No description available.

Abstract Surface water and sediment samples collected from Jukskei River in South Africa, were subjected to different extraction techniques, liquid–liquid (LLE), solidphase extraction (SPE), activated carbon extraction (ACE) and soxhlet extraction (SE) for sediment. The samples were extracted with dichloromethane, cleaned in a silica gel column and the extracts quantified using a Varian 3800 GC-ECD. The percentage recovery test for 2,40DDT, DDE and DDD and 4,40DDT, DDE and DDD in water ranged from 80%–96% and 76%–95% (LLE); 56%–76% and 56%–70% (SPE) and 75%–84% (ACE), respectively; while that recoveries for sediment samples varied from 65%– 95% for 2,40DDT, DDE and DDD and 80%–91% for 4,40DDT, DDE and DDD. The high recoveries exhibited by ACE compared very well with LLE and SE. This was not the case with SPE which exhibited the lowest value of recoveries for both 2,4 and 4,40DDD, DDE and DDT standard samples. The mean concentrations of DDT and metabolites ranged from nd-1.10 lg/L, nd-0.80 lg/L, nd- 1.21 lg/L and 1.92 lg/L for LLE, SPE, ACE and SE, respectively. The total DDT (2,40 and 4,40-DDT) in water and sediment samples ranged from 1.20–3.25 lg/L and 1.82–5.24 lg/L, respectively. The low concentrations of the DDT metabolites obtained in the present study may suggest a recent contamination of the river by DDT.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

No description available.

β-glucan is a major component of the fungal cell wall consisting of (1→3)-β linked glucose polymers with (1→6)-β linked side chains. The published classical isolation procedure of β-glucan from Saccharomyces cerevisiae is expensive and time-consuming. Thus, the aim of this research was to develop an effective procedure for the extraction of glucans. We have developed a new method for glucan extraction that will be cost effective and will maintain the native structure of the glucan. The method that we developed is 80% faster and utilizes 1/3 of the reagents compared to the published classical method. Further, the method developed increases the yield from 2.9 % to 10.3 %. Our new process has a branching frequency of 18.4 down from 197 and a side chain of 5.1 up from 2.5. The data indicate a more preserved native structure of isolated glucans.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-07T14:02:21Z No. of bitstreams: 1 PGCS13MA149.pdf: 530080 bytes, checksum: a5cae9b7f00dc3eaa1bca32791f63b4b (MD5) / Made available in DSpace on 2018-03-07T14:02:21Z (GMT). No. of bitstreams: 1 PGCS13MA149.pdf: 530080 bytes, checksum: a5cae9b7f00dc3eaa1bca32791f63b4b (MD5) Previous issue date: 2013-04-24 / Capes / Brazilian legislation has not yet regulated guiding values of quality references (VRQ) for evaluation of contaminated or polluted. The VRQ are based on evaluations of natural levels of heavy metals in soils without human influence. There are only preventive values (PV), which are the concentrations of metal in the soil limits that do not interfere in its ability to impair their functions and values research (VI). Above them there are potential risks, direct and indirect, to human health and other living organisms. Environmental monitoring of processes of soil contamination requires indicators that serve as a reference for the assessment of impacts. The lifting of the base concentration and propose reference values for heavy metals in soil are critical for identifying contaminated sites and soil monitoring, and to establish criteria for sustainable use and management, preventing risks to the environment and human health. Therefore, it is necessary to establish reference values state, due to the peculiarities of the soil in each region of the country. In this sense, the choice of method of preparation and the opening of soil samples for analysis constitutes a decisive stage of the procedure to diagnose environmental areas polluted or contaminated. This study aimed to compare the analytical methodologies EPA 3051A and 3050B EPA and adjust them in digestions and determinations Nickel and Cd in soil samples reference SRM 2709 San Joaquin certified by the National Institute of Standards and Technology (NIST). Quantification of Ni and Cd were performed in atomic absorption spectrophotometers air-acetylene flame - EAA (CONTRAA 700) and EAA (AAnalyst 200). There was no difference in the levels of Ni and Cd determinations in EAA (ContrAA 700), were below the limit of quantification and EAA (AAnalyst 200) determinations were overestimated. Also determined the natural contents of Ni in soils of Santa Catarina, 102 soil samples more representative of the state. The Ni content varied according to the soil classes and source material, showing the influence of the processes of soil formation in each region / A legislação brasileira ainda não regulamentou valores orientadores de referências de qualidade (VRQ), para avaliação de áreas contaminadas ou poluídas. Os VRQ são baseados nas avaliações dos teores naturais dos metais pesados nos solos, sem a influência antrópica. Existem somente valores de prevenção (VP), que são as concentrações limites de metal no solo que não interferem em sua capacidade de comprometer suas funções e valores de investigação (VI). Acima deles há riscos potenciais, diretos e indiretos, à saúde humana e demais organismos vivos. O monitoramento ambiental de processos de contaminação do solo necessita de indicadores que sirvam como referência para a avaliação dos impactos causados. O levantamento da concentração de base e a proposição de valores de referência para metais pesados no solo são fundamentais para a identificação de áreas contaminadas e monitoramento do solo, e para estabelecer critérios de uso e manejo sustentável, prevenindo riscos ao meio ambiente e à saúde humana. Portanto, é necessário estabelecer-se valores de referência estaduais, devido às peculiaridades do solo de cada região do país. Neste sentido, a escolha do método de preparo e a abertura de amostras de solo para as análises constitui-se numa etapa decisiva do processo que visa o diagnóstico ambiental de áreas poluídas ou contaminadas. O presente trabalho objetivou comparar as metodologias analíticas EPA 3051A e EPA 3050B e ajustá-las nas digestões e determinações de Níquel e Cd em amostras do solo de referência SRM 2709 San Joaquin certificado pelo National Institute of Standards and Technology (NIST). A quantificação de Ni e de Cd foram efetuadas em espectrofotômetros de absorção atômica de chama ar acetileno – EAA ( CONTRAA 700) e EAA (AAnalyst 200). Não houve diferença nos teores de Ni e para o Cd as determinações em EAA (ContrAA 700), ficaram abaixo do limite de quantificação e em EAA (AAnalyst 200) as determinações foram superestimadas. Também se determinaram os teores naturais de Ni em solos de Santa Catarina, utilizando 102 amostras de solos mais representativos do Estado. Os teores de Ni variaram de acordo com as classes de solo e material de origem, demostrando a influência dos processos de formação do solo de cada região

No description available.

<p dir="ltr">We propose a new way to improve the efficiency of the quality review process using the image-based learning approach. This is achievable because we have learned that there is a correlation between the sensor’s surface texture and its performance. Also, the fabrication parameters directly affect the thickness of the ion-selective membrane (ISM) of the nitrate sensors and therefore affect the texture on the sensor’s surface. Given that information, we can quickly predict the sensor performance and make rapid modifications to the fabrication parameters using our image-based prediction model.</p>

Dagens intensiva användning av plast genererar mikroplaster som på olika sätt sprids ut i vår omgivning och medför risker för naturliga system världen över. Dessa mikroplaster härrör från bland annat hushåll, industrier och deponier, och färdas ofta med avloppsvattten och i viss utsträckning dagvatten till reningsverk. Där renas vattnet och en stor del av mikroplasterna ansamlas i det slam som bildas i samband med vattenreningen. Slammet består till stora delar av organiskt material och näring, och betraktas ofta som en resurssnarare än avfall. Cirka 50 % av det slam som bildas i europeiska reningsverk används som gödningsmedel inom jordbruk. Det innebär att slamgivor potentiellt är källor för spridning av stora mängder mikroplast. Idag är kunskapen om mikroplaster i slam relativt liten och en standardiserad metod för extrahering av mikroplaster ur slam saknas, vilket begränsar möjligheten att se problemets magnitud. Detta examensarbete strävar efter att bidra till utformandet av en sådan metod, och undersöker förekomsten av mikroplaster i slam från Ekeby reningsverk i Eskilstuna och Käppalaverket på Lidingö utanför Stockholm med hjälp av två olika metoder. De båda metoderna kombinerar oxidativ nedbrytning med hjälp av fenton-reagens och densitetseparering för att skilja mikroplaster från organiskt och inorganiskt material. Skillnaden mellan de olika metoderna är att den ena innehåller ett oxiderande moment och den andra två. Rapporten behandlar huruvida det extra oxiderande momentet har någon betydande skillnad för utvinningen av mikroplaster ur slam, samt om förekomsten av mikroplasterskiljer sig åt mellan slam från de två olika reningsverken. Resultaten visar att det finns en skillnad mellan de två extraheringsmetoderna samt viss skillnad mellan förekomsten av mikroplaster i de olika slammen. I rapporten diskuteras huruvida skillnaden mellan resultaten av de två olika metoderna beror på det extra oxiderande momentet, eller andra tillkommande effekter. Vad gäller mikroplasters förekomst i slam från de olika reningsverken fastslås att de skiljer sig åt kvantitativt, och i viss mån även kvalitativt.

ii SUMMARY This master thesis deals with selectivity assessment of an arsenic sequential extraction procedure for evaluating mobility in mine wastes. A modified sequential extraction procedure was designed on the basis of preliminary tests of extraction efficiency and selectivity for the synthetic As mineral phases (scorodite, amorphous iron arsenate, schwertmannite, goethite, jarosite) and five natural samples (Kaňk, Dlouhá Ves, Giftkies, Roudný) that were previously characterized for As concentration and speciation. The modified sequential extraction has five steps. The first leaching step was performed in nitrogen-purged deionized H2O for 10 hours; next step involved 0.01M NH4H2PO4 leaching for 16 hours. Phases in the third step were dissolved with 0.2M Tamm`s reagent in darkness for 2 hours. The fourth step was represented by 0.2M of Tamm`s reagent heated in water bath at 80řC for 4 hours. Strong acid solutions HCl/KClO3/HNO3 were used to leach sulphide phases in the last step. The testing of the sequential extraction procedure using model mixtures showed a good discrimination of several fractions: adsorbed arsenic, arsenic associated with poorly crystalline oxyhydroxide, hydroxosulfate and arsenate phases (amorphous iron arsenate, schwertmannite, ferrihydrite), arsenic associated with crystalline...