The COVID‐19 pandemic has rapidly evolved and changed our way of life in an unprecedented manner. The emergence of COVID‐19 has impacted transplantation worldwide. The impact has not been just ...restricted to issues pertaining to donors or recipients, but also health‐care resource utilization as the intensity of cases in certain jurisdictions exceeds available capacity. Here we provide a personal viewpoint representing different jurisdictions from around the world in order to outline the impact of the current COVID‐19 pandemic on organ transplantation. Based on our collective experience, we discuss mitigation strategies such as donor screening, resource planning, and a staged approach to transplant volume considerations as local resource issues demand. We also discuss issues related to transplant‐related research during the pandemic, the role of transplant infectious diseases, and the influence of transplant societies for education and disseminating current information.
The authors discuss the impact of COVID‐19 on donation and transplantation and provide a global framework for donor screening and management of transplant activity during the pandemic.
Manipulation of grain boundaries in polycrystalline perovskite is an essential consideration for both the optoelectronic properties and environmental stability of solar cells as the ...solution-processing of perovskite films inevitably introduces many defects at grain boundaries. Though small molecule-based additives have proven to be effective defect passivating agents, their high volatility and diffusivity cannot render perovskite films robust enough against harsh environments. Here we suggest design rules for effective molecules by considering their molecular structure. From these, we introduce a strategy to form macromolecular intermediate phases using long chain polymers, which leads to the formation of a polymer-perovskite composite cross-linker. The cross-linker functions to bridge the perovskite grains, minimizing grain-to-grain electrical decoupling and yielding excellent environmental stability against moisture, light, and heat, which has not been attainable with small molecule defect passivating agents. Consequently, all photovoltaic parameters are significantly enhanced in the solar cells and the devices also show excellent stability.
The development of various flexible and stretchable materials has attracted interest for promising applications in biomedical engineering and electronics industries. This interest in wearable ...electronics, stretchable circuits, and flexible displays has created a demand for stable, easily manufactured, and cheap materials. However, the construction of flexible and elastic electronics, on which commercial electronic components can be mounted through simple and cost-effective processing, remains challenging. We have developed a nanocomposite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) elastomer. To achieve uniform distributions of CNTs within the polymer, an optimized dispersion process was developed using isopropyl alcohol (IPA) and methyl-terminated PDMS in combination with ultrasonication. After vaporizing the IPA, various shapes and sizes can be easily created with the nanocomposite, depending on the mold. The material provides high flexibility, elasticity, and electrical conductivity without requiring a sandwich structure. It is also biocompatible and mechanically stable, as demonstrated by cytotoxicity assays and cyclic strain tests (over 10,000 times). We demonstrate the potential for the healthcare field through strain sensor, flexible electric circuits, and biopotential measurements such as EEG, ECG, and EMG. This simple and cost-effective fabrication method for CNT/PDMS composites provides a promising process and material for various applications of wearable electronics.
Epidermal electronics are extensively explored as an important platform for future biomedical engineering. Epidermal devices are typically fabricated using high‐cost methods employing complex vacuum ...microfabrication processes, limiting their widespread potential in wearable electronics. Here, a low‐cost, solution‐based approach using electroconductive reduced graphene oxide (RGO) sheets on elastic and porous poly(dimethylsiloxane) (PDMS) thin films for multifunctional, high‐performance, graphene‐based epidermal bioelectrodes and strain sensors is presented. These devices are fabricated employing simple coatings and direct patterning without using any complicated microfabrication processes. The graphene bioelectrodes show a superior stretchability (up to 150% strain), with mechanical durability up to 5000 cycles of stretching and releasing, and low sheet resistance (1.5 kΩ per square), and the graphene strain sensors exhibit a high sensitivity (a gauge factor of 7 to 173) with a wide sensing range (up to 40% strain). Fully functional applications of dry bioelectrodes in monitoring human electrophysiological signals (i.e., electrocardiogram, electroencephalography, and electromyogram) and highly sensitive strain sensors for precise detection of large‐scale human motions are demonstrated. It is believed that our unique processing capability and multifunctional device platform based on RGO/porous PDMS will pave the way for low‐cost processing and integration of 2D materials for future wearable electronic skin.
A solution‐based approach using electroconductive reduced graphene oxide sheets on elastic and porous PDMS thin films for multifunctional, high‐performance, graphene‐based epidermal bioelectrode/strain sensors is presented. Fully functional applications of bioelectrodes in monitoring electrophysiological signals using human and strain sensors for precisely detecting large‐scale human motions are demonstrated.
The inability to guide the nucleation locations of electrochemically deposited Li has long been considered the main factor limiting the utilization of high‐energy‐density Li‐metal batteries. In this ...study, an electrical conductivity gradient interfacial host comprising 1D high conductivity copper nanowires and nanocellulose insulating layers is used in stable Li‐metal anodes. The conductivity gradient system guides the nucleation sites of Li‐metal to be directed during electrochemical plating. Additionally, the controlled parameter of the intermediate layer affects the highly stable Li‐metal plating. The electrochemical behavior is confirmed through experiments associated with the COMSOL Multiphysics simulation data. The distributed Li‐ion reaction flux resulting from the controlled electrical conductivity enables stable cycling for more than 250 cycles at 1 mA cm−2. The gradient system effectively suppresses dendrite growth even at a high current density of 5 mA cm−2 and ensures Li plating and stripping with ultra‐long‐term stability. To demonstrate the high‐energy‐density full‐cell application of the developed anode, it is paired with the LiNi0.8Co0.1Mn0.1O2 cathode. The cells demonstrate a high capacity retention of 90% with an extremely high Coulombic efficiency of 99.8% over 100 cycles. These results shed light on the formidable challenges involved in exploiting the engineering aspects of high‐energy‐density Li‐metal batteries.
An electrical conductivity gradient interfacial host composed of simply fabricated 1D high conductivity copper nanowires and nanocellulose insulating layers shows stable lithium metal plating/stripping during electrochemical reaction. The conductivity gradient offers to guide the nucleation of lithium metal deposition, resulting in a high capacity retention of 90% with an extremely high Coulombic efficiency of 99.8% over 100 cycles as a full‐cell test.
5 mm‐scale large FAPbI 3 single crystals and corresponding photoconductive properties are shown. The phase transition of FAPbI3 between the α‐phase and δ‐phase is studied. The carrier mobility is 4.4 ...cm2 V−1 s−1 with a lifetime of 484 ns in the bulk of the single crystal. Finally, photodetectors based on single‐crystal FAPbI3 are demonstrated.
Amino acids are required for activation of the mammalian target of rapamycin (mTOR) kinase, which regulates protein translation, cell size, and autophagy. However, the amino acid sensor that directly ...couples intracellular amino acid-mediated signaling to mTORC1 is unknown. Here we show that leucyl-tRNA synthetase (LRS) plays a critical role in amino acid-induced mTORC1 activation by sensing intracellular leucine concentration and initiating molecular events leading to mTORC1 activation. Mutation of LRS amino acid residues important for leucine binding renders the mTORC1 pathway insensitive to intracellular levels of amino acids. We show that LRS directly binds to Rag GTPase, the mediator of amino acid signaling to mTORC1, in an amino acid-dependent manner and functions as a GTPase-activating protein (GAP) for Rag GTPase to activate mTORC1. This work demonstrates that LRS is a key mediator for amino acid signaling to mTORC1.
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► Leucyl-tRNA synthetase (LRS) senses leucine for mTORC1 signaling ► mTORC1 activity, lysosomal localization, cell size, and autophagy are regulated by LRS ► LRS acts as GTPase-activating protein (GAP) for RagD GTPase, an mTORC1 regulator ► The interaction between LRS and RagD GTPase is amino acid dependent
In response to leucine, leucyl-tRNA synthetase activates the mTORC1 pathway by acting as a GTPase-activating protein for a component of mTORC1. The findings reveal a mechanism for transducing amino acid availability to TOR signaling.
The land-use change from natural to managed farmland ecosystems can undergo perturbations and significantly impact soil environment and communities. To understand how anthropogenic land-use ...alteration determines in-depth relationships among soil environmental factors and soil bacterial communities, high-resolution characterization was performed using soil samples (27 spots × 3 depths; top 10–20 cm, middle 90–100 cm, bottom 180–190 cm) from a natural forest and a 50 year-old farmland. The soil bacterial community abundance (number of OTU's per sample) and diversity (Faith's phylogenetic diversity) was significantly higher in the top layer of farmland soil than in forest soil. However, the differences in bacterial community abundance between farmland and forest decreased with depth, suggesting that the effect of fertilization was limited to top and middle layers. The phyla Acidobacteria and Proteobacteria were distributed distinctively during the land-use change. The subgroups Gp1–3 of Acidobacteria were more abundant in the forest samples (pH 3.5–5), while Gp4–7 and Gp10 were predominant in the farmland (pH 4.5–9.5). Members belonging to α-Proteobacteria and Xanthomonadales in γ–Proteobacteria were dominant in the forest, whereas β–, δ–, and γ–Proteobacteria were relatively abundant in the farmland. Both multivariate and correlation network analyses revealed that Acidobacteria and Proteobacteria communities were significantly affected by soil pH, as well as toxic metals from pesticides (Zn, Cr, Ni, Cu, Cd, As) and terminal electron acceptors (NO3, bioavailable Fe(III), SO4). In line with the long history of anthropogenic fertilization, the farmland site showed high abundance of membrane and ATP-binding cassette transporter genes, suggesting the key for uptake of nutrients and for protection against toxic metals and environmental stresses. This study provides new insights into the use of both Acidobacteria and Proteobacteria community structures as a bacterial indicator for land-use change.
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•High-resolution data of 16S rRNA sequencing and environmental factors were analyzed.•Land-use change from forest to farmland caused changes in pH, nutrients, anthropogenic metals, and TEAs.•Acidobacteria and Proteobacteria were most affected by land-use change.•Physicochemical variations had close associations with specific subgroups of these phyla.•These specific subgroups can be good bioindicators associated with land-use change.
Pseudomonas aeruginosa is a well-known pathogenic bacterium that forms biofilms and produces virulence factors via quorum sensing (QS). Interfering with normal QS interactions between signal ...molecules and their cognate receptors is a developing strategy for attenuating its virulence. Here we tested the hypothesis that 6-gingerol, a pungent oil of fresh ginger, reduces biofilm formation and virulence by antagonistically binding to P. aeruginosa QS receptors. In silico studies demonstrated molecular binding occurs between 6-gingerol and the QS receptor LasR through hydrogen bonding and hydrophobic interactions. Experimentally 6-gingerol reduced biofilm formation, several virulence factors (e.g., exoprotease, rhamnolipid, and pyocyanin), and mice mortality. Further transcriptome analyses demonstrated that 6-gingerol successfully repressed QS-induced genes, specifically those related to the production of virulence factors. These results strongly support our hypothesis and offer insight into the molecular mechanism that caused QS gene repression.
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