991 resultados para Atmosphere Polution
Resumo:
Global warming is assertively the greatest environmental challenge for humans of 21st century. It is primarily caused by the anthropogenic greenhouse gas (GHG) that trap heat in the atmosphere. Because of which, the GHG emission mitigation, globally, is a critical issue in the political agenda of all high-profile nations. India, like other developing countries, is facing this threat of climate change while dealing with the challenge of sustaining its rapid economic growth. India’s economy is closely connected to its natural resource base and climate sensitive sectors like water, agriculture and forestry. Due to Climate change the quality and distribution of India’s natural resources may transform and lead to adverse effects on livelihood of its people. Therefore, India is expected to face a major threat due to the projected climate change. This study proposes possible solutions for GHG emission mitigation that are specific to the power sector of India. The methods discussed here will take Indian power sector from present coal dominant ideology to a system, centered with renewable energy sources. The study further proposes a future scenario for 2050, based on the present Indian government policies and global energy technologies advancements.
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Hydrogen stratification and atmosphere mixing is a very important phenomenon in nuclear reactor containments when severe accidents are studied and simulated. Hydrogen generation, distribution and accumulation in certain parts of containment may pose a great risk to pressure increase induced by hydrogen combustion, and thus, challenge the integrity of NPP containment. The accurate prediction of hydrogen distribution is important with respect to the safety design of a NPP. Modelling methods typically used for containment analyses include both lumped parameter and field codes. The lumped parameter method is universally used in the containment codes, because its versatility, flexibility and simplicity. The lumped parameter method allows fast, full-scale simulations, where different containment geometries with relevant engineering safety features can be modelled. Lumped parameter gas stratification and mixing modelling methods are presented and discussed in this master’s thesis. Experimental research is widely used in containment analyses. The HM-2 experiment related to hydrogen stratification and mixing conducted at the THAI facility in Germany is calculated with the APROS lump parameter containment package and the APROS 6-equation thermal hydraulic model. The main purpose was to study, whether the convection term included in the momentum conservation equation of the 6-equation modelling gives some remarkable advantages compared to the simplified lumped parameter approach. Finally, a simple containment test case (high steam release to a narrow steam generator room inside a large dry containment) was calculated with both APROS models. In this case, the aim was to determine the extreme containment conditions, where the effect of convection term was supposed to be possibly high. Calculation results showed that both the APROS containment and the 6-equation model could model the hydrogen stratification in the THAI test well, if the vertical nodalisation was dense enough. However, in more complicated cases, the numerical diffusion may distort the results. Calculation of light gas stratification could be probably improved by applying the second order discretisation scheme for the modelling of gas flows. If the gas flows are relatively high, the convection term of the momentum equation is necessary to model the pressure differences between the adjacent nodes reasonably.
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The iron and steelmaking industry is among the major contributors to the anthropogenic emissions of carbon dioxide in the world. The rising levels of CO2 in the atmosphere and the global concern about the greenhouse effect and climate change have brought about considerable investigations on how to reduce the energy intensity and CO2 emissions of this industrial sector. In this thesis the problem is tackled by mathematical modeling and optimization using three different approaches. The possibility to use biomass in the integrated steel plant, particularly as an auxiliary reductant in the blast furnace, is investigated. By pre-processing the biomass its heating value and carbon content can be increased at the same time as the oxygen content is decreased. As the compression strength of the preprocessed biomass is lower than that of coke, it is not suitable for replacing a major part of the coke in the blast furnace burden. Therefore the biomass is assumed to be injected at the tuyere level of the blast furnace. Carbon capture and storage is, nowadays, mostly associated with power plants but it can also be used to reduce the CO2 emissions of an integrated steel plant. In the case of a blast furnace, the effect of CCS can be further increased by recycling the carbon dioxide stripped top gas back into the process. However, this affects the economy of the integrated steel plant, as the amount of top gases available, e.g., for power and heat production is decreased. High quality raw materials are a prerequisite for smooth blast furnace operation. High quality coal is especially needed to produce coke with sufficient properties to ensure proper gas permeability and smooth burden descent. Lower quality coals as well as natural gas, which some countries have in great volumes, can be utilized with various direct and smelting reduction processes. The DRI produced with a direct reduction process can be utilized as a feed material for blast furnace, basic oxygen furnace or electric arc furnace. The liquid hot metal from a smelting reduction process can in turn be used in basic oxygen furnace or electric arc furnace. The unit sizes and investment costs of an alternative ironmaking process are also lower than those of a blast furnace. In this study, the economy of an integrated steel plant is investigated by simulation and optimization. The studied system consists of linearly described unit processes from coke plant to steel making units, with a more detailed thermodynamical model of the blast furnace. The results from the blast furnace operation with biomass injection revealed the importance of proper pre-processing of the raw biomass as the composition of the biomass as well as the heating value and the yield are all affected by the pyrolysis temperature. As for recycling of CO2 stripped blast furnace top gas, substantial reductions in the emission rates are achieved if the stripped CO2 can be stored. However, the optimal recycling degree together with other operation conditions is heavily dependent on the cost structure of CO2 emissions and stripping/storage. The economical feasibility related to the use of DRI in the blast furnace depends on the price ratio between the DRI pellets and the BF pellets. The high amount of energy needed in the rotary hearth furnace to reduce the iron ore leads to increased CO2 emissions.
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Tämä tutkimus käsittelee yrittäjyyskasvatusta Oulun seudun ammattiopistossa. Tutki-muksen tavoitteena on selvittää koetaanko ulkoisen yrittäjyyden opettaminen tärkeäksi ja onko sen integroiminen ammattiaineisiin onnistunut. Tutkimuksessa selvitetään myös opiskelijoiden halukkuutta toimia yrittäjänä tulevaisuudessa työmarkkinoilla sekä miten OSAOn strategiaan kirjatut yrittäjyyden tavoitteet ovat toteutuneet. Tutkimuksen teoreettinen viitekehys rakentuu kahdesta keskeisestä käsitteestä: Yrittäjyyskasvatus ja ulkoinen yrittäjyys. Tutkimuksen kohdeorganisaationa oli Oulun seudun ammattiopisto ja tarkemmin 2. ja 3. vuosikurssin opiskelijat ja opetushenkilöstö. Tutkimuksen empiirinen aineisto kerättiin sähköisellä Webropol-ohjelmistolla. Otokseen kuului noin 4000 opiskelijaa ja 577 opettajaa. Tutkimus edustaa kvantitatiivista tutkimusmenetelmää. Tutkimukseen vastasi 568 opiskelijaa ja 239 opettajaa. Tutkimuksen luotettavuuden kannalta määriä voidaan pitää riittävinä. Suurin osa kysymyksistä oli väittämiä, joiden vastausvaihtoehtona käytettiin Likertin viisiportaista asteikkoa. Tutkimuksen eri osiot käsittelivät ulkoisen yrittäjyyden tärkeyttä ammatillisella toisella asteella, yrittäjyyden integroimisen onnistumista ammattiaineisiin, OSAOn ilmapiiriä yrittäjyydestä sekä opiskelijoiden halua työskennellä tulevaisuudessa yrittäjänä. Saatujen vastauksien perusteella ulkoisen yrittäjyyden opettaminen koetaan tärkeäksi ammatillisella toisella asteella. Yrittäjyyden integroimista ammatillisiin aineisiin ei voida pitää täysin onnistuneena ja tähän nousi syyksi tavoitteiden uupuminen tutkinnon perusteissa. OSAOn ilmapiiri koettiin ulkoista yrittäjyyttä tukevaksi. Opiskelijat suhtautuivat myönteisesti siihen, että he voisivat tulevaisuudessa työskennellä yrittäjänä.
Resumo:
Tässä diplomityössä selvitettiin UPM Kaukaan tehtailla esiintyviin lakisääteisiin hitsauskohteisiin liittyvää lainsäädäntöä ja lainsäädännön vaikutusta hitsaukselle. Lakisääteisiä hitsauskohteita ovat räjähdysvaaralliset tilat, painelaitteet, kemikaaliputkistot, kemikaalisäiliöt, maakaasulaitteet sekä kantavat teräsrakenteet. Diplomityössä selvitettiin lisäksi hitsauksen laadunhallintaa huomioiden korjaushitsaustyöt sekä uuden rakentaminen. Lakisääteet tuovat hitsauksen suorittamiselle usein tarkasti määritellyt velvoitteet koskien esimerkiksi dokumentointia, hitsaushenkilöstön pätevyyksiä, materiaaleja ja niin edelleen. Lakisääteet lisääntyvät jatkuvasti ja soveltamisalueet laajenevat, jolloin asioiden ylläpitäminen vaatii jatkuvaa seurantaa. Työssä luotiin ohjeistus koskien yleisesti hitsausta ja lisäksi käyttäjän ja omistajan velvoitteita koskevat ohjeet painelaitteista, maakaasulaitteista ja kemikaalilaitteista. Hitsauksen yleisohje koskee jokaista hitsaustapahtumaa korjaushitsauksesta uuden rakentamiseen. Ohje soveltuu lisäksi sopimusliitteeksi hitsaustyön tilauksissa.
Resumo:
The development of carbon capture and storage (CCS) has raised interest towards novel fluidised bed (FB) energy applications. In these applications, limestone can be utilized for S02 and/or CO2 capture. The conditions in the new applications differ from the traditional atmospheric and pressurised circulating fluidised bed (CFB) combustion conditions in which the limestone is successfully used for SO2 capture. In this work, a detailed physical single particle model with a description of the mass and energy transfer inside the particle for limestone was developed. The novelty of this model was to take into account the simultaneous reactions, changing conditions, and the effect of advection. Especially, the capability to study the cyclic behaviour of limestone on both sides of the calcination-carbonation equilibrium curve is important in the novel conditions. The significances of including advection or assuming diffusion control were studied in calcination. Especially, the effect of advection in calcination reaction in the novel combustion atmosphere was shown. The model was tested against experimental data; sulphur capture was studied in a laboratory reactor in different fluidised bed conditions. Different Conversion levels and sulphation patterns were examined in different atmospheres for one limestone type. The Conversion curves were well predicted with the model, and the mechanisms leading to the Conversion patterns were explained with the model simulations. In this work, it was also evaluated whether the transient environment has an effect on the limestone behaviour compared to the averaged conditions and in which conditions the effect is the largest. The difference between the averaged and transient conditions was notable only in the conditions which were close to the calcination-carbonation equilibrium curve. The results of this study suggest that the development of a simplified particle model requires a proper understanding of physical and chemical processes taking place in the particle during the reactions. The results of the study will be required when analysing complex limestone reaction phenomena or when developing the description of limestone behaviour in comprehensive 3D process models. In order to transfer the experimental observations to furnace conditions, the relevant mechanisms that take place need to be understood before the important ones can be selected for 3D process model. This study revealed the sulphur capture behaviour under transient oxy-fuel conditions, which is important when the oxy-fuel CFB process and process model are developed.
Resumo:
Tämän pro gradu -tutkielman tavoitteena oli esitellä ja analysoida osaami-sen johtamista sekä tuottaa käytännön suosituksia Alko Oy:n myymälöiden lähiesimiehille heidän henkilökuntansa osaamisen kehittämiseksi. Tämän lisäksi tutkimuksessa pyrittiin kerätyn aineiston avulla luomaan ymmärrys siitä, miten osaamisen johtamiset keinot vaikuttavat asiakastyytyväisyyteen. Tutkimus toteutettiin vertailevana tapaustutkimuksena ja tutkimusaineistoa kerättiin sekä kvantitatiivisella että kvalitatiivisella tutkimusmenetelmällä. Kohdeyrityksen myyjille lähetettiin kyselylomake heidän esimiestensä osaamisen johtamisen toimista, ja kyselystä saadun tiedon syventämiseksi haastateltiin kahdeksaa myymäläpäällikköä osaamisen johtamisen teemoista. Tutkimuksen perusteella pystyttiin muodostaman käsitys siitä, mistä osaa-misen johtaminen koostuu ja miten paremman ja heikomman osaamisen omaavien myymälöiden esimiesten toimet eroavat toisistaan. Vastausten perusteella saatiin myös ymmärrys niistä osa-alueista, joita kohdeyrityksen esimiesten toiminnassa pitäisi pyrkiä kehittämään. Osaamisen kehittämisen perustan muodostavat esimiehen oma esimerkki ja oppimiseen kannustava ilmapiiri. Esimies, joka onnistuu suuntaamaan henkilökuntansa oppimisen tukemaan organisaation tavoitteita, osaa henkilökohtaistaa yhtiön strategian sopimaan jokaisen toimenkuvaan. Oppimisen tukemisessa vaaditaan esimieheltä vahvaa henkilökunnan tuntemusta, tavoitteiden asettamista ja niiden toteutumisen seurantaa. Tutkimus osoitti esimiesten olevan pääsääntöisesti innostuneita työstään ja onnistuvan osaamisen suuntaamisen toimissa hyvin. Esimiehet voisivat kehittää toimintaansa ottamalla oman henkilökuntansa mukaan toiminnan suunnitteluun ja vastuuttamalla heitä myymälän toiminnan ja oman ammattitaitonsa jatkuvaan kehittämiseen.
Resumo:
The present study is made in the context of basic research within the field of caring science. The overall aim is to uncover and make joy visible as an idea in the world of caring. The core of caring has historically always been to alleviate suffering and to serve life and health in a spirit of love and mercy. This study has a comprehensive direction focusing on history of ideas and culminates in a pattern of ideas contenting joy in the world of caring. Knowledge formation is based on creating understanding, wholeness and meaning with regard to the knowledge related to a context. For that a hermeneutical approach is used throughout the study. In order to understand joy more deeply, the original idea, the essence and expression, the concept of 'joy' and the related concepts of 'glad' and 'light' are examined in etymological dictionaries and in Swedish, English and Latin dictionaries. To support the interpretation classical texts containing philosophers’ thoughts about joy are used. Joy as an idea glimpses forth and is presented in the form of seven-fold pattern of ideas. Through the meaning-nuances of synonyms a realization of joy could be discerned and anchored in the heart. The seven-fold pattern form the background and represent a guide for the hermeneutic reading of joy, as it appears in the stories about caring for the years 1900–1933. The historical sources consist of the trade magazine Svensk sjukskötersketidning, books containing stories about caring, archival materials and textbooks on nursing. The result culminates in the seven-fold pattern of ideas contenting what makes joy active as caring. The true heart's pure joy - love, joy is a proof of love. The ardent heart's deep joy - joy of living, joy inspires and generates strength. The bearing heart's radiant joy - generosity, joy is a gift to the other with the promise of help. The inviting heart's sparkling joy – communion, joy invites communion. The elated heart's exhilarated joy - integration, joy enables the human to forget his or her suffering and approach to what he or she wants to be. The atmospheric heart's solemn joy - dignifying, joy creates a mood and an atmosphere where people perceive themselves dignified. The peaceful heart's great joy - rescuing, a joy turns out when the human has received what may be requested of what is good, is eluded from what is evil and is contented with his or her living lot. It is hoped that this basic research will open up for a vision that can contribute to joys further attention in the world of caring and be articulated there.
Resumo:
We studied the basal and thyrotropin-releasing hormone (TRH) (50 nM) induced thyrotropin (TSH) release in isolated hemipituitaries of ovariectomized rats treated with near-physiological or high doses of 17-ß-estradiol benzoate (EB; sc, daily for 10 days) or with vehicle (untreated control rats, OVX). One group was sham-operated (normal control). The anterior pituitary glands were incubated in Krebs-Ringer bicarbonate medium, pH 7.4, at 37oC in an atmosphere of 95% O2/5% CO2. Medium and pituitary TSH was measured by specific RIA (NIDDK-RP-3). Ovariectomy induced a decrease (P<0.05) in basal TSH release (normal control = 44.1 ± 7.2; OVX = 14.7 ± 3.0 ng/ml) and tended to reduce TRH-stimulated TSH release (normal control = 33.0 ± 8.1; OVX = 16.6 ± 2.4 ng/ml). The lowest dose of EB (0.7 µg/100 g body weight) did not reverse this alteration, but markedly increased the pituitary TSH content (0.6 ± 0.06 µg/hemipituitary; P<0.05) above that of OVX (0.4 ± 0.03 µg/hemipituitary) and normal rats (0.46 ± 0.03 µg/hemipituitary). The intermediate EB dose (1.4 µg/100 g body weight) induced a nonsignificant tendency to a higher TSH response to TRH compared to OVX and a lower response compared to normal rats. Conversely, in the rats treated with the highest dose (14 µg/100 g body weight), serum 17-ß-estradiol was 17 times higher than normal, and the basal and TRH-stimulated TSH release, as well as the pituitary TSH content, was significantly (P<0.05) reduced compared to normal rats and tended to be even lower than the values observed for the vehicle-treated OVX group, suggesting an inhibitory effect of hyperestrogenism. In conclusion, while reinforcing the concept of a positive physiological regulatory role of estradiol on the TSH response to TRH and on the pituitary stores of the hormone, the present results suggest an inhibitory effect of high levels of estrogen on these responses
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In the latter days, human activities constantly increase greenhouse gases emissions in the atmosphere, which has a direct impact on a global climate warming. Finland as European Union member, developed national structural plan to promote renewable energy generation, pursuing the aspects of Directive 2009/28/EC and put it on the sharepoint. Finland is on a way of enhancing national security of energy supply, increasing diversity of the energy mix. There are plenty significant objectives to develop onshore and offshore wind energy generation in country for a next few decades, as well as another renewable energy sources. To predict the future changes, there are a lot of scenario methods developed and adapted to energy industry. The Master’s thesis explored “Fuzzy cognitive maps” approach in scenarios developing, which captures expert’s knowledge in a graphical manner and using these captures for a raw scenarios testing and refinement. There were prospects of Finnish wind energy development for the year of 2030 considered, with aid of FCM technique. Five positive raw scenarios were developed and three of them tested against integrated expert’s map of knowledge, using graphical simulation. The study provides robust scenarios out of the preliminary defined, as outcome, assuming the impact of results, taken after simulation. The thesis was conducted in such way, that there will be possibilities to use existing knowledge captures from expert panel, to test and deploy different sets of scenarios regarding to Finnish wind energy development.
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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.
Resumo:
Suorituskyvyn johtamista on tutkittu paljon teollisuustalouden näkökulmasta. Sen sijaan palvelutuotannon näkökulmasta katsottuna tutkimustyö on vasta aluillaan. Iso osa yritysten liiketoiminnasta muodostuu palvelujen tuottamisesta, joten palvelutuotannon merkitys on tänä päivänä varsin keskeisessä roolissa. Suorituskyvyn johtaminen tarvitsee rinnalleen kannustavia palkitsemismalleja. Oikein toteutettuna palkitseminen ohjaa strategian mukaisiin tavoitteisiin ja parantaa organisaation tuloksellisuutta. Palkitseminen tulee kuitenkin nähdä riittävän monipuolisena kokonaisuutena. Parhaimmillaan se sitouttaa, motivoi ja kannustaa työntekijöitä entistä parempiin suorituksiin. Epäonnistuessaan sillä on monia negatiivissa vaikutuksia. Se saattaa lisätä epäoikeudenmukaisuuden tunnetta, jolloin työilmapiiri heikkenee sekä poissaolot ja vaihtuvuus lisääntyvät. Tässä tutkimuksessa on keskitytty palvelutuotannon organisaation tutkimiseen. Tutkimuksessa selvitettiin, mitä tekijöitä tulee huomioida logistiikkasektorin palvelutuotannon organisaation onnistumista mitattaessa ja palkitessa. Tutkimus toteutettiin case-organisaatiossa konstruktiivista tutkimusotetta hyödyntäen. Tiedonkeruumenetelmänä käytettiin puolistrukturoituja haastatteluja. Tutkimuksessa rakennettiin suorituskykyä mittaava mallimittaristo ja suorituskykyä tukeva palkitsemismalli. Mittariston viitekehyksenä käytettiin Balanced Scorecardia. Tulosten perusteella voidaan todeta, että palvelutuotannon erityispiirteet tulee huomioida mittaristoa rakennettaessa. Asiakkaan rooli tulee palvelutuotannossa korostuneesti esiin. Lisäksi on huomioitava kohdeorganisaation omat strategiset tavoitteet. Mittaristoon tulee ottaa tulosmittareita, ennakoivia mittareita ja ympäristön muutosta selittäviä mittareita. Palkitsemismalleja tulee tutkia sekä aineellisen että aineettoman palkitsemisen näkökulmista. Aineellisessa palkitsemisessa tulee huomioida suoritukseen perustuva palkitseminen. Aineettomassa palkitsemisessa puolestaan on huomioitava yksilölliset tarpeet, jotka perustuvat henkilökohtaisiin ominaisuuksiin ja arvomaailmaan.
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Cyanobacteria are the only prokaryotic organisms performing oxygenic photosynthesis. They comprise a diverse and versatile group of organisms in aquatic and terrestrial environments. Increasing genomic and proteomic data launches wide possibilities for their employment in various biotechnical applications. For example, cyanobacteria can use solar energy to produce H2. There are three different enzymes that are directly involved in cyanobacterial H2 metabolism: nitrogenase (nif) which produces hydrogen as a byproduct in nitrogen fixation; bidirectional hydrogenase (hox) which functions both in uptake and in production of H2; and uptake hydrogenase (hup) which recycles the H2 produced by nitrogenase back for the utilization of the cell. Cyanobacterial strains from University of Helsinki Cyanobacteria Collection (UHCC), isolated from the Baltic Sea and Finnish lakes were screened for efficient H2 producers. Screening about 400 strains revealed several promising candidates producing similar amounts of H2 (during light) as the ΔhupL mutant of Anabaena PCC 7120, which is specifically engineered to produce higher amounts of H2 by the interruption of uptake hydrogenase. The optimal environmental conditions for H2 photoproduction were significantly different between various cyanobacterial strains. All suitable strains revealed during screening were N2-fixing, filamentous and heterocystous. The top ten H2 producers were characterized for the presence and activity of the enzymes involved in H2 metabolism. They all possess the genes encoding the conventional nitrogenase (nifHDK1). However, the high H2 photoproduction rates of these strains were shown not to be directly associated with the maximum capacities of highly active nitrogenase or bidirectional hydrogenase. Most of the good producers possessed a highly active uptake hydrogenase, which has been considered as an obstacle for efficient H2 production. Among the newly revealed best H2 producing strains, Calothrix 336/3 was chosen for further, detailed characterization. Comparative analysis of the structure of the nif and hup operons encoding the nitrogenase and uptake hydrogenase enzymes respectively showed minor differences between Calothrix 336/3 and other N2-fixing model cyanobacteria. Calothrix 336/3 is a filamentous, N2-fixing cyanobacterium with ellipsoidal, terminal heterocysts. A common feature of Calothrix 336/3 is that the cells readily adhere to substrates. To make use of this feature, and to additionally improve H2 photoproduction capacity of the Calothrix 336/3 strain, an immobilization technique was applied. The effects of immobilization within thin alginate films were evaluated by examining the photoproduction of H2 of immobilized Calothrix 336/3 in comparison to model strains, the Anabaena PCC 7120 and its ΔhupL mutant. In order to achieve optimal H2 photoproduction, cells were kept under nitrogen starved conditions (Ar atmosphere) to ensure the selective function of nitrogenase in reducing protons to H2. For extended H2 photoproduction, cells require CO2 for maintenance of photosynthetic activity and recovery cycles to fix N2. Application of regular H2 production and recovery cycles, Ar or air atmospheres respectively, resulted in prolongation of H2 photoproduction in both Calothrix 336/3 and the ΔhupL mutant of Anabaena PCC 7120. However, recovery cycles, consisting of air supplemented with CO2, induced a strong C/N unbalance in the ΔhupL mutant leading to a decrease in photosynthetic activity, although total H2 yield was still higher compared to the wild-type strain. My findings provide information about the diversity of cyanobacterial H2 capacities and mechanisms and provide knowledge of the possibilities of further enhancing cyanobacterial H2 production.
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In the present study, we examined the relationship between cell phenotype and cell survival of three human non-small cell lung carcinoma cell lines (A549, NCI-H596 and NCI-H520). Cells in exponential growth at various densities were incubated for 24 h at 37ºC in a 5% CO2 humidified atmosphere and then exposed to UV radiation for 1 min (256 nm, 40 W, source-to-target distance 100 cm). After two days the surviving cells were quantified by sulforhodamine ß staining and DNA fragmentation assay. The differences in UV sensitivity at 60 x 10³ cells/cm² among the cell lines were not related to the proliferative state of the cells but to the extent of intercellular contact. In contrast to A549 and NCI-H596, irradiated NCI-H520 cells presented lower DNA fragmentation and an aggregated cell culture phenotype even prior to confluence, suggesting that a contact-effect mechanism provides further protection against UV radiation.
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The competence of graduating nursing students is an important issue in health care as it is related to professional standards, patient safety and the quality of nursing care. Many changes in health care lead to increased demand with respect to nurses’ competence as well the number of nurses. The purpose of this empirical study was to i) describe the nurse competence areas of nursing students in Europe, ii) evaluate the nurse competence of graduating nursing students, iii) identify factors related to the nurse competence, and to iv) assess the congruence between graduating nursing students’ self-assessments and their mentors’ assessments of students’ nurse competence. The study was carried out in two phases: descriptive phase and evaluation phase. The descriptive phase focused on describing the nurse competence areas of nursing students in Europe with the help of a literature review (n=10 empirical studies and n=4 additional documents). Thematic analysis was used as the analysis method. In the evaluation phase, the nurse competence with particular focus on nursing skills of graduating nursing students (n=154) was assessed. In addition, factors related to the nurse competence were examined. Also, the congruence between graduating nursing students’ self-assessments and their mentors’ assessments of students’ nurse competence was evaluated by comparing graduating nursing students’ self-assessments with the assessments by their mentors (n=42) in the final clinical placement in four university hospitals. Descriptive statistics and inferential statistics were used to analyse the data. Based on the results, the nurse competence of nursing students in Europe consists of nine main competence areas: (1) professional/ethical values and practice, (2) nursing skills and interventions, (3) communication and interpersonal skills, (4) knowledge and cognitive ability, (5) assessment and improving quality in nursing, (6) professional development, (7) leadership, management and teamwork, (8) teaching and supervision, and (9) research utilization. Graduating nursing students self-assessed their nurse competence as good. However, when graduating nursing students’ nurse competence was assessed by their mentors, the results were poorer. Readiness for practice based on nurse education, pedagogical atmosphere on the ward, supervisory relationship between student and mentor and being in paid work in health care at the moment of the study were the most significant factors related to the nurse competence. Conclusions: Nurse competence can be evaluated with a scale based on self-assessment, but other evaluation methods could be used alongside to ensure that nurse competence can be completed and evaluated critically. Practical implications are presented for nurse education and nursing practice. In future, longitudinal research is needed in order to understand the development of nurse competence during nurse education and the transition process from a nursing student to a professional nurse.