lattices provide outstanding opportunities to realize exotic quantum states due to a high degree of tunability and control. In this thesis, I present experiments that extend this control from global parameters to the level of individual particles.
Using a quantum gas microscope for 87Rb, we have developed a single-site addressing scheme based on digital amplitude holograms. The system self-corrects for aberrations in the imaging setup and creates arbitrary beam profiles. We are thus able to shape optical potentials on the scale of single lattice sites and control the dynamics of individual atoms.
We study the role of quantum statistics and interactions in the Bose-Hubbard model on the fundamental level of two particles. Bosonic quantum statistics are apparent in the Hong-Ou-Mandel interference of massive particles, which we observe in tailored double-well potentials. These underlying statistics, in combination with tunable repulsive interactions, dominate the dynamics in single- and two-particle quantum walks. We observe highly coherent position-space Bloch oscillations, bosonic bunching in Hanbury Brown-Twiss interference and the fermionization of strongly interacting bosons.
Many-body states of indistinguishable quantum particles are characterized by large-scale spatial entanglement, which is difficult to detect in itinerant systems. Here, we extend the concept of Hong-Ou-Mandel interference from individual particles to many-body states to directly quantify entanglement entropy. We perform collective measurements on two copies of a quantum state and detect entanglement entropy through many-body interference. We measure the second order Rényi entropy in small Bose-Hubbard systems and detect the buildup of spatial entanglement across the superfluid-insulator transition.
Our experiments open new opportunities for the single-particle-resolved preparation and characterization of many-body quantum states.<br>Physics
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Merlin, Jenny. "Propriétés électrostatiques, mécaniques et chémodynamiques de (bio)interphases molles : analyses en régime d'équilibre et transitoire." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0295/document.
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Dans les milieux naturels, la matière solide est essentiellement présente sous la forme de (bio)particules molles perméables aux ions et aux flux hydriques. Ces particules sont sans cesse soumises à des perturbations électriques/mécaniques, de telle sorte que les propriétés physico-chimiques des (bio)interphases qu'elles forment avec le milieu évoluent continûment dans le temps. Les (bio)interphases ne sont donc pas nécessairement à l'équilibre durant les processus interfaciaux (interactions électrostatiques, complexation de métaux). Dans ce contexte, nous avons évalué théoriquement l'énergie d'interaction électrostatique à l'équilibre entre (bio)particules molles multicouches de tailles et de densités de charge arbitraires. Puis nous avons déterminé l'impact de la dynamique hors-équilibre des propriétés électriques de (bio)films mous ligands sur leur capacité à former des complexes avec des métaux. Le dernier modèle théorique élaboré a pour objectif l'analyse de la dynamique de (bio)interphases multicouches hétérogènes en régimes d'équilibre et hors-équilibre. Enfin nous avons analysé à l'équilibre, en alliant l'AFM et l'électrophorèse, les propriétés mécaniques et électriques de bactéries E. coli exprimant spécifiquement (ou non) des structures de surface différentes. Toutes ces études ont montré la nécessité de prendre en compte pour l'analyse de la réactivité de (bio)particules dans leur milieu environnant (i) une représentation fidèle des (bio)particules (mollesse mécanique et hydrodynamique, hétérogénéité spatiale de la structure molle) et (ii) l'impact de la dynamique spatio-temporelle des (bio)interphases sur les processus gouvernant leur réactivité<br>In natural media, the solid matter is mainly present as soft (bio)particles (bacteria, viruses, humic acids) which are permeable toward ions and hydric fluxes. These (bio)particles are unceasingly exposed to electrical/mechanical perturbations, so that the physicochemical properties of (bio)interphases, developed by (bio)particles with the medium, evolve continuously. (Bio)interphases are thus not necessarily at equilibrium during interfacial processes e.g. electrostatic interactions, complexation with metallic contaminants. Under such a context, we evaluated theoretically at equilibrium the electrostatic interaction energy between soft multilayered (bio)particles with arbitrary sizes and charge densities. We then determined the impact of non- equilibrium electric properties of soft ligand polymeric (bio)films on their ability to form complexes with metals. The aim of the last theoretical model developed here is to analyze the dynamics of multilayered heterogeneous (bio)interphases in both equilibrium and non-equilibrium regimes. Finally we analyzed at equilibrium, by coupling AFM and microelectrophoresis measurements, mechanical and electrical properties of bacterial strains Escherichia coli that specifically express (or not) different surface structures (pili, fimbriae, adhesin Ag43). All these studies highlighted the necessity to integrate for the analysis of (bio)particles reactivity with their surrounding medium (i) a close representation of soft (bio)particles (mechanical and hydrodynamic softness, spatial heterogeneity of the soft material) and (ii) the impact of spatiotemporal dynamics of (bio)interphases on the processes governing their reactivity
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Heidarian, Negar. "A Homologous Study of Lifetimes and Oscillator Strengths of Ultraviolet Transitions in Singly Ionized Lead, Tin, and Germanium." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1500466694480909.
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Zetie, K. P. "Parity non-conservation in atomic bismuth." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315814.
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Kichin, Georgy [Verfasser]. "Submolecular imaging with single particle atomic force sensors / Georgy Kichin." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1064052789/34.
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Kičin, Georgij [Verfasser]. "Submolecular imaging with single particle atomic force sensors / Georgy Kichin." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://nbn-resolving.de/urn:nbn:de:hbz:82-opus-51985.
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Nagose, Atul. "Automated Magnetic Particle Attachment to an Atomic Force Microscope Cantilever." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1262099852.
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Almeida, Tarcísio Silva de. "Determinação de Fe, Cu, Mn, Ni, V e Ti em partículas totais em suspensão coletadas em uma área urbana da cidade de Aracaju, Sergipe." Universidade Federal de Sergipe, 2012. https://ri.ufs.br/handle/riufs/6168.
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This study aimed to determine and assess the total concentration of trace elements associated with the total suspended particles (TSP) collected in an urban area of the Aracaju City, Sergipe, Brazil. Forty two samples were collected on glass fiber filters between period August/2009 and September/2010 using a high volume sampler (AGV). The concentration of Fe, Cu, Mn, Ni, V and Ti were determined employing atomic spectrometry techniques in two different work. The first used acid digestion extraction assisted by microwave and analysis by mass spectrometry and optical emission, both inductively coupled plasma (ICP OES and ICP MS). The concentrations of the elements found between <48 and 1620 ± 16 ng.m-3 for Fe; 0.70 ± 0.04 and 322 ± 4 ng.m-3 for Cu;<1,3 and 12.7 ± 6.8 ng.m-3 for Mn; 1.1 ± 0.1 and 16.0 ± 8.4 ng.m-3 for Ni; <15 and 49.3 ± 4.0 ng.m-3 for V and 4,6 ± 0,6 a 129,0 ± 12,5 ng.m-3 for Ti (n=41 samples). The exploratory data analysis results was applied. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) concluded that there are two emitters that contribute to the composition of the PTS that reach the sampling area. Soil resuspension is major contributor in the composition due to correlation between Fe, Mn, Ni and Ti, which are typical elements of the soil. The second emitter, is characteristic of the vehicular traffic. wherein the concentration of Cu, V, SO2 and smoke were likely indicative of action anthropogenic. The enrichment factor calculated for the concentration of the elements identified enrichment for the average concentration of copper found in the urban area, is another indication of anthropogenic inputs. The second study consisted of the Cu and Fe sequential determination in TSP using slurry sampling flame atomic absorption spectrometry and mode fast sequetial (FS-FAAS). The optimization univariate involved the following variables: the concentration of nitric acid used to prepare the slurry, sonication time and the sample mass. The optimized conditions, to about 50 mg of sample were: nitric acid solution 0.5 mol L-1, sonication time of 10 min and a final volume of 25 mL. The calibration curves were obtained using a slurry of a non-filter, the pattern multielement containing Cu and Fe in nitric acid 0.5 mol L-1. This strategy calibration offset the effect observed for the matrix Fe The limit of detection (LOD, 3σ, n = 10) was equal 4 μg.g-1 for Cu and 14 μg.g-1 for Fe , corresponding to 8 ng.m-3 for Cu and 20 ng.m-3 for Fe. The precison was expressed as relative standard deviation (RSD, n = 3) was smaller than 7% for the copper concentration and 8% for iron concentration in the slurries analysis (n=3). The concentrations of both elements determined by the proposed method were compared to concentrations obtained by ICP-MS after acid extraction assisted by microwave and showed no significant differences, applying the t test for a confidence level of 95%. The proposed procedure was simple, fast and reliable suitable for the sequential determination of Cu and Fe in PTS samples by FS-FAAS.<br>Este trabalho teve como objetivo determinar e avaliar a concentração total de elementos traço associados as partículas totais em suspensão (PTS) coletadas em uma área urbana da cidade de Aracaju, Sergipe, Brasil. Quarenta e duas amostras foram coletadas em filtros de fibra de vidro no período entre agosto/2009 e setembro/2010 utilizando um amostrador de grande volume (AGV). As concentrações de Fe, Cu, Mn, Ni, V e Ti foram determinadas empregando-se técnicas de espectrometria atômica em dois trabalhos distintos. O primeiro usou a digestão ácida assistida por micro-ondas e análise por espectrometria de massa e de emissão óptica, ambas com plasma indutivamente acoplado (ICP-MS e ICP OES). Foram encontradas as concentrações entre <48 a 1620 ± 16 ng g-1 para Fe; 0,70 ± 0,04 a 322 ± 4 ng.m-3 para Cu; 1,3 a 12,7 ± 6,8 ng.m-3 para Mn; 1,1 ± 0,1 a 16,0 ± 8,4 ng.m-3 para Ni, <15 a 49,3 ± 4,0 ng.m-3para V e 4,6 ± 0,6 a 129,0 ± 12,5 ng.m-3. Foi aplicada a análise exploratória de dados aos resultados. A partir da análise de componentes principais (PCA) e a análise de agrupamentos hierárquicos (HCA) concluiu-se que há dois emissores que contribuem na composição do PTS que atingem a área amostral. A ressuspensão do solo é o maior contribuidor na composição química, devido correlação encontrada entre Fe, Mn, Ni e Ti, que são elementos tipicos do solo. O segundo emissor é caracteristico do trafego veicular, onde a concentração de Cu, V, SO2 e Fumaça foram prováveis indicativos de ação antropogênica. O fator de enriquecimento calculado para a concentração dos elementos identificou o enriquecimento para a concentração de cobre encontrada na área urbana, sendo outro indicativo da ação antropogênica. O segundo trabalho consistiu da determinação sequencial de Cu e Fe no PTS usando amostragem em suspensão e espectrometria de absorção atômica com chama no modo seqüencial rápido ( fast sequential ) multi-elementar (FS-FAAS). A otimização univariada envolveu as seguintes variáveis: concentração da solução de ácido nítrico usada no preparo da suspensão, tempo de sonicação e massa da amostra. As condições otimizadas, para cerca de 50 mg de amostra, foram: solução de ácido nítrico 0,5 mol.L-1, tempo de sonicação de 10 min e um volume final de 25 mL. As curvas de calibrações foram obtidas, usando-se uma suspensão de um filtro não utilizado, contendo o padrão multielementar de Cu e Fe em meio de ácido nítrico 0,5 mol.L-1. Esta estratégia de calibração compensou o efeito de matriz verificado para o Fe. O limite de detecção (LD, 3σ, n=10) do método proposto foi igual a 4 μg.g-1 para Cu e igual a 14 μg.g-1 para Fe, que corresponde a 8 ng.m-3 para Cu e a 20 ng.m-3 para Fe. A precisão, expressa como o desvio padrão relativo (RSD, n=3), foi menor do que 7% para a concentração de Cu e a 8% para a concentração de Fe na análise das suspensões. As concentrações de ambos os elementos determinados pelo método proposto foram comparadas com as concentrações obtidas por ICP-MS após extração ácida assistida por micro-ondas e não apresentaram diferenças significativas, aplicando-se o teste t para um nível de confiança de 95%. O procedimento proposto é simples, rápido e confiável, adequado para a determinação sequencial de Cu e Fe em amostras de PTS por FS-FAAS.
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Edmonds, Matthew James. "Simulation of single and many particle gauge theories with ultracold atomic gases." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2799.
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The study of systems formed from ultracold atomic gases has emerged to become one of the most active research elds within the condensed matter landscape. These highly controllable macroscopic systems amalgamate ideas from many sub disciplines of physics, including the study of low temperatures, quantum optics and quantum information theory as well as the seemingly disparate eld of high energy physics. The central concept of this thesis is gauge theories as applied to systems of bosonic atoms, which at temperatures close to absolute zero form Bose-Einstein condensates. To simulate the mathematical structure of a gauge theory, the geometric (Berry) phase formalism is adopted. This is in turn accomplished by considering the adiabatic following of the eigenstates of the light-matter coupling for an ensemble of atoms forming a Bose-Einstein condensate. These concepts are then applied to show how one can generate a spin-orbit coupling in a one-dimensional condensate, which additionally features a random mass term that allows us to study the physics of Anderson localization in an intriguing \quasi" relativistic regime. One of the features of light induced gauge potentials is that they are static; in the sense that there is no feedback between the light-matter interaction and the matter eld. In the second part of this thesis it is demonstrated how such a feedback mechanism can be induced by the appropriate modi cation of the light-matter interaction. The consequences this has for the condensate are then described at the mean- eld level, including the expected experimental signatures of the resulting `interacting' gauge theory, in terms of the expansion of the condensate and also the structure of the solitons of this nonlinear system. Finally, this nonlinear model is applied to a double well system, from which the associated Bose-Hubbard model is derived and analysed; and the nonlinear Josephson problem studied.
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Møller, Morten. "Optimizing the structure of scanning probes for atomic manipulation." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/44916/.
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Scanning probe microscopy (SPM) allows us to directly measure the interactions between a probe and a sample at the atomic scale. Techniques such as non-contact atomic force microscopy (NC-AFM), allows us to to characterize the forces present on a surface, resolve the atomic structure of molecules or examine their chemical properties, while scanning tunneling microscopy (STM) allows their electronic properties to be characterized. As the interactions take place at the atomic scale, the atomistic state of the probe apex plays a crucial role. In AFM, it is the atomic scale forces between the outermost atoms of the probe and surface that are dominant, while for STM the density of states (DOS) that contribute to tunneling are crucial. Therefore, understanding and controlling the tip termination is crucial to derive meaningful interpretations from experimental data. In this thesis, the role of the tip termination is examined for various surfaces and situations. We find that determining the "right" tip state depends critically on the experiment and several general strategies for shaping the tip apex into a preferred state are therefore outlined. H:Si(100) surfaces were used as a substrate for lithographic patterning using STM. We have successfully implemented an automated extraction routine for performing large scale patterning with high fidelity and single atom specificity. Our ultimate goal is to combine the extraction routine with SPM image recognition software to allow analysis and manipulation of atomic scale features without human intervention. To perform manipulations reliably, the tip influence on "what we see" (tip imaging states), or specifically on what the recognition software can identify, needs to be considered. We find, counter-intuitively, that atomic scale manipulation with the highest fidelity occurs when silicon dimers are observed as rows as opposed to when atomic resolution imaging occurs. The tip state influence on measuring surface diffusion of PTCDA on Ag(110) surfaces, was also investigated. We find that the adsorption kinetics of diffusing molecules can only be detected for specific tip imaging states. To allow examination with no-human intervention, the tip state needs to be carefully considered, and a combination of analytical and spectroscopic tools needs to be implemented in conjunction with the experiment. Additionally, characterization of the tip apex was investigated at the tunnel junction between a STM tip and a metal surface using field emission measurements. Our results suggest that field emission measurements performed at the tunnel junction are sensitive to changes in the nanoscopic/mesoscopic tip apex structure, thus opening up the possibility of automating the process of characterization the tip apex.
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Nesbitt, Brian. "Heavy-particle collisions." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301028.
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Greenaway, Mark Thomas. "Single particle and collective dynamics in periodic potentials." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11517/.
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In this thesis, we describe, both semiclassically and quantum mechanically, the single-particle and collective dynamics of electrons and ultracold atoms moving through periodic potentials. Firstly, we explore collective electron dynamics in superlattices with an applied voltage and tilted magnetic field. Single electrons in this system exhibit non-KAM chaotic dynamics. Consequently, at critical field values, coupling between Bloch and cyclotron motion causes delocalisation of the electron orbits, resulting in strong resonant enhancement of the drift velocity. We show that this dramatically affects the collective electron behaviour by inducing multiple propagating charge domains and, consequently, GHz-THz current oscillations with frequencies ten times higher than with no tilted field. Secondly, we study the effect of applying an acoustic wave to the superlattice and find that we can induce high-frequency single electron dynamics that depend critically on the wave amplitude. There are two dynamical regimes depending on the wave amplitude and the electron's initial position in the acoustic wave. Either the electron can be dragged through the superlattice and is allowed to perform drifting periodic orbits with THz frequencies far above the GHz frequencies of the acoustic wave; or, by exerting a large enough potential amplitude, Bloch-like oscillations can be induced, which can cause ultra-high negative differential velocity. We also consider collective electron effects and find that, generally, the acoustic wave drags electrons through the lattice. Additionally, high negative differential drift velocity at the transition between these two single-electron dynamical regimes, induces charge domains in the superlattice that generates extra features in the current oscillations. Finally, we investigate cold atoms in optical lattices driven by a moving potential wave, directly analogous to acoustically-driven superlattices. In this case, we find the same dynamical regimes found in the acoustically driven superlattice. In addition, there are a number a sharp resonant features in the velocity of the atom at critical wave amplitudes and speeds. This could provide a flexible mechanism for transporting atoms to precise locations in a lattice.
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Aston, David Eric. "Quantifying single oil-particle interactions in aqueous media /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/9898.
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