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Thermoelectric power generation offers a promising way to recover waste heat. The geometrical design of thermoelectric legs in modules is important to ensure sustainable power generation but cannot be easily achieved by traditional fabrication processes. Herein, we propose the design of cellular thermoelectric architectures for efficient and durable power generation, realized by the extrusion-based 3D printing process of Cu 2 Se thermoelectric materials. We design the optimum aspect ratio of a cuboid thermoelectric leg to maximize the power output and extend this design to the mechanically stiff cellular architectures of hollow hexagonal column- and honeycomb-based thermoelectric legs. Moreover, we develop organic binder-free Cu 2 Se-based 3D-printing inks with desirable viscoelasticity, tailored with an additive of inorganic Se 8 2− polyanion, fabricating the designed topologies. The computational simulation and experimental measurement demonstrate the superior power output and mechanical stiffness of the proposed cellular thermoelectric architectures to other designs, unveiling the importance of topological designs of thermoelectric legs toward higher power and longer durability. The geometrical design of thermoelectric legs in modules is key for sustainable power generation but can be hardly achieved by traditional fabrication process. Here, the authors develop an extrusion-based 3D printing process of Cu2Se thermoelectric materials for efficient power generation.

Brain organoids derived from human pluripotent stem cells provide a highly valuable in vitro model to recapitulate human brain development and neurological diseases. However, the current systems for brain organoid culture require further improvement for the reliable production of high-quality organoids. Here, we demonstrate two engineering elements to improve human brain organoid culture, (1) a human brain extracellular matrix to provide brain-specific cues and (2) a microfluidic device with periodic flow to improve the survival and reduce the variability of organoids. A three-dimensional culture modified with brain extracellular matrix significantly enhanced neurogenesis in developing brain organoids from human induced pluripotent stem cells. Cortical layer development, volumetric augmentation, and electrophysiological function of human brain organoids were further improved in a reproducible manner by dynamic culture in microfluidic chamber devices. Our engineering concept of reconstituting brain-mimetic microenvironments facilitates the development of a reliable culture platform for brain organoids, enabling effective modeling and drug development for human brain diseases. Brain organoids derived from human pluripotent stem cells can model human brain development and disease, though current culture systems fail to ensure reliable production of high-quality organoids. Here the authors combine human brain extracellular matrix and culture in a microfluidic device to promote structural and functional maturation of human brain organoids.

Decrease in processing speed due to increased resistance and capacitance delay is a major obstacle for the down-scaling of electronics 1 – 3 . Minimizing the dimensions of interconnects (metal wires that connect different electronic components on a chip) is crucial for the miniaturization of devices. Interconnects are isolated from each other by non-conducting (dielectric) layers. So far, research has mostly focused on decreasing the resistance of scaled interconnects because integration of dielectrics using low-temperature deposition processes compatible with complementary metal–oxide–semiconductors is technically challenging. Interconnect isolation materials must have low relative dielectric constants ( κ values), serve as diffusion barriers against the migration of metal into semiconductors, and be thermally, chemically and mechanically stable. Specifically, the International Roadmap for Devices and Systems recommends 4 the development of dielectrics with κ values of less than 2 by 2028. Existing low- κ materials (such as silicon oxide derivatives, organic compounds and aerogels) have κ values greater than 2 and poor thermo-mechanical properties 5 . Here we report three-nanometre-thick amorphous boron nitride films with ultralow κ values of 1.78 and 1.16 (close to that of air, κ = 1) at operation frequencies of 100 kilohertz and 1 megahertz, respectively. The films are mechanically and electrically robust, with a breakdown strength of 7.3 megavolts per centimetre, which exceeds requirements. Cross-sectional imaging reveals that amorphous boron nitride prevents the diffusion of cobalt atoms into silicon under very harsh conditions, in contrast to reference barriers. Our results demonstrate that amorphous boron nitride has excellent low- κ dielectric characteristics for high-performance electronics. Thin films of amorphous boron nitride are mechanically and electrically robust, prevent diffusion of metal atoms into semiconductors and have ultralow dielectric constants that exceed current recommendations for high-performance electronics.

Background/objectives: This study aims to identify the effects of cognitive and emotional variables related to immersive virtual reality media technology on learning for nursing students. Methods/Statistical analysis: The subjects of this study were 121 nursing students from a university in area D. After experiential learning with virtual reality from 6–8 June 2019, data was collected through questionnaires. For virtual reality learning, VIVE’s hTC VIVE ECO CE model was used. The collected data was analyzed using the IBM SPSS 26.0 program. Multiple Regression Analysis was used to analyze the factors influencing the subject’s virtual reality learning effects. Findings: The learning effects of the virtual reality medium had a statistically significant positive correlation with the virtual reality technology recognition, sensory immersion, realism, learning satisfaction, learning necessity, and continuous use intention (p < 0.001) scores. In personality traits, only Openness, Extraversion (p < 0.01), and Conscientiousness (p < 0.05) had a statistically significant positive correlation. As a result of regression analysis, the explanatory power of the learning effect of the virtual reality medium was 63.9% (F = 53.61, p < 0.001), with learning satisfaction, sensory immersion, continuous use intention, and Extraversion being significant influencing factors (p < 0.05). Improvements/Applications: This study is meaningful in the sense that it provided strategic implications for the teaching and learning method of virtual reality technology-based learning by considering the insights necessary to develop a learning program using virtual reality technology, according to the characteristics of virtual reality technology, and the learner’s cognitive and psychological variables.

Ischemic stroke is one of the leading causes of death, and even timely treatment can result in severe disabilities. Reperfusion of the ischemic stroke region and restoration of the blood supply often lead to a series of cellular and biochemical consequences, including generation of reactive oxygen species (ROS), expression of inflammatory cytokines, inflammation, and cerebral cell damage, which is collectively called cerebral ischemia-reperfusion (IR) injury. Since ROS and inflammatory cytokines are involved in cerebral IR injury, injury could involve cellular senescence. Thus, we investigated whether senolytic therapy that eliminates senescent cells could be an effective treatment for cerebral IR injury. To determine whether IR induces neural cell senescence in vitro, astrocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). OGD/R induced astrocyte senescence and senescent cells in OGD/R-injured astrocytes were effectively eliminated in vitro by ABT263, a senolytic agent. IR in rats with intraluminal middle cerebral artery occlusion induced cellular senescence in the ischemic region. The senescent cells in IR-injured rats were effectively eliminated by intravenous injections of ABT263. Importantly, ABT263 treatment significantly reduced the infarct volume and improved neurological function in behavioral tests. This study demonstrated, for the first time, that senolytic therapy has therapeutic potential for cerebral IR injury.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening diseases; however, it is hard to estimate their incidence due to the rarity of these diseases. We evaluated the incidence of SJS and TEN using a nationwide administrative database. We used a national medical insurance review system (Health Insurance Review and Assessment) database which contained the claim data of the entire nation from 2009 to 2013 to estimate the accurate incidence of SJS and TEN in Korea. The diagnostic codes of L511 (SJS) or L512 (TEN) from the International Classification of Diseases-10th revision were used to define the target study population. We also retrospectively followed up a 2011 SJS and TEN cohort for 24 months in order to assess the in-hospital mortality, related complications and total claims cost due to SJS and TEN. A total of 1,167 (938 SJS and 229 TEN) cases were newly diagnosed from 2010 to 2013. The age- and sex-standardized annual incidences estimated in this study were 3.96 to 5.03 in SJS and 0.94 to 1.45 in TEN per million. There was no significant change in annual incidence throughout the study periods. When analyzed by 10-year age groups, the annual incidence was the lowest in group 20-29 years and the highest in group 70 for both SJS and TEN. Based on the 2011 cohort analysis, the in-hospital mortality were 5.7 and 15.1% for SJS and TEN, respectively. The mortality increased with age, particularly, after 40 years of age. Among the complications related with SJS or TEN, ocular sequelae was the most common (43.1 and 43.4% of SJS and TEN patients, respectively) followed by urethral sequelae (5.7 and 9.4% of SJS and TEN patients, respectively). Overall, our data suggest that SJS, and TEN are infrequent but constantly arise throughout the years.

Current soft neural probes are still operated by bulky, rigid electronics mounted to a body, which deteriorate the integrity of the device to biological systems and restrict the free behavior of a subject. We report a soft, conformable neural interface system that can monitor the single-unit activities of neurons with long-term stability. The system implements soft neural probes in the brain, and their subsidiary electronics which are directly printed on the cranial surface. The high-resolution printing of liquid metals forms soft neural probes with a cellular-scale diameter and adaptable lengths. Also, the printing of liquid metal-based circuits and interconnections along the curvature of the cranium enables the conformal integration of electronics to the body, and the cranial circuit delivers neural signals to a smartphone wirelessly. In the in-vivo studies using mice, the system demonstrates long-term recording (33 weeks) of neural activities in arbitrary brain regions. In T-maze behavioral tests, the system shows the behavior-induced activation of neurons in multiple brain regions. Neural systems are often bulky and heavy. Here, the authors produce a conformable neural interface for mice using liquid metals directly printed on the skull that can monitor neural activities with long-term stability.

To comprehend the volumetric neural connectivity of a brain organoid, it is crucial to monitor the spatiotemporal electrophysiological signals within the organoid, known as intra-organoid signals. However, previous methods risked damaging the three-dimensional (3D) cytoarchitecture of organoids, either through sectioning or inserting rigid needle-like electrodes. Also, the limited numbers of electrodes in fixed positions with non-adjustable electrode shapes were insufficient for examining the complex neural activity throughout the organoid. Herein, we present a magnetically reshapable 3D multi-electrode array (MEA) using direct printing of liquid metals for electrophysiological analysis of brain organoids. The adaptable distribution and the softness of these printed electrodes facilitate the spatiotemporal recording of intra-organoid signals. Furthermore, the unique capability to reshape these soft electrodes within the organoid using magnetic fields allows a single electrode in the MEA to record from multiple points, effectively increasing the recording site density without the need for additional electrodes. Conventional platforms for electrophysiological recording of organoids have limited recording site density. Here, the authors present the magnetically reshapable 3D liquid metal-based electrode array for high-resolution analysis on neural activities of brain organoids.

Integrated electronic circuitries with pressure sensors have been extensively researched as a key component for emerging electronics applications such as electronic skins and health-monitoring devices. Although existing pressure sensors display high sensitivities, they can only be used for specific purposes due to the narrow range of detectable pressure (under tens of kPa) and the difficulty of forming highly integrated arrays. However, it is essential to develop tactile pressure sensors with a wide pressure range in order to use them for diverse application areas including medical diagnosis, robotics or automotive electronics. Here we report an unconventional approach for fabricating fully integrated active-matrix arrays of pressure-sensitive graphene transistors with air-dielectric layers simply formed by folding two opposing panels. Furthermore, this realizes a wide tactile pressure sensing range from 250 Pa to ∼3 MPa. Additionally, fabrication of pressure sensor arrays and transparent pressure sensors are demonstrated, suggesting their substantial promise as next-generation electronics. Electronic skins and health monitoring devices rely on integrated tactile sensors, which often require tailored degrees of sensitivity in specific pressure ranges. Here, the authors fabricate a versatile matrix array of pressure-sensitive graphene transistors operating in the wide 250 Pa to 3 MPa pressure range.

The aim of this review was to examine how debriefings have been conducted in healthcare simulations. Using keywords, our search yielded 962 studies through databases. After removing duplicates, we found 20 studies that met inclusion and exclusion criteria. Through ancestry searches, we found two more studies. A total of 22 studies were reviewed. From each study, detailed information about debriefing was extracted based on six criteria, namely, timing, facilitator, place of occurrence, method, length, and structure. Various types of debriefings were available according to learning objectives, learners’ abilities, availability of resources, and context of simulations. We found that peer-led debriefing might be more appropriate for experienced healthcare professionals than unlicensed students due to a gap in knowledge and problem-solving skills between them. In addition, we found that tele-debriefing was feasible in some studies. Although types of individual debriefing varied across the studies, a substantial number of debriefings closely aligned to the standards for high-quality debriefing. •There is no absolute way to do the best debriefing.•Self-led and peer-led debriefings can be effective when learners have enough ability to reflect and criticize by themselves.•Learners can have rich and informative simulation learning when various methods were used for debriefing.•Structured debriefing allows learners to reflect on their performance in a psychologically safe environment.