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The sustainability of biomass supply chains is a topic of significant debate, given its importance in the emerging bioeconomic context. This study aims to identify the criteria perceived to have the highest preference when evaluating the sustainability of biomass supply chains. The data includes the assessments of 122 international experts providing their evaluations through a questionnaire distributed between November 2019 and February 2020. The questionnaire presents pairwise comparisons of 12 sustainability sub-criteria organised into economic, social, and environmental categories. The results are analysed using the analytic hierarchy process (AHP) in combination with kernel methods to identify consensus regions in the experts' assessments. The responses showed that a large majority of experts belong to two distinct priority groups: an environmental oriented group (N = 78) and an economic oriented group (N = 21). The environmental-priority provided average weights of 22% to economic criteria, 22% to social criteria, and 56% to environmental criteria (highest priority); whereas the economic-priority group of experts assigned weights of 64% to economic criteria (highest priority), 13% to social criteria, and 23% to environmental criteria. Variations in the priorities were explained by the experts' contextual factors and backgrounds. In both groups, however, there was a consensus to prioritize the reduction of greenhouse gas emissions among environmental criteria, and revitalization of rural areas among social criteria. The results and methods proposed have broad applications in policy making, particularly in the comprehensive assessment of biomass feedstocks and supply chains, providing valuable insights for sustainable decision-making. • 122 experts from 23 countries assess sustainability criteria for biomass. • AHP ranks and weights are applied. • Two distinct groups arise with priorities: environmental vs economic. • Background and country partly explain the differences. • Social related attributes get lowest priority. [ABSTRACT FROM AUTHOR]

Summary Successful anti-viral response requires the sustained activation and expansion of CD8 + T cells for periods that far exceed the time limit of physical T cell interaction with antigen-presenting cells (APCs). The expanding CD8 + T cell pool generates the effector and memory cell populations that provide viral clearance and long-term immunity, respectively. Here, we demonstrate that 3BP2 is recruited in cytoplasmic microclusters and nucleates a signaling complex that facilitates MHC:peptide-independent activation of signaling pathways downstream of the TCR. We show that induction of the adaptor molecule 3BP2 is a sensor of TCR signal strength and is critical for sustaining CD8 + T cell proliferation and regulating effector and memory differentiation. [ABSTRACT FROM AUTHOR]

Three dimensional incompressible steady flows were investigated from a kinematical perspective. It is shown that their geometry, as defined by their streamline curvature, is directly related to the C u r l of the associated unit tangent vector t . This relationship reveals that both the complex-lamellar and the continuity flow conditions impose geometrical constraints. These simplify flow analysis considerably, enabling a pure geometric representation of the underlying physics. Specifically, rather than using the traditional physical variables of vorticity, ∇ × v and divergence ∇ ⋅ v , for the flow description, the geometric related variables ∇ × t and ∇ ⋅ t , representing the streamline curvature K S and the mean curvature of the normal congruence H n c , respectively, were considered. The systematic implementation of these mathematical findings leads to the appearance of an interesting equation for the flow velocity, as a function of H n c . Based on this, the concept of “Geometric Lensing” has been introduced. According to this concept, the normal congruence spreads or focuses the flow streamlines through its curvature, thus altering their density and ultimately flow velocity. Geometric Lensing transforms the physical problem of finding the velocity distribution to a purely geometrical one and provides an intuitive explanation of the relieving effect that three dimensional flows exhibit. Finally, the inherent relationship between physical and geometric quantities of irrotational flows is explored. The Geometric Potential Theory, originally developed for planar flows, has been extended in three dimensions. The theoretical findings could provide useful post-processing tools for both experimentalists and CFD engineers, as well as for researchers interested in scientific visualization. [ABSTRACT FROM AUTHOR]

Poplars ( Populus spp.) and Willows ( Salix spp.) are predominantly grown in plantations on arable land in southern and central parts of Sweden to produce biomass for energy and other purposes. The present study aims at characterizing their present situation with special emphasis on the current extension of the cultivation, expected yield levels as well as on their effects on soil and water. The data sources combine own measurements with existing data, trials and records from previous studies. The results show that poplar and willow currently entail 1322 and 9830 ha in Sweden, respectively, being distributed in similar areas in central and south parts of the country, with an average plantation size of 2.59 and 3.87 ha. Productivity varies depending on the measurement methods, being 6.90 and 7.7 Mg ha −1 year −1 for poplar and willow, respectively, when estimating standing biomass based on small plots but being about half this value when based on harvesting records from commercial experience. Concerning the impact on groundwater quality, poplar plantations presented higher values of NO 3 -N and lower values of PO 4 -P than willow. These differences were consistent along seasons in case of NO 3 -N, and were only observed in autumn in the case of PO 4 -P. The results showed no differences between the plantations systems concerning the organic carbon on soil, although in the subsoil (>40 cm) there were slight higher values in case of willow plantations. [ABSTRACT FROM AUTHOR]

There is currently limited experience on the introduction of new commercial crops as a source of raw material for energy uses. The present paper analyses the introduction and development of commercial willow plantations in Sweden during the period 1986-2005. A general framework is constructed in order to identify all the factors and interrelations that can describe the introduction and expansion of willow as an alternative crop for the production of raw material for energy. The factors are identified and analysed based on a broad database of information from commercial plantations, covering almost all existing plantations, and on documents referring to existing academic literature or official reports. The analysis provides with lessons that can be useful for the introduction of new energy crops in other countries and shows the possible contradictions in policy applications. The analysis confirms that stable policies and long-term contracts reduce the uncertainties associated with the cultivation. The results of this study can be of value for other countries aiming at the introduction of new crops for bioenergy. [ABSTRACT FROM AUTHOR]

Abstract: We consider an unreliable single server retrial queue with batch arrivals, accepting two types of customers, say ordinary and transit. In addition, there is a fixed number of recurrent customers in a retrial box. Ordinary and transit customers arrive in batches according to a compound Poisson process while in addition, each individual customer is subject to control admission policy upon arrival. Admitted ordinary and transit customers who find upon arrival the server unavailable, join a queue and the retrial box respectively. Upon a service completion, recurrent customers always return in retrial box while ordinary and transit leave the system. The server is subject to a hybrid failure recovery discipline. This discipline combines both the preemptive repeat and the preemptive resume disciplines according to the type of the interrupted customer. For such a system we investigate the stability conditions and the joint queue length distribution in steady state, while operating characteristics and numerical results are also presented. Reliability analysis is investigated while a stochastic decomposition result is also proved. [Copyright &y& Elsevier]

Abstract: A retrial queue accepting two types of positive customers and negative arrivals, mixed priorities, unreliable server and multiple vacations is considered. In case of blocking the first type customers can be queued whereas the second type customers leave the system and try their luck again after a random time period. When a first type customer arrives during the service of a second type customer, he either pushes the customer in service in orbit (preemptive) or he joins the queue waiting to be served (non-preemptive). Moreover negative arrivals eliminate the customer in service and cause server’s abnormal breakdown, while in addition normal breakdowns may also occur. In both cases the server is sent immediately for repair. When, upon a service or repair completion, the server finds no first type customers waiting in queue remains idle and activates a timer. If timer expires before an arrival of a positive customer the server departs for multiple vacations. For such a system the stability conditions and the system state probabilities are investigated both in a transient and in a steady state. A stochastic decomposition result is also presented. Interesting applications are also discussed. Numerical results are finally obtained and used to investigate system performance. [Copyright &y& Elsevier]

Abstract: Rotation periods control not only the above-ground growth but also the assimilate transfer to the root systems in Short Rotation Coppice (SRC). Since assimilates are needed for the nutrient supply of associated mycorrhizal fungi, their control by rotation period length seems most probable. One poplar (Populus nigra × maximowiczii cv. Max 4) and one willow clone (Salix viminalis clone 78–101) cultivated as SRC were investigated on their ectomycorrhiza formation in response to 15 years of continuous different rotation periods (three and six years) at the same test site in Northern Germany. On the poplar clone the frequency of ectomycorrhizae was significantly lower in 6-year than in 3-year rotation. On the willow clone frequency of ectomycorrhizae was not significantly affected, but the portion of dead fine roots was significantly higher in the 6-year than in the 3-year rotation in autumn. In both rotation systems, the frequency of ectomycorrhizal (EM) colonisation was significantly higher in autumn than in spring. Five EM morphotypes were found on the poplar and seven on the willow clone. EM morphotypes which were common on both clones were formed with two fungal partners of the Pezizales (Geopora cervina, Tuber rufum), one of the Agaricales (Laccaria sp.) and one of the Thelephorales (Thelephoraceae). In spring G. cervina constituted the largest part of all observed EM morphotypes on P. nigra × maximowiczii and S. viminalis. The results indicated a selective promotion of EM formation of some Pezizales (Tuber and Peziza spp.) and some Agaricales (Laccaria spp.) due to shorter rotations, and a selective promotion of other Agaricales (Inocybe sp.) and Boletales (Scleroderma spp.) due to longer rotations. This might allow selective manipulation of the mycorrhizal diversity by the selection of the rotation system. A future challenge will be to select which mycorrhizal diversity might be more advantageous for the vitality and biomass production of poplar and willow clones. [Copyright &y& Elsevier]

Landfill leachates usually need to be treated before discharged, and using soil–plant systems for this has gained substantial interest in Sweden and in the UK. A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix). Two willow varieties were tested and four irrigation regimes in sixteen 400-m2 plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (≤2160 kg N/ha), chloride (≤8600 kg Cl/ha) and other elements. Mean annual growth was 1.5, 9.8 and 12.6 tonnes DM/ha during years 1–3. For one of two willow varieties tested, relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied. [Copyright &y& Elsevier]

Abstract: This study assessed the effects of stand structure and fertilisation with wood ash and/or sludge on wood fuel quality of Salix viminalis. The relative proportions of bark and wood in 1-, 2- and 3-year-old shoot populations were determined. The concentrations of essential elements (N, P, K) and heavy metals (Cu, Zn, Cd, Ni) in bark and wood were used to assess the wood fuel quality in harvestable shoot biomass. Controlled field experiments were conducted on two newly harvested commercial short-rotation willow coppice fields. Five treatments were applied: sewage sludge at the maximum legally permitted amount; ash; two sludge–ash mixtures supplying the maximum and twice the maximum permitted sludge–ash amount; and a control receiving mineral nutrients only. The proportion of bark in the willow stands was decreasing with the age of the shoot population. The shoot population with few large stems, compared to that with many small stems, had a lower proportion of element-rich bark in the harvestable shoot biomass, meaning better quality of the wood fuel. Overall, wood fuel quality in terms of mineral concentrations was influenced by the age of the shoot population at harvest, stand structure, management practices (e.g. planting density, fertilisation) and site conditions (soil type, element availability). Our results imply that harvestable shoot biomass of willows grown as few large stems have better wood fuel quality, compared to harvestable shoot biomass of many small stems. Increased length of cutting cycle improves the wood fuel quality. [Copyright &y& Elsevier]

Abstract: Short-rotation willow (Salix sp.) coppice, a commercial crop grown for energy purposes, is used for phytoremediation of landfill leachate in Sweden. However, the leachate’s chemical composition can cause plant damage mainly due to high NaCl and NH4 concentrations. A pot experiment was conducted in order to quantify the growth responses of five different willow clones (“78–183”, “Jorr”, “Loden”, “Olof”, “Tora”) to irrigation with different leachate mixtures (corresponding to 240, 180, and 120mg Cll−1) and to assess the applicability of leaf length and leaf fluctuating asymmetry as stress indicators. A series of plant traits (shoot, root and leaf dry weight, leaf area, leaf length and leaf fluctuating asymmetry) were measured. The irrigation with leachate resulted in reduced relative growth rates but there were no clear differences between the different concentrations. The clones “Jorr” and “Loden” performed best in terms of differences in relative growth rate between control and leachate treatments. Leaf length appeared to be a useful stress diagnostic tool for use in situ showing a high correlation to growth, whereas fluctuating asymmetry showed no such correlation. Higher N, lower P and higher Na concentrations in plant stems treated with leachate than control plants were observed. [Copyright &y& Elsevier]

Abstract: Log yard run-off is a potential environmental risk, among other things because it creates an oxygen deficiency in receiving watercourses. This study was conducted to investigate the purification efficiency of soil–plant systems with couchgrass (Elymus repens) and willows (Salix sp.) when intensively irrigated with run-off from an open sprinkling system at a Norway spruce (Picea abies) log yard. The purification efficiency was determined both at the field scale (couchgrass) and in 68-L lysimeters (couchgrass and willows). Groundwater in the field and drainage water from the lysimeters were analysed for Total Organic Carbon (TOC), distillable phenols, total P, and total N. Retention of TOC, phenols and P occurred but no difference between couchgrass and willows was observed. The system had better purification capacity at the field scale than in the lysimeters. [Copyright &y& Elsevier]

Wet storage of timber and pulpwood produces large quantities of run-off water. A study was conducted to determine the purification efficiency of soil–plant systems for log yard run-off. Sixteen 1200-l lysimeters (1.2m deep soil columns) with clay or sand soil were planted with willow (Salix sp.) or alder (Alnus glutinosa), and irrigated with run-off from a Norway spruce (Picea abies) log yard. Drainage water was analysed for total organic carbon (TOC), phenols, total P and total N in order to determine concentrations and levels of retention. High retention of TOC, phenols and P occurred in the lysimeters, but no clear differences between willows and alder or clay and sand were identified. Lysimeters with high levels of irrigation showed greater retention than those with low levels. Soil–plant systems using willow and alder could provide an alternative for log yard run-off purification: the key requirement is to optimise irrigation rather than manipulate the plants or soils. [Copyright &y& Elsevier]

Short-rotation willow coppice is being used in several locations in Sweden as vegetation filters for wastewater treatment. An experiment was conducted in order to quantify the leaching of nitrogen and the toxic effects on the plants after application of wastewater under “worst case” conditions. Eight 1200-1 lysimeters (4 with clay and 4 with sand) were irrigated-fertilised with wastewater from dewatering of sewage sludge or with liquid fertiliser during 8 days, resulting in doses corresponding to 320 kg N ha−1. Thereafter, plants were daily irrigated with tapwater at a rate of 10 mm d−1 for 123 days. Nitrate-N leaching loads from May until October were approximately 70 kg N ha−1 for clay and 90 kg N ha−1 for sand lysimeters (not significantly different). Leaching loads of ammonium-N and organic N were low (approximately 10 kg N ha−1 for all treatments). The high nitrate-N leaching loads were mainly attributed to the high nitrogen application rate and not to the chemical composition of the fertilisers. No short-term damages to the plants caused by the application of wastewater were observed. [Copyright &y& Elsevier]

• Substantial potential for mitigating assessed impacts by strategic perennialization. • Highest mitigation potential found for accumulated SOC losses. • Priority areas for strategic perennialization scattered across EU. • Main ''hot spots'': Denmark, western UK, The Po valley in Italy, and the Danube basin. • 10–46% of current annual crops in EU within priority areas. Society faces the double challenge of increasing biomass production to meet the future demands for food, materials and bioenergy, while addressing negative impacts of current (and future) land use. In the discourse, land use change (LUC) has often been considered as negative, referring to impacts of deforestation and expansion of biomass plantations. However, strategic establishment of suitable perennial production systems in agricultural landscapes can mitigate environmental impacts of current crop production, while providing biomass for the bioeconomy. Here, we explore the potential for such "beneficial LUC" in EU28. First, we map and quantify the degree of accumulated soil organic carbon losses, soil loss by wind and water erosion, nitrogen emissions to water, and recurring floods, in ∼81.000 individual landscapes in EU28. We then estimate the effectiveness in mitigating these impacts through establishment of perennial plants, in each landscape. The results indicate that there is a substantial potential for effective impact mitigation. Depending on criteria selection, 10–46% of the land used for annual crop production in EU28 is located in landscapes that could be considered priority areas for beneficial LUC. These areas are scattered all over Europe, but there are notable "hot-spots" where priority areas are concentrated, e.g., large parts of Denmark, western UK, The Po valley in Italy, and the Danube basin. While some policy developments support beneficial LUC, implementation could benefit from attempts to realize synergies between different Sustainable Development Goals, e.g., "Zero hunger", "Clean water and sanitation", "Affordable and Clean Energy", "Climate Action", and "Life on Land". [ABSTRACT FROM AUTHOR]

Energy from biomass, including lignocellulosic crops such as willow ( Salix spp.), is expected to increase in importance in Sweden. This study assesses the average annual net energy yield and the ratio between gross energy yield and total primary energy input for well-managed current commercial willow production systems in Sweden subject to three levels of fertilization with mineral nitrogen (N): N-high, N-medium, and N-zero. The average annual net energy yields are estimated at 175, 133, and 86 GJ ha −1 yr −1 , and the (dimensionless) energy ratios are estimated at 19, 32, and 47, for N-high, N-medium, and N-zero, respectively. Thus, there is a trade-off between achieving a high net energy yield and achieving a high energy ratio. Since the total primary energy input amounts to ≤ 5% of the gross energy yield in all cases, and the amount of arable land is limited, productivity increases may be considered more important than energy efficiency improvements. Substantial improvements in energy performance can be achieved by increasing harvest levels and improving energy efficiency in ammonia production and biomass transportation. The results should be interpreted with caution since several input parameters, especially energy use in ammonia production, fuel consumption rates, and the yield response to fertilization, are associated with considerable uncertainties. [ABSTRACT FROM AUTHOR]

Poplar ( Populus spp.) species are currently not widely grown in Sweden but offer interesting options for future large-scale biomass production for bioenergy. This study assesses the average annual net energy yield and the ratio between the gross energy yield and the total primary energy input for well-managed current commercial poplar production systems in Sweden, with and without fertilization with mineral nitrogen (N). The two systems perform similarly, mainly because the yield response to fertilization is estimated to be small. The average annual net energy yields with and without fertilization are estimated at 190 and 179 GJ ha −1 yr −1 , respectively. The corresponding energy ratios are 32 and 34, i.e., the total primary energy inputs correspond to only ca. 3% of the gross energy yield, in both cases. Therefore, improving the net energy yield by increasing the harvest level may be considered the most important objective from an energy performance point of view. To do this, more research is needed in order to develop poplar clones that are better adapted to the Swedish climate and identify in which situations poplar responds well to fertilization. At the same time, by reducing the energy inputs associated with the most fuel-intensive activities (wood-chip transportation, chipping, harvesting, forwarding, and stump lifting), greenhouse gas emissions can be reduced. The results should be interpreted with caution since several parameters, especially the yield response to fertilization and fuel consumption rates, are associated with considerable uncertainties. [ABSTRACT FROM AUTHOR]

Wood biomass for energy can be largely produced in northern Europe from forest land resulting from silvicultural practices and from agricultural land in the form of fast-growing plantations. The present paper estimates and compares the current regional potentials for wood biomass production attending to these sources. The data are based on spatialized estimates from previous models, largely based on empirical records concerning forest and plantation's productivity. The results show that 8.5 Mm 3 of wood biomass can be produced annually from plantations when using 5% of the total available agricultural land, and 58.5 Mm 3 from forest lands using current estimates of forest production. However, the results also show that a strategy for wood biomass resource management should be local rather than general: wood biomass potential from fast-growing plantations was larger in 19 regions than from forest resources (10 in Denmark, 6 in Norway and 3 in Lithuania) out of the 91 regions in the area included to this study. When considered together, northern Europe presents significant potential for wood biomass production for energy uses, and each country - and even region - should develop independent policy strategies of biomass generation in order to most efficiently realize their own potential for wood-based bioenergy. [ABSTRACT FROM AUTHOR]

Short-rotation coppice (SRC) is an important source of woody biomass for bioenergy. Despite the research carried out on several aspects of SRC production, many uncertainties create barriers to farmers establishing SRC plantations. One of the key economic sources of uncertainty is harvesting methods and costs; more specifically, the performance of contemporary machine methods is reviewed. We collected data from 25 literature references, describing 166 field trials. Three harvesting systems predominate: 127 used single pass cut-and-chip harvesters, 16 used double pass cut-and-store harvesters, 22 used the cut-and-bale harvester, and one study used a cut-and-billet harvester. Mean effective material capacity (EMC) was 30 Mg fresh weight h -1 (cut-and-chip technique), 19 Mg fresh weight h -1 (cut-and-store technique) and 14 Mg fresh weight h -1 (cut-and-bale technique). However, this comparison does not consider engine power, which varies with harvesting technique; cut-and-chip harvesters are by far the most powerful (>200 kW). When limiting harvesters to a maximum engine power of 200 kW, cut-and-chip harvesters achieved the lowest EMC (5 Mg fresh weight h -1 ), but they also perform a higher degree of material processing (cutting and chipping) than cut-and-store harvesters (only cutting) or than the cut-and-bale harvester (cutting and baling). The trend in commercial machinery is towards increased engine power for cut-and-chip and cut-and-store harvesters. No trends in EMC were documented for the recently developed cut-and-bale harvesting technique, which is presently produced in one version only. Field stocking (5–157 Mg fresh weight ha -1 in the reviewed studies) has a significant effect on harvester EMC. Lower field stocking can constrain the maximum EMC achieved by the machine given that harvesting speed can only be increased to a point. While the reviewed studies did not contain sufficient harvesting cost data for a thorough analysis, harvesting costs ranged between 6 and 99 € Mg -1 fresh weight. [ABSTRACT FROM AUTHOR]