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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis, Characterization, and Photophysical Properties of Scs Bis(N-Heterocyclic Thione) (Nht) Pd and Pt Complexes

Tyson, Virginia E 15 August 2014 (has links)
The use of OLEDs (organic light-emitting diodes) in display screens has become increasingly popular due to their improved energy efficiency, relatively low cost, and minimized generation of heat. For these devices, emitters with high photostabilities are desired and efforts in developing molecules of this caliber are increasing rapidly. In the work presented, treatment of an aryl-bridged, bis(N-heterocyclic thione) (NHT) pincer ligand precursor with [PdCl2(CH3CN)2] or PtCl2 yielded 6,6used ring, SCS-NHT Pd and Pt pincer complexes, which are stable in the presence of air. These complexes were found to have excellent photostabilities of 96 % and 93% retention of emission intensity, which make these complexes good candidates for uses in OLEDs. X-ray crystallography of the complexes, computational studies, and the catalytic activity of the SCS-NHT Pd complex are also reported. With advancements in photoluminescent compounds such as these, more energy-efficient display screens can be developed, reducing electricity costs world-wide.
2

The Study of Ra-228 in the Northern South China Sea and Luzon Strait

Lin, Hsiu-chuan 13 September 2005 (has links)
The South China Sea (SCS) is a large semi-enclosed marginal sea to the west of the tropical Pacific, and connected to the western Pacific through the Luzon Strait. The surface water circulation and hydrography in the SCS are strongly influenced by the East Asian monsoon system. The seasonal changes of the monsoon system induce changes in the mixed layer thickness, upwelling, primary production, and associated biogeochemistry. In order to understand the characteristics of the Kuroshio intrusion and the source strength of radium isotopes from the coastal zone, we carried out surface water and water column samplings for Ra-228 and Ra-226 measurements in the northern SCS and the Luzon Strait areas. The Ra isotopes were much higher in the SCS surface waters than in the open ocean surface waters because the SCS was enclosed mostly by landmasses which are known as sources of these nuclides. Higher surface water activities are seen in the northern (shelf and slope) area; lower values are observed in the southern (deep basin) area; the lowest values appear in the eastern (Luzon Strait) area. Large temporal and spatial variations were also observed probably due to the source strength of radium isotopes from the coastal zone and intrusion of the Kuroshio Current. The vertical 228Ra profiles are remarkably similar, showing high values in the surface layer and fairly uniform below about 500m depth but with an increase toward the bottom due to input from the underlying sediments. The shallow water profile on the shelf shows higher 228Ra values due to both vertical and horizontal mixing of the shelf water and additional source from the shore zone. The 226Ra profiles in the northern SCS are quite similar to those in the northwest Pacific both in pattern and magnitude, showing lowest values at the surface and an increase with depth although more scattered. 226Ra activities in the shallow water (less than 1000m depth) are higher in the northern SCS than in the northernwest Pacific Ocean, but they are quite comparable below this depth. The Ra-228/Ra-226 activity ratios of the surface water decrease from the coastal zone and estuaries toward the basin and the Luzon Strait (from 4.11 to 1.03), indicating the former as a main source area for Ra-228. The vertical 228Ra/226Ra activity ratios decrease rapidly from the surface at 2.3 to a depth of 1500m at 0.5 below which the values are less than 0.5. This pattern is similar to that of the open ocean but these values are much higher than those in the open oceans where the surface water values are 0.5 or less and the deep water values are less than 0.1. This suggests a strong input of Ra-228 relative to Ra-226 from the bottom sediments into the deep water of the semi-enclosed SCS.
3

Spatial and temporal distribution of thaliaceans (Tunicata) in relation to hydrography in the waters off southern Taiwan

Su, Yi-tien 09 June 2008 (has links)
This study investigated the spatial and temporal distribution in species composition and numerical abundance of thaliaceans (Tunicata) in relation to environmental factors in the waters off southern Taiwan between February 2004 and October 2005. In total, 18 thaliacean taxa belonging to 10 genera and 3 families were identified, with the mean abundance of 152 ¡Ó 33 ind./100m3. The abundance of thaliaceans showed clear seasonal change, higher in winter. The five most dominant species were Thalia rhomboides, Pyrosomella verticillata, Doliolum denticulatum, Thalia orientalis and Thalia democratica. They were widespread oceanic species, and together constituted 82 % of the total thaliaceans. The abundance of thaliaceans showed significant negative correlation with temperature. Different predominant thaliacean species showed different correlationship with environmental factors; Thalia rhomboides, Doliolum denticulatum and Thalia orientalis were significant and negatively correlated with temperature. Result of ANOVA test revealed that the abundance of thaliaceans and hydrography had significant seasonal differences in the waters off southern Taiwan, but showed no significant difference among stations. The variation of dominant thaliacean species composition among the water masses was small, implied that the influence of water masses on the distribution of thaliaceans was minor.
4

Strategic Concessions: Negotiating Human Land Use to Serve the Habitat Needs of the Eastern Meadowlark

Hagstrom, Richard Evan 24 January 2018 (has links)
Our civilization is facing increased populations and scarcity of habitat for a variety of species. Encroaching on these landscapes while engaging in habitat fragmentation and destruction, has negatively impacted biodiversity and subsequently put thousands of species at risk of going extinct. With humans causing peril for various species via habitat losses and degradation due to our developing of landscapes, as Landscape Architects, we have a responsibility to minimize, negate, or rectify these losses and while still providing serviceable landscapes for our fellow humans. One possible avenue to pursue when motives for the well being of the collective are being considered is designing landscapes that serve both human and species in unison, with services being provided for humans and satisfying the needs of wildlife. This project is based on a desire to accommodate the needs of a growing community by providing a stormwater retainment system serving as a pedestrian artery to a historic river, while also accommodating the needs of wildlife by establishing a constructed meadow that satisfies habitat requirements for the Eastern Meadowlark. Through analysis of storm water volumes, building code setbacks regarding waterways, habitat requirements of the Eastern Meadowlark and land volume manipulation, a solution to many obstacles facing community and species has been posited in this project: the Dianna Dayle River Walk. / Master of Landscape Architecture
5

Spinal cord stimulation with implanted epidural paddle lead relieves chronic axial low back pain

David A. Stidd, Rivero, Sergio, Weinand, Martin 08 1900 (has links)
UA Open Access Publishing Fund / Introduction: Spinal cord stimulation (SCS) provides significant relief for lumbosacral radiculopathy refractory to both medical and surgical treatment, but historically only offers limited relief for axial low back pain (LBP). We aim to evaluate the response of chronic axial LBP treated with SCS using a surgically implanted epidural paddle lead. Materials and methods: This is a retrospective review of a consecutive series of patients with exclusive LBP or predominant LBP associated with lower extremity (LE) pain evaluated and treated with SCS using an implanted paddle lead within the dorsal thoracic epidural space. Baseline LBP, and if present LE pain, were recorded using the visual analogue scale (VAS) at an initial evaluation. At a follow-up visit (a minimum of 12 months later), LBP and LE pain after a spinal cord stimulator implantation were again recorded using the VAS. Patients were also asked to estimate total LBP pain relief achieved. Results: Patients with either exclusive (n=7) or predominant (n=2) axial LBP were treated with SCS by implantation of a paddle lead at an average spine level of T9. The baseline VAS score for LBP was 7.2; after a follow-up of 20 months, the score decreased to 2.3 (P=0.003). The LE pain VAS score decreased from 7.5 to 0.0 (P=0.103). Patients also reported a subjective 66.4% decrease of their LBP at follow-up. There were no surgical complications. Conclusions: Axial LBP is refractory to many treatments, including SCS. SCS using a surgically implanted paddle electrode provides significant pain relief for chronic axial LPB, and is a safe treatment modality
6

Seasonal and spatial dynamics of abundance and growth rates of picophytoplankton in the South China Sea and the Kuroshio

Liu, Yi-Xain 07 July 2012 (has links)
This research studied the seasonal and spatial dynamics for abundance of picophytoplanktons (including Prochlorococcus spp., Synechococcus spp. and picoeukaryotes) in the South China Sea (SCS) and the Kuroshio. Waters were collected during five cruises between August 2009 and December 2010. Growth rates were determined in two size fractioned waters, <2 um and <10 um, after incubation. The differences of growth rates between the two size fractions were defined as the grazing rates. Before the incubation, waters were enriched with FeCl3, EDTA, or NH4Cl to examine the possible shortage of Fe or nitrogen. Abundances of picophytoplanktons and nanoflagellates were examined using a flow-cytometry and a microscope, respectively. Prochlorococcus was more abundant in the warm than the cold seasons and in the Kuroshio and the basin of the SCS than in the shelf and slope of the SCS. In the high abundance seasons/regions, low irradiance enhanced the growth rates of Prochlorococcus. Although both of the growth rates and grazing rates were high during then, the growth rates were found higher than the grazing rates. Addition of EDTA enhanced the growth rates that was likely attributed to its chelating with toxic trace metals (such as Cd2+, Cd2+) and/or with growth necessity trace metals (such as Co2+). The seasonal/spatial distributions for Synechococcus were in contrast to that of Prochlorococcus. High growth rates of Synechococcus were related to high nitrate concentrations and the low irradiance. The growth rates were higher than the grazing rates in the high nitrogen seasons/regions when/where irradiance was also relatively low. EDTA also enhanced the growth of Synechococcus, and was likely due to its chelating to remove Cd2+ and/or to retain Co2+. Distributions of picoeukaryotes were similar to that of Synechococcus. Factors affected its dynamics were not clear because of its complicated compositions.
7

Supply of available iron in the Kuroshio and South China Sea as studied by the expressions of iron deficiency induced protein A in Trichodesmium spp.

Huang, Bo-Ruei 19 February 2011 (has links)
This research studied the iron deficient condition of the nitrogen-fixing filamentous cyanobacteria Trichodesmium in neighboring oligotrophic northern South China Sea and upstream Kuroshio. The iron deficiency was detected by the immunocytochemical analysis of the expression of iron deficiency induced protein A (IdiA), a protein translated by Trichodesmium cells under iron deficiency. IdiA expression rate (percentage of cells stained by IdiA antiserum in total cells) was used to represent the iron deficiency status. Trichodesmium samples were collected in four cruises by net-towing or bottle-sampling in the Kuroshio and the shelf, slope and basin of the South China Sea between December 2008 and May 2010, representing three seasons: Spring (CR899 and CR1455), Summer (CR910) and Winter (CR886). The results showed that the IdiA expression rates vaied greatly among the stations in the South China Sea. Iron supplies from various sources decreased the IdiA expressions rates (i.e., less iron deficient). These sources include: (1) Mixing from deep layer, such as in the continental shelf of the South China Sea in which internal wave occured, and upwelling occurred in the continental slope; (2) Mixing at some stations in the South China Sea basin from the input of river dischange, especially in the events after typhoon. During these events, stations with lower surface water salinities usually implied lower IdiA expression rates. In contrast, the basin station that were high in salinities showed high IdiA expression rates, higher than the rates in the Kuroshio. These stations generally had strongly stratified water coulumn, and therefore might limit the ward mixing of deep water. The incubation experiment conducted showed that 24 hours after adding iron, Trichodesmium IdiA expression rates were significantly decreased. The Kuroshio, with its water column stratification weaker than South China Sea, the IdiA expression rates were lower than the basin stations in South China Sea, and positively relatied with the stratification index, indicating that deep advection may be the main source of iron. In the incubation experiments in Kuroshio, the expression rates did not significantly differ with iron or without iron addition. The IdiA expression rates in both regions were not related to flux of atmospheric dust, indicating the input from the dust was not key point to decrease iron deficiency of Tricodesmium in this two region. This study shows that iron deficient condition of diazotrophic Trichodesmium in South China Sea and upstream Kuroshio were related to vertical mixing and horizontal discharge, but not dust flux. This study is first time to apply immunocytochemical analysis on field experiments to explain iron deficiency in the ocean.
8

Temporal variability of dissolved inorganic carbon at SEATS site:estimation of net community production (2002-2004)

Shih, Yung-Yen 27 June 2005 (has links)
Dissolved inorganic carbon (DIC), titration alkalinity (TA), and nitrate + nitrite (N+N) are measured from seasonal cruises at the time-series site SEATS in the northern South China Sea (18¢XN 116¢XE) between March 2002 and November 2004. The most distinctive feature of the annual nDIC (DIC normalized to a constant salinity of 33.8) cycle is an increase in wintertime and a decrease in summertime (March¡VAugust). The nDIC drawdown (-3.15 ¡Ó 2.23 mmol m-2 day-1) at summertime is mainly attributed to biological uptake of DIC. The other terms in the DIC budget calculation, i.e. the carbon fluxes of air-sea CO2 gas exchange, horizontal advection and vertical diffusion, are estimated to be -0.48 ¡Ó 0.31, -0.70 ¡Ó 0.86, and 2.50 ¡Ó 0.59 mmol m-2 day-1, respectively. Accordingly, results from the DIC budget calculation reveals a net community production (NCP) of -4.47 ¡Ó 1.98 mmol m-2 day-1. This calculated NCP from our data is in good agreement with the export and new production previously reported in the South China Sea. The consistency demonstrates that carbon system is almost in a steady state during summertime at SEATS. According to the Refield C : N ratio of 106 : 16, a flux of 0.67 ¡Ó 0.30 mmol m-2 day-1 of bioavailable nitrogen (Nbio) is needed to sustain the calculated NCP. The source terms in the Nbio budget calculation, i.e. the nitrogen fluxes of vertical diffusion, wet deposition, dry deposition and the contribution from the putative nitrogen-fixing cyanobacteria Trichodesmium and Richelia intra., are estimated to be 0.20 ¡Ó 0.04, 0.03 ¡Ó 0.01, 0.04 ~ 0.08, and 0.02 ~ 0.13 mmol m-2 day-1, respectively. It thus seems that all the source terms can only collectively account for 50 ~ 70% Nbio needed to support the estimated NCP. With this regard, unicellular cyanobacteria, which have been reported as an important N2-fixer in the subtropical North Pacific and identified by the nitrogenase genes (nifH) in the small size (less than 10
9

Radioactive Disequilibrium Between 210Pb and 210Po in Water Columns of the Luzon Strait and the Northern South China Sea

Su, Yu-tien 13 September 2005 (has links)
The purposes of this study are to understand and compare: the distributions of the particulate and dissolved 210Po and 210Pb in the northern South China Sea and in the east and west sides of the Luzon Strait; the associated biogeochemical processes, including their mechanisms and rates involved in the area; and the disequilibrium between 226Ra and the 210Pb as observed in profiles. Seawater samples were collected from three stations in the northern South China Sea (station I, J, and F) and one station to the east of the Luzon Strait (station S5) using a Rosette sampling system during three Ocean Researcher I cruises (ORI-688 in July, 2003, ORI-707 in February, 2004, and ORI-734 in October, 2004). The dissolved 210Pb in surface water generally displays higher activities (around 14-28 dpm/100kg) relative to deep water, reflecting atmospheric input. The dissolved 210Pb profile as seen at station F displays a maximum of 26 dpm/100kg at 200 m and lower values at about 10 dpm/100kg below 1500 m. Highest value at 28 dpm/100kg was observed at S5 surface water. It is probably due to being on the path of the Kuroshio which has accumulated atmospheric 210Pb continually from the northern Equatorial Current on its way. The mean residence time with respect to particle scavenging is about 0.62 years for total 210Po within a 50 m mixed layer, and ranges between 0.34 to 1.13 years for total 210Pb in the mixed layer. 210Po is deficient relative to 210Pb in most profiles, suggesting that 210Po is more readily scavenged. The mean scavenging residence time is about 87 years for total 210Pb in the deep water at station F, and 60 years at station J. This residence time is longer than that in both the Pacific and East China Sea deep waters, i.e. a lower scavenging rate in the South China Sea. As the upwelling rate is much higher in the South China Sea than in the Pacific, it may effectively reduce the sinking rate of the sinking particulates, resulting in higher 210Pb residence time in the water columns of the South China Sea.
10

STORM WATER BUILD-OUT ANALYSIS: AMBERLEY VILLAGE

HOFFA, SAMANTHA 01 July 2004 (has links)
No description available.

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