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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.
101

Metal removal from contaminated soil by hyper-accumulating plants : effects of repeated croppings

Bricker, Timothy J. January 2000 (has links)
Phytoremediation, i.e., the use of plants to clean up contaminated soil, may serve as a feasible alternative if a high-biomass crop can be found that accumulates metals to a high.degree. Two plant species, corn (Zea mays) and Indian mustard (Brassica juncea), were grown in soil from a Superfund site contaminated with Pb and Cd (PbTota, = 65,200 mg/kg and CdTotI = 52 mglkg) over two croppings. Soil treatments consisted of composted sewage sludge (CSS), ethylenediaminetetraacetic acid (EDTA), and sodium citrate at two concentrations. In most cases, the EDTA and citrate treatments were superior in terms of extracting soil Pb into root tissue, and translocation of Pb into aboveground biomass. The CSS treatment typically resulted in the lowest Pb removal efficiencies. The high pH (7.4) and high exchange capacity of the CSS may have immobilized soil Pb. Soil Cd was generally more mobile than soil Pb. The EDTA2 treatment was most effective in removing soil Pb into roots, and translocation to shoots. Lead remaining in the soil after two croppings was mainly associated with the carbonate, organic, and residual fractions, which represent the less bioavailable form of this metal. / Department of Natural Resources and Environmental Management
102

Field scale phytoremediation trials of lead and cadmium-contaminated soil

Hee, Calvin K. January 2005 (has links)
There is an ever-increasing need to address problems associated with the creation and disposal of wastes which result from human activities. Pb and Cd contamination is a common problem at many abandoned and uncontrolled commercial and industrial sites. Phytoremediation is one technology that can be employed to remove metals such as Pb from the soil. This study investigated the effectiveness of several plant and soil treatments on the uptake and retention of Pb and Cd by vegetation from contaminated soil at a Superfund site. Field plots were established and plant treatments included a mixture of grasses including Festuca, Poa. and Phleum; red clover (Trifolium Pratense); and sunflower (Helianthus annuus). Soil treatments included a common NPK fertilizer, ethylenediaminetetraacetic acid (EDTA), dilute sulfuric acid (H2SO4), and a mixture of EDTA and H2SO4 (EDTA+H2SO4). Trifolium tissue contained a greater quantity of Pb (182 mg Pb/kg tissue) than that of Poa (65 mg Pb/kg tissue). Cadmium concentration was similar in Poa and Trifolium tissue. ranging from 7.2 to 10.6 mg/kg tissue. Different soil treatments affected Pb levels found in plant tissue in order of effectiveness: H2SO4>EDTA>NPK>EDTA+H2SO4 The effects of soil treatments on Cd levels were similar to those for Pb with a difference of 0.1 mg Cd/kg tissue between EDTA and NPK treatments. Soil amendments differentially influenced Pb bioavailability and uptake, with H2SO4 exhibiting the greatest positive influence on Pb and Cd concentration in tissue. There was no correlation between the quantity of Pb and Cd up taken by vegetation at the site. The current study demonstrated the capability of common native plant species to grow on toxic and infertile soils, and the ability to uptake Pb and Cd to a limited degree. Regardless of tissue concentrations of Pb or Cd, Poa coverage at the site was generally dense. demonstrating the ability of Poa to become established on toxic soils and prevent soil erosion. / Department of Natural Resources and Environmental Management
103

Effects of various diets on vitamin B-6 and cholesterol levels in ten men aged 21-37

Powell, Lisa January 1990 (has links)
Vitamin B-6 is a vitamin often promoted by the popular press as a cure all. It's role is also being studied in regard to pre-menstrual syndrome, myocardial infarction and alterations in lipid and fatty acid metabolism. This study was designed to investigate whether there was a difference between vitamin B-6 blood levels, during a baseline study, a period of vitamin B-6 depletion and vitamin B-6 supplemention in ten men ages 21-37. The effect of each diet on total cholesterol was also investigated.The experimentally accessible population for this study Laboratory as part of a larger study conducted by Dr. Stephen Coburn of the Fort Wayne State Developmental Center.Analysis of the data indicated:1) A significant difference between red blood cell pyridoxal phosphate and blood plasma levels of vitamin B-6 during the baseline, depletion and supplementation phases in ten men 21-37.2) Total serum cholesterol levels fell significantly through all phases of the study. High density lipoproteins fell significantly during the depletion phase but did not rise significantly during the supplementation phase. Low density lipoproteins showed no significant difference during the three phases of the study. When dietary records were evaluated mean dietary intake during the baseline and supplementation phases of the diet met the Recommended Dietary Allowance (RDA) for vitamin B-6. Mean protein intake also met the RDA with 102.1 grams during the baseline phase and 106.1 grams during the supplementation phase. These intakes are consistent with those found in previous studies conducted by the USDA. Mean intake of fat was lower than the 30 percent of calories recommended by the American Heart Association but wide variation existed among subjects.No physical symptoms of vitamin B-6 deficiency manifested themselves during the study. Subjects reported no other problems associated with low vitamin B-6 intakes.The data indicated that vitamin B-6 intake effects the amount of red blood cell plasma pyridoxal phosphate and plasma vitamin B-6. No clear effect can be found between vitamin B-6 intake and serum cholesterol levels. "Normal" diets also appeared to provide adequate vitamin B-6 to meet both RDA's and somatic needs. Wide variation seems to exist, however, among individuals. / Department of Home Economics
104

Nonstarch polysaccharide fractions of raw, processed and cooked carrots

Kim, Sooyoun 18 May 1994 (has links)
The total and soluble nonstarch polysaccharide (NSP) components of raw, processed (canned and frozen) and home-cooked (boiled) Royal Chantenay carrots have been analyzed. NSP fractions were characterized by separation and summation of the monosaccharides resulting from acid hydrolysis of the parent polysaccharides. Total NSP was primarily composed of glucose, ~37%, and uronic acid, ~35%, containing polysaccharides. Soluble NSP was composed of >50% uronic acids. Processing and simulated home-cooking of raw carrots resulted in an increase in the amount of NSP/unit dry weight. Relative to raw carrots, cooking of canned product resulted in the largest (~2-fold) increase in total and soluble NSP/unit dry weight. Relative differences in NSP were not as great when compared on a wet weight basis. / Graduation date: 1995
105

Adsorption, denitrification, and movement of applied ammonium and nitrate in Hawaiian soils / Applied ammonium and nitrate in Hawaiian soils

Balasubramanian, Vethaiya January 1974 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1974. / Bibliography: leaves 160-167. / xiv, 167 leaves ill
106

Phenolic content and antioxidant activity of South African sorghums and of flours and cookies made from them

Chiremba, Constance 30 November 2009 (has links)
Amongst cereals, sorghum is one of the major sources of phenolic compounds. South African cultivars have not been profiled for their phenolic content and antioxidant activity to highlight their potential benefits. Thus, South African sorghum cultivars representing different sorghum types were evaluated for total phenolic content, condensed tannin content and antioxidant activity and the effect of cultivar on their antioxidant activity. The presence of phenolic antioxidants in the different sorghum cultivars, created an opportunity to develop a sorghum product as a vector of the antioxidants. Cookies were a product of choice due to their shelf stability and high nutrient density. Sorghum cookies were produced from 70%, 90% and 100% extraction rate flours. The effects of flour extraction rates and cultivar on the total phenolic content, condensed tannin content and antioxidant activity of the cookies were determined. Consumer sensory evaluation was used to evaluate sorghum cookie acceptability against a wheat flour cookie. Total phenolic content of the cultivars, determined by the Folin-Ciocalteu method was 0.20 to 1.42 g catechin equivalents (CE)/100 g. The total phenolic content was 3 to 7 times higher in condensed tannin cultivars than in tannin-free cultivars. Using the modified Vanillin-HCl method, condensed tannins were only measurable in the condensed tannin cultivars. They ranged between 5.16 and 8.39 g CE/100 g. Subsequently, the antioxidant activity of the condensed tannin cultivars measured by the ABTS radical scavenging assay was up to 4 times higher than in the tannin-free cultivars. The high phenolic content and antioxidant activity of condensed tannin cultivars was attributed to the contribution of condensed tannins. Therefore, condensed tannin cultivars are a major source of antioxidants compared to tannin-free cultivars. For each sorghum cultivar, cookies of 100% extraction rate flours had 2 to 3 times higher total phenolics compared to those of 70% extraction rate flours, while antioxidant activity was 2 to 10 times higher. Cookies of the condensed tannin sorghum had 2 to 5 times more phenolics compared to those of condensed tannin-free sorghum. Antioxidant activity was 145 to 227 ìMol Trolox equivalents (TE)/g in cookies of condensed tannin sorghum compared to 10 to 102 ìMol TE/g in those of condensed tannin-free sorghum. Processing sorghum flours to cookies seemed to reduce phenolic and antioxidant activity, but considering the flour component in the formula, cookie antioxidant activity was slightly higher than that of flours. The texture of all sorghum cookies was less acceptable compared to that of wheat cookies. The consumers showed a slight overall liking of the condensed tannin-free sorghum and wheat flour cookies. The cookies from condensed tannin flours were neither liked nor disliked. Since generally wheat flour is used for making cookies, the similarities in the overall liking of the condensed tannin-free sorghum cookies and the wheat flour cookies indicate strong potential of sorghum flour for cookie making. Therefore, sorghum cookies have a potential as a functional ready-to-eat snack, with target consumers such as school children in feeding schemes to improve their health and nutrition status. / Dissertation (MSc)--University of Pretoria, 2009. / Food Science / unrestricted
107

Carbon and nitrogen transformations in some forest floors

Lacelle, Larry E. H. January 1971 (has links)
An incubation technique was used to examine carbon mineralization and inorganic nitrogen accumulation in samples of Douglas-fir and alder forest floors developed over soils derived from granitic, ultrabasic and limestone parent materials in western British Columbia and Washington. Samples included L, F, and H or Hi horizons of Douglas-fir mor, raw moder, mull-like moder and mull forest floors and alder typical moder forest floors. Carbon dioxide production by the forest floor materials provided an estimate of gross carbon mineralization and an approximate indication of gross nitrogen mineralization. Comparison of inorganic nitrogen accumulated and gross carbon mineralized indicated that a large fraction of the mineralized inorganic nitrogen is immobilized by the microbial population and (or) lost to denitrification. The Hi horizons (organic horizons containing considerable incorporated mineral matter) accumulated more inorganic nitrogen than did the L and F horizons. Alder forest floors accumulated more inorganic nitrogen than did Douglas-fir forest floor materials. Alder L horizons tended to accumulate ammonium nitrogen while the F and Hi horizons accumulated nitrate nitrogen. Douglas-fir mor forest floors were distinguished from their mull and moder counterparts by slower decomposition and less inorganic nitrogen accumulation, and by largely accumulating ammonium nitrogen in all horizons. Irregular nitrogen accumulation curves, for some samples of Douglas-fir L and F horizons were probably due to denitrification losses. Incubation conditions favoring nitrification, with no plant sinks to remove accumulated inorganic nitrogen, may have favored denitrification losses. / Land and Food Systems, Faculty of / Graduate
108

Problematika obsahového webu / The Issue of Content-Based Website

Sova, Martin January 2012 (has links)
The theme of the present thesis is a content-based website. The paper defines the concept presented on a model of layers functioning content-based website and analyses its functioning from the perspective of systems theory on the basis of identified major transformation functions bound to the operation of the web content. The reader will be acquainted with the model of content distribution on the website and the possibilities of financing its operations. Formulated hypotheses are testing possibilities of return on investment using specific advertising possibilities; validity of these hypotheses is then tested on the data collected during operation of the specific content sites. Than the problem of processes taking place in creating web content is further analyzed. There is a practical example of selection and implementation of an information system built to support the creation of content on a particular website: analyzing operating processes, it describes how the selection of appropriate resources and their deployment is made. The goal of this thesis is to help answer the question whether the operation of the content-based website may be financed by advertising the location of elements, identify what kind of processes are operated in content creation site, and state how to select and implement an information system to support them.
109

Estudo e definição de ontologias como apoio ao desenvolvimento de módulos educacionais / Ontologies study and definition to support the development of educational modules

Joice Basilio Machado 16 April 2012 (has links)
O desenvolvimento de conteúdos educacionais e a adoção de mecanismos de modelagem representam fatores importantes a serem considerados no contexto de ensino e aprendizagem. Nesse cenário, a utilização de ontologias proporciona vantagens tais como definção formal do conhecimento, reusabilidade e interoperabilidade de informações. Além disso, facilidades como recuperação dos objetos de aprendizagem, reúso do conteúdo de aprendizagem e personalização do conteúdo a partir do desempenho do usuário também são observadas. Diante disso, diversas aplicações com base em ontologias têm sido utilizadas tanto para modelar domínios educacionais como para construir, organizar e atualizar objetos de aprendizagem e perfis de aluno. Ainda, associado ao uso de ontologias em sistemas educacionais, verifica-se um crescente interesse na construção da personalização do conteúdo, de acordo com as preferências e características do usuário envolvendo a utilização de ontologias. O presente projeto está inserido nesse contexto, em que um conjunto de ontologias foi desenvolvido para prover a personalização do conteúdo, com base no perfil do usuário. Foi construído um exemplo na ontologia global (que compõe o conjunto de ontologias), em que o domínio de análise de ponto de função foi instanciado para três usuários com diferentes níveis de conhecimento. A ideia é elicitar a granularidade distinta do conteúdo para cada usuário, em conformidade com suas preferências e nível de conhecimento no domínio, a partir das relações e das inferências estabelecidas nas ontologias / The development of didactic material and adoption of modeling mechanisms represent important factors to be considered in the context teaching and learning. In this scenario, the use of ontologies provides advantages such as a formal definition of knowledge, reusability and interoperability of information. Moreover, facilities such as retrieval of learning objects, learning content reuse and customization of content from the user\'s performance are also observed. Therefore, several applications based on ontologies have been used to model so educational domains and to build, organize and update learning objects and student profiles. Also associated with the use of ontologies educational systems, there is an increasing interest in the personalization of the content, according to the user preferences and characteristics, involving the use of ontologies. This project is inserted in this context, where a set of ontologies was developed to provide the personalization of content based on user profile. We constructed an example in the ontology global (which defines the set of ontologies) in the domain of function point analysis was instantiated to three users with different levels of knowledge. The idea is to elicit the distinct granularity of the content for each learner, in accordance with their preferences and level of knowledge in the domain, from the relationships and inferences in the ontologies
110

Development and verification of the commercial value added chain of content marketing response

Hirschfelder, Benedikt 10 May 2019 (has links)
The rapid technological progress in the last 10 years and the coherent opportunities for consumers to communicate among each other almost borderless 24/7, also impacted marketing strategies. Whereas accentuation of product values and pricing are still valuable marketing strategies, consumers are due to the 24/7 access to knowledge, information and consumer feedback, desensitized when it comes to advertising. Availability of the internet across borders, all the time is the main driving factor for marketing practitioners to progressively try to build up a non-purchase pushing relationship to the consumer. With the content communicated in the foreground (informative, helpful or entertaining) and the commercial message in the background this marketing strategy is also known as Content Marketing. Whereas the use of Content Marketing in corporate world is relatively popular, academic research is relatively rare. Indeed, some research was conducted on storytelling and signature stories -a tool of Content Marketing-, however, the functionality of the generic term Content Marketing resembles rather a black box. With the aim to illuminate the understanding and functionality of Content Marketing, this study explored the coherences between content communication vehicles and content generating vehicles. In the scope of this thesis, a theoretical framework conceptualizes the commercial value added chain of Content Marketing response was developed and verified in a business to consumer scenario. This theoretical framework was substantiated with a real world application, more precisely the 'Be More human’ video campaign from the sportswear manufacturer Reebok served as a research object. A non-probability sampling frame, using convenience sampling resulted in a total sample size of 750 respondents. Since this study focused on the development and testing of a theory, partial least square - structural equitation modelling (PLS-SEM) was applied using the software package SmartPLS3. Through the development of the commercial value added chain of Content Marketing response this study exemplifies the commercial content generation process and the content value added by the consumer and thus contributes to a better understanding in academia as well as in corporate world of the complex generic term Content Marketing.

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