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1
Rowe, Christopher Brian. "The influence of habitat features and co-occurring species on puma (Puma concolor) occupancy across eight sites in Belize, Central America." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82032.
Full textAbstract:
Large carnivores play many vital biological, economic, and conservation roles, however, their biological traits (low population densities, cryptic behavior) make them difficult to monitor. Pumas have been particularly difficult to study because the lack of distinctive markings on their coats prevents individual identification, precluding mark-recapture and other similar analyses. Further, compared to temperate areas, research on the interspecific interactions of Central American felids is particularly lacking. I used single- and multi-season, single-species occupancy models and two-species co-occurrence models to analyze camera trapping and habitat data collected at eight study sites across Belize. Puma occupancy was positively influenced by jaguar trap success, understory density, canopy cover, and human trap success, and negatively influenced by stream density. Jaguar trap success was the best predictor of where pumas occurred, while prey species were not found to influence puma occupancy. Mean occupancy was 0.740 (0.013) and ranged from 0.587 (0.042) to 0.924 (0.030). Over time, puma occupancy rates were generally high (> 0.90) and stable. Puma occupancy was higher in logged areas, suggesting that current levels of natural resource extraction at those sites were not detrimental to the species. Co-occurrence modeling showed little evidence for interactions between the carnivores, suggesting that jaguars may be acting as an umbrella species and that conservation efforts directed at jaguars are likely to benefit the other carnivores, including pumas. Overall, these findings are positive for puma conservation, but human-induced land use change is expanding and further monitoring will give us insight into how pumas respond to human encroachment.Master of Science
2
Stromgren, Eric Johnston. "Improving livetrapping methods for shrews (Sorex spp.)." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2743.
Full textAbstract:
Known for their high metabolism, shrews possess an incessant need to eat high
quality foods. This drives much of the biology of shrews and has caused great difficulties
when attempting to study shrews using mark-recapture methods. I reviewed the literature
and identified potential causes of varied trappability in small mammals. Weather related
factors were important in determining activity levels and thus trappability. Social
relationships (both inter- and intraspecific) were found to contribute to trappability, in
some cases with dominant individuals completely excluding subordinates from traps.
Trap type was the easiest factor for a researcher to vary, and thus received most of the
attention in the published literature. Sherman, pitfall, and Longworth traps were
commonly used, and although pitfall traps are commonly used as removal traps, there is
the potential for their use as live traps. The pitfall and Longworth traps seemed the most
appropriate for capture of particularly small mammals, especially shrews; however
comparisons between these three trap types were confounded by differing methods used
for each trap type, and small sample sizes. I tested the relative efficiencies of pitfall and
Longworth traps for livetrapping vagrant shrews (Sorex vagrans), and found the
Longworth trap to be much more efficient, capturing up to five times as many individual
shrews as pitfall traps. I also tested the utility of addition of mealworms as food for
shrews, and the effect of increased trap check frequency on the trap mortality rates of
vagrant shrews. The addition of mealworms significantly reduced mortality rates, and the
addition of one midday trap check, so that traps were not left open for more than 8 h,
reduced overall trap mortality rates in mealworm baited traps from nearly 60% (in non
mealworm baited traps, checked at 12 h intervals) to less than 10%. Finally, I tested the
effect of drift-fences on capture rates of shrews in pitfall and Longworth live traps on
riparian and upland traplines. I found no significant differences between the trap types, or
between traps equipped with drift-fences, and those without. However, any effect would
have been masked by overall low trap success during this experiment.
3
Antal, Peter. "Trapping problems for the simple random walk /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10759.
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4
Dare, Kahan McAffer. "Tools for trapping and detecting ultracold gases." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57889.
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We construct a vertical imaging system designed to image along the quantization axis of the experiment. We demonstrate that it has a resolution on the order of 1-2μm which is on par with previous characterizations of the constituent components. We find that the inclusion of the vertical imaging system has a detrimental effect on the atom loading performance of the MOT. We show that this decrease is by approximately a factor of 2 down to 6.5×10⁶ atoms per second and 8.1×10⁷ atoms respectively. We subsequently detail the design of a novel lattice apparatus capable of tuning the lattice spacing by many orders of magnitude on the timescale of a typical experimental cycle. A proof-of-principle for this so-called dilating lattice is realized and the mechanism for variable lattice spacing is shown to work. Lastly, we cover our efforts towards measuring the effect of Feshbach resonances on collisional decoherence rates in ⁶Li. To this end, we show that the Rabi frequency we can create given our current tools is approximately 100Hz. A unknown strong mechanism for decoherence obstructs our experimental signature and a brief discussion of our attempts to discover its origin is presented.Science, Faculty of
Physics and Astronomy, Department of
Graduate
5
Wu, J. "Materials for electron trapping optical memory (ETOMS)." Thesis, Coventry University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289102.
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Saxton, Carl Graham. "Microporous adsorbents for trapping of gaseous pollutants." Thesis, University of Aberdeen, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446326.
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Adsorption studies (xenon and iodine) in microporous materials have been carried out on various materials such as zeolites (FAU, MFI, SAV and CHA) and metal-organic frameworks (MOF-5, HKUST-1 and JUC-32). The as-synthesised and commercial zeolites containing Na+, Li+ or K+ cations and then subsequently ion-exchanged for other extra framework cations. The xenon adsorption in zeolites was interpreted using isosteric heats of adsorption (CHA) and also 129Xe NMR (FAU). CHA type zeolites show a high affinity and capacity for xenon at low xenon pressures <10kPa. This affinity changes depending upon the extra framework cation present due to the positioning and size of the cation. The electric field gradient was a primary factor in the xenon adsorption since a neutral framework (ALPO-CHA) was found to have a lower affinity for xenon but having the same framework type. This was further highlighted by the introduction of Si into the framework and a comparison was made between the three structures CHA, ALPO-CHA and SAPO-34 with the latter being a silicon substituted aluminophosphate carrying a slightly negatively charged framework. Another framework studied was that of STA-7 (SAV) and it was found that varying the silicon within the framework had an effect upon the xenon adsorption. Xenon interaction with the MOFs was minimal when compared to the zeolites. MOF materials adsorbed more iodine per gram of material than any of the zeolites studied. In some materials, two different species of iodine exist. These species, I2 (isolated) and (I2)n (wires) have different Raman frequencies and the (I2)n species have been observed in MOFs for the first time.
7
Head, Christopher Robin. "Optical trapping and optical sources for nanophotonics." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/359888/.
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In this thesis I describe work that I have done in two separate research areas. The first involves optical micro manipulation of nano-scale objects and their orientation. The second concerns the development of a semiconductor laser to provide high beam quality,average and peak power and short pulse durations. Optical tweezers are an excellent tool to manipulate nano scale objects in all three dimensions. An additional degree of control, the rotational alignment of assymetrical particles, is demonstrated by polarisation analysis of two photon induced fluorescence of the trapped and rotated semiconductor nanorods.Mode-locked vertical external-cavity surface emitting lasers (VECSELs) have recently achieved multi-watt average power levels. Nevertheless the need to optimize the gain structure design, in order to consistently obtain sub 200 fs pulse durations, still remains. The evolution of the intra-cavity power build-up transient is utilized for a novel spectro-temporal technique which allows for the extraction of the curvature of the gain spectrum during actual operation and enables the observation of the evolution of the gain spectrum during lasing build-up. In addition a method to obtain the total cavity loss via the combination of the power build-up transient and photo luminescence decline, during lasing onset is shown. The use of an amplified, femtosecond-pulsed and GHz repetition rate VECSEL to generate multi-watt average power supercontinuum in photonic crystal fibres (PCFs) is presented. Supercontinuum generation with GHz pulse repetition rates is of interest for frequency combs as the high repetition rate increases the mode spacing of the comb and energy per mode. Two different PCFs, one with an all-normal dispersion profile and one with a zero dispersion wavelength (ZDW) at 1040 nm, are pumped with the amplified VECSEL pulses generating spectral components over 200 nm and 500 nm, respectively. The thesis concludes with a proposal to use the advantages of both optical tweezers and VECSELs to analyse and resonantly excite the vibrational frequencies of single nano-scale objects.
8
Barron, Ashleigh Louise. "Integrated multicore fibre devices for optical trapping." Thesis, Heriot-Watt University, 2014. http://hdl.handle.net/10399/2805.
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The work described in this thesis details the development of a multicore fibre device that can be used to optically trap multiple cells and particles. The optical trapping of multiple cells at close proximity allows for cell-to-cell interactions to be studied. Current methods available for creating arrays of traps are free space optical systems that use diffractive optics, laser scanning techniques or the interference of multiple beams to create the multiple traps. A fully integrated, fibre optic based, multiple particles, optical trapping device could be used in non-optical research facilities such as biological laboratories to aid with their research into cellular processes. In order to create the multiple traps, the distal end of the multicore fibre needs to be modified to induce a lensing effect. The multicore fibre device presented in this thesis was lensed in a fusion splicer; this refracts the outputs from the four cores to a common point in the far field where interference fringes are formed. The initial investigation demonstrated one-dimensional interferometric optical trapping through coupling light into two of the diagonal cores of the lensed multicore fibre. This produced linear interference fringes approximately 250 ± 25 μm from the end of the fibre with a fringe spacing of 2 ± 0.3 μm. The linear interference fringes were used to optically trap polystyrene microspheres with diameters of 1.3 μm, 2 μm and 3 μm in the high intensity regions of the fringes. Coupling into all four cores using a diffractive optical element produced an array of intensity peaks across the interference pattern with high visibility fringes greater than 80 %. Each intensity peak, spaced 2.75 μm apart could trap a single particle in two dimensions. The optical trapping of multiple microspheres and Escherichia coli bacterial cells was demonstrated proving that the lensed multicore fibre has the potential to be used to trap cells in biological experiments. The active manipulation of trapped 2 μm microspheres was also demonstrated through the rotation of the input polarisation to the multicore fibre. Finally, work towards creating a “turn-key” optical trapping device was demonstrated through the fabrication of a fully integrated multicore fibre device using an ultrafast laser-inscribed fan-out to couple light into each core. Single mode operation of the device was demonstrated at 1550 nm, using a weaker lensed MCF device. The two dimensional trapping of 4.5 μm polystyrene microspheres was shown in an array of peaks spaced 11.2 μm apart at a distance of 400 ± 25 μm from the end of the fibre.
9
De, Motte Darren C. E. "Cryogenic ion trapping for next generation quantum technologies." Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/66011/.
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Quantum technology has made great strides in the last two decades with trapped ions demonstrating all the necessary building blocks for a quantum computer. While these proof of principle experiments have been demonstrated, it still remains a challenging task to scale these experiments down to smaller systems. In this thesis I describe the development of technology towards scalable cryogenic ion trapping and quantum hybrid systems. I first discuss the fundamentals of ion trapping along with the demonstration of ion trapping on a novel surface electrode ion trap with a ring shaped architecture. I then present the development of a cryogenic vacuum system for ion trapping at ~4 K, which utilizes a closed cycle Gifford McMahon cryocooler with a helium gas buffered ultra-low vibration interface to mechanically decouple a ultra-high vacuum system. Ancillary technologies are also presented, including a novel in-vacuum superconducting rf resonator, low power dissipation ceramic based atomic source oven and an adaptable in-vacuum permanent magnet system for long-wavelength based quantum logic. The design and fabrication of microfabricated surface ion traps toward quantum hybrid technologies are then presented. A superconducting ion trap with an integrated high quality factor microwave cavity and vertical ion shuttling capabilities is described. The experimental demonstration of the cavity is also presented with quality factors of Q6~6000 and Q~15000 for superconducting niobium nitride and gold based cavities respectively, which are the highest demonstrated for microwave cavities integrated within ion trapping electrode architectures. An ion trap with a multipole electrode geometry is then presented, which is capable of trapping a large number of ions simultaneously. The homogeneity of five individual linear trapping regions are optimized and the design for the principle axis rotation of each linear region is presented. An overview of microfabrication techniques used for fabricating surface electrode ion traps is then presented. This includes the detailed microfabrication procedure for ion traps designed within this thesis. A scheme for the integration of ion trapping and superconducting qubit systems as a step towards the realization of a quantum hybrid system is then presented. This scheme addresses two key diffculties in realizing such a system; a combined microfabricated ion trap and superconducting qubit architecture, and the experimental infrastructure to facilitate both technologies. Solutions that can be immediately implemented using current technology are presented. Finally, as a step towards scalability and hybrid quantum systems, the interaction between a single ion and a microwaves field produced from an on chip microwave cavity is explored. The interaction is described for the high-Q microwave cavity designed in this thesis and a 171Yb+ion. A description of the observable transmission from the cavity is described and it is shown that the presence of a single ion can indeed be observed in the emission spectrum of high-Q microwave cavity even in the weak coupling regime.
10
Boyd, Micah (Micah Scott). "Novel trapping techniques for shaping Bose-Einstein condensates." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/39296.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, February 2007.Includes bibliographical references (p. 125-133).
A combination of radio frequency radiation and magnetic field gradients was used to trap atoms in dressed states. In a magnetic field with a quadrupole minimum. RF fields resonant with the (I F. m)) 11. -1) -- 1, 0) transition trapped the atoms on the surface of a sphere, and gravity caused the atoms to pool at the bottom of the sphere. BECs were transferred into this dressed Zeeman trap with 100% efficiency, with lifetimes of up to 30 s, and trapping frequencies of up to 250 Hz were measured. A hard disk platter with a specially written magnetic pattern was used to generate magnetic fields to confine atoms tightly. Detrimental interactions with the surface were avoided by using an extremely thin film with a large magnetic remnant. BECs of up to 5 x 10" atoms were produced in cigar shaped traps -40 pin above the surface, and trap frequencies up to 5 kHz were measured. After evaporation, condensed clouds moved(] closer to the surface to probe imperfections in the magnetic potential, revealing defects at distances closer than 35 prn. Finally, BECs were dropped from a height of 350 pm in an attempt to achieve specular reflection. but a large amount of dispersion was observed.
(cont.) Finally, BECs were loaded into a three-dimensional optical lattice, and a quantum phase transition from a superfluid to a Mott insulator was observed. Using microwave spectroscopy. the density dependent "clock shift" was was found to depend on the occupation number of the wells. The singly occupied lattice sites were then investigated as an atomic clock system with no density shift. Linewidths as small as 1 Hz FWHMI out of 6.8 GHz are comparable to current atomic frequency standards.
by Micah Boyd.
Ph.D.
11
Nakidde, Diana. "Insulator-based Dielectrophoresis for Bacterial Characterization and Trapping." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51662.
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This work was focused on the characterization of microparticles with particular emphasis on waterborne pathogens which pose a great health risk to human lives. The goal of this study was to develop microfluidic systems for enhanced characterization and isolation of bioparticles. Insulator-based dielectrophoresis (iDEP) is a promising technique for analyzing, characterizing and isolation of microparticles based on their electrical properties. By employing insulator-based constrictions within the microchannel in combination with microelectrodes within the vicinity of the electrodes, dielectrophoretic performance is enhanced. In this study, three dimensional insulator-based dielectrophoresis devices are fabricated using our in-house developed 3D micromachining technique. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The dielectric properties of bacteria as well as submicron polystyrene beads are discussed and the impact of these results on the future development of iDEP microfluidic systems is explored.Master of Science
12
Marnewick, K., PJ Funston, and KU Karanth. "Evaluating camera trapping as a method for estimating cheetah abundance in ranching areas." Southern African Wildlife Management Association, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000683.
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n order to accurately assess the status of the cheetah Acinonyx jubatus it is necessary
to obtain data on numbers and demographic trends. However, cheetahs are notoriously
difficult to survey because they occur at very low population densities and are often shy and
elusive. In South Africa the problem is further complicated in areas where land is privately
owned, restricting access, with dense bush and cheetahs that are frequently persecuted.
Cheetahs are individually identifiable by their unique spot patterns, making them ideal
candidates for capture–recapture surveys. Photographs of cheetahs were obtained using
four camera traps placed successively at a total of 12 trap locations in areas of known
cheetah activity within a 300 km² area in the Thabazimbi district of the Limpopo Province.
During 10 trapping periods, five different cheetahs were photographed. These results were
used to generate capture histories for each cheetah and the data were analysed using the
capture–recapture software package CAPTURE. Closure tests indicated that the population
was closed (P = 0.056). The Mh model was used to deal with possible heterogeneous capture
probabilities among individual cheetahs. Closure tests did not reject the model assumption
of population closure (P = 0.056).TheMh model produced a capture probability of 0.17 with an
estimate of 6–14 cheetahs (P = 0.95) and a mean population size of seven cheetahs
(S.E. = 1.93). These results are promising and will be improved with employment of more
camera traps and sampling a larger area.
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Yuksek, Nuh Sadi. "Thermally Stimulated Current Observation Of Trapping Centers In Layered Thallium Dichalcogenide Semiconductors." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605303/index.pdf.
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Thermally stimulated current measurements are carried out on as-grown TlGaS2, TlGaSe2 and TlInS2 layered single crystals with the current owing perpendiclar to the c-axis in the wide temperature range of 10-300 K with various heating rates. Experimental evidence is found for the presence of three, two and one trapping centers for TlGaS2 , TlGaSe2 and TlInS2 crystals with activation energies 6, 12 and 2698 and 130
12 meV respectively. We have determined the trap parameters using varous methods of analyis, and these agree well with each other. The retrapping process is negligible for these levels, as confirmed by good agreement between the experimental results and theoretical predictions of the model that assumes slow retrapping. Also the calculated values of the capture cross sections, attempt to escape frequencies and the concentration of the traps are reported.
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Tvingstedt, Kristofer. "Light Trapping and Alternative Electrodes for Organic Photovoltaic Devices." Doctoral thesis, Linköpings universitet, Biomolekylär och Organisk Elektronik, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17229.
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Organic materials, such as conjugated polymers, have emerged as a promising alternative for the production of inexpensive and flexible photovoltaic cells. As conjugated polymers are soluble, liquid based printing techniques enable production on large scale to a price much lower than that for inorganic based solar cells. Present day state of the art conjugated polymer photovoltaic cells are comprised by blends of a semiconducting polymer and a soluble derivative of fullerene molecules. Such bulk heterojunction solar cells now show power conversion efficiencies of up to 4-6%. The quantum efficiency of thin film organic solar cells is however still limited by several processes, of which the most prominent limitations are the comparatively low mobility and the high level of charge recombination. Hence organic cells do not yet perform as well as their more expensive inorganic counterparts. In order to overcome this present drawback of conjugated polymer photovoltaics, efforts are continuously devoted to developing materials or devices with increased absorption or with better charge carrier transporting properties. The latter can be facilitated by increasing the mobility of the pure material or by introducing beneficial morphology to prevent carrier recombination. Minimizing the active layer film thickness is an alternative route to collect more of the generated free charge carriers. However, a minimum film thickness is always required for sufficient photon absorption. A further limitation for low cost large scale production has been the dependence on expensive transparent electrodes such as indium tin oxide. The development of cheaper electrodes compatible with fast processing is therefore of high importance. The primary aim of this work has been to increase the absorption in solar cells made from thin films of organic materials. Device construction, deploying new geometries, and evaluation of different methods to provide for light trapping and photon recycling have been strived for. Different routes to construct and incorporate light trapping structures that enable higher photon absorption in a thinner film are presented. By recycling the reflected photons and enhancing the optical path length within a thinner cell, the absorption rate, as well as the collection of more charge carriers, is provided for. Attempts have been performed by utilizing a range of different structures with feature sizes ranging from nanometers up to centimeters. Surface plasmons, Lambertian scatterers, micro lenses, tandem cells as well as larger folded cell structures have been evaluated. Naturally, some of these methods have turned out to be more successful than others. From this work it can nevertheless be concluded that proper light trapping, in thin films of organic materials for photovoltaic energy conversion, is a technique capable of improving the cell performance. In addition to the study of light trapping, two new alternative electrodes for polymer photovoltaic devices are suggested and evaluated.
15
Ashok, Praveen Cheriyan. "Integration methods for enhanced trapping and spectroscopy in optofluidics." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2546.
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“Lab on a Chip” technologies have revolutionized the field of bio-chemical analytics. The crucial role of optical techniques in this revolution resulted in the emergence of a field by itself, which is popularly termed as “optofluidics”. The miniaturization and integration of the optical parts in the majority of optofluidic devices however still remains a technical challenge. The works described in this thesis focuses on developing integration methods to combine various optical techniques with microfluidics in an alignment-free geometry, which could lead to the development of portable analytical devices, suitable for field applications. The integration approach was applied to implement an alignment-free optofluidic chip for optical chromatography; a passive optical fractionation technique fractionation for cells or colloids. This system was realized by embedding large mode area photonic crystal fiber into a microfluidic chip to achieve on-chip laser beam delivery. Another study on passive sorting envisages an optofluidic device for passive sorting of cells using an optical potential energy landscape, generated using an acousto-optic deflector based optical trapping system. On the analytical side, an optofluidic chip with fiber based microfluidic Raman spectroscopy was realized for bio-chemical analysis. A completely alignment-free optofluidic device was realized for rapid bio-chemical analysis in the first generation by embedding a novel split Raman probe into a microfluidic chip. The second generation development of this approach enabled further miniaturization into true microfluidic dimensions through a technique, termed Waveguide Confined Raman Spectroscopy (WCRS). The abilities of WCRS for online process monitoring in a microreactor and for probing microdroplets were explored. Further enhanced detection sensitivity of WCRS with the implementation of wavelength modulation based fluorescent suppression technique was demonstrated. WCRS based microfluidic devices can be an optofluidic analogue to fiber Raman probes when it comes to bio-chemical analysis. This allows faster chemical analysis with reduced required sample volume, without any special sample preparation stage which was demonstrated by analyzing and classifying various brands of Scotch whiskies using this device. The results from this study also show that, along with Raman spectroscopic information, WCRS picks up the fluorescence information as well, which might enhance the classification efficiency. A novel microfabrication method for fabricating polymer microlensed fibers is also discussed. The microlensed fiber, fabricated with this technique, was combined with a microfluidic gene delivery system to achieve an integrated system for optical transfection with localized gene delivery.
16
Park, Yoonseok. "Light trapping substrates and electrodes for flexible organic photovoltaics." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-219686.
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Organic solar cells are one of the most promising candidates for future solar power generation. They are thin and lightweight with several additional advantages such as scalability, environmental sustainability and low cost for processing and installation. However, the low charge carrier mobility of the absorbing material for organic solar cells requires thin absorber layers, limiting photon harvesting and the overall power conversion efficiency. Several attempts, e.g., periodically patterned structures and scattering layers have been tried to enhance the absorption of thin-film solar cells as light trapping elements. However, much effort is required to introduce light trapping structures to conventional rigid metal oxide electrodes and glass substrate. For instance, almost 13 hours are required to fabricate micro structures of 1 m2 area on glass, in contrast, 1 minute on PET using a same laser set-up and an additional scattering layers are demanded for providing light trapping effects to solar cells. In the last years, flexibility is emerging as the one of the major advantages of organic solar cells. To realize flexibility of solar cells, the classically used glass substrates and ITO electrodes are too brittle. Therefore, polymer materials are promising candidates to replace them as flexible electrodes and substrates. In this thesis, the highly transparent conducting polymer, PEDOT:PSS and PET equipped with an AlOx encapsulation layer are used as electrode and substrate, respectively. Besides the flexibility, additional light trapping elements, e.g. scattering particles, nano- and microstructures can be easily applied to the polymer materials since they have the potential for easier shaping and processing. In this study, we apply different light trapping and in-coupling approaches to organic solar cells. First, PET substrates are structured with a direct laser interference patterning system, which is a powerful and scalable one-step technique for patterning polymers. Almost 80 % of the light is diffracted by these patterned PET substrates and thereby the light path in the absorption layer is increased. Optical display films, commercially developed to be used as back light units of liquid crystal displays are also examined as light trapping substrates and exhibit similar enhancement as patterned PET. Moreover, since PEDOT:PSS is prepared by a solution-based process, TiO2 nanoparticles are added as light scattering elements to the PEDOT:PSS electrodes. Consequently, those electrodes provide a dual function as electrical contact and light trapping element. Finally, 2- or 3-dimensional nanostructures are printed by a nano-imprinting technique onto the surface of PEDOT:PSS with PDMS stamps. By controlling the temperature and the time of PEDOT:PSS during an annealing step, nanostructures are transferred from PDMS masks to PEDOT:PSS. To evaluate the effects of light trapping for all above mentioned approaches, flexible organic solar cells are produced by vacuum evaporation using blends of DCV5T-Me and C60 as absorber layer. The substrates are optically characterized using UV-vis spectrometer and goniometer measurements. The topography of the samples is measured by atomic force microscopy, scanning microscopy and optical microscopy. Bending tests with various radii are performed to test the flexibility of the substrates. In summary, light trapping effects are successfully implemented in the electrodes and substrates for OPVs, giving efficiency improvements of up to 16 %. The light trapping mechanisms in our approaches are extensively discussed in this thesisOrganische Photovoltaik ist einer der vielversprechendsten Kandidaten für die zukünftige Solarstromgewinnung auf flexiblen Substraten. Um diese Flexibilität zu ermöglichen, sind herkömliche Glassubstrate mit ITO-Elektroden zu spröde. Ein vielversprechender Kandidat, um sowohl flexible Elektroden als auch flexible Substrate herzustellen, sind Polymere, da diese sehr biegsam und leicht zu verarbeiten sind. Deshalb wird in dieser Arbeit das hoch transparente, leitfähige Polymer PEDOT:PSS als Elektrode und PET (mit einer AlOx Verkapselungsschicht) als Substrat untersucht. Aufgrund der guten Prozessierbarkeit der Polymere konnten wir zusätzlich zu den eigentlichen Funktionen des Substrates und der Elektrode noch den Mechanismus des Lichteinfangs hinzufügen. Zusätzlich zu ihrer Flexibilität haben organische Solarzellen noch weitere Vorteile: sie sind dünn, leicht, skalierbar und verursachen vergleichsweise geringe Kosten für Herstellung und Installation. Ein Nachteil organischer Solarzellen ist die vergleichsweise geringe Ladungsträgerbeweglichkeit der Absorbermaterialien, welche oft die Schichtdicke der Absorbermaterialien begrenzt. Dies hat weniger absorbierte Photonen, weniger Stromdichte und somit einen geringeren Wirkungsgrad zur Folge. In den letzten Jahren wurden periodisch strukturierte Substrate und streuende Schichten als Lichteinfangelemente eingesetzt, um den Wirkungsgrad organischer Solarzellen mit dünnen Absorberschichten zu erhöhen. Gestaltungsregeln für solche Lichteinfangelemente sind noch weitestgehend unbekannt. Im Rahmen dieser Arbeit strukturieren wir PET Substrate mit einem direkten Laserinterferenzsystem, welches ein leistungsfähiges, skalierbares Einschrittverfahren zur Polymerstrukturierung ist. Da PEDOT:PSS aus der Lösung prozessiert wird, können wir weiterhin Nanopartikel hinzufügen, die der Elektrode zusätzlich noch lichtstreuende Eigenschaften geben. Außerdem können 2- bzw. 3-dimensionale Nanostrukturen leicht mithilfe einer Stempeltechnik eingeprägt werden. Um die Effekte des Lichteinfangs, welcher durch die oben genannten Methoden erzeugt wird, zu untersuchen, werden flexible organische Solarzellen mittels Vakuumverdampfung prozessiert. DCV5T-Me und C60 bilden dabei die photoaktive Schicht. Somit werden die Licht fangenden Eigenschaften dieser flexiblen Solarzellen ausgenutzt und ausführlich in der Arbeit diskutiert
17
Banakar, Mehdi. "Sub-micron texturing for photovoltaic antireflection and light-trapping." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/383004/.
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The photovoltaic solar energy industry has experienced substantial growth over the last few years and this growth has led to manufacturing cost reductions that have brought solar energy to grid parity in many parts of the world. Grid parity will inevitably lead to further expansions of the industry as uptake of the technology will no longer be subsidy driven. As the industry continues to mature, scientific and technological innovations that reduce the $/Watt cost of solar energy will allow companies to gain a competitive edge and increasingly ensure that solar energy can become affordable for communities in the developing world. Development of antireflection and light trapping schemes that can help increase efficiency or else decrease material requirements of solar cells are one way that science and technology might contribute to the drive for reduced $/Watt. Three novel types of sub-micron scale texturing are examined in this work. In each, advanced nanofabrication techniques, specialist characterisation apparatus and complex simulation software are used to gain insight into these new structures. Sub-micron inverted pyramid structures formed in silicon by a combination of e-beam lithography and a Potassium hydroxide (KOH) etch are found to have a significant antireflective effect. The best structures are found to have a weighted reflectance of 10% when the periodicity is 700 nm, when the spacing between pyramids is as small as possible, and when a thin layer of SiO2 is added as a antireflection coating. Further reduction of reflectance is only possible by increasing feature size and there appear are no low-reflection sweet spots in sub-micron designs. Mie Resonator structures were formed in silicon by a combination of e-beam lithography, lift-off and reactive ion etching through a metal hard mask. We have found that the best structures, consisting of arrays of silicon cylinders with diameters of 180nm, heights of 95 nm and periodicity of 500 nm, have weighted reflectance as low as 5.5% and, in fact, better than silicon moth-eye structures. Mie resonator structures seem to provide a very promising antireflective surface that also confer light-trapping effects. The structures be easier to fabricate that moth-eye structures while significantly reducing the silicon wastage associated with micron-scale inverted pyramid technologies that are conventionally used. Finally, we have carried out an investigation of a self-forming silicon nanowire surfaces that can reduce weighted reflectance to values as low as 0.05% although these are impressive antireflective surfaces that might find application in some optoelectronic systems where scattered light should be reduced, we have concluded that the nanowire structures are unlikely to help solar cell design as increased surface area and surface contamination and damage is likely to greatly increase surface recombination and limit device efficiencies. In conclusion, it is clear that Mie Resonator structures are amongst the most promising antireflective surfaces and further studies should focus on optimisation of light-trapping and device integration of these structures. The use of Mie resonator structures might eventually allow Crystalline Silicon (C-Si) wafer thickness to decrease to a few microns without reduction in device efficiency.
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Hum, Eddy N. (Eddy Ning) Carleton University Dissertation Engineering Electrical. "Burst-trapping codes for the land mobile data channel." Ottawa, 1988.
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Muckley, Eric S. "Constructing a magneto-optical trap for cold atom trapping /." Click here to view, 2009. http://digitalcommons.calpoly.edu/physsp/2.
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Thesis (B.S.)--California Polytechnic State University, 2009.Project advisor: Katharina Gillen. Title from PDF title page; viewed on Jan. 14, 2010. Includes bibliographical references. Also available on microfiche.
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Negoita, Madalina. "Domain walls in ferromagnetic nanowires for atom trapping applications." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5140/.
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In this thesis I demonstrate that is possible to transport DWs in ferromagnetic nanowires at arbitrarily low velocities. The approach used here is to confine the DWs into geometrically defined energy minima. DWs are transported by applying a rotating field. The velocity at which the DWs travel depends on the ring radius and the frequency of the applied field. Several rings of different widths were analysed under different applied fields and a range of frequencies of the applied field. The results show that the walls are pinned by defects as they travel in the ring. The defects cause the walls to lag behind the vector field. The lag depends strongly on the field strength, so that at higher fields the walls move smoother. On the other hand, a high field would cant the magnetic moments in the ring and widen the DW. Also the frequency of the applied field influences the local velocity when DWs depin from defects and a method of calculating this local velocity was described. The analysis is extended further to a structure which allows linear transport of DWs still at low velocities. The structure is based on the analysis presented for rings, where rotating fields drive the DWs in the structure. By applying successive clockwise and anticlockwise fields, the walls travel through half-rings over large distances. Finally, multi-ring structures are analysed to study the influence of large periodic pinning of DWs across a correlated system. This is relevant in the light of interacting magnetic systems as well as to DW atom trapping as a means of stimulating collisional atomic interactions. Neighbour rings in this kind of structures can introduce DWs into other rings through junctions. Also, due to pinning, DWs might also annihilate. In low fields, each field cycle the number of DWs can be different.
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Can, Ozgun Emre. "Camera Trapping Large Mammals In Yenice Forest Habitats: A Feasibility Study For Camera Trapping Large Mammals In Yenice Forests, Turkey." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609974/index.pdf.
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Widely applicable, quantitative field methods are needed to gather wildlife data for conservation and management initiatives in Turkey. In order to evaluate the use of camera traps in forest habitats of Turkey, we conducted a 5 phase camera trap survey by using 16 passive infrared-triggered cameras with a total sampling effort of 1200 camera trap days in Yaylacik Research Forest, a 50 km2 forest patch of Yenice Forest in Karabük during January-May 2006. The camera trap survey confirmed the presence of grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), red fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) in the study area. The camera trap survey also revealed the presence of jackal (Canis aureus) and brown hare (Lepus europaeus), whose presence were not known by people living and working in the area. Contrary to the local belief, neither camera trapping survey nor ground survey confirmed the presence of lynx (Lynx lynx) in Yaylacik Research Forest. The wolf was observed to be crepuscular and the wildcat showed a diurnal activity pattern. Wildcat seemed to avoid other carnivores spatially and temporally. Simulation studies suggested that camera trap surveys should last 14 days for wolf, 13 days for wildcat, 10 days for pine marten, and 11 days for roe deer, while it is advisable to conduct longer surveys, probably 15-20 days, for wild boar, red fox and brown bears. The estimated population size for wildcat was 9 (SE=2.28227) with 95% confidence interval of 9 to 25 in the study area. A minimum of 6 brown bears were present in the study area. Our study indicated that the local knowledge about the presence of wildlife should be considered by researchers, but it cannot replace scientific surveys conducted by field biologists. This study was the first attempt to assess the presence, relative abundance, activity patterns and diversity of multiple mammal species by the use of camera trapping methodology in Turkey. The results suggest that camera trap surveys have the potential for gathering wildlife data at larger scales in Turkey, where information gap on large mammals is an obstacle for effective management and conservation of mammals.
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Blight, S. R. "Surface and bulk traps in materials and devices for GaAs integrated circuits." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383250.
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Mahamdeh, Mohammed. "High Resolution Optical Tweezers for Biological Studies." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-81918.
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In the past decades, numerous single-molecule techniques have been developed to investigate individual bio-molecules and cellular machines. While a lot is known about the structure, localization, and interaction partners of such molecules, much less is known about their mechanical properties. To investigate the weak, non-covalent interactions that give rise to the mechanics of and between proteins, an instrument capable of resolving sub-nanometer displacements and piconewton forces is necessary. One of the most prominent biophysical tool with such capabilities is an optical tweezers.
Optical tweezers is a non-invasive all-optical technique in which typically a dielectric microsphere is held by a tightly focused laser beam. This microsphere acts like a microscopic, three-dimensional spring and is used as a handle to study the biological molecule of interest. By interferometric detection methods, the resolution of optical tweezers can be in the picometer range on millisecond time scales. However, on a time scale of seconds—at which many biological reactions take place—instrumental noise such as thermal drift often limits the resolution to a few nanometers. Such a resolution is insufficient to resolve, for example, the ångstrom-level, stepwise translocation of DNA-binding enzymes corresponding to distances between single basepairs of their substrate. To reduce drift and noise, differential measurements, feedback-based drift stabilization techniques, and ‘levitated’ experiments have been developed. Such methods have the drawback of complicated and expensive experimental equipment often coupled to a reduced throughput of experiments due to a complex and serial assembly of the molecular components of the experiments.
We developed a high-resolution optical tweezers apparatus capable of resolving distances on the ångstrom-level over a time range of milliseconds to 10s of seconds in surface-coupled assays. Surface-coupled assays allow for a higher throughput because the molecular components are assembled in a parallel fashion on many probes. The high resolution was a collective result of a number of simple, easy-to-implement, and cost-efficient noise reduction solutions. In particular, we reduced thermal drift by implementing a temperature feedback system with millikelvin precision—a convenient solution for biological experiments since it minimizes drift in addition to enabling the control and stabilization of the experiment’s temperature. Furthermore, we found that expanding the laser beam to a size smaller than the objective’s exit pupil optimized the amount of laser power utilized in generating the trapping forces. With lower powers, biological samples are less susceptible to photo-damage or, vice versa, with the same laser power, higher trapping forces can be achieved. With motorized and automated procedures, our instrument is optimized for high-resolution, high-throughput surface-coupled experiments probing the mechanics of individual biomolecules. In the future, the combination of this setup with single-molecule fluorescence, super-resolution microscopy or torque detection will open up new possibilities for investigating the nanomechanics of biomolecules.
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Planjery, Shiva Kumar. "Iterative decoding beyond belief propagation for low-density parity-check codes." Thesis, Cergy-Pontoise, 2012. http://www.theses.fr/2012CERG0618.
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Les codes Low-Density Parity-Check (LDPC) sont au coeur de larecherche des codes correcteurs d'erreurs en raison de leur excellenteperformance de décodage en utilisant un algorithme de décodageitératif de type propagation de croyances (Belief Propagation - BP).Cet algorithme utilise la représentation graphique d'un code, ditgraphe de Tanner, et calcule les fonctions marginales sur le graphe.Même si l'inférence calculée n'est exacte que sur un graphe acyclique(arbre), l'algorithme BP estime de manière très proche les marginalessur les graphes cycliques, et les codes LDPC peuvent asymptotiquementapprocher la capacité de Shannon avec cet algorithme.Cependant, sur des codes de longueurs finies dont la représentationgraphique contient des cycles, l'algorithme BP est sous-optimal etdonne lieu à l'apparition du phénomène dit de plancher d'erreur. Leplancher d'erreur se manifeste par la dégradation soudaine de la pentedu taux d'erreur dans la zone de fort rapport signal à bruit où lesstructures néfastes au décodage sont connues en termes de TrappingSets présents dans le graphe de Tanner du code, entraînant un échec dudécodage. De plus, les effets de la quantification introduite parl'implémentation en hardware de l'algorithme BP peuvent amplifier ceproblème de plancher d'erreur.Dans cette thèse nous introduisons un nouveau paradigme pour ledécodage itératif à précision finie des codes LDPC sur le canalbinaire symétrique. Ces nouveaux décodeurs, appelés décodeursitératifs à alphabet fini (Finite Alphabet Iterative Decoders – FAID)pour préciser que les messages appartiennent à un alphabet fini, sontcapables de surpasser l'algorithme BP dans la région du plancherd'erreur. Les messages échangés par les FAID ne sont pas desprobabilités ou vraisemblances quantifiées, et les fonctions de miseà jour des noeuds de variable ne copient en rien le décodage par BP cequi contraste avec les décodeurs BP quantifiés traditionnels. Eneffet, les fonctions de mise à jour sont de simples tables de véritéconçues pour assurer une plus grande capacité de correction d'erreuren utilisant la connaissance de topologies potentiellement néfastes audécodage présentes dans un code donné. Nous montrons que sur demultiples codes ayant un poids colonne de trois, il existe des FAIDutilisant 3 bits de précision pouvant surpasser l'algorithme BP(implémenté en précision flottante) dans la zone de plancher d'erreursans aucun compromis dans la latence de décodage. C'est pourquoi lesFAID obtiennent des performances supérieures comparées au BP avecseulement une fraction de sa complexité.Par ailleurs, nous proposons dans cette thèse une décimation amélioréedes FAID pour les codes LDPC dans le traitement de la mise à jour desnoeuds de variable. La décimation implique de fixer certains bits ducode à une valeur particulière pendant le décodage et peut réduire demanière significative le nombre d'itérations requises pour corriger uncertain nombre d'erreurs fixé tout en maintenant de bonnesperformances d'un FAID, le rendant plus à même d'être analysé. Nousillustrons cette technique pour des FAID utilisant 3 bits de précisioncodes de poids colonne trois. Nous montrons également comment cettedécimation peut être utilisée de manière adaptative pour améliorer lescapacités de correction d'erreur des FAID. Le nouveau modèle proposéde décimation adaptative a, certes, une complexité un peu plus élevée,mais améliore significativement la pente du plancher d'erreur pour unFAID donné. Sur certains codes à haut rendement, nous montrons que ladécimation adaptative des FAID permet d'atteindre des capacités decorrection d'erreur proches de la limite théorique du décodage au sensdu maximum de vraisemblanceAt the heart of modern coding theory lies the fact that low-density parity-check (LDPC) codes can be efficiently decoded by message-passing algorithms which are traditionally based on the belief propagation (BP) algorithm. The BP algorithm operates on a graphical model of a code known as the Tanner graph, and computes marginals of functions on the graph. While inference using BP is exact only on loop-free graphs (trees), the BP still provides surprisingly close approximations to exact marginals on loopy graphs, and LDPC codes can asymptotically approach Shannon's capacity under BP decoding.However, on finite-length codes whose corresponding graphs are loopy, BP is sub-optimal and therefore gives rise to the error floor phenomenon. The error floor is an abrupt degradation in the slope of the error-rate performance of the code in the high signal-to-noise regime, where certain harmful structures generically termed as trapping sets present in the Tanner graph of the code, cause the decoder to fail. Moreover, the effects of finite precision that are introduced during hardware realizations of BP can further contribute to the error floor problem.In this dissertation, we introduce a new paradigm for finite precision iterative decoding of LDPC codes over the Binary Symmetric channel (BSC). These novel decoders, referred to as finite alphabet iterative decoders (FAIDs) to signify that the message values belong to a finite alphabet, are capable of surpassing the BP in the error floor region. The messages propagated by FAIDs are not quantized probabilities or log-likelihoods, and the variable node update functions do not mimic the BP decoder, which is in contrast to traditional quantized BP decoders. Rather, the update functions are simple maps designed to ensure a higher guaranteed error correction capability by using the knowledge of potentially harmful topologies that could be present in a given code. We show that on several column-weight-three codes of practical interest, there exist 3-bit precision FAIDs that can surpass the BP (floating-point) in the error floor without any compromise in decoding latency. Hence, they are able to achieve a superior performance compared to BP with only a fraction of its complexity.Additionally in this dissertation, we propose decimation-enhanced FAIDs for LDPC codes, where the technique of decimation is incorporated into the variable node update function of FAIDs. Decimation, which involves fixing certain bits of the code to a particular value during the decoding process, can significantly reduce the number of iterations required to correct a fixed number of errors while maintaining the good performance of a FAID, thereby making such decoders more amenable to analysis. We illustrate this for 3-bit precision FAIDs on column-weight-three codes. We also show how decimation can be used adaptively to further enhance the guaranteed error correction capability of FAIDs that are already good on a given code. The new adaptive decimation scheme proposed has marginally added complexity but can significantly improve the slope of the error floor performance of a particular FAID. On certain high-rate column-weight-three codes of practical interest, we show that adaptive decimation-enhanced FAIDs can achieve a guaranteed error-correction capability that is close to the theoretical limit achieved by maximum-likelihood decoding
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Simsek, Senem. "DEVELOPMENT OF TRAPPING STYLE CASSETTES FOR NEW GENE TARGETING STRATEGIES." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1193679015297-95667.
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Because of shared physiological, anatomical and metabolical features with humans, mice have served for a long time as mammalian disease models. In particular, these last ten years have been the golden age for this favoured model animal. Human and mouse genome projects show that there is 95% genome homology. Spurred by this fact, research attention has shifted from reading these sequences to deciphering the functions of these genes. The 1980s saw the remarkable achievement of homologous recombination in mammalian cell culture systems. Later in the 1990s, innovative gene trapping strategies were developed to enabled random mutagenesis. Today, the goal is to generate more versatile tools to avoid limitations posed by these earlier mutagenesis strategies. Many public and private research centers have united with the aim of mutating all mouse genes. In order to achieve this mutagenesis, the first requirement is a set of practical and efficient viral or plasmid based vectors that can be used globally in the genome. This will be aided by advances in understanding of biological events such as gene transcription, recombination, and embryonic stem cell cycle. In addition, technical improvements such as vector development, precise cell culture assay, and recombinant DNA delivery will also be important. The vector design work in this PhD thesis encompasses 0.00001 % ofthese efforts but may to out to be highly relevant...
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Rogachevskiy, Andrey Valerievich. "Production and trapping of Na isopes for [beta]-decay studies." [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn//303494689.
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Brownnutt, Michael. "88Sr+ ion trapping techniques and technologies for quantum information processing." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445167.
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Vangeleyn, Matthieu. "Atom trapping in non-trivial geometries for micro-fabrication applications." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=15575.
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Bradshaw, N. M. "Studies of adsorbent trapping and diffusion methods for environmental analysis." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636143.
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Chapter one introduces the historical background, development and need for monitoring techniques utilising absorbent tube sampling methods and highlights the rapid increase in environmental awareness that has occurred as technology has advanced. A short summary covering the sources of volatile organic compounds (VOCs) is included. Chapter two presents a synopsis of the experimental methods and theory associated with adsorbent tube sampling and analysis. The application of both passive and active sampling techniques has been discussed with the emphasis on maintaining sampling and analytical integrity. Chapter three covers the key sources of error in both sampling and analysis and defines statistical terms that are used in analytical science. The measurement and calculation of tube dimensions, diffusion coefficients, mass uptake rates, limit of detection and quantification are presented. Chapter four outlines the findings from an inter-laboratory calibration exercise to investigate external calibration methods at low nanogram levels. The use of certified reference materials and preparation of standards is discussed. Chapters five and six assess the likely errors to be encountered when using passive sampling techniques for long term environmental monitoring, and cover aspects of sampling accuracy, bias and precision. Particular attention is devoted to assessing changes in the mass uptake rate and back diffusion during passive sampling. Chapters seven to ten detail research related to the application of adsorbent tube trapping for the sampling and analysis of VOCs in soil gases. Work has focused on enhancing both the qualitative and quantitative information that can be obtained from soil gas surveys by the use of heated sampling techniques to increase the recovery of less volatile compounds. The feasibility of an indoor test facility to simulate soil and soil gas contamination is also discussed.
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Chu, Hung, and 朱紅. "Investigation of a transposon-assisted exon trapping system for Arabidopsis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43703884.
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Guardado-Sanchez, Elmer. "A laser system for trapping and cooling of ⁶Li atoms." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100336.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-60).
In this thesis, I designed and built a laser system for the trapping and cooling of ⁶Li atoms. The thesis starts explaining a theoretical background of the necessary laser frequencies for the realization of a Zeeman Slower and a 3D MOT. Next it describes the design of the laser system that makes use of a Raman Fiber Amplifier coupled with a Frequency Doubling Cavity and shows the finalized setup. Finally, the thesis delves into the topic of Modulation Transfer Spectroscopy which was used to lock the laser to the D₂ line transition of ⁶Li and shows the spectroscopy setup built for the laser system.
by Elmer Guardado-Sanchez.
S.B.
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Levonian, David (David S. ). "A Cavity-stabilized diode laser for dipole trapping of ytterbium." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/105998.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 99-103).
Bad-cavity lasers using a gain medium with a narrower linewidth than the laser cavity have the potential to achieve very narrow linewidths and extremely long coherence times. Such lasers could serve as active frequency standards or enable very-long-baseline interferometric telescopes at optical frequencies. The 6s6p³P₀ to 6s²¹S₀ ground state transition in ¹⁷¹Yb is a promising candidate for the gain medium of a bad-cavity laser due to its 44 mHz linewidth. For ytterbium to be used efficiently as a gain medium, its inhomogeneous broadening must be suppressed to a level lower than the linewidth of its gain transition. In this thesis, I design, implement, and characterize an optical lattice trap for ytterbium atoms. The trap consists of a diode laser which is frequency stabilized to an adjustable-length cavity where the ytterbium atoms are trapped. The length of this cavity is then locked by comparison of the laser frequency to a stable reference cavity. The resulting standing wave has high enough intensity that the recoil energy of the gain transition is smaller than the energy spacing between motional modes of the trapped atoms. This situation is known as the Lamb-Dicke regime and means that there is an absence of recoil broadening. The large spacing between motional modes of the trap also enables sideband resolved cooling of the atoms, which allows cooling to temperatures of 3 [mu]K, near the ground state of the trapping potential. Additionally, if the wavelength of the optical lattice is chosen to be at the magic wavelength for ytterbium, where the relative AC Stark shift for the two levels of the gain transition is zero to first order, there is no broadening due to varying intensity in the trap. Since the Doppler effect, recoil broadening and the AC Stark shift are the main sources of inhomogeneous broadening, this trapping scheme is expected to suppress inhomogeneous broadening to a level of 1 Hz.
by David Levonian.
M. Eng.
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Wang, Ying-Chih 1977. "Electrokinetic trapping of biomolecules : novel nanofluidic devices for proteomic applications." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40358.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 135-141).
Sample preparation has long been the most important and costly process in bioanalyses. Conventional identification methods involve multiple purification steps combined with mass spectrometry or immunosensing. While well-developed and widely utilized, these methods require extensive human labor and exhibit limited resolving power for low abundance analytes. Due to the shear complexity and abundance variation of biosamples, rapid and ultra-sensitive diagnostic measurements of disease markers are still out of reach. To address this issue, we developed a novel nanofluidic concentrator, utilizing the unique concentration polarization effect of sub 50 nm nanofluidic filters. With the distinct ionic and molecular interaction at the nanoscale, nanofluidic systems can potentially outperform current sample preparation and molecular detection techniques. Aiming to investigate and expand the applications of these techniques, this thesis work involves the design and development of a highly efficient nanofluidic preconcentrator, which can achieve a million fold detectability enhancements without complex buffer arrangements. This thesis also includes an integrated preconcentration-immunosensing device.
(cont.) By manipulating analyte concentrations, this integrated device not only increases the detection sensitivity, but also expands the dynamic range of given antibody-antigen couples. In addition, we also investigated the ion transfer at the micro-/nano-fluidic interface. Depending on the strength of the applied electric field across the nanochannel array, various phenomena such as concentration polarization, charge depletion, and nonlinear electrokinetic flows in the adjacent microfluidic channel can be observed and studied in situ by fluorescent microscopy. In summary, the nanofluidic concentrator we developed in this thesis facilitates sample preparation and detection of biomolecules from complex biological matrices and facilitates a further understanding of nanoscale molecular/fluid/ion transport phenomena by providing a well-controlled experimental platform.
by Ying-Chih Wang.
Ph.D.
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Wang, Lynn (Lynn H. ). "Development of a heating stage for an optical trapping microscope." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36687.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 24-25).
The Lang Laboratory specializes in the study of biological systems through research using optical tweezers. Currently, experiments involving force and position manipulations of cellular molecules take place at room temperature. Experiments with these molecules have the potential to yield more information about biological systems were these experiments performed at the temperature at which the molecules naturally operate. Since the microscopes in the laboratory are geared with sensitive lasers, mirrors, and detectors that make up the optical traps, a custom designed microscope stage heater is necessary to execute research at body temperature (37°C). A custom temperature controller, equipped with controller unit and slide heating aluminum plates, is built to warm the slide sample to and maintain it at 37°C without interfering with the operation of the specified microscope.
by Lynn Wang.
S.B.
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Voldman, Joel. "A microfabricated dielectrophoretic trapping array for cell-based biological assays." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8590.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 143-152).
This thesis presents the development of a small planar array of microfabricated traps for holding single cells and performing assays on them. The traps use the phenomenon of dielectrophoresis-the force on polarizable bodies in a non-uniform electric field-to make potential energy wells. These potential energy wells are electrically switchable, arrayable, and amenable to batch fabrication. The trapping arrays have potential use as a cytometer for monitoring the dynamics of populations of single cells and then sorting those cells based upon those dynamics. To design such traps, I have developed a modeling environment that can absolutely predict the ability of DEP-based traps to hold particles against liquid flows, which are the dominant destabilizing force in these systems. I have used the common easy-to-fabricate planar quadrupole trap to verify the accuracy of these modeling tools, and in the process determined why planar quadrupole traps behave as they do. I next used the modeling tools to design an improved quadrupole trap-the extruded quadrupole-that has the potential to hold particles lOx-100x stronger. The extruded quadrupole trap consists of a set of microfabricated gold posts arranged in a trapezoidal fashion, to ease trap loading, and includes metal substrate shunts to improve performance. The fabrication process for small arrays of these traps uses electroplating of gold into an SU-8 mold to achieve the required geometries. The final section of the thesis details experiments using small arrays of these extruded quadrupole traps. Experiments were performed with beads to verify the strong nature of the trap and then with cells to demonstrate qualitative operation of the arrays and the ability to perform dynamic fluorescent assays on multiple single cells followed by sorting. The technology is now well poised to enable the development of biological assays that are currently unavailable.
by Joel Voldman.
Ph.D.
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Matthias, Jonas [Verfasser]. "Magnetic trapping for an atom-chip-based gravimeter / Jonas Matthias." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1221270087/34.
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Sesuraj, Rufina. "Plasmonic mirror for light-trapping in thin film solar cells." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366663/.
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Microcrystalline silicon solar cells require an enhanced absorption of photons in the near-bandgap region between 700-1150nm. Conventional textured mirrors scatter light and increase the path length of photons in the absorber by total internal reflection. However, these mirrors exhibit a high surface roughness which degrades the performance of the microcrystalline silicon device. An alternative solution is to use metal nanoparticles with low surface roughness to scatter light. An illuminated metal nanoparticle exhibits a resonant or plasmonic excitation which can be tuned to enable a strong scattering of light. This work aims to develop an efficient near-infrared light-scattering system using randomly arranged metal nanoparticles near a mirror. Situating the nanoparticles at the rear of the solar cell helps to target weakly absorbed photons and eliminate out-coupling losses by the inclusion of a rear mirror. Simulation results show that the electric field driving the plasmonic resonance can be tuned with particle-mirror separation distance. The plasmonic scattering is maximised when the peak of the driving field intensity coincides with the intrinsic resonance of the nanoparticle. An e-beam lithography process was developed to fabricate a pseudo-random array of Ag nanodiscs near a Ag mirror. The optimized plasmonic mirror, with 6% coverage of 200nm Ag discs, shows higher diffusive reflectivity than a conventional textured mirror in the near-infrared region, over a broad angular range. Unlike a mirror with self-organised Ag islands, the mirror with Ag nanodiscs exhibits a low surface roughness of 13.5nm and low broadband absorption losses of around 10%. An 8.20% efficient thin n-i-p μc-Si:H solar cell, with the plasmonic mirror integrated at the rear, has been successfully fabricated. The optimised plasmonic solar cell showed an increase of 2.3mA in the short-circuit current density (Jsc), 6mV in the open-circuit voltage (Voc) and 0.97% in the efficiency (η), when compared to the planar cell counterpart with no nanodiscs. The low surface roughness of the plasmonic mirror ensures no degradation in the electrical quality of the μc-Si:H layer – this is also confirmed by the constant value of the fill factor (FF). The increase in Jsc is demonstrated to be mainly due to optical absorption enhancement in the near-infrared region as a result of plasmonic scattering, by detailed calculation of the exact photogenerated current in the plasmonic and planar devices, for the 700-1150nm wavelength range.
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Cooper, Nathan. "Novel techniques for the trapping and manipulation of ultracold atoms." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/368606/.
Full textAbstract:
We describe several novel techniques for the optical trapping of ultracold atoms and for the production of wavelength-stabilised, coherent light at the frequencies required for use in atomic physics experiments. The greater part of this thesis deals with work towards the creation of regular arrays of microscopic optical dipole traps formed at the foci of truncated spherical cavities in a metallic film, in which the inter-site spacing can be set anywhere between one and several hundred micrometers. Arrays of such cavities are synthesised and structurally characterised via optical and electron microscopy, and numerical simulations of the light intensity distribution near the foci of such cavities under normal illumination are used to confirm their suitability for dipole trap production. A method for the construction of arrays of magneto-optical traps based on such structures is proposed and theoretically examined, and some preliminary experimental work towards the synthesis of the required microstructures is also described. Possible approaches to the loading of such traps and the imaging of the atoms contained therein are discussed - experimental work towards ballistic atom transfer from a specialised form of magneto-optical trap that can be formed close to a microstructured surface is carried out, and the efficacy of wavelength-selective fluorescence imaging as a means of reducing the effects of background scatter from the surface is experimentally demonstrated. Further work described herein includes the proposal and experimental demonstration of two novel techniques for the removal of the carrier wave from a phase-modulated laser beam, one of which is based on a fiber-optic Mach-Zehnder interferometer that is shown to be an effective device for splitting or combining beams of nearly equal frequencies. A spontaneous-force based atom trapping mechanism that does not rely on the use of a magnetic field, but rather on spatially-dependent optical pumping between different metastable atomic states, is also proposed, and a proof of principle experiment is carried out to demonstrate the validity of the suggested mechanism. We find that this trapping scheme allows the spatial dependence of the trapping force to be tailored with a greater degree of exibility than is usually possible with magneto-optical trapping, and that it is also capable of producing traps with stronger spring constants than are typically achievable with magneto-optical trapping under realistic experimental constraints.
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Chu, Hung. "Investigation of a transposon-assisted exon trapping system for Arabidopsis." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43703884.
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Vieira, Gregory Butler. "Patterned Magnetic Structures for Micro-/Nanoparticle and Cell Manipulation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354567338.
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Roberts, Sian Eleri. "Evaluation of new method for identifying genes in cloned human DNA." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388653.
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Kahra, Steffen. "Trapping and cooling of single molecular ions for time resolved experiments." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-128803.
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Schofield, Neil A. "Development of optical trapping for the isolation of environmentally regulated genes." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286012.
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Bradley, Ruth. "Optimisation of Fe3O4 thin films and nanostructures for atom trapping applications." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19747/.
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Thin films and nanostructures of Fe3O4 have been investigated and analysed with the aim of being used for an exciting application where the stray magnetic field from domain walls in nanowires are used to trap ultra-cold atoms. In this thesis, polycrystalline Fe3O4 thin films have been successfully grown on Si using reactive dc magnetron sputtering from a Fe target. It has been shown that by using different growth temperatures produces different iron oxide phases. Fe3O4 was grown at substrate temperatures of 200 – 500 ºC with a mixed iron oxide phase of Fe3O4 & α-Fe2O3 produced at RT & 100 ºC. In contrast to the polycrystalline, granular films on Si, Fe3O4 thin films grown on MgO (100) have been shown to be textured with a smooth surface. However, multiple different surface morphologies have been found for the Fe3O4/MgO films. The coercivity of the Fe3O4 films has a negative trend with the film thickness for both substrates, whereas the grain size (Fe3O4/Si) has a positive trend with both film thickness and growth temperature. Following an annealing treatment of Fe3O4 thin films at 250 ºC the composition of the film was altered to become a mixed iron oxide of Fe3O4 & γ-Fe2O3. Dramatic changes in coercivity have been observed, with a large increase seen for the films on Si and negligible change seen for the films on MgO. However, a significant decrease in coercivity has been seen for a smooth film on MgO and the increase in coercivity on Si is dependent on the presence of Fe3O4 regions amongst the mixed iron oxide. Nanostructures of Fe3O4 were created from thin films on Si & MgO, with the nanorings remaining in a saturated state after an in-plane magnetic field is removed. Applying a small negative field to the nanorings on MgO produces a magnetic structure similar to that seen in nanostructures with a 4-fold magnetocrystalline anisotropy.
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Katz, Rena J. (Rena Jenelle). "An injection-locked 674 nm laser for Strontium-88 ion trapping." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78509.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 45-47).
Energy levels of the valence electron of a single trapped ⁸⁸Sr+ ion can be harnessed as an effective qubit for quantum information processing. The qubit transition to a metastable energy state can be stimulated by a laser at a frequency of 444.779044 THz. A laser beam with higher intensity causes more rapid transitions between quantum states, and thus allows more computational operations within the coherence time of the system. The focus of this thesis is the design and construction of a more powerful laser to stimulate the qubit transition of the 88Sr+ ion, using injection-locking to stabilize the frequency of the new laser. Injection-locking is a technique for using an existing, stable laser to control the frequency of a second laser diode. A small amount of input power is enough to produce a much more powerful output beam at the same frequency, so the system acts as an amplifier. We found that a AlGaInP laser diode required 9 +/- 2 pW of injected input power to lock to the input frequency, producing an output power of 11.56 +/- 0.31 mW. The ratio of input to output power was (7.8 +/- 1.7) x10-⁴. The injection-locking frequency range was 18.4 +/- 1.6 MHz.
by Rena J. Katz.
S.B.
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Gielen, Fabrice Matthieu. "Single cell dielectrophoretic trapping for the analysis of cellular membrane dynamics." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9532.
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Cellular membrane dynamics has been subject to an ever-growing research interest since the introduction of the fluid mosaic model in the early seventies. The recognition that individual components of a cell membrane are able to diffuse in a two-dimensional matrix led to the crucial questioning of the structure-function relationship. The stunning diversity of lipid or proteins making up the plasma membrane of mammalian cells prevents theoretical treatment to apprehend membrane organization and dynamics. For this reason, membrane dynamics has remained up to now predominantly an experimental field of study. The presence of membrane micro-domains including lipid rafts and the co-existence of several phases has for instance been recently confirmed using single-molecule fluorescence detection methods. These domains as well as overall membrane fluidity are thought to be essential in many key cellular processes such as signal transduction, pathogen entry or trafficking. This thesis focuses on the development, characterization and applications of novel microfluidic tools for probing cellular plasma membrane structure and dynamics. We successfully demonstrated dielectrophoretic trapping of single mammalian cells (typically 10μm in diameter) as a means to facilitate time-resolved studies on living cell membranes for timescales of minutes. Firstly, microfluidic devices embedding micro-electrodes have been fabricated. These dielectrophoretic (DEP) traps were characterized to assess their potential as a tool for performing in-vitro membrane bio-assays. DEP traps have been subsequently used to trap single-cells near a defined surface and reagents were introduced via microfluidic channels. Incorporation of a Förster Resonance Energy transfer (FRET) acceptor dye within a donor labelled cellular membrane allowed for time-resolved observation of colocalization events using a scanning confocal microscope and fluorescence lifetime imaging. The presence of cholesterol was shown to influence probes localization. Such microfluidic devices coupled with high-resolution imaging of single cells can potentially be used to study the organization dynamics of individual molecules on the membrane of live cells.
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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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Gives, Pedro Mendoza de. "Interaction between nematodes and biocontrol agents with potential for use in biomanagement systems." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297988.
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Mirsadeghi, Seyed Hamed. "A silicon photonic circuit for optical trapping and characterization of single nanoparticles." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61374.
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In this thesis, two slightly different silicon-on-insulator (Silicon-on-Insulator (SOI)) planar photonic integrated circuits for optically trapping and characterizing single nanoparticles are designed, fabricated, and fully characterized. These symmetric (input/output) structures are formed by etching two dimensional patterns through a 220 nm thick silicon slab atop a micrometer thick layer of silicon dioxide, and are operated in a fluidic cell at wavelengths of ≈ 1.55 μm. Each consist of two grating couplers, two parabolic tapered waveguides, two single mode ridge waveguides, two photonic crystal waveguides and a single photonic crystal slot (PCS) microcavity, designed using a Finite Difference Time Domain (FDTD) electromagnetic simulation tool. The circuits are designed to concentrate continuous wave laser light incident on the input grating coupler to a small volume within the fluidic channel of the microcavity in order to achieve a high electric field intensity gradient capable of attracting and trapping nanoparticles from the solution via optical gradient forces.
The fabricated PCS cavities exhibit Q factors > 7500 and resonant transmissions as high as T = 6%, when operated in hexane and without undercutting the cavities. Due to fabrication imperfections, the cavity Q and peak transmission values were not as high as simulation predicted, nevertheless, these robust, devices were successfully used to optically trap single sub-50 nm Au nanospheres and nanorods with < 0.5 mW of laser power. Furthermore, it was found that while the particles were trapped, the transmitted laser intensity varied randomly in time, providing a simple means of characterizing the Brownian motion of the particle in the trap. The intensity variation is caused by the backaction of the dielectric object on the cavity resonance, the magnitude of which depends on the real part of the trapped particle’s polarizability tensor, and its position in the cavity. By exploiting this cavity-nanoparticle interaction, we developed a self-consistent analysis of the
transmission signal of circuits that enabled us to determine the size and anisotropy of the trapped nanoparticles without any direct imaging, with nanometer sensitivity.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Udén, Jonathan. "Development of Light Transmission Techniques for Quantification ofCO2 Trapping in Porous Media." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-263012.
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Light transmission can be used to measure the amounts of certain constituents within a system by analyzing the amount of light they have absorbed. The aim of this study was to improve methods for light transmission measurements in two phase systems. In this study, the main reason is to be able to use light transmission for measurements of CO2-trapping in natural sandstone. The latter is something that does not exist today. The study investigated the possibility to use selected liquids that both represent an analogue CO2-brine system and have similar refractive index as each other to simplify Beer-Lamberts law. The simplification suggested that a change in light intensity within a system was controlled solely by the length of a liquid that had replaced another liquid. Two methods were implemented to test this. A tank containing high transparency sand and glycerol was injected several times with dyed oil in order to test equations developed to calculate the length of oil that light had passed. The glycerol and oil were chosen due the ratio between them in density and viscosity. These are properties that make them ideal for modelling the trapping of supercritical CO2 in sandstone saturated with brine. The other method for testing was to measure a coefficient of light absorption for the oil, then applying that coefficient to an injection of a known volume of oil. The analysis results showed that a linear relationship exists between difference in light intensity and the volume of oil in a system. The developed equation for oil length, as a function of light absorption specific for that oil, is sufficient for calculating the volume of oil in the system. It could not be used for calculating exact values in each part of the tank. The placement of oil was crucial to the measured light intensity for a single point. Oil occuring further back in the tank gave lower values of light intensity than oil occuring in the front. The study show that with further investigation into the role of oil placement in the light path, a simpler method could be developed for some light transmission measurements. The method could be used in its current form for modelling CO2 in sandstone but should be further developed if exact values are importantLight transmission är en teknik som används för att mäta mängden av en vätska eller gas genom att låta ljus passera genom det och se hur mycket ljuset minskade i styrka. Tekniken används idag bl.a. för att titta hur föroreningar sprider sig i sand. Vid dessa mätningar så har man en tank med glasväggar fylld av sand och vätska. Syftet med denna studie är att ta fram en metod som gör light transmission mer tillgängligt och enklare att använda. Målet är att ta fram en metod som är så pass allmän att den går att applicera på naturlig sand och sandsten. I sandstenen testas CO2-trapping i djup berggrund. Modelleringen av CO2-trapping i sandsten är något som inte existerar idag med hjälp av light transmission teknik. Metoden i denna studie bygger på att förenkla den formel som normalt används för att beräkna ljusförluster när en stråle ljus passerar genom ett material, Beer-Lamberts lag. Förenklingen sker genom att noggrant välja konstituenterna som används så att den refraktion av ljus som normalt sker mellan två medium försvinner. De konstituenter som skall anpassa är vätskor som ska representera flytande CO2 samt saltvatten. Genom att ta en bild som sedan jämförs med bilder under tiden en injektion av olja sker, så skall enligt teorin endast längden olja som ljuset passera förändra ljusets styrka. De vätskor som väljs är en hydraulolja och glycerol. Dessa väljs eftersom att de beter sig liknande hur CO2 beter sig i saltvatten under högt tryck. 2D experiment på skalor av tiotals cm gör det möjligt att studera hur heterogenitet i sandstenen påverkar hur mycket CO2 som kan fastläggas och därmed lagras på ett säkert sätt. Mer avancerade visualiseringstekniker klarar ofta bara små prover med längdskalor på någon cm. Dessa använder t.ex. röntgenstrålning. I studien används flera kyvetter fyllda med olja som placeras efter varandra för att mäta hur ljusmängden förändras beroende på längden olja den passerar. Detta samband testas sedan på en tank fylld med sand, glycerol och en känd mängd olja. Oljans ljusabsorption framtagen med kyvetter visade sig att inte gå att använda på den uppställning den testades på. Ett annat försök att ta fram ljusabsorptionskoefficienten för oljan gjordes genom att injicera en känd mängd olja i flera steg i samma uppställning som tidigare testats på. Inte heller detta försök gick att använda eftersom koefficienten varierade kraftigt beroende på injektionstillfälle samt mängden olja den beräknades för. Det visade sig finnas en stark korrelation mellan mängden olja i tanken och skillnad i ljusmängd. Det gick dock inte att skapa något generellt samband mellan mängden olja i en specifik punkt och skillnaden i ljus. Det visade sig ha stor betydelse i vilken del av tanken som oljan befann sig. Den olja som låg längre bak i tanken gav mindre ljusskillnad än den som låg längst fram mot glaset. På grund av det starka sambandet mellan ljusskillnad och oljemängd så tyder det på att metoden borde gå att bygga vidare på, men vidare studier krävs. Den metod som testas här måste utvecklas ytterligare för att gå att applicera på sand eller sandsten.