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CW 266nm all solid state ultraviolet laser resonant cavity Feedback controlTsai, Cheng-Yu 27 June 2000 (has links)
In this work, we use Coherent produced 532nm cw laser as pump source, and 266nm is obtained by frequency doubling. The ring cavity of a laser is generally subject to various perturbation, and the stability of a single-mode laser can be improved by electronically locking its frequency. We use a Pound-Drever-Hall laser frequency stabilization system to control the cavity length. This method utilizes an external phase modulator to produce the sideband and is capable of detecting weak signal to get the information of cavity disturbation. Finally, the signal is dealt with electrical circuit and then feedback to a PZT to control the stabilization of the cavity length.
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Cellular Effects of HDGF(hepatoma-derived growth factor) Expression in 3T3 cellsMa, Yi-Ling 28 June 2002 (has links)
Hepatocellular carcinoma (HCC) is the most common and devastating malignant tumor in Taiwan. The major factors involved in the molecular pathogenesis for the development of HCC have been explored in recent years. An extensive array of growth factors and their receptors have been identified and may act as positive and negative modulators in different stages of hepatocarcinogenesis. HDGF (hepatoma-derived growth factor) is a novel growth factor, identified from conditioned medium of hepatoma cell line. HDGF has growth stimulating activity for fibroblast and some hepatoma cells. The high homology of protein sequence to HMG (high mobility group) protein but with distinct structure indicate it is a novel growth factor with mitogenic effect. Recently, elevated HDGF expression was found in developing kidneys but little in adult kidney. Besides, HDGF expression was found to be correlated with angiogenic status of tissues. Thus, it is speculated that HDGF plays a role during embryonic development and angiogenesis. Besides, HDGF also plays a role in cell-to-cell interaction and cell movement. HDGF is a growth factor that is involved in stimulating vascular smooth muscle cells (SMCs) proliferation during development and in disease. HDGF contains a true bipartite nuclear localization sequence necessary for nuclear targeting. It is required for HDGF stimulation of DNA replication and cell proliferation in vascular smooth muscle cell. In present studies, have transfected HDGF cDNA to 3T3 cell and the HDGF expression was verified by Western blot analysis. HDGF expression altered the morphologies and growth rate of 3T3 cells by 2-fold. Besides, HDGF-expressing cells were more resistant to serum-starvation. Injection of 3T3-HDGF cells, but not 3T3 cells, resulted in tumor formation in nude mice, suggesting that the angiogenic and mitogenic functions of HDGF might contribute to carcinogenesis. By using various reagents including H2O2, dexamethasome, taxol, cisplatin, CoCl2 and KCN, the cellular stress studies revealed differential responses between in 3T3 and 3T3-HDGFH. analyzed dose and time-dependent effects of UV irradiation and found that 3T3-HDGF cells are more sensitive to UV irradiation than 3T3 cells and susceptible to apoptosis. hope these experiments will bring further insights into the cellular function of HDGF, particularly during angiogenic process, thereby enable to evaluate its role during HCC progression and its potential as clinical marker and therapeutic target for HCC.
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Fabrication and Measurement of Gapless Micro Lens ArrayChang, Chin-nan 11 September 2007 (has links)
Computer-aided design and simulation software are used in this thesis. AutoCAD is used to create pattern and mask; Pro/E is applied to build 3D model. TracePro software is used to simulate the optical performance. We use software for simulation and analysis. The data from simulation and analysis will be helpful to increase the strike-rate in process. Photolithography process is applied in this thesis for gapless crack polygonal lens array fabrication. In this process, photo resistance, AZ-4620 is spun on the substrate, and expose it after mask alignment, followed by the developing process. The cylinder column with the same size in diameter is formed after this process. Next, apply heat to photo resist. The cylinder structure becomes semi-sphere due to surface tension effect. Then, sputter silver layer on the semi-sphere. The semi-sphere becomes metal mold after nickel electroforming. Nickel alloy core is formed after electroplaing. Then, apply UV cuve resin on the nickel alloy core, and spinning out the extra UV glue. Then, cure it with UV light. Gapless crack polygonal lens array is completed after this series process. The result shows that it can be applied on different optical devices.
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The Study of ZnO/Si Layered SAW Oscillator for UV DetectionCheng, Po-Shu 15 August 2008 (has links)
The highly c-axis oriented ZnO films were deposited on silicon substrates by reactive RF magnetron sputtering in this study. The optimal two-step deposition parameters for ZnO films, which are oxygen concentrations of 70 % (1st step) and 50 % (2nd step), RF power of 100 W and sputtering pressure of 25 mTorr, are obtained by means of XRD, SEM and AFM analysis. Al films are deposited under optimal deposition parameters, which are DC power of 100 W and sputtering pressure of 4 mTorr, to form IDT electrodes with low sheet resistances. Therefore, Al/ZnO/Si layered SAW devices were fabricated under these optimized manufacturing parameters.
An oscillator based on a Al/ZnO/Si layered SAW device was fabricated for the application of UV detection and then investigating the acoustoelectric effect between surface acoustic wave and ultraviolet light illumination. Due to the fact that the sensor sensitivity is directly proportional to the resonance frequency, in this study the SAW device with high resonance frequency of Sezawa mode is adopted to form SAW oscillator for high sensitivity. The resonance frequency of SAW oscillator is 751.41 MHz. The optimal detecting zone for UV light is the center of IDT electrode with maximum sensitivity of 8.12 ppm/(£gW/cm2).
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Exploring the jumping spider mimicry of Eugauria albidentata (Lepidoptera, Crambidae, Musotiminae) through ethological and visual ecological approachesWang, Mu-Yun 12 August 2009 (has links)
Predator mimicry refers to a peculiar and rarely investigated example of Batesian mimicry in nature. This mimicry scenario exists between predator and prey in which prey resembles the form, behaviour or signals exhibited by the predator to avoid or reduce risk of predation. In the Lepidoptera, there are many micromoth taxa that are phylogenetically unrelated and geographically widespread exhibiting colour patterns that are putatively involved in jumping spider mimicry. In the present study, we aimed to answer the following questions: (1) what kinds of colour pattern and display behaviour could really allow the moths to participate in jumping spider mimicry? (2) does the moth receive different predation pressure from male and female spiders? (3) why is the mimetic moth not immediately taken by the spider? Is it really because the spider sees the moth as another spider? (4) Is there any evidence justifying any visual signal displayed by the moth participated in the jumping spider mimicry? The experimental results showed that the predation rates on mimetic moths of jumping spider were significantly lower than the non-mimetic moths, and spiders exhibited specific behaviour that was displayed for conspecific communication. But not all the presuming mimicking moths can decrease predation from the spiders. Female spiders show significantly higher predation rate to the mimicking moths, while male spiders tend to display more frequently to the moth. In behaviour comparison test in male jumping spiders, we found the behaviour displayed toward mimicking moths are closer to conspecific or heterospecific female spiders, suggesting that female spiders are more likely to be the model of the mimicry systems. Previous studies have shown that UV and fluorescent signals are important in courting behaviour of jumping spider, so we block the UV reflectance signals on the wing pattern of the mimetic moths. The results show that the predation rate of moths without the UV signals is significantly higher than control group which blocked the non-ultraviolet patterns. However, there were still several jumping spiders displayed to the UV-blocking moth, suggesting the UV signals are not the only feature participate in the jumping spider mimicry system.
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Resursoptimering av spelgrafikHagström, Karin January 2010 (has links)
<p>Detta arbete handlar om hur man som grafiker kan optimera utnyttjandet av tillgängliga resurser och trots begränsningar i form av polygon- och texturbudgetar öka sina möjligheter att skapa estetiskt tilltalande grafik. Arbetet undersöker en rad olika tekniker som kan användas för att resursoptimera material samt testar och utvärderar dessa med hjälp av material från spelprojektet Break a Leg (BAL). Resultaten visar att det grafiska materialet i BAL tjänat otroligt mycket på att resursoptimeras och att optimeringen förbättrat den tekniska kvaliteten avsevärt genom ökat texelvärde och effektiviserad vertexdensitet och gett en positiv visuell inverkan. Genom att integrera resursoptimering i det naturliga arbetsflödet ökar man som grafiker sina möjligheter att skapa estetiskt tilltalande grafik utan att överskrida de förutbestämda tekniska gränserna.</p>
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Compact diode-pumped solid-state lasersSpiekermann, Stefan January 2004 (has links)
<p>Compact diode-pumped solid-state lasers (DPSSL) arecontinuously replacing traditional gas lasers as well asenabling completely new technology. However, compact and costefficient designs are required to satisfy end-user demands. Theaim of this thesis was therefore to investigate novel laserdesigns for given applications considering these demands. In alarge part of the thesis work, nonlinear optics were employedto realize laser wavelengths where there was no appropriatelaser transition available.</p><p>Besides other nonlinear crystals such as BBO, LBO and KTP,periodically poled KTP played an important role in this thesiswork. Its unique properties regarding up conversion processeswere exploited, thus supplying a broadened view over itspotential and limitations.</p><p>This thesis places emphasis on practical concerns, mainlyrelated to real applications. It gives solutions to the beamshaping of laser diodes, covers the simulation and the designof laser dynamics as well as laser performance and describesthe sources of laser output degradation and damage mechanisms.Novel infrared lasers were designed and multiple intra-cavity,external cavity and non-resonant multi-pass frequencyconversion schemes were successfully employed and optimized.These produced red, orange, green, blue and ultraviolet outputfor various applications like spectroscopy, micro machining andwriting of fiber Bragg gratings.</p><p><b>Keywords:</b>diode-pumped solid-state lasers, nonlinearoptics, frequency conversion,</p>
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The effect of treatment on the quality of harvested rainwaterKeithley, Sarah Elizabeth 25 June 2012 (has links)
Harvested rainwater is an alternative water resource that can be utilized to help meet the world's growing demand for fresh water. Although harvested rainwater is often considered to have adequate physical and chemical qualities, its microbial quality has been found lacking. This study sought to better understand the effect of common treatment processes on the quality of harvested rainwater for potable use by examining two treatment processes: (1) batch chlorination followed by filtration, and (2) filtration followed by ultraviolet (UV) irradiation. The batch chlorination studies used rainwater harvested from four pilot-scale roofs in Austin, Texas with different roofing materials: concrete tile, green, Galvalume[Trademark] metal, and asphalt-fiberglass shingle. Chlorine tends to react with natural organic matter and produce disinfection byproducts (e.g., trihalomethanes (THMs)) that are harmful to human health. Chlorinating rainwater harvested from the metal and concrete roofs achieved adequate disinfection (total coliforms less than 1 colony forming unit per 100 mL) without forming THMs that exceed the United States Environmental Protection Agency (USEPA) limit of 80 [mu]g/L for public water systems. Chlorinating rainwater harvested from the shingle roof achieved adequate disinfection but had the potential to form excessive THMs. Chlorinating rainwater harvested from the green roof, which had the highest concentration of dissolved organic carbon, did not achieve adequate disinfection and formed THMs that were four times higher than the USEPA limit. Filtering the chlorinated rainwater from every roofing material with a block activated carbon filter generally resulted in increased bacteria concentrations and decreased THM concentrations. To study the effect of UV irradiation, cistern-stored and treated rainwater were sampled from a full-scale residential system in Austin, Texas, where the owner uses rainwater as his primary potable water supply. UV irradiation at the full-scale system effectively disinfected rainwater when the turbidity and total coliform concentrations were low, but disinfection was compromised as these two parameters increased as the drought progressed in 2011 and the ambient temperature increased. This research suggests that under certain conditions, treatment by either chlorination or UV irradiation can improve the quality of harvested rainwater so that it conforms to drinking water standards for public water systems. / text
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Environmental degradation of poly(ethyleneterephthalate)Mohammadian, Mehrdad January 1993 (has links)
The degradation of amorphous and orientated PET is investigated by several analytical methods. In this study, samples of both amorphous and orientated PET material were exposed to wet and dry soil, various humidities and temperature as well as UV irradiation. Results of accelerated ageing studies indicate that the amorphous sheet and biaxially orientated bottles degrade mainly due to de-esterification and oxidative chain scission due to their low crystallinity. At high temperatures (70-90) breakdown, as characterisedb y viscosity and chain scission measurements,is indicative of significant polymer deterioration. Breakdown is enhanced by increasing temperature, increasing relative humidity and UV irradiation. In this regard the polyester bottles are more stable than sheet due to a greater degree of orientation and hence higher degree of crystallinity. However, the rate of degradation is also a function of the surrounding environment. During the course of degradation, an increase in crystallinity was observed for both sheet and bottles. The rate of increase in crystallinity is initially rapid and is associated with plasticization by moisture and subsequent annealing. The dry conditions and UV irradiation cause negligible increase in crystallinity . An increase in the number of end groups was observed which is due to chain scission. Whilst the carboxyl and hydroxyl end groups were increased at the same rate asthermally degraded samples, the increase of carboxyl end groups for UV degraded samples was significantly higher than hydroxyl end groups. This increase is initially sharp and then more gradual with almost the same rate as hydroxyl end groups. A higher level of carboxyl end groups is due to the release of carbon dioxide and carbon monoxide mainly on the surface of the polymer. In this work two methods were used to introduce stability to the polymer. The first was preconditioning the polymer in an inert atmosphere for 48 hours at 600C which had a better effect for bottles This stabilizing effect was observed for both thermal degradation and UV irradiation of polyester materials. The second method was stabilizing polyester against UV irradiation by the incorporation of naphthalenea nd benzophenoned erivatives to the structure of the polyester. In this case the dihydroxybenzophenone showed the greatest stabilizing effect. Hydroperoxide formation during hydrolytic degradation is found to be both temperature and humidity dependent and appears to play a secondary role in thermal oxidation.
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Understanding the Effect of Wastewater Flocs Properties on UV Disinfection KineticsArmioun, Shaghayegh 20 November 2013 (has links)
Wastewater microbial flocs can protect microorganisms from inactivation by UV light. This effect is detected as tailing at high UV doses in the UV dose response curve. A double-layer structure composed of an inner compact core surrounded by a loose outer layer was proposed by earlier studies to describe UV resistance of microbial flocs. Due to limited oxygen diffusion into the compact cores, the UV inactivation of compact cores and microbial flocs under anaerobic conditions needed to be addressed. The UV disinfection kinetics under anaerobic culturing condition was nearly identical to that of the aerobic study. Moreover, the role of iron concentration on the differences in the UV inactivation kinetics of flocs and cores was assessed. The increase in UV absorbance of floc material due to iron addition could dominate the UV disinfection kinetics of flocs and cores such that they exhibited similar UV disinfection kinetics.
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