Dissertations / Theses on the topic 'Light sensitive'
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1
Thompson, Andrew. "Light Sensitive." CSUSB ScholarWorks, 2015. https://scholarworks.lib.csusb.edu/etd/245.
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I am an excremental artist. I do not mean an artist who works with feces or is interested in manure but one whose artwork is expelled through the results of process. As a photographer, I am not as interested in indexing a location, a person or a moment as I am dissolving the structure of photography through the manipulation of photographic materials. I typically photograph landscapes that catch my attention for a myriad of reasons. The commonality between these images is anonymity of place. Hints of location are always present but never accentuated, instead their purpose is akin to a forging slug: raw blank material from which my artwork will be created. My photographic slugs are then entered into various processing systems that I have devised over the years. Common processing techniques that I incorporate include hand and machine stitching, chemically altering photographic paper and the integration of open-source electronics. These and other processes are mixed, matched and blended to form the corpus of my work.
The body of my work is not complete without my head, heart and hands. My intellectual interests are constantly feeding the physical processes described above. I have an extended engagement with photography’s rich history along with a critical commitment to philosophy. My intuition is permitted to work in concert with my intellect despite stark contrasts between the two. My intellect looks for structures and speaks in logical thought while my intuition arrives in waves of unarticulated emotions and ‘gut feelings’. The heart’s language is often more difficult to translate than intellectual headband but both are equally valuable in my process. Finally, my hands play a vital role in creating my art. They transcribe the conversation between the head and the heart and physically complete the processes defined prior.
My artwork is not conceived and the built into a structure, instead it is a result of the passing through a system. I consume copious amounts of stimuli (intellectually, visually, emotionally) and digest it through my creative process and the result is my artwork.
2
Nguty, T. A. "Light sensitive optical fibres." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360457.
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Dcona, Martin. "Drug Delivery Strategies Using Light Sensitive Molecules." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/445.
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Cancer remains one of the most dreaded diseases due to inevitable suffering and possible fatality. Only cardiac disease has caused more deaths than cancer. Present day cancer treatment involves radiation, surgery or chemotherapy. In chemotherapy, an anti-tumoral drug is used to treat the tumor either by killing or stalling the growth of the tumor cells. In certain types of cancer, for e.g. metastatic breast cancer, the first line of therapy is often chemotherapy. But the inability of current clinically approved drugs to selectively target tumor cells, ultimately results in side effects. To reduce these side effects, prodrug therapies have been developed. A prodrug is defined as a drug molecule inactivated by a temporary cap or carrier, subsequently removed by an external intra or extracellular stimulus. Several prodrug strategies such as ADEPT (Antibody–Directed Enzyme Prodrug Therapy) have been tested in clinical trials but have thus far met with limited success. In the wake of these limitations, development of photo-activatable prodrugs may be particularly desirable for minimizing the adverse side effects associated with current cancer chemotherapeutics. Photodynamic therapy (PDT) is a light dependent tumor treatment modality that has existed for many years. PDT involves a photosensitizer which is administered to the patient and later activated using the light of wavelengths between 650-800 nm. The activated photosensitizer creates singlet oxygen, which acts as cytotoxic agent to the tumor cells. But this approach has several drawbacks including slow uptake of the photosensitizer by the tumor cells and the dependence on molecular oxygen that is not always present at even moderate levels in the tumor tissues. To address these limitations of PDT, we developed a new prodrug concept called ‘Photocaged Permeability’ in our first project, and demonstrated drug delivery using this approach. The basis of this concept is that, by attaching a hydrophilic molecule to the drug via a photosensitive linker, the permeability of the drug could be restrained. But the drug could be released at the site of the tumor after irradiating with UV light. To achieve this goal, we designed and synthesized a photosensitive drug conjugate that was comprised of doxorubicin attached to a negatively charged, cell impermeable molecule, EDANS (5-((2-Aminoethyl) amino) naphthalein-1-sulfonic acid) via a photosensitive nitroveratryl linker. Later, we performed MTT (cell viability) assays using esophageal adenocarcinoma (JH-EsoAd1) cells to determine the efficiency of our drug conjugate to induce cell death. As expected our drug conjugate was able to induce cell death, but only in presence of light. But in the dark, the cells remained unaffected. Also, we did several control studies to substantiate the fact that the cell death was actually due to drug release but not due to light or other entities. Further, we performed FACS (Fluorescence Assisted Cell Sorting) and confocal assays to show that in dark, the drug conjugate did not permeate cells. But upon irradiation with UV light, the drug was released from the conjugate, permeated the cells and induced cell death. A weakness of the above mentioned approach is that the drug is “decaged” or photo-released from the conjugates only under UV light; which cannot be translated to physiological conditions. This is because the UV light cannot penetrate deeper than 5 mm into the human skin. As a result, tumor cells that are deeply embedded in the human body cannot be treated using these approaches. To address this problem, Near Infrared (NIR) light could be used as it penetrates deeper than UV. Recently, several groups have reported using Upconverting Nanoparticles (UCNP) for the purpose of drug activation. The basis of this phenomenon is that the incidence of NIR light on these particles initiates multi-photon processes, eventually emitting UV/VIS wavelengths. The advantage of the NIR is that it deeply penetrates into the human skin. In our latest project, we have designed a drug conjugate that would be attached to UCNPs. We envision that after grafting the drug conjugate onto the nanoparticles and irradiating it with NIR drug release will occur as a result of upconversion. The above two systems describes novel methodologies for controlled release of the drug. To further improve the efficacy of the drug action, we designed new photosensitive systems based on the concept of targeted drug delivery. Targeted drug delivery is a treatment methodology in which the modified chemotherapeutic drug with higher tumor affinity could be concentrated in the tumor tissues. In certain cases, the receptors of tumor cells are targeted for the purpose of therapy. Receptors are cell surface proteins that are expressed on their plasma membrane. A select few of them such as Folic Acid Receptor (FAR) and PSMA (Prostate Specific Membrane Antigen) are overexpressed in malignant cells. In our new designs, we attached folic acid and urea based (DUPA) ligand, which were previously reported to bind to FAR and PSMA receptors respectively. Cell studies are currently underway to determine the specificity of these drug conjugates in targeting tumor cells. Once we demonstrate the above drug delivery strategies in vitro and later in vivo, we will have established novel drug delivery systems that could potentially be applied towards chemotherapeutic treatment.
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Rodríguez, Amigo Beatriz. "Light-sensitive nanocarriers for drug delivery in photodynamic therapy." Doctoral thesis, Universitat Ramon Llull, 2018. http://hdl.handle.net/10803/462210.
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Aquesta tesi aprofundeix en l’estudi de nanotransportadors com a sistemes de vehiculització i en alguns casos, alliberació de fotosensibilitzadors emprats en teràpia fotodinàmica. S’han fet servir dos nanotransportadors de naturalesa diferent: proteïnes i liposomes.
En primer lloc s’ha investigat els complexos formats entre la hipericina i les proteïnes apomioglobina i β-lactoglobulina. S’han estudiat les característiques fisicoquímiques i fotofísiques, avaluant l’activitat antimicrobiana en front a bacteris gram-positius i gram-negatius. En ambdues matrius proteiques el fotosensibilitzador es troba majoritàriament en forma monomèrica, preservant les seves propietats fotofísiques i formant un complex estable. En el cas de la β-lactoglobulina s’estudia a més, la formació del complex amb l’adició d’un 20% de DMSO com a co-solvent, fet que millora les propietats fotofísiques en detriment de la capacitat antimicrobiana. Ambdós complexos proteics son efectius contra bacteris gram-positius però no contra gram-negatius. Per altra banda, es demostra que la hipericina incorporada a la cavitat de l’apomioglobina pot ser utilitzada en microscòpia de super-resolució STED. Amb aquesta tècnica es pot monitoritzar els llocs d’unió del fotosensibilitzador a la membrana dels bacteris. Així mateix, s’estudia l’ús de la β-lactoglobulina com a portador dual d’hipericina i àcid retinoic. En aquest últim sistema multi-component s’avaluen les propietats fotofísiques per a verificar la formació i estabilitat del complex.
En segon lloc, es desenvolupa un nanovehicle per la seva aplicació en teràpia combinada en el qual s’incorporen fàrmacs quimioterapèutics convencionals amb agents fotosensibilitzants, per superar resistències i millorar l’eficàcia dels tractaments individuals. Amb aquest objectiu, s’han dissenyat i estudiat dues formulacions liposomals diferents, ambdues amb el mateix fotosensibilitzador però encapsulant diferents agents quimioterapèutics. Es preparen formulacions bimodals on s’incorporen els dos agents al mateix vehicle i els seus homòlegs unimodals, amb la incorporació única d’un dels dos agents. S’han avaluat les característiques fisicoquímiques, fotofísiques i fotobiològiques de les suspensions bimodals i unimodals. La lozalització subcel·lular demostra que cada principi actiu es localitza a orgànuls diferents desencadenant rutes de senyalització cel·lular diferents, eludint els possibles mecanismes de resistència. El tractament in vitro en cèl·lules cancerígenes amb aquests sistemes tenen un efecte prometedor, ja que com a mínim presenten un comportament additiu respecte els tractaments individuals. Finalment, s’ha avaluat el potencial de la vehiculització activa mitjançant la unió covalent d’un anticòs monoclonal a la superfície, el que millora lleugerament els resultats per una de les dues formulacions.Esta tesis profundiza en el estudio de nanotransportadores como sistema de vehiculización y en algunos casos, liberación de fotosensibilizadores empleados en terapia fotodinámica. Se emplean dos nanotransportadores de naturaleza distinta: proteínas y liposomas. En primer lugar se han investigado los complejos formados entre hipericina y las proteínas apomioglobina y β-lactoglobulina. Se han estudiado las características fisicoquímicas y fotofísicas, evaluando la actividad antimicrobiana frente bacterias gram-positivas y gram-negativas. En ambas matrices proteicas el fotosensibilizador se encuentra mayoritariamente en forma monomérica, preservando sus propiedades fotofísicas y formando un complejo estable. En el caso de la β-lactoglobulina se estudia además, la formación del complejo con la adición del 20% de DMSO como co-solvente, lo que mejora las propiedades físicas pero sorprendentemente, empeora la capacidad antimicrobiana. Ambos complejos proteicos son efectivos contra bacterias gram-positivas, pero no contra gram-negativas. Además, se demuestra que la hipericina en la cavidad de la apomioglobina es capaz de realizar microscopía de super-resolución STED, mediante la cual se puede monitorizar los sitios de unión a las bacterias. Asimismo, se ha estudiado la β-lactoglobulina como portador dual de hipericina y ácido retinoico. En este último sistema multi-componente se evalúan las propiedades fotofísicas para verificar la formación y estabilidad del complejo. En segundo lugar, se desarrolla un nanovehículo para su uso en terapia combinada en el que se incorpora fármacos quimioterapéuticos convencionales con agentes fotosensibilizantes, para superar las resistencias y mejorar la eficacia de los tratamientos individuales. Con este objetivo, se han diseñado y estudiado dos formulaciones liposomales diferentes, ambas con el mismo fotosensibilizador, pero con diferentes agentes quimioterapéuticos. Se preparan las formulaciones bimodales con ambos agentes en el mismo vehículo además de sus homólogos unimodales, con la incorporación única de uno de los dos agentes. Se han evaluado las características fisicoquímicas, fotofísicas y fotobiológicas de las suspensiones bimodales y unimodales. La localización subcelular demuestra que cada principio activo se localiza en orgánulos diferentes desencadenando rutas de señalización celular diferentes, eludiendo los posibles mecanismos de resistencia. El tratamiento in vitro en células cancerígenas de estos sistemas tiene un efecto prometedor siendo al menos aditivo en comparación con los tratamientos individuales. Finalmente, se ha evaluado el potencial de la vehiculización activa mediante la unión covalente de un anticuerpo monoclonal en la superficie, lo que lleva a resultados ligeramente superiores para una de las dos formulaciones.
This thesis reports the study of nanocarriers as drug delivery systems for photosensitisers in photodynamic therapy. Proteins and liposomes are the two nanovehicles of different nature used for this purpose. Beginning with the proteins, the complexes formed between hypericin and the proteins apomyoglobin and β-lactoglobulin have been explored. The physicochemical and photophysical properties have been studied, as also assessing their photoantibacterial activity against Gram-positive and Gram-negative bacteria. In both protein scaffolds the photosensitiser is found mainly in monomeric form, preserving its fluorescence and singlet oxygen photosensitising properties and yielding a stable complex. In the case of β-lactoglobulin, the complex formation has also been tested with the addition of a 20% DMSO as a co-solvent, which improves the photophysical properties but surprisingly, worsens its antimicrobial activity. Both protein complexes are effective against Gram-positive but not against Gram-negative bacteria. Moreover, it has been proved that hypericin, inside the apomyoglobin cavity, can perform STED microscopy through which its localization in bacteria can be monitored. Additionally, the suitability of β-lactoglobulin as a dual carrier for hypericin and acid retinoic has also been exploited. In this last multi-component system, the photophysical properties have been evaluated to confirm the formation and complex stability. Secondly, a nanocarrier for its use in combined therapy has been developed, in which conventional chemotherapeutic drugs are combined with photosensitising agents to overcome resistance and improve the effectiveness of the individual treatments. For this purpose, two different liposome formulations have been designed and studied with a common photosensitiser but different anti tumour drugs. The bimodal formulations with both agents entrapped and their unimodal counterparts, having each drug loaded in separate liposomes, have been evaluated. The physicochemical, photophysical and photobiological properties of bimodal and unimodal suspensions have been studied. The subcellular localization shows different organelle accumulation by each agent, triggering different key signals transduction pathways, eluding the cellular resistance mechanisms. The treatment in vitro of these multi-component liposomes with cancer cells has a promising effect, since at least an additive outcome is observed when compared with the individual treatments. Finally, we have explored the potential of active targeting strategies by covalently linking a monoclonal antibody to the surface, leading to slightly greater outcomes for one of the liposomal formulations.
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Mello, Olivia L. "Quantum state reconstruction and tomography using phase-sensitive light detection." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92703.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-70).
In this thesis we present an optical and electronic setup that is capable of performing coherent state tomography. We fully characterize it in order to verify whether or not it will be capable to perform non-demolition homodyne detection of squeezed light in a high-finesse cavity QED setup with an ensemble of Cesium atoms coupled to the cavity. After quantifying sources of noise, the photodiode efficiency, we perform a series of measurements of low photon number coherent states and compare them against the standard quantum limit. We discuss a variety of technical challenges encountered in such systems and some methods to overcome them. Lastly, we test the apparatus' ability to do quantum state tomography and quantum state reconstruction by reconstructing the density matrix and Wigner functions for low photon-number coherent states.
by Olivia L. Mello.
S.B.
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Erkmen, Baris Ibrahim 1980. "Phase-sensitive light : coherence theory and applications to optical imaging." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44209.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 197-201).
Spontaneous parametric downconversion (SPDC) can produce pairs of entangled photons, i.e., a stream of biphotons. SPDC has been utilized in a number of optical imaging applications, such as optical coherence tomography, ghost imaging, holography and lithography, to obtain performance that cannot be realized with standard optical sources. However, a debate continues as to whether the improved imaging characteristics of such systems should be attributed to the entanglement property of the photon pairs. This thesis sets out to unify--and generalize--classical and quantum imaging within the framework of Gaussian-state light fields, which encompasses thermal light--the source used in conventional imagers--and biphoton-state light as special instances. Within this framework, we are able to provide a complete understanding of the boundary between classical and quantum behavior in optical coherence tomography (OCT), ghost imaging and two-photon imaging. Furthermore, we show that almost all characteristics of biphoton-state imagers are due to phase-sensitive cross correlations, and hence are obtainable with classical phase-sensitive sources.
by Baris I. Erkmen.
Ph.D.
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Klinger, Daniel [Verfasser]. "Light-sensitive polymeric nanoparticles based on photo-cleavable chromophores / Daniel Klinger." Mainz : Universitätsbibliothek Mainz, 2012. http://d-nb.info/1018615008/34.
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Jacobs, William P. V. "Performance of Pressure Sensitive Adhesive Tapes In Wood Light-Frame Shear Walls." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32795.
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The performance of connections and full-scale shear walls constructed with acrylic foam pressure sensitive adhesive (PSA) tape is the focus of this thesis. The objectives of this study were first to investigate the bonding characteristics of adhesive tape to wood substrates and then to expand this investigation to cover adhesive-based shear walls subjected to high wind and seismic loadings. A total of 287 monotonic connection tests and 23 reversed cyclic wall tests were performed to achieve these objectives. Connection tests were performed in accordance with ASTM D 1761-88 (2000), and walls were tested using the CUREE (Consortium of Universities for Earthquake Engineering) general displacement-based protocol.
Variables investigated within the main study were the following: the use of OSB versus plywood sheathing, the effect of priming and surface sanding on adhesion, and the comparison of connections involving mechanical fasteners with those that utilized only adhesive tape or a combination of the two. It was found that an application pressure of 207 kPa (30 psi) or greater was needed to form a sound bond between the acrylic foam adhesive tape and a wood substrate. Properly bonded OSB and plywood connections provided fairly ductile failure modes. Full-scale walls constructed with adhesive tape performed similarly to traditional wall configurations, while walls constructed with a combination of adhesive tape and mechanical fasteners provided significant gains in strength and toughness. The results of this study serve to provide a foundation for expanding the engineering uses of acrylic foam adhesive tape for structural applications.
Master of Science
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Krupa, Susanne. "Is the nap zone controlled by a light-sensitive circadian arousal process?" Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/29056.
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This study attempts to identify the mechanism of the so-called afternoon nap zone. More specifically, it investigates a recent proposal that the afternoon nap zone represents the point in time after morning awakening when process-S has increased to a sufficiently high level to facilitate sleep onset, while at the same time an SCN-controlled circadian arousal process has not yet risen high enough to reverse this increased sleepiness.
Eight normal male subjects aged 20--30 years, were monitored on two separate occasions under low ambient light (150 lux). Night sleep hours were maintained at 23:00--06:00h. PSG monitoring included EEG (C3-A2, O2-A1), right EOG-M1, left EOG-M2, submental EMG and core body temperature recorded continuously by a combination of the Oxford Medilog 9000 8-channel ambulatory recorder and the Minilogger temperature monitoring system. Following a baseline 24-hour day, bright light stimulation (10,000 lux) was given on two consecutive days either in the evening (20:00--22:00h) or morning (06:00--08:00h) in counter-balanced fashion with a 30 day washout periods between. Other than during a period of bright light stimulation, the level of daytime arousal was assessed every 60 min by quantified EEG spectral power followed by a 10 min duration simple reaction time test.
In the baseline condition both the performance and Q-EEG variables confirmed the presence of a transitory afternoon nap zone as indexed by the timing of poorest performance and of greatest spectral power in a number of Q-EEG measures. Evening bright light treatment phase delayed these nap zone measures. Conversely, morning bright light phase advanced these measures.
The finding that the timing of poorest performance and of the Q-EEG determined nap zone can be phase delayed by evening light and phase advanced by morning light supports the hypothesis tested, as well as supporting the existence of an SCN-dependent circadian arousal system in humans similar to that described by Edgar et al. (1993) in sub-human primates.
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Benouaich, Abigail. "Bring Light to Gaza. An exploration of solar and ecologically-sensitive light programs for the Deir al-Balah refugee camp." Thesis, KTH, Ljusdesign, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280044.
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In Gaza, daily blackouts have lasted for over eleven years. Until recently, Palestinian families have received only four hours of power each day. Since Israel’s withdrawal from the region in 2005, the political discourse around the Right of Return has forced refugees to live in terrible conditions and darkness. The fear was that any transformation of the camps will bring about an integration of the refugee community with the local environment and thus any improvements to Gaza’s infrastructure and housing was seen as a direct erosion of the Right of Return. Can bringing light to Gaza transcend this boundary of temporality and restore hope to this impoverished community? With recent solar lighting ideas emerging to help solve Gaza’s energy shortage by solar energy companies such as SunBox and LittleSun, I plan to develop a solar urban lighting project for Gaza’s smallest refugee camp - Deir al-Balah (DEB) - to help improve security at night for residents and provide the community with opportunities to socialise in public common areas. In response to an ‘Improvement Plan’ conducted by the United Nations Relief and Works Agency (UNRWA) in 2017, which identifies DEB camp’s limited access to electricity and street lighting, I’d like to explore how a solar and ecologically-sensitive lighting programs can improve Gazan’s daily lives, by bringing clean, reliable and affordable energy access.
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Ehrenhofer, Adrian, Alice Mieting, Sascha Pfeil, Johannes Mersch, Chokri Cherif, Gerald Gerlach, and Thomas Wallmersperger. "An automatically rainproofing bike helmet through light-sensitive hydrogel meshes: Design, modeling and experiments." SPIE, 2020. https://tud.qucosa.de/id/qucosa%3A74218.
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For everyday cycling, one needs to carry rainproof clothing just for the case of unexpected downpours. In the present research, we present a concept for a helmet which is automatically rainproof when the rain starts. When the sun comes out, the helmet is breathable again even before it completely dries up. This functionality is provided by active hydrogel meshes. Hydrogel meshes offer great advantages due to their ability to change the aperture size with swelling and deswelling. In our current work, we present the design and modeling steps for hydrogel-layered active meshes which use (i) swelling and deswelling in hydrated state and (ii) swelling starting from the dry state. The main goal is to close the air openings of a bicycle helmet when rain starts as an automatic rainproofing. This can be achieved through the swelling of the hydrogel pNiPAAM-co-chlorophyllin in the meshes, which leads to closing when hydrated. At the same time, the light-sensitive behavior leads to opening of the apertures under direct sun exposure, i.e. when the sun appears again after the rain. We present the steps of modeling and design using the Normalized Extended Temperature-Expansion-Model (NETEM) to perform simulations in Abaqus. The model is capable of describing both the swelling of the hydrogel under light stimulus and the volume change due to hydration. It is based on the analogy between free swelling and thermal expansion and defined for nonlinear displacements. We also discuss the fabrication process of hydrogel-layered fibers and challenges in their application and simulation. As a proof of concept for hydrogel-layered meshes, we show preliminary experimental results of a poly(acrylamide)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAm/PAMPS) hydrogel with semi-interpenetrated network (SIPN) structure and its swelling capacities on a mesh. Starting from the active hydrogel meshes as presented in the current work, the next step can be smart textiles that harness the power of hydrogels: the adaptation to combinations of stimuli - like humidity, temperature and brightness - that define environments.
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Gestrich, Julia [Verfasser]. "Analysis of PDF expressing and light sensitive circadian pacemaker neurons in the cockroach Rhyparobia maderae / Julia Gestrich." Kassel : Universitätsbibliothek Kassel, 2018. http://d-nb.info/1174700858/34.
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Leung, Yiu Tak. "Studies of light-induced dynamic changes in [Ca²⁺]i and photocurrent in isolated ultraviolet-sensitive zebrafish cones." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613941.
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Shi, Feimo. "A THERMO- AND LIGHT- SENSITIVE STAR-LIKE COPOLYMER: DESIGN, SYNTHESIS, AND POTENTIAL APPLICATION FOR DRUG DELIVERY SYSTEM." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1428072959.
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Tonndorf, Robert, Martin Kirsten, Rolf-Dieter Hund, and Chokri Cherif. "Designing UV/VIS/NIR-sensitive shape memory filament yarns." Sage, 2015. https://tud.qucosa.de/id/qucosa%3A35400.
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A novel laser light-sensitive yarn based on a thermoplastic polyester–urethane (TPU) has been prepared and analyzed. Since the thermosensitive shape memory polymer yarn (SMP yarn) has been functionalized using nanoscale heat sources exhibiting light-induced heat generation, the yarn is capable of an optically triggered shape memory effect (SME). For this purpose gold nanorods (GNR) have been employed. In addition to the incorporation of GNR into the yarn, a coating of GNR on the yarn is also proposed, applied by a semi-continuous layer-by-layer (LBL) technique. The SME of the functionalized yarns can be triggered either thermally or optically and has a strain recovery of almost 100%. The light-induced SME is triggered by a low-powered laser (808 nm, 2 W for a GNR-incorporated and 1W for a GNRcoated TPU yarn). A reference yarn without GNR showed no significant effect. An adaptive structure featuring a SMPyarn backed shape memory effect has been proposed and demonstrated.
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Hickey, Doron. "Optogenetic gene therapy for vision restoration : light-sensitive proteins, viral vectors and bipolar cell adaptation to a diseased state." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:820a45d5-60db-4c01-808a-8a3720c48f2c.
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Inherited retinal dystrophies are a heterogeneous group of retinal diseases that often lead to blindness. The diverse range of causative gene mutations poses great challenges to developing therapies to improve the vision of affected people. One technique being investigated is optogenetics for vision restoration, a technique that aims to deliver light-sensitising molecules to the affected retina. This research project provides data on a range of variables that need to be optimised in order to successfully restore vision using an optogenetic gene therapy approach. Fifteen wild type, chimeric and fusion constructs based on human opsins were compared by in vitro and in vivo tests to select the optimal light-sensitising construct. Of these, wild type rhodopsin, melanopsin and melanopsin-Ga subunit fusion constructs show the most promise for future studies. For delivery of the light-sensitising construct, the adeno-associated virus (AAV) serotype AAV2/2(7m8) was shown to perform best compared to two other AAV serotypes when tested in degenerate mouse eyes and macaque and human retinal explants. The importance of the delivery route to the eye, the use of a targeted versus non-targeted approach and the AAV vector concentration were all tested in in vivo experiments. In addition to testing such variables, the gene expression changes in target retinal bipolar cells in late-stage retinal degeneration were examined by microarray analysis of bipolar cell enriched samples isolated by fluorescence-activated cell sorting. Genes important for G protein signalling were generally expressed at a similar level in the degenerate state, while genes associated with oxidative stress and metabolism were differentially expressed. Collectively, these data will inform the choice of construct, delivery method and target cell in future research into optogenetic strategies for vision restoration.
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Marchant, Maïté. "Modélisation multi-échelles des systèmes nanophotoniques à base de matériaux intelligents." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22449.
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Beaucoup d’applications en ingénierie demandent l’utilisation de matériaux intelligents qui peuvent se déformer en réponse à un stimulus extérieur. C’est dans ce contexte, que s’est posé ce projet de recherche. Bénéficiant d’un environnement pluridisciplinaire, grâce à l’association de deux axes de l'Institut Pascal : l’axe MMS (Mécanique, Matériaux et Structures) et l’axe PHOTON (Axe Photonique, Ondes, Nanomatériaux), cette thèse s’intègre parfaitement dans l’action transversale "Matériaux et Modélisations multi-échelles" du laboratoire. La première partie de ce travail s'appuie sur un système expérimental mis au point par une équipe américaine [Chang_10] qui permet la mesure sans contact du pH d'une solution en exploitant les caractéristiques photoniques du système. Ce système est composé d'un réseau d'hydrogel fixé sur un substrat rigide. Un modèle numérique est développé dans le but de simuler le fonctionnement de l'ensemble et d'optimiser le réseau d'hydrogel en vue d'applications dans le domaine médical. La seconde partie de ce travail concerne le développement d'une théorie sur le comportement mécanique de polymères sensibles à la lumière. L'objectif est d'établir une relation liant la déformation du matériau à l’intensité lumineuse. Les résultats obtenus sont comparés avec les résultats expérimentaux issus de la littérature. L'influence des interactions entre les molécules d'azobenzènes sur la déformation du matériau est étudiéeMany engineering applications involve stimuli-responsive materials that can change their shape under the action of an external stimulus. It is in this context that this project takes place. Thanks to a multidisciplinary environment with the association of two lines of research of the Institut Pascal: the Mechanical area (Mechanic, Materials and structure) and the Photonic area (Nanostructures and Nanophotonics), this PhD perfectly fits with the “Materials and multi-scale Modeling” transversal action of the laboratory. The first part of this work relies on an experimental system developed by an American team [Chang_10] which allows to measure the pH of a solution without contact, making use of its photonic characteristics. This system is composed of a hydrogel network fixed on a rigid substract. A numerical model is developed in order to simulate its behavior and optimize the hydrogel network with a view to applications in the medical domain. The second part of this PhD is related to the development of a theory on the mechanical behavior of photo-sensitive polymers. The aim is to establish a link between the material deformation and the light intensity. The obtained results are compared to experimental ones from literature. The interaction influence of the azobenzenes molecules on the material strain is studied
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Müller, Rouven [Verfasser], and C. [Akademischer Betreuer] Barner-Kowollik. "Spatially resolved immobilization of metallopolymers – Spiropyrans for light sensitive metal complexes and STED-inspired laser lithography / Rouven Müller ; Betreuer: C. Barner-Kowollik." Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1197138900/34.
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Fromme, Ulrich Verfasser], Christoph F. [Akademischer Betreuer] Schmidt, Andreas [Gutachter] Neef, Tobias [Gutachter] [Moser, Florentin [Gutachter] Wörgötter, Stefan [Gutachter] Klumpp, and Marc [Gutachter] Timme. "Investigation of voltage- and light-sensitive ion channels / Ulrich Fromme. Betreuer: Christoph F. Schmidt. Gutachter: Andreas Neef ; Tobias Moser ; Florentin Wörgötter ; Stefan Klumpp ; Marc Timme." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1111100934/34.
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ESTEBAN, NYDIA MARGARITA HABRAN. "VISIBLE LIGHT SENSITIVE MESOPOROUS NANOHYBRID, PREPARED FROM LEPIDOCROCITE-LIKE FERRITITANATE COUPLED TO A CHARGE TRANSFER COMPLEX AND ITS APPLICATION IN PHOTOCATALYTIC CONVERSION OF A POLLUTANT GAS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33940@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O foco do presente estudo é desenvolvimento de uma heteroestrutura de dois semicondutores com capacidade de reduzir a taxa de recombinação elétron/buraco mediante uma intensa separação de carga, e ao mesmo tempo sendo sensível ao espectro de luz visível. A separação de carga estaria sendo alcançada por meio da injeção de elétrons livres dentro da banda de condução (BC) do TiO2 na forma de anatásio, provenientes do orbital molecular mais alto ocupado (HOMO) da acetilacetona (Acac), ligada às partículas de anatásio, seguida da sua injeção dentro dos orbitais d desocupados do Fe3+ localizados dentro da banda de energia proibida das nanofolhas de ferrititanatos. Ao mesmo tempo a absorção da luz visível poderia ser assegurada através das nanofolhas de ferrititanatos, considerando-se a interação dos níveis energéticos do Fe3+ com a luz e as bandas de valência e condução, bem como pela formação de complexo de transferência de carga (CTC), entre as nanopartículas de anatásio e Acac. Os nanohíbridos mesoporosos (as heteroestruturas) são produzidos pelas diferentes rotas de junção de nanofolhas de ferrititanato, obtidas da areia mineral ilmenítica e posteriormente esfoliadas, com nanopartículas de TiO2 modificadas com acetilacetona, estes útlimos formando CTC. As técnicas de caraterização empregadas tais como adsorção-dessorção de N2, espectroscopia de emissão de fotoluminescência (PL) e espectroscopia de refletância difusa (DRS), entre outras, confirmaram a formação das heteroestruturas mesoporosas sensíveis à luz visível e com forte mecanismo de separação de cargas. A fotodegradação do gás poluente NO no espectro de luz-visível por meio de vários nanohíbridos mesoporosos (fotocatalisadores) mostrou-se bem sucedida, exibindo uma eficiência até 7 vezes superior em comparação à atividade do material fotocatalítico padrão TiO2 (P-25 da Degussa).
This work focues on the development of a heterostructure composed by two semiconductors, capable to decrease the electron/hole recombination rate through a robust charge separation, and at the same time, this nanohybrid is sensitive to visible light spectrum. The charge separation is achieved by the injection of free electrons within the conduction band (BC) of TiO2 in anatase form, which come from the highest-occupied-molecular-orbital (HOMO) of acetylacetone (Acac), linked to the anatase nanoparticles, followed by the injection into unoccupied Fe3+ d-orbital within band-gap energy of the ferrititanate nanosheets. Additionally, the absorption of visible light could be assured by ferrititanate nanosheets, considering the interaction of the energy levels of Fe3+ with visible light and the valence and conduction bands, as well as, the formation of the charge transfer complex (CTC), between the anatase nanoparticles and Acac. The mesoporous nanohybrids (called also as heterostructures) were produced by different routes of junction of two components: i) ferrititanate nanosheets, which were synthesized from ilmenite mineral sands, and then they were exfoliated into single layers and ii) TiO2 nanoparticles, modified with Acac, which formed the CTC. The characterization techniques, such as N2 adsorption-desorption, photoluminescence emission spectroscopy (PL) and diffuse reflectance spectroscopy (DRS), and so on, confirmed the formation of the mesoporous heterostructures sensitive to visible light and with a robust mechanism of charge separation. The photodegradation of NO pollutant gas within the visible light spectrum through several mesoporous nanohybrids (photocatalysts) demonstrated being well succeeded, exhibiting an efficiency more than seven times higher than the activity benchmark TiO2 (Degussa P-25) photocatalyst.
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Gonçalves, Myra Adam de Oliveira. "A fotografia sem câmera : revelações de especificidades da fotografia através do quimigrama." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10746.
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Esta dissertação foca um processo de criação de imagens fotográficas a partir de manipulações químicas feitas sobre superfícies fotossensíveis, diretamente sobre o papel ou negativo, sem utilizar para isso o aparato tecnológico – a câmera. A partir dessa abordagem, a dissertação analisa os limites daquilo que conhecemos como fotografia. A pesquisa convergiu para a investigação das possibilidades fotográficas inerentes às superfícies sensíveis e fotossensíveis, às soluções fotoquímicas e para o cruzamento dessas possibilidades fotográficas com outras linguagens artísticas. O trabalho confrontou a fotografia com suas especificidades e buscou desvendar os domínios da fotograficidade, que se configurou como um lugar apropriado para vasculhar as certezas e incertezas do que é a fotografia. As reflexões teóricas foram instituídas pelo trabalho plástico.This dissertation aims at a photographic images creation process from chemistry manipulations made over light sensitive surfaces, directly on the paper or negative, without the camera. From this point of view the dissertation analyses the limits of which we know as photograph. The research converged to an investigation of the inherent photographic possibilities to sensitive and light sensitive surfaces, to photochemical solutions and to an approaching of these photographic possibilities to other kinds of artistic languages. The creation process faced photograph and its unique features and, by dealing with them, tried to reveal the photographs unique characteristics, which showed a specific place to search the certainties and uncertainties of what photography is. The theoretic reflections were established by the artistic work.
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Mun, Kyu-Shik. "Monitoring Cell Behaviors on Variety of Micropatterns Created with Biodegradable Polymer." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1457426363.
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Peter, Emanuel Verfasser], Stephan [Akademischer Betreuer] Bäurle, Bernhard [Akademischer Betreuer] [Dick, and Friederike [Akademischer Betreuer] Schmid. "Development and application of new computer simulation techniques to describe the multi-scale relaxation dynamics of light-sensitive protein systems / Emanuel Peter. Betreuer: Stephan Bäurle ; Bernhard Dick ; Friederike Schmid." Regensburg : Universitätsbibliothek Regensburg, 2012. http://d-nb.info/1037020731/34.
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Toresson, Elin, and Gunnarson Anton. "Att underlätta orientering i mörka utställningsrum : En studie i museimiljö." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Byggnadsteknik och belysningsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-40371.
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Denna studie är ett examensarbete som utförs som en del av utbildningen Produktutveckling med inriktning ljusdesign under våren 2018 vid Jönköpings Tekniska Högskola. Studien gjordes för att undersöka hur belysning kan underlätta orientering i mörka utställningsrum, utan att negativt påverka den upplevda atmosfären samtidigt som utställningsföremålen är i fokus för besökarna. Målet är att kunskapen som samlas in från denna studie ska kunna användas för att skapa ett underlag vid planering av belysning på Marinmuseet i Karlskrona. Studien genomfördes först genom en förstudie där problem och förutsättningar för att orientera sig i mörka utställningsrum undersöktes genom en enkät och en observationsstudie på Vasamuseet och Marinmuseet. En huvudstudie genomfördes sedan på Marinmuseet där. Lou Michels teori Visual Objective Theory prövades som ett verktyg för att underlätta orientering i mörka utställningsrum. Huvudstudien genomfördes under två dagar med hjälp av en enkätundersökning och en observationsstudie. Resultatet från enkätstudien antydde att upplevelsen av atmosfär kan påverkas av Visual Objective Theory, dock finns det inget som pekar mot att den påverkas negativt. I övrigt gav enkätstudien inga starka implikationer till en slutsats. Observationsstudien var mer tydlig och gav underlag för att Visual Objective Theory är ett bra verktyg för att påverka besökarnas rörelsemönster.This study is a thesis performed as a part of the education Product development aligned with Lighting design during the spring 2018 at Jönköping School of Engineering. This study was made to research how lighting can facilitate orientation in dark exhibition rooms, without negatively affecting the experienced atmosphere while at the same time maintaining the exhibition subjects in focus for the visitors. The goal is that the knowledge collected from this study can be used as a basis when planning lighting at the Marine Museum in Karlskrona. The study was first performed through a prestudy where problems and conditions for orienting in dark exhibition rooms was tested with a survey and an observational study at the Vasamuseet and Marinmuseet. A main study was then performed at Marinmuseet, where Lou Michels theory Visual Objective Theory was tested as a tool to facilitate orientation in dark exhibition rooms. The main study was performed during two days, containing a questionnaire and an observational study. The results from the survey implied that the experience of atmosphere can be affected by Visual Objective Theory, however there is nothing implying that the experience is negatively affected. Other than that the results from the survey gave no strong implications for a conclusion. The observational study was clearer and gave support for Visual Objective Theory being a good tool for affecting the visitors movement patterns.
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Van, Wyk Frans-Pieter. "Simutaneous real-time object recognition and pose estimation for artificial systems operating in dynamic environments." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/33323.
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Recent advances in technology have increased awareness of the necessity for automated systems in
people’s everyday lives. Artificial systems are more frequently being introduced into environments
previously thought to be too perilous for humans to operate in. Some robots can be used to extract
potentially hazardous materials from sites inaccessible to humans, while others are being developed
to aid humans with laborious tasks.
A crucial aspect of all artificial systems is the manner in which they interact with their immediate surroundings.
Developing such a deceivingly simply aspect has proven to be significantly challenging, as
it not only entails the methods through which the system perceives its environment, but also its ability
to perform critical tasks. These undertakings often involve the coordination of numerous subsystems,
each performing its own complex duty. To complicate matters further, it is nowadays becoming
increasingly important for these artificial systems to be able to perform their tasks in real-time.
The task of object recognition is typically described as the process of retrieving the object in a database
that is most similar to an unknown, or query, object. Pose estimation, on the other hand, involves
estimating the position and orientation of an object in three-dimensional space, as seen from an observer’s
viewpoint. These two tasks are regarded as vital to many computer vision techniques and regularly serve as input to more complex perception algorithms.
An approach is presented which regards the object recognition and pose estimation procedures as
mutually dependent. The core idea is that dissimilar objects might appear similar when observed
from certain viewpoints. A feature-based conceptualisation, which makes use of a database, is implemented
and used to perform simultaneous object recognition and pose estimation. The design
incorporates data compression techniques, originally suggested by the image-processing community,
to facilitate fast processing of large databases.
System performance is quantified primarily on object recognition, pose estimation and execution time
characteristics. These aspects are investigated under ideal conditions by exploiting three-dimensional
models of relevant objects. The performance of the system is also analysed for practical scenarios
by acquiring input data from a structured light implementation, which resembles that obtained from
many commercial range scanners.
Practical experiments indicate that the system was capable of performing simultaneous object recognition
and pose estimation in approximately 230 ms once a novel object has been sensed. An average
object recognition accuracy of approximately 73% was achieved. The pose estimation results were
reasonable but prompted further research. The results are comparable to what has been achieved using
other suggested approaches such as Viewpoint Feature Histograms and Spin Images.Dissertation (MEng)--University of Pretoria, 2013.
gm2014
Electrical, Electronic and Computer Engineering
unrestricted
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Barth, Andreas. "Frequency sensitive moment tensor inversion for light to moderate magnitude earthquakes in eastern Africa and derivation of the regional stress field Frequenzabhängige Momententensorinversion für schwache bis mittelstarke Erdbeben im östlichen Afrika und Ableitung des regionalen Spannungsfeldes /." [S.l. : s.n.], 2007. http://swbplus.bsz-bw.de/bsz262419157abs.pdf.
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Woodhouse, Joyce. "Etude d'une protéine fluorescente photo-commutable par cristallographie résolue en temps en utilisant les lasers à électrons libres." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY026/document.
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Les protéines fluorescentes photocommutables (RSFPs) ont la propriété de passer d’un état fluorescent à un état non-fluorescent en réponse à la lumière. Cette propriété en fait des outils de marquage pour la microscopie de super-résolution (ou nanoscopie). Le mécanisme de photocommutation implique l’isomérisation du chromophore ainsi qu’un changement d’état de protonation de ce dernier. Le mécanisme a été très étudié par différentes approches de spectroscopie et de simulation mais reste encore mal compris, l’ordre séquentiel des évènements est notamment encore débattu. Certains de ces évènements de la photocommutation se déroulent à des échelles de temps très courtes, ce qui rend difficile l’étude structurale par cristallographie des rayons X à l’aide des sources synchrotron actuelles dont la résolution temporelle est encore limitée. Les lasers à électrons libres (XFELs) sont une nouvelle source de rayons X produisant des impulsions suffisamment courtes pour permettre l’étude structurale des intermédiaires précoces ou à courte durée de vie qui se forment ou cours de la photocommutation, et suffisamment brillantes pour permettre la collecte de données cristallographiques sur des cristaux de tailles nano- et micrométrique. L’utilisation de ce nouveau genre d’instrument a permis l’émergence de la cristallographie sérielle, une nouvelle approche de la cristallographie des rayons X. Cette approche a depuis été adaptée aux lignes synchrotrons.Le travail présenté ici se focalise sur l’étude de rsEGFP2, une protéine fluorescente photocommutable de la famille de la GFP. Il y est décrit la mise au point d’un protocole de microcristallisation permettant l’obtention d’échantillons en vue d’une expérience de cristallographie résolue en temps au XFEL. Un mécanisme de photocommutation y est proposé à travers le résultat de deux expériences sur les deux XFELs actuellement opérationnels, à des échelles de temps différentes, dévoilant un chromophore « twisté » à l’état excité ainsi qu’un état cis protoné de ce dernier. La caractérisation structurale des variants de rsEGFP2 par cristallographie d’oscillation « classique » combinée à la découverte fortuite d’une conformation alternée du chromophore dans l’état non-fluorescent, issue d’expérience de cristallographie sérielle, apporte un complément d’explication des propriétés photophysiques de la protéineReversibly switchable fluorescent proteins (RSFPs) are able to reversibly toggle between a fluorescent on-state and a non-fluorescent off-state under visible light irradiation. This property makes them a suitable marker used in super-resolution microscopy (or nanoscopy). The photo-switching mechanism involves isomerisation of the chromophore and a change of its protonation state. This mechanism has been well studied but remains poorly understood. The structural nature and the sequential order of atomistic events are still under debate. Some of them take place on the ultra-fast time scale and make structural investigation by X-ray crystallography impossible using current synchrotron radiation sources whose temporal resolution they offer is limited. X-ray free electron lasers (XFELs) are a new kind of X-ray source producing femtosecond pulses that allow structural investigation of ultra-fast intermediates during photoswitching. They are also so bright that crystallographic data collection from micro- and nanometer-sized crystals became possible. The bright and short XFEL pulses required a new methodology to be developed, the so-called serial crystallography methodology. This method is now being adapted to synchrotron radiation facilities.Here is presented a time-resolved crystallography study of the reversibly switchable green fluorescent protein 2 (rsEGFP2). A microcrystallization protocol is described allowing the preparation of suitable samples in large amounts for time-resolved serial crystallography experiments. A photoswitching mechanism of rsEGFP2 is proposed based on crystallographic results obtained from data collected at the two XFEL facilities currently fully operational, i.e. the LCLS in the USA and SACLA in Japan. In particular, the structure of two photoswitching intermediates have been determined, one featuring a twisted chromophore in the excited state and the other displaying a protonated cis isomer of the chromophore in the ground state. The structural characterization of rsEGFP2 variants by traditional oscillation crystallography combined with the serendipitous discovery of an alternate chromophore conformation in the off-state during an XFEL experiment provided unique insight into the photophysical behavior of the protein
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Jradi, Fadi M. "Organic light-harvesting materials for power generation." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54976.
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This dissertation focuses on the design, synthesis, and characterization of a variety of organic dyes, semiconducting materials, and surface redox-active modifiers of potential interest to organic-based emerging photovoltaics. A discussion of the materials’ optoelectronic properties, their ability to modify and promote electron transfer through an organic/transparent conducting-oxide interface, and finally their effect on the photovoltaic properties of devices utilizing them as light-harvesters is provided where relevant. The first two research chapters discuss mono-chromophoric asymmetric squaraine-based sensitizers and covalently linked, dual-chromophoric, porphyrin-squaraine sensitizers as light absorbers in dye-sensitized solar cells (DSSCs), in an attempt to address two problems often encountered with DSSCs utilizing this class of near infra-red sensitizers; The lack of panchromatic absorption and aggregation on the surface. Also, this dissertation discusses the design and synthesis of asymmetric perylene diimide phosphonic acid (PDI-PA) redox-active surface modifiers, and reports on the electron-transfer rates and efficiencies across the interface of an ITO electrode (widely used in organic-electronic devices) modified with these perylene diimides. Finally two series of hole-transport materials based on oligothiophenes and benzodithiophenes are reported: optoelectronic properties and preliminary performance of organic photovoltaic (OPV) devices fabricated with them is discussed.
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Ma, Pei. "OPTICAL IMAGING OF EMBRYONIC CARDIAC CONDUCTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1464714110.
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Young, Eleanor Dawn, and ellie@goldstreetstudios com au. "Mechanisms of Controlling Colour and Aesthetic Appearance of the Photographic Salt Print." RMIT University. Applied Science, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080901.142948.
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Abstract The salt print is an important part of photography, both in its historic value and in the tonal range it can provide. This tonal range is greater than any other photographic printing process available to date attributed to the inherent masking ability of the metallic silver. However the intrinsic production problems have made it a 'forgotten' process. There are five key problems. 1. The difficulties in achieving the potential extensive tonal range. 2. The varying colour of the print. 3. Staining that appears in the print, during and after processing. 4. Instability and longevity of the salt print. 5. Contradictory and inaccurate information in material published on the salt print. Although the emphasis of the research is on exploring and controlling the colour and tonal range, the staining problems and stability of the print are also addressed. The materials used for contact negatives today vary in both capture and output, from analogue film processed in the traditional wet darkroom to a variety of transparent film printed from digital files. Inadequate density and tonal range can affect all types of negatives. To provide sufficient exposure time for the salt prints extended tonal range adjustments to the negative were necessary. These long exposures then converted sufficient silver salts to the image making metallic silver, utilising the intrinsic self-masking process. Ultimately this research has uncovered ways to control colour and tonal range and certain aesthetic qualities of the salt print, while simultaneously resolving some of the conflicts in published information. Accurate and consistent methods of processing eliminate staining, providing some stability to the print. The activities and steps carried out to make a salt print are manual; precise duplication is therefore almost unattainable. Nevertheless, although tests on a densitometer may display numeric differences, visual differences are barely noticeable.
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Werts, Martinus Henricus Valentinus. "Luminescent lanthanide complexes visible light sensitised red and near-infrared luminescence /." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/83075.
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Pettersson, Rimgard Belinda. "Light Intensity Dependence of Charge Recombination in Dye-Sensitized NiO films." Thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227635.
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Knott, Andrew N. "3D printing of light trapping structures for dye-sensitised solar cells." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/50058/.
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Converting solar energy directly into electricity as a clean and renewable energy resource is immensely important to solve the energy crisis and environmental pollution problems induced by the consumption of fossil fuels. Dye-sensitised solar cells have attracted a great deal of attention following their development in 1991. They provide a technically and economically credible alternative that could challenge the dominance of conventional p-n junction photovoltaic devices in the solar energy market. 3D printing and other additive manufacturing techniques allow the fabrication of geometrically complex end-use products and components in a variety of materials by using technologies that deposit material layer-by-layer. The additive manufacturing of optoelectronic devices is still in its infancy but has the potential to completely revolutionise the industry. Two-photon polymerisation is a technique used to fabricate 3D structures with resolutions down to a few hundred nanometres. The technique shows the ability to fabricate highly complex 3D structures of arbitrary shape with unprecedented levels of control. In this thesis the two-photon polymerisation 3D printing technique is used to fabricate TiO2 thin films of optimised 3D micro-design for use in DSSCs. Our 3D printed films have a considerable advantage over the conventional (random assembly) films, as they allow the implementation of optimised light trapping designs directly into the cell. Cells are characterised with scanning photocurrent microscopy with results showing these light trapping structures are able to improve photocurrent generation by up to approximately sim 9%$ when compared to conventional random assembly TiO2.
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Lakadamyalı, Fezile. "Solar light driven hydrogen evolution with cobaloximes modified on dye-sensitised TiO₂." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708088.
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Vladimir, Shuster. "Phenazine: A Building Block for Multinuclear and Heterometallic Complexes, Where the Ligand Acts as an Electron Acceptor and Radical Abstractor." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24234.
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Over the past decade, intensive academic and commercial interests have been paid on compounds possessing photochemical properties, namely for their preparation, chemical properties, high efficiency and potential low-cost.
Compounds having intense photochemical properties gained great interest due to wide range of potential applications. The sensitizers are one of the key components for high power-conversion efficiency in the dye sensitized solar cells (DSSCs). They are the core components in the organic light-emitting devices (OLEDs) due to their ability to emit light with the wavelengths largely red- shifted from their absorption wavelength. Ruthenium based sensitizers have been tagged “molecular light switches” because, although the fluorescence of these complexes in aqueous solutions is negligible, it increases of greater than 10000 fold in the presence of DNA. Many polypyridyl and dipyrido phenazine ruthenium complexes have achieved high power conversion efficiencies and therefore are of practical interest. Several research groups stated that the dipyrido phenazine ligand may be thought of as comprising two components: a bipyridyl unit and a phenazine unit. These two subunits behave essentially separately, with many molecular orbitals being localised over only one subunit and a redox properties of central phenazine moiety in the dipyrido phenazine ligand are important for the photochemical applications.
Therefore a phenazine ligand was selected as a model for the present investigation. The chemistry of phenazine ligand is mostly limited to the late transition metal and f - element complexes. Our laboratory has a rich backgroung in the aluminum and early transition metal chemistry. The aluminum chemistry and early transition metal chemistry are of great interest since aluminum and early transition metal complexes are environmentally friendlier and cheaper than the late transition metal compounds. Another drawback of the ruthenium-based sensitizers is the lack of absorption in the red region of the visible spectrum, and also low molar extinction coefficients. An essential requirement for efficient conversion of solar energy is the good spectral match of the sensitizer absorption to the emission spectrum of solar radiation. In this regard, the ruthenium sensitizers’ spectral response in the lower energy regions is not sufficient.
The current project has three parts. In the first part we collected and reviewed known literature regarding the certain classes of non-innocent ligands containing the six-membered carbon- nitrogen heterocycles and regarding the ligands potentially important for the photochemical applications. We also reviewed all available to the data information about the complexes supported by the phenazine ligand.
In the second part we have investigated interaction of alkylaluminum compounds and phenazine and observed reduction of phenazine accompanied by formation of dialuminum cage type compounds containing two formally mononegative phenazine ligand. The derivatization of phenazine has been also observed. It resulted in formation of compounds having a stable organic radical.
In a third part of our project we have explored interaction of phenazine or thiophenazine with the alkylaluminum compounds and chromium dichloride. The reaction in the three component system resulted in reduction of phenazine ligand and lead to the heterometallic Cr(II) - aluminum complexes containing a formally dinegative phenazine or thiophenazine ligands. When a large excess of triethylaluminum was taken, reduction of phenazine and chromium has been observed leading to the heterometallic multinuclear Cr(I) - aluminum complex containing a formally dinegative phenazine ligands and two chromium atoms in one complex in the rare oxidation state one.
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Davis-Wheeler, Chin Clare. "Platinum@Hexaniobate Nanopeapods: Sensitized Composite Architectures for Photocatalytic Hydrogen Evolution Under Visible Light Irradiation." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2503.
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Hydrogen fuel is one of the most important areas of research in the field of renewable energy development and production. Hydrogen gas can be generated by fuel cells, water electrolyzers, and heterogeneous nanoscale catalysts. It can be burned to directly release chemical energy or condensed for storage and transport, providing fuel for combustion devices or storing excess energy generated by renewable sources such as wind turbines and concentrated solar power assemblies. While platinum is the most active catalyst for hydrogen reduction, its high cost significantly deters its utilization in advanced photocatalytic materials. One approach to mitigating this expense is optimizing the morphology and placement of nanostructured platinum catalysts. Highly crystalline, morphologically-controlled platinum nanoparticles (Pt NPs) have been effectively utilized to increase hydrogen generation efficiency in a variety of nanocomposite materials. However, synthesis routes to high-quality Pt NPs can be dangerous and difficult to replicate. Furthermore, utilization of the Pt NPs in nanocomposite materials is hindered by lack of control over catalyst placement.
Nanopeapods are versatile nanocomposites that offer a high degree of control over catalyst placement as well as the potential for interesting new properties arising from the interaction between the catalyst and a semiconductor. Platinum@hexaniobate nanopeapods (Pt@HNB NPPs) consist of linear arrays of Pt NPs encapsulated within the scrolled semiconductor hexaniobate. Pt@HNB NPPs offer significant advantages over similar composites by utilizing the isolated reduction environment of the encapsulated Pt NP arrays to decrease kinetic competition and surface crowding.
This work describes the design, fabrication, and implementation of the new nanocomposite platinum@hexaniobate nanopeapods for sensitized hydrogen production under visible light irradiation. The following chapters present facile microwave heating syntheses of highly crystalline Pt nanocubes and Pt@HNB NPPs with consistent morphology and high catalyst loading. A detailed study is also presented of the optical properties of the Pt nanocubes, which produced a UV-range absorbance band that indicates the formation of a localized surface plasmon resonance. Most significantly, preliminary results from visible light photolysis indicate that sensitized Pt@HNB NPPs produce hydrogen in quantities comparable to published systems, and that alteration of experimental parameters may result in even greater yields.
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Wang, Qiwei. "New functional molecules and polymers for organic light-emitting diodes and solar cells." HKBU Institutional Repository, 2010. http://repository.hkbu.edu.hk/etd_ra/1200.
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Lissau, Jonas Sandby. "Non-Coherent Photon Upconversion on Dye-Sensitized Nanostructured ZrO2 Films for Efficient Solar Light Harvesting." Doctoral thesis, Uppsala universitet, Fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229831.
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Photon upconversion by sensitized triplet–triplet annihilation (UC-STTA) is a photophysical process that facilitates the conversion of two low-energy photons into a single high-energy photon. A low-energy photon is absorbed by a sensitizer molecule that produces a triplet excited state which is transferred to an emitter molecule. When two emitter triplet states encounter each other, TTA can take place to produce a singlet excited state which decays by emission of a high-energy (upconverted) photon. While traditional single-threshold dye-sensitized solar cells (DSSCs) have a maximum efficiency limit of ca. 30%, it has been predicted theoretically that implementation of UC-STTA in DSSCs could increase that efficiency to more than 40%. A possible way to implement UC-STTA into DSSCs, would be to replace the standard sensi- tized nanostructured TiO2 photoanodes by upconverting ones loaded with emitter molecules. Following TTA, the excited emitter molecule would be quenched by injection of a high-energy electron into the conduction band of the TiO2. To explore the practical aspects of this strategy for a highly efficient DSSC, in this thesis UC-STTA is studied in model systems based on nanostructured ZrO2 films. These ZrO2 films are a good proxy for the TiO2 films used in DSSCs, and allow for relatively easy optimization and study of UC-STTA by allowing measurements of the upconverted photons without the complications of electron injection into the film. Herein it is experimentally proven that UC-STTA is viable on nanostructured metal oxide films under non-coherent irradiation with intensities comparable to sunlight. Two different system architectures are studied, differing in the position of the molecular components involved in the UC-STTA mechanism. Both architectures have the emitter molecules adsorbed onto the ZrO2 surface, but the sensitizers are positioned either in solution around the nanostructure, or co-adsorbed with the emitters onto the ZrO2 surface. A set of challenges in the study and optimization of the UC-STTA process is identified for each type of system. Proposals are also given for how to further improve the understanding and UC-STTA optimization of these systems toward application in DSSCs to overcome the present solar energy conversion efficiency limit.
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Brown, M. D. "Light harvesting and photoconversion efficiency enhancement in dye-sensitized solar cells via molecular and photonic advancements." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:651f8967-5d8b-42aa-bee1-04e0bbc04cea.
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The main goal of this thesis is to investigate and develop the physics of dye-based photovoltaic physics through molecular and photonic routes. Numerous photovoltaics devices have been fabricated through the course of this work to study their characteristics, performance, physical composition and action. The relative youth of the field of dye-based optoelectronics provides extensive scope for new research which provides fascinating opportunities in terms of physical processes.This thesis is divided into two main projects; exploring the adaption of conventional dye-sensitized solar cells via starkly different routes which serendipitously culminated in striking similarities at their conclusion. The first route is through incorporating spectrally complementary dye molecules with the intention of extending the range of light absorption of the final devices. This initial aim was achieved and was then furthered by the realisation of an unexpected and unprecedented energy transfer process occurring, imparting enhanced photocurrent generation in both the near-IR and visibile region. The second route involves investigating the effect on dye-sensitized solar cell physics and performance of the inclusion of metallic nanoparticles with the expectation of inducing plasmonic interactions. Novel systems were designed and implemented, devices were made which display significant performance enhancement, attributed to plasmonic coupling into the dyes and thereby increasing photocapture. A number of other investigations are documented whose current completion does not sufficiently warrant independent chapters but whose scientific interest is evident.
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Mahrov, Boriss. "Studies of Semiconductors Modified with Nanoscale Light Absorbers for Solar Cell Application." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4581.
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Yang, Yiqun. "Integration of photosynthetic pigment-protein complexes in dye sensitized solar cells towards plasmonic-enhanced biophotovoltaics." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32857.
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Doctor of PhilosophyDepartment of Chemistry
Jun Li
Solar energy as a sustainable resource is a promising alternative to fossil fuels to solve the tremendous global energy crisis. Development of three generation of solar cells has promoted the best sunlight to electricity conversion efficiency above 40%. However, the most efficient solar cells rely on expensive nonsustainable raw materials in device fabrication. There is a trend to develop cost-effective biophotovoltaics that combines natural photosynthetic systems into artificial energy conversion devices such as dye sensitized solar cells (DSSCs). In this research, a model system employs natural extract light-harvesting complex II (LHCII) as a light-absorbing sensitizer to interface with semiconductive TiO₂ and plasmonic nanoparticles in DSSCs. The goal of this research is to understand the fundamental photon capture, energy transfer and charge separation processes of photosynthetic pigment-protein complexes along with improving biophotovoltaic performance based on this model system through tailoring engineering of TiO₂ nanostructures, attaching of the complexes, and incorporating plasmonic enhancement. The first study reports a novel approach to linking the spectroscopic properties of nanostructured LHCII with the photovoltaic performance of LHCII-sensitized solar cells (LSSCs). The aggregation allowed reorganization between individual trimers which dramatically increased the photocurrent, correlating well with the formation of charge-transfer (CT) states observed by absorption and fluorescence spectroscopy. The assembled solar cells demonstrated remarkable stability in both aqueous buffer and acetonitrile electrolytes over 30 days after LHCII being electrostatically immobilized on amine-functionalized TiO₂ surface. The motivation of the second study is to get insights into the plasmonic effects on the nature of energy/charge transfer processes at the interface of photosynthetic protein complexes and artificial photovoltaic materials. Three types of core-shell (metal@TiO₂) plasmonic nanoparticles (PNPs) were conjugated with LHCII trimers to form hybrid systems and incorporated into a DSSC platform built on a unique open three-dimensional (3D) photoanode consisting of TiO₂ nanotrees. Enhanced photon harvesting capability, more efficient energy transfer and charge separation at the LHCII/TiO₂ interface were confirmed in the LHCII-PNP hybrids, as revealed by spectroscopic and photovoltaic measurements, demonstrating that interfacing photosynthesis systems with specific artificial materials is a promising approach for high-performance biosolar cells. Furthermore, the final study reveals the mechanism of hot electron injection by employing a mesoporous core-shell (Au@TiO₂) network as a bridge material on a micro-gap electrode to conduct electricity under illumination and comparing the photoconductance to the photovolatic properties of the same material as photoanodes in DSSCs. Based on the correlation of the enhancements in photoconductance and photovoltaics, the contribution of hot electrons was deconvoluted from the plasmonic near-field effects.
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Pöttinger, Leo [Verfasser], and Thomas [Akademischer Betreuer] Bürgi. "Spectroscopic characterization of dye sensitized TiO₂ with CO₂ co-adsorption and visible light excitation / Leo Pöttinger ; Betreuer: Thomas Bürgi." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1177810808/34.
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Chen, Shao-Chiao, and 陳少喬. "Parametric Light-Sensitive Facade Design." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/57171591869893145670.
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碩士淡江大學
建築學系碩士班
100
This research discusses on the meanings of various transformations and forms of facade, based on the investigation on different possibilities of wall design, which shows the feeling of interior space affected by sunlight. To show the diverse functions of different walls, Rhinoceros and its well-integrated parametric tool Grasshopper, are two major tools in subsequent operations, generating different configurations by adjusting parameters. Moreover, through the discussions between various factors and sunlight, a new design methodology developed through computational tools. The main topic is to suggest a setting on parameters by diverse functions which results from wall modification, will contribute to the most suitable adjustment between the space and the usages of building skin. It works on premise that wall will change under different circumstances, such as interior factors, quantities of users, characteristic of usage, even the exterior factors also. As an interface between interior and exterior, a unidirectional relationship which is prompted by sunlight, wall and users, the discussion also creates different correlations among these factors. People’s behaviors and environmental factors will finally affect on the wall, the change of different factors should redefine the relationship between sunlight and space, and it can happen in various ways. This research consists of three parts: 1.Tectonic and Kinetic Structure: Parametric tool is applied to design regular textures of the wall, and the discussion on the tectonic affects by the sunlight, besides simulate the interior lighting effect by just a simple cube. 2.Configuration of Wall’s Parameters: Diverse parameters are used to modify the forms of wall, to investigate the diversities which presented by interior space under different sunlight with various parameters. 3.Connection between Interior and Exterior: Wall is a medium, and how the changes of wall will influence the relationships between interior and exterior. The wall reacts on diverse change which occurred by both interior and exterior factors, moreover users’ behaviors and requirements could be reflected by the forms of facade itself. The whole process emphasizes on the connection in-between interior and exterior of the space. This research establishes a new challenge on building skins design, as well as to expand the possibilities of design thinking in facade design. In having a goal to breaking through recent knowledge of facade, a new articulation is created between human being and nature by redesigning a wall. We anticipate that it could be a reference of facade design to who involved in study of sustainable development of architecture in future.
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Chen, Shiou-Ying, and 陳琇瑛. "High-sensitive light spot position sensing detector." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/b92e38.
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碩士國立虎尾科技大學
光電與材料科技研究所
96
This paper proposed a light spot position sensing detector which has high sensitivity and is capable of separating the background light. We uses a photo- transistor matrix (19 × 19 pixels), a trans-impedance amplifier, and a lock-in amplifier to form this position sensitive detector. This detector extracts the modulation light spot form the background light and utilizes a analog computation circuit to obtain the light spot position. The circuit use TSMC 0.35 μm process model for simulation and results show that the smallest detectable photo current is 1nA, the consumed power is lower than 150mW, and the overall linear is as high as 70%.
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Fromme, Ulrich. "Investigation of voltage- and light-sensitive ion channels." Doctoral thesis, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-87F1-5.
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Hubbard, Frank Pierce. "Investigation of aggregate microstructures formed by light-sensitive surfectants." 2006. http://www.library.wisc.edu/databases/connect/dissertations.html.
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LIn, Wen-Chung, and 林文中. "Light-sensitive properties of 2-(2-nitrophenyl)-tetrahydroquinolines and their applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/64394949414035449912.
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博士東海大學
化學系
102
Our laboratory has recently reported a novel o-nitrophenyl-substituted oxazabicycle-based photochromic colorant. Upon exposure to UV light in CH2Cl2, it turned purple and reverted back to its original color while being heated. In this thesis, we investigated light-sensitive properties of this molecular scaffold and its photochromic mechanism. First, in situ trapping of the photogenerated product with trimethylsilyl cyanide confirmed the formation of the ring-opened zwitterionic species. Second, the EPR spectroscopic data, PBN spin-trapping experiments, and spectroelectrochemical studies of the model compound strongly supported that the photochromism involved the formation of a zwitterionic biradical intermediate, generated by photoinduced intramolecular electron transfer from the amine moiety to the nearby o-nitrophenyl group. Finally, two photogenerated side products responsible for photofatigue of the oxazabicycle were isolated and characterized, and a possible mechanism for their formation was proposed. On the basis of light-sensitive properties of o-nitrophenyl-substituted quinoline, we have further developed a green and sustainable synthetic methodology for the preparation of pharmaceutically important indazole derivatives. First, the 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinoline precursors were obtained via Povarov reaction by p-TsOH-catalyzed coupling of the commercially available aromatic amines, 2-nitro aromatic aldehydes, and alkenes. Second, the indazolo[2,3-a]quinoline derivatives were synthesized in moderate to good yields via visible light photoredox catalysis (VLPC). The key step of this visible light promoted reaction involved a novel ruthenium-catalyzed intramolecular formation of the N－N bond of the indazole ring. Finally, the substrate scope, the potential of one-pot preparation along with the proposed mechanism of this VLPC-mediated reaction were explored.
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"Crossroads --- A Time-Sensitive Autonomous Intersection Management Technique." Master's thesis, 2017. http://hdl.handle.net/2286/R.I.43965.
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abstract: For autonomous vehicles, intelligent autonomous intersection management will be required for safe and efficient operation. In order to achieve safe operation despite uncertainties in vehicle trajectory, intersection management techniques must consider a safety buffer around the vehicles. For truly safe operation, an extra buffer space should be added to account for the network and computational delay caused by communication with the Intersection Manager (IM). However, modeling the worst-case computation and network delay as additional buffer around the vehicle degrades the throughput of the intersection. To avoid this problem, AIM, a popular state-of-the-art IM, adopts a query-based approach in which the vehicle requests to enter at a certain arrival time dictated by its current velocity and distance to the intersection, and the IM replies yes/no. Although this solution does not degrade the position uncertainty, it ultimately results in poor intersection throughput. We present Crossroads, a time-sensitive programming method to program the interface of a vehicle and the IM. Without requiring additional buffer to account for the effect of network and computational delay, Crossroads enables efficient intersection management. Test results on a 1/10 scale model of intersection using TRAXXAS RC cars demonstrates that our Crossroads approach obviates the need for large buffers to accommodate for the network and computation delay, and can reduce the average wait time for the vehicles at a single-lane intersection by 24%. To compare Crossroads with previous approaches, we perform extensive Matlab simulations, and find that Crossroads achieves on average 1.62X higher throughput than a simple VT-IM with extra safety buffer, and 1.36X better than AIM.Dissertation/Thesis
Masters Thesis Engineering 2017
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Abbott, Scott John. "Photo-induced reversible changes in wettability on light sensitive pyrimidine-coated surfaces." 2000. http://arrow.unisa.edu.au:8081/1959.8/78700.
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Thin coatings of photoresponsive, pyrimidine-terminated molecules, attached to gold or quartz substrates in contact with water, undego photodimerisation and wettability changes when irradiated with UV light at 280 and 240mm. Spin-casting and chemisorption techniques were used to prepare the thin films.Thesis (PhDApSc)--University of South Australia, 2000.
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Huang, Bo-Rong, and 黃柏融. "The Application of Light-Sensitive Ink in Metalization on a Flexible Substrate." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/68674842939417693086.
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碩士國防大學理工學院
化學工程碩士班
104
In this study, a photoreactive and metal-platable polymer ink is developed and used for electroless copper plating. The substrate is first immersed in a mixture consisting of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819) as photoinitiator, urethane acrylate oligomer as crosslinking agent, diethylene glycol diacrylate as the monomer, polyvinylpyrrolidone (PVP K30) as the adhesive, and N, N 'methylene bisacrylamide (MBAA) to form a uniform layer on the PET substrate. Then, the photoreactive layer is irradiated with an UV light of wavelength of 365 nm to initiate the polymerization reaction to form a cross-linking polymer layer, which is subsequently used to immobilize catalytic species for electroless deposition of metal. Subsequent to UV exposure through a mask, the catalytic species, palladium ions, can be spin-coated onto the polymer modified substrate, where PdCl4-2 ions are immobilized onto the selective area. An alternative strategy, namely inkjet printing, is also used to prepare the selective pattern. After electroless plating, the specific Cu pattern is obtained. The resulting Cu layer with a thickness of 2.12 μm exhibits good electrical and adhesion performance. The copper pattern shows a sheet resistance of 0.51 Ω / Sq even after 500 cycles bending test.