Reflections of a conceptualist
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Exploring the potential of LLM to enhance teaching plans through teaching simulation
The introduction of large language models (LLMs) may change future pedagogical practices. Current research mainly focuses on the use of LLMs to tutor students, while the exploration of LLMs’ potential to assist teachers is limited. Taking high school mathematics as an example, we propose a method that utilizes LLMs to enhance the quality of teaching plans through guiding the LLM to simulate teacher-student interactions, generate teaching reflections, and subsequently direct the LLM to refine the teaching plan by integrating these teaching process and reflections. Human evaluation results show that this method significantly elevates the quality of the original teaching plans generated directly by LLM. The improved teaching plans are comparable to high-quality ones crafted by human teachers across various assessment dimensions and knowledge modules. This approach provides a pre-class rehearsal simulation and ideas for teaching plan refinement, offering practical evidence for the widespread application of LLMs in teaching preparation.
Discovery of giant unit-cell super-structure in the infinite-layer nickelate PrNiO2+x
The discovery of unconventional superconductivity often triggers significant interest in associated electronic and structural symmetry breaking phenomena. For the infinite-layer nickelates, structural allotropes are investigated intensively. Here, using high-energy grazing-incidence x-ray diffraction, we demonstrate how in-situ temperature annealing of the infinite-layer nickelate PrNiO2+x (x ≈ 0) induces a giant superlattice structure. The annealing effect has a maximum well above room temperature. By covering a large scattering volume, we show a rare period-six in-plane (bi-axial) symmetry and a period-four symmetry in the out-of-plane direction. This giant unit-cell superstructure—likely stemming from ordering of diffusive oxygen—persists over a large temperature range and can be quenched. As such, the stability and controlled annealing process leading to the formation of this superlattice structure provides a pathway for novel nickelate chemistry.
High-pressure synthesis and crystal structure of iron sp3-carbonate (Fe2[C4O10]) featuring pyramidal [C4O10]4- anions
The behavior of iron carbonates at high pressures is relevant for geological processes occurring in Earth interiors. Here, cubic iron sp3-carbonate Fe2[C4O10] was synthesized in diamond anvil cell by reacting Fe2O3 and CO2 at 65(4) GPa and 3000(±500) K, simulating the environment of localized thermal anomalies in the mantle. The crystal structure, determined by in situ single-crystal X-ray diffraction, features pyramidal [C4O10]4- anions. The experimental crystal structure corresponds to a structural model from density functional theory calculations. Experimentally determined values for zero-pressure volume V0 and bulk modulus K0 are: V0 = 1059(17) Å3, K0 = 160(18) GPa, The DFT-calculated Raman spectrum, modeled with zinc substituting iron, matches the experimental one, supporting the structural model’s accuracy. Fe2[C4O10] remained stable upon decompression down to 25 GPa, below which it amorphized. DFT calculations also reveal a spin crossover of Fe2+ cations at 95 GPa, which is significantly higher than in other Fe2+-containing carbonates.
Modulation of the electromagnetic shielding effectiveness through micro/macrostructure design for electronic packaging
Lightweight electronic packaging that provides mechanical protection, cooling ability, and customizable electromagnetic interference (EMI) shielding effectiveness (SE) is needed for next-generation electronics. Although electronic packaging solutions with excellent EMI SE exist, there is limited research on how hierarchical design can modulate the EMI SE of an electronic packaging material on demand. In this study, the deliberate precise micro/macrostructure design of graphite-based materials using magnetically assisted 3D printing allows tuning of the EMI SE in the X band (8–12 GHz), leading to a maximum total shielding performance of 90 dB. Aligning high-density graphite microplatelets during 3D printing also remarkably amplified the total SE by 200%. Subsequently, rationally designing the oriented microstructure within a geometrical shape increases the reflection and improves the EMI SE from 40 to 60 dB in a specific direction. Our proof-of-concept samples demonstrate the potential of precise micro/macrostructure design for customizing and enhancing electronic packaging’s EMI SE while achieving good heat dissipation and mechanical protection using a versatile 3D printing method. These advances pave the way for more reliable and safer electronic systems.
Mixed polytype/polymorph formation in InSe films grown by molecular beam epitaxy on GaAs(111)B
We report the growth of InSe films on semi-insulating GaAs(111)B substrates by molecular beam epitaxy (MBE). Excellent nucleation behavior resulted in the growth of smooth, single-phase InSe films. The dominant polytype was the targeted γ-InSe. Transmission electron microscopy revealed the presence of three bulk polytypes β, γ, and ε-InSe arranged in nanosized domains, which can be interpreted as sequences of stacking faults and rotational twin boundaries of γ-InSe. Additionally, a centrosymmetric Se-In-In-Se layer polymorph with (Pbar{3}m) symmetry was identified as typically not present in bulk. Sizeable differences in their electronic properties were found, which resulted in sizeable electronic disorder arising from the nanoscale polytype arrangement that dominated the electronic transport properties. While MBE is a viable synthesis route towards stabilization of InSe polytypes not present in the bulk, an improved understanding to form the targeted polymorph is required to ultimately inscribe a layer sequence on demand utilizing bottom-up synthesis approaches.
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