Hermetic sealing of food packaging trays

Suojakaasupakkaaminen on lisääntynyt voimakkaasti viime vuosina elintarvikkeiden pakkaamisessa sillä pakkaamalla elintarvike suojakaasuun voidaan sen hyllyikää pidentää ilman säilöntäaineita. Tällainen pakkaaminen vaatii kuitenkin täysin kaasutiiviin pakkauksen, jonka kaasunläpäisevyys on myös alhainen. Yleisimmin käytetyt pakkausmateriaalit suojakaasupakkaamisessa ovat monikerroksiset muovimateriaalit, joissa yhdistyy monen eri muovin parhaimmat ominaisuudet. Yleisimmin käytettyjä muovilaatuja näissä monikerrosrakenteissa ovat PE, PET, PA ja EVOH polymeerit. Myös muita perinteisiä polymeerejä käytetään jonkin verran näissä rakenteissa. Uudemmat muovilaadut, kuten biohajoavat muovit, eivät ole vielä yleistyneet kaupallisessa käytössä pääasiallisesti niiden korkean hinnan vuoksi. Muovisten pakkausten korvaamista esimerkiksi muovipäällystetyillä kartonkipakkauksilla on viime vuosien aikana tutkittu enenevissä määrin. Muovipakkausten korvaamista helpommin kierrätettävillä ja mahdollisesti biohajoavilla materiaaleilla edistävät EU:n direktiivit, jotka käsittelevät pakkausjätteen käsittelyä. Kartonkivuokien saumaamista kaasutiiviisti tutkittiin myös tässä työssä. Tavoitteena oli löytää pakkaus, joka soveltuisi kanasuikaleiden pakkaamiseen suojakaasuun. Kana on herkkä mikrobiologiselle hajoamiselle, minkä johdosta se tulee pakata suojakaasuun jossa happipitoisuuden tulee olla alle 1 % pakkauspäivästä viimeiseen käyttöpäivään saakka. Suorittamalla erilaisia tiiveystutkimuksia voitiin osoittaa, että kartonkivuoka on mahdollista saumata kaasutiiviisti luotettavalla tavalla. Tämä vaatii kuitenkin kartonkivuokien valmistuksen optimoimista päällystemuovikerroksen ja kartongin paksuuden mukaan sekä kannen saumaamista optimoiduilla saumausparametreilla. Tiivein vuoka saavutettiin muovifilmikannella, jonka saumaus perustui samaan muoviin kuin vuoan saumaus. Polyeteenillä saavutettiin tiivein ja kestävin saumaustulos.

The Sedimentology, Ichnology and Hydrogeochemistry of the Late Miocene, Marginal Marine, Upper Pebas and Nauta Formations, Amazonian Foreland Basin, Peru

This thesis includes detailed sedimentological and ichnological studies on two geological units: the Pebas Formation, with a special focus in its informal upper member, and the Nauta Formation. Both formations were deposited during the Miocene in Northeastern Peruvian Amazonia, in the Amazon retroarc foreland basin. The Pebas and Nauta successions mainly consist of non-consolidated, clastic sedimentary deposits arranged into sand- to mud-dominated heterolithic successions, which can be upward-coarsening to upward-fining. Sediments in both the Pebas and Nauta successions range from mud to fine- to medium-grained sand. The main facies observed were 1) mud-dominated horizontal heterolithic couplets; 2) rooted brownish mud; 3) lenticular, mud-draped, cross-stratified sand; 4) mud- to sand-dominated, inclined heterolithic stratification; 5) sand-dominated horizontal heterolithic couplets; and 6) mud-draped, trough cross-stratified sand. Locally, tidal rhythmites were documented. The facies are interpreted as: 1) muddy, shallow, subaqueous flats/shoals; 2) palaeosols; 3) secondary tidal channels or run-off creeks; 4) tidally influenced point bars; 5) shoreface deposits; and 6) subtidal compound dunes. Thalassinoides-dominated Glossifungites ichnofacies, low-diversity expressions of the Skolithos ichnofacies and depauperate suites consisting of elements common to the Cruziana ichnofacies strongly indicate brackish-water conditions. However, continental trace fossil assemblages, with possible elements common to the Scoyenia ichnofacies, have also been identified. In addition to the palaeoenvironmental study, a local hydrogeochemical characterisation of the Pebas and Nauta formations was also conducted. The geochemistry of the groundwaters reflects the characteristics and the soil geochemistry of the geological formations studied. The Pebas formation has low hardness, acid to neutral waters, whereas the upper Pebas has high hardness, acid to neutral waters. In both units, the arsenic content is locally high. The Nauta formation has low hardness acid groundwaters. A regional review of the Pebas and Nauta formations placed the local observations into a continental perspective and suggests that the whole Pebas-Nauta system was a probably shallow (some tens of metres at maximum), brackish- to freshwater, tidally-influenced epicontinental embayment with a probable semi-diurnal to mixed tidal regime and a microtidal range, surrounded by continental environments such as forest floors, lagoons, rivers and their flood plains, and lakes.

Leak-proof Heat Sealing of Press-Formed Paperboard Trays

Three-dimensional (3D) forming of paperboard and heat sealing of lidding films to trays manufactured by the press forming process are investigated in this thesis. The aim of the work was to investigate and recognize the factors affecting the quality of heat sealing and the leak resistance (tightness) of press-formed, polymer-coated paperboard trays heatsealed with a multi-layer polymer based lidding film. One target was to achieve a solution that can be used in food packaging using modified atmosphere packaging (MAP). The main challenge in acquiring adequate tightness properties for the use of MAP is creases in the sealing area of the paperboard trays which can act as capillary tubes and prevent leak-proof sealing. Several experiments were made to investigate the effect of different factors and process parameters in the forming and sealing processes. Also different methods of analysis, such as microscopic analysis and 3D-profilometry were used to investigate the structure of the creases in the sealing area, and to analyse the surface characteristics of the tray flange of the formed trays to define quality that can be sealed with satisfactory tightness for the use of MAP. The main factors and parameters that had an effect on the result of leak-proof sealing and must be adjusted accordingly were the tray geometry and dimensions, blank holding force in press forming, surface roughness of the sealing area, the geometry and depth of the creases, and the sealing pressure. The results show that the quality of press-formed, polymer-coated paperboard trays and multi-layer polymer lidding films can be satisfactory for the use of modified atmosphere packaging in food solutions. Suitable tools, materials, and process parameters have to be selected and used during the tray manufacturing process and lid sealing process, however. Utilizing these solutions and results makes it possible for a package that is made mostly from renewable and recyclable sources to be a considerable alternative for packages made completely from oil based polymers, and to achieve a greater market share for fibre-based solutions in food packaging using MAP.

Naiskomiikka : huumorista stand upiin, naurusta valtaan

The final project deals with the question of female comedy and the comedy made by women. Comedy has traditionally been made by men and the woman has been the one who laughs. A funny woman has been a rare phenomenon. Although times have changed and gender roles have become more flexible, female comedians still remain in a minority compared to their male colleagues. The essay reviews the social and historical structures that influence the position of women in general and on the field of comedy in particular. The teoretical basis to this is feminist theory. Female comedy and humour have features of their own, that are being examined in the essay. It also makes a difference between feminine comedy and feminist comedy. Largely the project handles stand up comedy. The popularity of stand up comedy has changed the field of professional entertainment and brought a number of widely gifted comedians to a common knowledge. Stand up has an opportunity to be a political tool, which is essential for marginal comedians, which also includes female comedians. One of the fundamental subjects of the project is the political character of comedy. The essay also portrays the historical roots of stand up comedy in the Finnish and in the American tradition. It reflects on the fore mothers of the modern female comedian. The reasons that make a woman become a comedian are under consideration, as well as the strategies that help her to get her voice and message delivered. Since a woman is still held in the marginal, it gives female comedy a feature of its own. This way comedy can become a tool for a feminist battle.

Clinical Learning Environment and Supervision. Development and Validation of the CLES Evaluation Scale

The purpose of the study is: (1) to describe how nursing students' experienced their clinical learning environment and the supervision given by staff nurses working in hospital settings; and (2) to develop and test an evaluation scale of Clinical Learning Environment and Supervision (CLES). The study has been carried out in different phases. The pilot study (n=163) explored the association between the characteristics of a ward and its evaluation as a learning environment by students. The second version of research instrument (which was developed by the results of this pilot study) were tested by an expert panel (n=9 nurse teachers) and test-retest group formed by student nurses (n=38). After this evaluative phase, the CLES was formed as the basic research instrument for this study and it was tested with the Finnish main sample (n=416). In this phase, a concurrent validity instrument (Dunn & Burnett 1995) was used to confirm the validation process of CLES. The international comparative study was made by comparing the Finnish main sample with a British sample (n=142). The international comparative study was necessary for two reasons. In the instrument developing process, there is a need to test the new instrument in some other nursing culture. Other reason for comparative international study is the reflecting the impact of open employment markets in the European Union (EU) on the need to evaluate and to integrate EU health care educational systems. The results showed that the individualised supervision system is the most used supervision model and the supervisory relationship with personal mentor is the most meaningful single element of supervision evaluated by nursing students. The ward atmosphere and the management style of ward manager are the most important environmental factors of the clinical ward. The study integrates two theoretical elements - learning environment and supervision - in developing a preliminary theoretical model. The comparative international study showed that, Finnish students were more satisfied and evaluated their clinical placements and supervision with higher scores than students in the United Kingdom (UK). The difference between groups was statistical highly significant (p= 0.000). In the UK, clinical placements were longer but students met their nurse teachers less frequently than students in Finland. Arrangements for supervision were similar. This research process has produced the evaluation scale (CLES), which can be used in research and quality assessments of clinical learning environment and supervision in Finland and in the UK. CLES consists of 27 items and it is sub-divided into five sub-dimensions. Cronbach's alpha coefficient varied from high 0.94 to marginal 0.73. CLES is a compact evaluation scale and user-friendliness makes it suitable for continuing evaluation.