INMdok (Leibniz Institute for New Materials)
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Biological upcycling of polystyrene into ready-to-use plastic monomers and plastics using metabolically engineered Pseudomonas putida
Full text linkThe persistent accumulation of plastic waste, particularly polystyrene (PS), poses significant environmental challenges because of its extensive use and low recycling rates. Addressing these challenges necessitates innovative and sustainable solutions. This study presents a strategy to upcycle PS waste into valuable chemical products, including adipic acid, hexanediol, hexamethylenediamine, and nylon-6,6, using metabolically engineered Pseudomonas putida KT2440. This process involves the photolytic degradation of PS into benzoic acid, followed by microbial conversion into cis,cis-muconate (MA) and chemical synthesis of the final products. The engineered strains withstood 30 mM concentrations of PS-derived aromatics and converted them stoichiometrically into MA in the presence of glucose as a growth substrate. 13C metabolic flux analysis revealed energy and redox limitations in the presence of 25 mM benzoate and 300 mM MA. The cells responded to stress by enhancing the flux for periplasmic glucose oxidation and fluxes through the NADPH-forming dehydrogenases; this process caused more than 40 % glucose‑carbon loss into byproducts. Fine-tuned dynamic glucose and benzoate feeding enabled high-level MA production. Energy-optimized genome-reduced strains were used to increase carbon efficiency. A final MA titer of over 65 g L−1 was achieved in fed-batch fermentation. This process was demonstrated using the glucose derived from a viscose textile waste blend as the growth substrate and resulted in fully waste-based products. The resulting adipic acid and hexamethylenediamine were polymerized into nylon-6,6 with properties comparable to those of petrochemical-derived polymers, revealing a sustainable pathway for PS upcycling. This research provides a proof-of-concept for bacterial upgrading of PS-derived substrates and a viable method for managing plastic waste and producing valuable chemical products
Gooey stuff: the psychophysics of unpleasantness in response to touching liquids
Full text linkThere is a growing scientific interest in material unpleasantness, yet the role of distinct physical parameters in perceptual and affective haptic experiences with liquids remains to be fully understood. To address this, we investigated how perceptual qualities of liquids relate to measurable physical properties and unpleasantness during active touch. We prepared 15 custom liquid samples using everyday materials. Rheological measurements showed that samples varied between physical viscosity 1mPA s and 45 Pa s . Participants explored each sample using circular rubbing motions with their index fingers. A camera system tracked finger movements, and a force sensor revealed applied normal forces, pull-off force (PoF) and the coefficient of friction (CoF). We compared these physical properties with the perceptual dimensions from our earlier work: perceived viscosity and slipperiness. Perceived viscosity correlated strongly with both physical viscosity and PoF, but not with CoF. Conversely, perceived slipperiness was associated with CoF, but not PoF or physical viscosity, demonstrating distinct links between physics and perception of liquids. Interestingly, PoF but not CoF was significantly linked to unpleasantness, suggesting that PoF but not CoF is crucial for liquid unpleasantness. These findings advance our understanding of how distinct physical properties relate to perceptual and affective experiences of liquids
Elastocalorics: Cooling Buildings With Metals That Stretch
Full text linkElastocaloric technology is a new way to heat and cool spaces by using stretchy metals, called shape-memory alloys, instead of harmful refrigerant gases. When these metals are squeezed or stretched, they heat up; and when they relax, they cool down. This process is called the elastocaloric effect and it is more energy efficient than traditional cooling systems, making it a cleaner, greener alternative. Elastocaloric systems could cool homes, schools, and workplaces, and they could refrigerate food and medicine in areas with limited electricity. Researchers are also testing this technology for cooling and heating of electric vehicles, where it could help conserve battery life, and for heating buildings in colder climates. Despite its promise, elastocaloric technology faces challenges, such as improving the durability of materials and making the shape-memory alloys more affordable. With continued research, this technology could someday help to reduce greenhouse gas emissions, lower energy costs, and bring life-saving cooling to more people all over the world
Pull-off strength of mushroom-shaped fibrils adhered to rigid substrates
No full textThe exceptional adhesion properties of biological fibrillar structures -- such as those found in geckos -- have inspired the development of synthetic adhesive surfaces. Among these, mushroom-shaped fibrils have demonstrated superior pull-off strength compared to other geometries. In this study, we employ a computational approach based on a Dugdale cohesive zone model to analyze the detachment behavior of these fibrils when adhered to a rigid substrate. The results provide complete pull-off curves, revealing that the separation process is inherently unstable under load control, regardless of whether detachment initiates at the fibril edge or center. Our findings show that fibrils with a wide, thin mushroom cap effectively reduce stress concentrations and promote central detachment, leading to enhanced adhesion. However, detachment from the center is not observed in all geometries, whereas edge detachment can occur under certain conditions in all cases. Additionally, we investigate the impact of adhesion defects at the fibril center, showing that they can significantly reduce pull-off strength, particularly at high values of the dimensionless parameter \c{hi}. These insights contribute to the optimization of bio-inspired adhesives and microstructured surfaces for various engineering applications
Fragments of viral surface proteins modulate innate immune responses via formyl peptide receptors
Full text linkFormyl peptide receptors (FPRs) are pattern recognition receptors well-known for bacterial pathogen sensing. We here identified activator and inhibitor motifs for FPRs that are present on surface proteins of various viral pathogens. Peptides containing these motifs interact with all FPR family members and modulate various important immune functions in innate immune cells. Viral breakdown products comprising these motifs were found in patients with COVID-19. In the spike protein, many activators are found in highly mutagenic regions, whereas the inhibitor motif is located in a conserved domain that also exists in further unrelated viruses. The physiochemical properties of FPR1 activators correlate with the occurrence of protein aggregation hotspots. Such hotspots are present on various surface proteins of unrelated viruses that can also activate FPRs. This points toward a general contribution of FPRs in modulating antiviral immune responses during many distinct viral infections
NER for Specialized Scientific Domains: Fine-Tuning on Patents for Plasma Technology and Battery Materials
Full text linkDomain-specific Named Entity Recognition (NER) allows to identify and extract specific types of entities from text. In particular for technical domains such as plasma technology and battery materials extracting and aligning such entities with complex (structured) semantic information such as in Knowledge Graphs (KG) plays a crucial role. In this work, we fine-tuned SciBERT, BERT-for-Patents, and BatteryBERT for domain-specific NER based on systematically constructed annotated datasets specific to the regarded domain. Despite the relatively limited size of the training data, particularly for battery materials, the models achieved strong overall performance. By leveraging the linguistic knowledge encoded in the pretrained models, combined with domain-specific patterns learned from the training datasets, the developed models effectively identified and classified entities based on their contextual usage. Our evaluation demonstrated that fine-tuning domain-adapted pretrained models significantly enhance NER effectiveness in specialized scientific and technological domains
Transient Formation of Single Layer Diamond During Friction Force Microscopy of SiC‐Supported Epitaxial Graphene
Full text linkCarbon allotropes are crucial to advanced interfaces to control friction and wear because of their unique range of mechanical properties: from diamond's hardness to graphite's lubricity. Friction force microscopy (FFM) is reported for diamond tips sliding on SiC(0001)‐supported epitaxial graphene. A sharp friction increase is observed at a threshold normal force, linked to an intermittent graphene rehybridization. Comparing the FFM response of a diamond tip to that of a previously studied silicon tip with a comparable radius reveals a similar abrupt friction increase, though at roughly half the threshold force. Atomistic simulations of SiC(0001)‐supported graphene sliding against hydroxylated amorphous carbon (a‐C) and silicon oxide show low shear stress at low pressures for both systems. The shear stress increases at higher pressures due to bond formation between graphene and the counterbody. For a‐C, the transition threshold shifts to higher pressures, consistent with FFM results. In simulations with high normal pressures, epitaxial graphene undergoes a structural transformation into single‐layer diamond, contributing to the abrupt increase in friction. The graphene structure recovers after lifting the a‐C counterbody, demonstrating structural robustness under tribological stress. These findings provide insights into the stability of low‐friction interfaces between epitaxial graphene and key materials for current micro‐electro‐mechanical systems (MEMS
Optimized electrochemical recovery of lithium-ions from spent battery cells using carbon-coated lithium iron phosphate
Full text linkLithium-ion batteries play a crucial role in powering electric vehicles and portable electronics, making them indispensable in modern technology and driving a significant increase in global lithium demand. With more and more batteries reaching their end of life and the challenges of lithium extraction, including rising prices, geopolitical constraints, and environmental concerns, the efficient recovery of lithium from spent battery cells is crucial for sustainable battery recycling. While state-of-the-art battery recycling focuses mainly on pyro- and hydrometallurgical methods, electrochemical recycling methods can be an environmentally friendly, energy-efficient, and cost-effective alternative. This study optimizes an energy-efficient electrochemical method for selective LiCl extraction from leaching solutions derived from cathode materials of a typical battery cell format (lithium cobalt oxide (LCO)). This places our electrochemical separation within the hydrometallurgical processing of spent battery materials (black mass) and prior to subsequent lithium refining steps. Applying carbon-coated lithium iron phosphate (LFP) electrodes for selective lithium recovery yielded an average uptake capacity of 11.4 mgLi gLFP/C-1 over 300 cycles, maintaining a significant discharge capacity (30 mAh g-1) after 500 cycles
Combining Structured Data with Domain Knowledge in Battery Materials Research: The Case of Conductive Networks
Full text linkBatteries contain combinations of materials that undergo electrochemical reactions to convert chemical into electrical energy. Battery research relies on experience and know-how. Important materials and processing data can get overlooked, remain undocumented, or even lost. To bridge the gap between fundamental materials research and battery process engineering, it is essential to generate, analyze, and, most importantly, link intermediate knowledge for future use. Here, it is shown how to combine domain knowledge and a data-driven approach to understanding material–property relationships in the case of conductivity networks of carbon black. The Battery Production and Characterisation Ontology (BPCO) is employed to identify hypotheses that connect battery processing to material domain knowledge. The material's interactions between carbon black, polyvinylidene flouride, and solvents in the BPCO are characterized. These materials combine to form the classical microstructure in battery electrodes for the electrical conductivity. It is demonstrated how new links to the BPCO, verified via materials-processing relationships, and the interim results are identified as intermediate data
Designing Smartly: Understanding the Crystallinity of Melt Electrowritten Scaffolds
Full text linkMelt Electrowriting (MEW) is a powerful technique in tissue engineering, enabling the precise fabrication of scaffolds with complex geometries. One of the most important parameters of MEW is collector speed, which has been extensively studied in relation to critical translation speed. However, its influence on crystallinity was overlooked. Crystallinity is crucial for the mechanical properties and degradation behavior of the scaffolds. Therefore, in this study, we present how printing affects the crystallinity of fibers and the resulting mechanical properties of MEW scaffolds. In systematic analysis, we observed a significant reduction in scaffold crystallinity with increased speed, as evidenced by wide-angle X-ray scattering. This decrease in crystallinity was attributed to differences in cooling rates, impacting the polycaprolactone molecular orientation within the fibers. By using tensile testing, we observed the decrease in scaffold Young's modulus with increasing collector speed. Given the relation between crystallinity and mechanical properties of the material, we developed a finite element analysis model that accounts for changes in crystallinity by employing distinct bulk Young's modulus values to help characterize scaffold mechanical behavior under tensile loading. The model reveals insights into scaffold stiffness variation with different architectural designs. These insights offer valuable guidance for optimizing 3D printing to obtain scaffolds with desired mechanical properties