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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.
41

Chemical scrubbing of odorous gas generated from hot-melted coal

Wang, Chia-ying 29 June 2010 (has links)
This study armed to develop a chemical scrubbing process to eliminate odorous VOCs (volatile organic compounds) in gases emitted from hot-melted coal tar used in bamboo antiseptic processing. Major VOCs are mono-aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAHs), phenol and ammonia. A pilot scrubber with a recycling scrubbing liquid tank and with an acrylic column of 0.10 m in length, 0.10 m in width, and 0.58 m in height, packed with 1¡¦¡¦ diameter plastic packings to a height of 0.38 m will be used for the scrubbing test of the emitted gas. Aqueous solutions of sodium hypochlorite (NaOCl), hydrogen peroxide (H2O2), detergent, and the Fenton¡¦s reagent (hydrogen peroxide with ferrous chloride) will be used as oxidants for the VOCs. Results indicated that with operation conditions of VOCs 20-30 ppm (as methane), an empty bed retention time (EBRT) of around 28.5 s in the packed section, and a sodium hypochlorite concentration of 450 mg Cl2/L with pH of 6, around 45.3-50.3% of the VOCs in the influent gas could be removed at a L/G (liquid to gas flow rate ratio) of 0.295 m3/m3. A test indicated that the overall odor(expressed as the dilution to threshold D/T value) removal was around 97.6% and the D/T were 1303 and 30.9, respectively, for the influent, and scrubber effluent. Using double packed towers to deal with coal tar odorous, result from the test indicated that 70-75 and 94.4% of VOCs and odorous intensity in the influent gas could be removed, respectively, with the operation of an initial sodium hypochlorite concentration of 450 mg Cl2/L with pH of 6, combined with a hydrogen peroxide concentration of 4000 mg/L with pH of 9 , VOCs (methane equivalent) concentrations of 20-30 ppm, gas flow rate of 8 NL/min, and a liquid/gas rate ratio of 0.295 m3/m3. At running 300 minutes can smell much odor than beginning. Baesd on the results from the pilot study, a full-scale plant with waste gas flow rate 200 m3/min was proposed. It was estimated that the cost is around NT$ 20.9 and 52.2 for treating 1,000 m3 of the emitted gases, respectively, for sodium hypochlorite, and sodium hypochlorite combined with hydrogen peroxide. Efforts should be made by decreasing the cost by other alternative technologies.
42

Microbial Reduction on Eggshell Surfaces by the use of Hydrogen Peroxide and Ultraviolet Light

Gottselig, Steven Michael 2011 August 1900 (has links)
Microbial Reduction on Eggshell Surfaces by the use of Hydrogen Peroxide and Ultraviolet Light. (August 2011) Steven Michael Gottselig, B.S., Texas A&M University Chair of Advisory Committee: Dr. Craig Coufal The effect of hydrogen peroxide (H2O2) in combination with ultraviolet light (UV) as an egg sanitization process on eggshell surfaces was studied. Preliminary experiments were conducted to develop an optimized methodology for eggshell disinfection that will be an effective and efficient way to reduce microorganisms on hatching eggs. Several experiments were conducted to reduce the natural flora found on the eggshell surface. Hatching eggs were collected from White Leghorn hens housed in floor pens with nest boxes. Eggs had no adhering organic material present. Results from these experiments led to the modification of the prototype equipment as well as the treatment application methodology. Following the experiments to optimize the methodology for H2O2 spraying and UV exposure time, the methodology was applied to eggs inoculated with Salmonella Typhimurium. Eggshell crush and rub methodology was used to enumerate bacteria within the pores and membranes of the egg. The optimized H2O2 and UV combination treatment process was then applied to commercial broiler breeder hatching eggs to evaluate the effects on hatchability. Based on the parameters tested, results indicate that two applications of 3% H2O2 followed by 5 sec of UV exposure after each application produced the most consistent microbial reductions on eggshells. To enhance these effects, the addition of a 180° rotation between the two applications showed to be effective at further reducing the natural flora found on the eggshell surface. Studies using this optimal methodology on eggs inoculated with Salmonella at 9 log10 CFU/egg yielded greater than 5 log10 CFU/egg reductions. However, this methodology had little to no effect on reducing bacteria found within the pores and membranes of the eggs inoculated with Salmonella. These findings indicate that the effects of the disinfection process are largely limited to the eggshell surface. Hatch studies showed significant reductions in eggshell microbial levels under field conditions with eggs having large amounts of organic material present on the shell surface. Hatchability was maintained after treatment when compared to untreated eggs. Additional studies are needed to develop advanced equipment to apply this technology under commercial conditions.
43

Quality and Sensory Attributes of Shell Eggs Sanitized with a Combination of Hydrogen Peroxide and Ultraviolet Light

Woodring, Kristy Senise 2011 August 1900 (has links)
Two experiments were conducted to evaluate the combination of hydrogen peroxide (H2O2) and ultraviolet light (UV) as an alternative eggshell sanitization procedure for shell egg processing. In each experiment, two cases of eggs (720 total) were collected at a commercial inline egg production facility. To assure egg uniformity, only eggs between 57 and 62 g were collected from a single hen house. Half of the eggs (360) were commercially processed (washer and sanitizing rinse) following normal procedures outlined by the U.S. Department of Agriculture (USDA) for shell egg processing (control group). The other half of the eggs (360) were washed as normal but without the sanitizing rinse. These eggs were then treated with 3 percent H2O2 and UV light (treated group). The treatment consisted of spraying the eggs with 3 percent H2O2 over the entire shell surface followed immediately by exposure to UV light for 5 s in an enclosed chamber equipped with germicidal lamps (UV-C). This treatment was performed twice. Eggshell aerobic plate counts (APC), eggshell breaking strength and thickness, albumen height and pH, Haugh units, and yolk color were measured after 1, 15, 30, 45, and 60 days of storage. On d 15 and 45, sensory evaluation of scrambled egg samples was conducted to determine if consumers could detect a difference between treatment groups using a triangle test. Results indicate APC for treated eggs were significantly lower than the control eggs for all sampling days in Experiment 1. However, due to low initial APC in the control eggs on d 1 of Experiment 2, no significant differences were observed for APC between control and treated eggs during storage. No consistent differences were found for eggshell and interior quality measures with the exception of albumen pH. Albumen pH was significantly higher in treated eggs than control on d 45 and 60 and d 1, 15, and 45 of Experiment 1 and 2, respectively, with only an average difference of 0.04 pH. In the sensory evaluation, only 33.5 percent of the participants correctly differentiated between the control and treated eggs. Data from this study suggests that H2O2 and UV light can be used as an alternative eggshell sanitizing procedure without impacting eggshell or internal egg quality.
44

Effect of Cadmium on Peroxidase Activity in Rice

Chen, Malcolm 28 May 2004 (has links)
Cd significantly inhibited the growth of both rice cultivars. The Tainung 67 cultivar is more tolerant to Cd than Taichung 1 cultivar after 48 h incubation in CdCl2 solution. The Cd tolerant cultivar¡XTainung 67¡¦s PODs in roots might synthesize more lignin in Cd-treatments. Meanwhile, the decrease of H2O2 levels is accompanied with the enhancement of POD activity in Cd-treated tissues. PODs here might also remove excess H2O2, thus serving detoxifying role and synthesizing more lignin for protection. In Taichung 1 cultivar, the accumulation of H2O2 in Cd-treated tissues could be due to the less amount of POD enhancement induced by Cd. In response to Cd treatment, the Taichung 1 cultivar also synthesizes little lignin, and therefore is Cd-sensitive.
45

The roles of superoxide anion and hydrogen peroxide in the rostral ventrolateral medulla on neural mechanisms of hypertension in spontaneously hypertensive rats

Lee, Chia-Yen 13 July 2005 (has links)
Maintenance of a stable arterial blood pressure is a complex physiological phenomenon. In addition to dysfunction of the blood vessels, alterations in homeostasis of circulating signals and humoral factors also contribute significantly to the development of hypertension. Recent evidence indicates that accumulation of the byproducts of cellular respiration, including superoxide anion (O2-) and/or hydrogen peroxide (H2O2), are contributing factors in pathophysiology of hypertension. With respect to the central nervous system, neurons in the rostral ventrolateral medulla (RVLM) play a pivotal role in neural regulation of blood pressure. RVLM neurons not only provide a tonic excitation to maintain the sympathetic vasomotor activity of the blood vessels, they also participate in baroreceptor reflex control of blood pressure. The notion that production of O2- and/or H2O2 in the RVLM participates in central control of blood pressure has recently gained major recognition in the area of hypertension study. Nonetheless, detailed insights into the mechanisms underlying O2- and/or H2O2 promoted hypertension remain to be elucidated. The hypothesis that forms the basis of this study is that enhanced level of O2- and/or H2O2 in the RVLM may be important factors for the manifestation of hypertension in the spontaneously hypertensive rats (SHR), an animal model of human essential hypertension. In comparison to normotensive Wistar-Kyoto (WKY) rats, basal level of O2- in the RVLM region of adult male SHR rats was significantly higher, along with a reduction in the expression of superoxide dismutase 1 (SOD1), SOD2 or catalase. SOD and catalase are enzymes that metabolize cellular O2- or H2O2 respectively. Pharmacologically, microinjection bilaterally into the RVLM of SOD mimetic, Tempol (50 nmol) or a pan SOD/calatase mimetic, FeTMPyP (100 nmol), significantly decreased mean systemic arterial pressure (MSAP) or heart rate (HR) in both SHR and WKY rats. The maximal hypotensive effect produced by Tempol or FeTMPyP was significantly greater in SHR than WKY rats. We also found that in SHR, but not WKY rats, the hypotensive and bradycardiac responses after microinjection bilaterally into the RVLM of FeTMPyP was significantly greater than that by Tempol. In addition, infection of RVLM neurons with adenoviral vector encoding SOD1 (Ad-SOD1), SOD2 (Ad-SOD2) or catalase (Ad-Catalase) gene (5x108 pfu) into the bilateral RVLM resulted in a long-term hypotensive effect in SHR but not WKY rats. The temporal profile of Ad-catalase-promoted hypotension was again longer than that promoted by Ad-SOD1 or Ad-SOD2 alone. At the molecular level, gene transfer of SOD1, SOD2 or catalase into the RVLM region of SHR or WKY rats specifically increased the expression of individual protein, resulting in a reduction in O2- level. Together these results suggest that accumulation of O2- and/or H2O2 in the RVLM is involved in the neural mechanism of hypertension in SHR.
46

Effect of Copper on Peroxidase Isozyme Genes in Arabidopsis thaliana Roots

Chang, Chia-jung 22 July 2005 (has links)
The adverse effect of Cu on growth is apparent from the reduction in root length of the Cu-treated Arabidopsis roots. Arabidopsis seems to be more resistant to Cu in comparison with that of soybean in terms of root growth. The increase of the levels of H2O2 was observed in Cu-treated Arabidopsis roots. The lignin biosynthesis related enzymes, PODs and laccases were enhanced during the Cu treatments. The lignin contents slightly increased in Cu-treated Arabidopsis roots. To our surprise, the Arabidopsis can be tolerant to high concentration of Cu (200 µM), because only part of high levels of H2O2 accumulated in Cu-treated tissues are used by PODs to synthesize the lignin.
47

Effect of copper on peroxidase gene in two rice cultivar

Lin, Hsin-hua 15 August 2005 (has links)
Copper-treated rice seeding (Oryza sativa cv. Tainung 67 and Taichung native 1) showed significant inhibition in rice root growth, and an enhancement in POD activity. POD within Tainung 67 rice roots might synthesize more lignin in Cu-treated tissue. Meanwhile, the decrease of H2O2 levels is accompanied with the enhancement of POD activity in Cu-treated tissues. The increase in POD activity induced by Cu might remove excess hydrogen peroxide serving a detoxifying role and synthesizing more lignin for protection. In Taichung native 1 rice cultivar, high amounts of H2O2 accumulated in Cu-treated tissues could be due to the less amounts of POD induced by Cu. In response to Cu treatment, the Taichung native 1 cultivar also synthesizes a little lignin, and is more Cu-sensitive. Therefore, The Tainung 67 cultivar is more tolerant to Cu than Taichung native 1.
48

Effect of Cadmium on Peroxidase Isozyme in two Rice Cultivars

Chen, Nan-ying 11 July 2006 (has links)
Cadmium-treated rice seeding (Oryza sativa L. cv. Taichung Native 1 and O. sativa L. cv. Tainung 67) showed inhibition in the growth of rice roots or leaves, and an enhancement in POX activity. In Tainung 67 cultivar, Cd treatment may have influence over cis-regulatory elements in POX promoter region and enhanced transcription of POX or enhance glycosylation of POX. The increase in POX activity induced by Cd might remove excess hydrogen peroxide serving a detoxifying role and synthesizing more lignin for protection. In Taichung Native 1 cultivar, high amounts of H2O2 accumulated in Cd-treated tissues could be due to the less amounts of POX induced by Cd. In response to Cd treatment, the Taichung Native 1 cultivar also synthesizes a little lignin, and is more Cd-sensitive. Therefore, the Tainung 67 cultivar is more tolerant to Cd than Taichung Native 1.
49

Effect of Cadmium on Peroxidase Isozyme in Arabidopsis thaliana Roots

Lin, Mao-yi 11 July 2006 (has links)
The adverse effect of Cd on growth is apparent from the reduction in root length of the Cd-treated Arabidopsis thaliana roots. The increase of the levels of H2O2 was observed in Cd-treated A. thaliana roots. The lignin biosynthesis related enzymes, POXs and laccases were enhanced during the Cd treatments. The lignin contents slightly increased in Cd-treated A. thaliana roots¡]48 h¡^. The A. thaliana can be tolerant to high concentration of Cd (500 µM), and only part of high levels of H2O2 accumulated in Cd-treated tissues are used by POXs to synthesize the lignin.
50

Effect of Zinc on Peroxidase Isozyme Genes in Arabidopsis thaliana Roots

Sheng, Lin-chin 18 July 2006 (has links)
The adverse effect of Zn on growth is apparent from the reduction in root length of the Zn-treated Arabidopsis roots. The levels of H2O2 were increased rapidly in Zn-treated Arabidopsis roots. The lignin biosynthesis realated enzymes, peroxidases and laccases were enhanced during the Zn treatments. The lignin contents increased in Zn-treated Arabidopsis roots. Arabidopsis can be tolerant to high concentration of Zn (4 mM), because part of high levels of H2O2 accumulated in Zn-treated tissues are utilized by peroxidases to synthesize the lignin.

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