Despite growing interest in doping two-dimensional (2D) transition metal dichalcogenides (TMDs) for future layered semiconductor devices, controllability is currently limited to only heavy doping ...(degenerate regime). This causes 2D materials to act as metallic layers, and an ion implantation technique with precise doping controllability is not available for these materials (e.g., MoS2, MoSe2, WS2, WSe2, graphene). Since adjustment of the electrical and optical properties of 2D materials is possible within a light (nondegenerate) doping regime, a wide-range doping capability including nondegenerate and degenerate regimes is a critical aspect of the design and fabrication of 2D TMD-based electronic and optoelectronic devices. Here, we demonstrate a wide-range controllable n-doping method on a 2D TMD material (exfoliated trilayer and bulk MoS2) with the assistance of a phosphorus silicate glass (PSG) insulating layer, which has the broadest doping range among the results reported to date (between 3.6 × 1010 and 8.3 × 1012 cm ‑2) and is also applicable to other 2D semiconductors. This is achieved through (1) a three-step process consisting of, first, dopant out-diffusion between 700 and 900 °C, second, thermal activation at 500 °C, and, third, optical activation above 5 μW steps and (2) weight percentage adjustment of P atoms in PSG (2 and 5 wt %). We anticipate our widely controllable n-doping method to be a starting point for the successful integration of future layered semiconductor devices.
Functional gene transfer from organelles to the nucleus, known as intracellular gene transfer (IGT), is an ongoing process in flowering plants. The complete plastid genomes (plastomes) of two Ulleung ...island endemic violets,
Viola ulleungdoensis
and
V. woosanensis
, were characterized, revealing a lack of the plastid-encoded
infA
,
rpl32
, and
rps16
genes. In addition, functional replacement of the three plastid-encoded genes in the nucleus was confirmed within the genus
Viola
and the order Malpighiales. Three strategies for the acquisition of a novel transit peptide for successful IGT were identified in the genus
Viola
. Nuclear
INFA
acquired a novel transit peptide with very low identity between these proteins, whereas the nuclear
RPL32
gene acquired an existing transit peptide
via
fusion with the nuclear-encoded plastid-targeted
SOD
gene (Cu-Zn superoxide dismutase superfamily) as one exon, and translated both proteins in the cytosol using alternative mRNA splicing. Nuclear
RPS16
contains an internal transit peptide without an N-terminal extension. Gene loss or pseudogenization of the plastid-borne
rpl32
and
rps16
loci was inferred to occur in the common ancestor of the genus
Viola
based on an infrageneric phylogenetic framework in Korea. Although
infA
was lost in the common ancestor of the order Malpighiales, the
rpl32
and
rps16
genes were lost multiple times independently within the order. Our current study sheds additional light on plastid genome composition and IGT mechanisms in the violet genus and in the order Malpighiales.
Abstract
In this review, p‐type doping technologies for organic/polymeric semiconductors in hole transporting layer (HTL) for perovskite solar cells (PSCs) are examined. Initially, we investigate the ...conventional dopant systems used for HTL in terms of dopants and additives, as well as their doping principles and limitations. Second, we recapitulate the current research strategies for overcoming the limitations of conventional dopant systems: (i) dopants/additives with large cations, (ii) hydrophobic dopants/additives, (iii) locking‐capable dopants/additives, (iv) rinsing or ion exchange methods, and (v) other methods. Afterwards, we provide a comprehensive analysis of alternative dopants based on ionic liquids, Lewis acids, strong acceptors, and others. In addition, the review emphasizes current achievements based on multiple research approaches to diverse hole transporting materials, surface/interfacial treatment, and architectural modification of HTL, and provides a perspective on developments of desirable HTL system for efficient and stable PSCs.
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Conventional DNN inference accelerators are designed with a few (up to four) large systolic arrays. As such a scale-up architecture often suffers from low utilization, a scale-out architecture, in ...which a single accelerator has tens of pods and each pod has a small systolic array, has been proposed. While the scale-out architecture is promising, it still incurs increasing off-chip memory access as the pods are supposed to access the duplicate tiles of tensors. Prior work has proposed a shared buffer structure to address the problem, but those architectures suffer from performance degradation due to shared buffer access latency. We make an observation that all the pods access the same rows of input and weights within a short time window. With the observation, we propose a new inference accelerator architecture, called Vectored Systolic Arrays (SAVector). SAVector consists of a new two-level on-chip buffer architecture and a tensor tile scheduling technique. In the new buffer architecture, global buffers are shared by all the pods and they keep the rows shared by the pods. And each pod has a tiny dedicated buffer. SAVector monitors the memory access behavior and timely determines to prefetch the data and flush it. In our evaluation, SAVector exhibits a very similar off-chip memory access count to the scale-up architecture and achieves 52% energy-delay-product (EDP) reduction. Also, SAVector achieves 27% EDP reduction over prior work by mitigating performance degradation from global buffer access latency.
We have developed a model to predict the chemical reactivity of carbon nanotubes (CNTs) quantitatively from their initial structures. The parameters, universal for each reaction, of the model can be ...obtained from a graphene sheet analysis. The chemical reactivity of hydrogenation, hydroxylation, and fluorination were predicted within 0.1−0.3 eV errors, compared with first principle simulation results. The model also predicted the enhanced chemical reactivity of mechanically bent CNTs. The predictions can be applied to the controlled functionalization of CNTs.
Major earthquakes in continental regions may cause significant damage. Preexisting fault system across megacity receives high attention for possible seismic damages. Earthquake occurrence mechanism ...is important to assess the geohazard potentials. Continental‐scale Quaternary fault system is developed across the Seoul metropolitan area where the population is the largest in the Korean Peninsula. Historical seismic‐damage records suggest potential seismic hazards in the Seoul metropolitan area. We investigate the fault motions and spatial distribution of earthquakes in the Seoul metropolitan area using a matched‐filter technique that is based on stacked waveform crosscorrelation functions among densely‐deployed seismic stations. The analysis detects 1103 earthquakes that include 360 events with magnitudes (ML) of −0.6 to 2.0 around the Chugaryeong fault and 34 events with magnitudes of −0.5 to 2.7 around Wangsukcheon, Pocheon, and Yeseonggang faults. The seismicity suggests a set of near‐vertical subparallel (or orthogonal) faults that develop from the major faults. A major fault system behaves as a backbone structure that makes branch faults develop, producing seismicity including major earthquakes. The backbone structure may control the fault development that conforms to the ambient stress field. The backbone faults may play a role to increase geohazard potentials.
Plain Language Summary
The Seoul metropolitan area is the most populated region in the Korean Peninsula. Historical seismic damage records and major Quaternary faults suggest high seismic hazard potentials in the region. The identification of earthquake‐spawning faults is crucial for seismic hazard mitigation. We illuminate the earthquake‐spawning faults from micro to small earthquakes in the Seoul metropolitan. We perform a matched‐filter analysis to find earthquakes in adjacent locations of reported events. Recently‐deployed temporary dense seismic stations allow us to detect microearthquakes in high ambient‐noise environments of the megacity. We detect 1103 earthquakes that include 360 events with magnitudes (ML) of −0.6 to 2.0 around the Chugaryeong fault and 34 events with magnitudes (ML) of −0.5 to 2.7 around Wangsukcheon, Pocheon, and Yeseonggang faults. The earthquake distribution suggests the presence of active near‐vertical subparallel or conjugate faults along the major Quaternary faults that may behave as backbones of earthquake‐spawning faults.
Key Points
Micro to small earthquakes occur around Quaternary faults in the Seoul metropolitan area
Subvertical strike‐slip faults develop along the Quaternary faults, responding to the ambient stress field
Clustered earthquakes occur along conjugate or subparallel faults
Additive interface materials for improved ionic polymer metal composite (IPMC) actuator performance are being investigated. In this study, three-dimensional carbon nanostructure/copper nanowire (3DC ...Cu-NW) with a novel structure was synthesized via low-pressure chemical vapor deposition. An IPMC actuator with a 3DC Cu-NW interface layer was fabricated, which exhibited improved actuation performance, long-term stability, and electrochemical properties. The proposed 3DC consists of carbon nanotubes (CNTs) and graphene, grown using an Fe catalyst and CH
gas, respectively. We optimized the growth conditions (Fe catalyst: 12.5 mg/L, CH
: 20 sccm) to achieve a 3DC with an appropriate thickness and a large specific surface area. The 3DC Cu-NW benefited from a Cu oxidation prevention property and a large specific surface area. The electrochemical properties and actuation performance of the IPMC actuator improved with an increased 3DC Cu-NW concentration. An IPMC actuator with a 0.6 wt% 3DC Cu-NW interface layer exhibited 1.3- and 5.6-fold electrochemical property and actuation performance improvement, respectively, over an IPMC actuator with no 3DC Cu-NW interface layer. These results show that the proposed 3DC Cu-NW has potential as an IPMC actuator interface material, and that 3DC Cu-NW synthesis and application technology can be applied to future research on sensor, actuator, and flexible devices.
Along with the advancement in neural engineering techniques, unprecedented progress in the development of neural interfaces has been made over the past few decades. However, despite these ...achievements, there is still room for further improvements especially toward the possibility of monitoring and modulating neural activities with high resolution and specificity in our daily lives. In an effort of taking a step toward the next-generation neural interfaces, we want to highlight the recent progress in neural technologies. We will cover a wide scope of such developments ranging from novel platforms for highly specific recording and modulation to system integration for practical applications of novel interfaces.
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Neuroscience; Techniques in neuroscience; Biotechnology; Bioelectronics
Ischemic stroke-induced neuronal cell death leads to the permanent impairment of brain function. The Fas-mediating extrinsic apoptosis pathway and the cytochrome c-mediating intrinsic apoptosis ...pathway are two major molecular mechanisms contributing to neuronal injury in ischemic stroke. In this study, we employed a Fas-blocking peptide (FBP) coupled with a positively charged nona-arginine peptide (9R) to form a complex with negatively charged siRNA targeting Bax (FBP9R/siBax). This complex is specifically designed to deliver siRNA to Fas-expressing ischemic brain cells. This complex enables the targeted inhibition of Fas-mediating extrinsic apoptosis pathways and cytochrome c-mediating intrinsic apoptosis pathways. Specifically, the FBP targets the Fas/Fas ligand signaling, while siBax targets Bax involved in mitochondria disruption in the intrinsic pathway. The FBP9R carrier system enables the delivery of functional siRNA to hypoxic cells expressing the Fas receptor on their surface-a finding validated through qPCR and confocal microscopy analyses. Through intranasal (IN) administration of FBP9R/siCy5 to middle cerebral artery occlusion (MCAO) ischemic rat models, brain imaging revealed the complex specifically localized to the Fas-expressing infarcted region but did not localize in the non-infarcted region of the brain. A single IN administration of FBP9R/siBax demonstrated a significant reduction in neuronal cell death by effectively inhibiting Fas signaling and preventing the release of cytochrome c. The targeted delivery of FBP9R/siBax represents a promising alternative strategy for the treatment of brain ischemia.
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