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Continuous carbon fibers (CFs) are often employed to improve the mechanical performance of ceramic materials due to their lightweight nature, high stiffness, and strength. Vat photopolymerization (VPP) is a promising additive manufacturing technology for printing CFs-reinforced ceramic materials, offering high resolution and production efficiency. Nevertheless, printing CFs-reinforced ceramic materials with VPP technology has been challenging due to its unique principles. To address this research gap and inspired by biological structures like the golden spiral of nautilus and the sponge bone needle, this study presents a novel approach using VPP technology to fabricate a sponge bone needle bionic structure (SBNBS) for the first time. Experimental results show a positive correlation between the quantity of CF bundles and the flexural strength, fracture toughness, and fracture work. Furthermore, the SBNBS with five CF bundles demonstrates significant improvements, showing ultimate flexural strength, fracture toughness, and fracture work values six times, six times, and 180 times higher, respectively, compared to a pure Al2O3counterpart. Finite element methods are employed to uncover load transfer mechanisms and fracture behaviors, while molecular dynamic simulations provide insights into atomic-level strengthening and toughening mechanisms.

A continuous fiber reinforced two-matrix composites with multi-cavity structure was fabricated by a co-extrusion method, combining the excellent wettability of thermosetting resin to fiber and the wonderful extrusion forming ability of thermoplastic for nozzle based additive manufacturing (AM). Diversified component materials were utilized to enrich database for the AM of continuous fiber composites, including continuous carbon fiber (CCF), continuous basalt fiber (CBF), short fiber reinforced polyamide (SFRPA), polyamide (PA), polylactic acid (PLA) and epoxy resin. The tensile and flexural tests were conducted to investigate the effect of component materials on the mechanical properties. The micro-structures of printing filament and the fracture morphology of samples were characterized by optical microscope (OM) and scanning electron microscopy (SEM), respectively. A novel numerical model based on Peridynamics (PD) was proposed for the simulation of failure model. The three-dimensional (3D) printed continuous fiber reinforced two-matrix composites with multi-cavity structure show dissimilar mechanical behavior and failure characteristic for different combinations of component materials. The micro-structure of the fiber bundle pre-impregnated by epoxy resin after printing has a great influence on the mechanical properties and fracture modes of the samples. The failure modes mainly include pullout and breakage of fiber, stress whitening and crack of matrix, and interfacial debonding. The PD model effectively captures the tensile and flexural failure characteristic of 3D printed composites with multi-cavity structure. The results from experimental analysis and numerical simulation have reference significance for structural optimization and failure prediction of continuous fiber composites printed by co-extrusion process.

Fungal alkylresorcinols are a class of polyketides, which are commonly synthesized by the hybridization of highly reducing polyketide synthase (hrPKS) with non-reducing polyketide synthase (nrPKS). In this study, we identified and demonstrated a new assembly model for synthesizing alkylresorcinol (scirpilin A, 1), which was accomplished by collaboration of a hrPKS (FscA) and a type III PKS (FscB). Furthermore, three post-tailoring enzymes (FscC, FscD, and FscE) act iteratively on 1skeleton, including successive 14e−oxidation of inert carbons, di-halogenation, and di-methylation, to form highly oxidized and multi-substituted alkylresorcinols. Our work presents an unusual synthesis manner of alkylresorcinols, sheds light on the collaborative mechanism between hrPKS and type III PKS and provides three valuable enzymatic catalysts for the tailoring of alkylresorcinol family natural products in future.

Owing to their high thermal stability, oxidation resistance, and corrosion resistance, polymer-derived ceramics (PDCs) have attracted extensive attentions to fabricate complex-shaped ceramic parts that can be used in high-tech industries. While flexible PDCs offer structural reconfiguration, methods for inducing shape changes primarily rely on mechanical loads, such as manual loading, motors, or pneumatic pumps, which is considered impractical and requires complex control systems. To address these issues, a vat photopolymerization (VPP)-based four-dimensional (4D) printing method has been proposed and developed to manufacture PDCs with reconfigurable and shape memory effects for the first time. This innovative 4D printing method is highly programmable and compatible with VPP technology, allowing the fabrication of high-resolution, intricately designed ceramic structures with a high solid content. Through a two-step curing process, autonomous shape transformations of the PDCs have been achieved.

To reduce the waste of profiles during the rolling process, different rolling forming processes were studied based on the finite element method. The straight edge allowance generated by different forming processes during the rolling process was analyzed. Simulation results showed that the pre-bending/side roll lifting rolling process with the same side roll displacement produced the least straight edge allowance, reducing the straight edge allowance from 30.3981 to 2.79983 cm for the three-roll downward processing, a 90% decrease, and reducing profile waste. To improve the processing quality of profile rolling forming technology, the influence of profile thickness, rolling processing speed, and friction coefficient on profile forming curvature and forming quality were quantitatively analyzed. The grey relational analysis method was used to comprehensively analyze the influence of various factors on the profile during the rolling process, and the optimal processing conditions for the profile could be obtained through analysis, providing a new experimental method for the research of profile rolling forming.

In a powder bed fusion (PBF) process where powder bed preheating is needed, the powder bed will be subjected to an aging issue, which limits the reuse of powders. In response to the powder aging issue and to recycle powders, extensive attention has been attracted to study powder aging mechanisms in PBF to explore potential solutions. In this investigation, we have studied the aging mechanisms and proposed an epoxy resin solution (EP) infiltration method to mitigate side effects of powder aging in PBF-sintered nylon12 (PA12) specimens. Particularly, a comprehensive study on effects of powder recycling, building directions, and EP infiltration on microstructure characterizations, part quality, as well as thermal and mechanical properties of PBF-sintered PA12 specimens has been presented, for the first time. The quantitative relationships between sintering window width and warpage degree have been developed. A finite element analysis method has been utilized to learn stress distribution and concentration in PBF-sintered PA12 specimens and to predict fracture features. An insight into the strengthening effects induced by the EP infiltration at an atomic level has been provided by conducting molecular dynamic simulations.

Despite their high strengths and moduli, the inherent brittleness of ceramics restricts their ability to resist fracture upon impact. Designing special structures can toughen ceramics and expand their application realm; however, the ceramic strength is sacrificed. To address this problem, a damage-resistant ceramic process involving both interior and exterior strengthening and toughening is proposed. In this method, a buried combustion method (BCM) was implemented while debinding alumina (Al2O3) green bodies, and a coating method (CM) was used after sintering Al2O3parts. Experimental results show that an increase of 259% in ultimate compressive stress and an increase of 161% in energy absorption compared with untreated Al2O3parts were achieved by adopting the BCM and CM methods. In addition, a finite-element modeling method was used to study fracture mechanisms, and molecular dynamic simulations were implemented to provide insight into the strengthening and toughening mechanisms at the atomic level.

β-Carboline (βC) alkaloids constitute a large family of indole alkaloids that exhibit diverse pharmacological properties, such as antitumor, antiviral, antiparasitic, and antimicrobial activities. Here, we report that a flavoprotein StnP2 catalyzes the dehydrogenation at C1–N2 of a tetrahydro-β-carboline (THβC) generating a 3,4-dihydro-β-carboline (DHβC), and the DHβC subsequently undergoes a spontaneous dehydrogenation to βC formation involved in the biosynthesis of the antitumor agent streptonigrin. Biochemical characterization showed that StnP2 catalyzed the highly regio- and stereo-selective dehydrogenation, and StnP2 exhibits promiscuity toward different THβCs. This study provides an alternative kind of enzyme catalyzing the biosynthesis of βC alkaloids and enhances the importance of flavoproteins.