Kompetenzzentrum Holz

Abstract Wooden cubes from eight European species – spruce ( Picea abies ), pine ( Pinus sylvestris ), larch ( Larix sp.), oak ( Quercus sp.), beech ( Fagus sylvatica ), ash ( Fraxinus excelsior ), birch ( Betula sp.), and poplar ( Populus sp.) – were tested to investigate the relationship between thermal conductivity and density. Thermal conductivity was measured in the longitudinal, radial, and tangential directions on a total of 215 conditioned samples, each species covering a broad density range. Linear regression models were fitted for each species and anatomical direction. The gradients of regression models revealed species- and direction-specific differences. Longitudinal thermal conductivity showed the greatest density dependence, with spruce, birch, and poplar exhibiting gradients up to 40 % steeper than oak. In contrast, oak displayed the highest gradient in the radial and tangential directions, while other species showed up to 19 % (radial) and 13 % (tangential) lower values. The results demonstrate that, beyond density, anatomical direction and species-specific properties must be considered in thermal conductivity modeling of wood.

Dieser Eintrag enthält eine Zusammenstellung der Ergebnisse einer Online-Umfrage zur Nutzung von Fernerkundungsdaten und -produkten zur Erkennung von Waldstörungen in Deutschland sowie den dazugehörigen Fragebogen. Da sich die Umfrage an forstliche Praktikerinnen und Praktiker in Deutschland richtete, sind sämtliche Materialien in diesem Eintrag ausschließlich in deutscher Sprache verfügbar. Die Umfrage wurde im Rahmen des Forschungsprojekts ForstEO durchgeführt. Das Projekt ForstEO („Nutzung von Erdbeobachtungsdaten zur Erkennung klimabedingter Waldschäden in Deutschland“) wird durch das Bundesministerium für Landwirtschaft, Ernährung und Heimat (BMLEH) sowie das Bundesministerium für Umwelt, Klimaschutz, Naturschutz und nukleare Sicherheit (BMUKN) über den Waldklimafonds gefördert. This repository contains a compilation of results from an online survey on the use of remote sensing data and products for detecting forest disturbances in Germany, as well as the associated questionnaire. As the survey focused on forest practitioners in Germany, all materials in this repository are provided in German. The survey was conducted as part of the research project ForstEO. The ForstEO project (“Use of Earth Observation to Detect Climate-Induced Damage to Forests in Germany”) is funded by the Federal Ministry of Agriculture, Food and Home Affairs (BMLEH) and the Federal Ministry for the Environment, Climate Protection, Nature Conservation and Nuclear Safety (BMUKN) through the Forest Climate Fund.

The COVID-19 pandemic has inflicted unprecedented pressure on communities and healthcare systems around the world. An outstandingly broad and intensive investigation of possible therapeutic interventions is currently taking place to prevent similar future threats to the global population. Investigating the related mechanisms of action is often complex and time consuming. Moreover, research on biochemical interactions of new drugs involves a considerable amount of effort, consequently bearing inherent financial and operational risks for pharmaceutical companies. An interesting approach to counteract colonization and infection is the concept of antiseptic treatment in vivo. Antiseptics are cost-effective and globally accessible, due to their ease of production, transportation and handling. A broad spectrum of active agents with different properties is readily available. One of these substances is hypochlorous acid (HOCl), which is also a naturally occurring biocidal agent and as such part of the innate immune system. Its successful history of medical use in wound treatment, combined with low cytotoxicity and documented efficacy against various pathogens, suggests that HOCl might be an effective agent for treating the respiratory mucosa. This could potentially enable therapeutic inhalation for combating bacterial infections and viral pathogens such as human respiratory syncytial, influenza, and SARS-CoV-2 viruses, which will be discussed in the present article.

This study investigates the processing of shea nut shells (SNSs), an abundant agricultural waste, into porous activated carbon for supercapacitor electrodes through a two-stage thermal treatment involving pyrolysis and physical activation with CO2 and steam. The aim was to develop sustainable, high-performance electrode materials while addressing waste management. Carbonization followed by activation yielded 16.5% (CO2) and 11.3% (steam) activation yields, with total yields of 4.3% and 2.9%, respectively. CO2 activation produced carbon (AC_CO2) with a specific surface area (SBET) of 1528 m2 g−1 and a total pore volume of 0.72 cm3 g−1, a graphitization degree (ID/IG = 1.0), and low charge transfer resistance (9.05 Ω), delivering a specific capacitance of 47.5 F g−1 at 0.5 A g−1, an energy density of 9.5 Wh kg−1 at 299 W kg−1, and a fast discharge time of 2.10 s, ideal for power-intensive applications. Steam activation yielded carbon (AC_H2O) with a higher specific surface area (1842 m2 g−1) and pore volume (1.57 cm3 g−1), achieving a superior specific capacitance of 102.2 F g−1 at 0.5 A g−1 and a power density of 204 W kg−1 at 9.2 Wh kg−1, suited for energy storage. AC_CO2 also exhibited exceptional cyclic stability (90% retention after 10,000 cycles). These findings demonstrate SNS-derived activated carbon as a versatile, eco-friendly material, with CO2 activation optimizing power delivery and steam activation enhancing energy capacity, offering tailored solutions for supercapacitor applications and sustainable waste utilization.

Electrospun poly(vinylidene fluoride) (PVDF)-based gel polymer electrolyte (GPE) is considered a highly promising candidate for a sodium-ion (Na-ion) battery because of its flexibility, light weight, 3D interconnected structure, and mechanical integrity. However, the pristine electrospun PVDF membrane-based GPE struggles to meet the prerequisite of Na-ion battery due to high crystallinity, low ionic conductivity, and deterioration of mechanical integrity. In order to overcome these issues, a nonwoven membrane was prepared comprising PVDF/halloysite nanoclay (HNT) nanocomposite (EPHN) as GPE for Na-ion batteries. The crystallinity and average fiber diameter for PVDF nanofibers decreased upon the addition of HNT. In contrast, the tensile strength, puncture strength, and dimensional stability of an electrospun PVDF membrane improved upon the addition of HNT. Due to high porosity (86%), electrolyte uptake (535%), and wettability, the ionic conductivity of the EPHN membrane (7.1 mS/cm) improved significantly compared with a pristine electrospun PVDF membrane along with augmented electrochemical stability (5.3 V). EPHN-based GPE exhibited a specific capacity of 162 mAh g–1 and a Coulombic efficiency of 98% after 100 cycles. EPHN-based GPE outperformed the pristine electrospun PVDF membrane and commercial polypropylene (PP) separator. The EPHN-based GPE in Na-ion batteries offers insight and approaches for further development of GPE to accomplish the properties demanded for real-world applications.

The use of cellulose fiber-filled polypropylene (PP) composites in combination with foam injection molding has enabled the lightweight design of injection-molded parts. The study provides achievements for the physical foam injection molding (MuCell®) process of PP–cellulose fiber compounds by using CO2 as the direct foaming agent, including a comparison of MuCell® foaming with N2 and a comparison to a chemical foaming process. Weight and density reductions, foam structure and specific mechanical properties are highly dependent on the applied processing parameters. The maximum weight reduction reached values of up to 16%, and density reduction even reached 33% in relation to the compact plates. The extent of weight and density reduction could be adjusted, among other factors, by a reduction in the shot volume. Setting the density reduction to 22% allowed for simultaneously decreasing weight while sustaining the specific flexural properties and limiting the loss of specific impact strength. By using optimized FIM parameters, the mechanical performance could be improved, with specific modulus values even outperforming the compact reference sample. This presents a significant benefit for the preparation of lightweight products and sets the basis for further optimization and modeling studies.

Lignocellulose has served as precursor material for carbon fibers (CFs) before fossil-based polymers were discovered as superior feedstock. To date, CFs made from polyacrylonitrile have dominated the market. In search of low-cost carbon fibers for applications with medium strength requirements, cellulose and lignin, either as individual macromolecule or in combination, have re-gained interest as renewable raw material. In this study, cellulose with 30 wt% lignin was dry-jet wet-spun into a precursor filament for bio-based carbon fibers. The stabilization and carbonization conditions were first tested offline, using stationary ovens. Diammonium sulfate (DAS) and diammonium hydrogen phosphate were tested as catalysts to enhance the stabilization process. Stabilization is critical as the filaments’ strength properties drop in this phase before they rise again at higher temperatures. DAS was identified as a better option and used for subsequent trials on a continuous carbonization line. Carbon fibers with ca. 700 MPa tensile strength and 60–70 GPa tensile modulus were obtained at 1500 °C. Upon further carbonization at 1950 °C, moduli of >100 GPa were achieved.