ABSTRACT This study proposes a strategy to simultaneously improve conductance uniformity and data retention characteristics by introducing the incremental step pulse with verify algorithm (ISPVA) technique and hydrogen (H 2 ) annealing into a non‐filamentary TiN/Ti/HfO 2 /TiO x /TiN resistive switching memory device. The high Schottky barrier formed at the Ti/HfO 2 interface induces asymmetric electron injection and limits reverse current flow, resulting in a rectifying ratio of approximately 1442. This self‐rectifying characteristic provides an intrinsic advantage in suppressing sneak currents in crossbar arrays. The ISPVA technique improves the linearity and uniformity of conductance modulation, enabling the implementation of up to 6‐bit multilevel states within a few‐µA current range. In addition, H 2 annealing stabilized conduction by forming hydrogen bonds with oxygen vacancies in the oxide layer and suppressing oxygen ion–vacancy recombination. As a result, data retention over 10 4 s and endurance exceeding 10 4 cycles were achieved even under a low energy consumption of 36.3 pJ. Furthermore, the experimentally obtained long‐term potentiation and depression characteristics were implemented in a Transformer‐based keyword spotting (KWS) model, achieving a recognition accuracy of 92.5%. These results suggest that the proposed device enables controlled analog conductance modulation with improved stability, showing its potential for Transformer‐based neuromorphic computing applications.

Abstract This study implements a highly uniform 3D vertically stack resistive random‐access memory (VRRAM) with a four‐layer contact hole structure. The fabrication process of a four‐layer VRRAM is demonstrated, and its physical and electrical properties are thoroughly examined. X‐ray photoelectron spectroscopy and transmission electron microscopy are employed to analyze the chemical distribution and physical structure of the VRRAM device. Multilevel capability, reliable endurance (>10 4 cycles), and retention (10 4 s) are successfully obtained. Synaptic memory plasticity, such as spike time‐dependent plasticity, spike rate‐dependent plasticity, excitatory post‐synaptic current, paired‐pulse facilitation, and long‐term potentiation and depression is presented. Finally, the vector‐matrix multiplication (VMM) operation is conducted on a 4 × 12 VRRAM array, according to the low resistance state ratio. It is ascertained that the accuracy drop, which can occur due to VMM error, can be limited to a decrease of less than 0.44% point. Utilizing the high‐density, multilevel, and biological characteristics of VRRAM, it is possible to implement high‐performance neuromorphic systems that require densely integrated synaptic devices.

ABSTRACT This study proposes a strategy to simultaneously improve conductance uniformity and data retention characteristics by introducing the incremental step pulse with verify algorithm (ISPVA) technique and hydrogen (H 2 ) annealing into a non‐filamentary TiN/Ti/HfO 2 /TiO x /TiN resistive switching memory device. The high Schottky barrier formed at the Ti/HfO 2 interface induces asymmetric electron injection and limits reverse current flow, resulting in a rectifying ratio of approximately 1442. This self‐rectifying characteristic provides an intrinsic advantage in suppressing sneak currents in crossbar arrays. The ISPVA technique improves the linearity and uniformity of conductance modulation, enabling the implementation of up to 6‐bit multilevel states within a few‐µA current range. In addition, H 2 annealing stabilized conduction by forming hydrogen bonds with oxygen vacancies in the oxide layer and suppressing oxygen ion–vacancy recombination. As a result, data retention over 10 4 s and endurance exceeding 10 4 cycles were achieved even under a low energy consumption of 36.3 pJ. Furthermore, the experimentally obtained long‐term potentiation and depression characteristics were implemented in a Transformer‐based keyword spotting (KWS) model, achieving a recognition accuracy of 92.5%. These results suggest that the proposed device enables controlled analog conductance modulation with improved stability, showing its potential for Transformer‐based neuromorphic computing applications.

Abstract This study implements a highly uniform 3D vertically stack resistive random‐access memory (VRRAM) with a four‐layer contact hole structure. The fabrication process of a four‐layer VRRAM is demonstrated, and its physical and electrical properties are thoroughly examined. X‐ray photoelectron spectroscopy and transmission electron microscopy are employed to analyze the chemical distribution and physical structure of the VRRAM device. Multilevel capability, reliable endurance (>10 4 cycles), and retention (10 4 s) are successfully obtained. Synaptic memory plasticity, such as spike time‐dependent plasticity, spike rate‐dependent plasticity, excitatory post‐synaptic current, paired‐pulse facilitation, and long‐term potentiation and depression is presented. Finally, the vector‐matrix multiplication (VMM) operation is conducted on a 4 × 12 VRRAM array, according to the low resistance state ratio. It is ascertained that the accuracy drop, which can occur due to VMM error, can be limited to a decrease of less than 0.44% point. Utilizing the high‐density, multilevel, and biological characteristics of VRRAM, it is possible to implement high‐performance neuromorphic systems that require densely integrated synaptic devices.

The progress of brain synaptic devices has witnessed an era of rapid and explosive growth. Because of their integrated storage, excellent plasticity and parallel computing, and system information processing abilities, various field effect transistors have been used to replicate the synapses of a human brain. Organic semiconductors are characterized by simplicity of processing, mechanical flexibility, low cost, biocompatibility, and flexibility, making them the most promising materials for implanted brain synaptic bioelectronics. Despite being used in numerous intelligent integrated circuits and implantable neural linkages with multiple terminals, organic synaptic transistors still face many obstacles that must be overcome to advance their development. A comprehensive review would be an excellent tool in this respect. Therefore, the latest advancements in implantable neural links based on organic synaptic transistors are outlined. First, the distinction between conventional and synaptic transistors are highlighted. Next, the existing implanted organic synaptic transistors and their applicability to the brain as a neural link are summarized. Finally, the potential research directions are discussed.

Background Alterations in the ionic microenvironment and interstitial fluid (ISF) dynamics are increasingly recognized as early pathological events in Alzheimer’s disease (AD). However, the in vivo relationship between bulk tissue electrical properties and ISF mobility remains unclear. Purpose This study aimed to investigate the relationship between magnetic resonance electrical properties tomography (MREPT)-derived high-frequency conductivity (HFC) and intravoxel incoherent motion (IVIM)-derived ISF-related metrics in patients with cognitive impairments across the cognitively normal to AD spectrum. Methods A total of 161 participants (26 cognitively normal (CN), 78 with amnestic mild cognitive impairment (MCI), and 57 with AD) underwent 3.0 T MRI. HFC maps were reconstructed using phase-based MREPT. ISF-related diffusion (D ISF ) and volume fraction (F ISF ) indices were extracted from multi-b-value IVIM data using an unsupervised physics-informed neural network (PINN) approach. Voxel-based and region-of-interest (ROI) statistical analyses, including ANCOVA, partial correlations, and robust multiple regressions, were performed with adjustments for age and sex. Results Along the disease progression from CN to AD, D ISF significantly decreased, while F ISF and HFC increased. Partial correlation analyses revealed that these alterations were significantly correlated with age and cognitive decline. Furthermore, MREPT-derived HFC exhibited region-specific correlations with IVIM-derived ISF-related measures, most notably in the bilateral corpus callosum and thalamus. Robust multiple regression analyses revealed limited, region-specific independent associations between ISF indices and HFC, with the most robust finding observed for D ISF in the left thalamus, whereas F ISF -related associations did not survive correction, and F PAR showed the most consistent independent association in the volume-fraction model. Conclusion The region-specific associations observed between MREPT-derived HFC and IVIM-derived ISF-related metrics in select AD-vulnerable regions, particularly the independent D ISF –HFC association in the left thalamus, suggest that neurodegeneration may be linked with local ionic and microenvironmental compartmental shifts. These findings require replication in larger, independent cohorts. Combining MREPT and IVIM-based ISF-related metrics may provide a non-invasive imaging framework to probe these complex microenvironmental alterations in cognitive impairment.

Advancements in semiconductor technology have significantly improved the performance of DRAM and NAND flash, establishing them as high-speed main memory and high-capacity storage, respectively. However, the persistent performance gap between these two memory types remains a critical bottleneck in modern computing systems. To address this challenge, we propose a hybrid memory architecture, termed NAD, which tightly integrates DRAM and NAND flash to enable direct and parallel data transfer. By eliminating intermediate components such as I/O buffers and data buses typically used for inter-memory communication, the proposed NAD architecture significantly reduces data transfer latency. To validate its functionality, NAD memory was fabricated using a TSMC 180 nm CMOS logic process. Experimental results confirm reliable data transfer between DRAM and NAND flash, demonstrating the feasibility of NAD as a promising solution for overcoming memory bottlenecks in next-generation computing systems.

Background: The diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) index has been proposed as an imaging marker of impaired perivascular water transport across the Alzheimer's disease (AD) continuum. Whether a conductivity-based ALPS derived from conductivity tensor imaging (CTI) provides a distinct physiological perspective remains to be explored. This work introduces the CTI-ALPS index. The purpose of this study was (1) to introduce the CTI-ALPS index and (2) to evaluate both the CTI-ALPS and DTI-ALPS indices in cognitively normal (CN) older adults, amnestic mild cognitive impairment (aMCI), and mild-to-moderate AD. Methods: ) and magnetic resonance electrical property tomography (MREPT)to calculate DTI-ALPS and CTI-ALPS, respectively. Diagnostic performance and correlation with cognitive function were evaluated. Results: CTI-ALPS showed lower in AD but did not differ significantly across groups and demonstrated weaker associations with Mini-Mental State Examination (MMSE) scores. In age-adjusted ROC analyses for differentiating AD from CN, CTI-ALPS achieved modest discrimination, whereas DTI-ALPS provided slightly higher diagnostic performance. Conclusion: CTI-ALPS demonstrated a non-significant trend towards a reduction in AD and modest diagnostic utility, with weaker clinical associations than DTI-ALPS in this cohort. As an initial exploratory study, conductivity-based ALPS may serve as a distinct physical contrast reflecting ionic physiological perivascular marker, alongside diffusion-based measures, and warrants further validation with larger, age-matched datasets and reproducibility-focused designs.

Abstract Ocean Alkalinity Enhancement (OAE) in coastal and open‐ocean environments has been proposed as a scalable method for atmospheric CO 2 removal. However, the effects of OAE on marine calcifiers, such as foraminifera, remain under‐constrained. Determining the response of marine calcifiers to OAE is critical because alkalinity uptake during calcification reduces the intended CO 2 removal from the atmosphere. Here we utilize X‐Ray Micro‐Computed Tomography imaging to quantify the calcification response of Globigerina bulloide s grown in culture under two OAE scenarios. These scenarios most closely simulate equilibration with atmospheric CO 2 , corresponding to modest increases in the saturation state, and using NaHCO 3 as an alkalinity source. We assess changes in calcification using two metrics: shell density as indicated by mean CT number, and calcite mass added relative to the amount of shell elongation. An alkalinity increase of 350 μmol/kg significantly increased both metrics, indicating enhanced calcification of G. bulloides as a result of alkalinity addition. We extrapolate our culture results from G. bulloides to estimate increases in CaCO 3 flux driven by planktic foraminifera in response to large‐scale OAE deployment, and discuss factors that will impact the global, multi‐species nature of the planktic foraminiferal calcification response in the open ocean. While our preliminary results from G. bulloides point to a minor mitigating impact of foraminifera calcification on OAE efficacy, we argue that pelagic calcification should be considered when estimating OAE efficacy and future potential for deployment in the open ocean as a method for atmospheric CO 2 removal.