Temperature affected the formation of arbuscular mycorrhizas and ectomycorrhizas in Populus angustifolia seedlings more than a mild drought

Arbuscular mycorrhizal (AM) plants and fungi associate with lower soil organic matter, higher pH, lower phosphorus and higher nitrogen than ectomycorrhizal (EM) ones. However, soil conditions correlate with climatic factors, and we suggest that temperature and humidity have also direct roles in the success of mycorrhiza types. The hypothesis here is that EM perform better at low temperatures than AM, and AM resist drought better than EM. Narrowleaf cottonwood (Populus angustifolia E. James) forms both AM and EM. We grew seedlings in soil at 14, 20 and 26 °C in factorial combinations with adequate watering and a cyclic mild drought for 4 and 7 weeks. As hypothesized, the percent of EM root tips was largest at 14 °C, while the proportional root length with AM was largest at the two higher temperatures. However, unlike expectations, drought increased EM formation slightly, while the AM colonization was lower in the dry treatment. Plant growth was reduced more by low temperature than drought. Root branching was more prominent at low temperature and root length and mass growth at higher temperatures. Soil nutrient availability did not provide a direct explanation to the results, as both soluble soil N and P were the same in 14 and 20 °C, while the change in mycorrhiza colonization took place between these temperatures. Differences in root morphology (root branching vs length) may affect the proportions of the mycorrhiza types at different temperature regimes. The most likely explanation to the differential colonization is that temperature affects AM and EM fungi in a different way. In nature, temperature and humidity regimes are tightly correlated, and temperature as such may be a stronger determinant for the success of mycorrhiza types than has been previously considered. The poorer performance of AM in low-temperature and drought conditions may reflect stress avoidance rather than stress tolerance by AM fungi.Peer reviewe

Getting Closer to Absolute Molar Masses of Technical Lignins

Determination of molecular weight parameters of native and, in particular, technical lignins are based on size exclusion chromatography (SEC) approaches. However, no matter which approach is used, either conventional SEC with a refractive index detector and calibration with standards or multi-angle light scattering (MALS) detection at 488nm, 633nm, 658nm, or 690nm, all variants can be severely erroneous. The lack of calibration standards with high structural similarity to lignin impairs the quality of the molar masses determined by conventional SEC, and the typical fluorescence of (technical) lignins renders the corresponding MALS data rather questionable. Application of MALS detection at 785nm by using an infrared laser largely overcomes those problems and allows for a reliable and reproducible determination of the molar mass distributions of all types of lignins, which has been demonstrated in this study for various and structurally different analytes, such as kraft lignins, milled-wood lignin, lignosulfonates, and biorefinery lignins. The topics of calibration, lignin fluorescence, and lignin UV absorption in connection with MALS detection are critically discussed in detail, and a reliable protocol is presented. Correction factors based on MALS measurements have been determined for commercially available calibration standards, such as pullulan and polystyrene sulfonate, so that now more reliable mass data can be obtained also if no MALS system is available and these conventional calibration standards have to be resorted to.Peer reviewe

Functionality of spruce galactoglucomannans in oil-in-water emulsions

For a sustainable food chain, the demand for plant-based, functional, and cost-effective food hydrocolloids is on a high-rise. Hemicelluloses from the renewable lignocellulosic biomass are available in abundance from side-streams of the forestry industry to fulfill this demand. Their effective valorization requires a safe, economic extraction method that can be up-scaled to an industrial scale and, simultaneously, understanding of their functionality to develop applications. In this study, an aqueous-based extraction method, pressurized hot water extraction (PHWE) of spruce saw meal was used to obtain galactoglucomannans (GGM), "spruce gum". Ethanol precipitation was performed to remove non-polysaccharide extractives such as free phenolic compounds, and the emulsion component ratio-dependent interfacial saturation capacity of the remaining purified fraction was studied to understand its functionality. GGM resulted in good to excellent emulsification and stabilization of oil-in-water emulsions and exhibited adsorption at the oil droplet interface, which depended on the amount of oil and droplet size of emulsions. The adsorbed GGM content was determined by gas chromatography after acid methanolysis, and their macromolecular characteristics were studied by size-exclusion chromatography. At GGM to oil ratios 2, 1, and 0.4, stable emulsions with predicted several months of shelf life at room temperature were achieved. The results indicated mechanisms affecting the physical stabilization and breakdown of emulsions containing spruce gum, a novel sustainable hydrocolloid. (C) 2018 Elsevier Ltd. All rights reserved.Peer reviewe

WtF-Nano : One-Pot Dewatering and Water-Free Topochemical Modification of Nanocellulose in Ionic Liquids or gamma-Valerolactone

Ionic liquids are used to dewater a suspension of birch Kraft pulp cellulose nanofibrils (CNF) and as a medium for water-free topochemical modification of the nanocellulose (a process denoted as "WtF-Nano"). Acetylation was applied as a model reaction to investigate the degree of modification and scope of effective ionic liquid structures. Little difference in reactivity was observed when water was removed, after introduction of an ionic liquid or molecular co-solvent. However, the viscoelastic properties of the CNF suspended in two ionic liquids show that the more basic, but non-dissolving ionic liquid, allows for better solvation of the CNF. Vibrio fischeri bacterial tests show that all ionic liquids in this study were harmless. Scanning electron microscopy and wide-angle X-ray scattering on regenerated samples show that the acetylated CNF is still in a fibrillar form. 1D and 2D NMR analyses, after direct dissolution in a novel ionic liquid electrolyte solution, indicate that both cellulose and residual xylan on the surface of the nanofibrils reacts to give acetate esters.Peer reviewe

Si nanoparticle interfaces in Si/SiO2 solar cell materials

Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode and photoluminescence. Two positron-trapping interface states are observed after high temperature annealing at 1100 °C. One of the states is attributed to the (SiO2/Si bulk) interface and the other to the interface between the Si nanoparticles and SiO2. A small reduction in positron trapping into these states is observed after annealing the samples in N2 atmosphere with 5% H2. Enhanced photoluminescence is also observed from the samples following this annealing step.Peer reviewe

Evaluation of a sub-kilometre NWP system in an Arctic fjord-valley system in winter

Terrain challenges the prediction of near-surface atmospheric conditions, even in kilometre-scale numerical weather prediction (NWP) models. In this study, the ALADIN-HIRLAM NWP system with 0.5 km horizontal grid spacing and an increased number of vertical levels is compared to the 2.5-km model system similar to the currently operational NWP system at the Norwegian Meteorological Institute. The impact of the increased resolution on the forecasts’ ability to represent boundary-layer processes is investigated for the period from 12 to 16 February 2018 in an Arctic fjord-valley system in the Svalbard archipelago. Model simulations are compared to a wide range of observations conducted during a field campaign. The model configuration with sub-kilometre grid spacing improves both the spatial structure and overall verification scores for the near-surface temperature and wind forecasts compared to the 2.5-km experiment. The subkilometre experiment successfully captures the wind channelling through the valley and the temperature field associated with it. In a situation of a cold-air pool development, the sub-kilometre experiment has a particularly high near-surface temperature bias at low elevations. The use of measurement campaign data, however, reveals some encouraging results, e.g. the sub-kilometre system has a more realistic vertical profile of temperature and wind speed, and the surface temperature sensitivity to the net surface energy is closer to the observations. This work demonstrates the potential of sub-kilometre NWP systems for forecasting weather in complex Arctic terrain, and also suggests that the increase in resolution needs to be accompanied with further development of other parts of the model system

A Global Meta-Analysis of Forest Bioenergy Greenhouse Gas Emission Accounting Studies

The potential greenhouse gas benefits of displacing fossil energy with biofuels are driving policy development in the absence of complete information. The potential carbon neutrality of forest biomass is a source of considerable scientific debate because of the complexity of dynamic forest ecosystems, varied feedstock types, and multiple energy production pathways. The lack of scientific consensus leaves decision makers struggling with contradicting technical advice. Analyzing previously published studies, our goal was to identify and prioritize those attributes of bioenergy greenhouse gas (GHG) emissions analysis that are most influential on length of carbon payback period. We investigated outcomes of 59 previously published forest biomass greenhouse gas emissions research studies published between 1991 and 2014. We identified attributes for each study and classified study cases by attributes. Using classification and regression tree analysis, we identified those attributes that are strong predictors of carbon payback period (e.g. the time required by the forest to recover through sequestration the carbon dioxide from biomass combusted for energy). The inclusion of wildfire dynamics proved to be the most influential in determining carbon payback period length compared to other factors such as feedstock type, baseline choice, and the incorporation of leakage calculations. Additionally, we demonstrate that evaluation criteria consistency is required to facilitate equitable comparison between projects. For carbon payback period calculations to provide operational insights to decision makers, future research should focus on creating common accounting principles for the most influential fac

Estimate of Opportunistic Prostate Specific Antigen Testing in the Finnish Randomized Study of Screening for Prostate Cancer

Purpose: Screening for prostate cancer remains controversial, although ERSPC (European Randomized Study of Screening for Prostate Cancer) showed a 21% relative reduction in prostate cancer mortality. The Finnish Randomized Study of Screening for Prostate Cancer, which is the largest component of ERSPC, demonstrated a statistically nonsignificant 16% mortality benefit in a separate analysis. The purpose of this study was to estimate the degree of contamination in the control arm of the Finnish trial. Materials and Methods: Altogether 48,295 and 31,872 men were randomized to the control and screening arms, respectively. The screening period was 1996 to 2007. The extent of prostate specific antigen testing was analyzed retrospectively using laboratory databases. The incidence of T1c prostate cancer (impalpable prostate cancer detected by elevated prostate specific antigen) was determined from the national Finnish Cancer Registry. Results: Approximately 1.4% of men had undergone prostate specific antigen testing 1 to 3 years before randomization. By the first 4, 8 and 12 years of follow-up 18.1%, 47.7% and 62.7% of men in the control arm had undergone prostate specific antigen testing at least once and in the screening arm the proportions were 69.8%, 81.1% and 85.2%, respectively. The cumulative incidence of T1c prostate cancer was 6.1% in the screening arm and 4.5% in the control arm (RR 1.21, 95% CI 1.13-1.30). Conclusions: A large proportion of men in the control arm had undergone a prostate specific antigen test during the 15-year followup. Contamination is likely to dilute differences in prostate cancer mortality between the arms in the Finnish screening trial.Peer reviewe

Sobolev spaces, fine gradients and quasicontinuity on quasiopen sets

We study different definitions of Sobolev spaces on quasiopen sets in a complete metric space equipped with a doubling measure supporting a p-Poincar\'e inequality with 1<p<\infty, and connect them to the Sobolev theory in R^n. In particular, we show that for quasiopen subsets of R^n the Newtonian functions, which are naturally defined in any metric space, coincide with the quasicontinuous representatives of the Sobolev functions studied by Kilpel\"ainen and Mal\'y in 1992. As a by-product, we establish the quasi-Lindel\"of principle of the fine topology in metric spaces and study several variants of local Newtonian and Dirichlet spaces on quasiopen sets.Comment: arXiv admin note: text overlap with arXiv:1410.516