Syftet med studien är att undersöka hur resultaten i läsförståelse från DLS-tester hos en grupp elever har utvecklats ur ett tidsperspektiv och jämföra detta med den enskilde individens perspektiv på sin läsförståelse. Med en kvalitativ metod har jag gjort en jämförande undersökning i en grundskoleklass. Först har jag genomfört en studie över tid på resultaten av DLS-tester i år 4, 6 och 8. Därefter har jag genomfört en intervju med en urvalsgrupp på fyra elever. Elevernas resultat från DLS- testen tyder i de flesta fall inte på en positiv utveckling av elevernas läsförståelse från år 4-8. Av intervjuerna framgår det att eleverna inte har upplevt något märkbart aktivt arbete i skolan som skulle kunna öka deras läsförståelse. Dessutom kan man utläsa av elevernas svar att testerna ej varit en synlig del i utvecklingen av deras läsförståelse. Trots detta upplever alla fyra eleverna att deras läsförståelse har utvecklats under skoltiden.

No presente trabalho foi investigado o efeito do oligonucleotídeo-modelo 5-AAAAAAAAAA-3(ODN) sobre a estabilidade e estrutura de vesículas catiônicas de brometo de dioctadecildimetilamônio (DODAB), extrusadas através filtros de 100 nm, em dispersão aquosa, com as técnicas de espalhamento de luz dinâmico (DLS), medidas de potencial de superfície (potencial zeta), calorimetria diferencial de varredura (DSC), espalhamento de raios-X a baixos ângulos (SAXS), espectroscopias de absorção óptica e de fluorescência do estado estacionário da sonda Laurdan incorporada a vesículas de DODAB-ODN. Este fluoróforo monitora a polaridade e estrutura da superfície da membrana de DODAB. Variando a concentração de ODN, três diferentes regimes foram observados. Para baixas concentrações de ODN, ([ODN]/[DODAB]) 0.025 mM, a dispersão é estável, límpida, apesar do diâmetro médio das vesículas aumentar, um aumento de turbidez ser observado por medidas de Absorbância, e o SAXS já acusar a presença de algumas poucas multilamelas. As vesículas mistas apresentam potencial de superfície positivo, semelhante ao potencial medido para vesículas de puro DODAB. A calorimetria mostra a coexistência de regiões da bicamada de puro DODAB, e regiões mistas, com DODAB-ODN, sendo estas últimas mais estáveis, apresentando maior temperatura de transição gel-fluido. A forma e posição da banda de fluorescência do Laurdan incorporado às vesículas não são alteradas pela presença do oligonucleotídeo, indicando pouca variação na polaridade e estrutura da superfície da membrana mista monitorada pela sonda. Um segundo regime é observado para ([ODN]/[DODAB]) 0.05 mM, onde não é mais observado por calorimetria a presença significativa de domínios de puro DODAB, e a dispersão mostra-se instável, turva, com agregação/fusão das vesículas. Finalmente, o terceiro regime, para altas concentrações de ODN, ([ODN]/[DODAB]) 0.075 mM, onde é observado um potencial de superfície negativo, portanto, com predominância da carga do oligonucleotídeo, e a dispersão volta a ser estável, apresentando baixa turbidez. Neste regime, a calorimetria indica uma grande estabilidade da fase gel, medidas de SAXS mostram a formação de estruturas multilamelares, porém DLS indica a presença de vesículas pequenas, com dimensões às observadas para DODAB puro. Neste regime, a sonda Laurdan monitora variações na superfície da membrana, possivelmente indicando a diminuição da quantidade de moléculas de água na superfície e/ou um enrijecimento da bicamada. Os estudos aqui apresentados fazem parte de um amplo esforço para entender as características estruturais de agregados lipídio-material genético, com o objetivo de seu uso futuro em terapias gênicas. / In the present work the effect of 5\'-AAAAAAAAAA-3 \'oligonucleotide model (ODN) was investigated on the stability and structure of dioctadecyldimethylammonium bromide (DODAB) cationic vesicles, extruded through 100 nm filters in aqueous dispersion, with dynamic scattering techniques (DLS), surface potential measurements (zeta potential), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), optical absorption spectrometry and stationary-state fluorescence spectroscopy of Laurdan incorporated into DODAB-ODN vesicles. This fluorophore monitors the polarity and surface structure of the DODAB membrane. Varying the ODN concentration, three different behaviors were observed. For low concentrations of ODN, ([ODN] / [DODAB]) 0.025 mM, the dispersion is stable, clear, although the mean diameter of the vesicles increases, an increase in turbidity is observed by Absorbance measurements, and SAXS already shows the presence of a few multilamellar structure. The mixed vesicles present positive surface potential, similar to the potential measured for pure DODAB vesicles. Calorimetry shows the coexistence of regions of the pure DODAB bilayer, and mixed regions, with DODAB-ODN, the latter being more stable, presenting a higher gel-fluid transition temperature. The shape and position of the Laurdan fluorescence band incorporated into the vesicles are not altered by the presence of the oligonucleotide, indicating minor variation in the polarity and surface structure of the mixed membrane monitored by the probe. A second behavior is observed for ([ODN] / [DODAB]) 0.05 mM, where the presence of pure DODAB domains is no longer detected by calorimetry, and the dispersion is unstable, cloudy, displaying vesicle aggregation/fusion. Finally, the third behavior is detected at high concentrations of ODN, ([ODN] / [DODAB]) 0.075 mM, where a negative surface potential is observed, therefore, with predominance of the charge of the oligonucleotide, and the dispersion is stable, exibiting low turbidity. In this regime, the calorimetry indicates a great stability of the gel phase, SAXS measurements show the formation of multilamellar structures, however DLS indicates the presence of small vesicles, with dimensions to those observed for pure DODAB. In this region, the Laurdan probe monitors variations at the surface of the membrane, possibly indicating the decrease in the amount of water molecules on the surface and/or a stiffening of the bilayer. The studies presented here are part of a broad effort to understand the structural characteristics of \"lipid-genetic material\", aggregates, with the aim of their future use in gene therapies.

No presente trabalho foi investigado o efeito do oligonucleotídeo-modelo 5-AAAAAAAAAA-3(ODN) sobre a estabilidade e estrutura de vesículas catiônicas de brometo de dioctadecildimetilamônio (DODAB), extrusadas através filtros de 100 nm, em dispersão aquosa, com as técnicas de espalhamento de luz dinâmico (DLS), medidas de potencial de superfície (potencial zeta), calorimetria diferencial de varredura (DSC), espalhamento de raios-X a baixos ângulos (SAXS), espectroscopias de absorção óptica e de fluorescência do estado estacionário da sonda Laurdan incorporada a vesículas de DODAB-ODN. Este fluoróforo monitora a polaridade e estrutura da superfície da membrana de DODAB. Variando a concentração de ODN, três diferentes regimes foram observados. Para baixas concentrações de ODN, ([ODN]/[DODAB]) 0.025 mM, a dispersão é estável, límpida, apesar do diâmetro médio das vesículas aumentar, um aumento de turbidez ser observado por medidas de Absorbância, e o SAXS já acusar a presença de algumas poucas multilamelas. As vesículas mistas apresentam potencial de superfície positivo, semelhante ao potencial medido para vesículas de puro DODAB. A calorimetria mostra a coexistência de regiões da bicamada de puro DODAB, e regiões mistas, com DODAB-ODN, sendo estas últimas mais estáveis, apresentando maior temperatura de transição gel-fluido. A forma e posição da banda de fluorescência do Laurdan incorporado às vesículas não são alteradas pela presença do oligonucleotídeo, indicando pouca variação na polaridade e estrutura da superfície da membrana mista monitorada pela sonda. Um segundo regime é observado para ([ODN]/[DODAB]) 0.05 mM, onde não é mais observado por calorimetria a presença significativa de domínios de puro DODAB, e a dispersão mostra-se instável, turva, com agregação/fusão das vesículas. Finalmente, o terceiro regime, para altas concentrações de ODN, ([ODN]/[DODAB]) 0.075 mM, onde é observado um potencial de superfície negativo, portanto, com predominância da carga do oligonucleotídeo, e a dispersão volta a ser estável, apresentando baixa turbidez. Neste regime, a calorimetria indica uma grande estabilidade da fase gel, medidas de SAXS mostram a formação de estruturas multilamelares, porém DLS indica a presença de vesículas pequenas, com dimensões às observadas para DODAB puro. Neste regime, a sonda Laurdan monitora variações na superfície da membrana, possivelmente indicando a diminuição da quantidade de moléculas de água na superfície e/ou um enrijecimento da bicamada. Os estudos aqui apresentados fazem parte de um amplo esforço para entender as características estruturais de agregados lipídio-material genético, com o objetivo de seu uso futuro em terapias gênicas. / In the present work the effect of 5\'-AAAAAAAAAA-3 \'oligonucleotide model (ODN) was investigated on the stability and structure of dioctadecyldimethylammonium bromide (DODAB) cationic vesicles, extruded through 100 nm filters in aqueous dispersion, with dynamic scattering techniques (DLS), surface potential measurements (zeta potential), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), optical absorption spectrometry and stationary-state fluorescence spectroscopy of Laurdan incorporated into DODAB-ODN vesicles. This fluorophore monitors the polarity and surface structure of the DODAB membrane. Varying the ODN concentration, three different behaviors were observed. For low concentrations of ODN, ([ODN] / [DODAB]) 0.025 mM, the dispersion is stable, clear, although the mean diameter of the vesicles increases, an increase in turbidity is observed by Absorbance measurements, and SAXS already shows the presence of a few multilamellar structure. The mixed vesicles present positive surface potential, similar to the potential measured for pure DODAB vesicles. Calorimetry shows the coexistence of regions of the pure DODAB bilayer, and mixed regions, with DODAB-ODN, the latter being more stable, presenting a higher gel-fluid transition temperature. The shape and position of the Laurdan fluorescence band incorporated into the vesicles are not altered by the presence of the oligonucleotide, indicating minor variation in the polarity and surface structure of the mixed membrane monitored by the probe. A second behavior is observed for ([ODN] / [DODAB]) 0.05 mM, where the presence of pure DODAB domains is no longer detected by calorimetry, and the dispersion is unstable, cloudy, displaying vesicle aggregation/fusion. Finally, the third behavior is detected at high concentrations of ODN, ([ODN] / [DODAB]) 0.075 mM, where a negative surface potential is observed, therefore, with predominance of the charge of the oligonucleotide, and the dispersion is stable, exibiting low turbidity. In this regime, the calorimetry indicates a great stability of the gel phase, SAXS measurements show the formation of multilamellar structures, however DLS indicates the presence of small vesicles, with dimensions to those observed for pure DODAB. In this region, the Laurdan probe monitors variations at the surface of the membrane, possibly indicating the decrease in the amount of water molecules on the surface and/or a stiffening of the bilayer. The studies presented here are part of a broad effort to understand the structural characteristics of \"lipid-genetic material\", aggregates, with the aim of their future use in gene therapies.

De nos jours, les nanomatériaux sont utilisés dans de très nombreux domaines allant de l’agroalimentaire à la santé en passant par l’industrie automobile et le textile. Dans ce contexte, de nombreuses disciplines comme la métrologie et la nanotoxicologie se sont fortement développées. Dans les milieux biologiques, les protéines interagissent avec les nanoparticules pour former une couronne de protéines. Cette couronne de protéines joue un rôle important dans les interactions des nanoparticules avec leur environnement. Comprendre et caractériser les interactions des nanoparticules avec les protéines permettraient d’améliorer l’utilisation des nanoparticules dans différents domaines, notamment dans celui de la santé. Nous avons d’abord mis au point une méthode de purification des nanoparticules permettant de préserver la structure et la composition de la couronne protéique (Asymmetric flow field-flow fractionation, AF4). Nous avons ensuite caractérisé la couronne protéique associée à ces nanoparticules par plusieurs méthodes telles que la sédimentation centrifuge différentielle, la microscopie électronique, des méthodes basées sur la diffusion de la lumière (diffusion dynamique de la lumière (DLS) et la résonance plasmonique de surface localisée ou non), le dichroïsme circulaire classique et le Synchrotron Radiation Circular Dichroism (SRCD, Diamond, UK). Nous avons montré qu’une couronne d’albumine sérique humaine provoque une augmentation du diamètre hydrodynamique des nanoparticules d’or de 14 à 25,3 nm et une diminution de la densité d’un facteur 2. Ceci nous a permis de calculer que 19 molécules d’albumine en moyenne interagissent avec une nanoparticule. Les spectres de dichroïsme circulaire ont permis d’estimer que l’albumine conserve environ 70% de ses structures hélicoïdales lorsqu’elle est complexée avec les nanoparticules. Nous avons estimé l’affinité avec laquelle les nanoparticules d’or interagissent qui est d’environ 351 nM pour l’albumine et 513 nM pour la transthyrétine qui est riche en brins béta. Nous avons également optimisé une méthode de couplage de l’AF4 à un appareil de mesure de la diffusion dynamique de la lumière (DLS) pour améliorer la précision de la mesure du diamètre hydrodynamique des nanoparticules. Cette méthode précise et flexible permettra de caractériser de nombreuses modifications de surface des nanoparticules comme l’ajout de polyéthylène glycol, utilisées pour la conception de nano-médicaments / Nowadays, nanomaterials are used in numerous areas ranging from food to health through cars and textile engineering. In this context, many disciplines such as metrology and nanotoxicology, have been developed. In biological fluids, proteins interact with nanoparticles to form the protein corona, which plays an important role in mediating the interactions of the nanoparticles with their environment. Understanding and characterizing the interactions of nanoparticles with proteins and the corona structure would improve their use in various fields and particularly in the health sector. We have first developed a method based on Asymmetric Flow Field Flow Fractionation (AF4) for purifying gold nanoparticles preserving the structure and composition of the protein corona. Then we have characterized the protein corona associated to these nanoparticles by differential centrifugal sedimentation, electron microscopy, light scattering (dynamic light scattering, DLS), surface plasmon resonance (SPR) and localized SPR and by circular dichroism (classical CD and Synchrotron Radiation Circular Dichroism, SRCD, Diamond, UK). We have shown that human serum albumin corona increased the hydrodynamic diameter of the gold nanoparticles from 14 to 25.3 nm and decreases their density by a factor of 2. This enabled us to calculate that 19 albumin molecules on average interact with a nanoparticle. We have estimated by circular dichroism that albumin maintains about 70% of its helical structures when complexed with nanoparticles. The affinity between gold nanoparticles and proteins, is about 351 nM for albumin and 513 nM for transthyretin, which are enriched in helices and beta strands respectively. We have also optimized a coupling method between the AF4 system and the dynamic light scattering apparatus to improve the measurement accuracy of the hydrodynamic diameter of the nanoparticles. This accurate and flexible method will be helpful to characterize many surface modifications of the nanoparticles such as the addition of polyethylene glycol used for the design of nanodrugs

The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of NP4 to total surfactant (r), the water to surfactant molar ratio (ω), temperature, salt concentration, and polar phase. The basis of our investigation was nonylphenol polyethoxylates - NP4 and NP7. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model reverse micelle size as a function of ω, [NP], and r. The model has demonstrated the capability of predicting the mean diameter of micelles from 4 to 13 nm with a precision of ± 2 nm as measured by DLS. This quantitative correlation between the size of reverse micelles and the synthetic variables provides the foundation for choosing experimental conditions to control reverse micelle size.

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2017-05-09T14:28:22Z No. of bitstreams: 1 2016 - Leonardo Santos de Barros.pdf: 6766023 bytes, checksum: 16ce8cf6e87d3cfab0a3d73fc9a6e46c (MD5) / Made available in DSpace on 2017-05-09T14:28:22Z (GMT). No. of bitstreams: 1 2016 - Leonardo Santos de Barros.pdf: 6766023 bytes, checksum: 16ce8cf6e87d3cfab0a3d73fc9a6e46c (MD5) Previous issue date: 2016-11-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The photochemical reactivity of chalcone (CH) nanocrystals and its fluorinated derivatives (CH4F, CH23F, CH25F, CH26F, CH34F, CH35F, PFCB and the DFC) in a suspension of aqueous CTAB (0.04 mM) was studied by ultraviolet spectroscopy (UV), hydrogen nuclear magnetic resonance (H1NMR) and dynamic light scattering (DLS). The suspension of chalcone nanocrystals was prepared by the reprecipitation method in an aqueous solution of CTAB. The ultraviolet spectrum for the chalcone nanocrystals prior to irradiation showed hypochromic and bathochromic effects when compared to the methanolic solution. The DLS spectrum for CH CH23F, CH25F, CH26F and PFCB nanocrystals in aqueous CTAB showed a polydispersed system containing three different particle sizes, whereas CH34F, CH35F and DFC nanocrystals showed a clear monodispersivity. After irradiation, the DLS spectrum for these nanocrystals did not show significant changes, however for the monodispersed chalcones a shift towards larger particle sizes was observed. After irradiation the UV spectrum for the chalcone nanocrystals indicated a hypochromic effect on the longer wavelength band, which may be related to the consumption of their E-isomer. The kinetic monitoring of the E-isomer consumption for the chalcones CH, CH4F, CH23F, CH25F, CH26F CH34F, CH35F, PFCB and DFC as a function of irradiation time indicated that after a certain time the reaction reaches a steady state, with no more changes on their absorbance. The H1NMR spectrum for the irradiation product of CH4F and CH23F showed the formation of a mixture of ?-, ??-, and ?-truxillic dimers. On the other hand, irradiation of CH25F and CH26F derivatives led to the formation of the ?-truxinic dimer. Photolysis of CH34F and CH35F nanocrystals showed the conversion of the reactant to a cyclobutane through a stereospecific reaction. For CH35F only the ?-truxillic dimer has been formed, in nearly 100% conversion. However, for nanocrystals of the chalcone CH34F the Z-isomer is formed together with the ?-truxillic dimer CH34F, which may be related to a chalcone fraction that was solubilized in the CTAB containing aqueous phase. Irradiation of DFC nanocrystals occurred at a conversion of almost 100% to the cycloaddition product, the ?-truxillic dimer. For chalcone (CH) a high yield formation of the Z-chalcone isomer and dimers that are not formed from its E-isomer was observed, while PFCB appeared as a stable molecule during the irradiation process, and the presence of the five fluorine atoms on the benzyl ring can account for its stability / A reatividade fotoqu?mica de nanocristais de chalcona (CH) e seus derivados fluorados (CH4F, CH23F, CH25F, CH26F, CH34F, CH35F, PFCB e DFC) foi estudada por espectroscopia de ultravioleta (UV), Resson?ncia magn?tica nuclear de hidrog?nio (RMN1H) e Espalhamento de luz din?mico (DLS). A suspens?o dos nanocristais das chalconas foi preparada pelo m?todo de reprecipita??o em uma solu??o aquosa de CTAB. Os espectros no ultravioleta para a suspens?o dos nanocristais das chalconas antes da irradia??o mostraram um efeito hipocr?mico e batocr?mico em rela??o ? solu??o metan?lica. Os espectros de DLS para os nanocristais da suspens?o das chalconas em solu??o aquosa de CTAB se apresentaram como um sistema polidisperso apresentando 3 tamanhos de part?culas para CH, CH23F, CH25F, CH26F, PFCB e monodisperso para CH34F, CH35F e DFC. Ap?s a irradia??o n?o se observou mudan?as significativas na estrutura dos espectros de DLS para os nanocristais, ocorrendo um deslocamento para tamanhos de part?culas maiores nas chalconas monodispersas. O espectro de UV para a suspens?o dos nanocristais das chalconas ap?s a irradia??o indicou um efeito hipocr?mico da banda de maior absor??o, o que pode estar relacionado ao consumo dos compostos de configura??o E. O acompanhamento cin?tico do consumo do is?mero E das chalconas CH, CH4F, CH23F, CH25F, CH26F CH34F, CH35F, PFCB e DFC contra tempo de irradia??o de uma suspens?o dos nanocristais destas chalconas em solu??o aquosa de CTAB (0,04 mM) indicou que a partir de um determinado tempo a rea??o atinge um estado estacion?rio, n?o apresentando mais mudan?as em sua absorb?ncia. Os espectros de RMN1H para o produto da irradia??o dos nanocristais das chalconas contendo fl?or na posi??o 4 (CH4F) e nas posi??es 2 e 3 (CH23F) mostraram a forma??o de uma mistura de d?meros ?????? e ?-trux?licos. A irradia??o dos derivados CH25F e CH26F levou ? forma??o do d?mero do tipo ?-trux?nico. Para os derivados CH34F e CH35F a convers?o dos reagentes ao fotociclobutano foi feita em uma forma estereoespec?fica, tendo sido formado somente o d?mero ?-trux?lico, com uma convers?o de quase 100% para o CH35F. No entanto, para os nanocristais da chalcona CH34F o is?mero Z-CH34F foi formado juntamente com o d?mero ?-trux?lico, o que pode estar relacionado a fra??es da chalcona que ficaram solubilizadas na fase aquosa contendo CTAB e n?o formaram suspens?o de nanocristais. A irradia??o dos nanocristais da chalcona DFC ocorreu com uma convers?o de quase 100% ao produto de fotocicloadi??o, sendo o d?mero formado o do tipo ?-trux?lico. Para chalcona (CH) observou-se um elevado rendimento de forma??o do is?mero Z-chalcona e de d?meros que n?o s?o provenientes do is?mero E, enquanto que PFCB apresentou-se como uma mol?cula est?vel durante o processo de irradia??o, com a presen?a dos cinco ?tomos de fl?or no anel benz?lico podendo ser respons?vel pela sua estabilidade

The ability of surfactants to form micelles and solubilise hydrophobic substances in aqueous environments has been widely exploited in formulation science. In spite of extensive studies over the past few decades by both experimental and theoretical methods, however, it remains difficult to predict key micellar parameters such as their size, shape and nanostructure which is essential for their successful implementation in the solubilisation of active ingredients. This is partly due to the vast number of surfactants commercially available but, in addition, the fragmentation of the field of surfactant science, over recent years, has made it more difficult to identify general trends and properties of surfactant systems. A further challenge is in characterising systems of heavily mixed surfactants since our knowledge on pure surfactant systems may not allow us to predict the behaviour of these systems. The broad aim of this thesis was to contribute to these aspects of surfactant science. The first part of the thesis reports a systematic study of the surfactant structure-micellar structure relationship of pure alkyl ethoxylate (CmEn) surfactants. This was done by independently varying the lengths of the alkyl chain and ethoxylate group and measuring the micellar structural properties. The next part of the thesis reports the effects of solubilisation of two model pesticides, Cyprodinil and Diuron, on the size, shape and internal structure of these surfactant micelles. These pesticides were chosen because they were structurally representative of different features of those widely used in agrochemicals. The final part of the thesis reports the work on binary surfactant mixtures that rationalise the general structural features of mixed micelles and their impact on pesticide solubilisation. Various experimental techniques were used including small angle neutron scattering (SANS), nuclear magnetic resonance (NMR), nuclear Overhauser effect spectroscopy (NOESY NMR), dynamic light scattering (DLS) and UV spectroscopy. The key findings of the thesis were that the micellar core volumes could be predicted with reasonable accuracy using the hydrophilic-lipophilic balance (HLB) of the surfactants in pure micelles. NOESY results revealed protrusions of the terminal methylene groups into the ethoxylate shell, thus providing evidence for the theoretically predicted phenomenon referred to as the-shell interface. SANS revealed that solubilisation of both pesticides caused micellar growth, with the long axial lengths of the micelles growing much longer. These structural changes were associated with the dehydration of the ethoxylate shells. Although a partitioning experiment predicted that the pesticides would be solubilised in the hydrated ethoxylate micellar shell, NOESY measurements revealed that the solubilisation occurred predominantly in the micellar cores. The discrepancy was caused by alkyl chain-ethoxylate mixing leading to the formation of dehydrated palisade regions that entrapped the pesticides towards the cores. The results from the binary mixed micelles showed some signs of synergistic behaviour but no enhancement of pesticide solubilisation.

A variety of approaches were conducted to obtain a comprehensive understanding of the adsorption of Natural Organic Matter (NOM) isolates on metal oxides (MeO). Adsorption experiments with a series of small molecular weight (MW), oxygenated, aromatic organic acids were performed with Aluminum oxide (Al2O3), Titanium oxide (TiO2), and Zirconium oxide (ZrO2) surface. The experiments were conducted in batch mode at pH 4.2 and 7.6. The adsorption of simple organic acids was described by Langmuir model, and exhibited strong dependence on the relative abundance of carboxyl group, aliphaticity/aromaticity, length of alkyl chain, and the presence of hydroxyl group. The adsorption of the model compounds was high at low pH and decreased with increasing the pH. Isolated NOM fraction of strong humic character, i.e., hydrophobic (HPO) (high in MW, aromaticity, and acidity), i.e., Suwannee River fulvic acid (SRW HPO), showed strong adsorption on all MeO. However, fractions with similar acidic character, and lower MW exerted weak adsorption. NOM fraction that incorporated polysaccharides and proteins like structures (i.e., biopolymers) was not significantly adsorbed compared to HPO fractions. Interestingly, biopolymer adsorption on Heated Aluminum oxide particles (HAOP) was higher than that on Al2O3, TiO2, and ZrO2. These different adsorption profiles were related to their physicochemical characteristics of NOM and MeO, and thus, showed different interacting mechanisms and were studied by Atomic Force Microscopy (AFM). Hydrogen bonding was suggested as the main mechanism between NOM of strong hydrophilic character (i.e., biopolymers) and Al2O3, TiO2 and ZrO2 coated wafers. The strength of the hydrogen bonding was influenced by the hydrophilicity degree of MeO surface, ionic strength, and cation type. NOM fractions with strong humic character showed repulsive forces that are electrostatic in nature with MeO of high negative charge density. Hydrogen bonding and ligand exchange mechanisms are proposed to control the adsorption mechanism at high ionic strength with less negatively-charged MeO surface. Strong interactions forces was recorded between NOM molecules with different properties, more specifically with high MW humic and non humic fractions. These forces are controlled by cation type, and NOM chemical structure.

Denna uppsats utforskar ett par lärares och beslutsfattares tankar kring läsförståelse samt tankar kring ett specifikt läsförståelsetest DLS, men även tankar kring befrämjande arbete med läsförståelsekompetens i en specifik kommun. Undersökningen genomfördes 2008-2009 i tre forskningsfaser 1) enskild intervju 2) enkätstudie och 3) gruppintervju. Jag har använt mig av metodtriangulering. Undersökningen visar generellt sett att de flesta 6-9 lärarna i svenska upplever DLS som ett bra mätredskap och att resultaten från DLS överensstämmer med deras uppfattning om elevernas läsförståelse. Majoriteten av lärarna upplever att läsförståelsekompetensensjunker och att de delvis arbetar mer med läsning efter de senaste årens DLS resultat. Det är vanligt att de flesta lärarna kompletterar sin undervisning med bilder och att texterna i läroböckerna upplevs som kompakta och svårbegripliga.

No description available.