• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 111
  • 68
  • 7
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 253
  • 253
  • 112
  • 102
  • 37
  • 37
  • 33
  • 31
  • 31
  • 23
  • 23
  • 23
  • 17
  • 16
  • 14
  • 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.
71

Estudo epidemiológico na população residente na Baixada Santista - Estuário de Santos: avaliação de indicadores de efeito e de exposição à contaminantes ambientais com enfoque em doenças hepáticas / Epidemiological study in Baixada Santista resident population Santos Estuary: evaluating indicators of effects and exposure to environmental contaminants with a focus on liver diseases

Daniele Fernandes Pena Carvalho 30 March 2011 (has links)
A região do Estuário de Santos e São Vicente é alvo da ocupação desordenada e degradação ambiental em decorrência do despejo de toneladas de resíduos tóxicos produzidos por empresas do pólo industrial de Cubatão que contaminam rios, solo, fauna e a população estabelecida próxima a estes depósitos industriais irregulares. O fígado é um dos órgãos que podem ser afetados por estes contaminantes, pois é o local de neutralização de substâncias tóxicas. Este estudo tem como objetivo avaliar prevalência de doenças do fígado e alterações nas enzimas hepáticas bem como indicadores de exposição a poluentes químicos em áreas contaminadas do Estuário de Santos e São Vicente e é parte de um projeto financiado pelo CNPq. Foi adotado o desenho transversal e foram selecionados 820 domicílios em cada uma das quatro áreas do Estuário (Pilões e Água-Fria, Cubatão Centro, São Vicente Continental e Guarujá) e em uma área localizada fora do Estuário (Bertioga). Na primeira fase foi realizado um inquérito de morbidade referida nas áreas selecionadas. O instrumento de coleta de informações foi um questionário estruturado e prétestado. Foram estimadas as proporções das doenças do fígado, hepatite, cirrose e câncer de fígado e vias biliares por área, a associação entre desfechos e áreas e diferenças entre proporções. Foram realizados modelos de regressão logística para investigação de possíveis fatores de risco para as doenças hepáticas. Na segunda fase, em uma amostra dos participantes da primeira fase, foram feitas sorologias para hepatites B e C e dosados os níveis séricos de alanina aminotransferase (ALT ou TGP), mercúrio e chumbo. Modelos de regressão logística foram usados para estimar fatores de risco para alterações enzimáticas. Foi avaliada a associação entre alterações nos níveis da enzima hepática e os níveis de chumbo e mercúrio no sangue. A prevalência de doenças do fígado entre todos os entrevistados foi de 1.5% e de 1.4% entre os sem exposição a produtos químicos e álcool. Entre os que mencionaram presença de doença do fígado, 1/3 dos que relataram ter hepatite e metade dos que relataram ter outras doenças do fígado, não apresentaram as duas exposições. Nesta mesma amostra, hepatite foi a doença mais relatada e houve associação estatística entre residir em Pilões e Água-Fria e ter hepatite (p = 0,001). O consumo de produtos alimentícios produzidos localmente (frutas) (RC = 3,91; IC95%: 1,70 8,99) e de água de fontes locais (RC = 4,44; IC95%: 1,73 11,40) mostraram-se fatores de risco para doenças hepáticas. A proporção de alterações nos níveis de alanina aminotransferase (ALT ou TGP) foi de aproximadamente 11%. O IMC elevado apresentou-se como fator de risco para a presença de alteração na enzima hepática (RC = 2,8; IC95%: 1,25 6,27). Entretanto, 20% dos indivíduos com ALT elevada apresentavam IMC normal e sorologia para hepatites B e C negativas. Nesta mesma amostra não houve associação entre concentrações de metais no sangue e níveis séricos de ALT. Estes resultados indicam que a exposição ambiental através de rotas de contaminação atuais ainda é um claro problema de saúde pública na região estuarina de Santos e São Vicente. / The Santos and Sao Vicente estuary region is the scene of unplanned occupation and environmental degradation due to the dumping of toxic waste tons produced by companies in the industrial hub of Cubatão that contaminate rivers, soil, fauna and people close to these irregular industrial deposits. The liver is an organ that may be affected by these contaminants once it is the local for neutralization of toxic substances. This study aims to evaluate the prevalence of liver disease and abnormal liver enzymes as well as indicators of exposure to chemical pollutants in contaminated areas of the estuary of Santos and São Vicente and is part of a project financed by CNPq. It was adopted a cross sectional design and were selected 820 households in each of the four areas of the estuary (Pilões Água Fria, Cubatão Center, Continental São Vicente and Guarujá) and 820 households in an area outside the estuary (Bertioga). In the first phase a survey of referred morbidity was carried out in the selected areas. The information collection instrument was a structured and pre-tested questionnaire. We estimated the proportions of liver disease, hepatitis, cirrhosis and cancer of both liver and biliary tract by area, the association between outcomes and areas and differences between proportions. We performed logistic regression models to investigate possible risk factors for liver disease. In the second phase, in a sample of participants from the first phase, we carried out hepatitis serology (B and C) and measured serum levels of alanine aminotransferase (ALT or SGPT), mercury, and lead. Logistic regression models were used to estimate risk factors for enzyme abnormal levels. We evaluated the association between changes in liver enzyme levels and blood lead and mercury levels. The prevalence of liver disease among all respondents was 1.5% and 1.4% among those without exposure to chemicals and alcohol. Among those who mentioned the presence of liver disease, 1/3 of those who reported having hepatitis and half of those who reported having other diseases of the liver did not present the two exposures. In the same sample, hepatitis was the most prevalent disease and it was observed statistical association between living in Pilões Água Fria and having hepatitis (p = 0.001). The consumption of locally produced food products (fruits) (OR = 3.91, 95% CI 1.70 to 8.99) and water from local sources (OR = 4.44, 95% CI: 1.73 - 11 40) were risk factors for liver diseases. The proportion of participants with high levels of alanine aminotransferase (ALT or SGPT) was approximately 11%. Increased BMI was presented as a risk factor for the alterations in liver enzyme (OR = 2.8, 95% CI: 1.25 - 6.27). However, 20% of individuals with elevated ALT had a normal BMI and negative serum tests for hepatitis B and C. In the same sample there was no association between ALT serum concentrations and blood metals levels. These results indicate that exposure through environmental contamination routes is still present and it is a clear public health problem in the estuary of Santos and São Vicente.
72

Estudo de Tilápias do Nilo (Oreochromis niloticus) como bioindicadores da poluição por mercúrio nos lagos do Parque Ibirapuera e do Parque Ecológico do Tietê na Grande São Paulo / Study on Nile Tilapia (Oreochromis niloticus) as mercury pollution bioindicators at Parque Ibirapuera and Parque Ecológico do Tietê lakes at Greater São Paulo

Maria Eugenia Carretero 17 December 2012 (has links)
A Grande São Paulo, composta por 39 municípios, apresenta crescimento urbano e industrial expoente que contribuem para o constante acúmulo de poluentes no ambiente. Ainda assim, exibe áreas verdes remanescentes que contribuem para a sustentabilidade ambiental da cidade, como por exemplo, o Parque Ibirapuera e o Parque Ecológico do Tietê. Nesse contexto, o presente estudo visa verificar a viabilidade em utilizar as O. niloticus como bioindicadoras da poluição por mercúrio no ecossistema aquático dos dois parques da Grande São Paulo. Obteram-se para as tilápias do Nilo do Parque Ibirapuera pertencentes aos pontos de coleta A, B e C durante o inverno as respectivas concentrações de mercúrio total no sangue 2,72±4,20µg/L, 2,45±1,90µg/L e 1,19±0,05µg/L e, no hepatopâncreas as respectivas concentrações de mercúrio de 0,07±0,02 µg/g, 0,06 ±0,005 µg/g e 0,16 ±0,07 µg/g. No verão as tilápias do Parque Ibirapuera apresentaram nos mesmos pontos de coleta as respectivas concentrações de mercúrio total no sangue 2,50±0,84µg/L, 2,67±1,03µg/L e 2,430±0,790µg/L e, no hepatopâncreas as respectivas concentrações de mercúrio de 0,08 ±0,03 µg/L, 0,16 ±0,10 µg/L e 0,09 ±0,03 µg/L. Os peixes do Parque Ecológico do Tietê pertencentes ao ponto de coleta B durante o inverno e verão apresentaram no hepatopâncreas as concentrações de mercúrio total de 0,08±0,01µg/g e 0,10±0,0µg/g e, no sangue as concentrações e mercúrio de 3,59 µg/L e 2,00±1,00 µg/L. A análise estatística de regressão linear foi negativa, alta e com significância estatística apenas entre a idade estimada e a concentração do mercúrio no sangue sugerindo que as tilápias jovens são mais susceptíveis ao acúmulo de mercúrio. Viabilizou-se através deste estudo o uso das tilápias do Nilo como bioindicadores para a poluição por mercúrio nos lagos dos parques da Grande São Paulo. / The Greater São Paulo, formed by 39 cities, presents high urban and industrial growth that contribute to environmental pollution accumulation. In contrast, the same area has residual green areas that contributes to the city\'s environmental sustainability, such as Parque Ibirapuera and Parque Ecológico do Tietê. This study intends to verify the feasebility of using O. niloticus as bioindicators of mercury pollution on the aquatic ecosystem of two Greater São Paulo parks. At winter, on Parque Ibirapuera, the collected Nile Tilapia presented 2,72±4,20µg/L, 2,45±1,90µg/L e 1,19±0,05µg/L mercury concentration on blood and 0,07±0,02 µg/g, 0,06 ±0,005µg/g e 0,16 ±0,07 µg/g mercury concentration on liver for collect points A, B and C respectively. At summer, Nile Tilapias collected on the same three points, presented 2,50±0,84µg/L, 2,67±1,03µg/L e 2,430±0,790µg/L mercury concentration on blood and 0,08 ±0,03 µg/L, 0,16 ±0,10 µg/L e 0,09 ±0,03 µg/L on liver. The Parque Ecológico do Tietê\'s fish, from point B, presented 0,08±0,01µg/g mercury concentration on liver and 3,59 µg/L mercury concentration on blood. At summer, the mercury concentrations were 0,10±0,0µg/g on liver and 2,00±1,00 µg/L on blood. The linear regression statistical analisys was negative, high and with statistical significance only between estimated age and blood mercury concentration, indicating that young tilapia are more likely to accumulate mercury. The use of Nile Tilapia as bioindicators for mercury pollution on Greater São Paulo\'s park lakes was made viable through this study.
73

Mobilização de poluentes no maciço de resíduos de lixão desativado / Mobilization of pollutants in waste mass of an uncontrolled landfill

Shinzato, Marjolly Priscilla Bais 19 September 2014 (has links)
O lançamento dos efluentes de depósitos de resíduos no ambiente altera significativamente a qualidade das águas. Apesar do amplo acervo de dados sobre os mecanismos de formação do lixiviado e das mudanças de sua qualidade nas diferentes fases do aterro, pouco se sabe sobre os mecanismos de mobilização de poluentes do maciço de resíduos para o lixiviado e da interação deste com as águas subterrâneas e o meio geológico. A compreensão destes processos é essencial para orientar critérios de estabilidade destes aterros e para avaliar se o maciço de resíduos não representa mais uma ameaça para o ambiente. Nesse sentido, um poço de 1,5 m de diâmetro com lisímetros de sucção instalados em diferentes profundidades foi instalado dentro do maciço de resíduos do lixão desativado de São Carlos/SP para análise do conteúdo aterrado e do lixiviado em camadas de resíduos com diferentes idades de deposição. Amostras de águas subterrâneas coletadas em poços de monitoramento a montante, dentro e a jusante do maciço também foram analisadas. Concluiu-se que o lixão está na fase metanogênica e que o maciço é composto por chorume imóvel com elevadas concentrações de poluentes e por resíduos não inertes. Condições redutoras e de tamponamento são mantidas constantes no lixão, as quais controlam as reações redox ocorrentes no maciço e a qualidade do lixiviado. A mobilização de Fe, Ca, Mg, K, Na, Ni, Zn, Pb e Cd do maciço para o lixiviado apresentou-se mais significativa sobre os demais elementos avaliados e ocorre a partir dos resíduos sólidos aterrados e dos solos de cobertura. Os principais parâmetros de interesse ambiental identificados no lixiviado foram nitrogênio amoniacal, Cd, Cr, Pb, NO3 e DBO5 e nas águas subterrâneas foram nitrogênio amoniacal, Cr, Cd, Al, Ni, Fe, Mn e Pb. A análise dos dados de qualidade do conteúdo aterrado e do lixiviado comprovou uma significativa mobilização de poluentes dentro do maciço de resíduos do lixão desativado de São Carlos/SP. Apesar de estar desativado há 18 anos, o maciço de resíduos ainda é fonte primária de poluentes, comprovando seu potencial remanescente de contaminação, principalmente para as águas do Sistema Aquífero Guarani (SAG) e do manancial Ribeirão do Feijão. Portanto, o monitoramento da área não pode ser descontinuado. / The effluent release of waste disposal sites in the environment alters significantly the water quality. Despite the large collection of data about leachate formation mechanisms and its quality changes in the different landfill phases, very little is known about pollutants mobilization in solid waste of an uncontrolled landfill and its interaction with groundwater and geological environment. Understanding these processes is essential to guide stability criteria for these landfills and to assess whether the waste mass no longer represents a threat to the environment. Thus, a dug well with 1.5 meter diameter equipped with suction lysimeters in different depths was installed within the solid waste mass of the uncontrolled landfill of São Carlos/SP to analyze the landed content and the leachate in different aged waste layer. Groundwater samples collected at monitoring wells upstream, within and downstream of the massif were also analyzed. It was concluded that the landfill is in methanogenic phase and that the waste body is composed by immobile leachate with high concentrations of pollutants and by non-inert solid waste. Reductive and tamponade conditions are kept constant in the waste mass, which control the redox reactions occurring in the mass and the quality of leachate. The mobilization of Fe, Ca, Mg, K, Na, Ni, Zn, Pb and Cd from the solid waste to the leachate is very significant and occur from the landed solid waste and from the soil cover. The main parameters of environmental interest identified in the leachate were ammonia nitrogen, Cd, Cr, Pb, NO3 and BOD5 and in groundwater were ammonia nitrogen, Cr, Cd, Al, Ni, Fe, Mn and Pb. Data analysis of grounded content quality and leachate quality has proved significant mobilization of pollutants within the waste mass of uncontrolled landfill of São Carlos. Despite being deactivated 18 years ago, the waste mass is still a primary source of pollutants, proving its remaining potential contamination, mainly for water of Guarani Aquifer System (SAG) and of Ribeirão do Feijão river. Therefore, monitoring of the area can not be discontinued.
74

An Examination of Factors Impacting Managerial Behavior towards Compliance Controls: Impact of the EPA Audit Policy

Unknown Date (has links)
The United States established the Environmental Protection Agency (EPA) to monitor and enforce compliance with environmental pollution standards through various programs and policies. One such policy, the Audit Policy, allows companies to voluntarily self-report violations to the Agency in exchange for elimination of certain penalties. Despite the policy, firms still incur large environmental penalties, thus indicating the need for better understanding of the policy. A necessary but not sufficient condition for penalty relief under the Audit Policy requires discovery of violations by an environmental audit or a compliance management system. This research explores the option of discovery by a compliance management system and examines the motivation of managers to invest in an environmental management system (EMS). The theory of reasoned action (TRA) argues that attitude and subjective norms precede intentions. I use this theory to investigate what factors cause a manager to invest in an environmental management system (EMS). Additionally, I examine whether environmental attitude, tolerance for ambiguity and willful blindness are antecedents to attitude towards an EMS. In this study, I develop and test a scale of the willful blindness construct and measure its impact on managerial decision-making. The willful blindness construct development produced a one-item measure. My results support all hypotheses except for the predicted link between tolerance for ambiguity and attitude. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
75

Screening, isolation and purification of bioactive compounds with antibacterial activity against mycobacterium smegmatis

Mmushi, Tshepo Joseph January 2011 (has links)
Thesis (M.Sc. (Microbiology)) --University of Limpopo, 2011 / The leaves of fifteen plant species were collected from the Lowveld Botanical Garden in Nelspruit, Mpumalanga Province, South Africa. The collection was based on a list of plants and their ethnopharmacological information provided by the Phytomedicine Programme at the University of Pretoria. The dried leaves of the plants were powdered and extracted using hexane, dichloromethane, acetone and methanol. The extracts were screened for antibacterial activity against Mycobacterium smegmatis and Rhodococcus erythropolis. The acetone extract of Milletia stulhimannii was the most active, showing activity against Mycobacterium smegmatis and Rhodococcus erythropolis with MIC values 0.13 and 0.08 mg/ml, respectively. Acetone extracts for all plants had the lowest MIC values ranging between 0.11-1.25 mg/ml and 0.08-1.25 mg/ml for M. smegmatis and R. erythropolis, respectively. Milletia stulhimannii, Albizia gummifera, Xanthocercis zambesiaca and Barringtonia racemosa extracts have shown the greatest potential for anti-tubercolosis agents. These were all active against M. smegmatis with an average MIC value of acetone extracts of 0.13 mg/ml. Apodytes dimidiata was selected for the isolation of active compounds since its activity on qualitative antibacterial activity assays was highly prominent on TLC plates in comparison to the other plant extracts. Two compounds were isolated from A. dimidiata but after purification, their MICs were above 2.5 mg/ml indicating a possible loss of activity during purification. The preliminary NMR spectra analysis suggested that the compounds were a long fatty acid and a triterpene. Future work is required to elucidate the chemical structures of the latter compounds and to test the activity of these compounds against Mycobacterium tuberculosis. / Department of Water Affairs, and University of Limpopo Research Development and Administration Office
76

Bioassay assessment of mine pit lake water for aquaculture and biodiversity conservation

Neil, Luke L January 2007 (has links)
For decades, researchers have been working to better understand the effects of acid and metal toxicity to aquatic organisms and to develop ways to effectively mitigate these detrimental effects. Acid mine drainage (AMD) causes environmental pollution that affects many countries having historic or current mining industries. Both surface and underground mining have the potential to create AMD and therefore adversely affect the local and adjacent environments. Through malignant mining and farming practices, damming rivers and the changing climate, surface freshwater resources are rapidly being reduced in Australia. Mine pit lakes offer a large freshwater resource that if managed correctly may sustain significant environmental, social and economic benefits from selected end uses for the future. However, assessment of mine pit lakes needs to be achieved to validate end use options. The Collie Basin located in the southwest of Western Australia is a coal mining area with many abandoned open cast mines (OCM). Some of these OCM have filled with water forming mine pit lakes that are affected by AMD. The result is large freshwater bodies with moderate to high concentrations of metals and a low pH. High concentration of metals combined with low pH is of environmental concern to both the aquatic and terrestrial ecosystem. Nevertheless, remediation techniques for AMD are available and applicable to these acidic lakes. However, the lakes in the Collie Basin are low in sulphatic compounds, therefore, restricting the use of the most common remediation treatment of bioremediation with sulphate reducing bacteria. Three remediation treatments were assessed for there efficacy in toxicity amelioration to three mine pit lakes. The treatments assessed were Limestone addition, phosphorus addition and a Rapid Catalytic Oxidation (RCO) treatment. / Toxicity assessment was achieved by means of comparing physico-chemical data to guideline trigger values and biological assessment. Biological assessment was achieved with three commonly used but ecologically and geographically relevant species. The bioassay species were the alga Chlorella protothecoides, the crustacean Ceriodaphnia cf dubia and the protozoa Tetrahymena thermophila. Aquaculture is being trialled adjacent to one of the pit lakes in limestone treated mine pit lake water. Therefore, the aquaculture fish species Bidyanus bidyanus early life stages were also used to assess residual toxicity from treated mine pit lake water. Limestone remediation of pit lake water demonstrated good reduction of dissolved metal concentrations with the exception of Zn and the ability to increase pH to circum-neutral. Biological assessment of limestone treated pit lake water showed that toxicity was removed to the three bioassay species and to the aquaculture species B. bidyanus early life stages. A larger field- scale mesocosm experiment with limestone treatment in situ is recommended. Assessment of the mesocosm experiment with biological and chemical analysis will confirm the efficacy of this treatment for full scale use.
77

Determination Of Ambient Levels And Sources Of Volatile Organic Compounds In Izmir-aliaga Region

Dogan, Guray 01 January 2013 (has links) (PDF)
In this study, atmospheric levels and sources of VOCs at Aliaga industrial area was investigated. For this, VOC concentrations were measured at two monitoring stations through winter and summer campaigns in 2005 and 2006. Sampling stations were located in downtown Aliaga and downwind of industrial facilities, approximately 500 m to the south east of Horozgedigi village. After the summer sampling, another temporary station was installed in between PETKIM and T&Uuml / PRAS, named as T&Uuml / PRAS Station to generate T&Uuml / PRAS and PETKIM profiles. More than 50 species were measured in all stations. In all stations, toluene has the highest contribution to total VOC concentration. Toluene is followed by m,p-xylene and benzene. While higher concentrations of traffic related VOCs were measured at Aliaga station, VOCs from industrial solvents and industrial processes were higher at Horozgedigi station. The concentration levels in Aliaga and Horozgedigi are found to be comparable to the other industrial regions reported in the literature. Investigation of episodes, diurnal variations of VOCs and meteorological parameters showed that PETKIM and T&Uuml / PRAS emissions affect the concentrations levels at Horozgedigi and Aliaga stations. Source profiles of PETKIM and T&Uuml / PRAS are determined by using the T&Uuml / PRAS station data set. 2-methyl-hexane, benzene and 2,2,3-tri-methyl-butane+2,3-di-methyl-pentane are found to be good markers of PETKIM emissions. Ten different VOC sources were identified in the region. These were gasoline exhaust, diesel exhaust, natural gas use, gasoline evaporation, industrial emissions-1, natural gas construction, non-industrial solvent use, industrial emissions-2, PETKIM emissions, and mixed emissions from PETKIM and shipbreaking facilities.
78

The problem of the environmental pollution and the development of environmental industry in China

Tsai, Jen-Ni 03 August 2006 (has links)
The purposes of this thesis are probing into the pollution problems of the environment in China and the development of environmental industry. Simultaneously, to acquaint myself with the extent of the environmental pollution in China; and why China develop the environmental goods and services industry , and how the China government practice the strategy of environmental protection industry. Bye means of this study that aimed at the analysis structure of the amendment of China¡¦s peculiarity, we will be able to understand the present situation and orientation of the development of environmental industry in China; and further, by clarifying the relationships among central government , local government and environmental industry, to search out the key factors and the development models of influence upon the development of environmental industry; in Addition, to conclude what the real necessary business items and which areas will be beneficial for the investment of foreign environmental enterprises in China. In the meanwhile, analyzing the opportunities and threat to the environmental industry in China , which will be conducive to the foreign capital to frame the strategy of investment.
79

Modeling The Water Quality In Uluabat Lake

Yenilmez, Firdes 01 July 2007 (has links) (PDF)
Lakes can be used for recreational purposes, agricultural irrigation, domestic water supply or industrial use. However, these functions of the lakes can be impaired due to excess nutrient loadings from industrial facilities, agricultural activities, and discharge of wastewaters from sewage systems. Uluabat Lake is one of the important lakes in Turkey faced with water quality problems due to excess nutrient loading from point and non-point sources. In this study, Water Quality Analysis Simulation Program (WASP Version 7.2), supported by the Environmental Protection Agency (EPA), was used to simulate the water quality of the lake. The model was calibrated using a set of data belonging to the time period from January 1st to June 1st, 2000, for dissolved oxygen (DO), chlorophyll-a (Chl-a), ortho-phosphate (PO4-P) and nitrate (NO3-N). An acceptable similarity was obtained between the predicted and observed water quality values in calibration. Then, the model was verified for another data set. Verification period was from 1st of June to 31st of December, 1999. Verification results were also coherent with the observed values. Following the calibration and verification, the model was used as a management tool to predict the future quality conditions for the lake for different management scenarios. According to the results, sediment dredging had a significant impact on the water quality. Additional methods on top of sediment dredging improved the quality of the lake. The best result was obtained when buffer zone was formed, phosphorus loads from the MustafakemalpaSa District sewage system and Emet and Orhaneli Watersheds were decreased by 50% and 50% decrease was considered in the fertilizer usage throughout the agricultural lands, in addition to sediment dredging.
80

Development Of Paper Type Tyrosinase Biosensor

Senyurt, Ozge 01 May 2008 (has links) (PDF)
Phenolic compounds are the chemicals which are used by many different industries and as a result of this spread to the environment. These compounds can be absorbed easily through the human and animal skin and through the mucosal membrane, mix in to the blood circulation and thus create a toxic effect on several tissue and organs including, liver, lung and kidneys. For this reason, determination of phenolic compounds emitted to environment is a very important issue. In fact, there are standard methods for the determination of these compounds like HPLC, Spectrophotometric and calorimetric methods however, these are time consuming methods and requires to be expertise. On the other hand, there are also different types of biosensors developed for the phenolic compound detection. In this study, a new, disposable, cheap and convenient tyrosinase biosensor was developed for the phenolic compound detection. By means of absorption method, the enzyme tyrosinase and the chromophore MBTH were immobilized on the support material and as a model substrate L- dopa was used. As a result of optimization studies 1mg/ml tyrosinase concentration and 1.5mM MBTH concentration were determined for using in biosensor construction. Detection limit of l-dopa, model substrate, found as 0,064 mM and for other phenolic compounds, 4-chlorophenol, catechol, m-cresol and p-cresol, detection limit was obtained 0.032 mM, 0.032 mM, 0.128 mM, 0.128 mM, respectively. In addition, we found that the biosensor response was not affected by pH changes ranging from 3 to 11. The stability of biosensor which is one of the important parameter for commercialization was not change through 70 days at room temperature and 4&deg / C when compared to at the beginning response.

Page generated in 0.1026 seconds