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Halide perovskites, fascinating memristive materials owing to mixed ionic-electronic conductivity, have been attracting great attention as artificial synapses recently. However, polycrystalline nature in thin film form and instability under ambient air hamper them to be implemented in demonstrating reliable neuromorphic devices. Here, we successfully fabricated vertically aligned 2D halide perovskite films (V-HPs) for active layers of artificial synapses, showing moisture stability for several months. Unlike random-oriented HPs, which exhibit negligible current hysteresis, the V-HPs possess multilevel analog memristive characteristics, programmable potentiation and depression with distinguished multi-states, long-short-term plasticity, paired-pulse facilitation, and even spike-timing-dependent plasticity. Furthermore, high classification accuracy is obtained with implementation in deep neural networks. These remarkable improvements are attributed to the vertically well-aligned lead iodide octahedra acting as the ion transport channel, confirmed by first-principles calculations. This study paves the way for understanding HPs nanophysics and demonstrating their potential utility in neuromorphic computing systems.

Purpose The aim of this study was to evaluate the feasibility and satisfaction of an online global health education course for medical students in comparison with an in-person of the course and to assess students' preferences regarding online methods of delivery. Methods Second-year medical students enrolled in this course in 2019 (in-person) and 2020 (online). The attendance rate, satisfaction in the course evaluation survey, and academic achievement on the written final examination were utilized to compare the two different methods of course delivery. The medical students who took the online course were also asked about their preferences regarding the method of course delivery and the advantages and drawbacks of each method of online lectures. Results There was no significant difference in the attendance rate and overall satisfaction between the two groups. The mean score on the written examination of the online course (84.1±19.6) showed comparable effects to the in-person course (78.0±18.3). The percentages of students who achieved high performance (55.5%) and the achieved minimum requirement (95.9%) were also maintained compared to the in-person course (14.6% and 93.6%, respectively). Medical students preferred the online course to the in-person course; in particular, they preferred prerecorded videos over live streaming online lectures. Conclusion The participation, satisfaction, and the academic achievement of the online course were comparable to those of the in-person course. However, the greatest drawback of the online course was the lack of interaction between peer learners. Therefore, diverse methods for online education should be considered to increase students' sense of belonging to a learning community.

Increasing the growth rate of thin films and enhancing the film quality have been an issue in the semiconductor manufacturing process. To improve those properties, conventionally the deposition temperature in reactor was increased or a catalyst was added to decompose precursors at low temperature. Here, a new technology utilizing a bipolar carbon fiber ionizer (CFI) was used to achieve a high growth rate and quality of silicon films. The deposition behavior of atmospheric pressure chemical vapor deposition silicon films deposited with and without the bipolar CFI system was compared. The growth rate of silicon films deposited at 450 °C, 500 °C, 700 °C, 900 °C and 1100 °C with the bipolar CFI system was 3.4, 5.6, 3.2, 3.3 and 1.3 times higher than deposited silicon film without the bipolar CFI system. The bipolar CFI system could also improve the crystallinity of the silicon film deposited at 900 °C.

Organometallic and all-inorganic halide perovskites (HPs) have recently emerged as promising candidate materials for resistive switching (RS) nonvolatile memory due to their current-voltage hysteresis caused by fast ion migration. Lead-free and all-inorganic HPs have been researched for non-toxic and environmentally friendly RS memory devices. However, only HP-based devices with electrochemically active top electrode (TE) exhibit ultra-low operating voltages and high on/off ratio RS properties. The active TE easily reacts to halide ions in HP films, and the devices have a low device durability. Herein, RS memory devices based on an air-stable lead-free all-inorganic dual-phase HP (AgBi2 I7 -Cs3 Bi2 I9 ) are successfully fabricated with inert metal electrodes. The devices with Au TE show filamentary RS behavior by conducting-bridge involving Ag cations in HPs with ultra-low operating voltages ( 107 ), multilevel data storage, and long retention times (>5 × 104 s). The use of a closed-loop pulse switching method improves reversible RS properties up to 103 cycles with high on/off ratio above 106 . With an extremely small bending radius of 1 mm, the devices are operable with reasonable RS characteristics. This work provides a promising material strategy for lead-free all-inorganic HP-based nonvolatile memory devices for practical applications.

Fresh concrete used in 3D printing should ensure adequate yield stress, otherwise the printed concrete layer may suffer intolerable deformation or collapse during the printing process. In response to this issue, an analytical study was carried out to derive the initial yield stress and hardening coefficient of fresh concrete suitable for 3D printing. The maximum shear stress distribution of fresh concrete was calculated using a stress transformation equation derived from the equilibrium condition of forces. In addition, the elapsed time experienced by fresh concrete during the printing processes was estimated and was then substituted into the elapsed time-yield stress function to calculate the yield stress distribution. Based on these results, an algorithm capable of deriving both the initial yield stress and the hardening coefficient required for printing fresh concrete up to the target height was proposed and computational fluid dynamics (CFD) analyses were performed to verify the accuracy of the proposed model.

Host immune response is known to contribute to the progression of periodontitis, and alveolar bone destruction in periodontitis is associated with enhanced osteoclast activity. Therefore, we evaluated the roles of activated lymphocyte subsets in osteoclastogenesis. Osteoclast precursors were co-cultured with activated lymphocytes (B, CD4(+) T, CD8(+) T) in the presence of either macrophage colony-stimulating factor (M-CSF) alone or M-CSF plus soluble receptor activator of NF-kappaB ligand (sRANKL), and subsequent differentiation into active osteoclasts was evaluated by a resorption assay. The activated B and CD4(+) cells, but not CD8(+) T cells, induced osteoclast differentiation in the presence of M-CSF alone. In the presence of M-CSF and sRANKL, B cells induced the formation of small but highly active osteoclasts and increased resorption, while CD8(+) T cells profoundly suppressed osteoclastogenesis. Co-culture using an insert well or supernatant suggested that both B and CD8(+) T cells acted on osteoclasts mostly via soluble proteins. Activated B cells expressed many osteoclastogenic factors including RANKL, TNF-alpha, IL-6, MIP-1alpha, and MCP-3. CD8(+) T cells expressed a substantial amount of osteoprotegerin (OPG) along with RANKL. However, blocking antibody to OPG did not reverse the suppression by CD8(+) T cells, suggesting that other factor(s) are involved. Taken together, activated B cells promoted osteoclastogenesis, while CD8(+) T cells inhibited the osteoclast formation via direct interaction. The results imply the importance of lymphocyte subpopulations in the development of periodontitis.

Aims and objectives Methods and materials Results Conclusion Personal information References, Aims and objectives: Susceptibility weighted imaging (SWI) can exploit the magnetic susceptibility differences of various tissues. SWI is more sensitive in detection of susceptibility effects and depicts significantly more small hemorrhagic lesions than does the...