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Enhancement of the cyclic stability of a Li-excess layered oxide through a simple electrode treatment for LiF-coating
No full textLithium-rich layered cathodes (LLCs) are considered to be promising next-generation materials for lithium-ion batteries (LIBs) due to their high specific capacity and energy density. However, their poor cyclability poses a significant challenge for commercial applications. In this study, we introduce a straightforward one-step electrode heat-treatment method involving a lithium fluoride (LiF) coating on conventional LLCs, without the need for additional coating precursors, to enhance the cyclability. During the heat-treatment, lithium residues (LiOH and Li2CO3) and the PVDF used as a binder react to form an amorphous LiF coating layer (LiF-LLC). Although LiFLLC initially exhibited a lower capacity compared to pristine LLC (220.2 vs. 246.6 mAh g-1) due to its higher overpotential, it demonstrated superior performance after 100 cycles at 0.2 C. LiF-LLC maintained a discharge capacity of 219.4 mAh g-1 with 95.1 % retention, while pristine LLC showed an outcome of only 164.8 mAh g-1 with 83.4 % retention. A comprehensive analysis revealed that the LiF coating layer effectively passivated the cathode interface, preventing transition metal dissolution and a phase transformation caused by a HF attack. Additionally, LiF-LLC exhibited higher lithium-ion diffusivity, lower interfacial impedance, and enhanced Mnand O-ion redox activities. These findings demonstrate that the simple electrode heat-treatment significantly improves the cyclic stability of LLCs.
Facile membrane upscaling via in-situ synthesis of PVA hydrogel for harsh solvent separation: From transport study to industrial application
No full textIn this study, a facile upscaled membrane module was developed using an in-situ hydrogel synthesis technique for the selective removal of water from harsh organic solvent mixtures by pervaporation. Polyvinyl alcohol (PVA) was chosen as the hydrophilic membrane material due to its ease of chemical modification and high processible film-forming stability. A porous alpha-alumina hollow fiber was used as a support, and an in-situ hydrogel reaction with glutaraldehyde was employed to form a uniform selective layer without the penetration issues commonly faced during conventional membrane fabrication. It was found that the synthesized hydrogel (s-HPGA) exhibited improved water permeation performance resulting from the mechanically expanded free volume within the membrane matrix and uncommon diffusive properties verified by diffusivity modeling. The effectiveness of the fabricated s-HPGA membrane modules was demonstrated through a cyclic pervaporation test involving an epoxy manufacturing by-product mixture. The results showed that the module achieved stable performance and efficient water separation over 200 h of operation with a recovery rate of over 98%. In addition, the field application test demonstrated that the s-HPGA membrane module is well-suited for industrial applications requiring solvent enrichment and efficient dehydration.
In Situ Observations of CO2 Activation on the PdIn(111) Alloy Surface at Ambient Pressures
No full textThe CO2 activation process has been investigated on the palladium-indium (PdIn) (111) alloy surface using ambient pressure scanning tunneling microscopy (AP-STM) and synchrotron-based X-ray photoelectron spectroscopy (AP-XPS). Pd and In atoms diffuse onto the topmost layer after annealing at 840 K, which adopts intermetallic PdIn alloy geometries in an ultrahigh vacuum. AP-STM reveals that interfacial Pd-InO x nanostructures are created on the alloy surface by dissociative CO2 adsorption under CO2(g) environments even at 300 K. Synchrotron-based AP-XPS measurements support the idea that the observed CO2 activation induces InO x segregation onto the PdIn(111) surface by dissociated atomic oxygen from CO2. After all, CO2 gas molecules simultaneously adsorb onto the oxygen-terminated sites of the Pd-InO x nanoclusters to produce carbonate species. Our in situ observations indicate that the restructuring metastable PdIn(111) alloy surface may provide active sites for efficient CO2 activation, contributing to the rational catalyst design toward sustainable CO2 utilizations.
Triboelectric nanogenerator for modulating neuronal outgrowth and neuroplasticity through controlled stimulation
No full textElectrical stimulation effectively accelerates rehabilitation but is limited by the reliance on external power sources or frequent battery replacements, reducing its practicality for long-term use. To address this limitation, triboelectric nanogenerators (TENGs) offer a self-powered alternative, converting human kinetic energy into electrical energy. Although promising in both in vitro and in vivo studies, TENG-based stimulation is constrained by insufficient current output, falling short of the milliampere range needed for effective stimulation. In this study, we developed a TENG system with periodic switching to overcome these limitations, achieving higher current output and reduced internal impedance. The TENG device was integrated with an agar salt bridge setup to deliver controlled electric field (EF) stimulation to neurons isolated from rat pup brains. Subthreshold EF stimulation and suprathreshold EF stimulation were systematically compared for their effects on neuronal outgrowth. Immunofluorescence analysis revealed that subthreshold stimulation primarily induced neurite sprouting, characterized by increased attachment points and initial elongation, whereas suprathreshold stimulation significantly enhanced neurite branching, morphological complexity, and synaptogenesis. These morphological trends were further supported by qPCR analysis, which demonstrated a dose-dependent upregulation of neuroplasticity-related genes, including those associated with neurite outgrowth. Together, these findings highlight the efficacy of TENG-based EF stimulation in promoting neuroplasticity and suggest its potential as a scalable, self-powered tool for facilitating neuronal recovery and rehabilitation following injuries.
ShieldCXL: A Practical Obliviousness Support with Sealed CXL Memory
No full textThe CXL (Compute Express Link) technology is an emerging memory interface with high-level commands. Recent studies applied the CXL memory expanding technique to mitigate the capacity limitation of the conventional DDRx memory. Unlike the prior studies to use the CXL memory as the capacity expander, this study proposes to use the CXL-based memory as a secure main memory device, while removing the conventional memory. In the conventional DDRx memory, to provide confidentiality, integrity, replay protection, and obliviousness, costly mechanisms such as counter-based integrity trees and location shuffling by ORAM (Oblivious RAM) are used. Such mechanisms incur significant performance degradation in the current DDR-based memory systems, and their costs increase as the capacity of the memory increases. To mitigate the performance degradation, the prior work proposed an obfuscated channel for a secure memory module enclosing its controller in the package. Based on the approach, we propose a secure CXL-only memory architecture called ShieldCXL. It uses the channel encryption and integrity protection mechanism of the CXL interface to provide a practical ORAM while supporting confidentiality, integrity, and replay protection from physical attacks and rowhammers. To protect the PCIe-connected memory expanding board, this study proposes to use the standard physical sealing technique to detect physical intrusion. To mitigate the increased latency with the sealed CXL memory module, the study further optimizes performance by adopting an in-package DRAM cache. In addition, this study investigates destination obfuscation when a CXL switch is used to route among multiple hosts and memory devices. The evaluation shows that ShieldCXL provides 9.16x performance improvements over the prior ORAM technique.
Ultrafast, cytocompatible mineralization of calcium phosphate in the formation of stratified nanoshells of artificial spores
No full textSpatially controlled confinement of catalytic enzymes within nanoshells holds substantial potential for applications in bioreactors, synthetic cells, and artificial spores. The utilization of amorphous calcium phosphate (CaP) precursors enables the extremely rapid (<5 seconds) construction of thick (similar to 400 nm) CaP nanoshells, stratified with distinct enzymes, on various tannic acid-primed substrates. Saccharomyces cerevisiae cells are nanoencapsulated with enzyme-embedded, multilayered CaP nanoshells in a cytocompatible manner, providing an advanced chemical tool for interfacing living cells with functional entities in a spatially controlled configuration.
DEEP LEARNING USING EMBEDDING VECTORS OF HETEROGENEOUS DATA-SETS IN MULTI-DISTRIBUTED DATABASE ENVIRONMENTS
No full text일 실시예에 따르면, 다중 분산 데이터베이스 환경에서 딥 러닝 학습 장치가 수행하는 딥 러닝 학습 방법은, 다중 분산 데이터베이스의 이종 데이터세트를 시계열 기준으로 병합하여 모델 학습을 위한 입력 스트림을 생성하는 단계와, 상기 입력 스트림에 대한 임베딩 벡터를 생성하는 단계와, 상기 임베딩 벡터를 딥 러닝 모델의 학습과 기학습된 딥 러닝 모델을 통한 추론 중 적어도 하나에 적응적으로 반영하는 단계를 포함한다
A sensor for detecting a degree of hydrogenation of an aromatic solute using a phase change in solution and a method for measuring a degree of hydrogenation using the same
No full text본 발명은 혼합 용액에서 상전이 현상을 이용한 방향족 용질의 수소화도 검출 센서 및 이를 이용하여 방향족 용질의 수소화도를 측정하는 방법에 관한 것이다. 본 발명에 따른 혼합 용액에 포함된 방향족 용질의 수소화도 검출 센서 및 이를 이용한 수소화도 측정 방법에 의하면, 온도 감응성 고분자의 상전이 현상 및 흐림점의 측정을 통하여 간단한 방법으로 혼합 용액에 포함된 방향족 용질의 수소화도를 측정할 수 있는 장점이 있다
MOTT MEMRISTOR BASED TRUE RANDOM NUBMER GENERATOR AND TRUE RANDOM NUBMER GENERATING METHOD
No full text본 발명에 따른 진성난수생성기는 구동전압에 기초하여 오실레이팅 출력신호를 생성하는 랜덤소스부, 발열전압에 기초하여 생성된 열을 상기 랜덤소스부에 전달하는 히터(heater), 및 상기 랜덤소스부에서 생성된 출력신호를 인가받아 이진화된 난수를 생성하는 바이너라이저(binarizer)를 포함한다. 본 발명에 따른 모트 멤리스터 기반 진성난수생성기 및 진성난수생성방법에 의하면, 히터를 이용하여 랜덤소스부에 열을 공급함으로써 진성난수의 생성속도를 가속화할 수 있게 된다. 또한, 소자의 수가 매우 적은 심플한 회로의 히터만을 채용하고, 랜덤소스부와 바이너라이저 사이에 개재하는 소자가 없기 때문에 높은 직접화를 도모할 수 있다. 또한, 히터를 발열시키기 위한 에너지만을 필요로 하기 때문에 낮은 소비효율로도 빠르게 난수를 생성할 수 있게 된다