Browsing by Author "Virtanen, Heini"

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    Development of bioactive paper based on Trametes versicolor laccase
    (2010) Virtanen, Heini; Smolander, Maria; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Laakso, Simo
    The aim of this thesis was to develop bioactive paper based on Trametes versicolor laccase enzyme. Bioactive paper is a paper or paper-like product that includes functionalities based on selective reactions of bioactive compounds, such as enzymes. Laccases catalyze the oxidation of many phenolic substrates with simultaneous reduction of oxygen to water. Many of laccase substrates, such as ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-6- sulphonic acid)) also change colour while oxidizing. Therefore, laccase based bioactive paper could be used for oxygen scavenging and oxygen indicating applications. These applications are further explored by reviewing previous studies and inventions. In this study, the bioactive ink composition was first developed. The stability and activity of T. versicolor laccase was determined on various solutions. Next, T. versicolor laccase was coated on different substrates with various polymers with and without additives. Various ink compositions and coating substrates were compared by evaluating the laccase activity of paper samples containing the different bioactive coatings. Besides, the surface profile of the paper samples was investigated by measuring roughness with profilometer. Finally, the indicator performance was examined. The colour changing reaction of ABTS was observed visually and instrumentally by applying ABTS solution to the papers containing laccase based ink. Based on the determination of the optimum pH for T. versicolor laccase activity (pH < 4.5 with ABTS substrate) and stability (pH 7 - 9), pH 6 was chosen for further use. Sulfo polyester resin, HZ1100D was a favourable coating component. The tests proved that laccase cannot retain its activity long time on papers without any ink. When laccase was coated with HZ1100D, laccase activity typically did not significantly decrease during eight weeks of storage. Additives enhanced the stability of laccase in solutions, but not on the paper with the coating. EUCA paper proved to be a good substrate for laccase based coating. The colour changing reaction of ABTS on EUCA paper was rapid and excellent colour change from colourless to dark green was observed on the paper samples containing laccase. The findings of the study indicate that T. versicolor laccase can be used together with HZ1100D polymer dispersion to prepare functional bioactive paper products. These kinds of bioactive paper products were found to be particularly useful for indicator applications. However, when used in oxygen scavenging applications, calculations suggest that more optimization is needed.
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    Kasvien eteeristen öljyjen antimikrobisuus elintarvikkeissa
    (2008) Virtanen, Heini; Vahvaselkä, Marjatta; Kemian ja materiaalitieteiden tiedekunta; Nordström, Katrina
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    Methods for evaluating user experience in small agile teams: a case study
    (2022-07-29) Virtanen, Heini; Kauppinen, Marjo; Perustieteiden korkeakoulu; Kauppinen, Marjo
    For over a decade user experience (UX) has been one of the key considerations of software companies designing and developing digital services. At the same time, agile methods have become the mainstream in the industry to develop digital products and services. However, the previous studies have identified that agile methods don’t incorporate and ensure good user experience by default. Moreover, the studies have found that there is limited amount of research done investigating the UX practices from the perspective of small agile teams. The goal of this thesis was to investigate which evaluation methods are useful for small agile teams to improve the user experience of digital services. The empirical study was conducted as insider action research within a case company. The data was collected as research diary entries that were analyzed each time after new entries. Based on the literature review, 13 user experience evaluation methods were found to be used by agile teams. Among those, three methods were applied to the empirical case study: a qualitative online survey, semi-structured interviews and observation with thinking aloud. Based on the empirical study, the survey enabled relatively easily gathering concrete examples of issues, confusing areas, and suggestions as well as prioritizing the feedback. This data could be directly used for improving the UX of the service. This most useful information was gained mainly by analyzing the responses to the open-ended questions. The interviews worked well in situations where an accurate description of an issue or additional contextual information was needed to gain deep understanding of the events that influence the UX. The observation with thinking aloud provided the most varying data in understanding the different aspects of the UX. The rich visual and verbal data provided also multiple actionable improvement ideas that could be used for improving the UX of the service. The findings show that all the three UX evaluation methods, the survey, the interviews and the observation with thinking aloud, are useful for small agile teams to improve the UX of digital services. The observation with thinking aloud can help gathering the most useful and actionable data to be directly used for improving the UX of digital services, followed by the survey and last the interview. To evaluate the UX holistically to improve the UX of digital services, it’s good to combine multiple different UX evaluation methods.