We introduce the concept and operation of a binding‐induced DNA nanomachine that can be activated by proteins and nucleic acids. This new type of nanomachine harnesses specific target binding to ...trigger assembly of separate DNA components that are otherwise unable to spontaneously assemble. Three‐dimensional DNA tracks of high density are constructed on gold nanoparticles functionalized with hundreds of single‐stranded oligonucleotides and tens of an affinity ligand. A DNA swing arm, free in solution, is linked to a second affinity ligand. Binding of a target molecule to the two ligands brings the swing arm to AuNP and initiates autonomous, stepwise movement of the swing arm around the AuNP surface. The movement of the swing arm, powered by enzymatic cleavage of conjugated oligonucleotides, cleaves hundreds of oligonucleotides in response to a single binding event. We demonstrate three nanomachines that are specifically activated by streptavidin, platelet‐derived growth factor, and the Smallpox gene. Substituting the ligands enables the nanomachine to respond to other molecules. The new nanomachines have several unique and advantageous features over DNA nanomachines that rely on DNA self‐assembly.
Binding of a target molecule to two ligands brings the swing arm to the gold nanoparticle (AuNP) and initiates autonomous, stepwise movement of the swing arm along the three‐dimensional DNA tracks on the AuNP surface. The movement of the swing arm, powered by enzymatic cleavage of DNA anchorages, cleaves hundreds of oligonucleotides in response to a single binding event.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
IncX4 plasmids are associated with the dissemination of the mcr-1 genes in Enterobacteriaceae. We screened IncX4 plasmids among 2,470 isolates of Enterobacteriaceae and determined the mcr-1 positive ...isolates. Forty-three isolates were observed to carry IncX4 type plasmid, among which 13 were identified to carry mcr-1 gene. Three representative mcr-1-positive IncX4 plasmids were selected for high-throughput sequencing. Comparative genomics showed that the mcr-1-carrying IncX4 plasmids exhibit remarkable similarity in the backbone, and the major distinction lies in the region containing mcr-1. The major variable regions of all the IncX4 plasmids were fully characterized by PCR-RFLP. The results revealed that the mcr-1 was located on the Variable Region I of IncX4 plasmids in 11 E. coli isolates. Among them, nine E. coli strains possess an epidemic pCSZ4-like IncX4 plasmid containing mcr-1. ISApl1 was presumably involved in the transposition of the mcr-1 cassette and then was lost. Similar genetic contexts were found in different plasmids, even the E. coli chromosome, implying the acquisition of mcr-1 by a unique common mechanism.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Abstract
The changes of broad emission lines should be a crucial issue in understanding the physical properties of changing-look active galactic nuclei (CL-AGNs). Here we present the results of an ...intensive and homogeneous 6 month long reverberation mapping (RM) monitoring campaign during a low-activity state of the CL-AGN Seyfert galaxy NGC 3516. Photometric and spectroscopic monitoring was carried out during 2018–2019 with the Lijiang 2.4 m telescope. The sampling is 2 days in most nights, and the average sampling is ∼3 days. The rest-frame time lags of H
α
and H
β
are
and
days, respectively. From an rms H
β
line dispersion of
σ
line
= 1713.3 ± 46.7 km s
−1
and a virial factor of
f
σ
= 5.5, the central black hole mass of NGC 3516 is estimated to be
, which is in agreement with previous estimates. The velocity-resolved delays show that the time lags increase toward negative velocity for both H
α
and H
β
. The velocity-resolved RM of H
α
is done for the first time. These RM results are consistent with other observations before the spectral-type change, indicating a basically constant broad-line region structure during the CL process. The CL model of changes of accretion rate seems to be favored by long-term H
β
variability and RM observations of NGC 3516.
Arsenic Binding to Proteins Shen, Shengwen; Li, Xing-Fang; Cullen, William R ...
Chemical reviews,
10/2013, Volume:
113, Issue:
10
Journal Article
Peer reviewed
Open access
An overview of how arsenic binds to proteins is presented from an analytical and biochemical perspective. The binding affinity, kinetics and speciation of arsenic binding are also investigated.
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IJS, KILJ, NUK, PNG, UL, UM
IMPORTANCE: Coronavirus disease 2019 (COVID-19) is a pandemic with no specific therapeutic agents and substantial mortality. It is critical to find new treatments. OBJECTIVE: To determine whether ...convalescent plasma transfusion may be beneficial in the treatment of critically ill patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. DESIGN, SETTING, AND PARTICIPANTS: Case series of 5 critically ill patients with laboratory-confirmed COVID-19 and acute respiratory distress syndrome (ARDS) who met the following criteria: severe pneumonia with rapid progression and continuously high viral load despite antiviral treatment; Pao2/Fio2 <300; and mechanical ventilation. All 5 were treated with convalescent plasma transfusion. The study was conducted at the infectious disease department, Shenzhen Third People's Hospital in Shenzhen, China, from January 20, 2020, to March 25, 2020; final date of follow-up was March 25, 2020. Clinical outcomes were compared before and after convalescent plasma transfusion. EXPOSURES: Patients received transfusion with convalescent plasma with a SARS-CoV-2–specific antibody (IgG) binding titer greater than 1:1000 (end point dilution titer, by enzyme-linked immunosorbent assay ELISA) and a neutralization titer greater than 40 (end point dilution titer) that had been obtained from 5 patients who recovered from COVID-19. Convalescent plasma was administered between 10 and 22 days after admission. MAIN OUTCOMES AND MEASURES: Changes of body temperature, Sequential Organ Failure Assessment (SOFA) score (range 0-24, with higher scores indicating more severe illness), Pao2/Fio2, viral load, serum antibody titer, routine blood biochemical index, ARDS, and ventilatory and extracorporeal membrane oxygenation (ECMO) supports before and after convalescent plasma transfusion. RESULTS: All 5 patients (age range, 36-65 years; 2 women) were receiving mechanical ventilation at the time of treatment and all had received antiviral agents and methylprednisolone. Following plasma transfusion, body temperature normalized within 3 days in 4 of 5 patients, the SOFA score decreased, and Pao2/Fio2 increased within 12 days (range, 172-276 before and 284-366 after). Viral loads also decreased and became negative within 12 days after the transfusion, and SARS-CoV-2–specific ELISA and neutralizing antibody titers increased following the transfusion (range, 40-60 before and 80-320 on day 7). ARDS resolved in 4 patients at 12 days after transfusion, and 3 patients were weaned from mechanical ventilation within 2 weeks of treatment. Of the 5 patients, 3 have been discharged from the hospital (length of stay: 53, 51, and 55 days), and 2 are in stable condition at 37 days after transfusion. CONCLUSIONS AND RELEVANCE: In this preliminary uncontrolled case series of 5 critically ill patients with COVID-19 and ARDS, administration of convalescent plasma containing neutralizing antibody was followed by improvement in their clinical status. The limited sample size and study design preclude a definitive statement about the potential effectiveness of this treatment, and these observations require evaluation in clinical trials.
Covalent organic frameworks (COFs) are constructed from the precise integration of small organic blocks into an extended, porous framework
via
covalent linkages. COFs can also be viewed as an organic ...solid consisting of a periodic array of one dimensional (1-D) channels. Although a wide range of applications have been envisioned for COFs, understanding the structure-property correlation at the level of chemical linkages, topology, pore size and functionality is needed to unlock the potential of these materials. Herein, we review some emerging applications of two-dimensional (2D) COFs in solid-state photoluminescence, stimuli-responsive COFs, gas storage, ion conduction and energy storage, and discuss the intricate design principles that enable these COFs to perform better than their building blocks or polymeric counterparts. Going beyond bulk 2D-COFs, molecular thin organic layers called COFene can be derived from the exfoliation of 2D COFs, generating new properties for applications in optoelectronic devices, catalysis and separation.
This review provides guidelines for the function-oriented synthesis of 2D COFs from 3D solids to 2D sheets.
Although various catalytic materials have emerged for hydrogen evolution reaction (HER), it remains crucial to develop intrinsically effective catalysts with minimum uses of expensive and scarce ...precious metals. Metallic glasses (MGs) or amorphous alloys show up as attractive HER catalysts, but have so far limited to material forms and compositions that result in high precious‐metal loadings. Here, an Ir25Ni33Ta42 MG nanofilm exhibiting high intrinsic activity and superior stability at an ultralow Ir loading of 8.14 µg cm−2 for HER in 0.5 m H2SO4 is reported. With an overpotential of 99 mV for a current density of 10 mA cm−2, a small Tafel slope of 35 mV dec−1, and high turnover frequencies of 1.76 and 19.3 H2 s−1 at 50 and 100 mV overpotentials, the glassy film is among the most intrinsically active HER catalysts, outcompetes any reported MG, representative sulfides, and phosphides, and compares favorably with other precious‐metal‐containing catalysts. The outstanding HER performance of the Ir25Ni33Ta42 MG film is attributed to the synergistic effect of the novel alloy system and amorphous structure, which may inspire the development of multicomponent alloys for heterogeneous catalysis.
An extremely flat low‐iridium‐content Ir25Ni33Ta42 metallic glass film with an ultralow Ir loading is presented as an intrinsically active and highly stable catalyst for the hydrogen evolution reaction (HER) in acids. This work provides a novel alloy system for HER in acids, and is helpful for the development of heterogeneous catalysts in multicomponent alloys.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The conversion of platform molecule 5-hydroxymethylfurfural (HMF) into many value-added derivatives has attracted significant interest. FDCA and its esters are important derivatives of HMF, which can ...be used as polyester monomers and pharmaceutical intermediates. In this paper, oxidative esterification of 5-HMF has been carried out by using homogeneous and heterogeneous PdCoBi/C catalysts under atmospheric oxygen. The effect of reaction conditions on product distribution has been studied under both homogeneous and heterogeneous catalytic conditions. The highest yields of oxidative esterification products are obtained at 93% and 96% by using homogeneous and heterogeneous PdCoBi/C catalysts, respectively. The catalysts are characterized by X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (XRD). The catalytic system has better compatibility according to the expansion of the substrate. A reaction mechanism is proposed, and recycle experiments are also conducted.
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Efficient and reliable energy storage systems are crucial for our modern society. Lithium-ion batteries (LIBs) with excellent performance are widely used in portable electronics and ...electric vehicles (EVs), but frequent fires and explosions limit their further and more widespread applications. This review summarizes aspects of LIB safety and discusses the related issues, strategies, and testing standards. Specifically, it begins with a brief introduction to LIB working principles and cell structures, and then provides an overview of the notorious thermal runaway, with an emphasis on the effects of mechanical, electrical, and thermal abuse. The following sections examine strategies for improving cell safety, including approaches through cell chemistry, cooling, and balancing, afterwards describing current safety standards and corresponding tests. The review concludes with insights into potential future developments and the prospects for safer LIBs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract We revisited the formula related to the overall tilt angle of a specimen using a side‐entry double‐tilt sample holder in a transmission electron microscope. Initially, we examined existing ...formulas in the literature for calculating the overall tilt angle. Subsequently, a new formula was derived, proven to better account for the actions of the double‐tilt holder, thereby providing improved accuracy in the calculation. This newly derived formula has been implemented in the Landyne software suite. Furthermore, we demonstrated the accuracy of the new formula through examples. Research Highlights A new formula has been derived to calculate overall tilt angles for side‐entry double‐tilt holders in TEM.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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