The color changes corresponding to chromophore structures in lignin caused by exposure of Eucalyptus（Eucalyptus grandis and E. urophylla）to heat were investigated. Eucalyptus wood samples were heated in saturated steam atmospheres for 10 h at 110℃, 130℃, and 150℃. The lignin was isolated before and after heat treatment. The physicochemical properties of the lignin and changes in chromophore structures during heat treatment was evaluated through wet chemical analysis, FTIR, UV-Vis, GPC, XPSand 13C-NMR. The color of the wood became darker and redder with the increase in pressure and temperature. Depolymerization and dehydration reactions occurred via demethoxylation with heat treatment in saturated steam at 110℃ or 130℃. Lignin condensed to form insoluble compounds after heat treatment in saturated steam at 150℃. G units increased and S units decreased through demethylation during heat treatment, as revealed by FTIR and 13C-NMR analysis.

Mechanical properties of three-dimensional (3D) printed resin can be improved by decreasing oxygen concentrations during post-curing, and nitrogen saturated post-curing has been applied for the purpose. This study aimed to evaluate and compare the color stability of 3D printed resin crowns post-cured in normal air and nitrogen saturated conditions. Crowns were fabricated with 3D printer and post-cured in normal air (control group; air) or nitrogen saturated condition (experimental group; nitrogen). The specimens in each group were subdivided into four subgroups, each exposed to different discoloration agents: distilled water, coffee, wine, and curry. Post-immersion color changes were measured using a digital spectrophotometer and analyzed through repeated measures ANOVA. Fourier Transform Infrared (FT-IR) spectroscopy evaluated the degree of conversion of resin over immersion times for both post-curing conditions. Comparing the effects of post-curing conditions, significant difference was found between control and experimental groups over immersion time in wine and curry subgroups. In FT-IR analysis, there was significant difference in degree of conversion between the air and nitrogen groups from 10 to 300 seconds. The findings suggest that nitrogen saturated post-curing can potentially enhances the conversion rate of 3D printed resin crowns, thereby improving their color stability.

Efforts to enhance carbon storage in forest ecosystems through policy and management decisions rely on accurate forest biomass assessments. However, most forest inventories consider tree mortality the only form of aboveground biomass loss, overlooking other important factors, such as wood decay in living trees. In this study, using linear mixed-effects models, we delve into the sustainability of mature and over-mature deciduous forests in Latvia by conducting a comprehensive analysis of stem rot severity, identifying species for which the impact of stem rot on their carbon stock reduction was most significant. The analysis focused on determining the proportion of discolored wood, decomposed wood, and hollow spaces within the stems of 190 living deciduous trees commonly found in hemiboreal forests. The study reveals a greater extent of stem rot and more extensive decay in Populus tremula trees than in Betula spp., Alnus glutinosa, and Alnus incana. It emphasizes the influence of tree species, age, and diameter at breast height on stem rot proportions. The stump rot area significantly predicts the amount of decomposed and discolored wood within the stem. The study provides valuable insights for sustainable forestry practices and highlights challenges in estimating stem rot severity, emphasizing the need for comprehensive diagnostic methods.

Radially polymerized dendritic compounds are nowadays an established polymer category next to their linear, branched and cross-linked counterparts. Their uncommon tree-like architecture is characterized by adjustable internal cavities and external groups. They are therefore exceptional absorbents and this attainment of high concentrations into their interior renders them ideal reac-tion media. In this framework they are applied in many environmentally benign implementa-tions. One of the most important among them is water purification though pollutant decomposi-tion. Simple and composite catalysts and photo-catalysts containing dendritic polymers and ap-plied in water remediation will be discussed jointly with some unconventional solutions and fu-ture prospects.

Terrestrial algae are the group of photosynthetic organisms, which can survive in extreme conditions. pH is one of the most important factor, influencing on distribution of algae, both in aquatic and terrestrial ecosystems. The influence of different pH levels on cell volume and other morphological characters of authentic and reference strains of Chlorella vulgaris, Bracteacoccus minor, Pseudoccomyxa simplex, Chlorococcum infusionum, and Vischeria magna were studied. Chlorella vulgaris and Pseudoccomyxa simplex were the most resistant species, retaining its morphology in range of pH 4-11,5. The change of pH towards acidic and alkaline levels caused the increase of volume of Pseudoccomixa simplex and Vischeria magna cells according to polynomial regression model. Volume of Chlorella vulgaris cells increased from low to high pH according to linear regression model. Changes of pH levels did not have a significant impact on volume of Bracteacoccus minor and Chlorococcum infusionum cells. Low and high levels of pH caused thickening of cell walls of Chlorococcum infusionum and increase of oil containing substances in Vischeria magna and Bracteacoccus minor cells. Our study revealed a high resistance of studied species to extreme level of pH, which allow recommend these strains for broader use in biotechnology and natures protection.