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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Överföring av NIR metod för kvantitativ analys mellan olika instrument / Transfer of a NIR Method for Quantitative Analysis between Different Instruments

Mado, George January 2019 (has links)
Detta examensarbete går ut på att överföra en metod- från ett Antaris NIR-instrument på AstraZeneca Macclesfield till ett Bomem 3600 NIR-instrument på AstraZeneca Gärtuna. Metoden används för att säkerställa att biprodukten form L ligger under specificerat gränsvärde för produkten. Kvantitativa NIR metoder är inte absoluta. De är prediktiva metoder som bygger på att man tar upp spektra för ett antal prover som man även analyserar med en referensmetod. Sedan använder man ett multivariat dataprogram som relaterar varje spektra till dess värde med referensmetoden med linjär regression. För att överföra en metod mellan två olika NIR-instrument behöver man matematiskt föra över de spektra som den multivariata modellen bygger på så att de matematiskt sett är analyserade på det instrumentet som man för över metoden till. De rådata som används till att bygga modellen är data från NIR instrumentet i Macclesfield och NIR-instrumentet i Gärtuna. Transformering av data utförs i Matlab med lokal centrering. De data som transformerats används sedan till att bygga modellen i SIMCA 14 som är en mjukvara för hantering av multivariata datamodeller. När modellens korrekthet kontrollerats skapas en metod i SenISS som använder sig av den nybyggda modellen för att prediktera Form L i produkten. Modellen är en PLS-modell med 2 komponenter som har de spektrala filtren SNV och andraderivatan. Dessa filter bidrar till signalkorrigering och minskar de individuella skillnaderna i spektrum. För att kontrollera modellens korrekthet har flera parametrar undersökts, dessa parametrar är: Linjäritet, riktighet, repeterbarhet och selektivitet. Linjäriteten kontrolleras med hjälp av ett valideringsset där modellen får prediktera halten Form L som sedan jämförs med det form L värdet som bestämts med referensmetoden. Regressions statistik beräknas för att undersöka att lutningen inkluderar värdet 1 och att interceptet inkluderar värdet 0 i ett 95%-igt konfidensintervall. Riktigheten kontrolleras genom att undersöka hur mycket prediktionerna avviker från referensmetoden värde. Den accepterade skillnaden är 20% RSD. Modellen har ett max RSD värde på 11,7%. Repeterbarheten kontrolleras genom att analysera 2 kapslar från 2 olika batcher 10 gånger var. Därefter beräknas den poolade standardavvikelsen och ett 95%-igt konfidensintervall. Den poolade standardavvikelsen är 0,55. Selektiviteten för modellen kontrolleras genom att analysera kapslar med annat innehåll, 5 kapslar med olika innehåll analyserades. Modellen ger höga värden på DModX (avståndet för varje observation till modellen) och/eller Hotelling’s T2 (avståndet från observationen till centrum av modellen) vilket innebär att de 5 analyserade kapslarna med annat innehåll avviker från modellen. / This diploma work treats the transferring of a method from an Antaris NIR-instrument at AstraZeneca Macclesfield to a Bomem 3600 NIR-instrument at AstraZeneca Gärtuna. The method is used to ensure that by-product form L is below the specified limit value for the product. Quantitative NIR methods are not absolute. They are predictive methods that are based on the inclusion of spectra for several samples that are also analyzed with a reference method. Then, a multivariate computer program is used that relates each spectra to its value with linear regression. To transfer a method between two different NIR-instruments, you need to mathematically transfer the spectra on which the multivariate model is based on, so that they are mathematically analyzed on the instrument that the method is transferred to. The raw data used to build the model is data from the NIR-instrument in Macclesfield and the NIR instrumentin Gärtuna. The transformation of data is performed in Matlab with local centering. The transformed data is then used to build the model in SIMCA 14 which is a software for managing multivariate data models. When the model's correctness is verified, a method is created in SenISS that uses the newly built model to predict Form L in the product. The model is a 2-component PLS model that has the SNV and second derivative spectral filters. These filters contribute to signal correction and reduce the individual differences in spectrum. To verify the correctness of the model, several parameters have been examined, these parameters are: linearity, accuracy, repeatability and selectivity. The linearity is verified by means of a validation set where the model can predict the content of Form L which is then compared with the Form L value determined with reference method. Regression statistics are calculated to verify that the slope includes the value 1 and that the intercept includes the value 0 in a 95% confidence interval. The accuracy is verified by examining how much the predictions deviates from the reference method. The accepted value is 20% RSD. The model has a maximum RSD value of 11.7%. The repeatability is verified by analyzing 2 capsules from 2 different batches 10 times each. Then the pooled standard deviation and a 95% confidence interval is calculated. The selectivity of the model is verified by analyzing capsules with other contents, 5 capsules with different contents is analyzed. The model gives high values of DModX (the distance for each observation to the model) and/or Hotelling's T2 (the distance from the observation to the center of the model) which means that the analyzed capsules with different content deviate from the model.
122

Nahinfrarot-Ultrakurzzeitspektroskopie an einwandigen Kohlenstoffnanoröhren in dotierten Dünnfilmen und Polymermatrizen / Near-infrared ultrafast spectroscopy on single-walled carbon nanotubes in doped thin films and polymer matrices

Kunkel, Pascal Gerhard January 2022 (has links) (PDF)
Nanoröhren, die auf dem Element Kohlenstoff basieren, besitzen ein großes Potential für ihre Anwendung als neuartige und nachhaltige Materialien im Bereich der Optoelektronik und weiteren zukunftsweisenden Technologiefeldern. Um jedoch hierfür genutzt werden zu können, ist ein tiefgreifendes Kenntnis über ihre außergewöhnlichen photophysikalischen Eigenschaften notwendig. Kohlenstoffnanoröhren sind als eindimensionale Halbleiter sehr vielseitige Materialien. Jedoch ist der Zusammenhang zwischen ihrer Eignung als Halbleiter und der dafür notwendigen Dotierung nur sehr unzureichend verstanden. Die Ziele der vorliegenden Dissertation waren deshalb, ein grundlegendes Verständnis der photophysikalischen Energietransferprozesse in Nanoröhren zu erlangen und den Einfluss von gezielten Dotierungen auf diese Prozesse im Hinblick auf ihre Eigenschaften als eindimensionale Halbleiter detailliert zu untersuchen. Die Grundlage für die Experimente bildeten verschiedene Filme aus einwandigen (6,5)-Kohlenstoffnanoröhren, die durch ein Polyfluoren-Copolymer in einer organischen Lösungsmittelumgebung isoliert wurden. Mit Hilfe der Ultrakurzzeitspektroskopie wurden die auf einer schnellen (ps-ns) Zeitskala ablaufenden photophysikalischen Prozesse an diesen Filmen unter verschiedenen Bedingungen untersucht und analysiert. In Kapitel 4 wurde der generelle Energietransfer der Kohlenstoffnanoröhren in Polymermatrizen im Detail studiert. Hierbei wurden durch Simulationen theoretische dreidimensionale Verteilungen von Kohlenstoffnanoröhren erzeugt und die nach einem Energietransfer vorliegenden Polarisationsanisotropien berechnet. Verschiedene Berechnungsansätze ergaben, dass die Nanorohrdichte ϱSWCNT für ein Massenüberschuss X der Matrix nahezu unabhängig von dem Röhrenvolumen war und durch ϱSWCNT = X−1 · 40 000 μm−1 angenähert werden konnte. Die Simulationen lieferten von der Röhrendichte abhängige Gaußverteilungen der zwischen den Nanoröhren vorliegenden Abständen. Aus den Verteilungen konnte weiterhin der Anteil an Röhren bestimmt werden, die für einen Energietransfer zur Verfügung stehen. Weitere Simulationen von Nanorohrverteilungen lieferten die Polarisationsanisotropie in Abhängigkeit von der Anzahl an durchgeführten Energietransferschritten. Die Ergebnisse aus den Simulationen wurden zur Interpretation der Ultrakurzzeitmessungen angewandt. Hierbei wurden durch die Variation der Polymermatrix die zwischen den Nanoröhren vorliegenden Abstände verändert und damit die Art und Intensität des Energietransfers kontrolliert. In Messungen der transienten Anisotropie zeigte sich, dass ein Exziton nach seiner Erzeugung zwei depolarisierende Energietransferschritte durchführte. Die Zerfallsdynamiken des Exzitons gaben auch klare Hinweise auf weitere nicht depolarisierende Energietransferprozesse, die durch parallel zueinander stehende Übergangsdipolmomente ermöglicht wurden. Eine Erklärung für dieses Verhalten lieferte die faserige Struktur der Filme, die sich in Aufnahmen durch das Elektronenmikroskop zeigte. Das Kapitel 5 beschäftigte sich mit dem Aufbau eines transienten Nahinfrarotspektrometers und den nötigen experimentellen Umbauten zur Messung der transienten Absorption für energiearme Signale im Spektralbereich unterhalb von 1.4 eV. Hierzu wurde die Weißlichterzeugung für die Verwendung von Calciumfluorid umgebaut. Das erzeugte Weißlicht wurde in das aufgebaute Prismenspektrometer eingekoppelt, um es weitestgehend linear auf einer Energieskala zu dispergieren. Auf diese Weise wurden energiearme Spektralkomponenten nicht auf unverhältnismäßig viele Pixel verteilt und konnten mit ausreichender Intensität detektiert werden. Die Lichtdetektion erfolgte mittels zweier Detektorzeilen aus Indiumgalliumarsenid, die das transiente Signal durch eine direkte Referenzierung stabilisierten. Weiterhin wurde in diesem Kapitel die Justage und die programmierte Ansteuerung des Systems detailliert beschrieben. Hierbei wurde auf die Justage der Einkopplung per Freistrahl, die Kalibrierung mittels Bandpassspektren sowie auf die Aufnahme von Weißlichtspektren und transienten Karten detailliert eingegangen. An Nanorohrdispersionen durchgeführten Testmessungen zeigten, dass das transiente Nahinfrarotspektrometer mit direkter Signalreferenzierung einwandfrei funktionierte und daher den beobachtbaren Spektralbereich auf den Bereich von Energien bis unterhalb von 1 eV erweiterte. Damit ermöglichte der Aufbau einen Zugang zu der Beobachtung größerer Nanorohrchiralitäten sowie zu der Untersuchung von energiearmen, spektralen Signaturen von Nanorohrdefekten. In Kapitel 6 wurde das transiente Nahinfrarotspektrometer genutzt, um das zeitabhängige Verhalten von redoxchemisch p-dotierten Nanoröhren zu charakterisieren und quantitativ zu beschreiben. Hierzu wurden die spektralen Eigenschaften von SWCNT-Dünnfilmen als Funktion eines steigenden Dotierungsgrades durch die Messungen der transienten und linearen Absorption studiert. In der linearen Absorption im Bereich von 0.9 - 2.5 eV vereinfachte sich das Spektrum mit ansteigender Dotierung stark und verlor vor allem im Bereich des ersten Subbandes deutlich an Oszillatorstärke. Bei starker Dotierung verschwanden die Signalbeiträge von X1 und der Phononenseitenbande. Weiterhin bleichte auch die bei mittleren Dotierungsgraden auftauchende Trionenabsorption aus und ging in die breite Absorptionsbande der H-Bande über. Das Erscheinen und Verschwinden der trionischen sowie exzitonischen Absorption war ebenfalls in der transienten Absorption durch zeitgleich auftretende/verschwindende Photobleichsignale zu erkennen. Sowohl der Zerfall des exzitonischen PB-Signals wie auch des Trions beschleunigte sich mit einer steigenden Dotierung. Die Zerfallszeit des Exzitons im undotierten Film betrug 6.87 ps und verkürzte sich auf 0.732 ps bei höheren Dotierungsgraden. Die Zerfallszeit des Photobleichens des Trions reduzierte sich von 2.02 ps auf 0.440 ps. Auffallend war hierbei, dass das Trion im Vergleich zu dem Exziton exponentiell zerfiel und damit auf eine Lokalisierung dieses Zustandes hinweist. Bei höheren Dotierungsmittelkonzentrationen tauchte in der transienten Absorption ein neuer Signalbeitrag auf. Die Existenz dieses Signals konnte auf die H-Bande zurückgeführt werden und könnte auf einer Verschiebung des linearen Absorptionsspektrums aufgrund einer Renormalisierung der Bandlücke oder der Sättigung von Ladungsträgern beruhen. Das Signal zeigte eine klare Abhängigkeit vom Dotierungsgrad des Nanorohrfilmes. So wies es eine hypsochrome Verschiebung auf, wurde spektral breiter und seine Zerfallsdauer reduzierte sich von 1.62 ps auf 0.520 ps mit steigendem Dotierungsgrad. / Carbon based nanotubes possess a tremendous potential as novel and sustainable materials in application areas such as optoelectronics and other prospective technologies. However to fully exploit it, an in-depth understanding of their unique photophysical features is essential. Carbon nanotubes are one-dimensional semiconductors and are therefore very versatile materials. However, the relationship between their suitability as semiconductors and the required doping for this purpose, is only scarcely understood. The main aim of this thesis was to provide a fundamental understanding of photophysical events such as energy transfer processes in those nanotubes and to elucidate the impact of controlled doping on those events with respect to their one-dimensional semiconductor properties. The experiments performed were based on films made from single-walled (6,5)-carbon nanotubes isolated by a polyfluorene copolymer in organic solvent. By applying ultrafast laser spectroscopy one was able to monitor and analyse photophysical events occurring on a short (ps-ns) time scale in these films under varying conditions. Chapter 4 presented an detailed investigation of the general energy transfer occurring in carbon nanotubes embedded into polymeric matrices. For this purpose, simulations were carried out to generate theoretical, three-dimensional distributions of the nanotubes to calculate the corresponding polarization anisotropy upon energy transfer. Varying computational approaches clearly showed that the nanotube density ϱSWCNT for a mass excess X of the matrix was nearly completely independent of the tube volume: The relationship could be approximated with ϱSWCNT = X−1 · 40 000 μm−1. The simulations provided Gaussian distributions of the intertube distances, which were shown to be dependent on the density of the nanotubes in the films. The distributions even provided the fraction of tubes available for energy transfer to occur. Further simulations of nanotube distributions were carried out to establish the relationship between the polarization anisotropy and the number of energy transfer steps taken. These results were then used for a detailed analysis of the measured ultrafast photo-events in those nanotubes. In the corresponding experiments the polymer matrix was varied to alter the intertube distances between the embedded nanotubes in a controlled manner and as a result also control the intensity of the possible energy transfer. The observed transient anisotropy clearly indicated that an exciton was carrying out two depolarizing steps of energy transfer upon its generation. The exciton decay dynamics indicated the presence of addition non-depolarizing energy transfer processes due to the presence of parallel dipole moments in those events. This behavior was caused by the fibrous nature of the films, as clearly seen by electron microscopy. Chapter 5 presented the experimental setup of the transient near-infrared spectrometer, built and used for this PhD, including the necessary experimental modifications to measure transient absorption for low-energy signals in the spectral range below 1.4 eV. For this purpose a calcium fluoride based white light had to be generated. The generated white light was then coupled into a specifically constructed prism spectrometer to disperse the light on a mostly linear energy scale. By using this principle, low-energy spectral components were not distributed over a disproportionate number of pixels and could therefore be detected with sufficient intensity. The corresponding detection of light was achieved using two lines of indium gallium arsenide detectors. This setup stabilized the transient signal through direct referencing. Furthermore, this chapter also described in detail the required experimental adjustment and control program, which was written for this purpose. In addition, the adjustment of the coupling of the light into the system via free beam, the calibration via bandpass spectra and the acquisition of white light spectra and transient maps were discussed in-detail. Test measurements carried out on dispersions of nanotubes, confirmed the design and flawless functioning of the transient nearinfrared spectrometer with direct signal referencing, extending the observable spectral range to energies below 1 eV. The setup even enabled the study of nanotube samples with low-energy spectral signatures due to nanotube defects and it can even be used to investigate nanotubes with large chiralities. In chapter 6, the time-dependent photophysical behavior of p-doped nanotubes (by redoxchemical means) was discussed, based on detailed investigations and quantitative analysis of results obtained by the transient near-infrared spectrometer presented in chapter 5. In particular, the spectral properties of thin films of SWCNT were studied as a function of increasing levels of p-doping by monitoring their corresponding transient and linear absorption behavior. In the range of 0.9 - 2.5 eV the linear absorption spectrum simplified with increasing doping levels. The oscillator strength decreased significantly, especially in the area of the first sub band. In samples doped at high levels, the signal contributions from X1 and the phonon sidebands disappeared. In addition, the absorption of trions, which appeared at medium doping levels, also bleached and merged into the broad absorption band of the H-band. The appearance and disappearance of trionic and excitonic absorption was also observable in the transient absorption by simultaneously appearance/disappearance of photobleaching signals. Both, the decay of the excitonic and the trionic PB signal accelerated with increasing doping levels. The excitonic decay time of 6.87 ps in the pristine film became only 0.732 ps in nanotube films doped at high levels. The decay time for the trionic photo-bleaching also dropped from 2.02 ps to 0.440 ps. Interestingly, the trionic decay occurred exponentially in contrast to the excitonic decay; a behavior which clearly indicated the localization of this state. At higher concentrations of dopant, a new signal contribution emerged in the transient absorption spectra. The existence of this signal could be attributed to the H-band and could be caused by a shift of the linear absorption spectrum due to a band gap renormalization or by saturation of the charge carriers. The signal exhibited a clear dependence on the doping levels of the nanotube film. It also showed a hypsochromic shift and became spectrally broadened. The decay time also dropped from 1.62 ps to 0.520 ps for samples doped at higher levels.
123

Tracing Characteristics of Two Water Hole Features with Multiproxy Analysis : Using Soil Chemistry, Archaeobotany and Entomology / Multiproxyanalys för att studera och karaktärisera brunnsanläggningar : Genom att använda markkemi, arkeobotanik och entmologi

Kantak, Johanna January 2023 (has links)
En omfattande multiproxyanalys har utförts på provtagningar från två vattenhål belägna i Skåneregionen i Sverige. Denna mångsidiga analys involverade flera aspekter, inklusive markkemi, entomologi, mikrofossiler och makrofossiler. Resultaten från markkemianalysen avslöjade betydande skillnader mellan de två vattenhålen. Vattenhål 1 uppvisade en högre halt av organiskt material, vilket tyder på högre glödförluster och högre värden av maximal magnetisk susceptibilitet (MS550) och totalfosfat (CitPOI). För att ytterligare karakterisera egenskaperna hos vattenhålen användes även analyserna infrarödspektroskopi (NiR) och röntgenfluorescens (XRF).   Vattenhål 2 visade tecken på att ha fyllts med bosättningsavfall från platsen. Detta stöddes av markkemiresultaten som visade en lägre halt av organiskt material samt närvaron av antropogena material, såsom förkolnade frön, träkol, bränd lera, ben och keramikfragment.   Makrofossilanalysen avslöjade intressanta fynd. I vattenhål 1 hade växter som etternässla (Urtica urens) och kråkklöver (Comarum palustre) deponerats, tillsammans med enstaka exemplar av Thrips major Uzel. I kontrast bestod de förkolnade fröna från vattenhål 2 huvudsakligen av ogräs, inklusive svinmålla (Chenopodium album) och nattskatta (Solanum nigrum). Det fanns även spår av sädeskorn som korn (Hordeum vulgare), samt oidentifierade fragment av sädeskorn. Resultaten från makrofossilanalysen indikerade att materialet från vattenhål 1 härstammar troligtvis från forntida mänskliga aktiviteter, som odling.   Mikrofossilanalysen visade att det inte fanns några kiselalger (diatoméer) i något av vattenhålen. Sammantaget antyder resultaten från multiproxyanalysen att vattenhål 1 hade genomgått minst tre olika faser i sin historia, medan vattenhål 2 hade fyllts med jord och material från en bosättningsliknande plats, vilket gjorde det svårt att entydigt tolka själva vattenhålets historia och funktion.
124

Smart coatings for energy saving buildings

Rosati, Andrea 24 October 2022 (has links)
The present thesis is devoted to synthesis, through the environmentally friendly citrate sol-gel route, of YIn0.9O3 −ZnO near infrared reflective based pigments, having different chromophore elements (Mn, Cu, Fe), with the aim to add in binder and obtaining cool coatings. A “cool” coating for roofing consists of paint (or glaze) containing color pigments, which do not absorb the infrared portion of the solar spectrum. Cool coatings applied over buildings surface provide an effective solution for passive cooling of building indoors and influencing local outdoor microclimate, mitigating urban heat islands effect (UHIE). The primary purpose is to produce pigments according to an environmentally friendly route, using non-toxic raw materials, as well as short times and low temperatures for synthesis, and without residual waste. The resulting pigments must have high reflectance in the near-infrared so that they can be used in the field of cold paints. To realize the corresponding coatings, pigments were dispersed in two different binders (standard PMMA and industrial binder). For the most interesting pigments, in terms of NIR reflectance, other property, was decided to explore, which define these NIR reflective pigments as smart pigments for building application: the photocatalytic ability.
125

Organic open-shell materials for optoelectronic and magnetic applications

Sabuj, Md Abdus 25 November 2020 (has links)
Organic open-shell materials, which are responsive to external stimuli; such as light, electronic field, magnetic field, etc., are subject to intensive studies in recent years for their potential application in the field of organic solar cells, semiconductors, supercapacitors, singletission, non-linear optical (NLO), spintronics, and magnetic materials. As the materials with an open-shell diradical (two unpaired electrons) or polyradical (multiple unpaired electrons) character have a significant promise for next-generation optoelectronics, magnetic, and spintronic devices, it is of paramount importance to design suitable materials with tunable electronic properties. Also, a proper understanding of the molecular topology with electro-magnetic properties and correlate with quantum functionalities can move forward the field of organic photovoltaics and optoelectronics. Here, we show that controlling the radical character based on the different molecular scaffolds can lead to materials from closed-shell (all electrons are paired) low-spin (singlet state) to intermediate open-shell (multi)radical state to high-spin (triplet state) ground-state in the pristine form. In this regard, several organic donoreptor (D-A) polymeric and small molecular systems are designed and characterized. We find that the diradical character is ubiquitous in the narrow bandgap organic materials. Based on this design rule, we have reported open-shell dyes for dye-sensitized solar cells (DSCs), which show significantly red-shifted absorption in the NIR than the closed-shell counterpart dyes. Our work on the alternating D-A polymers indicate stabilization of the high-spin triplet ground-state in the neutral form, not reported for D-A type polymers. A significant delocalization of the unpaired electrons provides thermodynamic stability of the polymer, which when used in supercapacitors, a best-in-class energy density, and a long cycle life are observed. Also, we find that the spin topology can be modulated by careful selection of molecular scaffold in the extended pi-conjugated D-A polymers. Furthermore, our study on D-A macrocycles indicates that the antiferromagnetic (AFM) couplings between the unpaired electrons can be tuned by thiophene pi-spacer, developing a record polyradical character in the macromolecular systems.
126

Assessing Corn Quality And Transformation During Nixtamalization: A Physico-Chemical Approach

Lucius, Ruth A. 12 February 2009 (has links)
No description available.
127

Magnetite Oxidation in Aqueous Systems

Templeton, John Andrew 15 July 2008 (has links)
Magnetite, an iron oxide, is a possible candidate for in situ remediation of contaminated groundwater systems due to its oxidation/reduction potential for reduction of contaminants such as carbon tetrachloride. Little characterization and analysis has been done to describe the kinetics of magnetite transformation during oxidation. This work focuses on monitoring the concentrations of magnetite and one of its oxidation transformation products, maghemite, by the use of UV-Vis-NIR spectroscopy. As oxidation proceeded at a constant specific temperature, the concentration of magnetite decreases, which was indicated by a decrease in absorption in the NIR-region of the spectrum. As magnetite concentrations decreased, the concentration of maghemite increased, which was indicated by an increase in absorption in the UV-region. The temperature at which the suspensions of magnetite and maghemite were measured was of great importance for complete understanding of the magnetite transformation as seen by UV-Vis-NIR spectroscopy analysis. Higher measurement temperatures produced higher absorptivities of FeII-FeIII electron hopping transitions, while decreasing the absorptivity of FeIII-FeIII in the NIR and UV-regions respectively. Lower temperatures produced the opposite effects on the iron oxides' transitions. Higher temperature increased the rate of oxidation. / Master of Science
128

Design and synthesis of donor-acceptor-donor xanthene-based near infrared I and shortwave infrared (SWIR) dyes for biological imaging

Rathnamalala, Chathuranga 12 May 2023 (has links) (PDF)
Small molecule organic dyes with absorption and emission in the near infrared region (NIR) attracted much attention for various applications such as dye sensitized solar cells, fluorescent guided surgery, stimuli responsive bioimaging and photodynamic therapy. Dyes with high absorption and emission in the NIR region are beneficial for stimuli responsive bioimaging due to the deeper penetration of NIR light, less cell damage, high resolution, and low background autofluorescence from biomolecules. Of the many small molecule dyes, xanthene-based dyes exhibit outstanding photophysical properties and good stimuli response for use in bioimaging applications. However, absorption and emission of the xanthene dyes lie in the visible region, which limit their applications in cellular imaging. Many of the NIR dyes have very poor fluorescence; consequently, an alternative approach to fluorescent imaging is photoacoustic imaging that uses sound waves to generate pictures of deep tissues. In this dissertation, we discuss the utility of xanthene based NIR dyes as photoacoustic imaging contrast agents for multiplex imaging and deep tissue nitric oxide sensing in the drug-induced liver injury. Chapter I discuss the fundamentals of fluorescence and photoacoustic imaging, background of the xanthene dyes and other fluorescent dyes, and the design strategies to develop NIR xanthene-based dyes. Chapter II is based on our approach to the design and synthesis of NIR xanthene-based dyes by C-H bond functionalization, with the first example being Rhodindolizine, which absorb and emits in NIR II or short-wave infrared (SWIR) region. In chapter III, we describe the design and synthesis of thienylpiperidine xanthene-based NIR and shortwave-infrared (SWIR) dyes for the photoacoustic imaging. One dye in particular (XanthCR-880) boasts a strong PA signal at 880 nm with good biological compatibility and photostability, yields multiplexed imaging with an aza-BODIPY reference dye, and is detected at a depth of 4 cm. In chapter IV, we report a series of SWIR dyes based on a dibenzazepine donor conjugated to thiophene (SCR-1, SCR-4), thienothiophene (SCR-2, SCR-5), and bithiophene (SCR-3, SCR-6). We leverage the fact that SCR-1 undergoes a bathochromic shift when aggregated to develop a ratiometric nanoparticle for nitric oxide (NO) (rNP-NO). rNP-NO was used to successfully perform in vivo studies to visualize pathological levels of nitric oxide in a drug-induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Chapter V describes another series of xanthene-based dyes with a thiophene ᴫ spacer and several different donors. UV-Vis absorption studies were performed after converting the dyes to the opened form with trifluoracetic acid. These novel XanthCR-TD dyes exhibit absorption maxima in NIR I region from 700 - 900 nm.
129

Plasticidade de árvores de Eucalyptus grandis no contexto das mudanças climáticas: interação do déficit hídrico e da fertilização no crescimento e qualidade do lenho das árvores / Plasticity of Eucalyptus grandis trees in the contexto of climate change: interaction of drought and fertilization on wood growth and quality

Franco, Mariana Pires 19 April 2018 (has links)
A plasticidade do Eucalyptus às mudanças no clima merece destaque, principalmente pelo fato da maioria dos povoamentos florestais implantados no Brasil serem, em geral, estabelecidos em regiões de baixa fertilidade, pobres em potássio (K) e submetidos a longos períodos de déficit hídrico. A expansão das plantações pode ser prejudicada pelas mudanças climáticas, com a alteração da frequência e intensidade da precipitação. Desta forma, o presente trabalho tem como objetivo avaliar o efeito da interação do déficit hídrico e da fertilização com K e sódio (Na) no crescimento e qualidade do lenho de árvores de E. grandis sob o contexto das mudanças climáticas. Em experimento do tipo split-plot instalado em junho de 2010, foram selecionadas 54 árvores de eucalipto com cinco anos submetidas a dois regimes hídricos (100% e 63%) e três fertilizantes (K, Na e controle). Realizou-se a amostragem do lenho, coletando-se seis discos nas posições base, DAP, 25, 50, 75 e 100% da altura total. Avaliou-se as propriedades físicas (densidade aparente por densitometria de raios x e predição da densidade básica por NIR), propriedades anatômicas (fibras e vasos) e química (predição do teor de extrativos totais pela aquisição da imagem HI-NIR), de acordo com os tratamentos. Para a predição dos extrativos, propôs-se a predição direta e a transferência de calibração entre equipamentos NIR e HI-NIR. A transferência foi baseada em uma coleção de base de calibração completa medida nos dois aparelhos. Comparou-se quatro modelos de transferência de calibração (Update, Repfile, PDS e TOP). A eficácia dos modelos foi testada em um grupo de amostras teste (1/3 das amostras totais). Os resultados mostram que em todas as propriedades do lenho houve efeito significativo dos tratamentos; a densidade aparente é menor nas árvores fertilizadas com K e Na e sem exclusão parcial de chuvas. A predição da densidade básica apresentou resultado satisfatório com RMSECV igual a 0,022 g/cm³. As fibras são maiores nas árvores fertilizadas com K e apresentam maior espessura de parede nas árvores controle, ambas na condição de exclusão parcial de chuvas. Os vasos e a largura dos anéis de crescimento sofreram influência, principalmente, da exclusão de chuvas. A predição direta do teor de extrativos totais foi eficácia, mostrando resultados semelhantes com a literatura para valores de extrativos de eucalipto preditos e observados. O tratamento K sem exclusão parcial de chuvas apresentou o menor valor médio predito de extrativos totais (3,90%). O melhor modelo de transferência de calibração foi o TOP, com SEP de 1,53%, SECV de 1,41% e R² de 0,88. Conclui-se que a interação do déficit hídrico e da fertilização influenciou as propriedades do lenho das árvores de E. grandis e as análises realizadas permitem traçar estratégias mais adequadas para dar subsídio à expansão de povoamentos florestais brasileiros em áreas sujeitas a longos períodos de seca. / The plasticity of the Eucalyptus to changes in the climate deserves to be highlighted, mainly because most of the forests implanted in Brazil are generally established in regions of low fertility, poor in potassium (K) and subjected to long periods of drought. Expansion of plantations can be hindered by climate change, with changes in the frequency and intensity of precipitation. The objective of this work is to evaluate the interaction of drought and fertilization with K and sodium (Na) on the growth and quality of E. grandis trees in the context of climate change. In a split-plot experiment installed in June 2010, 54 Eucalyptus trees with five years submitted to two water regimes (100% and 63%) and three fertilizers (K, Na and control) were selected. Sampling was carried out by collecting six discs at the base positions, DBH, 25, 50, 75 and 100% of the total height. The physical properties (apparent density by x-ray densitometry and basic density prediction by NIR), anatomical properties (fibers and vessels) and chemistry (prediction of total extractive content by HI-NIR image acquisition) were evaluated according to the treatments. For the prediction of extractives, the direct prediction and calibration transfer between NIR and HI-NIR equipment was proposed. The transfer was based on a complete calibration base collection measured on both devices. Four calibration transfer models (Update, Repfile, PDS and TOP) were compared. The efficacy of the models was tested in test set samples (1/3 of the total samples). The results show that in all the properties of the wood there was significant effect of the treatments; the apparent density is lower in the trees fertilized with K and Na and without partial throughfall exclusion. The prediction of the basic density presented satisfactory results with RMSECV of 0.022 g/cm³. The fibers are larger in the trees fertilized with K and present a greater thickness of wall in the control trees, both in partial throughfall exclusion. The vessels and the width of the growth rings were influenced, mainly, by partial throughfall exclusion. The direct prediction of the total extractive content was efficacy, showing similar results with the literature for values of predicted and observed Eucalyptus extractives. The K treatment without partial rainfall exclusion had the lowest predicted mean value of total extractives (3.90%). The best calibration transfer model was the TOP, with SEP of 1.53%, SECV of 1.41% and R² of 0.88. The conclusion of this work is that the interaction of water deficit and fertilization influences the wood properties of E. grandis trees and the analyzes carried out allow to draw up more adequate strategies to subsidize the expansion of Brazilian plantation forests in areas subject to long periods of drought.
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Obtenção e caracterização espectroscópica de vidros tungstênio fosfato dopados com íons terras-raras / Obtainment and spectroscopic characterization of tungsten phosphate glasses doped with rare earth ions

Guidini, Priscila França 19 October 2018 (has links)
Vidros dopados com íons terras-raras trivalentes TR3+, são materiais importantes devido a suas potenciais aplicações tecnológicas como em dispositivos luminescentes e lasers de estado sólido. Os TR3+ possuem níveis de energia eletrônicos que permitem obter emissões desde o ultravioleta até o infravermelho próximo. A classe de vidros tungstênio fosfatos tem sido amplamente estudada devido as suas propriedades incomuns aos vidros fosfato clássicos como, por exemplo, alta estabilidade térmica contra devitrificarão, absorção óptica não linear e efeitos fotocrômicos mediante irradiação. Neste trabalho, foram estudados vidros tungstênio fosfato dopados com os íons Nd3+, Tb3+ e co-dopados com os íons Er3+ e Yb3+, no sistema composicional 90NaPO3-10WO3 + x%Nd2O3 (x = 0,25; 0,5; 1; 3 e 5% em peso em excesso) 90NaPO3 – 10WO3 + y%TbF3 (y = 0,1; 0,5; 1; 3 e 5 em peso em excesso) (90-z-k)NaPO3 – 10WO3 + z%Er2O3 + k%Yb2O3 (z = 0,25; 0,5; e 1 mol%; k = 0 e 2 mol%). As amostras foram obtidas pelo método convencional de fusão e resfriamento e foram caracterizadas por absorção UV-VIS-NIR, fotoluminescência (emissão e excitação), e tempos de vida de estado excitado. Para as amostras dopadas com Nd3+ foram observadas emissões intensas em 1060 nm, os tempos de vida do nível emissor 4F3/2 foram medidos e a eficiência quântica do sistema foi estimada. As amostras dopadas com Tb3+ apresentaram o pico de emissão de maior intensidade em 542 nm, porém para os vidros com baixa concentração de íon dopante, duas transições com intensidades relativas da mesma ordem da transição do verde, correspondentes a emissões em 415 nm e 435 nm, foram observadas e o tempo de vida para estado emissor 5D4 também foi medido. Os vidros co-dopados com Er3+/Yb3+ apresentaram emissões intensas em 522 nm, 545 nm e 658 nm em um processo de conversão ascendente de energia (upconversion) que envolve dois fótons. Os tempos de vida do estado emissor 4I13/2 do Er3+ dessa amostra também foram mensurados. / Glasses and glass-ceramics doped with trivalent earth-rare ions TR3+, are important materials due to their potential technological applications, such as in luminescent devices and solid-state lasers. These ions have electronic energy levels that allow emissions from ultraviolet to infrared. The tungsten phosphate glass class has been extensively studied due to its unusual properties when compared to the classical phosphate glasses, such as high thermal stability against devitrification, nonlinear optical absorption, photochromic effects under visible irradiation, and efficient emission properties of earth-rare ions. In this work, tungsten phosphate glasses doped with Nd3+ and Tb3+ ions. and co-doped with Er3+ and Yb3+ ions, were studied in the compositional system 90NaPO3-10WO3 + x%Nd2O3 (x = 0.25; 0.5; 1; 3 e 5% by weight in excess) 90NaPO3 – 10WO3 + y%TbF3 (y = 0.1; 0.5; 1; 3 e 5 by weight in excess) (90-z-k)NaPO3 – 10WO3 + z%Er2O3 + k%Yb2O3 (z = 0.25; 0.5; e 1 mol%; k = 0 e 2 mol%). The samples were obtained by the conventional melt quenching technique and were characterized by UV-VIS-NIR absorption, photoluminescence (emission and excitation), and excited state lifetime values. For samples doped with Nd3+ intense emissions were observed at 1060 nm, the lifetimes of the 4F3/2 emitting level were measured and the quantum efficiency of the system was estimated. The Tb3+ doped samples presented the highest intensity emission peak at 542 nm, but for the glasses with low dopant ion concentration, two transitions with relative intensities of the same order of the green transition, corresponding to emissions at 415 nm and 435 nm were detected. The lifetime value of the 5D4 emitting state was also measured. The Er3+/Yb3+ co-doped glasses exhibited intense emission at 522 nm, 545 nm and 658 nm in an upconversion process involving two photons, the lifetime of the emitting state 4I13/2 of Er3+ were also measured for these samples.

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