Browsing by Subject "Ethylene"
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Item Abiotic Stress Effects on Physiological, Agronomic and Molecular Parameters of 1-MCP Treated Cotton Plants(2012-02-14) Da Costa, Vladimir AzevedoAbiotic stresses impact cotton (Gossypium hirsutum L.) affecting physiological, molecular, morphological, and agronomic parameters. One of the main yield components in cotton production is the number of bolls per unit area. However, boll abortion is increased when cotton experiences various stresses during its reproductive development that can consequently reduce lint yield. Prior to abscission, a burst in ethylene is observed which may be assumed to be the signal necessary to initiate abscission of that particular structure. It is desirable to prevent fruit loss that may be induced by the peak in ethylene prior to abscission. One potential option to cope with the loss of cotton reproductive structures is the use of ethylene inhibitors. The overall objective of this research was to establish if 1-MCP would synergize, ameliorate, or overcome the effects of abiotic stresses on physiological, molecular, morphological, and agronomic parameters of cotton plants under abiotic stress conditions in field and greenhouse studies. Field and greenhouse experiments were conducted from 2007 to 2009 as a randomized complete block design with four replications in the field, and as a 2x2 factorial design in a split-block arrangement with five replications in the greenhouse. Field treatments consisted of three rates of 1-MCP (0, 25 and 50 g a.i. ha-1) in combination with a surfactant applied at mid-bloom. One day later, ethephon (synthetic ethylene) was applied as a source of abiotic stress. Greenhouse treatments were two 1-MCP rates (0 and 2.4 g a.i. L-1) during a14-h overnight incubation that were then subjected to two water regimes (control and stressed) as the source of stress. Greenhouse assessments with gas exchange analysis revealed that water deficit stress started to impact plants at a moderate water stress, 5 days after 1-MCP treatment (DAT) and a water potential (?w) of -1.4 MPa. The 1-MCP increased water use efficiency in well-watered plants at 1 DAT. Many of the yield components, plant mapping, and biomass parameters investigated were detrimentally affected by drought. However, drought increased specific leaf weight, chlorophyll content, and harvest index. The 1- MCP improved reproductive node numbers mainly during drought, but did not lead to a better harvest index, since 1-MCP caused high abscission. Ethylene synthesis and molecular investigations in greenhouse conditions showed that at 1, 5, 7, 9, 11, and 13 DAT, ethylene production of stressed plants never exceeded those of control plants. As the ?w became more negative ethylene production rate was reduced among stressed plants independent of 1-MCP treatments. However, at 1 DAT 1-MCP caused a transient climacteric stage (ethylene synthesis increase) in leaves. The two primary genes associated with ethylene synthesis, ACS6 (1-aminocyclopropane-1-carboxylic acid synthase) and ACO2 (1-aminocyclopropane-1-carboxylic acid oxidase) expression generally showed an identical trend that supported the ethylene synthesis data. The 1-MCP did not ameliorate any of the detrimental effects of water stress on gas exchange at the point where it started to impact cotton plants. 1-MCP had little or no positive effect on plant mapping, dry matter partitioning and chlorophyll content. Field investigations revealed that at harvest, fruit set in the upper portion of the canopy was influenced by 1- MCP. This portion of the canopy had a greater number of full size, yet immature bolls, which potentially could have had a positive influence on the lint yield. However, ethephon caused the highest lint yield since ethephon treated plants had more open bolls and total bolls in the lower canopy at harvest.Item Economical analysis of a new gas to ethylene technology(Texas A&M University, 2007-09-17) Abedi, Ali AbdulhamidEthylene is one of the most important petrochemical intermediates and feedstocks for many different products. The motivating force of this work is to compare a new process of ethylene production developed at Texas A&M University to the most common processes. Ethylene is produced commercially using a wide variety of feedstocks ranging from ethane to heavy fuel oils. Of them, the thermal cracking of ethane and propane using a fired tubular heater is the most common process in the United States. In Europe and Japan, where natural gas is not abundant, thermal cracking of naphtha using a fired heater is the most common process. In addition to these processes; ethylene could also be produced from crude oil by autothermic and fluidized bed techniques and from coal and heavy oils by synthesis from carbon monoxide and hydrogen. At Texas A&M University, a group of researchers developed a new process that can convert natural gas into liquids (GTL) or to ethylene (GTE). This technology is a direct conversion method that does not require producing syngas. When selecting a process for ethylene production, the dominant factor is the selection of hydrocarbon feedstocks. Based upon plant capacity of 321 million pounds of ethylene per year, this study has shown that using natural gas, as a feedstock, is more economical than using ethane, propane, naphtha, and other feedstocks. Therefore, it is more economical to convert natural gas directly to ethylene than separating ethane or propane from natural gas and then converting it to ethylene. A process simulation package ProMax is used to run the GTE process; and a software program, Capcost, is used to evaluate fixed capital costs of the GTE process. Finally, the cost index is used to update the cost of the other processes of ethylene production today.Item Simulation and optimization of an ethylene plant(Texas Tech University, 2000-05) Yan, MeisongThe objective of this project is to develop a simplified ethylene plant model, which includes a thermal cracking section, a separation system and an integrated refrigeration system, and use it to study plant-wide time-domain optimization. The mixture of ethane and propane is feedstock for the cracking furnace while free radical mechanism is a basis for the decomposition of hydrocarbons, A one dimensional plug flow model, integrated by LSODE package, is employed to describe the species profile, temperature profile, pressure profile, and coke thickness profile, and benchmarked by the industrial data. The pyrolysis gas is sent to a series of distillation for separations into the final products. An approximate model with lumping technology is used to predict the top and bottom product impurity and the required refrigerant, which are also benchmarked by plant data. NPSOL is used to search the optimal operation points for the processes. Because of the simplification in the modeling work, preliminary optimization results are obtained. The optimization results show that the furnace part is the heart of the ethylene plant while the separation system and refrigeration system limits the maximum furnace effluent. By adjusting the feedstock flow rate and the dilution steam to hydrocarbon ratio, the gross profit of the plant is increased by 6%, comparing to the base case data.Item The catalytic oxidation of ethylene to ethylene oxide(Texas Tech University, 1936-05) Roberts, Stiles MoxleyNot available