Browsing by Subject "DEPOSITION"

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Now showing items 21-32 of 32
  • Ylinen, Vappu; Pylkkö, Päivi; Peura, Jussi; Tuomola, Essi; Valaja, Jarmo (2018)
    The effects of low-protein diets supplemented with DL-methionine (MET) and L-histidine (HIS) on growth, pelt size and pelt quality were studied in two performance trials conducted at the Kannus Research Farm Luova Ltd, Finland. Both trials were conducted with 200 blue foxes, caged male-female pairs, initial age on average 20 weeks (trial 1) and 25 weeks (trial 2). In trial 1, diets contained digestible crude protein (DCP) 24%, 20% and 16% of metabolisable energy (ME). In trial 2, diets contained DCP 20%, 16.5% and 13% of ME. In both trials, the middle protein level was fed with or without MET and the lowest protein level was fed with MET and with or without HIS. In trial 1, blue foxes showed the greatest average daily gain (ADG) in the highest protein diet. Pelt size and pelt quality were not affected. In trial 2, blue foxes showed the greatest ADG in the low-protein groups. Pelt size and pelt quality were not affected.
  • Kalmbach, Lothar; Helariutta, Yrjö Eero (2019)
    Sieve pores of the sieve plates connect neighboring sieve elements to form the conducting sieve tubes of the phloem. Sieve pores are critical for phloem function. From the 1950s onwards, when electron microscopes became increasingly available, the study of their formation had been a pillar of phloem research. More recent work on sieve elements instead has largely focused on sieve tube hydraulics, phylogeny, and eco-physiology. Additionally, advanced molecular and genetic tools available for the model species Arabidopsis thaliana helped decipher several key regulatory mechanisms of early phloem development. Yet, the downstream differentiation processes which form the conductive sieve tube are still largely unknown, and our understanding of sieve pore formation has only moderately progressed. Here, we summarize our current knowledge on sieve pore formation and present relevant recent advances in related fields such as sieve element evolution, physiology, and plasmodesmata formation.
  • Matkala, Laura; Salemaa, Maija; Bäck, Jaana (2020)
    The relationship of the community composition of forest vegetation and soil nutrients were studied near the Sokli phosphate ore deposit in northern Finland. Simultaneously, the effects of the dominant species and the age of trees, rock parent material and soil layer on these nutrients were examined. For this purpose, 16 study plots were established at different distances from the phosphate ore along four transects. Phosphate mining may take place in Sokli in the future, and the vegetation surveys and soil sampling conducted at the plots can be used as a baseline status for following the possible changes that the mining may cause in the surrounding ecosystem. The total phosphorus (P) and nitrogen (N) contents of the soil humus layer were positively related with species number and abundance of the understorey vegetation, and the correlation was slightly higher with P than N. This is interesting, as N usually has the most important growth-limiting role in boreal ecosystems. The spatial variation in the content of soil elements was high both between and within plots, emphasizing the heterogeneity of the soil. Dominant tree species and the soil layer were the most important environmental variables affecting soil nutrient content. High contents of P in the humus layer (maximum 2.60 g kg(-1)) were measured from the birch-dominated plots. As the P contents of birch leaves and leaf litter were also rather high (2.58 and 1.28 g kg(-1), respectively), this may imply that the leaf litter of birch forms an important source of P for the soil. The possible mining effects, together with climate change, can have an influence on the release of nutrients to plants, which may lead to alterations in the vegetation community composition in the study region.
  • Korhonen, Aku; Siitonen, Juha; Kotze, Johan; Immonen, Auli; Hamberg, Leena (2020)
    Urban forests are usually not intensively managed and may provide suitable environments for species threatened by production forestry. Thus, urban forests could have the potential of enhancing biodiversity both within cities and at a larger landscape scale. In this study, we investigated stand structures of boreal urban forests to assess them in terms of naturalness and biodiversity conservation potential. We sampled two types of urban spruce-dominated stands: random urban stands as representatives of average urban forests, and valuable urban stands known to host high polypore richness and assumed to represent urban biodiversity hotspots. Urban forests were compared to rural forests with different levels of naturalness. Living and dead trees and cut stumps were measured from all studied stands. Urban forests had generally diverse living tree structures with abundant large-diameter trees. Random urban forests had more dead wood (median 10.1 m(3) ha(-1)) than production forests (2.7 m(3) ha(-1)) but still considerably less than protected, former production forests (53.9 m(3) ha(-1)) or semi-natural forests (115.6 m(3) ha(-1)). On the other hand, valuable urban forests had relatively high median volume of dead wood (88.2 m(3) ha(-1)). We conclude that the combination of diverse stand composition and the presence of old-growth characteristics in boreal urban forests form a strong baseline from which their biodiversity value can be further developed, e.g. by leaving more fallen or cut trees to form dead wood. We propose that urban forests could become significant habitats for biodiversity conservation in the future.
  • Lyczakowski, Jan J.; Bourdon, Matthieu; Terrett, Oliver M.; Helariutta, Ykä; Wightman, Raymond; Dupree, Paul (2019)
    The woody secondary cell walls of plants are the largest repository of renewable carbon biopolymers on the planet. These walls are made principally from cellulose and hemicelluloses and are impregnated with lignin. Despite their importance as the main load bearing structure for plant growth, as well as their industrial importance as both a material and energy source, the precise arrangement of these constituents within the cell wall is not yet fully understood. We have adapted low temperature scanning electron microscopy (cryo-SEM) for imaging the nanoscale architecture of angiosperm and gymnosperm cell walls in their native hydrated state. Our work confirms that cell wall macrofibrils, cylindrical structures with a diameter exceeding 10 nm, are a common feature of the native hardwood and softwood samples. We have observed these same structures in Arabidopsis thaliana secondary cell walls, enabling macrofibrils to be compared between mutant lines that are perturbed in cellulose, hemicellulose, and lignin formation. Our analysis indicates that the macrofibrils in Arabidopsis cell walls are dependent upon the proper biosynthesis, or composed, of cellulose, xylan, and lignin. This study establishes that cryo-SEM is a useful additional approach for investigating the native nanoscale architecture and composition of hardwood and softwood secondary cell walls and demonstrates the applicability of Arabidopsis genetic resources to relate fibril structure with wall composition and biosynthesis.
  • Liu, Jian; Muinos, Henrique Vazquez; Nordlund, Kai; Djurabekova, Flyura (2019)
    In spite of the versatility of electronic properties of graphene, its fragility and low resistance to damage and external deformations reduce the practical value of this material for many applications. Coating of graphene with a thin layer of hard amorphous carbon is considered as a viable solution to protect the 2D material against accidental scratches and other external damaging impacts. In this study, we investigate the relationship between the deposition condition and quality of diamond-like-carbon (DLC) on top of multilayer graphene by means of molecular dynamics simulations. Deposition of carbon atoms with 70 eV incident energy at 100 K resulted in the highest content of sp(3)-bonded C atoms. An increase of the number of dangling bonds at the interface between the top graphene layer and the DLC film indicates that decrease of the incident energy reduces the adhesion quality of DLC thin film on graphene. Analysis of radial distribution function indicates that sp(3) hybridized carbon atoms tend to grow near already existing sp(3) -atoms. This explains why the quality of the DLC structures grown on graphene have generally a lower content of sp(3) C atoms compared to those grown directly on diamond. Ring analysis further shows that a DLC structure grown on the sp(2) -rich structures like graphene contains a higher fraction of disordered ring structures.
  • Majtyka, Anna; Nowak, Anna; Marchand, Benoit; Chrobak, Dariusz; Ritala, Mikko; Räisänen, Jyrki; Nowak, Roman (2016)
    The present paper pertains to mechanical properties and structure of nanocrystalline multiferroic BeFiO(3) (BFO) thin films, grown by atomic layer deposition (ALD) on the Si/SiO2/Pt substrate. The usage of sharp-tip-nanoindentation and multiple techniques of structure examination, namely, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectrometry, enabled us to detect changes in elastic properties (95 GPa
  • Fu, Yueyun; Xue, Mo; Cai, Runlong; Kangasluoma, Juha; Jiang, Jingkun (2019)
    Core sampling method (extracting a portion of a flow from the core of the flow) will reduce diffusional losses of highly diffusive species (e.g., aerosol nanoparticles, ions, and gases) when transporting them through a sampling tube. Revealing parameters governing the sampling efficiency of a core sampling system, eta(sam), helps to design the apparatus and to optimize its performance. In this study, we report an analytical solution for quantifying the eta(sam) by solving the convection diffusion equation of laminar flow field. The analytical results were experimentally evaluated using 1-5nm tungsten oxide nanoparticles. eta(sam) is governed by a dimensionless loss parameter and the transport-to-sample flow ratio. Theoretically predicted values for eta(sam) agree with experimental results, e.g., the relative deviation is within 5% when the value for the loss parameter is less than 0.1. The core sampling method is recommended to work at the loss parameter less than 0.1 such that eta(sam) is equal or close to the maximum value of unity and is also insensitive to variations in sampling conditions. In this study, how to apply the findings in designing and optimizing a core sampling system was discussed. A core sampling apparatus was then designed and experimentally evaluated. Its sampling efficiency was shown to be significantly higher than those of a tee, a cross fitting, and a Y fitting when the same sampling conditions were used.Copyright (c) 2019 American Association for Aerosol Research
  • Rantala, Marttiina V.; Meyer-Jacob, Carsten; Kivila, E. Henriikka; Luoto, Tomi P.; Ojala, Antti. E. K.; Smol, John P.; Nevalainen, Liisa (2021)
    Global environmental change alters the production, terrestrial export, and photodegradation of organic carbon in northern lakes. Sedimentary biogeochemical records can provide a unique means to understand the nature of these changes over long time scales, where observational data fall short. We deployed in situ experiments on two shallow subarctic lakes with contrasting light regimes; a clear tundra lake and a dark woodland lake, to first investigate the photochemical transformation of carbon and nitrogen elemental (C/N ratio) and isotope (delta C-13, delta N-15) composition in lake water particulate organic matter (POM) for downcore inferences. We then explored elemental, isotopic, and spectral (inferred lake water total organic carbon [TOC] and sediment chlorophyll a [CHLa]) fingerprints in the lake sediments to trace changes in aquatic production, terrestrial inputs and photodegradation before and after profound human impacts on the global carbon cycle prompted by industrialization. POM pool in both lakes displayed tentative evidence of UV photoreactivity, reflected as increasing delta C-13 and decreasing C/N values. Through time, the tundra lake sediments traced subtle shifts in primary production, while the woodland lake carried signals of changing terrestrial contributions, indicating shifts in terrestrial carbon export but possibly also photodegradation rates. Under global human impact, both lakes irrespective of their distinct carbon regimes displayed evidence of increased productivity but no conspicuous signs of increased terrestrial influence. Overall, sediment biogeochemistry can integrate a wealth of information on carbon regulation in northern lakes, while our results also point to the importance of considering the entire spectrum of photobiogeochemical fingerprints in sedimentary studies.
  • Paatero, Jussi; Salminen-Paatero, Susanna (2020)
    Following the atmospheric nuclear tests in the '50s and early '60s radioecological research on the (sub)arctic food chain lichen-reindeer/caribou-man was initiated in Finland among other northern countries. The enrichment of radionuclides in this food chain can lead to exceptionally high body burdens among the indigenous Sami and Inuit populations consuming large quantities of the meat and edible organs of reindeer and caribou. In Finland, first fission and activation products and natural radionuclides were studied but in the early 1970s' the investigations concerning transuranium elements were started. These studies have continued to the present as also the effects of the Chernobyl accident on the existence of neptunium, plutonium, americium and curium isotopes in the environment of northern Finland have been investigated. In addition to radioactivity measure-ments detailed dietary surveys were performed among the reindeer herders and other Sami persons to assess the human intake of radionuclides by ingestion. The main aim of this literature review is to summarize the obtained data concerning transuranium elements in the food chain lichen-reindeer-man in northern Finland but also some supporting data is included.
  • Korhonen, Aku; Penttilä, Reijo; Siitonen, Juha; Miettinen, Otto; Immonen, Auli; Hamberg, Leena (2021)
    Urban forests are often remnants of former larger forested areas, and traditionally considered as degraded habitats due to negative effects of urbanization. However, recent studies have shown that urban forests managed for recreational purposes can be structurally close to natural forests and may provide habitat features, such as dead wood, that are scarce in intensively managed forest landscapes. In this study, we assessed how urbanization affects polypore species richness and the number of red-listed polypore species in forest stands, and the occurrences of polypore species on individual units of dead wood. Spruce-inhabiting polypore assemblages and their associations to urbanization, local habitat connectivity and dead-wood abundance were investigated in southern Finland. The effects of urbanization on polypore species richness and individual species were largely negligible when other environmental variability was accounted for. Several red-listed polypore species were found in deadwood hotspots of urban forests, though urbanization had a marginally significant negative effect on their richness. The main driver of total species richness was dead-wood abundance while the number of red-listed species was also strongly dependent on local habitat connectivity, implying that a high degree of fragmentation can decrease their occurrence in urban forests. We conclude that the highest potential for providing habitats for threatened species in the urban context lies in large peri-urban recreational forests which have been preserved for recreational purposes around many cities. On the other hand, overall polypore diversity can be increased simply by increasing dead-wood abundance, irrespective of landscape context.