Environmental Sustainability and Physicochemical Property Screening of Chitin and Chitin-Glucan from 22 Fungal Species.

Thanks to its biobased character with embedded biogenic carbon, chitin can aid in the transition to a sustainable circular economy by replacing fossil carbon from the geosphere. However, meeting current demands for material availability and environmental sustainability requires alternative methods limiting conventional chemical and energy-consuming chitin extraction from crustaceans. To assist future chitinous bioproduct development, this work analyzes the physicochemical properties and potential environmental sustainability of fungal chitin-glucan complexes. A conventional isolation procedure using sodium hydroxide, a weak acid, and short reaction times are applied to the fruiting body of 22 fungal species. Besides, the valorization of underutilized waste streams including Agaricus bisporus and Agaricus brunnescens stipes is investigated. The carbohydrate analysis renders chitin fractions in the range of 9.5-63.5 wt %, while yields vary from 4.2 to 29.9%, and the N-acetylation degree in found in between 53.0 and 98.7%. The sustainability of the process is analyzed using life cycle assessment (LCA), providing impact quantification for global warming potential, terrestrial acidification, freshwater eutrophication, and water use. With 87.5-589.3 kg·CO2-equiv per kilo, potentially lower global warming potential values in comparison to crustacean chitin are achieved. The crystallinity degree ranged from 28 to 78%, while the apparent chitin crystalline size (L020) is between 2.3 and 5.4 nm. Ten of the species yield α-chitin coexisting with semicrystalline glucans. Zwitterionic properties are observed in aqueous solutions, shifting from cationic to anionic at pH 4.5. With its renewable carbon content, fungal chitin is an environmentally sustainable alternative for high-value applications due to its balance of minimal treatment, low carbon footprint, material renewability, ease of isolation, thermal stability, zwitterionic behavior, biodegradability, and noncytotoxicity.

Psychophysiological correlates of chronic worry: cued versus non-cued fear reaction.

Worry has been defined as a chain of thoughts and images that promote mental attempts to avoid anticipation of potential threats. From this perspective worry can be conceptualized as a state of anticipatory anxiety or non-cued fear reaction. The present study examines high and low chronic worriers during cued and non-cued defense reaction paradigms and during resting and self-induced worry periods. The non-cued procedure was based on the cardiac defense paradigm, whereas the cued procedure was based on the startle probe paradigm using pleasant, neutral and unpleasant pictures as cues. High worriers, compared to low worriers, showed (a) a greater cardiac defense response in the non-cued fear response paradigm, (b) no differences in eye-blink in the startle probe paradigm, (c) reduced skin conductance reactivity during the startle probe paradigm and (d) reduced Respiratory Sinus Arrhythmia, accompanied by increased respiratory rate and decreased expiratory period, during the resting period. These results support the notion of chronic worry as a state of anticipatory anxiety, accompanied by indices of reduced vagal control, that modulates non-cued defense reactions.