16 resultados para Continued formation of teachers
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Selostus: Kylvötiheyden ja kasvunsääteiden vaikutus kevätrukiin satoon
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Selostus: Kasvunsääteiden vaikutukset tavanomaisen, paljasjyväisen ja kääpiökauran kasvuun ja sadonmuodostukseen
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Paper presented in ISA RC23 meeting, Gothenburg July 16th 2010
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The goal of this study was to find a new approach to modify chemically the properties of paper by improving fiber quality. This Master’s thesis includes the multiple polymer treatment in general and themeasurement methods with which the formation of multilayers and complexes can be noticed. The treatment by an oppositely charged dual polymer system is a good approach to increase paper strength. In this work, starch, a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used step-by-step to improve paper strength. The adsorption of cationic starch and CMC on cellulose fibers were analyzed via polyelectrolyte titration. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the starch/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly.
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Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014
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The Kraft pulping process is the dominant chemical pulping process in the world. Roughly 195 million metric tons of black liquor are produced annually as a by-product from the Kraft pulping process. Black liquor consists of spent cooking chemicals and dissolved organics from the wood and can contain up to 0.15 wt% nitrogen on dry solids basis. The cooking chemicals from black liquor are recovered in a chemical recovery cycle. Water is evaporated in the first stage of the chemical recovery cycle, so the black liquor has a dry solids content of 65-85% prior to combustion. During combustion of black liquor, a portion of the black liquor nitrogen is volatilized, finally forming N2 or NO. The rest of the nitrogen remains in the char as char nitrogen. During char conversion, fixed carbon is burned off leaving the pulping chemicals as smelt, and the char nitrogen forms mostly smelt nitrogen (cyanate, OCN-). Smelt exits the recovery boiler and is dissolved in water. The cyanate from smelt decomposes in the presence of water, forming NH3, which causes nitrogen emissions from the rest of the chemical recovery cycle. This thesis had two focuses: firstly, to determine how the nitrogen chemistry in the recovery boiler is affected by modification of black liquor; and secondly, to find out what causes cyanate formation during thermal conversion, and which parameters affect cyanate formation and decomposition during thermal conversion of black liquor. The fate of added biosludge nitrogen in chemical recovery was determined in Paper I. The added biosludge increased the nitrogen content of black liquor. At the pulp mill, the added biosludge did not increase the NO formation in the recovery boiler, but instead increased the amount of cyanate in green liquor. The increased cyanate caused more NH3 formation, which increased the NCG boiler’s NO emissions. Laboratory-scale experiments showed an increase in both NO and cyanate formation after biosludge addition. Black liquor can be modified, for example by addition of a solid biomass to increase the energy density of black liquor, or by separation of lignin from black liquor by precipitation. The precipitated lignin can be utilized in the production of green chemicals or as a fuel. In Papers II and III, laboratory-scale experiments were conducted to determine the impact of black liquor modification on NO and cyanate formation. Removal of lignin from black liquor reduced the nitrogen content of the black liquor. In most cases NO and cyanate formation decreased with increasing lignin removal; the exception was NO formation from lignin lean soda liquors. The addition of biomass to black liquor resulted in a higher nitrogen content fuel mixture, due to the higher nitrogen content of biomass compared to black liquor. More NO and cyanate were formed from the fuel mixtures than from pure black liquor. The increased amount of formed cyanate led to the hypothesis that black liquor is catalytically active and converts a portion of the nitrogen in the mixed fuel to cyanate. The mechanism behind cyanate formation during thermal conversion of black liquor was not clear before this thesis. Paper IV studies the cyanate formation of alkali metal loaded fuels during gasification in a CO2 atmosphere. The salts K2CO3, Na2CO3, and K2SO4 all promoted char nitrogen to cyanate conversion during gasification, while KCl and CaCO3 did not. It is now assumed that cyanate is formed when alkali metal carbonate or an active intermediate of alkali metal carbonate (e.g. -CO2K) reacts with the char nitrogen forming cyanate. By testing different fuels (bark, peat, and coal), each of which had a different form of organic nitrogen, it was concluded that the form of organic nitrogen in char also has an impact on cyanate formation. Cyanate can be formed during pyrolysis of black liquor, but at temperatures 900°C or above, the formed cyanate will decompose. Cyanate formation in gasifying conditions with different levels of CO2 in the atmosphere was also studied. Most of the char nitrogen was converted to cyanate during gasification at 800-900°C in 13-50% CO2 in N2, and only 5% of the initial fuel nitrogen was converted to NO during char conversion. The formed smelt cyanate was stable at 800°C 13% CO2, while it decomposed at 900°C 13% CO2. The cyanate decomposition was faster at higher temperatures and in oxygen-containing atmospheres than in an inert atmosphere. The presence of CO2 in oxygencontaining atmospheres slowed down the decomposition of cyanate. This work will provide new information on how modification of black liquor affects the nitrogen chemistry during thermal conversion of black liquor and what causes cyanate formation during thermal conversion of black liquor. The formation and decomposition of cyanate was studied in order to provide new data, which would be useful in modeling of nitrogen chemistry in the recovery boiler.
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Tavallisten hapetusmenetelmien sijasta kehittyneitä hapetusmenetelmiä (AOP) on kehitetty yhä enemmän, jotta hapetusprosessista tulisi kannattavampi, tehokkaampi, ympäristöystävällisempi ja sitä voitaisiin hyödyntää laajalti eri paikoissa. Uusi teknologia, joka käyttää otsonia ja hydroksyyliradikaalia sähköimpulssien kanssa, on yksi mahdollinen tehokkaampi vedenkäsittelymentelmä. Kyseistä menetelmää kutsutaa pulsed corona discharge (PCD) -menetelmäksi, joka käyttää prosessissa muodostuvia otsonia ja hydroksyyliradikaalia hapettavina tekijöinä. Tässä työssä tutkittiin nitraatin muodostumista vedessä, kun vettä käsiteltiin PCD-laitteessa ja, kun oksalaatti- ja formaatti-ioneja oli sekoittuneina veteen. Nitraatteja muodostuu PCD–laitteessa veteen, kun ilman typpi reagoi hapettimina toimivien otsonin ja hydroksyyliradikaalin kanssa. Aiemmissa tutkimuksissa nitraatin muodostumisen on todistettu parantuvan, kun karboksyylihapot muurahais- ja oksaalihappo ovat sekoittuneina veteen. Tässä tutkimuksessa tarkoituksena oli tutkia, miten formaatti- ja oksalaatti-ionien, joiden pitoisuudet olivat 0 ppm, 50 ppm ja 100 ppm, läsnäolo vedessä vaikuttaa nitraatin muodostumiseen. PCD-kokeista saadut näytteet analysoitiin ionikromatografilla. Kyseisessä tutkimuksessa nitraatin muodostuminen oli samansuuruista jokaisessa kokeessa hapetusajan kasvaessa samalla, kun otettujen näytteiden pH-arvot laskivat. Tuloksena voitiin pitää sitä, ettei formaatti- tai oksalaatti-ioneilla ollut vaikutusta nitraatti-ionien muodostumiseen.
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The aim of this dissertation was to examine the skills and knowledge that pre-service teachers and teachers have and need about working with multilingual and multicultural students from immigrant backgrounds. The specific goals were to identify pre-service teachers’ and practising teachers’ current knowledge and awareness of culturally and linguistically responsive teaching, identify a profile of their strengths and needs, and devise appropriate professional development support and ways to prepare teachers to become equitable culturally responsive practitioners. To investigate these issues, the dissertation reports on six original empirical studies within two groups of teachers: international pre-service teacher education students from over 25 different countries as well as pre-service and practising Finnish teachers. The international pre-service teacher sample consisted of (n = 38, study I; and n = 45, studies II-IV) and the pre-service and practising Finnish teachers sample encompassed (n = 89, study V; and n = 380, study VI). The data used were multi-source including both qualitative (students’ written work from the course including journals, final reflections, pre- and post-definition of key terms, as well as course evaluation and focus group transcripts) and quantitative (multi-item questionnaires with open-ended options), which enhanced the credibility of the findings resulting in the triangulation of data. Cluster analytic procedures, multivariate analysis of variance (MANOVA), and qualitative analyses mostly Constant Comparative Approach were used to understand pre-service teachers’ and practising teachers’ developing cultural understandings. The results revealed that the mainly white / mainstream teacher candidates in teacher education programmes bring limited background experiences, prior socialisation, and skills about diversity. Taking a multicultural education course where identity development was a focus, positively influenced teacher candidates’ knowledge and attitudes toward diversity. The results revealed approaches and strategies that matter most in preparing teachers for culturally responsive teaching, including but not exclusively, small group activities and discussions, critical reflection, and field immersion. This suggests that there are already some tools to address the need for the support needed to teach successfully a diversity of pupils and provide in-service training for those already practising the teaching profession. The results provide insight into aspects of teachers’ knowledge about both the linguistic and cultural needs of their students, as well as what constitutes a repertoire of approaches and strategies to assure students’ academic success. Teachers’ knowledge of diversity can be categorised into sound awareness, average awareness, and low awareness. Knowledge of diversity was important in teachers’ abilities to use students’ language and culture to enhance acquisition of academic content, work effectively with multilingual learners’ parents/guardians, learn about the cultural backgrounds of multilingual learners, link multilingual learners’ prior knowledge and experience to instruction, and modify classroom instruction for multilingual learners. These findings support the development of a competency based model and can be used to frame the studies of pre-service teachers, as well as the professional development of practising teachers in increasingly diverse contexts. The present set of studies take on new significance in the current context of increasing waves of migration to Europe in general and Finland in particular. They suggest that teacher education programmes can equip teachers with the necessary attitudes, skills, and knowledge to enable them work effectively with students from different ethnic and language backgrounds as they enter the teaching profession. The findings also help to refine the tools and approaches to measuring the competencies of teachers teaching in mainstream classrooms and candidates in preparation.
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Internationalization represents a complex topic that has been researched for quite some time. However, since it continues to be extremely current a topic, its significance has not diminished, but maybe even increased in importance. Companies today face extreme pressure to enter new markets in the hope of growing, becoming more profitable, increasing market share, attracting new customers and meeting the requirements of its share- and stakeholders. In the increasingly global business environment of today, companies are facing both challenges and possible advantages of internationalization. Few companies are not operating internationally and it is becoming the question of ‘Why not?’ rather than ‘Why?’ to internationalize business operations. Internationalization and the importance of strategy are discussed in this research from the viewpoint of three case companies that were interviewed about internationalization strategies. This research project is a qualitative study that answers the research question of How is a business strategy constructed for entering a new market? The sub-questions are • How are goals set and what indicators are used to monitor the achievement of these goals? • What are the key characteristics of a strategy implementation process? The research method chosen for this study is a multiple-case study. Three case companies were chosen for the interviews in order to gain in-depth data of internationalization strategies within the construction industry.
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The purpose of this study was to explore the employer brand image and its formation of a Finnish (yet international) service company in B2B sector. In the research qualitative case study method was used to explore the most preferred attributes in employer attraction, the employer brand perceptions towards the case company, and the effectors behind these brand perceptions among the prospective group of employees. The research was conducted through in-depth semistructured interviews among 23-30 undergraduate or graduate business students in Finnish universities close to their graduation. After deriving the attributes of an attractive employer, and exploring their relation to the case company, the employer brand image of the case company was determined and its attractiveness level evaluated. Moreover, the formation of the employer brand image was investigated and its sources detected. The most important factors for the target group in employer attractiveness were found to be company reputation and company culture/work atmosphere. Also career opportunities and international opportunities were seen important. The case company was found to hold a positive, attractive image on company culture and international opportunities, but failing to hold a good reputation as a fair employer. The main and most impactful source of employer brand image was former and current employees - directly or indirectly. Company’s own actions played only small part in employer brand formation as credibility is a critical factor in brand image formation and corporate communication found not to be perceived genuine. Based on the findings, suggestions for further employer branding were made.
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The purpose of this study is to identify the factors affecting the formation of employer image and attractiveness in the minds of an organization’s employees. Six employees from different backgrounds and business units within a larger organization are interviewed, and the results are compared in order to better understand the effect divergent variables have on the resulting factors. The theoretical background of the research is based on the study of the concept of employer branding, an organization’s effort in affecting the employer image it projects and attractiveness perceived by the employees and applicants. The results of the study reveal how immaterial factors, primarily related to self-actualization and social relationships, often took precedence over material ones, so long as the material factors, such as salary and work equipment, were at least on a minimum level acceptable to the employee. As such, focusing on these immaterial factors when forming an employer brand strategy is expected to yield larger benefits in form of employer attractiveness.