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Okaspuidu ligniini astmeline depolümerisatsioon protoonse ioonse vedeliku-ensüümi integreeritud eeltöötlusega
No full textDoctoral Thesis in Engineering Sciences.Doktoritöö tehnikateaduse erialal.ABSTRACT. This doctoral thesis explores an innovative approach to sustainably valorize wood biomass. The research covers several stages: optimized lignin extraction, fractionation (separation into parts), enzymatic breakdown, and detailed structural analysis. In Paper I, the enzymatic breakdown of lignin obtained from an Estonian biorefinery was studied first. Results showed that lignin’s molecular weight (size of the molecule) and the presence of carbohydrate impurities significantly hinder enzymes from breaking it down larger lignin molecules and impurities make depolymerization more difficult. The breaking down of lignin into small molecule’s or depolymerization is important to make chemicals. Although, enzymes worked at fairly high lignin concentrations (up to 50 g/L) in an aqueous solution, they only cleaved bonds effectively at very low concentrations, highlighting the challenge posed by lignin’s complex structure. The knowledge from Papers I and II was then combined into a comprehensive lignin valorization process in Papers III and IV. A key advancement was using engineered bacterial enzymes (Obtained from METGEN Oy, Finland) called laccases to further break down the lignin extracted by the PIL solvent. The chosen protic ionic liquid enabled high lignin yield (70%) and efficient removal from biomass (87%), producing lignin with reduced molecular weight. Following lignin extraction, a subsequent fractionation separated lignin into two parts: a low molecular weight fraction with very little carbohydrate contamination (~2%) and a high molecular weight fraction with more impurities (~6%) was accomplished (Paper III). Afterwards, enzymatic treatment under alkaline conditions of lower molecular weight lignin modified the lignin structure significantly. NMR spectroscopy (including phenolic region analysis and HSQC correlation) quantified a 9.2% reduction in aliphatic hydroxyl groups and a 73.8% decrease in phenolic hydroxyl groups, indicating selective cleavage of lignin linkages. Crucially, the low molecular weight, low-carbohydrate fraction exhibited superior enzymatic susceptibility, directly demonstrating the inhibitory role of both molecular weight and carbohydrate impurities and validating the core hypothesis of this thesis (Paper IV). By demonstrating how optimized extraction and depolymerization can efficiently transform lignin into a renewable source of valuable chemicals, this work provides a scalable and sustainable pathway for lignin valorization.LÜHIKOKKUVÕTE. Käesolev doktoritöö käsitleb innovaatilist lähenemist puidubiomassi jätkusuutlikuks väärindamiseks. Uuring hõlmab mitut etappi: optimeeritud ligniini eraldamist, fraktsioneerimist, ensümaatilist lagundamist ja põhjalikku struktuurianalüüsi. Esimeses artiklis (Paper I) uuriti esmalt ensümaatilist ligniini lagundamist Eesti biorefinerii poolt saadud ligniinist. Tulemused näitasid, et ligniini molekulmass ning süsivesikute saasteained takistavad ensüümide tööd märkimisväärselt suuremad molekulid ja lisandid raskendavad depolümerisatsiooni ehk ligniini väiksemateks molekulideks lagundamist, mis on oluline keemiatööstuse seisukohast. Kuigi ensüümid töötasid suhteliselt kõrgetel ligniini kontsentratsioonidel vesilahuses, lõhkusid nad sideaineid efektiivselt vaid väga madalatel kontsentratsioonidel, rõhutades ligniini keeruka struktuuri esitatud väljakutseid. Esimese ja teise artikli (Papers I ja II) teadmised integreeriti seejärel põhjalikku ligniini väärindamise protsessi Papers III ja IV raames. Oluliseks edusammuks oli inseneritud bakteriaalsete ensüümide lakkasaaside (saadud METGEN Oy, Soome) kasutamine ligniini edasiseks lagundamiseks, mis oli ekstraheeritud PIL lahusti abil. Valitud protroopne ioonvedelik võimaldas saavutada kõrget ligniini saagist (70%) ja efektiivset biomassist eemaldamist (87%), tootes madala molekulmassiga ligniini. Pärast ligniini ekstraheerimist viidi läbi fraktsioneerimine, mis eraldas ligniini kaheks fraktsiooniks: madala molekulmassiga fraktsioon, kus süsivesikute saaste oli väga madal, ning kõrge molekulmassiga fraktsioon, kus lisandeid oli rohkem (Paper III). Seejärel toimus ensümaatilne töötlemine aluselistel tingimustel madala molekulmassiga ligniini fraktsioonil, mis põhjustas ligniini struktuuri olulisi muutusi. NMR-spektroskoopia (sh fenoolsete piirkondade analüüs ja HSQC korrelatsioon) näitas alifaatsete hüdroksüülrühmade 9,2% ja fenoolsete hüdroksüülrühmade 73,8% vähenemist, mis viitab ligniini sidemete selektiivsele lõhustumisele. Eriti madala molekulmassiga ja vähese süsivesikute saastega fraktsioon oli ensüümide mõjule oluliselt vastuvõtlikum, mis kinnitab ligniini molekulmassi ja saasteainete pärssivat rolli ning toetab selle doktoritöö põhihüpoteesi (Paper IV). Kokkuvõttes näitab käesolev töö, kuidas optimeeritud ekstraheerimine ja depolümerisatsioon võimaldavad efektiivselt muuta ligniini taastuvaks väärtuslike kemikaalide allikaks, pakkudes skaleeritavat ja jätkusuutlikku ligniini väärindamise lahendust
The effects of microalgae (Tetradesmus obliquus, Spirulina platensis and Chlorella vulgaris) on the nutritional profile of broiler meat
No full textReceived: July 5th, 2025 ; Accepted: September 26th, 2025 ; Published: October 23rd, 2025 ; Correspondence: [email protected] study investigated the effect of dietary supplementation with three edible microalgae species (Tetradesmus obliquus, Spirulina platensis, and Chlorella vulgaris) on the nutritional profile of broiler chicken meat. Ross 308 broilers were fed a standard diet enriched with 0.5% of one of the microalgae species over a 43-day fattening period. Meat samples from the breast and thigh muscles were collected on days 35 and 43 to analyse its nutritional profile. Although no statistically significant differences were observed in growth performance, several biologically differences became apparent. C. vulgaris administration was associated with an initial increase in thigh meat fat content on day 35, followed by a notable reduction by day 43, and led to higher protein and polyunsaturated fatty acid levels. However, it resulted in the highest omega-6/omega-3 ratio among the groups. S. platensis contributed to a more favorable fatty acid profile, with the lowest omega-6/omega-3 ratio and increased protein levels, particularly in breast meat. T. obliquus supplementation produced leaner meat, improved vitamin B12 content, and maintained a more balanced omega-6 to omega-3 ratio by day 43, suggesting a cumulative benefit with prolonged feeding. These findings indicate that each microalga has species-specific effects on broiler meat quality, supporting their potential use as sustainable functional feed ingredients tailored to specific nutritional goals in poultry production
Analysis of charging capacity for electric vehicles in soviet-era apartment districts from the perspective of substation power availability
No full textReceived: April 22nd, 2025 ; Accepted: June 13th, 2025 ; Published: July 10th, 2025 ; Correspondence: [email protected] article analyses the potential for electric vehicle (EV) home charging in a Sovietera apartment district powered by the Lammi substation in Tartu, Estonia. Using one year of hourly electricity consumption data from 360 apartments, the study evaluates three load management scenarios to determine how many EVs can be supported without overloading the existing transformer infrastructure. The analysis is based on a worst-case winter week, reflecting realistic household consumption patterns and typical EV charging behaviour, which does not require daily charging. Three load control strategies are compared: (1) dynamic load management limited by weekly peak load; (2) fixed nighttime charging within a capped substation load; and (3) full dynamic charging for all apartments. The results show that up to 96, 218, and 360 EVs could be supported under these respective scenarios. The findings highlight how the choice of charging strategy significantly affects infrastructure demands and demonstrate that coordinated load management can enable broader EV integration without immediate large-scale investment. The study contributes practical insight for energy planners and housing associations seeking to align smart charging systems with the technical limits of existing substations
Automated greenhouse project
No full textRakenduskõrgharidusõppe lõputöö
Tehnotroonika õppekavalKasvuhoones veega kastmine saaks olla tõhusam võrreldes praegusega. Hetkel turul
leiduvad eraisikutele müüdavad kasvuhoone automaatsed kastmissüsteemid ei võta
arvesse muutuvaid kasvutingimusi. Projekti eesmärgiks on luua automatiseeritud
kasvuhoone, mis kasutades sensoreid tuvastab kasvuhoone oleku puudujääke ja eemaldab
neid. Projekti jooksul automatiseeriti kasvuhoones kastmine, tuulutus ja valgustus.
Projekti tulemus on paigaldatav moodul kasvuhoone külge, mis juhib kasvuhoone
automaatikat. Edasiarendus võimalustena on võimalik automatiseerida küttesüsteem
külmade ilmade puhul ja päikeseenergial töötav automaatika.Watering solutions in greenhouses could be made more efficient compared to the current
methods. Currently available automatic greenhouse watering systems for civilian use do
not take the plants' changing growing conditions into account. The goal of this project is
to create an automated greenhouse that uses sensors to detect deficiencies in the
greenhouse environment and eliminate them. During the project, the greenhouse’s
watering, ventilation, and lighting systems were automated. The result of the project is an
installable module that can be attached to the greenhouse to control its automation. As
further development options, it is possible to automate the heating system for cold weather
conditions and to use solar-powered automation
Liming alone is not enough: The role of phosphorus and boron in supporting legume pasture growth
No full textReceived: June 28th, 2025 ; Accepted: October 7th, 2025 ; Published: November 6th, 2025 ; Correspondence: [email protected] fertility management is a critical factor for ensuring the persistence of the legume component in improved pastures in Mediterranean regions. To promote legume growth, the most common practices include the application of lime to correct Soil acidity and phosphate fertilizers to address phosphorus (P) deficiencies. This study examined two acidic soils and evaluated the need for P and boron (B) supplementation following liming. A factorial pot experiment (Soil type × vegetation type × fertilizer treatment) was conducted using subterranean clover (Trifolium subterraneum L.), annual ryegrass (Lolium multiflorum Lam.), and their mixture. Results revealed significantly higher dry matter yield (DMY) for the legume (18.1 g pot⁻¹) compared to the grass (5.9 g pot⁻¹), due to the legume's ability to access atmospheric nitrogen (N). Soil 2, which had higher initial P availability than Soil 1, and P fertilization both enhanced N accumulation in legume tissues, the percentage of N derived from the atmosphere (%Ndfa), and DMY. These outcomes indicate that liming alone was insufficient to increase P availability and eliminate the need for P fertilization. For instance, DMY increased from 15.0 g pot⁻¹ with liming alone to 19.4 g pot⁻¹ when P was supplemented. Additionally, B application increased N uptake and %Ndfa in the legume, with the latter rising from 48.9% in the liming-only control to 77.5% with B supplementation. These results suggest that liming, by increasing Soil pH, may reduce B bioavailability, highlighting the need for B supplementation following lime application
Võõrliikide invasiooni eduvalemid ja mõju magevee elustikule
No full textDoctoral Thesis in Applied Biology.Doktoritöö rakendusbioloogia erialal.ABSTRACT. The spread of invasive species has been forecasted to increase, particularly in freshwater ecosystems due to anthropogenic and environmental changes taking place at increasing rates. Invasive species generally adapt quickly to new environments, have high reproductive rates and can tolerate a wide range of conditions. This thesis studied three invasive species in the Narva reservoir area and found that their success is linked to dietary flexibility, behaviour, and tolerance to temperature changes.
The Amur sleeper fish (Percottus glenii) can inhabit various waterbodies, for example, we found it in a warm-water channel, a large reservoir and a small pond. The Amur sleeper demonstrated great dietary plasticity, or the ability to consume a wide range of prey items. As Amur sleeper individuals grew, their diet shifted from a benthivorous diet to a piscivorous diet. The small amphipod Gmelinoides fasciatus, which has outcompeted and displaced native gammarid Gammarus lacustris in Lake Peipsi, exhibits superior predator avoidance and shows a more pronounced behavioural response to predators than its native counterpart, increasing its survivability. Marbled crayfish (Procambarus fallax virginalis) can shift from a protein rich macroinvertebrate based diet to a macrophyte based diet, indicating great dietary plasticity. Additionally, marbled crayfish, despite being considered a warm-water species, could withstand a wide range of water temperatures ranging from 0-30 °C over an extended period at our study site.
During the implementation of invasive species management programs, it is important to consider their environmental tolerance, dietary adaptability and behavioural traits. As conditions change in our freshwater lakes and reservoirs, it is likely that invasive species will continue to be a problem, highlighting the need to understand and manage their spread to protect native freshwater ecosystems.LÜHIKOKKUVÕTE. Invasiivsed võõrliigid on sellised liigid, mis levivad uude keskkonda ning mõjutavad sealses asukohas kohalikku elurikkust, ökosüsteemi toimimist ja sotsiaalmajanduslikke väärtusi. Teatud invasiivsete liikide levik kujutab endas suurt ohtu veeökosüsteemidele, kuna veekeskkonda sisse toodud võõrliikidest vabanemine on sisuliselt võimatu. Tavapäraselt on invasiivsetele võõrliikidele omane kõrge viljakus, kiire kohanemisvõime uutes oludes ja paindlikkus keskkonnatingimuste suhtes. On prognoositud, et invasiivsete liikide levik näitab tulevikus tõusutrendi. Töö käigus uurisime kolme invasiivset võõrliiki Narva veehoidla lähistel ning proovisime välja selgitada, mis aitab neil uues keskkonnas niivõrd edukalt hakkama saada.
Kaugida unimudilat (Percottus glenii) leidsime välitööde käigus Narva veehoidlast ning selle lähedal asuvast tiigist ning soojavee kanalist. Tulemused näitasid, et Kaugida unimudil on väga laia ja paindliku toiduspektriga kalaliik, kes läbib hilisemas eas ülemineku röövtoidule. Piiratud ruumiga keskkonnas näis ta tekitavat endale võrreldes kohalike kalaliikidega unikaalse toitumisnišši, samas avatud veehoidlas toimus otsene konkurents teiste kalaliikidega. Tillukene amfipood rändvähk (Gmelinoides fasciatus) on Peipsi järvest välja tõrjunud kohaliku järve-kirpvähi (Gammarus lacustris). Laborikatsed näitasid, et rändvähk on kohalikust järve-kirpvähist parem kalade eest peituja. Samuti tajus rändvähk paremini kalade poolt eritatud ohulõhna, võimaldamaks rändvähil ohu tekkides sellele hõlpsamini reageerida. Marmorvähki (Procambarus fallax virginalis) leiti Eestis esmalt 2017 Narva veehoidlasse suubuvast Balti soojuselektrijaama kanalist. Töö tulemused näitasid, et sooja vett eelistav marmorvähk on võimeline taluma laia temperatuuride vahemikku (0-30). Invasiivsete võõrliikide ohjamisel on oluline arvestada liigispetsiifilisi erisusi, näiteks vastupidavust keskkonnatingimuste suhtes, toitmisharjumusi ja käitumislikke tunnuseid. Eesti siseveekogudes on tekkinud püsivad võõrliikide populatsioonid, mis nõrgestavad kohalike liikide käekäiku ning lihtsustavad tulevikus uute võõrliikide sissetungi. Oluline on selles valdkonnas tööd ka tulevikus jätkata, et saaksime teha kaalutletud majadamisotsuseid kohaliku elurikkuse säilitamiseks tulevastele põlvkondadele.Publication of this thesis is supported by the Estonian University of Life Sciences
Evaluating the STICS Soil-Crop Model on durum wheatchickpea intercropping system under the semi-arid conditions of Southern Tunisia
No full textReceived: March 12th, 2025 ; Accepted: July 4th, 2025 ; Published: September 2nd, 2025 ; Correspondence: [email protected] models provide critical insights for designing and assessing innovative cropping systems, particularly for improving sustainability in water-limited regions. However, accurately modeling intercropping systems particularly those involving grains and legumes continues to pose a significant challenge in agricultural research. This study focuses on the initial calibration and evaluation of the STICS soil-crop model for a durum wheat-chickpea intercropping system in Mediterranean semi-arid conditions. Field experiments were conducted during 2020–2021 and 2021–2022 cropping seasons in the Medenine region, Tunisia, with comparison between the intercropping and monoculture systems. The Model performance was evaluated using Aboveground Plant Nitrogen (AGPN) as an indicator of nitrogen uptake. The STICS model demonstrated satisfactory predictive capacity across most simulations, with efficiency (EFF) values ranging from 0.56 to 0.80. Grain yield predictions were reasonably accurate, as indicated by a normalized root mean square error (NRMSE) of ≤ 37%, particularly for durum wheat (EFF ≥ 0.55). The model effectively simulated the soil water content, achieving an efficiency (EFF) of ≥ 0.51 and an NRMSE of ≤ 25%, especially in the chickpea plots. However, the predictions of the soil nitrogen stock were less accurate in the chickpea monocultures, with efficiency values ≤ 0.38 and NRMSE ≥ 44%. The intercropping simulations showed moderate accuracy, with efficiency values up to 0.41. These findings highlight the potential complementary interactions between durum wheat and chickpeas in using nitrogen and carbon resources. This study contributes to the development of sustainable agricultural practices tailored to Mediterranean climates, supporting climate adaptation and resource efficiency
Environmental factors affecting the perceived well-being of pedestrians in the streetscape
No full textMagistritöö
Maastikuarhitektuuri õppekavalAutostumise tõttu on tänavaruumi arendatud eelkõige kui transpordikoridori, mitte olemise ruumi, mis on aga muutnud tänavad jalakäijatele ebameeldivamaks. Ometi on jalakäimine üks tervislikumaid, kättesaadavamaid ja keskkonnasõbralikumaid transpordiviise ja seda tuleb soodustada. Motivatsiooni jalgsi käia ja jalgsikäimise kogemust mõjutab aga tänavaruumi kvaliteet. Käesoleva magistritöö eesmärk on uurida, missuguseid keskkonnaelemente peavad jalakäijad enda heaolu kõige suuremateks mõjutajateks tänavaruumis ning milline on nende jaoks meeldiv tänavaruum. Magistritöö põhineb 81 intervjuul, mida on analüüsitud nii kvantitatiivsete kui kvalitatiivsete meetoditega. Tulemustest selgub, et jalakäijate heaolu mõjutab muuhulgas roheluse hulk, kõnnitee laius kui ka teised jalakäijad ning meeldivas tänavaruumis soovitakse näha rohkelt rohelust, turvalist liiklust, mugavat kõnniteekonda ja ruumilist vaheldusrikkust. Töö tulemused võivad olla sisendiks inimsõbralikuma tänavaruumi loomisele.Increasing car ownership has led to street space being developed primarily as a transport corridor, rather than a space for being, which in turn has made streets less pleasant for pedestrians. However, walking is one of the healthiest, most affordable and environmentally friendly means of transport and it should be encouraged. Yet, the motivation to walk and the experience of walking are affected by the quality of street space. The aim of this thesis is to explore what environmental elements pedestrians consider to be the most important factors contributing to their wellbeing in street spaces and their perception of a pleasant street space. The thesis is based on 81 interviews analysed using both quantitative and qualitative methods. The results indicate that pedestrians' well-being is influenced by, among other things, the amount of greenery, width of pavement and presence of other pedestrians, and that a pleasant streetscape is characterised by an abundance of greenery, safe traffic, comfortable walking conditions and spatial variation. The results of the thesis could be an input for creating a more human friendly streetscape
Biodiversity of phytoplankton (non-diatoms) as bio- indicators in assessing the water quality and trophic status of the Euphrates river between Al- Baghdadi and Al-Ramadi Cities, Western Iraq
No full textReceived: November 28th, 2024 ; Accepted: February 26th, 2025 ; Published: April 16th, 2025 ; Correspondence: [email protected] the global climate changes, especially the drought conditions that Iraq's climate has been suffering from in recent years, along with the stifling water scarcity, the current study aimed to focus on developing quantitative and qualitative tools and strategies for phytoplankton (non-diatoms) as vital indicators in order to protect ecosystems, enhance their resilience, and promote sustainability. Four sites were chosen for the most prominent cities. The main site within the river basin for the period from July 2022 to April 2023 to collect water samples and phytoplankton cells (non-diatoms). The current study showed that the water of the Euphrates River at the current study sites is warm, pH neutral, with high basicity and medium hardness, with EC, TDS and turbidity, and the BOD is high, exceeding permissible limits, with good ventilation. Cl and Na salts, nutrients as NO3, were available in normal proportions, with PO4 concentrations exceeding the permissible limits due to the river water’s impact on agricultural lands around the river basin. During the study, 137 species belonging to five main classes were identified. Chlorophyceae were dominant at a rate of 55%, followed by Cyanophyceae at a rate of 34%, then Euglenophyceae at a rate of 4%, then Pyrrophyceae at a rate of 4%, and Chrysophyceae at a rate of 1%, where the highest density was recorded. For phytoplankton cells (non-diatoms) in site 1 (Al-Baghdadi) 2,438.8 cells L-1, while the lowest density was recorded in site 4 (Al-Ramadi Dam) 1,761.2 cells L-1. The results of biodiversity indices showed that the waters of the Euphrates River have low to moderate biological diversity, little to moderate pollution, and moderate species richness, with high homogeneity in their distribution between sites. The predominant groups of species during the study period were Oscillatoria formosa, Pediastrum simplex, p. duplex, Scenedesmus alternate, S. dimorphus, S. quadricauda, S. artcuatus var. platydiscus, microporium crassior, Pediastrium boryanum, Coeloastrum microporium, Chrococcus limeticus, C. minor
Vasula
No full textPhytoplankton biomass, diversity and abundance in samples collected from Lake Vasula during the period 1928-2015