VTT Research System
Not a member yet
161399 research outputs found
Sort by
A biofluid-repellent nanograss coating enhances flow of protein solutions and preserves transparency of glass capillaries upon exposure to blood
No full textA transparent and superhydrophobic (SHB) nanograss coating makes glass capillaries repellent toward protein solutions and blood. The coating is fabricated using atomic layer deposited alumina which is converted into grass-like alumina (GLA) by hot water treatment (HWT). The resulting tubes are transparent and highly repellent towards water and protein solutions (sliding angle <6° for a concentrated albumin solution). The biofluid repellence of the coating reduces hydraulic resistances for protein-rich biofluids, including fetal bovine serum, by 0–50% with the strongest effect for the smallest tubes and lowest Reynolds numbers. This work addresses a knowledge gap where previous studies have mostly focused on pure water for the drag reduction effect. The tubes also show a promising ability to stay clean and transparent on short term exposure to blood, unlike unmodified glass or polymer controls
HTGR TRISO Fuel and Graphite Waste Management Strategies
No full textThis paper presents a review of possible high-temperature gas-cooled reactor (HTGR) fuel and graphite cycle back-end routes performed in the Euratom GEMINI 4.0 project based on previous European, International Atomicc Energy Agency, Nuclear Energy Agency, and diverse national research programs. It considers different variants of tristructural-isotropic (TRISO) fuel (enriched uranium, Pu, Th/233U fissile and fertile to fissile cycles, with oxide or oxicarbide fuel material options) for block-type cores. It identifies the remaining research and development issues. As the Finnish ONKALO® (Posiva Oy) repository is currently almost operable (i.e. operating license application submitted by Posiva), being therefore the first high-level waste disposal facility worldwide, its waste acceptance criteria are taken as a reference for the direct disposal of HTGR fuel elements. Spent fuel management for HTGRs is strongly impacted by the large graphite and coating volumes compared to the small portion of the fissile kernel. Therefore, a separation of the fuel compacts from the graphite block has been investigated. Disposal of spent fuel compacts separately from the graphite blocks is indeed expected to significantly reduce the HLW volumes. Processes for separating the TRISO particles from the compacts are also considered, as well as the packages for disposal of compacts or TRISO particles. For the direct disposal or disposal of separated compacts or particles, the corrosion leach resistance of the fuel kernels and of the TRISO coating layers has a crucial impact on the performance assessment of TRISO fuel disposal. Specific leach and corrosion tests on irradiated TRISO particles and fuel compacts are indispensable for establishing an optimized disposal concept. An ultimate step of separation can be to extract the fuel kernels from the TRISO coatings. It can be considered as a head-end step for reprocessing, the feasibility of which is examined. On the other hand, irradiated graphite management is a specific challenge for all graphite-moderated reactors due to the large associated volume, the specific contamination, and the degradation caused by neutron irradiation. Long-lived activation products, such as 14C and 36Cl, lead to the categorization of irradiated graphite as an intermediate-level waste in most countries. Therefore, treatment methods for reducing and/or stabilizing such isotopes for achieving a lower waste category, at a much lower disposal cost, are assessed. Reuse and refabricating options for irradiated graphite would be an interesting strategy toward a closed HTGR graphite cycle.</p
Investigation of the reaction kinetics of 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) with cellulose fibres
No full textIn the reaction system consisting of 3-chloro-2-hydroxypropyl- N , N , N -trimethylammonium chloride (CHPTAC), sodium hydroxide, cellulose and H2O, it is widely accepted that the low reaction yield is the result of fast alkaline hydrolysis of CHPTAC. Some inconsistencies remain unexplained by rapid hydrolysis alone, indicating the need to understand the role of the cellulose-NaOH interaction to advance beyond the current state of the art. This raises two key questions: is NaOH uptake on cellulose decisive for cationisation yield, and is all epoxide consumed by end of the cationisation? Investigations into the reactions rates were conducted in the absence and the presence of cellulose fibres by applying a novel ion-exchange high-performance liquid chromatography method and nitrogen analysis to quantify both reactant in solution and product formation. It was found that hydrolysis rates are slower in the presence of the fibre, which was attributed to sorption of reactants, particularly sodium hydroxide, onto the fibre. The bonding of CHPTAC to cellulose shows initially high reaction rates but approaches a plateau, even though 40% of the cationisation agent is still available in solution. This phenomenon is attributed to the consumption of “active” (deprotonated) cellulose sites, highlighting the need for improved understanding of the cellulose-NaOH interaction, and its influence on derivatisation reactions.</p
Crystal plasticity modelling of carbide network effects on microstructural strain localization and fracture behaviour in bainitic steels
Get PDFVarious steel microstructures contain carbides that are designed to enhance the strength of the material. In Reactor Pressure Vessel (RPV) steel, the carbides are an inherent part of the microstructure, finely distributed throughout the grains and grain boundaries. This work focuses on the investigation of the effect of carbides ranging from 80 nm to on strain and stress localization when the carbides are explicitly introduced in polycrystalline models. Two size dependent crystal plasticity finite element models are used in the investigation to evaluate their feasibility to address localization phenomena with carbide strengthened microstructures. We analysed the effects of carbides on quasi-2D Scanning Electron Microscopy (SEM) based microstructures with realistic carbide mapping, and utilized synthetic 3D computational grain-carbide microstructures to investigate spatial and shape effect of carbides. Microscale digital image correlation (uDIC) measurements show that strain localization is influenced significantly by carbide networks and carbides can promote slip in grains with low Schmid’s factor. Lastly, we demonstrated the effect of large carbides on fracture predictions using a newly developed microstructurally informed brittle fracture model, which represents a step forward compared with existing Beremin-type approaches. It was observed that carbide induced stress/strain heterogeneity alters fracture probability predictions notably
Introducing OpenTextile-NIR: Near-infrared hyperspectral imaging and photography dataset for optical identification of textiles
No full textThis dataset presents the first open-access collection of near-infrared hyperspectral imaging (NIR-HSI) data for the optical identification of textiles, with a focus on supporting research in sensor-based textile sorting and recycling. The dataset comprises hyperspectral images, RGB photographs, and detailed metadata, including fibre composition and colour, for 71 post-industrial textile samples, collected in Finland. Over 11 million spectra are included in the hyperspectral images, with more than 6 million annotated, providing a robust foundation for machine learning and data analysis. In addition, we provide a single representative NIR spectra and RGB value for each sample in order to accommodate classic spectroscopic analysis.Used garments were sourced from a partner company specializing in end-of-life textile management, with ground truth information on fibre composition obtained from suppliers. Small pieces of each garment were measured using Specim SWIR 3 hyperspectral camera and photographed with high-resolution mobile phone camera (Samsung Galaxy A52). The dataset is organized into folders containing raw and processed data, including ENVI-format hyperspectral images, RGB images, as well as CSV files with mean spectra, mean RGB values, and sample metadata. An example Python script is provided to facilitate data access and processing.Potential reuse scenarios include classification of textiles by material or colour, prediction of natural fibre content, image segmentation, algorithm development for spectral classification, and use as a reference spectral library. The dataset’s comprehensive structure and open availability address the limitations of previous research, which often relied on small or non-public datasets, and is intended to accelerate advances in optical identification technologies for textile recycling
Inorganics from kraft black liquor enable rapid oxidative crosslinking and morphology control in lignin derived hard carbons
No full textThe conventional approach to converting kraft lignin (KL) into hard carbons is to start with highly purified, low-ash KL feedstocks and then rely on slow, energy-intensive oxidative stabilization and added crosslinkers to keep melting and foaming associated thermal challenges under control. Herein, we deliberately invert this paradigm. Instead of starting with highly purified KL, we retain pulping inorganics and use them as catalytic centers for oxidative crosslinking and melt suppression of KL. Spherical KL microparticles (KL-MP) were recovered from softwood black liquor by membrane filtration and spray-drying steps, intentionally retaining inorganic sodium (Na) salts as well as organically bound Na in KL-MP, and were compared to acid-precipitated, low-ash reference KL (KL-REF). During thermo-oxidative pretreatment (250 °C, 5 °C/min) in air, KL-MP undergoes inorganic-catalyzed rapid oxidative crosslinking that converts thermoplastic lignin into a rigid network, whereas KL-REF softens, foams, and fuses. Experimental analysis identifies organically bound Na-phenoxide type species as key catalytic sites. Proton magnetic resonance thermal analysis and molecular dynamics simulations reveal strongly reduced segmental mobility and Na-driven ionic clusters acting as physical crosslinking points. After pretreatment, inorganics are removed by a washing step, and the crosslinked KL-MP is carbonized, yielding low-surface-area hard carbons that retain their initial micron size and spherical morphology. As Li-ion battery anodes, the derived hard carbon shows better electrochemical performance than carbons derived from KL-REF. Overall, the work shows how otherwise undesirable inorganic impurities can simplify thermal conversion of KL, with potential for diverse applications where particle size and shape are critical
Multivariate analysis on simulated moisture damage emission to indoor air
No full textMoisture damage in buildings is a significant source of indoor air problems, releasing e.g. volatile organic compounds (VOCs) and microbially produced VOCs (MVOCs), which can cause unpleasant odors and health symptoms. However, interpreting MVOCs as indicators of mold is challenging due to their various sources and limitations in analytical methods. The objective of this study was to identify the most critical factors influencing VOC emissions from moisture-damaged wall structures into the indoor environment via structural air leakages. The research was conducted using the VTT Indoor Air Quality (IAQ) Simulator and analyzed with Principal Component Analysis (PCA). The IAQ simulator was used to investigate the transport of airborne impurities from mold-contaminated wall structures in realistic building conditions and the systematic manipulation of key environmental parameters. The resulting dataset was subjected to multivariate analysis to identify the most influential factors contributing to IAQ degradation in moisture-damaged structures. The key conclusions revealed that material relative humidity was the most significant single factor affecting all VOC concentrations; higher humidity consistently increased emissions. Four specific ketones (2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone) were clearly identified as originating from microbial growth, with their concentrations being significantly higher in the presence of active mold growth. Pressure differentials had only a borderline effect on gypsum board emissions, while the insulation layer showed no significant impact on any of the identified VOC components. These findings underscore the critical role of relative humidity in determining indoor VOC profiles and highlight the value of multivariate methods in assessing mold-related indoor air problems.</p
Enzyme-Directed Assembly of Antiparallel Cellulose II Nanocrystals:Unraveling the Mechanism Beyond Spontaneous Crystallization
No full textHumans have long utilized cellulose II, known as regenerated cellulose, for fibers like rayon and Cupra and films like cellophane. While cellulose I, found in nature, consists of parallel molecular chains, cellulose II is characterized by the stable arrangement of molecules in an antiparallel orientation. Enzymatic synthesis of cellulose in vitro also affords cellulose II with various morphologies, from monolayer lamellae crystals to gels, but its formation mechanism remains obscure. Here, we demonstrate that cellodextrin phosphorylase (CDP) catalyzes the synthesis and orchestrates the antiparallel self-assembly of cellulose II nanocrystals, exceeding the paradigm of spontaneous crystallization. High-resolution structural analysis reveals CDP’s key role in dictating crystal size and alignment, bridging the gap between enzymatic catalysis and biodirected material architecture. Our research unveils a unique protein-templated assembly process for advanced cellulose materials, paving the way for enzyme-guided construction of next-generation functional nanostructures.</p
Collaborative Foresight: Major Research Trajectories and Future Research Agenda
No full textCollaborative foresight is increasingly recognized as an important tool for anticipating and shaping the future through engagement with diverse stakeholders. While academic interest in the topic has grown, highlighting its significance, the field remains fragmented. Literature on collaborative foresight is characterized by varying definitions, multiple theoretical foundations, and diverse methodological approaches. This study conducts a bibliometric review to structure the field of collaborative foresight studies, identifying four central research trajectories: (1) Collaboration in Technology Foresight, (2) Collaboration in Scenario Planning, (3) Open Foresight, and (4) Collaboration in Anticipatory Governance. Based on this structured analysis, we identify key research gaps, including the absence of a widely accepted definition of collaborative foresight, weak linkages to ecosystem and strategic management theories, and a lack of structured impact assessments to measure the long-term benefits of collaborative foresight. To address these gaps, we propose a research agenda emphasizing the development of robust theoretical foundations, stronger connections to strategic decision-making, and methodological improvements to enhance the practice and impact of collaborative foresight
A Review of Public Funding for Agri-Food Exports, 2020–2025
No full textThis report examines the public funding supporting Finnish food exports and internationalization from 2020 to 2025. The study maps key funding sources – including Business Finland, European structural funds, the Rural Development Fund, the European Maritime, Fisheries and Aquaculture Fund (EMFAF), and EU promotion programs – and analyzes their support in fostering food sector growth. The analysis highlights the multi-stage export pathway for food companies, from local business development to international market entry and scaling, emphasizing the complementary roles of innovation funding, regional development, and sectoral collaboration. The report focuses on two themes: export promotion and internationalization, and food tourism. Results show that 48.2 million euros in public support were granted, with the majority directed at companies and also to research and education organisations. Municipalities, city actors and non-profit organizations had a smaller share of the funding. The study also addresses the challenges of data comparability and the need for unified terminology and impact metrics. Recommendations include improving data systems, harmonizing concepts, and developing better impact assessment tools to support the ambitious national goal of doubling food exports by 2031