Geometric and Electronic Engineering of Atomically Dispersed Copper-Cobalt Diatomic Sites for Synergistic Promotion of Bifunctional Oxygen Electrocatalysis in Zinc-Air Batteries.

The development of rechargeable zinc-air batteries is heavily dependent on bifunctional oxygen electrocatalysts to offer exceptional oxygen reduction/evolution reaction (ORR/OER) activities. However, the design of such electrocatalysts with high activity and durability is challenging. Herein, a strategy is proposed to create an electrocatalyst comprised of copper-cobalt diatomic sites on a highly porous nitrogen-doped carbon matrix (Cu-Co/NC) with abundantly accessible metal sites and optimal geometric and electronic structures. Experimental findings and theoretical calculations demonstrate that the synergistic effect of Cu-Co dual-metal sites with metal-N4 coordination induce asymmetric charge distributions with moderate adsorption/desorption behavior with oxygen intermediates. This electrocatalyst exhibits extraordinary bifunctional oxygen electrocatalytic activities in alkaline media, with a half-wave potential of 0.92 V for ORR and a low overpotential of 335 mV at 10 mA cm-2 for OER. In addition, it demonstrates exceptional ORR activity in acidic (0.85 V) and neutral (0.74 V) media. When applied to a zinc-air battery, it achieves extraordinary operational performance and outstanding durability (510 h), ranking it as one of the most efficient bifunctional electrocatalysts reported to date. This work demonstrates the importance of geometric and electronic engineering of isolated dual-metal sites for boosting bifunctional electrocatalytic activity in electrochemical energy devices.

Engineering the Electronic Structure of Single-Atom Iron Sites with Boosted Oxygen Bifunctional Activity for Zinc-Air Batteries.

Rechargeable zinc-air batteries typically require efficient, durable, and inexpensive bifunctional electrocatalysts to support oxygen reduction/evolution reactions (ORR/OER). However, sluggish kinetics and mass transportation challenges must be addressed if the performance of these catalysts is to be enhanced. Herein, a strategy to fabricate a catalyst comprising atomically dispersed iron atoms supported on a mesoporous nitrogen-doped carbon support (Fe SAs/NC) with accessible metal sites and optimized electronic metal-support interactions is developed. Both the experimental results and theoretical calculations reveal that the engineered electronic structures of the metal active sites can regulate the charge distribution of Fe centers to optimize the adsorption/desorption of oxygenated intermediates. The Fe SAs/NC containing Fe1 N4 O1 sites achieves remarkable ORR activity over the entire pH range, with half-wave potentials of 0.93, 0.83, and 0.75 V (vs reversible hydrogen electrode) in alkaline, acidic, and neutral electrolytes, respectively. In addition, it demonstrates a promising low overpotential of 320 mV at 10 mA cm-2 for OER in alkaline conditions. The zinc-air battery assembled with Fe SAs/NC exhibits superior performance than that of Pt/C+RuO2 counterpart in terms of peak power density, specific capacity, and cycling stability. These findings demonstrate the importance of the electronic structure engineering of metal sites in directing catalytic activity.

Low-power flexible organic memristor based on PEDOT:PSS/pentacene heterojunction for artificial synapse.

Organic synaptic memristors are of considerable interest owing to their attractive characteristics and potential applications to flexible neuromorphic electronics. In this work, an organic type-II heterojunction consisting of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and pentacene was adopted for low-voltage and flexible memristors. The conjugated polymer PEDOT:PSS serves as the flexible resistive switching (RS) layer, while the thin pentacene layer plays the role of barrier adjustment. This heterojunction enabled the memristor device to be triggered with low-energy RS operations (V < ± 1.0 V and I < 9.0 µA), and simultaneously providing high mechanical bending stability (bending radius of ≈2.5 mm, bending times = 1,000). Various synaptic properties have been successfully mimicked. Moreover, the memristors presented good potentiation/depression stability with a low cycle-to-cycle variation (CCV) of less than 8%. The artificial neural network consisting of this flexible memristor exhibited a high accuracy of 89.0% for the learning with MNIST data sets, even after 1,000 tests of 2.5% stress-strain. This study paves the way for developing low-power and flexible synaptic devices utilizing organic heterojunctions.

Leukemia derived dendritic cell (DCleu) mediated immune response goes along with reduced (leukemia-specific) regulatory T-cells.

The blastmodulatory Kit-M, composed of granulocyte-macrophage colony-stimulating-factor (GM-CSF) and Prostaglandin E1 (PGE1), is known to convert myeloid leukaemic blasts (from AML patients) into leukaemia derived dendritic cells (DCleu), which activate immunoreactive cells to gain antileukemic/leukaemia-specific activity. In this study we had a special focus on the influence of Kit-M treated, DC/DCleu containing patients'whole blood (WB, n = 16) on the provision of immunosuppressive regulatory T-cells. We could confirm that Kit-M significantly increased frequencies of (mature) dendritic cells (DC) and DCleu from leukemic whole blood (WB) without induction of blast proliferation. After mixed lymphocyte culture (MLC) with patients' T-cells we confirmed that DCleu mediated leukemia-specific responses- going along with activated and leukemia-specific T- and NK-cells in an intracellular cytokine staining assay (ICS) and a degranulation assay (Deg)- resulted in an increased anti-leukemic cytotoxicity (Cytotoxicity Fluorolysis Assay = CTX). We could demonstrate that (leukemia-specific) CD4+ and CD8+ regulatory T-cell population (Treg) decreased significantly after MLC compared to controls. We found significant positive correlations of leukemia-specific CD3+CD4+ cells with frequencies of (mature) DCleu. Achieved anti-leukemic cytotoxicity correlated significantly positive with leukemia-specific CD3+CD8+ cells and significantly negatively with (leukemia-specific) Treg. In summary we demonstrate that immunesuppressive (leukemia-specific) regulatory T-cells are significantly downregulated after Kit-M triggered MLC- going along with a (reinstalled) antileukemic reactivity of the immune system (as demonstrated with functional assays ICS, Deg, CTX).

Molecular Insights Into Neutrophil Biology From the Zebrafish Perspective: Lessons From CD18 Deficiency.

Neutrophils are key players in innate immunity and originate from the bone marrow of the adult mammalian organism. In mammals, mature neutrophils are released from the bone marrow into the peripheral blood where they circulate until their recruitment to sites of inflammation in a multistep adhesion cascade. Here, adhesion molecules of the ß2 integrin family (CD11/CD18) are critically required for the initial neutrophil adhesion to the inflamed endothelium and several post-adhesion steps allowing their extravasation into the inflamed tissue. Within the mammalian tissue, interstitial neutrophil migration can occur widely independent of ß2 integrins. This is in sharp contrast to neutrophil recruitment in zebrafish larvae (Danio rerio) where neutrophils originate from the caudal hematopoietic tissue and mainly migrate interstitially to sites of lesion upon the early onset of inflammation. However, neutrophils extravasate from the circulation to the inflamed tissue in zebrafish larvae at later-time points. Although zebrafish larvae are a widely accepted model system to analyze neutrophil trafficking in vivo, the functional impact of ß2 integrins for neutrophil trafficking during acute inflammation is completely unknown in this model. In this study, we generated zebrafish with a genetic deletion of CD18, the ß subunit of ß2 integrins, using CRISPR/Cas9 technology. Sequence alignments demonstrated a high similarity of the amino acid sequences between zebrafish and human CD18 especially in the functionally relevant I-like domain. In addition, the cytoplasmic domain of CD18 harbors two highly conserved NXXF motifs suggesting that zebrafish CD18 may share functional properties of human CD18. Accordingly, CD18 knock-out (KO) zebrafish larvae displayed the key symptoms of patients suffering from leukocyte adhesion deficiency (LAD) type I due to defects in ITGB2, the gene for CD18. Importantly, CD18 KO zebrafish larvae showed reduced neutrophil trafficking to sites of sterile inflammation despite the fact that an increased number of neutrophils was detectable in the circulation. By demonstrating the functional importance of CD18 for neutrophil trafficking in zebrafish larvae, our findings shed new light on neutrophil biology in vertebrates and introduce a new model organism for studying LAD type I.

Energy Modeling of Neighbor Discovery in Bluetooth Low Energy Networks.

Given that current Internet of Things (IoT) applications employ many different sensors to provide information, a large number of the Bluetooth low energy (BLE) devices will be developed for IoT systems. Developing low-power and low-cost BLE advertisers is one of most challenging tasks for supporting the neighbor discovery process (NDP) of such a large number of BLE devices. Since the parameter setting is essential to achieve the required performance for the NDP, an energy model of neighbor discovery in BLE networks can provide beneficial guidance when determining some significant parameter metrics, such as the advertising interval, scan interval, and scan window. In this paper, we propose a new analytical model to characterize the energy consumption using all possible parameter settings during the NDP in BLE networks. In this model, the energy consumption is derived based on the Chinese remainder theorem (CRT) for an advertising event and a scanning event during the BLE NDP. In addition, a real testbed is set up to measure the energy consumption. The measurement and experimental results reveal the relationship between the average energy consumption and the key parameters. On the basis of this model, beneficial guidelines for BLE network configuration are presented to help choose the proper parameters to optimize the power consumption for a given IoT application.

MiR-204 acts as a potential therapeutic target in acute myeloid leukemia by increasing BIRC6-mediated apoptosis.

Acute myeloid leukemia (AML) is one of the most common hematological malignancies all around the world. MicroRNAs have been determined to contribute various cancers initiation and progression, including AML. Although microRNA-204 (miR-204) exerts anti-tumor effects in several kinds of cancers, its function in AML remains unknown. In the present study, we assessed miR-204 expression in AML blood samples and cell lines. We also investigated the effects of miR-204 on cellular function of AML cells and the underlying mechanisms of the action of miR-204. Our results showed that miR-204 expression was significantly downregulated in AML tissues and cell lines. In addition, overexpression of miR-204 induced growth inhibition and apoptosis in AML cells, including AML5, HL-60, Kasumi-1 and U937 cells. Cell cycle analysis further confirmed an augmentation in theapoptotic subG1 population by miR-204 overexpression. Mechanistically, baculoviral inhibition of apoptosis protein repeat containing 6 (BIRC6) was identified as a direct target of miR-204. Enforcing miR-204 expression increased the luciferase activity and expression of BIRC6, as well as p53 and Bax expression. Moreover, restoration of BIRC6 reversed the pro-apoptotic effects of miR-204 overexpression in AML cells. Taken together, this study demonstrates that miR-204 causes AML cell apoptosis by targeting BIRC6, suggesting miR-204 may play an anti-carcinogenic role in AML and function as a novel biomarker and therapeutic target for the treatment of this disease. [BMB Reports 2018; 51(9): 444-449].