Дисертації з теми "Probe structure"
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1
Jalloh, Muneer. "Probe diffusion and nanoscale structure in block copylymer hydrogels." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522408.
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Shin, Edward Matthew. "Strong gravitational lensing as a probe of galaxy structure." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612310.
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Le, Jenny Vi Le. "Tunable Nanocalipers to Probe Structure and Dynamics in Chromatin." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543163132011865.
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Liu, Richard Yufeng. "Oxygen Transport as a Structure Probe for Amorphous Polymeric Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1103694304.
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Hu, Yushan. "OXYGEN TRANSPORT AS A STRUCTURE PROBE FOR HETEROGENEOUS POLYMERIC SYSTEMS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1112902488.
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Yang, Emma. "Chemical, metabolic and structure-activity relationships to probe abacavir toxicity." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2008286/.
Повний текст джерелаАнотація:
Adverse drug reactions (ADRs) are responsible for an increasing number of hospitalised patients, with the large majority of these ADRs classed as either type A or type B. Drug hypersensitivity reactions fall within the type B category and one such drug responsible for this form of ADR is abacavir (ABC). ABC, a nucleoside reverse transcriptase inhibitor, is used to treat the HIV-1 virus. It is responsible for a potentially life-threatening type IV hypersensitivity reaction which occurs in patients bearing the HLA-B*57:01 allele. Although many mechanisms have been proposed, it was the objective of this research to examine all these previous proposals to further extend and develop the mechanism of ABC toxicity. In Chapter 2, deuterated-ABC (D2-ABC) was designed and synthesised where the two 5'-H atoms were replaced with two 5'-D atoms. The design of this analogue was intended to retard the oxidative metabolism of ABC to its aldehyde and carboxylic acid metabolites. The synthesis of this compound was paramount to investigating this metabolism and through a series of metabolic experiments, described in Chapter 3, a kinetic isotope effect between ABC and D2-ABC was determined, ultimately showing an altered metabolism between the two compounds. To investigate binding of ABC within the HLA-B*57:01 protein, analogues of ABC, with alterations at varying positions within the molecule, were required. Using a racemic method, ABC enantiomers were synthesised and ABC’s enantiomer failed to stimulate T-cells in vitro. The creation of further analogues required the development of an asymmetric synthetic route. A total synthetic method was desired to synthesise intermediates to be used in future analogue synthesis. Finally, as described in Chapter 5, a range of 6-position analogues were designed, using a structure-activity relationship method, and synthesised, to further investigate the altered repertoire mechanism. These analogues, consisting of primary and secondary amine and oxy moieties, were subjected to in vitro immunological assays to determine their stimulation of T-cells. Additionally, the synthesised analogues were modelled in silico using molecular docking within the HLA protein. The in silico results assisted in explaining the basis of such T-cell activation/inactivation and will direct future analogue design. IC50 and EC50 values were determined for analogues that presented a negative T-cell response and a compound showing positive values was subjected to further pharmacokinetic testing. The oxidative metabolism of ABC was affected by isotopic substitution, but initial results have shown no altered T-cell stimulation of D2-ABC compared to ABC. This mechanism cannot be discarded, with further investigational work required. However, the synthesised 6-position analogues have assisted in further examining the altered repertoire mechanism and initial findings have enabled further understanding of the binding of ABC within HLA-B*57:01. This mechanism of ABC toxicity appears paramount to others proposed and the results presented in this thesis support this. Additional analogue synthesis and in vivo experiments will assist in confirming this further.
7
Romero, G. E., S. P. Owocki, A. T. Araudo, R. H. D. Townsend, and P. Benaglia. "Using gamma-rays to probe the clumped structure of stellar winds." Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1821/.
Повний текст джерелаАнотація:
Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar wind in the subclass of massive X-ray binaries known as “microquasars”. The relativistic jet is ejected from the surroundings of the compact object and interacts with cold protons from the stellar wind, producing pions that then quickly decay into gamma-rays. Since the resulting gamma-ray emissivity depends on the target density, the detection of rapid variability in microquasars with GLAST and the new generation of Cherenkov imaging arrays could be used to probe the clumped structure of the stellar wind. In particular, we show here that the relative fluctuation in gamma rays may scale with the square root of the ratio of porosity length to binary separation, $sqrt{h/a}$, implying for example a ca. 10% variation in gamma ray emission for a quite moderate porosity, h/a ∼ 0.01.
8
Vaumousse, David. "An atom probe study of fine scale structure in A1MgSi(Cu)." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401025.
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Orbai, Lucian. "Using nucleic acid chemistry to probe telomeric DNA function and structure /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Cavanagh, Molly Christine. "Using the ultrafast pump-probe spectroscopy of atomic anions and the solvated electron to probe solvent structure and solvation dynamics." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1581642021&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Ju, Yang, Atsushi Hosoi, Lan Zhang, and Akifumi Fujimoto. "Structure Modification of M-AFM Probe for the Measurement of Local Conductivity." IEEE, 2010. http://hdl.handle.net/2237/14489.
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Becker, Andrew Cameron. "Exotic gravitational microlensing effects as a probe of stellar and galactic structure /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5427.
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Shrive, Jason David Alderson. "Artificial phospholipid membrane biosensor design, optimization of fluorescent probe loading and membrane structure." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ51531.pdf.
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Soumyanarayanan, Anjan. "A nanoscale probe of the quasiparticle band structure for two dimensional electron systems." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83821.
Повний текст джерелаАнотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.Page 138 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 121-137).
The advent of a broad class of two-dimensional (2D) electronic materials has provided avenues to create and study designer electronic quantum phases. The coexistence of superconductivity, magnetism, density waves, and other ordered phases on the surfaces and interfaces of these 2D materials are governed by interactions which can be experimentally tuned with increasing precision. This motivates the need to develop spectroscopic probes that are sensitive to these tuning parameters, with the objective of studying the electronic properties and emergence of order in these materials. In the first part of this thesis, we report on spectroscopic studies of the topological semimetal antimony (Sb). Our simultaneous observation of Landau quantization and quasiparticle interference phenomena on this material enables their quantitative reconciliation - after two decades of their study on various materials. We use these observations to establish momentum-resolved scanning tunneling microscopy (MR-STM) as a robust nanoscale band structure probe, and reconstruct the multi-component dispersion of Sb(111) surface states. We quantify surface state parameters relevant to spintronics applications, and clarify the relationship between bulk conductivity and surface state robustness. At low momentum, we find a crossover in the single particle behavior from massless Dirac to massive Rashba character - a unique signature of topological surface states. In the second part of this thesis, we report on the spectroscopic study of charge density wave (CDW) order in the dichalcogenide 2H-NbSe2 - a model system for understanding the interplay of coexisting CDW and superconducting phases. We detail the observation of a previously unknown unidirectional (stripe) CDW smoothly interfacing with the familiar triangular CDW on this material. Our low temperature measurements rule out thermal fluctuations and point to local strain as the tuning parameter for this quantum phase transition. The distinct wavelengths and tunneling spectra of the two CDWs, in conjunction with band structure calculations, enable us to resolve two longstanding debates about the anomalous spectroscopic gap and the role of Fermi surface nesting in the CDW phase of NbSe2. Our observations motivate further spectroscopic studies of the phase evolution of the CDW, and of NbSe 2 as a prototypical strong coupling density wave system in the vicinity of a quantum critical point.
by Anjan Soumyanarayanan.
Ph.D.
15
Naden, Aaron Benjamin. "Resolving structure-function relations in advanced materials by scanning probe and electron microscopies." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6857/.
Повний текст джерелаАнотація:
Understanding the links between structural and functional properties is at the heart of materials science and underpins the development of technologically relevant materials. The work presented in this thesis is primarily concerned with development of these links in two distinct material classes by scanning probe and electron microscopies. After a brief overview of the background and instrumentation (Chapters 1 and 2), Chapter 3 concerns the development of structure-function relations in bottom gate, bottom contact organic transistors employing an active layer comprising a blend of diF-TES-ADT and a polystyrene-like binder. These devices are shown to exhibit electrical performances that are competitive with equivalent amorphous Si (a-Si) devices. The nucleation and growth processes of the semiconductor film, leading to the formation of four structurally distinct crystalline diF-TES-ADT regimes, are described, including evidence of layer-by-layer growth when solution processed. These crystalline regimes – or regions of growth – are linked to electrical characteristics by study of a variety of different device components. One of these regions of growth – region D, the 3D crystals – does not appear to have been previously reported for diF-TES-ADT. The structure-function links are enhanced by direct visualisation of the potential drop across the channel of devices using scanning Kelvin probe force microscopy. The different crystalline regimes are rationalised in the context of a first kinetic description of the film formation process, which can be used to make predictions with regards to device optimisation for more commercially viable, shorter channel length devices. In Chapter 4, advanced specimen preparation protocols by means of a focused ion beam instrument are addressed; followed by the applicability, advantages and limitations of electron microscopy for the study of organic transistors, employing electron energy loss spectroscopy. Issues of phase segregation and intermixing are addressed in this context, with a combination of atomic force and electron microscopies proving to be particularly successful. The possibility of identifying different organic materials in the absence of unique elements is explored by investigation of spectroscopic fine structure and plasmon energy analysis using electron energy loss spectroscopy. The ability to assess such issues with nanometre resolution is pivotal to developing a thorough and detailed understanding of this class of device. Chapter 5 considers an entirely separate class of materials, functional metal oxides. An analysis protocol is developed for the quantified assessment of moire fringes arising in scanning transmission electron microscopy. Here, a rigorous and robust mathematical description of the technique is developed and a method for accurate quantification of data is demonstrated. The assessment of strain over large fields of view is investigated and the ability to identify dislocations within crystalline specimens by STEM moire is shown for the first time. Assessment of crystallographic strain over large fields of view with high precision is important for developing structure-function relations of functional oxides since their properties can be carefully controlled by strain engineering. The studies presented here represent an important step forward in understanding this attractive approach.
16
Hicks, Robert Paul. "Probing Electrocatalytic and Photocatalytic Processes with Structure-Specific Spectroscopies:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108657.
Повний текст джерелаАнотація:
Thesis advisor: Matthias M. WaegeleStudying the adsorption and reaction kinetics of surface-bound chemical species, on different metal catalysts or electrodes, is of paramount importance in the development of inhomogeneous catalytic methodology. Our study of the oxidation of CO on platinum was accomplished by designing a thin layer flow cell in an external reflection configuration. A charge-injection circuit was successfully implemented which decreased the time required to charge the double layer in the electrochemical cell. We were able to obtain a signal via Stark shift spectrum, of the adsorbed CO, using the thin layer cell configuration. Additionally, electrochemical impedance spectroscopy was used as a diagnostic tool to assess the effect of electrode geometry, on the voltage response, in the thin layer cell. The coupling of visible light-driven photoexciation with transition metal catalytic plat- forms is emerging as a synthetic strategy to achieve unique reactivity that has previously been inaccessible. One such example is the iridium/nickel-dipyridyl system discovered recently. Characterizing the interactions between the iridium and nickel catalysts, under reaction conditions, is important to develop a better understanding of the system. In order to apply infrared spectroscopic measurement techniques, in-situ, we made modifications to the synthetic scheme by changing the solvent and by utilizing different iridium catalysts for the synthesis of the desired methyl 4-(benzoyloxy)benzoate product. Using our trans- mission infrared setup we effectively demonstrated in-situ product detection of the aryl- ester coupled product. Additionally, after constructing a transient infrared pump-probe setup, we collected preliminary results of the triplet state lifetime of the iridium dye. The surface morphology of copper has been shown to affect the electrochemical reduction of CO2. Using surface-enhanced Raman spectroscopies, the reversible formation of nanoscale metal clusters on a copper electrode was revealed at sufficiently cathodic potentials where we observed the appearance of a new band at 2080 cm-1 corresponding to C≡O adsorbed to undercoordinated copper defect sites. The formation of new undercoordinated sites additionally resulted in the surface enhancement of the Raman scattering which amplified the intensity of the other spectral bands
Thesis (MS) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
17
Yu, Minzi. "Positron annihilation spectroscopy as a probe of microscopic structure and physical aging in polymer." Case Western Reserve University School of Graduate Studies / OhioLINK, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=case1056474218.
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Davoli, Guido. "Galaxy-galaxy strong lensing as a probe of the inner structure of galaxy clusters." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13969/.
Повний текст джерелаАнотація:
La disponibilità di osservazioni profonde di ammassi di galassie, ottenute con telescopi spaziali, ha permesso la scoperta di diversi casi di lensing forte che coinvolgono una galassia d'ammasso e una sorgente retrostante (eventi di galaxy-galaxy strong lensing, GGSL). Ciononostante, questo tipo di eventi sembra essere molto raro nelle più recenti simulazioni idrodinamiche di ammassi di galassie. Questo apparente contrasto fra teoria e osservazioni è uno dei motivi che ci hanno spinto ad indagare sulla fenomenologia degli eventi di GGSL negli ammassi di galassie. Inoltre, lo studio delle sottostrutture presenti negli ammassi è di fondamentale importanza per vincolare le proprietà della materia oscura. In particolare, nella presente tesi abbiamo cercato di verificare la possibile esistenza di un collegamento fra le proprietà fisiche degli ammassi di galassie e la probabilità di osservare eventi di GGSL. Abbiamo quantificato questa probabilità definendo la sezione d'urto per il GGSL. Nel corso del lavoro sono state impiegate simulazioni numeriche di lensing da ammassi di galassie, le cui proprietà rispettano le predizioni del modello cosmologico Lambda-CDM. Nel corso della tesi abbiamo messo in luce come alcune proprietà degli ammassi, quali la pendenza del loro profilo di densità, la funzione di distribuzione radiale e la funzione di massa delle sottostrutture influenzino la sezione d'urto. Questi risultati sono stati confermati quando abbiamo applicato la nostra procedura all'ammasso MACSJ1149. Inoltre, grazie al nostro metodo, abbiamo potuto saggiare la validità di due modelli di massa, ottenuti da un'analisi di lensing forte degli ammassi MACSJ1149 e MACSJ1206, confrontando il numero di eventi di GGSL predetti dai modelli con quelli effettivamente osservati.
19
Herrmann, Kristin Ann. "Hydrogen / Deuterium Exchange and Fragmentation of Biomolecules to Probe Gas Phase Structure and Energetics." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1397%5F1%5Fm.pdf&type=application/pdf.
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Ironmonger, Alan. "The design, synthesis and evaluation of chemical libraries that probe RNA structure and function." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434751.
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21
Rosenthal, Colin Samuel. "Sunspots and sunquakes : acoustic oscillations as a probe of magnetic structure in the Sun." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386193.
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Collis, Olivari Lucas. "Intensity mapping : a new approach to probe the large-scale structure of the Universe." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/intensity-mapping-a-new-approach-to-probe-the-largescale-structure-of-the-universe(cd5b7586-7210-441e-838f-545d397893e5).html.
Повний текст джерелаАнотація:
Intensity mapping (IM) is a new observational technique to survey the large-scale structure of matter using emission lines, such as the 21 cm emission line of atomic hydrogen (HI) and the rotational lines of the carbon monoxide molecule (CO). Sensitive radio surveys have the potential to detect the HI power spectrum at low redshifts (z <1) in order to constrain the properties of dark energy and massive neutrinos. Observations of the HI signal will be contaminated by instrumental noise and, more significantly, by astrophysical foregrounds, such as the Galactic synchrotron emission, which is at least four orders of magnitude brighter than the HI signal. In this thesis, we study the ability of the Generalized Needlet Internal Linear Combination (GNILC) method to subtract radio foregrounds and to recover the cosmological HI signal for HI IM experiments. The GNILC method is a new technique that uses both frequency and spatial information to separate the components of the observed data. For simulated radio observations including HI emission, Galactic synchrotron, Galactic free-free, extragalactic point sources and thermal noise, we find that it can reconstruct the HI plus noise power spectrum with 7.0% accuracy for 0.13 <z <0.48 (960 - 1260 MHz) and l <400. In this work, GNILC is also applied to a particular CO IM experiment: the CO Mapping Array Pathfinder (COMAP). In this case, the simulated radio observations include CO emission, Galactic synchrotron, Galactic free-free, Galactic anomalous microwave emission, extragalactic point sources and thermal noise. We find that GNILC can reconstruct the CO plus noise power spectra with 7.3% accuracy for COMAP phase 1 (l <1800) and 6.3% for phase 2 (l <3000). In both cases, we have 2.4 <z <3.4 (26 - 34 GHz). In this work, we also forecast the uncertainties on cosmological parameters for the upcoming HI IM experiments BINGO (BAO from Integrated Neutral Gas Observations) and SKA (Square Kilometre Array) phase-1 dish array operating in auto-correlation mode. For the optimal case of BINGO with no foregrounds, the combination of the HI angular power spectra with Planck results allows w to be measured with a precision of 4%, while the combination of the BAO acoustic scale with Planck gives a precision of 7%. We consider a number of potentially complicating effects, including foregrounds and redshift dependent bias, which increase the uncertainty on w but not dramatically; in all cases the final uncertainty is found to be less than 8% for BINGO. For the combination of SKA-MID in auto-correlation mode (total-power) with Planck, we find that, in ideal conditions, w can be measured with a precision of 4% for the redshift range 0.35 <z <3 (350 - 1050 MHz) and 2% for 0 <z <0.49 (950 - 1421 MHz). Extending the model to include the sum of neutrino masses yields a 95% upper limit of less than 0.30 eV for BINGO and less than 0.12 eV for SKA phase 1, competitive with the current best constraints in the case of BINGO and significantly better in the case of SKA.
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Gouws, Liesbeth-Helena. "Redshift-space distortions as a probe of dark energy." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3342.
Повний текст джерелаАнотація:
>Magister Scientiae - MScWe begin by finding a system of differential equations for the background and linearly perturbed variables in the standard, ɅCDM model, using the Einstein Field Equations, and then solving these numerically. Later, we extend this to dynamical dark energy models parameterised by an equation of state, w, and a rest frame speed of sound, cs. We pay special attention to the large-scale behaviour of Δm, the gauge invariant, commoving matter density, since the approximation Δm ≃ δm, where δm is the longitudinal gauge matter density, is more commonly used, but breaks down at large scales. We show how the background is affected by w only, so measurements of perturbations are required to constrain cs. We examine how the accelerated expansion of the universe, caused by dark energy, slows down the growth rate of matter. We then show the matter power spectrum is not in itself useful for constraining dark energy models, but how redshift-space distortions can be used to extract the growth rate from the galaxy power spectrum, and hence how redshift-space power spectra can be used to constrain different dark energy models. We find that on small scales, the growth rate is more dependent on w, while on large scales, it depends more on cs.
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Greenbaum, Jason Adam. "Experimental and computational studies of DNA structure using the hydroxyl radical as a chemical probe." Thesis, Boston University, 2006. https://hdl.handle.net/2144/30677.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
We have constructed a database of hydroxyl radical (•OH) cleavage patterns of DNA in order to investigate the relationship between the sequence of a DNA molecule and its three-dimensional structure. The hydroxyl radical cuts DNA at every nucleotide, with the amount of cutting proportional to the solvent accessible surface area (SASA) of the deoxyribose hydrogen atoms. Cleavage fragments are quantified by a fluorescence sequencer, followed by normalization and deposition into the database. Our database currently contains 151 DNA sequences with lengths ranging from 35 to 41 nucleotides. These data have enabled us to develop some general rules regarding the sequence-dependence of DNA structure as well as to predict the cleavage pattern of any given DNA sequence with remarkable precision. Using this prediction algorithm, it is possible to construct structural maps of entire genomes. As there are many examples of DNA binding proteins with highly degenerate binding sites, the use of structural information to locate these sites may be helpful. There also exists other signals, including the signal for nucleosome positioning, which have no apparent consensus, making it likely that the structure of DNA is of critical importance. We have developed algorithms to identify regions of conserved structure using •OH cleavage intensity as a proxy. Within a set of DNase I hypersensitive sites (DHS) obtained from the ENCODE Consortium, we were able to identify a stretch of 12 nucleotides for which the structural conservation is much greater than the sequence conservation. These sites have been dubbed Conserved •OH Radical Cleavage Signatures, or CORCS. Upon further analysis, these CORCS were found to be 17-fold enriched for DHS as compared to shuffled elements. Through the continued analysis of hydroxyl radical cleavage data and development of algorithms to employ the data in biologically meaningful ways, we hope to further our understanding of the relationship between DNA sequence and structure, and how the local structural heterogeneity of genomic DNA contributes to biological function.
2031-01-02
25
Hanyu, Yuki. "Chemical scanning probe lithography and molecular construction." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:409308ed-4806-44fc-87c3-5c1fe8971f79.
Повний текст джерелаАнотація:
The initiation and high resolution control of surface confined chemical reactions would be both beneficial for nanofabrication and fundamentally interesting. In this work, spatially controlled scanning probe directed organometallic coupling, patterned functional protein immobilisation and highly localised reversible redox reactions on SAMs were investigated. Catalytically active palladium nanoparticles were mounted on a scanning probe and an appropriate reagent SAM was scanned in a reagent solution. This instigated a spatially resolved organometallic coupling reaction between the solution and SAM-phase reagents. Within this catalytic nanolithography a spatial resolution of ~10nm is possible, equating to zeptomole-scale reaction. The methodology was applied to reactions such as Sonogashira coupling and local oligo(phenylene vinylene) synthesis. By altering the experimental protocols, relating probe scan velocity to reaction yield and characterising the nanopattern, a PVP matrix model describing a proposed mechanism of catalytic nanolithography, was presented. Though ultimately limited by probe deactivation, calculations indicated that activity per immobilised nanoparticle is very high in this configuration. For biopatterning, surface nanopatterns defined by carboxylic functionality were generated from methyl-terminated SAMs by local anodic oxidation (LAO) initiated by a conductive AFM probe. By employing suitable linker compounds, avidin and Stefin-A quadruple Mutant (SQM) receptive peptide aptamers were patterned at sub-100nm resolution. The multiplexed sensing capability of an SQM array was demonstrated by reacting generated patterns with single or a mixture of multiple antibodies. The reversible redox conversion and switching of reactivity of hydroquinone-terminated SAMs was electrochemically demonstrated prior to an application in redox nanolithography. In this methodology, spatially controlled probe-induced in situ "writing" and "erasing" based on reversible redox conversion were conducted on hydroquinone terminated SAM. In combination with dip-pen nanolithography, a novel method of redox electro-pen nanolithography was designed and the method’s application for lithography was examined.
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Brauße, Felix [Verfasser]. "Shape Resonances as a Probe of an Evolving Nuclear and Electronic Structure in Molecules / Felix Brauße." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/117977857X/34.
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Fredén, Linnéa. "Characterization of the fusion protein mNG-Aβ1-42 as a fluorescence reporter probe for amyloid structure". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-167167.
Повний текст джерелаАнотація:
Alzheimer’s Disease, also called AD, is a horrible, degenerative brain disease that more than 35 million people over the world have. Today, there is no cure for this disease, only treatments that are temporarily relieving the symptoms. The two proteins that is thought to be the main cause of AD is amyloid β (Aβ) and tau. Previously, people have tried studying Aβ in vivo using green fluorescent protein fusion together with Aβ. However, this is difficult since the aggregation of Aβ will lead to loss of fluorescence. This study aimed to crystallize the fusion protein mNG-A β1-42 and to investigate its properties as a molecular fluorescent Aβ-amyloid specific probe. Dynamic light scattering (DLS) was used to confirm that the majority of the protein was not in the form of soluble aggregates. The DLS experiments were followed by several rounds of crystallization trials. Initial screening and the subsequent narrowing down of potential conditions where mNG-Aβ1-42 could form crystals. Several staining experiments were conducted as well, including staining brain tissue from mouse with both Swedish and Arctic mutation, from human patients with sporadic AD and from human patients with AD with the Arctic mutation. The DLS experiments showed that the protein used in the crystallization experiments mostly consisted of molecular particles of the same radius. However, there was clear evidence of some larger species present that could have been a potential problem for crystallization. Crystallization experiments suggested that PEG 8000 was the most promising precipitant amongst other conditions identified for crystallization of mNG-Aβ1-42. However, the study was ultimately unsuccessful in developing crystals of sufficient high quality for diffraction studies to commence. The staining experiments demonstrated that mNG-Aβ1-42 could bind both by itself and with another amyloid probe, Congo red, and with antibodies in brain tissue from mouse with both Swedish and Arctic mutation, from human patients with sporadic AD and from human patients with AD with the Arctic mutation. In conclusion, several characteristics of mNG-Aβ1-42 were revealed in this study.
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White, Lee Francis. "Combined nanostructural and isotopic analysis of baddeleyite : new horizons in solar system chronology." Thesis, University of Portsmouth, 2017. https://researchportal.port.ac.uk/portal/en/theses/combined-nanostructural-and-isotopic-analysis-of-baddeleyite(80e4ee98-4090-4801-90f3-ce122bc9270a).html.
Повний текст джерелаАнотація:
Baddeleyite (monoclinic-ZrO2) is an exceptionally common accessory phase in many of the mafic and ultra-mafic rocks prevalent throughout the Solar System. This study presents the first ground-truthing efforts in the development of this robust mineral into a diagnostic indicator, discrete barometer, and precise U-Pb geochronometer of shock metamorphism by combining electron backscatter diffraction and atom probe tomography to generate unique chemical and structural datasets. Microstructural analysis of variably shocked baddeleyite grains around the Sudbury impact structure (Ontario, Canada) highlights a series of crystallographic structures that can be correlated with discrete variations in formative pressure-temperature conditions. Decompression at high temperatures generates a series of interlocking reversion twinned structures, while quenching forms a quasi-amorphous matrix. These features are comparable to those observed in extra-terrestrial samples, where they can be directly linked with the severity and extent of lead loss and age resetting. This finding facilitates the application of baddeleyite as a shock indicator, barometer (>5 GPa) and chronometer in a wide range of planetary materials. This structural variability is also observable on the nanometre scale. Analysis of the most highly shocked Sudbury baddeleyite using atom probe tomography reveals planar and curvi-planar fractures, trace element enriched subgrain boundaries, and solid-state diffusion clusters. These micrometre and nanometre scale features encourage localised diffusion of lead, with whole-microtip U-Pb analyses yielding complex partially reset ages. The application of atom probe tomography allows these features to be spatially resolved on the nanometre scale, yielding highly accurate ages for protolith crystallization and impact metamorphism within a single grain. These results have significant implications for the isotopic analysis of baddeleyite-bearing planetary materials, where the mechanisms of U-Pb age resetting have until now been poorly understood.
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Ratushna, Vladyslava G. "Incorporation of Physico-Chemical Parameters Into Design of Microarray Experiments." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32989.
Повний текст джерелаАнотація:
Microarrays containing long oligonucleotides provide sensitive and specific detection of gene expression and are becoming a popular experimental platform. In the process of designing an oligonucleotide microarray for Brucella, we optimized the overall design of the array and created probes to distinguish among the known Brucella species. A 3-way genome comparison identified a set of genes which occur uniquely in only one or two of the sequenced Brucella genomes. Reverse transcriptase PCR assays of over one hundred unique and pairwise-differential regions identified in Brucella revealed several groups of genes that are transcribed in vivo with potential significance for virulence. The structural and thermodynamic properties of a set of 70mer oligonucleotide probes for a combined B. abortus, B. melitensis and B. suis microarray were modeled to help perform quantitative interpretation of the microarray data. Prediction and thermodynamic analysis of secondary structure formation in a genome-wide set of transcripts from Brucella suis 1330 demonstrated that properties of the target molecule have the potential to strongly influence the rate and extent of hybridization between transcript and an oligonucleotide probe in a microarray experiment. Despite relatively high hybridization temperatures used in the modeling process, parts of the target molecules are predicted to be inaccessible to intermolecular hybridization due to the formation of stable intramolecular secondary structure. Features in the Brucella genomes with potential diagnostic use were identified, and the extent to which target secondary structure, a molecular property which is not considered in the array design process, may influence the quality of results was characterized.Master of Science
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Porredon, Diez de Tejada Anna Maria. "Multi-probe cosmological analysis with the dark energy survey." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669428.
Повний текст джерелаАнотація:
Les actuals i futures cartografies de galàxies cobriran un major volum i recolliran imatges de millor qualitat que les obtingudes fins ara, permetent mesures precises de la última etapa de l'Univers i proves potents de la naturalesa de l’energia fosca i la Relativitat General.
Aquests cartografiats ens permetran obtenir informació cosmològica a partir de diversos observables, i la combinació d'aquests pot millorar la robustesa i precisió dels resultats de l'anàlisi.
Aquesta tesi es centra en la combinació de diferents traçadors de l'estructura a gran escala (LSS) per tal d'obtenir mesures dels paràmetres cosmològics més precises. Primer, combinem la distribució de galàxies de la mostra corresponent al primer any de dades del Dark Energy Survey (DES Y1) amb la distorsió de la radiació còsmica de fons (CMB) deguda a la matèria fosca on viuen aquestes galàxies (CMB lensing) provinent de la combinació òptima entre el South Pole Telescope i Planck. En aquest anàlisi obtenim mesures en el biaix galàctic, la funció de creixement de LSS i paràmetres cosmològics. Els nostres resultats són consistents amb el model estàndard (\LCDM) i altres resultats de DES Y1. La informació que podem obtenir de l'anàlisi està limitada per les restriccions d'escala, però esperem que millori en els futurs anàlisis.
A continuació, combinem la distribució de galàxies de dues mostres diferents (en l'anomenat mètode multi-traçador) per analitzar els senyals de distorsió en la distribució de galàxies deguda a les seves velocitats ``peculiars'' (RSD) i de la possible contribució no-Gaussiana a les fluctuacions inicials de la distribució de matèria (PNG). Per a aquest propòsit, considerem un parell de mostres optimistes (amb gran nombre de galàxies i diferències en el biaix) i les mostres de DES del 3r any d'observacions (DES Y3) que actuaran con a lents gravitatòries. Trobem que les mesures en RSD poden millorar un factor cinc a distàncies properes i les mesures en PNG un factor tres o més. També comprovem l'impacte d'incloure CMB lensing en l'anàlisi, en el qual no variem la cosmologia, trobant que majoritàriament millora les mesures en el biaix.
Per últim, definim i optimitzem una de galàxies limitada en magnitud que s'utilitzarà per les mesures de la distribució de galàxies en l'anàlisi de DES Y3, actuant com a lent gravitacional respecte a galàxies més llunyanes (lens sample). Per aquest propòsit, ens basem en previsions de Fisher i posem a prova com aquestes canvien al variar el nombre de galàxies i la incertesa en la posició donat un conjunt de talls en magnitud. També caracteritzem l'impacte en els nostres resultats de diferents particions de la mostra en intervals de desplaçament al vermell (redshift), tant per aquesta mostra com per l'altra lens sample (REDMAGIC).
Finalment, les nostres previsions mostren que amb aquesta mostra que hem optimitzat podem obtenir mesures un 15\% més precises que amb REDMAGIC.Ongoing and future photometric surveys will enable detailed measurements of the late-time Universe and powerful tests of the nature of dark energy and General Relativity. These surveys will be able to obtain cosmological constraints from multiple probes, and the combination of these probes can improve their robustness and constraining power. This thesis is focused on the combination of multiple tracers of large-scale structure (LSS) to obtain tighter cosmological constraints. First, we combine the galaxy clustering from the Dark Energy Survey (DES) Year 1 (Y1) data with CMB lensing from the optimal combination of South Pole Telescope (SPT) and Planck, obtaining constraints on the galaxy bias, the growth function and the cosmological parameters. Our results are consistent with \LCDM$ $ and other measurements of DES Y1. However, their constraining power is limited due to conservative scale cuts. We expect an improved signal-to-noise in future analyses. We then combine the galaxy clustering of two different galaxy samples (the so-called multi-tracer approach) to explore the constraints on redshift space distortions (RSD) and primordial non-Gaussianities (PNG). For this purpose, we consider a pair of optimistic samples (with large bias differences and number densities) and the DES Year 3 (Y3) lens samples. We find that the constraints on RSD can be improved a factor of five at low redshift with respect to a single tracer, and the constraints on PNG can be improved more than a factor three. We also test the impact of including CMB lensing cross-correlations in our analysis, in which we keep the cosmology fixed, finding it mainly improves the galaxy bias constraints. Last, we define and optimize a magnitude limited galaxy sample to be used for the galaxy clustering measurements in the DES Y3 analysis, in combination with galaxy-galaxy lensing. We rely on Fisher forecasts, and we test how these change given the variations obtained for the number density and estimated redshift uncertainty for a set of magnitude cuts. We also characterize the impact of redshift binning choices in our cosmological constraints for this sample and the other DES Y3 lens sample: REDMAGIC. Finally, our forecasts show that we can potentially obtain 15\% tighter constraints with this magnitude limited sample, compared to REDMAGIC.
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Ruscher, Céline. "The Voronoi liquid : a new model to probe the glass transition." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE027/document.
Повний текст джерелаАнотація:
Comprendre l’origine microscopique du ralentissement de la dynamique au voisinage de la transition vitreuse reste l’un des problèmes fondamentaux de la physique de la matière condensée. Au cours de ce travail, nous introduisons un nouveau modèle de liquide, appelé liquide de Voronoï, et dont les interactions sont directement reliées aux propriétés géométriques des tessellations de Voronoï. Pour cette classe de liquides, les interactions sont à plusieurs corps et agissent de telle sorte que le système est toujours sous tension tout en restant stable. Le but de ce travail est d’étudier un mélange binaire du liquide de Voronoï et de voir de quelles façons ces interactions exotiques affectent le scénario habituel de la transition vitreuse. Tout au long de ce travail, nous caractérisons le liquide de Voronoï bidisperse théoriquement et par le biais des simulations numériques. Nous proposons également des comparaisons avec des liquides de Lennard-Jones surfondus bien décrit dans la littératureUnderstanding the origin of the important slowing down of the dynamics near glass transition is still one of the remaining fundamental problems of condensed matter physics. During this work we introduced a brand-new model of liquids named Voronoi liquid, whose interactions are directly related to the geometrical properties of Voronoi tessellations. For these class of liquids interactions are intrinsically manybody and act in such a way that the liquid is always under tension but remains stable. The aim of this work is to use a binary mixture of the Voronoi liquid to see to what extend these exotic interactions may affect the classical scenario of glass transition. Throughout this work we characterize theoretically and by mean of numerical simulation the bidisperse Voronoi liquid. Comparisons with well-known Lennard-Jones glass formers are systematically performed
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DeGeorge, Vincent G. "Chemical Partitioning and Resultant Effects on Structure and Electrical Properties in Co-Containing Magnetic Amorphous Nanocomposites for Electric Motors." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/885.
Повний текст джерелаАнотація:
chemical partitioning of Cobalt-containing soft magnetic amorphous and nanocomposite materials has been investigated with particular focus on its consequences on these materials’ nanostructure and electrical resistivity. Theory, models, experiment, and discussion in this regard are presented on this class of materials generally, and are detailed in particular on alloys of composition, (Fe65Co35)79.5+xB13Si2Nb4-xCu1.5, for X={0- 4at%}, and Co-based, Co76+YFe4Mn4-YB14Si2Nb4, for Y={0-4at%}. The context of this work is within the ongoing efforts to integrate soft magnetic metal amorphous and nanocomposite materials into electric motor applications by leveraging material properties with motor topology in order to increase the electrical efficiency and decrease the size, the usage of rare-earth permanent magnets, and the power losses of electric motors. A mass balance model derived from consideration of the partitioning of glass forming elements relates local composition to crystal state in these alloys. The ‘polymorphic burst’ onset mechanism and a Time-Temperature- Transformation diagram for secondary crystallization are also presented in relation to the partitioning of glass forming elements. Further, the intrinsic electrical resistivity of the material is related to the formation of virtual bound states due to dilute amounts of the glass forming elements. And lastly, a multiphase resistivity model for the effective composite resistivity that accounts for the amorphous, crystalline, and glass former-rich amorphous regions, each with distinct intrinsic resistivity, is also presented. The presented models are validated experimentally on the Co-containing alloys by Atom Probe Tomography performed through collaboration with Pacific Northwestern National Laboratory.
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Popov, Oleg Igorevich. "Quantum beat spectroscopy of hyperfine structure in the 8p2P3/2 level of atomic cesium." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1344713056.
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Pasdar, Nooshin Alizadeh. "Fluorescent probe and Raman spectroscopic investigation of the effects of pH, heating, and k-carrageenan on whey protein structure." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61051.pdf.
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Renneby, Malin Nicole [Verfasser], and Andreas [Akademischer Betreuer] Burkert. "Weak gravitational lensing as a probe of large-scale structure and galaxy formation / Malin Nicole Renneby ; Betreuer: Andreas Burkert." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1191098303/34.
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Ohmura, Jacqueline (Jacqueline Frances). "Utilizing viruses to probe the material process - structure - property relationship : controlling catalytic properties via protein engineering and nanoscale synthesis." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115761.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 136-146).
From the fabrication of fine chemicals, to the increasing attainability of a non-petrochemical based energy infrastructure, catalysts play an important role in meeting the increasing energy and consumable demands of today without compromising the global health of tomorrow. Development of these catalysts relies on the fundamental understanding of the effects individual catalyst properties have on catalytic function. Unfortunately, control, and therefore deconvolution of individual parameter effects, can be quite challenging. Due to the nanoscale formfactor and wide range of available surface chemistries, biological catalyst fabrication affords one solution to this challenge. To this end, this work details the processing of M13 bacteriophage as a synthetic toolbox to modulate key catalyst parameters to elucidate the relationship between catalyst structure and performance. With respect to electrocatalysis, a biotemplating method for the development of tunable 3D nanofoams is detailed. Viral templates were rationally assembled into a variety of genetically programmable architectures and subsequently templated into a variety of material compositions. Subsequently, this synthetic method was employed to examine the effects of nanostructure on electro-catalytic activity. Next, nanoparticle driven heterogeneous catalysis was targeted. Nanoparticle-protein binding affinities were leveraged to explore the relationship between nanoparticles and their supports to identify a selective, base free alcohol oxidation catalyst. Finally, the surface proteins of the M13 virus were modified to mirror homogeneous copper-ligand chemistries. These viruses displayed binding pocket free copper complexation and catalytic efficacy in addition to recyclability and solvent robustness. Subsequently, the multiple functional handles of the viron were utilized to create catalytic ensembles of varying ratios. Single and dendrimeric TEMPO (4-Carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl) were chemically conjugated to the surface of several catalytically active phage clones further tailoring catalytic function. Taken together, these studies provide strong evidence of the utility of biologically fabricated materials for catalytic design.
by Jacqueline Ohmura.
Ph. D.
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Ågren, Karin. "On the Formation and Structure of the Ionosphere of Titan." Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-172148.
Повний текст джерелаАнотація:
We present results on the ionospheric structure around Titan observed during numerous deep (<1000 km) flybys by the Cassini spacecraft. Our results are based on measurements by the radio and plasma wave science instrument, in particular the Langmuir probe. In addition, data from the magnetometer and electron spectrometer have contributed. The ionosphere of Titan is created when the atmosphere of the moon becomes ionised. There are several mechanisms that contribute to this, the most important of which are considered to be photoionisation by EUV from the Sun with associated photoelectron ionisation, and particle impact ionisation by electrons and ions from Saturn’s corotating magnetosphere. We investigate the influence of the solar zenith angle on the electron number density at the ionospheric peak. The results show on average four times more plasma on the dayside compared to the nightside, with typical densities of 2500 – 3500 cm-3 and 400 – 1000 cm-3, respectively. In a complementary study, we make a case study of a nightside flyby and show that the altitude structure of the deep ionosphere is reproducible by a simple electron impact ionisation model. Taken together, this leads to the conclusion that solar photons are the main ionisation source of the dayside ionosphere. However, magnetospheric particle precipitation also contributes and can explain the electron densities seen on the nightside. As Titan does not exhibit any large intrinsic magnetic field, the fact that it is embedded in the magnetosphere of Saturn means that the Kronian field drapes around the moon and gives rise to an induced magnetosphere. We show that there are currents of the order of 10 – 100 nA m-2 flowing in the ionosphere of the moon. Associated with the currents are perpendicular electric fields ranging from 0.5 to 3 µV m-1. Finally, we investigate measurements obtained during T70, the deepest Titan flyby performed to date. We show that there is a substantial amount of negative ions present below an altitude of 900 km. This confirms previous result by the electron spectrometer, showing negative ions at higher altitudes in Titan’s ionosphere.
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Schütte, Ole Mathis. "Structure and dynamics of artificial lipid membranes containing the glycosphingolipid Gb3." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://hdl.handle.net/11858/00-1735-0000-0023-960D-7.
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Meyer, Roland [Verfasser]. "Antioxidant Activity Measured by Fluorescence Investigation of Antioxidant and Probe Structure as well as their Mobility and Position / Roland Meyer." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2012. http://d-nb.info/1035217228/34.
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Burgess, Kevin. "Solid-State Nuclear Magnetic Resonance of Exotic Quadrupolar Nuclei as a Direct Probe of Molecular Structure in Organic Ionic Solids." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/31971.
Повний текст джерелаАнотація:
In the past decade, the field of NMR spectroscopy has seen the emergence of ever more powerful superconducting magnets, which has opened the door for the observation of many traditionally challenging or non-receptive nuclei. In this dissertation, a variety of ionic solids with organic coordination environments are investigated using quadrupolar solid-state NMR experiments with an ultrahigh-field magnet (21.1 T). Two general research directions are presented including a 79/81Br solid-state NMR study of a series of 6 triphenylphosphonium bromides for which single-crystal X-ray structures are reported herein. A second research direction is also presented wherein alkaline-earth metal (25Mg, 43Ca, and 87Sr) solid-state NMR is used to characterize a systematic series of 16 aryl and alkyl carboxylates. In both studies, the quadrupolar nuclei studied are deemed “exotic” due to their unreceptive nature to NMR spectroscopic analysis including low natural abundances, large quadrupole moments, or low resonance frequencies. A variety of coordination modes to alkaline-earth metals, including N-atom coordination, are characterized herein for the first time using alkaline-earth metal solid-state NMR. In all cases, the electric field gradient (EFG) and chemical shift (CS) tensors are characterized and correlated to structural features such as interatomic distances measured from the crystal structure of the compound under study.
In all of the projects undertaken herein, the gauge-including projector-augmented-wave density functional theory (GIPAW DFT) method is used, which allows for the prediction and rationalization of the experimental EFG and CS tensor parameters based on the input crystal structure. In the case of 43Ca solid-state NMR experiments reported in this dissertation, a linear correlation between the calculated and experimental 43Ca quadrupolar coupling constants, CQ, is used as a calibration curve for GIPAW DFT calculations performed on the 18 structural models currently available for the vaterite polymorph of CaCO3. Vaterite cannot be fully characterized by X-ray diffraction alone; therefore an NMR crystallography protocol is used in order to identify the model that best accounts for 43Ca solid-state NMR experiments performed on vaterite. It is expected that the conclusions from this dissertation can be used for future studies involving structural refinement and elucidation of solid materials containing challenging quadrupolar nuclei.
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Zandbergen, Mathijs Willem. "Study of early-stage precipitation in Al-Mg-Si(-Cu) alloys by 3D atom probe." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:ae2ab6c5-6e0a-4a3c-902b-d05596e5f4a3.
Повний текст джерелаАнотація:
Hardness measurements and Three-Dimensional Atom Probe (3DAP) were used to characterize the early stages of precipitation in three different Al-Mg-Si alloys (Al-0.50 wt%Mg-1.00 wt%Si) with different Cu contents (0.03 wt%, 0.15 wt%, or 0.80 wt% Cu). Heat treatments were chosen to simulate an industrial production line for car body-sheet material and included natural ageing (NA), pre-ageing at 80 °C (PA), paint-bake ageing at 180 °C (PB) and 10 second ageing at 180 °C (spike). The Cu content and the chosen heat treatments were found to influence the microstructural evolution of the alloy considerably. Based on the determined microstructures and matrix solute concentrations, mechanisms for the effect of NA, PA and Cu additions were proposed. NA had a deleterious effect on the PB hardening response, which was delayed dramatically after 20 minutes NA or longer. When the NA time was 1 minute, β" precipitates were formed within 30 minutes PB resulting in high hardness of the alloy. The delay with NA time was caused by a decrease in the nucleation rate of elongated precipitates during the subsequent PB. This decrease was thought to be due to a combination of a decrease in the matrix solute concentrations and clusters acting as vacancy sinks. PA before NA improved the PB response due to the formation of a high density of short elongated precipitates. Small Mg-Si clusters were detected after both NA and PA. Clusters formed during PA were found to be, on average, Mg-richer and larger than those formed during NA. Larger clusters were found to be more stable during PB and, upon PB, to grow into nucleation sites for elongated precipitates. Application of a spike before PA resulted in faster growth of clusters during PA. Growth of clusters and nucleation of short elongated precipitates during PB was found to be enhanced with increasing Cu content when no PA was given. Cu was found to be present in all precipitates and clusters in the alloy with the highest Cu content. These precipitates were thought to be precursors to the Q' phase.
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Holmes, Richard James. "Chemical modification of activated carbon adsorbents." Thesis, Brunel University, 1991. http://bura.brunel.ac.uk/handle/2438/5378.
Повний текст джерелаАнотація:
Activated carbons have been modif fed using reactive chemicals to produce adsorbents of enhanced hydrophobic character which will also be resistant to surface oxidation that results from exposure to humid air ("ageing"). The intention was that modification would not disrupt the carbon pore structure. The adsorptive properties of the modified carbons have been investigated using probe molecules Including nitrogen, water, hexane, and chloropicrin, and the ageing characteristics of the carbons, and the factors controlling the adsorption of a model hydrophobic vapour from high humidity air have been studied. Directly fluorinated carbons were unstable, probably due to weakly adsorbed fluorine. Treatment of these adsorbents with other chemicals indicated the potential of the technique for Introducing specific functional groups onto the carbon surface. Carbons modified using selective fluorinating reagents (hexafluoropropene and 1,1-difluoroethene) were more hydrophobic, and adsorbed hydrophobic vapours more efficiently from humid air in comparison to controls. These adsorbents aged, but at a reduced rate in comparison to control carbon. Carbons modified using chlorinating reagents (carbonyl chloride and chlorine) and treated with solvents to remove adsorbed reagent and/or reaction products were of improved hydrophobic character, and adsorbed hydrophobic vapours from humid air at least as efficiently as the control samples. More importantly, these carbons offered resistance to ageing effects. A study of the factors controlling the efficiency with which hydrophobic vapours; are adsorbed from humid air revealed that the surface chemistry of the carbon is important, but that under typical conditions of use, filter performance was limited by the rate at which water displaced by the organic vapour could be carried away by the airstream. The results illustrate that filters containing chemically modified activated carbon offer advantages when volatile hydrophobic contaminant vapours are present, and where ageing effects are an important mechanism by which filtration efficiency is degraded.
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McCulla, James K. "Dating Deformation in the Palmer Zone of Transpression, Central Massachusetts: Temporal Constraints on Models for Progressive Deformation in the Middle Crust." UKnowledge, 2016. http://uknowledge.uky.edu/ees_etds/34.
Повний текст джерелаАнотація:
The Palmer Zone of Transpression (PZoT) in the Bronson Hill zone of central Massachusetts is an expression of late Paleozoic oblique convergence between Avalonia and Laurentia. The steeply W-dipping, N-S trending PZoT is defined by bounding high strain zones (Mt. Dumplin on west, Central Maine and Conant Brook on east) of opposing shear sense enclosing the Monson orthogneiss. Research was designed to establish the timing of deformation to test the hypothesis that strain in transpressional systems occurs contemporaneously. An understanding of the timing of deformation in this zone could elucidate the mechanisms that formed the zone and contribute to a greater overall understanding of fabric evolution in transpressional systems. U-Pb SIMS ages of zircon in deformed pegmatites in Monson orthogneiss and Paxton and Rangeley paragneisses are 369 to 364 Ma. Plutons that contain all fabrics associated with progressive transpression – lineations ranging from subhorizontal (initial) to steeply-plunging parallel to dip (final) – mark the maximum age of deformation. Ages range from 360-355 Ma in the Hardwick tonalite, Wachusett tonalite, West Warren diorite, Walker Mountain orthogneiss, and Nichewaug diorite, and indicate transpression in the PZoT initiated after ca. 355 Ma. Monazite from Rangeley paragneisses and schists selected in the context of petrofabrics and syn-deformational mineral assemblages yield U-Th-Pb EPMA chemical ages that indicate dextral transpression occurred continuously from 355 to 315 Ma. Monazite chemical ages also indicate that sinistral lateral displacement in the west-bounding Mt. Dumplin high strain zone initiated ca. 325 Ma and lasted for roughly 45 m.y., ending around 280 Ma. The data for the Central Maine zone, Conant Brook shear zone, and Greenwich syncline support the idea of contemporaneous deformation across the compartmentalized zones of a transpressive system (355-315 Ma), while the ages for the Mt. Dumplin high strain zone indicate sinistral lateral displacement overlapped dextral transpression by about 10 m.y. but generally continued later in time (325-280 Ma).
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Schach, Régis. "Structure et propriétés mécaniques d'interfaces entre polymères fondus." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2006. http://tel.archives-ouvertes.fr/tel-00149339.
Повний текст джерелаАнотація:
Nous avons étudié les mécanismes qui sont à la base des phénomènes d'adhérence et d'autohésion des élastomères non réticulés.Nous avons déterminé les mécanismes de formation et de rupture d'interfaces entre deux polymères identiques de masse moléculaire et microstructure contrôlées. Nous avons ainsi développé une méthode de mesure de l'adhérence adaptée aux polymères fondus.
En utilisant cette méthode, nous avons comparé les mesures d'adhérence entre polymères immiscibles à l'équilibre thermodynamique et l'épaisseur de l'interface caractérisée par réflectivité des neutrons. Nous avons montré clairement que le paramètre de Flory pilote le degré d'adhérence entre deux polymères fondus immiscibles.
Cette corrélation entre interdiffusion et adhésion nous a finalement permis d'étudier la cinétique de diffusion mutuelle de ces polymères à partir des cinétiques de montée en adhésion et de prouver expérimentalement que cette cinétique est fortement ralentie par l'immiscibilité des polymères.
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Holmberg, Mika. "A study of the structure and dynamics of Saturn's inner plasma disk." Doctoral thesis, Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263278.
Повний текст джерелаАнотація:
This thesis presents a study of the inner plasma disk of Saturn. The results are derived from measurements by the instruments on board the Cassini spacecraft, mainly the Cassini Langmuir probe (LP), which has been in orbit around Saturn since 2004. One of the great discoveries of the Cassini spacecraft is that the Saturnian moon Enceladus, located at 3.95 Saturn radii (1 RS = 60,268 km), constantly expels water vapor and condensed water from ridges and troughs located in its south polar region. Impact ionization and photoionization of the water molecules, and subsequent transport, creates a plasma disk around the orbit of Enceladus. The plasma disk ion components are mainly hydrogen ions H+ and water group ions W+ (O+, OH+, H2O+, and H3O+). The Cassini LP is used to measure the properties of the plasma. A new method to derive ion density and ion velocity from Langmuir probe measurements has been developed. The estimated LP statistics are used to derive the extension of the plasma disk, which show plasma densities above ~20 cm-3 in between 2.7 and 8.8 RS. The densities also show a very variable plasma disk, varying with one order of magnitude at the inner part of the disk. We show that the density variation could partly be explained by a dayside/nightside asymmetry in both equatorial ion densities and azimuthal ion velocities. The asymmetry is suggested to be due to the particle orbits being shifted towards the Sun that in turn would cause the whole plasma disk to be shifted. We also investigate the ion loss processes of the inner plasma disk and conclude that loss by transport dominates loss by recombination in the entire region. However, loss by recombination is still important in the region closest to Enceladus (~±0.5 RS) where it differs with only a factor of two from ion transport loss.
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Boháčová, Marie. "Návrh sondy vířivých proudů a její aplikace pro zkoušení kompozitních leteckých konstrukcí." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-364595.
Повний текст джерелаАнотація:
This thesis deals with design of an eddy current transducer which enables non-destructive inspection of composite aircraft structures primarily carbon fiber reinforced plastic (CFRP) in areas of manufacture and maintenance. The design of the transducer is based on analytical-experimental approach and its electrical and mechanical parameters were optimized to ensure a good signal to noise ratio at the six composite samples. These samples contain artificial discontinuities in the form of various types of defects. These defects are simulating the various types of damage created in the aircraft structure, especially delamination or thickness changes of composite materials. The experimental measurements, data collection and non-destructive evaluation were performed during the period. The result of this work is functional eddy current probe, which is reliably able to detect some damage of the carbon composite structures to the depth of 3,9 mm.
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Giese, Christian [Verfasser], and Frank [Akademischer Betreuer] Stienkemeier. "Vibrational structure and dynamics of triatomic alkali molecules and RbHe exciplexes on helium nanodroplets investigated with femtosecond and picosecond pump-probe techniques = Vibrationsstruktur und Dynamik von dreiatomigen Alkalimolekülen und RbHe Exziplexen auf Helium Nanotröpfchen, untersucht mit Femtosekunden und Picosekunden Pump-Probe Techniken." Freiburg : Universität, 2012. http://d-nb.info/1123469385/34.
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Tutusaus, Lleixa Isaac. "Étude des composantes noires de l'univers avec la mission Euclid." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30212/document.
Повний текст джерелаАнотація:
Le modèle de concordance de la cosmologie, appelé ΛCDM, est un succès de la physique moderne, car il est capable de reproduire les principales observations cosmologiques avec une grande précision et très peu de paramètres libres. Cependant, il prédit l'existence de matière noire froide et d'énergie sombre sous la forme d'une constante cosmologique, qui n'ont pas encore été détectées directement. Par conséquent, il est important de considérer des modèles allant au-delà de ΛCDM et de les confronter aux observations, afin d'améliorer nos connaissances sur le secteur sombre de l'Univers. Le futur satellite Euclid, de l'Agence Spatiale Européenne, explorera un énorme volume de la structure à grande échelle de l'Univers en utilisant principalement le regroupement des galaxies et la distorsion de leurs images due aux lentilles gravitationnelles. Dans ce travail, nous caractérisons de façon quantitative les performances d'Euclid vis-à-vis des contraintes cosmologiques, à la fois pour le modèle de concordance, mais également pour des extensions phénoménologiques modifiant les deux composantes sombres de l'Univers. En particulier, nous accordons une attention particulière aux corrélations croisées entre les différentes sondes d'Euclid lors de leur combinaison et estimons de façon précise leur impact sur les résultats finaux. D'une part, nous montrons qu'Euclid fournira d'excellentes contraintes sur les modèles cosmologiques qui définitivement illuminera le secteur sombre. D'autre part, nous montrons que les corrélations croisées entre les sondes d'Euclid ne peuvent pas être négligées dans les analyses futures et, plus important encore, que l'ajout de ces corrélations améliore grandement les contraintes sur les paramètres cosmologiquesThe concordance model of cosmology, called ΛCDM, is a success, since it is able to reproduce the main cosmological observations with great accuracy and only few parameters. However, it predicts the existence of cold dark matter and dark energy in the form of a cosmological constant, which have not been directly detected yet. Therefore, it is important to consider models going beyond ΛCDM, and confront them against observations, in order to improve our knowledge on the dark sector of the Universe. The future Euclid satellite from the European Space Agency will probe a huge volume of the large-scale structure of the Universe using mainly the clustering of galaxies and the distortion of their images due to gravitational lensing. In this work, we quantitatively estimate the constraining power of the future Euclid data for the concordance model, as well as for some phenomenological extensions of it, modifying both dark components of the Universe. In particular, we pay special attention to the cross-correlations between the different Euclid probes when combining them, and assess their impact on the final results. On one hand, we show that Euclid will provide exquisite constraints on cosmological models that will definitely shed light on the dark sector. On the other hand, we show that cross-correlations between Euclid probes cannot be neglected in future analyses, and, more importantly, that the addition of these correlations largely improves the constraints on the cosmological parameters
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Wöhrmann, Hauke [Verfasser], and T. [Akademischer Betreuer] Müller. "First measurement of very forward jets with CASTOR in CMS to probe the structure of the proton down to x_Bjorken ≈ 10⁻⁶ / Hauke Wöhrmann ; Betreuer: T. Müller." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1141792486/34.
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Quintyn, Royston Samuel. "Applying Tandem Mass Spectrometry coupled with Ion Mobility to probe the Structure of Non-Covalent Protein Complexes and their Interactions with Ligands, Peptides and other Proteins." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437495530.
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