Abstract: The Birch reduction, a classic method involving the partial reduction of aromatic rings using alkali metals in liquid ammonia, has played a pivotal role in the development of modern organic synthesis. This transformation enables the regioselective generation of substituted cyclohexa-1, 4- and 1, 3-dienes-particularly enol ethers-from benzene derivatives, offering unique access to synthetically valuable intermediates. Historically, it was the only viable route to such non-conjugated dienes, and its absence would have significantly delayed the synthesis of key bioactive molecules, including 19-norsteroids and early oral contraceptives. The reaction provides exceptional steric and electronic control, facilitating downstream transformations such as Diels-Alder cycloadditions, reductive alkylations, and stereoselective functionalizations. Furthermore, the integration of Birch-derived intermediates with organometallic chemistry-particularly Fe(CO)3 complexation-introduces facial differentiation, enabling enantioselective synthesis through "inorganic enzyme chemistry." This review highlights the mechanistic principles of the Birch reduction, its role in the synthesis of natural products such as mycophenolic acid, nootkatone, juvabione, gabaculine, and shikimic acid, and its evolving applications in stereocontrolled synthesis. The enduring utility of this method underscores its importance in both fundamental and applied organic chemistry. Read More

Abstract: Die-cast alloys, such as aluminum, zinc, and magnesium alloys, are widely used in automotive, aerospace, and consumer electronics applications due to their excellent mechanical properties, castability, and cost-effectiveness. Fracture failure, however, remains a critical concern, directly affecting performance and service life. This review summarizes current advances in fracture prediction for die-cast alloys, including common alloy types, fracture mechanisms, failure modes, influencing factors, and predictive models. Key studies are cited to highlight the coupled effects of microstructural defects, stress state, and temperature on fracture behavior, and the applicability and limitations of models such as GISSMO and MMC are discussed. Future research directions are also outlined. Read More

Abstract: This paper reviews the development, preparation methods, and strengthening mechanisms of high-entropy alloys (HEAs). Different from traditional alloys, HEAs contain at least five principal elements and show severe lattice distortion and chemical short-range order. These features give HEAs special mechanical properties. The article first introduces the background and research status of HEAs, especially the AlCoCrFeNi system. Then, it summarizes common preparation methods, such as vacuum melting, powder metallurgy, laser cladding, and high-temperature high-pressure sintering. After that, it discusses five main strengthening mechanisms: second-phase strengthening, work hardening, grain refinement, heterostructure strengthening, and solid-solution strengthening (substitutional and interstitial). Finally, it points out that the interstitial strengthening mechanism is still unclear, and more work is needed on composition design, heat treatment, and the cooperation among different strengthening methods. Further study on HEAs will provide new ideas for designing high-performance materials. Read More

Abstract: This paper presents a systematic review and synthesis of the field of luminescent rare earth complexes, highlighting landmark research advances achieved over the past decades and offering perspectives on future research priorities and application scenarios for these materials. Luminescent rare earth complexes are poised to continue playing a pivotal role in driving technological innovation and promoting sustainable development on a global scale. Against this backdrop, and drawing on recently published literature and experimental data, this study systematically organizes and summarizes research progress in luminescent rare earth complexes, with the aim of providing a valuable reference for ongoing investigations in this field. Read More

Abstract: Inlays, as a conservative and aesthetic oral restoration method, have gradually replaced traditional fillings in the treatment of moderate to large dental defects due to their superior marginal adaptability, mechanical stability, and aesthetic performance. Material science is the core driving force for the development of inlay technology, and the performance optimization of traditional materials and the emergence of new materials have continuously expanded the clinical application scope of inlays. This systematic review summarizes the latest progress in the material science of oral restoration inlays, focusing on the performance improvement of classic materials (resin, ceramic, metal), the development of composite materials, and the application of functional materials. We also analyze the clinical selection strategies of inlay materials and future development directions to provide evidence-based references for oral restoration practice. A comprehensive literature search was conducted in PubMed, Embase, and Cochrane Library using keywords including "inlay material", "oral restoration", "ceramic inlay", and "resin composite inlay". Relevant studies published between 2018 and 2025 were included, and the final analysis covered 40 high-quality articles (randomized controlled trials, systematic reviews, and laboratory studies). Read More

Abstract: The Birch reduction, a classical organic transformation discovered by Arthur J. Birch in 1944, remains a powerful and indispensable tool for the partial reduction of aromatic compounds. This review delves into the mechanistic underpinnings of the reaction, emphasizing its predictable regioselectivity governed by substituent effects. Its principal focus is on showcasing the strategic application of the Birch reduction as a key step in the total synthesis of complex natural products. Several case studies are examined, including syntheses of steroids, terpenoids, and alkaloids, highlighting how Birch-derived intermediates enable the efficient construction of intricate molecular architectures. Furthermore, the integration of this classic method with modern organometallic and pericyclic reactions is discussed, underscoring its enduring relevance and evolving potential in synthetic organic chemistry. This review systematically examines the mechanistic principles underlying this transformation, with particular emphasis on its well-defined regioselectivity—a predictable outcome governed by the electronic nature of aromatic substituents through resonance and inductive effects. The central focus of this discussion lies in elucidating the strategic implementation of Birch reduction as a pivotal disconnection in the total synthesis of structurally complex natural products. Through representative case studies encompassing steroids, terpenoids, and alkaloids, we demonstrate how Birch-derived diene and enol ether intermediates serve as key building blocks for the efficient and stereo controlled assembly of intricate molecular architectures. Furthermore, this analysis explores the productive integration of this classical protocol with contemporary synthetic strategies, including transition metal-mediated transformations and concerted pericyclic processes, thereby highlighting its enduring relevance and continuing evolution as a fundamental tool in modern synthetic organic … Read More