Biobased Polyurethanes from Rapeseed Oil Polyols: Structure, Mechanical and Thermal Properties

Biobased polyols were synthesized from rapeseed oil (RO) with diethanolamine (DEA), triethanolamine (TEA) and glycerol (GL) at different molar ratios. The structures of the synthesized polyols were analyzed using FTIR-ATR spectroscopy. Polyurethane (PU) networks from RO/DEA polyols and polymeric MDI showed higher tensile strength, modulus and hardness, but their elongation at break decreased, compared to the case of the PU obtained from RO/TEA and RO/GL polyols. The tensile strength and modulus of PU networks increased with increasing PU cohesion energy density (CED) and decreasing molecular weight between crosslinks M _c . From the thermogravimetric analysis and its derivative thermograms, at the first stage of destruction (below 5 % weight loss) in the air and inert atmosphere, the PU obtained from RO polyols were ranked in the following order: PU RO/GL > PU RO/TEA > PU RO/DEA, and their thermostability was higher than that of the PU based on propylene oxide.     

Evaluating the influence of nature connection and values on conservation attitudes at a tropical deforestation frontier

Inner phenomena, such as personal motivations for pursuing sustainability, may be critical levers for improving conservation outcomes. Most conservation research and policies, however, focus on external phenomena (e.g., ecological change or economic processes). We explored the factors shaping 9 conservation attitudes toward forest and wildlife protection among colonist farmers around an Amazonian deforestation frontier. Our data comprised 241 face-to-face quantitative surveys, complemented with qualitative insights from open-ended questionnaire responses and opportunistic semistructured interviews. To account for the full spectrum of possible inner motivations, we employed measures of nature connection (indicating biospheric motivation) and personal values organized around the traditionalism (traditionalist through to high openness to change) and universalism dimensions (egoistic through to altruistic motivations). We used averaged beta-binomial generalized linear models to assess the role of external factors (socioeconomic, sociodemographic, and environmental) and personal (inner) motivations on the variation in attitudes. Each attitude was modeled separately. The relative importance of each predictor was judged by the proportion of models where it appeared as significant. Proconservation views were expressed by the majority (at least 65%) of the respondents in 7 out of the 9 attitude models. The most consistent predictors were emotional nature connection and personal values (significant in 4–6 out of 9 models), rather than external phenomena (significant in 0–5 models). However, the poorest farmers had lower scores on the agreement with prioritizing nature over development (𝛽 = –0.52, 95% CI: –0.96 to –0.07). Qualitative data also indicated that economic barriers hinder forest conservation on farms. These results suggest that biospheric, traditionalistic, and altruistic motivations promote people's proconservation attitudes, but nurturing these latent motivations is unlikely to improve conservation outcomes if material poverty remains unaddressed. Integrating the inner–outer perspective into conservation thinking and practical interventions could foster environmental stewardship and increase human well-being.     

Local and regional genetic connectivity in a Caribbean coral reef fish

Coupled bio-physical models of larval dispersal predict that the Costa Rica–Panama (CR–PAN) reefs should constitute a demographically isolated region in the western Caribbean. We tested the hypothesis that CR–PAN coral reef fish populations would be isolated from Mesoamerican Barrier Reef System (MBRS) populations. To test that, we assessed population genetic structure in bicolor damselfish (Stegastes partitus) from both regions. Adult fish were genotyped from five reefs in CR–PAN and from four reefs along the MBRS at 12 microsatellite loci. Between-region F _ST (F _ST = 0.0030, P < 0.005) and exact test (x ² = 74.34, df = 18, P < 0.0001) results indicated that there is weak but significant genetic differentiation between regions, suggesting some restriction in connectivity along the Central American coastline, as predicted by bio-oceanographic models. Additionally, there is among-site genetic structure in the CR–PAN region, relative to the MBRS and between regions, suggesting higher self-recruitment within CR–PAN. This finding may be explained by differences in habitat characteristics.     

Resprouting as a persistence strategy of tropical forest trees: relations with carbohydrate storage and shade tolerance

Resprouting is an important persistence strategy for woody species and represents a dominant pathway of regeneration in many plant communities, with potentially large consequences for vegetation dynamics, community composition, and species coexistence. Most of our knowledge of resprouting strategies comes from fire-prone systems, but this cannot be readily applied to other systems where disturbances are less intense. In this study we evaluated sapling responses to stem snapping for 49 moist-forest species and 36 dry-forest species from two Bolivian tropical forests. To this end we compared in a field experiment the survival and height growth of clipped and control saplings for a two-year period, and related this to the shade tolerance, carbohydrate reserves, and the morphological traits (wood density, leaf size) of the species. Nearly all saplings resprouted readily after stem damage, although dry-forest species realized, on average, a better survival and growth after stem damage compared to moist-forest species. Shade-tolerant species were better at resprouting than light-demanding species in moist forest. This resprouting ability is an important prerequisite for successful regeneration in the shaded understory, where saplings frequently suffer damage from falling debris. Survival after stem damage was, surprisingly, only modestly related to stem reserves, and much more strongly related to wood density, possibly because a high wood density enables plants to resist fungi and pathogens and to reduce stem decay. Correlations between sampling performance and functional traits were similar for the two forest types, and for phylogenetically independent contrasts and for cross-species analyses. The consistency of these results suggests that tropical forest species face similar trade-offs in different sites and converge on similar sets of solutions. A high resprouting ability, as well as investments in stem defense and storage reserves, form part of a suite of co-evolved traits that underlies the growth-survival trade-off, and contributes to light gradient partitioning and species coexistence. These links with shade tolerance are important in the moist evergreen forest, which casts a deep, more persistent shade, but tend to diminish in dry deciduous forest where light is a less limiting resource.     

Nonlinear relationships between vital rates and state variables in demographic models

To accurately estimate population dynamics and viability, structured population models account for among-individual differences in demographic parameters that are related to individual state. In the widely used matrix models, such differences are incorporated in terms of discrete state categories, whereas integral projection models (IPMs) use continuous state variables to avoid artificial classes. In IPMs, and sometimes also in matrix models, parameterization is based on regressions that do not always model nonlinear relationships between demographic parameters and state variables. We stress the importance of testing for nonlinearity and propose using restricted cubic splines in order to allow for a wide variety of relationships in regressions and demographic models. For the plant Borderea pyrenaica, we found that vital rate relationships with size and age were nonlinear and that the parameterization method had large effects on predicted population growth rates, X (linear IPM, 0.95; nonlinear IPMs, 1.00; matrix model, 0.96). Our results suggest that restricted cubic spline models are more reliable than linear or polynomial models. Because even weak nonlinearity in relationships between vital rates and state variables can have large effects on model predictions, we suggest that restricted cubic regression splines should be considered for parameterizing models of population dynamics whenever linearity cannot be assumed.     

Determination of total and bioaccessible metals in airborne particulate matter from an urban and a rural area at Sarajevo

Airborne particulate matter of up to 10 µm collected at an urban and a rural area at Sarajevo in 2013 and 2014 was acid digested for determination of total concentrations or extracted with synthetic gastric juice for the bioaccessible fractions of Cd, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn and determined by graphite furnace and flame atomic absorption spectrometry. The total concentrations of Cr, Cu, Fe, Mn, Pb, and V were higher at the urban site, while those of Cd, Ni, and Zn were virtually equal at both sites. The average bioaccessible fractions exhibited the following trend at both sites: Fe > Zn > Cu > Mn > Pb > Cr > V > Ni > Cd. Enrichment factors and daily intake of metals by inhalation were calculated.     

Effect of inoculation in composting processes: modifications in lignocellulosic fraction

Three microbial isolates, identified as Bacillus shackletonni, Streptomyces thermovulgaris and Ureibacillus thermosphaericus were tested as inoculants in composting processes in relation to their capacity to improve lignocellulose degradation. Different wastes from agricultural activities were used as raw material for the heaps: pepper plant waste (PPW) as the main component and olive-oil mill waste (OMW), almond shell (AS), pruning waste (PW) and rice straw (RS) as additives. Cellulose was more extensively degraded than hemicellulose and lignin, although the use of inoculants (B. shackletonni and S. thermovulgaris) improved the action of the autochthonous microbiota just in the AS heaps. A higher efficiency was observed for lignin, since lower concentrations of this polymer were detected in the inoculated heaps in relation to control heaps. U. thermosphaericus was the most efficient microorganism since inoculation with this strain decreased the final lignin content in a range between 17.23% and 24.34%. S. thermovulgaris and B. shackletonni led to a higher reduction of the lignin levels in the OMW and PW heaps (14.25% and 19.07% less lignin than control heaps) and OMW (13%), respectively. The composting process can therefore be improved by means of inoculation if the microorganisms used for this purpose are appropriate for the characteristics of the raw material.     

Isotherms and sequential extraction procedures for evaluating sorption and distribution of heavy metals in soils

Heavy metals are potentially toxic to human life and the environment. Their contaminating effect in soils depends on chemical associations. Hence, determining the chemical form of a metal in soils is important to evaluate its mobility and bioavailability. We utilized a sequential extraction procedure and sorption isotherms (monometal and competitive) to evaluate the mobility and distribution of Cd, Cu, Ni, Pb, and Zn in four soils differing in their physicochemical properties: Calcixerollic Xerochrepts (Cx1 and Cx2), Paralithic Xerorthent (Px) and Lithic Haplumbrept (Lh). Most of the metals retained under point B conditions of sorption isotherms were extracted from the more mobile fractions: exchangeable and carbonates, in contrast with the profiles of the original soils where metals were preferently associated with the residual fraction. In soils having carbonate concentration under 6% (Cx1 and Lh), the exchangeable fraction was predominant, whereas in calcareous soils (Cx2 and Px) metals extracted from carbonates predominated. Partitioning profiles were in accordance with the affinity sequences deduced from the initial slope of isotherms and showed that the soils had a greater number of surface sites and higher affinity for Pb and Cu than for Cd, Ni, or Zn. In general, the simultaneous presence of the cations under study increased the percentages of metals released in the exchangeable fraction. The tendency towards less specific forms was more noticeable in Cx2 and Px soils and for Ni, Zn, and Cd. The affinity of inorganic surfaces was larger for Zn than for Cd or Ni, but the affinity of organic surfaces was larger for Cd or Ni than for Zn.