Attojoule Hexagonal Boron Nitride-Based Memristor for High-Performance Neuromorphic Computing.

In next-generation neuromorphic computing applications, the primary challenge lies in achieving energy-efficient and reliable memristors while minimizing their energy consumption to a level comparable to that of biological synapses. In this work, hexagonal boron nitride (h-BN)-based metal-insulator-semiconductor (MIS) memristors operating is presented at the attojoule-level tailored for high-performance artificial neural networks. The memristors benefit from a wafer-scale uniform h-BN resistive switching medium grown directly on a highly doped Si wafer using metal-organic chemical vapor deposition (MOCVD), resulting in outstanding reliability and low variability.

Active Sites of Mixed-Metal Core-Shell Oxygen Evolution Reaction Catalysts: FeO Sites on Ni Cores or NiN Sites in C Shells?

Water electrolysis for clean hydrogen production requires high-activity, high-stability, and low-cost catalysts for its particularly sluggish half-reaction, the oxygen evolution reaction (OER). Currently, the most promising of such catalysts working in alkaline conditions is a core-shell nanostructure, NiFe@NC, whose Fe-doped Ni (NiFe) nanoparticles are encapsulated and interconnected by N-doped graphitic carbon (NC) layers, but the exact OER mechanism of these catalysts is still unclear, and even the location of the OER active site, either on the core side or on the shell side, is still debated. Therefore, we herein derive a plausible active-site model for each side based on various experimental evidence and density functional theory calculations and then build OER free-energy diagrams on both sides to determine the active-site location.

Superficial Radial Neuropathy due to Anatomic Variation: A Case Report.

Superficial radial neuropathy is a purely sensory neuropathy, usually caused by nerve entrapment in the distal forearm. We report a case of superficial radial neuropathy caused by the anomalous course of the superficial radial nerve, which was found to be spirally encircling the brachioradialis tendon in the distal forearm. To the best of our knowledge, this is the first report of an anatomical variant of the superficial radial nerve that causes neuropathy.

Intradural Extramedullary Ependymoma with Hemorrhage: A Case Report.

In adults, spinal ependymomas are usually found in intramedullary locations. However, intradural extramedullary spinal ependymomas are rare. Additionally, spinal ependymomas usually show iso to hypointensity on T1-weighted images without hemorrhage.

Thermodynamically Driven Tilt Grain Boundaries of Monolayer Crystals Using Catalytic Liquid Alloys.

We report a method to precisely control the atomic defects at grain boundaries (GBs) of monolayer MoS by vapor-liquid-solid (VLS) growth using sodium molybdate liquid alloys, which serve as growth catalysts to guide the formations of the thermodynamically most stable GB structure. The Mo-rich chemical environment of the alloys results in Mo-polar 5|7 defects with a yield exceeding 95%. The photoluminescence (PL) intensity of VLS-grown polycrystalline MoS films markedly exceeds that of the films, exhibiting abundant S 5|7 defects, which are kinetically driven by vapor-solid-solid growths.

Ionic Liquids for Intrinsically Stretchable Conductive Polymers.

Inspired by the classic hard-soft acid-base theory and intrigued by a theoretical prediction of spontaneous ion exchange between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and hard-cation-soft-anion ionic liquid (IL), we treat PEDOT:PSS with a new IL composed of a (., extremely hard) cation (3-methylimidazolium, -MIM) and an extremely soft anion (tetracyanoborate, TCB). In fact, this IL (-MIM:TCB) accomplishes the same levels of ion-exchange-mediated PEDOT-PSS separation, PEDOT-rich nanofibril formation, and electrical conductivity enhancement (∼2500 S/cm) as its counterpart (EMIM:TCB with 1-ethyl-3-methylimidazolium), the best IL used for this purpose so far.

A Molecular-Switch-Embedded Organic Photodiode for Capturing Images against Strong Backlight.

When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light-intensity-dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes the threshold intensity. The photoactive layer is doped with a strategically designed and synthesized molecular switch, 1,2-bis-(2-methyl-5-(4-cyanobiphenyl)-3-thienyl)tetrafluorobenzene (DAB).

Hard-Cation-Soft-Anion Ionic Liquids for PEDOT:PSS Treatment.

A promising conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) experiences significant conductivity enhancement when treated with proper ionic liquids (ILs). Based on the hard-soft-acid-base principle, we propose a combination of a hydrophilic hard cation A (instead of the commonly used 1-ethyl-3-methyl imidazolium, EMIM) and a hydrophobic soft anion X (such as tetracyanoborate, TCB) as the best ILs for this purpose. Such ILs would decouple hydrophilic-but-insulating PSS from conducting-but-hydrophobic PEDOT most efficiently by strong interactions with hydrophilic A and hydrophobic X, respectively.

Effect of Bulky Atom Substitution on Backbone Coplanarity and Electrical Properties of Cyclopentadithiophene-Based Semiconducting Polymers.

The effect of atomic substitution on the optoelectronic properties of a coplanar donor-acceptor (D-A) semiconducting polymer (SPs), prepared using cyclopentadithiophene (CDT) and 2,1,3-benzothiadiazole (BT) moieties, is investigated. By substituting a carbon atom in the BT unit with CF or C-Cl, two random D-A SPs are prepared, and their optoelectronic properties are thoroughly investigated. Density functional theory calculations demonstrate that the fluorinated polymer has a slightly smaller dihedral angle (ϴ = 0.

Avulsion injuries: an update on radiologic findings.

Avulsion injuries result from the application of a tensile force to a musculoskeletal unit or ligament. Although injuries tend to occur more commonly in skeletally immature populations due to the weakness of their apophysis, adults may also be subject to avulsion fractures, particularly those with osteoporotic bones. The most common sites of avulsion injuries in adolescents and children are apophyses of the pelvis and knee.

Molecular Dynamics of PEDOT:PSS Treated with Ionic Liquids. Origin of Anion Dependence Leading to Cation Design Principles.

Conductivity enhancement of PEDOT:PSS via the morphological change of PEDOT-rich domains has been achieved by introducing a 1-ethyl-3-methylimidazolium (EMIM)-based ionic liquid (IL) into its aqueous solution, and the degree of such change varies drastically with the anion coupled to the EMIM cation constituting the IL. We carry out a series of molecular dynamics simulations on various simple model systems for the extremely complex mixtures of PEDOT:PSS and EMIM:X IL in water, varying the anion X, the IL concentration, the oligomer model of PEDOT:PSS, and the size of the model systems. The common characteristic found in all simulations is that although planar hydrophobic anions X are the most efficient for ion exchange between PEDOT:PSS and EMIM:X, they tend to bring together planar EMIM cations to PEDOT-rich domains, disrupting PEDOT π-stacks with PEDOT-X-EMIM intercalating layers.

Pristine Graphene Insertion at the Metal/Semiconductor Interface to Minimize Metal-Induced Gap States.

Metal (M) contact with a semiconductor (S) introduces metal-induced gap states (MIGS), which makes it difficult to study the intrinsic electrical properties of S. A bilayer of metal with graphene (Gr), ., a M/Gr bilayer, may form a contact with S to minimize MIGS.

Ionic Liquid for PEDOT:PSS Treatment. Ion Binding Free Energy in Water Revealing the Importance of Anion Hydrophobicity.

Water solubility of PEDOT:PSS conducting polymer is achieved by PSS at the expense of disturbing the crystallinity and electron mobility of PEDOT. Recently, PEDOT crystallinity and electron mobility have been improved by treating the PEDOT:PSS aqueous solution with 1-ethyl-3-methylimidazolium- (EMIM-) based ionic liquids (IL) EMIM:X. The amount of such improvement varies drastically with the anion X coupled to EMIM cation in the IL.

Molecular Engineering of a Donor-Acceptor Polymer To Realize Single Band Absorption toward a Red-Selective Thin-Film Organic Photodiode.

Herein, we explore the strategy of realizing a red-selective thin-film organic photodiode (OPD) by synthesizing a new copolymer with a highly selective red-absorption feature. PCZ-Th-DPP, with phenanthrocarbazole (PCZ) and diketopyrrolopyrrole (DPP) as donor and acceptor units, respectively, was strategically designed/synthesized based on a time-dependent density functional theory calculation, which predicted the significant suppression of the band II absorption of PCZ-Th-DPP due to the extremely efficient intramolecular charge transfer. We demonstrate that the synthesized PCZ-Th-DPP exhibits not only a high absorption coefficient within the red-selective band I region, as theoretically predicted, but also a preferential face-on intermolecular structure in the thin-film state, which is beneficial for vertical charge extraction as an outcome of a glancing incidence X-ray diffraction study.

Genome wide expression analysis of the effect of Pinelliae Rhizoma extract on psychological stress.

Pinelliae Rhizoma has been used traditionally as an antidepressant in Oriental medicine. In this study, the effect of Pinelliae Rhizoma extract (PRe) on psychological stress was investigated in mice. The results of an elevated plus-maze experiment revealed that application of psychological stress to mice led to the development of an abnormal behavioral pattern.