Investigation of Stimuli-Responsive Polymer Nanocomposites for Dye Treatment in Aqueous Solution

Currently, environmental pollution associated with dyes has become an issue of global concern that is gaining significant attention. Developing inexpensive nanocomposites via combination of functional properties of dissimilar materials is of increasing interest for dye treatment in aqueous solution. Chitosan is a natural, low-cost, biocompatible and biodegradable polymer that is widely researched and applied in advanced water treatment. π-conjugated polyaniline is a notable polymer for adsorption purposes due to the relatively low cost of the monomer precursor, environmental stability, ease of doping/de-doping chemistry and its relatively high nitrogen content. Among conductive polymers polyaniline is one of the most highly studied. Unfortunately, there are some technical limitations associated with each respective polymer; chitosan and polyaniline. Therefore, the application chitosan and PANI in adsorption and catalytic treatment processes of dyes is somewhat limited since single component polymer systems possess limited adsorption sites and low surface area without further synthetic modification. This thesis investigates various approaches for dye removal from aqueous solution via development of chitosan and polyaniline-based stimuli-responsive nanocomposite materials. These approaches continue to be of great interest since they combine functional properties of dissimilar materials to design multifunctional nanocomposites with enhanced properties. The major aim of this thesis is the development of nanocomposite materials for treatment of dye pollutants from aqueous solution. In the first section of this thesis, to overcome the weaknesses of chitosan, it was modified to develop pH-responsive polymer brush nano adsorbents for controlled adsorption of methylene blue. By grafting poly anion functional groups to the chitosan backbone, and integrating such a system onto iron oxide nanocrystals, significant enhancement was observed for methylene blue adsorption. This effect was achieved through electrostatic interactions and osmotic pressure, where the regeneration of the nanocomposite was facilitated with stimuli-responsiveness and magnetic separation. In the second section redox-responsive catalyst systems were developed and utilized towards reduction of 4-nitrophenol with sodium borohydride. Single component precursor (Ag nanoparticles, chitosan and polyaniline) materials are observed to display poor catalytic reduction with 4-nitrophenol reduction. By interfacing a stimuli-responsive polymer with silver nanoparticles, greater catalytic activity was demonstrated for the enhanced reduction of 4-nitrophenol with respect to the single component precursors. Nanocomposites of this type offered a new and efficient approach for conversion of 4-nitrophenol to 4-aminophenol. Following on the research of methylene blue adsorption, polyaniline/chitosan magnetic nanocomposites were synthesized and used for removal of methylene blue via adsorption in aqueous media. Molecular selective adsorption of methylene blue and methyl orange was measured to bring insight into the adsorption properties of polyaniline nanostructures. In addition, the interaction of polyaniline with NaCl was investigated as a path to further explore dye adsorption onto a polymer in a de-doped state. During this project, it was discovered that polyaniline interacts with salt, which resulted in weakening of the intramolecular hydrogen bonding as confirmed by dynamic light scattering and Raman spectroscopy. The salt-responsive behavior of nanocomposites and their preference to adsorption of a cationic dye over an anionic dye proved that methylene blue likely associates with de-doped polyaniline in a similar fashion as Na+ ions do via cation-dipole interactions. To better understand the observed experimental results of salt and dye interaction with polyaniline, nitrogen containing self-healing materials were encapsulated inside polyaniline macroparticles (size of ca. 500 nm) and their release upon exposure to salt was monitored. Therefore, a versatile-activation type of delivery systems was developed. The kinetics of release further unraveled the details of methylene blue adsorption and disintegration of polyaniline upon interaction with salt. The results demonstrated that such interactions and disintegration of polyaniline is the result of a combination of various factors (such as osmotic pressure within polymer shell, polymer permeability, polymer flexibility and dynamic motion) that work in a cooperative fashion. In particular, the role of anion hydration according to the Hofmeister series plays a key role on stabilizing the doped polyaniline-M+ complex

Information and experience: Audiovisual observations of reading activities in Swedish comprehensive school classrooms 1967–1969

This study investigates reading activities in Swedish primary school classrooms during the late 1960s. Sound and video recordings of 223 Swedish lessons held between 1967 and 1969 are used to analyse the activity of reading as taught and performed. The results indicate that the practice of informational reading, often based on finding predetermined, explicit "facts" in textbooks through individual, silent reading, was common. The practice of experiential reading, based on fiction, imagination and the joy of reading, was not only less common, but also often compromised by instrumental concerns. In the national curriculum of the time, the practice of informational reading was related to study skills and was intended to prepare all pupils for higher-level education. While often appearing over-proportioned, superficial and fragmented, these reading practices were still intentional objects of learning and teaching, and were grounded in the democratic and egalitarian ideals of Swedish post-war educational policy

Reading as dialogical document work: possibilities for Library and Information Science

Purpose – The purpose of this paper is to introduce a dialogically based theory of documentary practices and document work as a promising framework for studying activities that are often conceptualised as information behaviour or information practices within Library and Information Science (LIS). Design/methodology/approach – An empirical example – a lesson on how to read railway timetables – is presented. The lesson stems from a research project including 223 Swedish lessons recorded in Swedish primary schools 1967-1969. It is argued that this lesson, as many empirical situations within LIS research, can fruitfully be regarded as documentary practices which include document work such as reading, rather than instances of information behaviour. Findings – It is found that the theoretical perspective of dialogism could contribute to the theory development within LIS, and function as a bridge between different subfields such as reading studies and documentary practices. Research limitations/implications – The framework is yet to be applied on a larger scale. This would require a willingness to go beyond the entrenched idea of information as the core theoretical concept and empirical object of study within LIS. Social implications – The theoretical framework offers a view of the relations between individuals, documents, and social contexts, through which it is possible to explore the social significance of core LIS concerns such as reading, literacy, and document work. Originality/value – The theoretical framework offers an alternative to the monologist, information-based theories and models of people’s behaviours and practices prevalent in LIS

Aesthetic reading as a problem in mid-20th century Swedish educational policy

This study aims to identify and analyse how aesthetic reading was problematised in Swedish educational policy 1940-1962, in order to create a better understanding of the politics of reading in an era that has been of great importance for how reading is understood in contemporary Sweden. The empirical material consists of reports from three school commissions, laying the foundation for the new compulsory and comprehensive school that was introduced in 1962. The reports have been analysed using a discursive methodological framework, focussing on problematisations of aesthetic reading. The main problem that aesthetic reading was meant to solve, according to the analysis, was a lack of aesthetic taste. There is a shift in emphasis during the period from problematisations of what to read towards problematisations of how to read. Thus, the solution to the problem of aesthetic reading during the period transformed from a governing of taste to a governing of skills. Educational and cultural policy shares the problematisation of aesthetic upbringing, made possible by its roots in modernist ideas of general character formation and the ideals of free public education. We argue that research on the politics of reading in Sweden can be reinvigorated by exploring the governance of cultural practices emanating from policy fields other than explicit cultural policy

Management of a crown-root fracture in central incisors with 180° rotation: A case report

ABSTRACT: The crown-root fracture is a common tooth injury which compromises the biological width and need proper endodontic and prosthodontic treatment to achieve acceptable clinical outcome. This case report describes clinical management of crown-root fracture in maxillary central incisors which was successfully treated by forceps eruption with 180˚ rotation to restore the biological width. The patient was followed-up for 18 months. Clinical and radiographic evaluation showed acceptable results, the replanted teeth have normal function and no obvious inflammatory root resorption was seen on radiographic examination

Diffuse Large B-cell Lymphoma during Pregnancy

Introduction:Non-Hodgkin Lymphoma (NHL) during pregnancy are very uncommon, and primary symptoms of NHL are similar to pregnancy physiologic changes.Case presentation:We report a case of NHL during pregnancy that didn’t have any peripheral lymphadenopathy, with mediastinal involvement. Chemotherapy began during pregnancy and after delivery treatment continued with chemotherapy and radiotherapy, and mother and baby were both healthy.Conclusion: Early diagnosis of NHL cause to better prognosis of disease andmaking a chance for mother to make a decision about continue pregnancy or not and about her treatments