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Apart from being a support, the three substrates had their own roles in the growth of CNTs. Bamboo charcoal also acted as a catalyst provider. Au-coated silicon wafer participated in the formation of the silica/CNT composite nanowires. Copper foil itself was a catalyst. The silicate, the Au/Si droplet, and the copper particles were the catalysts for the growth of CNTs in these three substrates, respectively. The formation of the CNTs followed the vapor-liquid-solid (VLS) route which involved the decomposition of ethanol vapor into carbon, carbon dissolution inside the liquid catalyst and precipitation to form CNTs. / CNTs could be grown in a very wide temperature range (700-1400°C), but specific substrate for a particular temperature range was needed. The structures of the CNTs varied with the CVD processing conditions. The forms and the amount of catalytic material entering the interior of the CNTs depended on the characteristics of the catalyst for that process / The products formed on different substrates had their own characteristic features . Hollow or silicate filled CNTs with silicate droplet tips were formed on the surface of bamboo charcoal. Their diameter was in hundreds of nanometers and the length was about several microns. CNT-coated silica core-shell structures were obtained on Au-coated silicon wafer. The graphitic carbon shell was formed in thickness about 145 nm for the sample prepared at 1185°C, but amorphous carbon shell was produced in thickness more than 300 nm for the sample prepared at 1236°e. Lastly, CNTs with bamboo-like structure were synthesized on the copper foil substrate. The CNTs were getting thicker from 70 nm to 170 nm when temperature was increased from 700°C to 1000°C. The yield increased with temperature and annealing time if the sample was annealed for less than 30 min. / We report the growth of carbon nanotubes (CNTs) on different types of substrates with or without catalytic materials by using different approaches. The roles of the substrates and the catalysts in the formation of the CNTs are studied . We also characterized and identified the structural properties of the CNTs products. In this work, three types of substrates had been used, namely biomorphic bamboo charcoal , Au-coated silicon wafer, and copper foil. The CNTs were grown on different substrates by chemical vapor deposition (CVD) method at temperature range between 700°C and 1400°C. Ethanol vapor was used as the carbon source, while tetraethyl orthosilicate (TEOS) vapor was also applied to the process for bamboo charcoal. / Zhu, Jiangtao = 碳納米管在不同類型基底上的生長 / 朱江濤. / Adviser: D. H. L. Ng. / Source: Dissertation Abstracts International, Volume: 72-11, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Zhu, Jiangtao = Tan na mi guan zai bu tong lei xing ji di shang de sheng chang / Zhu Jiangtao.

The charcoal market in Africa is an informal economy. This enables millions of people to earn a living producing, selling and trading charcoal, due to low barriers to market entry. However, research and policy on charcoal has long focused on the downsides of informality. Informal charcoal production is commonly linked to criminality, an undermining of social cohesion, poor working conditions and most of all, forest loss. These negative perspectives continue to shape our approaches to charcoal markets, despite a recent reframing of charcoal as a potential sustainable development opportunity. This thesis aims to provide an alternative perspective. I argue that by focusing on the negative aspects of charcoal production, in particular forest loss, we end up misdiagnosing the problems and excluding stakeholders. The focus on forest loss has obscured research on the role of charcoal in rural livelihoods and has led to research that is primarily interested in large-scale production providing charcoal to major urban areas. This means small-scale charcoal production has been comparatively neglected in academic research, despite its importance for rural livelihoods and overall charcoal supply. Through three empirical chapters, I provide perspectives on small-scale charcoal production, its role in rural livelihoods and some of the factors that shape this role. I strive to provide novel analytical insights by moving away from questions of charcoal’s environmental impact and towards an approach that situates charcoal within the politics of rural livelihoods. I explore these ideas using case studies from Mozambique and a mixed methods approach. The results show small-scale charcoal production is a flexible form of income, primarily used as a livelihood diversification strategy. Furthermore, charcoal production is closely linked to the agricultural practices of producers. This means that conventional theoretical approaches to forest loss that treat charcoal production as distinct from agricultural practice may misinterpret the role of charcoal production in deforestation and forest degradation. I then move on to look at approaches to charcoal market formalisation in Mozambique. The results show that the regulations, whilst shaped by a variety of processes, concentrate on governing charcoal as an environmental problem. Changes to forest management requirements within the regulations have done little to improve sustainability as they are incapable of reaching out to small producers, in part due to inherent barriers within the formalisation process - stringent forest management plans and a conceptualisation of charcoal as a full-time, professional livelihood. The picture of charcoal production that emerges from the thesis is one of a flexible cash-income generating strategy, complicated by the politics of forest loss and livelihoods at local and national levels. The results show that charcoal plays a vital role in rural economies, not only in spite of its informality, but because of it. I argue throughout the thesis that small-scale charcoal production should be seen as a livelihood strategy to be nurtured rather than neglected and marginalised. The research questions whether the formalisation and modernisation of charcoal markets can engage small producers and concludes that in order to allow charcoal livelihoods to flourish and to improve sustainability, interventions need to work with, and for, charcoal as an informal economy.

Stratigraphic analyses of lacustrine sediments provide powerful tools for reconstructing past environments. The records that result from these analyses are key to understanding present-day climate mechanisms and how the natural environment may respond to anthropogenic climate change in the future. This doctoral dissertation research investigates climate and environmental history at Laguna Saladilla (19° [degrees] 39' N, 71° [degrees] 42' W; ca. 2 masl), a large (220 ha) lake along the north coast of Hispaniola. I reconstructed changes in vegetation and environmental conditions over the mid to late Holocene based on pollen, microscopic charcoal, and diatoms in an 8.51 m sediment core recovered from the lake in 2001. Fieldwork in December 2009 included the use of ground penetrating radar to identify subaqueous deltas that indicate past positions of the Masacre river, which flows into the lake from the Cordillera Central. Laguna Saladilla was deeper and more saline from the base of the sediment profile approximately 8030 cal yr BP to about 3500 cal yr BP. Mangrove (Rhizophora) pollen percentages were highest around 7650 cal yr BP, when mollusk shells in the core suggest marine conditions. The lake became progressively brackish ca. 3500 cal yr BP, followed by a transition ca. 2500 cal yr BP to its current freshwater state. This shift in water chemistry was likely due in part to a change in the position of the Masacre river. Diatoms show that lake levels decreased as evaporation/precipitation ratios increased. Amaranthaceae and other herbs dominated the pollen record under the drier conditions of the last 2500 cal yr BP; pollen of fire-adapted taxa, particularly Pinus, increased in the last 800 years. Patterns of microscopic charcoal influx at Laguna Saladilla over the Holocene are similar to patterns at Lake Miragoane, Haiti and Laguna Tortuguero, Puerto Rico. The changes in fire frequency or extent indicated by these Caribbean charcoal records may be driven by increased winter insolation at ca. 5000 cal yr BP that led to earlier winter drying. Comparing the charcoal record to archeological data and other paleoenvironmental records facilitated the disentangling of changes in climate from anthropogenic impacts.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 62-77). Also available on the World Wide Web.

Sclerotium bataticola Taub., the sclerotial stage of Macrophomina phaseoli (Maubl.) Ashby, was first described as the cause of a sweet potato rot in 1913... Since then, it has received considerable attention as the cause of crown blights or charcoal rot of at least 284 species of plants. [...]

The ecotone between aspen parkland and mixed-grass prairie in mid-eastern Alberta is a climatically-sensitive area that has been subject to periods of enhanced aridity occurring at multi-decadal to centennial-scale cycles throughout much of the last 6000 years. To assess the ecotonal response to changes in effective moisture, as inferred by diatom-inferred salinity, temporal variations in pollen and charcoal preserved in a sediment core from Chauvin Lake were analyzed over several diatom-inferred moisture-cycles from c. 5,400 to 3,300 YBP. Changes in landscape vegetation were inferred by variation in both the percent relative abundance and influx rates of pollen taxa found in a sediment core from Chauvin Lake. Variation in sediment charcoal accumulation rates for both total charcoal and morphotypes, as well as the percent relative abundance of charcoal morphotypes, were used to infer changes in landscape fire regimes during these aridity cycles. One-way ANOVAs were used to determine significant differences in average accumulation rates or relative abundances between the arid and more mesic periods. Changes in the relative abundance of Cyperaceae and Ambrosia pollen between wet and dry periods suggests a shift in the spatial arrangement of vegetation, and a decrease in the sediment influx of most taxa, suggests a decrease in production of landscape vegetation during periods of aridity. Charcoal morphotype analysis, especially variation in Type M, Type D and Type B, suggests fewer, more intense fires during periods of drought. Lack of change in total charcoal may be related to increased secondary sedimentation of charcoal during periods of drought due to increased soil erosion. This study suggests that the spatial arrangement and production of landscape vegetation is dependent on climate, and fire prevalence decreases during periods of drought due to reduced fuel availability. / Thesis (Master, Biology) -- Queen's University, 2009-01-29 12:15:32.137

Wildfire is an ecological disturbance that plays an important role in ecosystem function and interacts with climate and vegetation, relationships that may be altered by ongoing climate change. Insights from paleoecology can provide context for environmental change, including the natural range of variability. Here, the Holocene fire history of a small watershed in eastern Ontario, Canada is reconstructed. A high-resolution macroscopic charcoal series was derived from the lacustrine sediment of Mud Lake, north of Gananoque, Ontario and within the Frontenac Arch. Analysis of the charcoal record estimates a mean fire-return-interval (FRI) of 175 yr/fire around Mud Lake during the Holocene, and similar mean FRIs during different time periods indicates that it has been a largely stationary fire regime. The analysis suggests that fire activity may have recently increased, but a lack of documentary fire records for the area leaves this uncertain. There is no indication that humans have significantly impacted the fire regime, though anthropogenic ignition could have played a role in the area’s recent fires. The fire regime around Mud Lake does not appear to have shifted in association with major changes in regional vegetation. Fire activity does correlate with some paleoclimate trends. The estimated fire frequency decreased around 7500 yr BP, when wetter summers became more common in eastern Canada, and a recent increase in fire frequency would parallel with more frequent incursions of dry and cool air masses into the region. During other parts of the record, however, the fire activity does not appear to reflect the major climate impacts. The fire history of Mud Lake is relevant to the ecological management of eastern Ontario’s St. Lawrence Islands National Park and its restoration of a rare, fire-dependent tree species, the pitch pine. Though predictions vary, this area’s climate may become more favorable to fire through an increase in temperature and a decrease in summer precipitation. By providing information about the natural variability of fire activity in eastern Ontario, this research can be applied towards setting appropriate management goals during future environmental change. / Thesis (Master, Environmental Studies) -- Queen's University, 2010-02-01 00:14:00.711

The boreal forest region of Canada is climatically sensitive and may be impacted by anthropogenic-induced climatic changes. The results of this multi-proxy paleolimnological study contribute detailed information on changes to the boreal forest in northwestern (NW) Ontario, showing unequivocal changes in lake and forest structure due to climate during the warmer mid-Holocene. This study uses diatoms, pollen, and charcoal reconstructions to better understand the timing and extent of climate-related changes in Lake 239, Experimental Lakes Area (ELA), in NW Ontario throughout the Holocene with an emphasis on the warmer mid-Holocene. Diatom analysis revealed changes in water quality based on analysis of species assemblages and quantitative inferences of total phosphorus from a deep central core. Lake levels at least 8-m lower than today were inferred from a near-shore core and were concurrent with an increase in nutrient-rich diatom assemblages, an increase in diatom accumulation, and a decrease in chrysophytes relative to diatoms in the central core. A concurrent increase in pollen such as Cupressaceae and Ambrosia indicate more open boreal forest between ~4500-8000 cal yr BP. Pollen-based inferences of temperature suggest an increase on average of 1-2°C warmer than today with winter temperatures up to 4°C warmer. The pollen inferences also suggest enhanced precipitation, but with increased evaporation/evapotranspiration resulting in reduced moisture availability overall. A transect of cores surrounding ELA was synthesized using pollen-based reconstructions of temperature and precipitation to assess regional changes. All sites show shifts in pollen assemblages indicating a warmer mid-Holocene; prairie sites to the west show mid-Holocene decreases in precipitation relative to today, whereas sites near or east of ELA show consistent increases in precipitation, but with enhanced evaporation. Charcoal analysis shows an increase in charcoal accumulation during the mid-Holocene warm period compared to the early and late Holocene, suggesting a more active fire regime. Fire return intervals based on type-M charcoal show a pronounced decrease during the early-to-mid Holocene period and a corresponding increase in fire frequency, whereas fire frequency derived from total charcoal was virtually unchanged over the Holocene. This study helps fill a knowledge gap in NW Ontario noted by several large regional assessments. / Thesis (Ph.D, Biology) -- Queen's University, 2010-07-15 09:54:18.653

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