In recent years, organic resistive memory devices in which active organic materials possess at least two stable resistance states have been extensively investigated for their promising memory ...potential. From the perspective of device fabrication, their advantages include simple device structures, low fabrication costs, and printability. Furthermore, their exceptional electrical performances such as a nondestructive reading process, nonvolatility, a high ON/OFF ratio, and a fast switching speed meet the requirements for viable memory technologies. Full understanding of the underlying physics behind the interesting phenomena is still challenging. However, many studies have provided useful insights into scientific and technical issues surrounding organic resistive memory. This Feature Article begins with a summary on general characteristics of the materials, device structures, and switching mechanisms used in organic resistive devices. Strategies for performance enhancement, integration, and advanced architectures in these devices are also presented, which may open a way toward practically applicable organic memory devices.
Recently, organic resistive memory devices, which have many advantages including simple device structures, low fabrication costs, and printability, have been extensively investigated. The focus of this Feature Article is on essential strategies for memory performance enhancement, high‐density integration, and advanced architectural concepts necessary for future memory applications.
Lead‐(Pb‐) halide perovskite nanocrystals (NCs) are interesting nanomaterials due to their excellent optical properties, such as narrow‐band emission, high photoluminescence (PL) efficiency, and wide ...color gamut. However, these NCs have several critical problems, such as the high toxicity of Pb, its tendency to accumulate in the human body, and phase instability. Although Pb‐free metal (Bi, Sn, etc.) halide perovskite NCs have recently been reported as possible alternatives, they exhibit poor optical and electrical properties as well as abundant intrinsic defect sites. For the first time, the synthesis and optical characterization of cesium ytterbium triiodide (CsYbI3) cubic perovskite NCs with highly uniform size distribution and high crystallinity using a simple hot‐injection method are reported. Strong excitation‐independent emission and high quantum yields for the prepared NCs are verified using photoluminescence measurements. Furthermore, these CsYbI3 NCs exhibit potential for use in organic–inorganic hybrid photodetectors as a photoactive layer. The as‐prepared samples exhibit clear on–off switching behavior as well as high photoresponsivity (2.4 × 103 A W−1) and external quantum efficiency (EQE, 5.8 × 105%) due to effective exciton dissociation and charge transport. These results suggest that CsYbI3 NCs offer tremendous opportunities in electronic and optoelectronic applications, such as chemical sensors, light emitting diodes (LEDs), and energy conversion and storage devices.
The rare‐earth element ytterbium (Yb) is substituted into the B site of a cubic ABX3 perovskite lattice in place of lead. The resulting CsYbI3 nanocrystals exhibit strong excitonic emission with high quantum yield and the potential for use in hybrid photodetectors as a photoactive layer. Such lead‐free CsYbI3 nanocrystals offer tremendous opportunities in optical and optoelectronic applications.
The recent increase in anthropogenic emissions of reactive nitrogen from northeastern Asia and the subsequent enhanced deposition over the extensive regions of the North Pacific Ocean (NPO) have led ...to a detectable increase in the nitrate (N) concentration of the upper ocean. The rate of increase of excess N relative to phosphate (P) was found to be highest (∼0.24 micromoles per kilogram per year) in the vicinity of the Asian source continent, with rates decreasing eastward across the NPO, consistent with the magnitude and distribution of atmospheric nitrogen deposition. This anthropogenically driven increase in the N content of the upper NPO may enhance primary production in this N-limited region, potentially leading to a long-term change of the NPO from being N-limited to P-limited.
The impacts of anthropogenic nitrogen (N) deposition on the marine N cycle are only now being revealed, but the magnitudes of those impacts are largely unknown in time and space. The South China Sea ...(SCS) is particularly subject to high anthropogenic N deposition, because the adjacent countries are highly populated and have rapidly growing economies. Analysis of data sets for atmospheric N deposition, satellite chlorophyll‐a (Chl‐a), and air mass back trajectories reveals that the transport of N originating from the populated east coasts of China and Indonesia, and its deposition to the ocean, has been responsible for the enhancements of Chl‐a in the SCS. We found that atmospheric N deposition contributed approximately 20% of the annual biological new production in the SCS. The airborne contribution of N to new production in the SCS is expected to grow considerably in the coming decades.
Key Points
N deposition contributed ~20% of the new production in the South China Sea
Air masses from highly populated regions increased the Chl‐a concentration
Colloidal‐quantum‐dot (CQD) photovoltaic devices are promising candidates for low‐cost power sources owing to their low‐temperature solution processability and bandgap tunability. A power conversion ...efficiency (PCE) of >10% is achieved for these devices; however, there are several remaining obstacles to their commercialization, including their high energy loss due to surface trap states and the complexity of the multiple‐step CQD‐layer‐deposition process. Herein, high‐efficiency photovoltaic devices prepared with CQD‐ink using a phase‐transfer‐exchange (PTE) method are reported. Using CQD‐ink, the fabrication of active layers by single‐step coating and the suppression of surface trap states are achieved simultaneously. The CQD‐ink photovoltaic devices achieve much higher PCEs (10.15% with a certified PCE of 9.61%) than the control devices (7.85%) owing to improved charge drift and diffusion. Notably, the CQD‐ink devices show much lower energy loss than other reported high‐efficiency CQD devices. This result reveals that the PTE method is an effective strategy for controlling trap states in CQDs.
A colloidal quantum dot (CQD)‐ink is developed by phase‐transfer exchange, enabling the fabrication of active layers by single‐step coating to achieve a thick film. The CQD‐ink exhibits low surface traps due to improvement of surface passivation. Thus, incorporating the CQD‐ink into devices shows high efficiency and low voltage loss.
Scope
Intestinal dysbiosis has been reported to play an important role in the pathogenesis of various diseases, including chronic kidney disease (CKD). Here, to evaluate whether probiotic supplements ...can have protective effects against kidney injury in an animal model of CKD is aimed.
Methods and results
An animal model of CKD is established by feeding C57BL/6 mice a diet containing 0.2% adenine. These model mice are administered Lactobacillus acidophilus KBL409 daily for 4 weeks. Features of adenine‐induce CKD (Ade‐CKD) mice, such as prominent kidney fibrosis and higher levels of serum creatinine and albuminuria are improved by administration of KBL409. Ade‐CKD mice also exhibit a disrupted intestinal barrier and elevate levels of TNF‐α, IL‐6, and 8‐hydroxy‐2′‐deoxyguanosine. These changes are attenuated by KBL409. Administration of KBL409 significantly reduces macrophage infiltration and promotes a switch to the M2 macrophage phenotype and increasing regulatory T cells. Notably, the NLRP3 inflammasome pathway is activated in the kidneys of Ade‐CKD and decreases by KBL409. In primary kidney tubular epithelial cells treated with p‐cresyl sulfate, short‐chain fatty acids significantly increase M2 macrophage polarization factors and decrease profibrotic markers.
Conclusions
These results demonstrate that supplementation with the probiotic KBL409 has beneficial immunomodulating effects and protects against kidney injury.
Intestinal dysbiosis plays a significant role in the pathogenesis of chronic kidney disease. Supplementation of Lactobacillus acidophilus KBL409 ameliorates kidney function and fibrosis in adenine‐induced mice model of chronic kidney disease. This effect is mediated by restoration of intestinal barrier, modulation of systemic and renal inflammation, and increased production of short‐chain fatty acids. Therefore, KBL409 can be a potential therapeutic option to prevent progression of chronic kidney disease.
Functional van der Waals heterojunctions of transition metal dichalcogenides are emerging as a potential candidate for the basis of next‐generation logic devices and optoelectronics. However, the ...complexity of synthesis processes so far has delayed the successful integration of the heterostructure device array within a large scale, which is necessary for practical applications. Here, a direct synthesis method is introduced to fabricate an array of self‐assembled WSe2/MoS2 heterostructures through facile solution‐based directional precipitation. By manipulating the internal convection flow (i.e., Marangoni flow) of the solution, the WSe2 wires are selectively stacked over the MoS2 wires at a specific angle, which enables the formation of parallel‐ and cross‐aligned heterostructures. The realized WSe2/MoS2‐based p–n heterojunction shows not only high rectification (ideality factor: 1.18) but also promising optoelectrical properties with a high responsivity of 5.39 A W−1 and response speed of 16 µs. As a feasible application, a WSe2/MoS2‐based photodiode array (10 × 10) is demonstrated, which proves that the photosensing system can detect the position and intensity of an external light source. The solution‐based growth of hierarchical structures with various alignments could offer a method for the further development of large‐area electronic and optoelectronic applications.
A WSe2/MoS2‐based p–n heterostructure array is realized by a solution‐based direct growth method. WSe2 wires are selectively stacked over the MoS2 wires at the desired angle to form parallel‐ or cross‐aligned heterostructures over a large area. The p–n heterojunction array has a clean interface, resulting in outstanding rectification. Additionally, a prototype photosensing device with good photoresponsivity and response time is demonstrated.
Fiber electronics is a key research area for realizing wearable microelectronic devices. Significant progress has been made in recent years in developing the geometry and composition of electronic ...fibers. In this review, we present that recent progress in the architecture and electrical properties of electronic fibers, including their fabrication methods. We intensively investigate the structural designs of fiber-shaped devices: coaxial, twisted, three-dimensional layer-by-layer, and woven structures. In addition, we introduce remarkable applications of fiber-shaped devices for energy harvesting/storage, sensing, and light-emitting devices. Electronic fibers offer high potential for use in next-generation electronics, such as electronic textiles and smart integrated textile systems, which require excellent deformability and high operational reliability.
Abstract
Photophysical and photochemical properties of graphene quantum dots (GQDs) strongly depend on their morphological and chemical features. However, systematic and uniform manipulation of the ...chemical structures of GQDs remains challenging due to the difficulty in simultaneous control of competitive reactions, i.e., growth and doping, and the complicated post-purification processes. Here, we report an efficient and scalable production of chemically tailored N-doped GQDs (NGs) with high uniformity and crystallinity via a simple one-step solvent catalytic reaction for the thermolytic self-assembly of molecular precursors. We find that the graphitization of N-containing precursors during the formation of NGs can be modulated by intermolecular interaction with solvent molecules, the mechanism of wh ich is evidenced by theoretical calculations and various spectroscopic analyses. Given with the excellent visible-light photoresponse and photocatalytic activity of NGs, it is expected that the proposed approach will promote the practical utilization of GQDs for various applications in the near future.
Mesenchymal stem cell (MSC) is a promising tool for the therapy of immune disorders. However, their efficacy and mechanisms in treating allergic skin disorders are less verified. We sought to ...investigate the therapeutic efficacy of human umbilical cord blood-derived MSCs (hUCB-MSCs) against murine atopic dermatitis (AD) and to explore distinct mechanisms that regulate their efficacy. AD was induced in mice by the topical application of Dermatophagoides farinae. Naïve or activated-hUCB-MSCs were administered to mice, and clinical severity was determined. The subcutaneous administration of nucleotide-binding oligomerization domain 2 (NOD2)-activated hUCB-MSCs exhibited prominent protective effects against AD, and suppressed the infiltration and degranulation of mast cells (MCs). A β-hexosaminidase assay was performed to evaluate the effect of hUCB-MSCs on MC degranulation. NOD2-activated MSCs reduced the MC degranulation via NOD2-cyclooxygenase-2 signaling. In contrast to bone marrow-derived MSCs, hUCB-MSCs exerted a cell-to-cell contact-independent suppressive effect on MC degranulation through the higher production of prostaglandin E2 (PGE2 ). Additionally, transforming growth factor (TGF)-β1 production from hUCB-MSCs in response to interleukin-4 contributed to the attenuation of MC degranulation by downregulating FcεRI expression in MCs. In conclusion, the subcutaneous application of NOD2-activated hUCB-MSCs can efficiently ameliorate AD, and MSC-derived PGE2 and TGF-β1 are required for the inhibition of MC degranulation.
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