Browsing by Subject "LED"
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Item Coordinated response and regulation of carotenogenesis in Thermosynechococcus elongatus (BP-1) : implications for commercial application(2014-12) Knight, Rebecca Anne; Brand, Jerry J. (Jerry Jay), 1941-; Alper, Hal S.If small isoprenoids, the starting component of carotenoids, can be efficiently excreted from thermophilic cyanobacteria, they could help satisfy the demand for sustainably produced hydrocarbons. This is the driving force behind wanting to understand the response and regulation of isoprenoid pathways to environmental stimuli in the thermophilic cyanobacterium, Thermosynechococcus elongatus, BP-1. The portion of the isoprenoid pathway studied here is the carotenoid pathway since these products are critical to adaptation and they encompass the largest pool of isoprenoid compounds in cyanobacteria. Although synthetic biology in cyanboacteria has improved in recent years, there are many undiscovered metabolic complexities that make large-scale commercial production challenging. To address this need, I quantify and report for the first time metabolic shifts within the carotenoid pathway of BP-1 due to combined effects of temperature, pH and blue light. I show that metabolism shifts from the dicyclic into the monocyclic carotenoid pathway in response to pH, and that decreasing temperature drives flux into the end products of both pathways. Also, I report that the productivity of an uncommon carotenoid, 2-hydroxymyxol 2’-fucoside (HMF), approached 500 μg/L-day in cultures grown at 45 °C, high light intensity, and pH 8. In order to further elucidate these responses, I analyzed 42 RNAseq samples taken over time of BP-1 induced by cold and heat stress and compared these results to metabolomics data. I showed that crtR and crtG, two central carotenogenesis genes, are transcriptionally controlled and used weighted gene co-expression network analysis (WGCNA) to determine eight separate co-expressed modules of biological significance. Among the co-regulated heat response and cold response genes there were three and five non-coding RNA, respectively, providing targets for future investigation. Using subtractive genomics and transcriptional data I narrowed the potential missing steps of the myxol pathway in cyanobacteria to seven unknown BP-1 genes, two of which were confirmed not to be involved in the missing step(s). Finally, by generating a ΔcrtG mutant and testing it under different environmental parameters, I showed that HMF does not protect against high pH or low temperature (despite up-regulation at these conditions), and that CrtG has a higher affinity for monocyclic than dicyclic carotenoids.Item High-K Based Non-Volatile Memory Devices with the Light Emitting Application(2014-09-05) Lin, Chi-ChouThe zirconium-doped hafnium oxide (ZrHfO) high-k gate dielectric films with and without the embedded nanocrystals have been studied for the applications of the nonvolatile memory and light emitting devices. By replacing the polycrystalline Si with the novel discrete nanocrystal embedded high-k ZrHfO structure, the promising memory functions can be expected. On the other hand, by using the same metal oxide semiconductor (MOS) capacitor structure with ZrHfO gate dielectric layer but different operating gate voltage (Vg) ranges, e.g., when Vg is larger than the breakdown voltage (VBD), the device starts emitting the white light. This new solid state incandescent light emitting device (SSI-LED) unveils a new concept for the future LED evolution. The nanocrystals cadmium selenide (nc-CdSe) and molybdenum oxide (nc-MoO3) embedded ZrHfO on the p-type silicon wafer have been fabricated by self-assembly process and studied for their charge trapping, detrapping, and retention characteristics. Moreover, the temperature effect on the memory function has been investigated on the nc-MoO3 embedded device. More than half of the originally trapped holes can be retained in the CdSe nanocrystals for more than 10 years. For the temperature test, with the increase of temperature, the memory window was enlarged and the Coulomb blockade effect was suppressed in the nc-MoO3 embedded ZrHfO memory device. At the same time, the interface quality was deteriorated, the leakage current was increased, and the lifetime was shortened. The light emission characteristics of the new SSI-LED composed of the ZrHfO or WO3 thin film have been investigated. The light emitting principle is based on the thermal excitation of the conductive paths formed after the dielectric breakdown, which is different from the electron-hole or exciton radiative recombination mechanism in conventional LEDs. The emission spectrum covers the visible to the near IR wavelength range with the color rendering index of 98.4. The light intensity can be enhanced by embedding CdSe nanocrystals into the ZrHfO dielectric layer due to the increase of the defect density which causes the enhancement of the leakage current. The SSI-LED has a very long lifetime of > 5,664 hours in the atmosphere. Lastly, the additive gas effect of a plasma-based process for etching the copper film over a near-vertical step has been investigated. A new process that minimizes the excessive attacks of the cusp region was developed.Item Re/connect : an interdisciplinary exploration of wearable technology in devised theatre(2015-05) Weller, Kristen Ann; Glavan, James; Beckham, Andrea; Lowery, AllisonHow can theatrical costumes help develop a narrative about intimacy in a world that is increasingly detaching from physical contact? My thesis explores this question through interactive costumes and the use of Wearable technology. I created two micro-controlled costumes that employed a variety of proximity sensors and LEDs that light in reaction to the touch and closeness of another person. The costumes are a response to the statement made by MIT psychologist Sherry Turkle: "We're lonely, but afraid of intimacy." The garments were featured in both an interdisciplinary devised theatrical production I helped create, entitled RE/CONNECT, and an interactive educational exhibit, illustrating the importance of physical touch in an increasingly digital age. Only by integrating new and old technologies will theatre remain relevant and funded in a world that is losing interest in physical interaction. Beyond the benefits of study for the production team, the final thesis performance attracted audience members from a wide demographic range, including those outside of the theatrical community with positive results. By incorporating nontraditional technologies in performance, and allowing audience members to experience these technologies firsthand outside of a museum, I have challenged my colleagues in the theatre and sciences to further investigate applications of developing technologies, and put to art and technology in deeper conversation.Item The Investigation of the Effects of Low Light Laser Therapy on Insulin Secretion in Porcine Islets, a Pilot StudyRaptis, Darren James; Huang, Floyd; Mason, Carolyn; Moore, KellyLED light technology is used in this pilot study to demonstrate the ability to create a cost effective light apparatus using 1-watt LEDs with wavelengths of 740nm,850nm, and 940nm to test for an increased insulin response using porcine islet of Langerhans cells. This is building on recent research showing increased insulin response in rat islet cells when exposed to LED light. However, due to the high variance and low sample size, statistically significant changes were not measured when irradiating cells with 740nm, 850nm, and 940nm LED light using 7.9 J/cm2 and 15.8 J/cm2 dosages along with low and high glucose conditions. There are however possible trends of increased insulin secretion that may become significant with increased sample size. There is a need to repeat this study to definitively determine if increased insulin secretion does occur in porcine islet of Langerhans cells along with any potential negative effects and what the optimal wavelengths and dosages would be. Using the cost effective light apparatus, additional wavelengths can be experimented with to cover between 300nm to over 1600nms. The information garnered from this research has the potential to improve islet of Langerhans cell transplantation for type one diabetes (T1D) patients by decreasing the number of cells needed to be therapeutic and increasing insulin release.