Browsing by Subject "characterization"

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  • Tamminen, Ida (Helsingfors universitet, 2017)
    Pro gradussani tarkastelen naishahmoja John Greenin kirjoissa Looking for Alaska, An Abundance of Katherines, Paper Towns ja The Fault in Our Stars. Tutkielmani tavoitteena on selvittää miten naishahmoja kuvataan Greenin kirjoissa ja miten se eroaa mieshahmojen kuvauksesta. Lisäksi pohdin mediarepresentaation tärkeyttä etenkin nuorille suunnatussa kirjallisuudessa sekä sitä, ovatko Greenin naishahmot autenttisen tuntuisia. Teoriataustana käytän teoksia hahmojentutkimuksen, feministisen kirjallisuusteorian, kerronnantutkimuksen ja stereotyyppientutkimuksen alueilta. Tutkimusmenetelmänäni on tekstin huolellinen lukeminen, eng. ’close reading’, teoria-aineistooni nojautuen. Aineistonani käytän Greenin kirjojen lisäksi hänen omia mielipiteitään, kommenttejaan ja vastauksiaan, joita hän on esittänyt lukuisissa blogeissaan. Pro graduni keskeisimpiä tuloksia on se, että naishahmot on esitetty eri tavalla kuin mieshahmot, etenkin kun kyseessä ovat muut kuin nimettömät sivuhenkilöt. Naishahmoihin liitetään enemmän fyysiseen viehättävyyteen liittyviä piirteitä ja heidät on kuvattu vähemmän persoonallisiksi kuin miespuoliset henkilöhahmot. Vaikka hahmonkehitystä tapahtuu, se on usein sidoksissa miespuoliseen päähenkilöön. Naispuoliset henkilöhahmot ovat myös miespäähenkilön epäluotettavan kerronnan varassa, The Fault in Our Stars pois lukien. Totean Greenin kirjojen olevan kohdistettu pääosin teini-ikäisille tytöille. Koska representaatio vaikuttaa sekä kuvaan omasta itsestä että toisista, on tärkeää että se olisi monipuolista. Greenin kirjoissa naishahmojen representaatio on melko yksipuolista, mikä vähentää autenttisuutta. Naishahmojen autenttisuutta edustaa parhaiten The Fault in Our Stars, koska siinä on naispäähenkilö, jonka kerrontatyyli on melko realistinen. Autenttisuutta luodaan myös henkilöhahmojen omilla stereotypioilla, maailmankuvilla, huumorilla ja luonteenpiirteillä, sekä kerronnan keinoin. Green ilmaisee monissa kommenteissa olevansa tietoinen kirjojensa puutteista etenkin vähemmistöjen edustamisen suhteen sekä naishahmojen roolien suhteen, ja tämä tiedostaminen näkyy verratessa The Fault in Our Starsin naiskertojaa muiden kirjojen mieskertojiin. Green tekee naishahmojen yksinkertaistetun kuvittelun ja romantisoinnin ongelmallisuutta selväksi myös kirjoissa, joissa se on esillä toistuvana teemana, etenkin Paper Townsissa.
  • Naaranoja, Tiina; Golovleva, Maria; Gädda, Akiko; Martikainen, Laura; Ott, Jennifer; Berretti, Mirko; Garcia, Francisco; Luukka, Panja; Tuuva, Tuure; Österberg, Kenneth (2019)
    The radiation hardness of diamond at the sensor level is studied by irradiating five sensors and studying them with various particle sources, without making any modifications to the sensors in between. The electronics used in the characterization is not irradiated to ensure that any observed effect is merely due to the sensor. Three sensors have received a fluence of 10 (14) protons cm(-2) and two 5 center dot 10 (15) protons cm(-2). At the lower fluence, the impact on the charge collection efficiency is very small, when the applied bias voltage is above 1 V mu m(-1). For the higher fluence, the charge collection efficiency is lower than expected based on earlier studies of diamond radiation hardness on the substrate level. Furthermore, it is noticed that the irradiation has a stronger impact on the signal amplitude recorded with a fast timing than with a charge sensitive amplifier.
  • Townsend, Eleanor M; Kelly, Lucy; Gannon, Lucy; Muscatt, George; Dunstan, Rhys; Michniewski, Slawomir; Sapkota, Hari; Kiljunen, Saija J; Kolsi, Anna; Skurnik, Mikael; Lithgow, Trevor; Millard, Andrew D; Jameson, Eleanor (2021)
    Introduction: Klebsiella is a clinically important pathogen causing a variety of antimicrobial resistant infections in both community and nosocomial settings, particularly pneumonia, urinary tract infection, and sepsis. Bacteriophage (phage) therapy is being considered a primary option for the treatment of drug-resistant infections of these types. Methods: We report the successful isolation and characterization of 30 novel, genetically diverse Klebsiella phages. Results: The isolated phages span six different phage families and nine genera, representing both lysogenic and lytic lifestyles. Individual Klebsiella phage isolates infected up to 11 of the 18 Klebsiella capsule types tested, and all 18 capsule-types were infected by at least one of the phages. Conclusions: Of the Klebsiella-infecting phages presented in this study, the lytic phages are most suitable for phage therapy, based on their broad host range, high virulence, short lysis period and given that they encode no known toxin or antimicrobial resistance genes. Phage isolates belonging to the Sugarlandvirus and Slopekvirus genera were deemed most suitable for phage therapy based on our characterization. Importantly, when applied alone, none of the characterized phages were able to suppress the growth of Klebsiella for more than 12 h, likely due to the inherent ease of Klebsiella to generate spontaneous phage-resistant mutants. This indicates that for successful phage therapy, a cocktail of multiple phages would be necessary to treat Klebsiella infections.
  • Björkroth, Johanna; Korkeala, Hannu (International Association for Food Protection, 1997)
    Spoilage characterized by bulging as a result of gas formation in bottled ketchup was studied and resulted in growth on MRS and Rogosa selective Lactobacillus agar. Seventy randomly selected isolates were typed using restriction endonuclease analysis (ClaI, EcoRI, HindIII) and were found to have identical patterns. The strain was identified as Lactobacillus fructivorans using morphological, physiological and biochemical characteristics, combined with information obtained from rRNA gene restriction patterns. Factors affecting growth and survival of this L. fructivorans strain in production circumstances were also studied. Lactobacillus count of 105 CFU/g resulted in spoilage of inoculated ketchup samples. Spoilage occurred only in samples incubated at 15 to 30°C. L. fructivorans implicated in causing spoilage demonstrated heat resistance with a D-value of 1.2 min at 65°C. The strain did not show resistance against alkaline, active chloride containing detergent sanitizer, and also alkyldimethylbenzyl ammonium chloride and alkyldimethylethylbenzyl ammonium chloride containing sanitizer was found to be effective against it.
  • Al-Hunaiti, Afnan; Ghazzy, Asma; Sweidan, Nuha; Mohaidat, Qassem; Bsoul, Ibrahim; Mahmood, Sami; Hussein, Tareq (2021)
    Here, we report on a phyto-mediated bimetallic (NiFe2O4) preparation using a Boswellia carterii extract, which was characterized by XRD, FT-IR, TGA, electron microscopy, magnetic spectroscopy, and Mössbauer spectroscopy measurements. The prepared nano-catalysts were tested for oxidation of lignin monomer molecules—vanillyl alcohol and cinnamyl alcohol. In comparison with previously reported methods, the nano NiFe2O4 catalysts showed high photocatalytic activity and selectivity, under visible light irradiation with a nitroxy radical initiator (2,2,6,6-tetramethylpiperidinyloxy or 2,2,6,6-tetramethylpiperidine 1-oxyl; TEMPO) at room temperature and aerobic conditions. The multifold advantages of the catalyst both in terms of reduced catalyst loading and ambient temperature conditions were manifested by higher conversion of the starting material.
  • Räty, Antti; Kekki, Tommi; Tanhua-Tyrkko, Merja; Lavonen, Tiina; Myllykyla, Emmi (2018)
    The objective of the study has been to verify the calculated residual activity in the decommissioning waste of the TRIGA Mark II-type research reactor FiR 1 in Finland. Knowledge of the radioactive inventory of irradiated materials is important in the planning of decommissioning activities and is essential for predicting the radiological impact to personnel and the environment. Measurements are performed for low active material samples from outer parts of the reactor. Methods include gamma spectrometric measurements, composition measurements with mass spectrometry, oxidation measurements of especially C-14 in graphite, and full combustion measurements of lithium-enriched shielding materials. Results are compared to estimates calculated with a combined Monte Carlo model of the reactor and a point-depletion code modeling the irradiation history. Decommissioning waste consists mainly of ordinary concrete, aluminum, steel, and graphite parts. Only preliminary measurements of low active samples are reported so far, but the same methods will be used later for characterizing and classifying dismantling waste. Some discussion of characterization requirements and future sampling is also included.
  • Kataja, Sara (Helsingin yliopisto, 2018)
    Production of biofuels from non-food-based materials, such as lignocellulose, provides a good alternative for the traditional burning of fossil fuels. Some of the researched and existing biofuel applications are based on the utilization of enzymes. There are multiple cellulolytic enzymes required in the efficient hydrolysis of lignocellulose, and one of the key enzyme group is β-glucosidases. These enzymatic systems are mainly adopted from wood-decaying fungi. The overall enzymatic system consists of different types of cellulases that first degrade the crystalline cellulose to oligosaccharides and cellobiose. In the final step, β-glucosidases hydrolyse the oligosaccharides to glucose (a fermentable sugar). In fact, β-glucosidases are one of the limiting enzyme classes in this process, due to phenomena such as end-product inhibition. β-Glucosidases belong to Glycoside hydrolases (GH), that can be classified into different protein families. In an industrial perspective, the main interest resides in GH1 and GH3 family enzymes. Many industrially relevant extracellular β-glucosidases belong to GH3 family. However, intracellular GH1 β-glucosidases often exhibit higher tolerance to harsh conditions such as high substrate and product concentrations, high temperatures and low pH. The goal of this MSc thesis work was to purify and characterize a novel GH1 β-glucosidase, named NBG. Both GH1 and GH3 family enzymes were used as references for the characterization work. The GH3 reference enzyme was a β-glucosidase from Aspergillus niger (An Cel3A), derived from the commercial enzyme preparation Novozym 188. The used GH1 reference was a β-glucosidase from termite Nasutitermes takasagoensis (Nt GH1). The applicability of NBG β-glucosidase in biomass hydrolysis was also examined, together with possible considerations for applicability by other type of applications. The purification of An Cel3 reference enzyme was performed as described previously in literature. A novel protocol combining thermal treatment and low resolution IEX purification was developed for the NBG enzyme in this study. The enzyme’s activity on various pNP-substrates was determined, followed by pH stability, thermostability and inhibition studies. According to the result, NBG is a potential candidate for industrial use. The enzyme was found to be thermostable and active in a wide pH range when compared to the reference enzymes (stable up to 20 h at +60 ˚C and in pH 3.5 – 6.0). NBG also exhibited wider activity on pNP-substrates than the reference enzymes, highest specific activity being on pNPG, followed by moderate activity on pNPFuc and low activities on pNPGal and pNPXyl. Furthermore, NBG exhibited higher tolerance to inhibitors such as glucose and ethanol. Glucose inhibition was not observed until concentration of 200 mM for NBG, while in the same concentration the reference enzymes were almost completely inhibited. A Clear activation (of +16 %) by 100 mM glucose was observed with NBG. This enzyme also outperformed the An Cel3A-reference in ethanol tolerance, retaining activity better in 15 and 20 % ethanol. Activation by ethanol was also observed for both of the fungal enzymes, the most pronounced effect being observed for NBG in 15 % ethanol (+21 % of initial activity). The hydrolysis of insoluble cellulosic substrate (Avicel) was investigated using a commercial cellulase mixture (Celluclast 1.5L), where a semi-pure β-glucosidase preparation was added: novel β-glucosidase preparation (NBG (2-S2)) or the reference preparation An Cel3A (Nz188). According to the results, the NBG (2S-2) was outperformed by An Cel3A (Nz188) in Avicel 4 – 72 h hydrolysis experiments. The amount of reducing sugars released from Avicel was approximately 18–19 % higher with the commercial Nz188 preparation when compared to the 2S-2 preparation. Further analyses of samples revealed accumulation of cello-oligosacchardes, which may accumulate due to two possible reasons: Either the NBG enzyme does not possess high enough cellobiase activity (needed in biomass hydrolysis to glucose), or accumulation of cellobiose is due to transglycosylation activity of NBG. According to activity (and 3D modelling) data, NBG may not be a true β-glucosidase belonging to the EC 3.2.1.21 (and having cellobiase activity). Further investigation of the possible substrate specificity and transglycosylation activity of the NBG will be needed in assessing its applicability in other types of biotechnical applications.
  • Leppänen, Carolina (Helsingin yliopisto, 2020)
    Tutkielman aiheena on tarkastella kahden fiktiivisen henkilöhahmon rakentumista semioottis-kognitiivisena prosessina sekä lukijan kiintymyssuhdetta henkilöhahmoihin. Tutkimuksen kohteena on kaksi Neil Gaimanin fantasiakirjaa: Coraline ja The Graveyard Book sekä erityisesti teosten päähenkilöt. Pyrin osoittamaan, että henkilöhahmojen rakentuminen on prosessi, joka yhdistää tekstin lingvistiset elementit ja lukijan kognitiiviset mielentoiminnot. Lähestymistavassani hyödynnän Jonathan Culpeperin näkemystä henkilöhahmojen pohjimmaisesta dualismista sekä tulkinnan kaksisuuntaisuudesta. Pyrin myös havainnollistamaan potentiaalisia syitä sille, miten ja miksi lukijan kiintymyssuhde henkilöhahmoihin rakentuu niin psykologisten kuin neurobiologisten prosessien kautta. Kiintymyssuhteen analysoinnissa hyödynnän tutkimuksia mm. peilineuronien toiminnasta, sekä tunnereaktioista. Ensimmäinen tulkintasuunta henkilöhahmon rakentumisessa ottaa huomioon, millä tavoin hahmo välittyy tekstistä lukijalle. Tarkastelun kohteina ovat sanavalinnat, fokalisaatio ja metaforinen kieli, jotka kiinnittävät lukijan huomion päähenkilöön tekstitasolla. Tämän lisäksi ne aikaansaavat lukijassa mielentoimintoja, jotka täydentävät, yhdistävät ja tulkitsevat luettua tekstiä verraten sitä aikaisempaan eksplisiittiseen ja implisiittiseen tietoon ihmisistä. Toinen tulkintasuunta ottaa huomioon, millä tavoin ja millaiseksi henkilöhahmo rakentuu ensisijaisesti lukijan aikaisemman tiedon ansiosta. Tarkastelun kohteina ovat lukijan perustavanlaatuiset ajatusmallit, joita hän tiedostamattaankin soveltaa kohdatessaan fiktiivisen henkilöhahmon. Tämän tulkintasuunnan analysoinnissa hyödynnän mm. Lisa Zunshinen katsausta mielenteoriaan (Theory of Mind). Tutkielmani osoittaa, että edellä mainitut tulkintasuunnat eivät ole ristiriidassa keskenään, vaan täydentävät toisiaan. Fiktiivistä henkilöhahmoa ei voi mieltää ainoastaan lingvististen elementtien summaksi tai lukijan kognition luomaksi itsenäiseksi kokonaisuudeksi, sillä tekstin ja mielen aikaansaamat prosessit ovat hyvin tiiviisti sidoksissa toisiinsa. Tutkielmani osoittaa myös, että lukijan kiintymyssuhde fiktiivisiin henkilöhahmoihin on valtaosin väistämätöntä. Kiintymyssuhde muodostuu automaattisten ja implisiittisten prosessien, kuten tunnereaktioiden kautta niin psykologisella kuin neurobiologisella tasolla.
  • Valkonen, Sami (Helsingfors universitet, 2014)
    Microvesicles (MVs) are lipid bilayered membranous vesicles containing functional lipids, proteins, RNA and DNA that are produced by most cells. The physiological significance of MVs has become evident, and increased MV counts and the contents of MVs are nowadays also associated with different pathophysiological phenomena. The goal of the field is to use MVs as diagnostic and therapeutic tools. To achieve this, the understanding of the mechanisms of the functions of MVs should be understood better and additionally, reliable methods for the quantification and characterization of MVs should be developed and standardized. The aim of the study was to determine differences in platelet-derived MVs produced by different activation mechanisms. The second aim was to set up and optimize a protocol based on the reaction of sulphur, phosphate and vanillin (SPV) for measuring lipid content of MVs. The third aim was to study the effect of thrombin and proteinase inhibitor PPACK to the vesiculation of platelets. Platelets were isolated from the whole blood of healthy volunteers and vesicles were produced by platelet agonists mediating thrombogenic activation (thrombin and collagen, TC), pathophysiological activation (lipopolysaccharide, LPS) and Ca-ionophore (A23187) as positive control for vesiculation. Quantification and size determination of produced MVs was done using Nanoparticle Tracking Analysis (NTA). MVs were characterized by protein content using bicinchonic acid assay (BCA) and by lipid content using SPV-reaction. MVs had great activation-dependent differences in the lipid and the protein content. Activation with Ca-ionophore produced the most MVs, but the lipid and protein content was only a fraction from (patho)physiologically induced MVs. Only TC increased vesiculation. Vesicle subpopulations had significant difference in lipid content. Thrombin and proteinase inhibitor PPACK mediated inhibition of platelet formation in all of the activations, but the effect was not statistically significant. The mechanism of inhibition was likely to be proteinase inhibitor mediated. The isolation of vesicle populations using differential centrifugation proved to isolate studied populations only partially and the quantification method with NTA was susceptible to concentrated samples. SPV protocol reacted with different intensity to different lipids. In the future, quantification and isolation methods for MVs and the subpopulations of MVs should be improved. Additionally, to understand the physiologically relevant mechanisms of platelet-derived vesicle formation, the inhibitor experiments with PPACK should be continued, because the number of replicates was too low to see significant effects due to a large donor-dependent deviation. Since MVs are heterogenous cellular multitools affecting varying (patho)physiological phenomena, optimization and standardization of methods should be continued in order to study MVs properly.
  • Väisänen, Rebekka Sini Eveliina (Helsingin yliopisto, 2019)
    Tutkielma käsittelee koodinvaihtoa historiallisessa fiktiossa. Erityisenä huomion kohteena on se, miten ja milloin muita kieliä (useimmiten Saksaa ja Ranskaa) esiintyy kolmessa englannikielisessä historiallisessa romaanissa joko koodinvaihdon tai muiden menetelmien kautta ja miten nämä vaikuttavat hahmojen karakterisointiin. Työssä tarkastellaan tekstin ominaisuuksiin stilistisen analyysin avulla. Teoreettisenä viitekehyksenä käytetään Carol Myers-Scottonin "tunnusmerkkisyyden mallia" (Markedness Model), jonka avulla analysoidaan koodinvaihdon funktiota suhteessa hahmojen välisiin valtarakenteisiin, ja Meir Sternbergin "käännösmimesistä" (translational mimesis), jota käytetään erilaisten teksissä esiintyviin kielten representaatioden luokitteluun. Tutkimuksen kohteena on kolme toisen maailmansodan aikaan sijoittuvaa kirjaa: Markus Zusakin The Book Thief (2005), Anthony Doerrin All the Light We Cannot See (2014) sekä Heather Morrisin Tattooist of Auschwitz (2018). Tutkimus osoittaa, että saksalaiset hahmot kuvataan yleisemmin negatiivisesti kuin muut hahmot. Saksankieliset koodinvaihdot liittyvät usein sotaan tai negatiivisiin tunteisiin, ja jopa The Book Thief:issä, jossa kaikki hahmot ovat saksalaisia, saksaa puhuvina esitetyt hahmot ovat useammin kovempia luonteeltaan, kun taas sympaattisina esitetyt hahmot puhuvat saksaa harvemmin. Vahvin vastakkainasettelu kansalaisuuksien välillä näkyy All the Light -kirjassa, jossa ranskalaiset hahmot ovat miellyttävämpiä, ja miellyttävänä esitetty saksalainen päähenkilö puhuu enemmän ranskaa kuin saksaa. Kirjoissa esiintyy monia erilaisia tapoja edustaa kieliä, joita hahmot puhuvat. Koodinvaihto on yleistä Book Thief sekä All the Light -kirjoissa, kun taas Tattooist-kirjassa vieraita kieliä edustetaan tyypillisesti eksplisiittisen attribuution kautta (esim. ”Hän kirosi ranskaksi.”). Kielten representaatiomenetelmät eivät ole vaikuttaneet siihen, miten kriitikot ja lukijat ovat ottaneet ne vastaan. Tähän todennäköisesti vaikuttaa se, että monikielisyys kuuluu luontevana osana historiallisen fiktion genreen, erityisesti toiseen maailmansotaan sijoittuvan fiktion kontekstissa, eikä koodinvaihto näin ollen yllätä tai häiritse lukukokemusta.