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Hemiboreal forests form a transitional belt between boreal and temperate forests in Eurasia, and due to long-term climate warming they could potentially expand in a northerly direction. However, carbon (C) exchange studies in this transitional forest type are scarce. In 2014–2015 we analyzed CO2 exchange in a hemiboreal mixed forest at SMEAR Estonia (Station for Measuring Ecosystem-Atmosphere Relations) using eddy covariance (EC), soil chamber technique and biometric methods. Employing two plots that differ in forest stand composition (mixed (MP) and coniferous (CP)) located within the footprint of the EC tower, we evaluated heterotrophic and total soil respiration (Rh and Rs, respectively). Measurements showed that C, nitrogen (N), and soil organic matter (SOM) contents in topsoil were significantly higher in the coniferous plot, and the total C stock until 20 cm of mineral soil was higher by a factor of two (i.e., 170.6 and 94.8 t C ha−1 for the CP and MP, respectively). Only in 2015 there was a significant difference in Rs between the plots, while Rh exhibited no detectable difference. The cumulative Rs during the growing season was similar for both plots (CP and MP) and years: 532 and 548 g m−2, respectively, in 2014; 636 and 592 g m−2, respectively, in 2015. The same applied to Rh: 418 and 430 g m−2, respectively, in 2014; 406 and 387 g m−2, respectively, in 2015. The forest as a whole was a C sink. In 2015, net ecosystem exchange (NEE) was -585.62 ± 45.16 g C m−2 yr−1 (the average and SD of two gap-filling methods: MDS and nonlinear regressions). Gross primary production (GPP), and ecosystem respiration (RE) were -1280.62 ± 53.36, and 696.00 ± 98.51 g C m−2 yr−1, respectively (the average and SD of two flux partitioning methods: nighttime data-based and daytime data-based). NEE and GPP suggested a greater similarity to temperate forests, while RE was closer to more boreal forest stands. The mean value of net ecosystem production (NEP) of both plots, estimated using forest stand biometric, litter and chamber data was similar to the annual NEE value: 6.3 and −5.9 t C ha−1 yr−1, respectively.

Estimation of soil-related carbon (C) fluxes is needed to understand the dynamics of the soil organic carbon pool, to determine changes in the carbon balance and functioning of forest ecosystems, and to support climate change policies. The objective of the study was to analyse the variation in the most dynamic soil C input (tree and understory above- and belowground litter production) and output (soil respiration) fluxes, in addition to the forest floor, understory and fine root biomass stocks, in eight different Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst) sites growing on mineral soils in Estonia. Further, the impact of soil C input and output fluxes on the soil organic carbon (SOC) pool was examined, and the net ecosystem production (NEP) of the stands was estimated. Fine root production (FRP) of the trees constituted 53% and 28% and needle litter constituted 25% and 28% of the total annual C input to the soil in the Norway spruce and Scots pine stands, respectively. The total FRP of the trees and the understory roots and rhizomes ranged from 211 to 1040 g m−2 yr−1, of which the understory comprised up to 28%. The mean annual soil respiration (Rs) rate was 5.7 ± 0.3 and 6.5 ± 0.3 Mg C ha−1 yr−1 in the pine and spruce stands, respectively, and did not differ significantly between the two groups of stands. The SOC pool of the studied stands depended significantly on both the above- and belowground C input fluxes. Tree-derived litter had the strongest effect on the SOC pool, while the Rh as the main soil C output flux showed no significant impact. The NEP ranged from 4.2 to −1.8 Mg C ha−1 yr−1 and demonstrated a strong negative correlation with stand age. The results affirm the importance of belowground as well as aboveground litter production on carbon accumulation in forest soils.

Clear-cutting is a conventional method of forest management which significantly changes carbon (C) cycling at the ecosystem level for a long time. Estimation of the interim period during which the ecosystem turns from a C source to a C sink is crucial for clarifying the environmental effects of management on forest C cycling. The current study provided new knowledge of C cycling in young pine stand and demonstrated the recovery of C sequestration of the forest ecosystem during the post harvesting period. We estimated the C balance in a 6-year-old Scots pine stand by using two different methods: carbon budgeting, for estimating annual net ecosystem production (NEP), and eddy covariance (EC), for estimating net ecosystem exchange (NEE). For C budgeting, the above- and belowground biomass production of the ecosystem, as well as the soil heterotrophic respiration efflux at the studied site was estimated. Annual NEE at the studied young forest ecosystem was 1.19 ± 0.36 t C ha−1, gross primary ecosystem production was 9.87 and total ecosystem respiration was 11.06 t C ha−1. Estimated NEE was in good accordance with the results of NEP (1.37 t C ha−1), which confirms the relevance of the C budgeting method. Increased annual woody biomass production is the main factor which induced the young Scots pine ecosystem to act as a C sink: annual C accumulation in tree biomass in a 6-year-old stand was 1.0 t C ha−1 but reached already 2.4 t C ha−1 in the following year. Assuming that the annual Rh flux is of the same magnitude in the subsequent years, the ecosystem will become a C sink already during a short period after clear-cut. Annual soil respiration (Rs) and heterotrophic soil respiration (Rh) were 6.0 and 4.2 t C ha−1, respectively and the Rh/Rs ratio was 0.70. However, at this stage also the understorey vegetation contributed essentially to NEP, making up 56% of the annual C uptake accumulated in the plants. The methane flux and the leached C flux were negligible, 0.004 and 0.015 t C ha−1 yr−1, respectively. Our results demonstrate that well regenerated young Scots pine stand on a former clear-cut area will be able to turn into a C sequestering ecosystem already before ten years after cutting.

Single-shot nanosecond laser ablation of stainless steel and copper surfaces in ambient air and liquid water environment was studied by contact broadband ultrasonics in the important laser intensity range of 6–450 GW/cm2, covering both regimes of surface phase explosion and formation of sub-critical ablative plasma via optical breakdown in the corresponding dense ablative plume. Similar dependences of ablative plasma pressure were obtained for the dry and wet ablation conditions, differing in their ultrasonic pulse amplitudes by the factor ∼5 and in their pulsewidths by the factor of 1.3 (copper) and 1.6 (steel) for the wet ablation because of the dynamic water-confinement effect. Excepting the confinement effect, these results indicate the similar conditions for pressure generation via sub-critical plasma formation both for the air and water environments, enlightening promising applications of laser ablation for liquid-assisted laser peening and generation of nanoparticles in liquids.

Ultraviolet (UV) exerts significant toxic effects on such blood components as erythrocytes and serum albumin under the influence of sunlight, during phototherapy, photodynamic therapy and pathogen reduction technology. In this study, we showed that epigallocatechin gallate (EGCG) isolated from Geranium rectum roots at concentrations of 1–20 μM protected erythrocytes against UVB induced damages, preventing ROS (reactive oxygen species) formation, lipid peroxidation (LP), reduced glutathione (GSH) and hemoglobin (Hb) oxidation. Our data on fluorescence anisotropy measurements noted that EGCG significantly increased the fluidity of the outer leaflet layer of erythrocytes membrane and induced a stiffening in the nonpolar region. We demonstrated that UVB irradiation of bovine serum albumin (BSA) induced S S disruption and SH group formation, which was prevented by EGCG in a dose-dependent manner. The analysis of radical-flavonoid interaction’s stoichiometry in the EGCG-DPPH model revealed that one EGCG molecule was consumed for reduction of two DPPH molecules. On the basis of theoretical calculation it was shown that the hydroxyl groups in positions 4′ and 5′ of the ring B could be considered as the most preferable H-atoms donators. Thus, the theoretical and experimental data showed that EGCG can be useful in protection of blood components against oxidative damages induced by UVB.

The accelerated spread of antibiotic resistance genes (ARG) in the environment occurs mainly through plasmid transfer facilitated via bacterial conjugation. To predict and efficiently counteract the problems associated with ARG transmission, it is important to estimate conjugation rates under different experimental conditions. The classical models typically used to estimate parameters for mating experiments, while pragmatic in calculating growth and plasmid transfer, often ignore processes such as the reduction in growth due to plasmid bearing costs and are non-inclusive of environmental influences like temperature effects. Here, we present a process-based numerical model taking into account the fitness cost associated with plasmid carriage and temperature dependencies in vertical and horizontal gene transfer processes. Observations from liquid culture conjugation experiments using Escherichia coli and the plasmid pB10 were used to validate our proposed model. We present a comparison between the parameters estimated using the existing and the proposed model. Uncertainties in the estimated parameters were quantified using classical and advanced Bayesian methods. For our mating experiments, we found that at temperatures between 20 and 37 °C, the plasmid bearing costs reduced the growth rates by > 35%. The temperature dependency model of conjugation showed a good fit (mean absolute percentage error < 10%) independent of the bacteria and the plasmid under study. The proposed model simultaneously estimates growth and plasmid transfer rate constants for all three strains (donor, recipient, and transconjugant). Simultaneous estimation of growth and conjugation parameters is particularly useful to estimate the spread of ARG when one of the mating partners inhibits the growth of the other, which is common in multi-species mating or when the incurred plasmid costs are situation dependent (e.g., increased plasmid cost in a mating environment) as observed in this study.

The rare earth elements (REEs) are cornerstone metals of modern society and are used in many applications. Europe is dependant on other continents for the safe supply of rare earth elements as these are to date not mined in Europe. In order to circumvent the shortage of supply, the rare earth elements recycling, especially from End-of-Life (EoL) products are imperative. This article evaluated the feasibility of Estonia as viable REEs recycling hub in Europe via an environmental, social and governance risks evaluation model. The model assessed the pros and cons of Estonia`s environmental, social and governance indicators, and concluded that Estonia is very suitable for the establishment of REEs recycling industry. The environmental indicators showed continuous improvement in environmental health. The Estonian education system is of excellent quality and has produced a highly skilled workforce over the past years. The country's economic indicators are good, management is transparent and business opportunities are diverse. The environmental, social and governance situations show that Estonia mostly meets the prerequisites for the establishment of a rare earth element recycling industry. The existence of such business will increase the quality of the labour force and economic growth in the long term.

The country`s national resources must be used sustainably, considering the environmental, social, and economic aspects. Estonia's potential reserves of phosphorite are among the largest in Europe, but its extraction has been a historically sensitive issue. The current study was focused on Estonians` perceptions about the potential extraction and processing of phosphorite in four stakeholder groups: the local community, the business sector, policymakers and environmental activists. An Environmental Social Governance (ESG)-risks based survey was conducted that examined the significant environmental, social and governance risks that stakeholders would like to know if such production exists. The results obtained reveal that environmental risks were more important and social risks were less important. In the cross-stakeholder comparison, environmental risks were most important for the local community and environmental activists, social risks were most important for the local community and less important for environmental activists, with the business sector valuing the importance of governance risks the most. Policymakers had more or less a similar assessment in all ESG categories. To address the multifaceted challenges of phosphorite uptake, the authors suggest creating a framework that will act as a guideline for policymakers in the future on phosphorite resource sustainable use.

Thinning is the main silvicultural method for improving stand growth and wood quality, however, despite the relevance and extensive use of thinning in forest management, its effect on stand carbon (C) balance is still poorly studied at the ecosystem level. The present case study estimated the two-year post-thinning effect on the C balance of a pole stand and a middle-aged Scots pine stand growing on mesotrophic sandy soils. Moderate thinning from below reduced the stand C storage by 21–24%, however, the amount of C accumulated in woody biomass, which was removed by logging, is expected to recover in both stands in the following four years. The reduced biomass of the trees contributed to the decreased annual net primary production (NPP) of the stand by 9–11%. The absolute value of net ecosystem production decreased by 0.9 and 0.7 t C ha−1 yr−1 in the pole and the middle-aged stand, respectively; still, both thinned plots maintained their C sink status. The production of the herbaceous understorey as well as the production of needles increased in the younger stand after thinning, but this could not compensate for C loss at the stand level. The effect of thinning on the production of mosses and dwarf shrubs was not expressed in either stand, probably due to the too short post-thinning period. Thinning did not significantly affect either total soil respiration or the heterotrophic respiration (Rh). However, it increased the contribution of Rh to total soil respiration, which can be attributed to decreased fine root biomass and root respiration, while the aboveground litterfall was not significantly changed after thinning. Fine root production, which accounted for the main belowground litter input, was significantly lower in both thinned plots. Moderate thinning in the pole and the middle-aged Scots pine stand did not change the ecosystem into a C source and the induced C loss will be compensated during a short post-thinning period.

Gap fraction measurements with digital a hemispherical camera were carried out in 2007–2016 in a Scots pine (Pinus sylvestris L.) stand growing on transitional Sphagnum bog in Jarvselja, Estonia. The measurements were done at the time when (1) the pines had maximum foliage, or (2) after autumn needle fall or before bud burst. Data for gap fraction calculation were extracted from camera raw files. For data recording, the sensor output signal maximum was kept according to the image brightness histogram within the interquartile range of the sensor dynamic range. A linear conversion method (LinearRatio) was used for image processing. The relative needle loss in autumn (20–30%) increased gap fraction by 0.02–0.05 at view zenith angles from 10° to 60° and decreased the mean plant area index from 1.86 to 1.68 after autumn litter fall. The measurement results were in good agreement with a theoretical gap fraction model simulation and with gap fraction estimates made from cover photos. The measurement and data processing protocol is appropriate for long-term monitoring in permanent sample plots.

High-pressure Si-XII and Si-III nanocrystalline polymorphs, as well as amorphous Si phase, appear consequently during multi-shot femtosecond-laser exposure of crystalline Si wafer surface above its spallation threshold along with permanently developing quasi-regular surface texture (ripples, microcones), residual hydrostatic stresses and subsurface damage, which are characterized by scanning and transmission electron microscopy, as well as by Raman micro-spectroscopy. The consequent yields of these structural Si phases indicate not only their spatially different appearance, but also potentially enable to track nanoscale, transient laser-induced high-pressure, high-temperature physical processes – local variation of ablation mechanism and rate, pressurization/pressure release, melting/resolidification, amorphization, annealing – versus cumulative laser exposure and the related development of the surface topography.

Estimation of the carbon (C) storages and fluxes in different forest ecosystems is essential for understanding their C sequestration ability. The net ecosystem production (NEP) and the net primary production (NPP) in five downy birch ( Betula pubescens ) stands, aged between 12 and 78 years, growing on fertile well-drained Histosols, were studied. Drainage of swamp forests is a large-scale manipulation, which causes significant shifts at the ecosystems level, altering C and nutrient cycling a great deal. Young and middle-aged downy birch stands (12–30-year-old) acted as C sink ecosystems, accumulating 1.4–3.0 t C ha −1 yr −1 . In the 38-year-old stand NEP was roughly zero; annual C budget was almost in balance. The over-matured downy birch stand (78-year-old) acted as a C source emitting 0.95 t C ha −1 yr −1 . Annual woody biomass increment of the stand was the main factor which affected the forest to act as a C accumulating system. Although the highest heterotrophic respiration (Rh) values were measured in the middle-aged stands, mean soil C emission did not differ significantly between the studied stands. Annual total soil respiration (Rs) and Rh ranged from 7.4 to 8.8 t C ha −1 and 4.7 to 6.2 t C ha −1 , respectively. Soil temperature appeared to be the dominant driver of the soil CO 2 effluxes. Temperature sensitivity (Q 10 value) of respiration rates (3.0–5.5), as well as the Rh/Rs (0.6–0.7) varied irrespective of stand age. Both the annual aboveground litter (1.5–1.9 t C ha −1 yr −1 ) and fine root litter (0.9–1.5 t C ha −1 yr −1 ) input fluxes were quite similar for the studied stands. However, the annual organic C input into the soil via above- and belowground litter was smaller than the annual Rh efflux, indicating that continuous mineralization of the peat layer reduces the soil organic C pool. The main share of the C stock in the drained swamp downy birch stands was soil C; the storage of C accumulated in the woody biomass of the trees accounted for only 5–20% of the total C storage of the ecosystem.

In this work, we studied a method of laser-induced coloration of metals, where small-scale spatially periodic structures play a key role in the process of color formation. The formation of such structures on a surface of AISI 304 stainless steel was demonstrated for the 1.06 µm fiber laser with nanosecond duration of pulses and random (elliptical) polarization. The color of the surface depends on the period, height and orientation of periodic surface structures. Adjustment of the polarization of the laser radiation or change of laser incidence angle can be used to control the orientation of the structures. The formation of markings that change their color under the different viewing angles becomes possible. The potential application of the method is metal product protection against falsification.

In this work, we studied a technology of color images formation on a surface of titanium film deposited on silver and gold substrates. The coloration takes place due to film oxidation by the action of a fiber laser with nanosecond duration of pulses. Color coordinates for main colors obtained on gold and silver surfaces were calculated. According to measured reflectance spectra the final color resulted from both interference effects in the thin oxide film and substrate optical properties. Mechanical and chemical resistance tests of formed images demonstrated a high degree of adhesion between deposited titanium film and precious metals. Therefore, the proposed technology has a strong potential for jewelry industry implementation.