• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 53
  • 32
  • 7
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 125
  • 125
  • 40
  • 35
  • 14
  • 9
  • 9
  • 9
  • 9
  • 8
  • 8
  • 7
  • 7
  • 7
  • 6
  • 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.
11

Seasonal Variation in the Ability of Milk and Whey to Support Lactic Culture Growth

Norton, Rick Cameron 01 May 1982 (has links)
Milk samples from two cheese plants with overlapping milk supplies were collected monthly for one year in an attempt to measure seasonal variation in the ability of milk and whey to support lactic culture growth . Treatments to control and minimize variability of milk or whey were evaluated to optimize stability in starter culture performance. Raw milk samples were tested for somatic cell counts, activity tests (modified Horrall- Elliker), acid degree values, and total plate counts. Activity (modified Horraii-EIIiker) and inhibitory tests were also performed on pasteurized, pasteurized-vacuumized and high heat milk treatments. Rennet whey (heated and unheated) was collected from raw and pasteurized-vacuumized milk and tested for lactic culture performance by monitoring growth under pH control for 16 h and measuring milli-equivalents of neutralizer (NaOH) added. Lactic culture performance and stability in raw milk was poor in all seasons. Culture performance in high heat milk was poor, but demonstrated good repeatability. Pasteurized milk supported good lactic culture performance and stability. Pasteurized-vacuumized milk provided excellent lactic culture performance and stability throughout the year. Culture performance during December through March demonstrated the greatest variation. The cultures performed more uniformly during April through August. September was a transition month. Cultures demonstrated uniformity and optimum culture activity during October and November.
12

Host-specificity and seasonal variation of dicyemid mesozoan infection in octopuses of the tropical waters

Hsu, Chia-Ling 02 September 2003 (has links)
Dicyemid mesozoans are endoparasites inhabited in benthic cephalopod molluscs. Previous studies of dicyemids were mostly concentrated on their taxonomy. The life cycle remains a mystery since Cavolini observed this animal in 1787. The purpose of this study is to investigate further on the dicyemid life cycle building on the limited knowledge from previous studies, and investigate the infection of dicyemid in octopuses in tropical waters, using the area in the southwestern Taiwan as a model. A total of 324 octopus hosts was collected¡Aincluding 3 genera and 13 species from DungGang Fish Market from 2001 to 2002. There were 9 host species detected with dicyemid mesozoans including 14 species within 2 genera. Moreover, there is no dicyemid species overlap among the octopus species indicating high host-specificity. There is large range of the dicyemid infection prevalence among octopod hosts. Cistopis indicus has the highest prevalence (91%) and Octopus luteus the lowest (20%) in this study. In C. indicus, the infected mechanism correlated with season. The infusoriform larvae of dicyemid mesozoan dispersal from the host to sea water in the autumn and winter, then entering host in the spring and summer. The change of dicyemid life cycle stage in the C. indicus kidney correlates with the sharp decrease of infection intensity. However, the dicyemid infection in Octopus marginatus correlates with body size, not with season. Besides, there is significant difference of dicyemid development between two kidneys of the same individual, both in the analysis of C. indicus and O. marginatus. It indicates the separated way of dicyemid infection into two sides of kidneys.
13

The Analysis of the Causes and the Variations on Ozone and Related Air Pollutants in Taitung Area

Kuo, Chien-cheng 06 September 2006 (has links)
ABSTRACT Taitung area was commonly seen as a particularly clean environment. But the air quality has diminished lately similar to that seen in some parts of the populated western area in Taiwan, with ozone (O3) concentration levels rising every year. Because ozone is a byproduct of photochemistry, its accumulation is not only related to the discharge of local pollutants such as nitrogen oxide compounds (NOx), volatile organic compounds (VOC) and the introduction of external pollutants, but also related to the meteorological conditions. This research began with comparing the long-term trends of ozone concentration level and related pollutants in the Taitung area with those found in other survey stations spread in Taiwan. Through factor analysis, the relationship between air pollutants and meteorological parameters are analyzed. Finally, a screening of the events of abnormal ozone concentrations, followed with detailed analysis of the hourly data during these events and the discussion of the possible reasons for the comparatively poor air quality during these events and their correlations with seasons and meteorological conditions. Analysis of the trends in monthly averaged concentration of ozone shows that the annual rate of change (AR) is increasing at all stations under this study, except the Guanyin station being -0.18%. Taitung station has relatively higher levels every spring (March - May) and fall (October ¡V November); the annual rate of change is higher than other east area in Taiwan and the Hengchun station. These seasonal variation (SV) shows a progressively increasing north to south trend, Hengchun station being the highest and Taitung station being the second highest, indicates that concentrations of ozone are influenced by seasonal changes. By using the method of factor analysis to analyze the relation among ozone concentrations, meteorological parameters and pollution parameters, resulted in a direct relationship to the wind speeds over the four seasons. The results show a negative relationship to the atmospheric pressure during summer. The ozone concentrations of the Taitung station show a direct relationship to the Hualian station, which indicates the north to south dispersion relationship. The Analysis of the abnormal event also shows that typhoons may be an important carrier for transporting external pollutants into the area.
14

Investigation of temporal and spatial characteristics of carbonyl compounds in the Atmosphere in Kaohsiung

Wu, Chun-I 29 June 2007 (has links)
The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. Source apportionment analysis using factor analysis shows that the principle sources at Nanzi were traffic exhausts (motor, diesel, and gasoline vehicle) and stationary sources (industry, restaurant and chemical processes). The main sources at Siaogang were traffic exhausts (motor and gasoline vehicle), stationary sources (industry and restaurant) and secondary photo-chemical reactions.
15

Seasonal Variation of Chemical Hydrography in the Southern Penghu Channel

Lin, Hsin-chi 26 June 2003 (has links)
Abstract The Penghu Channel (PHC), situated in the southeastern Taiwan Strait (TS), is the major conduit for the South China Sea water (SCSW) and Kuroshio subsurface water flowing into the TS. However, the previous studies in this area were largely focused on the aspects of physical oceanography, with scant attention to the chemical hydrography is poorly studied, and therefore little understood. In order to better understand the seasonal variations of chemical hydrography in the southern PHC, we conducted a systematic survey of chemical hydrography aboard R/V Ocean Research III during cruises in January, March, July and October 2001 as well as March 2002. The water above 200m in the southern PHC is characteristic of salinity and temperature between those of SCSW and Kuroshio water (KW), suggesting it is mixing between these two waters. Nonetheless, the salinity and temperature below 200m are dominated by the SCSW. The relative amount of SCSW and KW flowing into the PHC has varied seasonally and annually. During the transition period of monsoon, KW was more than SCSW, but SCSW had a larger quantity during the northeast and southwest monsoon. The slope of the regression line between the d13CDIC and PO4-3 (0-100m, -0.55; below 100m, -0.30) indicates that the distributions of d13CDIC and PO4-3 in the study area may be controlled by the effect of air-sea exchange or the mixing of different water masses or both. In addition, to evaluate the overall error in d13CDIC analysis, we have checked carefully whether the different storage bottles, the various duration of storage, and different amount of saturated HgCl2 solution added in the water samples would produce uncertainty on the d13CDIC analysis. Our results show no significant discrepancy among these the different treatments, suggesting that the water samples can be stored without measurable d13CDIC change at least for 3 months.
16

Temporal and spatial characteristics of atmospheric carbonyl compounds in Kaohsiung Area

Huang, Chin-hung 04 July 2008 (has links)
The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nan-Chie ¡BHsiung-Kong¡BRen-Wu and Lin-Yuan sites. Factor analysis was also used to determine the source apportionment in the Kaoshiung area. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83, 28.91, 11.46 and 10.06 £gg/m3) at four sites, followed by formaldehyde (5.03, 6.92, 7.88 and 6.59 £gg/m3), respectively. The highest concentration of total carbonyls at Nan-Chie and Hsiung-Kong was 65.42 £gg/m3 and 85.09 £gg/m3 in summer, the lowest concentration was 25.06 £gg/m3 and 37.12 £gg/m3 in winter, relatively, the highest concentration of total carbonyls at Ren-Wu and Lin-Yuan was 49.94 £gg/m3 and 55.24 £gg/m3 in winter, the lowest concentration was 24.48 £gg/m3 and 11.78 £gg/m3 in autumn. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls. The results of factor analysis showed that the principle sources at Nan-Chie were traffic exhausts (diesel and gasoline vehicle) and stationary sources (metal assembly, waste treatment, pulp and restaurant). The principle sources at Hsiung-Kong were traffic exhausts (diesel, and gasoline vehicle), stationary sources (leather, chemical process and restaurant). The main sources at Ren-Wu were traffic exhausts (gasoline vehicle) and stationary sources (metal assembly, chemical process and restaurant). The main sources at Lin-Yuan were traffic exhausts (diesel vehicle) and stationary sources (metal assembly, leather, steel production and restaurant).
17

Sensory profiles and seasonal variation of black walnut cultivars and the relationship between sensory characteristics and consumer acceptance of black walnut gelato

Lynch, Catherine A. (Catherine Anne) January 1900 (has links)
Master of Science / Food Science Institute / Kadri Koppel / Black walnut (Juglans nigra L.) is a Juglans species native to the United States. Nuts are collected each fall from black walnut trees and the kernels are consumed in many food products like ice cream, candies, and baked goods. Flavor profiles of black walnut cultivars have been examined, but no studies have looked at the effect of growing season on flavor profile, and few studies have determined consumer acceptance of black walnut food products. The sensory profiles of 10 black walnut cultivars (Football, Vandersloot, Brown Nugget, Pounds, Sparks 127, Davidson, Sparrow, Neel, Emma K, and Tomboy) were evaluated using descriptive sensory analysis. A trained panel scored the intensity of 3 appearance, 7 aroma, 23 flavor, and 6 texture attributes. Results showed that the cultivars differed significantly (P≤0.05) on 11 of these attributes. The results from this study were also compared to results collected in 2011 of 7 black walnut cultivars. Two flavor attributes (black walnut ID and overall nutty) had an interaction effect of year and cultivar, while 7 attributes showed a main effect of year (brown, caramelized, floral/fruity, fruity,-dark piney, musty/dusty, and oily). In general, flavor attributes had higher intensities in 2011 than in 2013. Six of the black walnut cultivars were also incorporated into a gelato base and evaluated by both a trained panel and consumer panel. Trained panelists developed a lexicon for the gelato samples and scored the intensity of 18 flavor attributes. The gelato samples differed on 3 main flavor attributes: black walnut ID, overall nutty, and sour (P≤0.05). Based on consumer liking, there were 3 distinct clusters of consumers. One cluster preferred samples with a milder black walnut flavor, another preferred a more intense black walnut and overall nutty flavor, and the third cluster liked all of the samples. Results from this study indicate that growing season should be considered when determining flavor profile of agricultural products. These results can also help guide growers in selecting cultivars that may produce a more consistent crop year after year, and cultivars that consumers find acceptable in food products.
18

Efeito alelopático das folhas de Schinus terebinthifolius Raddi em espécies nativas da restinga de Massambaba / Allelopathic effect of Schinus terebinthifolius leaves on Massambaba restinga native species

Ana Beatriz Romana Viveiros 30 April 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Schinus terebinthifolius Raddi (Anacardiaceae) é uma espécie nativa da América do Sul com grande distribuição geográfica e muito comum em áreas de restinga. Sua grande plasticidade ecológica e boa interação biótica a torna espécie-chave na restauração de ambientes, porém, sua dominância pode estar relacionada à liberação de compostos alelopáticos. O objetivo do estudo foi avaliar o potencial alelopático dos extratos aquosos e óleos essenciais de folhas de Schinus terebinthifolius nas diferentes estações do ano sobre espécies-alvo nativas da restinga (Cereus fernambucensis, Erythroxylum ovalofolium, Pilosocereus arrabidae), uma espécie agrícola (Lactuca sativa) e nela própria (autoalelopatia). Para isso, suas folhas foram coletadas sazonalmente na restinga de Massambaba para o preparo dos extratos aquosos e extração dos óleos essenciais. Os extratos aquosos foram obtidos através da secagem das folhas a 60 C, trituração em liquidificador, diluição em água destilada e filtração, obtendo as concentrações de 5, 10, 15 e 20%. As extrações dos óleos foram realizadas através da hidrodestilação de 300 g de folhas frescas. A análise da composição dos óleos essenciais foi realizada através de cromatografia gasosa utilizando fibra SPME. O efeito fitotóxico foi avaliado nas espécies-alvo através da porcentagem de germinação, velocidade de germinação, crescimento aéreo e radicular, condutividade elétrica e massa seca. O efeito alelopático dos extratos aquosos foi observado em todas as espécies-alvo, principalmente sobre as espécies nativas. Esse efeito variou nas estações do ano de forma dose-dependente e espécie-específica. Os óleos essenciais de S. terebinthifolius também foram capazes de inibir a germinação e crescimento das espécies-alvo, e, da mesma forma que os extratos aquosos, esses efeitos variaram nas estações do ano e para cada espécie. Sugere-se que essas diferenças estejam relacionadas às fenofases de S. terebinthifolius e condições ambientais da restinga. Esse efeito fitotóxico, se comprovado em campo, pode restringir a utilização de S. terebinthifolius na restauração de ambientes. / Schinus terebinthifolius Raddi (Anacardiaceae) is a South America species with large geographical distribution, being common in Coastal Sandy Banks areas. Its ecological plasticity and good biotic interactions makes it a key specie in habitat restoring, but its dominance may be related to the release of allelopathic compounds. The objective of the study was to analyze the seasonal variation of Schinus terebinthifolius aqueous extracts and essential oils allelopathic effects on restinga target species (Cereus fernambucensis, Erythroxylum ovalofolium, Pilosocereus arrabidae), a crop species (Lactuca sativa) and itself (autotoxicity). For that, leaves were collected seasonally at restinga de Massambaba for aqueous extract preparation and essential oils extraction. Aqueous extract was obtained by drying the leaves at 60 C, grinding it in a blender, diluted with distilled water and filter, generating 5, 10, 15 and 20% concentrations. Oil extractions were performed by 300 g of fresh leaves hydrodistillation. Essential oil composition was performed by gas chromatography using SPME fiber. The phytotoxic effect was evaluated on germination percentage, speed of germination, hypocotyl and root growth, electrolyte leakage and dry mass of the target species. Aqueous extracts allelopathic effects were observed for all target species, especially for natives. Its effects varied with the seasons, being dose-dependent and species-specific. Schinus terebinthifolius essential oils could also inhibited target species germination and growth. Its effects varied with the seasons and target species. It is suggested that these differences are related to S. terebinthifolius phonological phases and restinga de Massambaba environmental conditions. This phytotoxic effect, if proven in the field, may restrict Schinus terebinthifolius use in habitat restoration
19

Efeito alelopático das folhas de Schinus terebinthifolius Raddi em espécies nativas da restinga de Massambaba / Allelopathic effect of Schinus terebinthifolius leaves on Massambaba restinga native species

Ana Beatriz Romana Viveiros 30 April 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Schinus terebinthifolius Raddi (Anacardiaceae) é uma espécie nativa da América do Sul com grande distribuição geográfica e muito comum em áreas de restinga. Sua grande plasticidade ecológica e boa interação biótica a torna espécie-chave na restauração de ambientes, porém, sua dominância pode estar relacionada à liberação de compostos alelopáticos. O objetivo do estudo foi avaliar o potencial alelopático dos extratos aquosos e óleos essenciais de folhas de Schinus terebinthifolius nas diferentes estações do ano sobre espécies-alvo nativas da restinga (Cereus fernambucensis, Erythroxylum ovalofolium, Pilosocereus arrabidae), uma espécie agrícola (Lactuca sativa) e nela própria (autoalelopatia). Para isso, suas folhas foram coletadas sazonalmente na restinga de Massambaba para o preparo dos extratos aquosos e extração dos óleos essenciais. Os extratos aquosos foram obtidos através da secagem das folhas a 60 C, trituração em liquidificador, diluição em água destilada e filtração, obtendo as concentrações de 5, 10, 15 e 20%. As extrações dos óleos foram realizadas através da hidrodestilação de 300 g de folhas frescas. A análise da composição dos óleos essenciais foi realizada através de cromatografia gasosa utilizando fibra SPME. O efeito fitotóxico foi avaliado nas espécies-alvo através da porcentagem de germinação, velocidade de germinação, crescimento aéreo e radicular, condutividade elétrica e massa seca. O efeito alelopático dos extratos aquosos foi observado em todas as espécies-alvo, principalmente sobre as espécies nativas. Esse efeito variou nas estações do ano de forma dose-dependente e espécie-específica. Os óleos essenciais de S. terebinthifolius também foram capazes de inibir a germinação e crescimento das espécies-alvo, e, da mesma forma que os extratos aquosos, esses efeitos variaram nas estações do ano e para cada espécie. Sugere-se que essas diferenças estejam relacionadas às fenofases de S. terebinthifolius e condições ambientais da restinga. Esse efeito fitotóxico, se comprovado em campo, pode restringir a utilização de S. terebinthifolius na restauração de ambientes. / Schinus terebinthifolius Raddi (Anacardiaceae) is a South America species with large geographical distribution, being common in Coastal Sandy Banks areas. Its ecological plasticity and good biotic interactions makes it a key specie in habitat restoring, but its dominance may be related to the release of allelopathic compounds. The objective of the study was to analyze the seasonal variation of Schinus terebinthifolius aqueous extracts and essential oils allelopathic effects on restinga target species (Cereus fernambucensis, Erythroxylum ovalofolium, Pilosocereus arrabidae), a crop species (Lactuca sativa) and itself (autotoxicity). For that, leaves were collected seasonally at restinga de Massambaba for aqueous extract preparation and essential oils extraction. Aqueous extract was obtained by drying the leaves at 60 C, grinding it in a blender, diluted with distilled water and filter, generating 5, 10, 15 and 20% concentrations. Oil extractions were performed by 300 g of fresh leaves hydrodistillation. Essential oil composition was performed by gas chromatography using SPME fiber. The phytotoxic effect was evaluated on germination percentage, speed of germination, hypocotyl and root growth, electrolyte leakage and dry mass of the target species. Aqueous extracts allelopathic effects were observed for all target species, especially for natives. Its effects varied with the seasons, being dose-dependent and species-specific. Schinus terebinthifolius essential oils could also inhibited target species germination and growth. Its effects varied with the seasons and target species. It is suggested that these differences are related to S. terebinthifolius phonological phases and restinga de Massambaba environmental conditions. This phytotoxic effect, if proven in the field, may restrict Schinus terebinthifolius use in habitat restoration
20

Efeito da variação sazonal na produção de compostos ativos em Tithonia diversifolia (HEMSL) Gray, utilizando ensaio com microrganismos. / Effects of seasonal variation upon production of active compounds in tithonia diversifolia (HEMSL) Gray using microrganisms bioassay.

Paula Carolina de Simoni Cordeiro e Silva 13 August 2004 (has links)
A variação sazonal na produção de compostos secundários em Tithonia diversifolia (Hemsl) Gray foi investigada desde a primavera de 2002 até o inverno de 2003. Coletas bimensais foram realizadas com posterior extração e fracionamento do material vegetal (folhas e flores). As amostras foram monitoradas por CCD e analisadas quanto a atividade antimicrobiana contra Staphylococcus aureus, Escherichia coli, Salmonella choterasuis e Pseudomonas aeruginosa, pelo método de microplaca. Os perfis cromatográficos foral distintos para as diferentes épocas do ano, sendo evidenciada a presença de um grupo de substâncias em maior quantidade no mês de Abril de 2003 (outono), período de pré-florada desta espécie. Os extratos foram ativos para apenas dois microrganismos dentre os quatro testados. Algumas frações apresentaram CIM (concentração inibitória mínima) significativa (<1mg/mL). / The seasonal variation upon production of active compounds in Tithonia diversifolia (Hemsl) Gray was investigated from spring of 2002 until winter of 2003. Leaf samples were collected every three months for posterior extraction and analysis . The samples were monitored by Thin Layer Chromatography (TLC) and analyzed for anti-microbial activities on Staphylococcus aureus, Escherichia coli, Salmonella choterasuis and Pseudomonas aeruginosa, using micro-plate method. The TLC results showed a clear accumulation of active compounds during April . The extracts were active for only two microorganisms of a total of four studied.

Page generated in 0.1152 seconds