Vytautas Magnus University

This study evaluates the effects of Al2O3 and CeO2 nanoparticles as additives to standard diesel and biodiesel fuels on the combustion and emissions characteristics of a CR diesel engine with split injection (pilot and main injections). Three nanoparticle dosing levels (50 ppm, 100 ppm, and 150 ppm) were compared with undoped standard diesel and biodiesel fuels. The results showed that the presence of both Al2O3 and CeO2 in biodiesel increased the ignition delay of the pilot fuel by about 8.0% at low load and about 3.5% at high load. The addition of both nanoparticles to diesel and biodiesel fuels had an insignificant effect on the main injection fuel’s ignition delay, MBF50 position and combustion duration. The thermal efficiency was up to 1.0% lower. Al2O3 additive in diesel had no significant effect on NOx emissions. CO emissions were higher by 4.4–7.5% in most cases. The Al2O3 additive in biodiesel reduced NOx emissions by an average of 38%, 17.1%, and 9.4% at low, medium, and high engine loads, respectively. The reduction in CO emissions averaged 15%. The addition of CeO2 nanoparticles to diesel fuel reduced NOx emissions by 22.5%, 8.5%, and 3.1% on average across the corresponding load ranges. When the engine was operated on CeO2-doped biodiesel, NOx emissions were lower by an average of 25.7%, 9.6%, and 2.5% at low, medium, and high loads, respectively. Adding CeO2 nanoparticles to diesel fuel increased CO emissions, whereas adding them to biodiesel significantly reduced CO emissions.

Abstract Once nearly eradicated from Europe, grey wolves ( Canis lupus ) have recently undergone a remarkable demographic recovery, but their long-term survival remains precarious. By analyzing 1,001 genomes, we uncover a mosaic of distinct evolutionary lineages, not a single recovering population. Northern populations exhibit Asian wolf ancestry, while southern populations preserve ancient Holocene lineages, with dog introgression varying by region. Isolated wolves from the Scandinavian, Italian, and Iberian peninsulas harbored particularly high levels of inbreeding and fixed deleterious mutations. Signatures of genome erosion were widespread across Europe, with many populations falling well short of the minimum size recommended for long-term survival. Our study reveals the complex tapestry of wolf ancestry and variation across Europe, which calls for nuanced, regional conservation plans founded in genetic monitoring.

The transition from pure to mixed-species forest stands is increasingly promoted to enhance ecosystem stability and multifunctionality. The growth conditions may influence the physical and mechanical properties of wood. This study evaluated wood density in pure and mixed stands of silver birch, Norway spruce, and Scots pine in Lithuania and analyzed its relationships with tree allometric parameters. Nine study plots representing pure (100%) and mixed (70/30%) stands were established under comparable site conditions. Wood density at breast height was assessed using resistance drilling (IML Resi PD500), and the increment core samples were analyzed with the LIGNOSTATION™ system. The mean values of wood density for silver birch differed by 11%, depending on the wood density determination method used. Differences between pure and mixed stands were insignificant and generally did not exceed 6%–10%. No consistent trend that was attributable to species mixing was identified. The combined data from pure and mixed stands indicate that the mean wood density, converted from microdrilling measurements, was highest in silver birch (546 kg m−3 ± 1.87 kg m−3), followed by Scots pine (476 kg m−3 ± 1.85 kg m−3) and Norway spruce (437 kg m−3 ± 1.66 kg m−3). Resistance drilling showed a moderate relationship with the core samples’ wood density (R2 = 0.59), supporting its suitability as a semi-nondestructive method. Diameter at breast height was the only tree parameter that was consistently significant across all predictive models. The combined model for all species explained up to 43% of wood density variation, while species-specific models had lower explanatory power. Overall, the results indicate that species mixing has a limited effect on wood density under the studied conditions and is unlikely to substantially alter wood quality in terms of wood density.

Harvesting naturally dynamic forests causes losses of habitat quality and functional connectivity. Focusing on Sweden as a case study of high-yield rotation forestry, we provide analyses supporting spatial prioritisation of protection, management and restoration of representative functional forest habitat networks. Habitat suitability index modelling of focal birdspecies was used to analyse how forest naturalness, habitat patch size and functional connectivity affect representative forest habitat networks in Sweden's five ecoregions. Habitat modelling for the least demanding bird species showed that of the mountain ecoregion 57-77% was functional, but in the other three boreal ecoregions only 8-9% were functional. For nemoral forests, the proportions of functional habitat networks were < 3%. More demanding species have even less functional habitat. We highlight the importance of the mountain ecoregion for forest biodiversity conservation, and the urgent need for landscape planning of protection, conservation management and nature restoration in Sweden.

Laser wakefield acceleration (LWFA) of electrons was investigated using quasi-3D Fourier–Bessel Particle-In-Cell (FBPIC) simulations to optimise the interplay between laser beam structure and plasma target parameters. Gaussian (G) and Bessel–Gauss (BG) beams driven by a 40 mJ, 10 fs laser pulse were compared, representing few-cycle mJ-class (10–100 mJ) laser systems, across a range of the normalised vector potentials a0 = 1.75–5.6. The results show that, for a fixed laser system with 40 mJ pulse energy and 10 fs duration, BG beams extend the effective acceleration length and improve electron energy gain by 20–27% relative to G drivers, despite variations in 0 arising from different focal geometries. The extended focal zone of BG beams mitigates diffraction losses, while ionisation injection from a 1% nitrogen admixture produces stable injection over a distance of ~ 100 μm at a0​=2.0. However, laser pulse evolution leads to an intensity drop by a factor of 2–2.5 over 300–500 μm, ultimately limiting the maximum acceleration length. These findings confirm that BG beams offer a robust pathway to enhance LWFA performance at sub-100 mJ laser energies, with direct implications for compact high-repetition-rate plasma accelerators.

Previous studies indicated that online learning environments present motivational challenges that may frustrate students’ basic psychological needs for autonomy, competence, and relatedness. Grounded in Self-Determination Theory (SDT) and Expectancy-Value Theory (EVT), this study aimed to identify distinct need frustration profiles among e-learners and to examine how motivation-related factors (task value, self-efficacy, goal orientation, self-directed learning, collaborative learning) and attentional control predict profile membership. A sample of 541 adult (Mage = 26.37, SD = 8.61) e-learners completed a survey which consisted of Basic Psychological Need Satisfaction and Frustration Scale (BPNSFS), Motivated Self-Directed Learning and Collaborative Learning Questionnaire (MSDLCL), and Attentional Control Scale. Latent profile analysis (LPA) based on the three (autonomy, competence, relatedness) need frustration indicators identified two profiles: a High Need Frustration profile (≈44%) and a Low Need Frustration profile (≈56%). Logistic regression analysis showed that learners with higher extrinsic goal orientation and attentional control were significantly more likely to belong to the high-frustration profile, whereas task value, self-efficacy, and self-directed or collaborative learning tendencies did not significantly predict profile membership.