LWC-paperin opasiteetin parantaminen

LWC-syväpainopaperilta vaaditaan hyvän ajettavuuden, kiillon ja sileyden ohella hyvää opasiteettia. Tämä on asettanut haasteita LWC-paperin valmistajille paperin neliömassojen laskiessa. Tässä diplomityössä etsittiin keinoja parantaa kevyiden LWC-syväpainolajien opasiteettia heikentämättä oleellisesti muita tärkeitä paperin ominaisuuksia. Tavoitteena oli nostaa CR48-lajin opasiteetti tavoitearvoon 90 %. Työn kirjallisuusosassa perehdyttiin paperin optisten ominaisuuksien teoriaan sekä raaka-aineisiin ja prosessin osiin, joilla on vaikutusta paperin opasiteettiin. Työn kokeellisessa osassa tutkittiin olemassa olevan aineiston perusteella tekijöitä, joilla uskottiin olevan vaikutusta CR48-lajin opasiteettiin. Tutkimuksen ja kirjallisuuden perusteella ajettiin tehdaskoeajoa, joiden avulla pyrittiin parantamaan paperin opasiteettia. CR48-lajin opasiteettitavoite saavutettiin kolmella eri tavalla. Opasiteettitavoite saavutettiin, kun paperin vaaleus säädettiin tavoitearvoon pigmenttivärin avulla tumman hierteen sijasta. Tällöin väripigmentin määrää päällystyspastassa nostettiin 0,01 osaa ja valkaistun hierteen osuus kokonaishierteen määrästä oli 100 %. Vaaleuden säätö pastavärillä oli käytännössä hidasta ja hankalaa. Opasiteettitavoite saavutettiin myös, kun hierre jauhettiin täysin koeterillä. Koeterillä tapahtuva jauhatus oli rajumpaa ja katkovampaa kuin perinteisillä terillä, joten hienoaineen lisääntyminen ja kuidun lyheneminen paransivat paperin opasiteettia, mutta lujuudet huononivat. Lisäksi tavoiteopasiteetti saavutettiin, kun sellun osuutta vähennettiin 8 %-yksikköä. Lujuuden säilymisen kannalta sellun vähennys oli parempi keino opasiteetin parantamiseksi kuin hierteen jauhaminen koeterillä. Koeajojen perusteella pohjapaperin tuhkapitoisuuden nostolla ja hierteen CSF-luvun alentamisella ei ollut vaikutusta paperin opasiteettiin. Lisäksi 100 %:nen koeterillä jauhettu sahahakehierre antoi paperille huonomman opasiteetin kuin hierre, josta puolet oli jauhettu koeterillä ja raaka-aineesta 25 % oli sahahaketta.

Paperin puhtauden parantaminen lajittelun ja muiden prosessiteknisten keinojen avulla

Tämä työ suoritettiin UPM- Kymmene Oyj:n Tervasaaren tehtaan PK 5:llä. PK 5 valmistaa tarrantaustapaperia. Tämän työn tarkoituksena oli löytää eri keinoja paperin puhtauden parantamiseksi. Puhtaamman paperin valmistaminen parantaa paperikoneen kilpailukykyä kilpailijoihinsa nähden sekä vähentää asiakasvalituskustannuksia. Työn kirjallinen osa koostuu kolmesta suuremmasta kokonaisuudesta, joiden tarkoituksena on luoda teoriapohjaa kokeellisen osan suoritusta varten. Kirjallisuusosan pääpaino on kohdistettu PK 5:llä esiintyviin saostumanaiheuttajiin, kuten uuteaineisiin, ASA- liimaan ja mikrobeihin. Tarkemmassa tarkastelussa on kirjallisuusosassa myös painelajittelu ja pyörrepuhdistus. Kokeellisessa osassa suoritettiin PK 5:n prosessissa syntyvien epäpuhtauksien karakterisointi. Suurimmat saostuman aiheuttajat analyysien perusteella olivat puuperäiset uuteaineet ja ASA- liima. Epäorgaanisista aineista päällystyskomponenttina toimiva kaoliini ja sellun mukana tuleva pihkatalkki esiintyi useimpien saostumien komponentteina. Selvityksessä havaittiin, että prosessille vieraita aineita ei löydetty muista, kuin kalanteroidusta paperista analysoiduista tummista täplistä. Tummista täplistä analysoitu styreenin alkuperä voi selittyä mm. prosessiin päässeellä kumilla tai muovilla. PK 5:n prosessissa selvityksen mukaan silikonipohjainen vaahdonestoaine aiheuttaa erittäin suuria tummia saostumia, joten sen pääsy prosessiin tulee estää sellutehtaalla tarkoin. Epäpuhtauksien määrä on suurin PK 5:n prosessissa hylkylinjassa ja lyhyessä kierrossa. Hylyn painelajittelu poistaa hyvin roskia syöttömassasta. Hylyn lajittelun toisen portaan lajittimen rejektin roskapitoisuus on suhteellisen suuri. Rejektin ohjaaminen ulos prosessista vähentää roskaisuuden rikastumista prosessiin. Sakeamassalajittelun sijoittaminen PK 5:n konekyypin jälkeen vähentää roskien päätymistä paperiin. Hylyn painelajittelun ja PP- laitoksen rejektin ohjaaminen sakeamassalajittelun toiseen portaaseen vähentäisi priimakuitutappiota ja roskien määrää käytetyissä massoissa. Seisokin aikaisen putkilinjojen pesujen lopputulos parani huomattavasti BA- pesuaineen käyttöönoton jälkeen. Kyseisen pesuaine soveltuu liuottamaan putkistosta mm. PK 5:llä esiintyvät uuteaine- ja ASA- saostumat. BSA- sellun pH- säädön lopettamisella oli suuri vähentävä vaikutus tummien täplien esiintymistiheyteen. pH- säädössä BSA- tornin pohjalaimennukseen annosteltu lipeä edesauttoi tummien saostumien syntymistä saippuoiden uuteaineita.

Ikääntyvät työelämässä. Päihittääkö nuoruus ja koulutus aikuisuuden ja kokemuksen?

The Ageing in Working Life. Do Adolescence and Schooling Beat Adulthood and Experience? This study examines the changes in the work and the work organisations of employees in the fields of health care and retail trade who have turned 45 and their experience of change. In addition, the question of how ageing employees experience their status in post-modern working life is explored. Attention is also focused on the choices and decisions connected with staying at work and retiring. These views are examined in relation to professions and professional cultures. Thematic interviews (N=98) were used to gather the material. The effects of the market liberalistic turn in welfare policy are clearly seen in the everyday work of the health care professions. These changes were examined from the point of view of managing by outcomes and quality assurance, multi-professional cooperation, flexibility in the division of labour, and the spread of market-like procedures. The discourse of those in involved retail trade was dominated by extremely tight global market competition and control of outcomes, and by the structural changes taking place in the retail trade sector. This change discourse was to a large extent a reaction to those changes in the functional environment which were experienced as negative and to the conflict between their own professional identity and professional ethics on the one hand, and their functional environment on the other. There were also obstacles connected with professional culture: defending one's own station and power, guarding the 'frontier', showed up in attitudes towards new management and organisation models or towards structural and functional reforms. The deep structures of professional culture and the mindset of the actors change much more slowly than the functional practices of organisations. For those in a supervisory position, the loss of power due to becoming part of a chain or because of the introduction of a team organisation model was not an easy thing to accept. The nurses and others in related fields felt that they were forced to do work that was below their level of training and professional skill. For sales personnel and those who did assisting work in health care, power and the possibility of having an influence were not so important, as long as they were able to do their work in their own way and were trusted. This view is often completely forgotten, for example, in various organisation models in which power and the possibility of having an influence entwined with power are taken for granted as being clearly positive and desired aspects of job satisfaction. Up to date professional skills were experienced as being important from the point of view of professional identity and self-worth. Thus, training can be understood as a moral obligation, which in turn is intertwined with professional ideology. In the rhetoric of adult education, an adult is expected to be an active player who will seek training again and again if working life so requires. The dark side of this ideology, which leads to feelings of guilt, was apparent in the thoughts of the respondents. Am I never good enough at my job; why must I continually strive for better, additional qualifications? The majority of the respondents evaluated their expertise as being at quite a high level. This self-confidence did not extend to applying for a job. Job recruitment was seen as a situation in which age discrimination reached its peak. The interviewees were unanimous about the idea that society favours the young. Especially among those in the retail trade sector, there was a feeling that it would be difficult, if not impossible, to find a new job of the same level or a permanent post if they were made redundant. Age discrimination was also apparent in the retail trade field in the form of older employees being retired against their will or transferred to other tasks. It was felt that ruthless forced retirement of older workers was part of the personnel policy of some organisations. The importance of one's outward appearance was connected with the theme of discrimination. This phenomenon is described using the concept of the double standard of ageing in feminist research. An ageing woman is relegated to an inferior position due to both her age and her sex. A culture that would both make possible and allow various types of choices regardless of age, which is described as being characteristic of the post-modern era, does not seem to be very topical in the practice of working life. It is important for employees that the management and the personnel policy that is being implemented makes them feel like both their contribution and they as individuals are appreciated, that their opinions are listened to and that they are noticed as persons. The interviewees hoped for gratitude and a concern for the well-being of employees that shows in everyday life. They valued training and activities aimed at maintaining their work ability, but thought that better coping at work and a pleasant working environment cannot be achieved through such measures as along as the foundation is 'in a mess'. Development of the quality of working life is the only thing that can improve job satisfaction and get people to remain in the work force longer than at present. There should be a sufficient number of properly trained employees at the work place. It was important to the respondents that they be able to stay on their job to the end with honour, since compromising with their own quality standards or acting contrary to their ideal self-image in terms of professional ethics would strike a blow to their professional self-esteem. They called for the development of various types of workplace flexibility, and felt that they have the right to a lightened workload and to early retirement. Early retirement was even seen as an altruistic deed: it would free up a place for younger workers. Thoughts of retirements were explained by familiar factors such as health and finances, life situation, the enticement of free-time, as well as by various factors related to work. It is very important to ageing employees that their work has meaningful content. The values related to self-fulfilment are felt to be of great importance, and if they cannot be realised at work, the respondents wanted more free time, either through retirement or in the form of flexibility in working life.

Kirjat

Kirjallisuusarvostelu

Uskonnollinen Israel-ystävyys suurvaltapolitiikassa

Kirjallisuusarvostelu

24+1 kansainvälisten suhteiden perusoppikirjaa : havaintoja ja arvioita

Kirjallisuusarvostelu

Costs and Benefits of a Shared Digital Long-Term Preservation System

Paper presented at the 40th Annual Conference of LIBER (Ligue des Bibliothèques Européennes de Recherche - Association of European Research Libraries) on July 1st, 2011; with the slides used at the presentation.

NADPH-Dependent Thioredoxin System In Regulation of Chloroplast Functions

Photosynthesis, the process in which carbon dioxide is converted into sugars using the energy of sunlight, is vital for heterotrophic life on Earth. In plants, photosynthesis takes place in specific organelles called chloroplasts. During chloroplast biogenesis, light is a prerequisite for the development of functional photosynthetic structures. In addition to photosynthesis, a number of other metabolic processes such as nitrogen assimilation, the biosynthesis of fatty acids, amino acids, vitamins, and hormones are localized to plant chloroplasts. The biosynthetic pathways in chloroplasts are tightly regulated, and especially the reduction/oxidation (redox) signals play important roles in controlling many developmental and metabolic processes in chloroplasts. Thioredoxins are universal regulatory proteins that mediate redox signals in chloroplasts. They are able to modify the structure and function of their target proteins by reduction of disulfide bonds. Oxidized thioredoxins are restored via the action of thioredoxin reductases. Two thioredoxin reductase systems exist in plant chloroplasts, the NADPHdependent thioredoxin reductase C (NTRC) and ferredoxin-thioredoxin reductase (FTR). The ferredoxin-thioredoxin system that is linked to photosynthetic light reactions is involved in light-activation of chloroplast proteins. NADPH can be produced via both the photosynthetic electron transfer reactions in light, and in darkness via the pentose phosphate pathway. These different pathways of NADPH production enable the regulation of diverse metabolic pathways in chloroplasts by the NADPH-dependent thioredoxin system. In this thesis, the role of NADPH-dependent thioredoxin system in the redox-control of chloroplast development and metabolism was studied by characterization of Arabidopsis thaliana T-DNA insertion lines of NTRC gene (ntrc) and by identification of chloroplast proteins regulated by NTRC. The ntrc plants showed the strongest visible phenotypes when grown under short 8-h photoperiod. This indicates that i) chloroplast NADPH-dependent thioredoxin system is non-redundant to ferredoxinthioredoxin system and that ii) NTRC particularly controls the chloroplast processes that are easily imbalanced in daily light/dark rhythms with short day and long night. I identified four processes and the redox-regulated proteins therein that are potentially regulated by NTRC; i) chloroplast development, ii) starch biosynthesis, iii) aromatic amino acid biosynthesis and iv) detoxification of H₂O₂. Such regulation can be achieved directly by modulating the redox state of intramolecular or intermolecular disulfide bridges of enzymes, or by protecting enzymes from oxidation in conjunction with 2-cysteine peroxiredoxins. This thesis work also demonstrated that the enzymatic antioxidant systems in chloroplasts, ascorbate peroxidases, superoxide dismutase and NTRC-dependent 2-cysteine peroxiredoxins are tightly linked up to prevent the detrimental accumulation of reactive oxygen species in plants.

Cyanobacteria from the Baltic Sea and Finnish lakes as an energy source and modulators of bioenergetic pathways

Cyanobacteria are a diverse group of oxygenic photosynthetic bacteria that inhabit in a wide range of environments. They are versatile and multifaceted organisms with great possibilities for different biotechnological applications. For example, cyanobacteria produce molecular hydrogen (H2), which is one of the most important alternatives for clean and sustainable energy. Apart from being beneficial, cyanobacteria also possess harmful characteristics and may become a source of threat to human health and other living organisms, as they are able to form surface blooms that are producing a variety of toxic or bioactive compounds. The University of Helsinki Culture Collection (UHCC) maintains around 1,000 cyanobacterial strains representing a large number of genera and species isolated from the Baltic Sea and Finnish lakes. The culture collection covers different life forms such as unicellular and filamentous, N2-fixing and non-N2-fixing strains, and planktonic and benthic cyanobacteria. In this thesis, the UHCC has been screened to identify potential strains for sustainable biohydrogen production and also for strains that produce compounds modifying the bioenergetic pathways of other cyanobacteria or terrestrial plants. Among the 400 cyanobacterial strains screened so far, ten were identified as high H2-producing strains. The enzyme systems involved in H2 metabolism of cyanobacteria were analyzed using the Southern hybridization approach. This revealed the presence of the enzyme nitrogenase in all strains tested, while none of them are likely to have contained alternative nitrogenases. All the strains tested, except for two Calothrix strains, XSPORK 36C and XSPORK 11A, were suggested to contain both uptake and bidirectional hydrogenases. Moreover, 55 methanol extracts of various cyanobacterial strains were screened to identify potent bioactive compounds affecting the photosynthetic apparatus of the model cyanobacterium, Synechocystis PCC 6803. The extract from Nostoc XPORK 14A was the only one that modified the photosynthetic machinery and dark respiration. The compound responsible for this effect was identified, purified, and named M22. M22 demonstrated a dual-action mechanism: production of reactive oxygen species (ROS) under illumination and an unknown mechanism that also prevailed in the dark. During summer, the Baltic Sea is occupied by toxic blooms of Nodularia spumigena (hereafter referred to as N. spumigena), which produces a hepatotoxin called nodularin. Long-term exposure of the terrestrial plant spinach to nodularin was studied. Such treatment resulted in inhibition of growth and chlorosis of the leaves. Moreover, the activity and amount of mitochondrial electron transfer complexes increased in the leaves exposed to nodularin-containing extract, indicating upregulation of respiratory reactions, whereas no marked changes were detected in the structure or function of the photosynthetic machinery. Nodularin-exposed plants suffered from oxidative stress, evidenced by oxidative modifications of various proteins. Plants initiated strategies to combat the stress by increasing the levels of alpha-tocopherol, mitochondrial alternative oxidase (AOX), and mitochondrial ascorbate peroxidase (mAPX).