In this paper, the characterization and application of a chemically reduced graphene oxide modified glassy carbon (CR-GO/GC) electrode, a novel electrode system, for the preparation of ...electrochemical sensing and biosensing platform are proposed. Different kinds of important inorganic and organic electroactive compounds (i.e., probe molecule (potassium ferricyanide), free bases of DNA (guanine (G), adenine (A), thymine (T), and cytosine (C)), oxidase/dehydrogenase-related molecules (hydrogen peroxide (H2O2)/β-nicotinamide adenine dinucleotide (NADH)), neurotransmitters (dopamine (DA)), and other biological molecules (ascorbic acid (AA), uric acid (UA), and acetaminophen (APAP)) were employed to study their electrochemical responses at the CR-GO/GC electrode, which shows more favorable electron transfer kinetics than graphite modified glassy carbon (graphite/GC) and glassy carbon (GC) electrodes. The greatly enhanced electrochemical reactivity of the four free bases of DNA at the CR-GO/GC electrode compared with that at graphite/GC and GC electrodes makes the CR-GO/GC electrode a better choice for the electrochemical biosensing of four DNA bases in both the single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) at physiological pH without a prehydrolysis step. This allows us to detect a single-nucleotide polymorphism (SNP) site for short oligomers with a particular sequence at the CR-GO/GC electrode without any hybridization or labeling processes in this work, suggesting the potential applications of CR-GO in the label-free electrochemical detection of DNA hybridization or DNA damage for further research. Based on the greatly enhanced electrochemical reactivity of H2O2 and NADH at the CR-GO/GC electrode, CR-GO/GC electrode-based bioelectrodes (in connection with glucose oxidase (GOD) and alcohol dehydrogenase (ADH)) show a better analytical performance for the detection of glucose and ethanol compared with graphite/GC- or GC-based bioelectrodes. By comparing the electrochemical performance of CR-GO with that of the conventional graphite and GC, we reveal that CR-GO with the nature of a single sheet showing favorable electrochemical activity should be a kind of more robust and advanced carbon electrode material which may hold great promise for electrochemical sensors and biosensors design.
Histone lysine acetylation and methylation have an important role during gene transcription in a chromatin context. Knowledge concerning the types of protein modules that can interact with ...acetyl-lysine has so far been limited to bromodomains. Recently, a tandem plant homeodomain (PHD) finger (PHD1-PHD2, or PHD12) of human DPF3b, which functions in association with the BAF chromatin remodelling complex to initiate gene transcription during heart and muscle development, was reported to bind histones H3 and H4 in an acetylation-sensitive manner, making it the first alternative to bromodomains for acetyl-lysine binding. Here we report the structural mechanism of acetylated histone binding by the double PHD fingers of DPF3b. Our three-dimensional solution structures and biochemical analysis of DPF3b highlight the molecular basis of the integrated tandem PHD finger, which acts as one functional unit in the sequence-specific recognition of lysine-14-acetylated histone H3 (H3K14ac). Whereas the interaction with H3 is promoted by acetylation at lysine 14, it is inhibited by methylation at lysine 4, and these opposing influences are important during transcriptional activation of the mouse DPF3b target genes Pitx2 and Jmjd1c. Binding of this tandem protein module to chromatin can thus be regulated by different histone modifications during the initiation of gene transcription.
Phosphorescence shows great potential for application in bioimaging and ion detection because of its long-lived luminescence and high signal-to-noise ratio, but establishing phosphorescence emission ...in aqueous environments remains a challenge. Herein, we present a general design strategy that effectively promotes phosphorescence by utilising water molecules to construct hydrogen-bonded networks between carbon dots (CDs) and cyanuric acid (CA). Interestingly, water molecules not only cause no phosphorescence quenching but also greatly enhance the phosphorescence emission. This enhancement behaviour can be explained by the fact that the highly ordered bound water on the CA particle surface can construct robust bridge-like hydrogen-bonded networks between the CDs and CA, which not only effectively rigidifies the C=O bonds of the CDs but also greatly enhances the rigidity of the entire system. In addition, the CD-CA suspension exhibits a high phosphorescence lifetime (687 ms) and is successfully applied in ion detection based on its visible phosphorescence.
In materials chiral fermions such as Weyl fermions are characterized by nonzero chiral charges, which are singular points of Berry curvature in momentum space. Recently, new types of chiral fermions ...beyond Weyl fermions have been discovered in structurally chiral crystals CoSi, RhSi and PtAl. Here, we have synthesized RhSn single crystals, which have opposite structural chirality to the CoSi crystals we previously studied. Using angle-resolved photoemission spectroscopy, we show that the bulk electronic structures of RhSn are consistent with the band calculations and observe evident surface Fermi arcs and helical surface bands, confirming the existence of chiral fermions in RhSn. It is noteworthy that the helical surface bands of the RhSn and CoSi crystals have opposite handedness, meaning that the chiral fermions are reversed in the crystals of opposite structural chirality. Our discovery establishes a direct connection between chiral fermions in momentum space and chiral lattices in real space.
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•Acetyl-lysine and methyl-lysine reader domains are promising drug targets.•Major accomplishments made in chemical modulation of BET family bromodomains.•What is the progress made in ...non-BET chemical modulators?•What are the advances in chemical modulators of methyl-lysine reader domains?
Site-specific lysine acetylation and methylation on histones are critical post-translational modifications (PTMs) that govern ordered gene transcription in chromatin. Mis-regulation of these histone PTM-mediated processes has been shown to be associated with human diseases. Since the 2010 landmark reports of small molecules (+)-JQ1 and I-BET762 that target the acetyl-lysine ‘reader’ Bromodomain and Extra Terminal domain (BET) proteins, there have been relentless efforts to develop epigenetic therapy with small molecules to modulate molecular interactions of epigenome reader domain proteins with PTMs. In addition to BET, the other emerging targets include non-BET acetyl-lysine and methyl-lysine reader domains. This review covers the key chemical modulators of the aforementioned epigenome reader proteins.
The key issue holding back the application of solid polymeric electrolytes in high‐energy density lithium metal batteries is the contradictory requirements of high ion conductivity and mechanical ...stability. In this work, self‐healable solid polymeric electrolytes (SHSPEs) with rigid‐flexible backbones and high ion conductivity are synthesized by a facile condensation polymerization approach. The all‐solid Li metal full batteries based on the SHSPEs possess freely bending flexibility and stable cycling performance as a result of the more disciplined metal Li plating/stripping, which have great implications as long‐lifespan energy sources compatible with other wearable devices.
Solid but flexible: A self‐healing solid polymer electrolyte (featuring fast self‐healing within 60 s after a deep cut with a blade) endows solid Li metal full batteries with freely bending flexibility and superior cycling stability as demonstrated by the small capacity decay of 0.1 % per cycle over 100 cycles.
Lipophilic marine toxins in shellfish pose significant threats to the health of seafood consumers. To assess the contamination status of shellfish by lipophilic marine toxins in the Bohai Sea, nine ...species of shellfish periodically collected from five representative aquaculture zones throughout a year were analyzed with a method of liquid chromatography-tandem mass spectrometry (LC–MS/MS). Lipophilic marine toxins, including okadaic acid (OA), dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2), yessotoxin (YTX), homo-yessotoxin (homo-YTX), azaspiracids (AZA2 and AZA3), gymnodimine (GYM), and 13-desmethyl spirolide C (13-DesMe-C), were detected in more than 95 percent of the shellfish samples. Toxins PTX2, YTX, 13-DesMe-C and GYM were predominant components detected in shellfish samples. Scallops, clams and mussels accumulated much higher level of lipophilic marine toxins compared to oysters. Toxin content in shellfish samples collected from different sampling locations showed site-specific seasonal variation patterns. High level of toxins was found during the stages from December to February and June to July in Hangu, while from March to April and August to September in Laishan. Some toxic algae, including Dinophysis acuminata, D. fortii, Prorocentrum lima, Gonyaulax spinifera and Lingulodinium polyedrum, were identified as potential origins of lipophilic marine toxins in the Bohai Sea. The results will offer a sound basis for monitoring marine toxins and protecting the health of seafood consumers.
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•Shellfish samples were monthly collected from aquaculture zones in the Bohai Sea.•Lipophilic phycotoxins in shellfish were analyzed using HPLC-MS/MS combined with SPE.•Lipophilic phycotoxins could be detected in 104 out of 110 shellfish samples.•PTX2, YTX, SPX1 and GYM were predominated in shellfish samples from the Bohai Sea.•Scallop, clam and mussel were easily contaminated by lipophilic phycotoxins.
A wide array of lipophilic marine toxins were detected in shellfish samples from the Bohai Sea, which constitute an emerging pollution issue in this region.
With the increasing use of real-time synchronized phasor measurement units, it is necessary to consider applications of these measurements in greater detail. One of the most natural applications of ...these measurements is in the area of state estimation. A straightforward application of state estimation theory treats phasor measurements of currents and voltages as additional measurements to be appended to traditional measurements now being used in most energy management system (EMS) state estimators. The resulting state estimator is once again nonlinear and requires significant modifications to existing EMS software. This paper proposes an alternative approach, which leaves the traditional state estimation software in place, and discusses a novel method of incorporating the phasor measurements and the results of the traditional state estimator in a postprocessing linear estimator. This paper presents the underlying theory and provides verification through simulations of the two alternative strategies. It is shown that the new technique provides the same results as the nonlinear state estimator and does not require modification of the existing EMS software
Phosphatidylcholine (PC) is the most abundant phospholipid in eukaryotic cell membranes. In eukaryotes, two highly homologous enzymes, cholinephosphotransferase-1 (CHPT1) and choline/ethanolamine ...phosphotransferase-1 (CEPT1) catalyze the final step of de novo PC synthesis. CHPT1/CEPT1 joins two substrates, cytidine diphosphate-choline (CDP-choline) and diacylglycerol (DAG), to produce PC, and Mg
is required for the reaction. However, mechanisms of substrate recognition and catalysis remain unresolved. Here we report structures of a CHPT1 from Xenopus laevis (xlCHPT1) determined by cryo-electron microscopy to an overall resolution of ~3.2 Å. xlCHPT1 forms a homodimer, and each protomer has 10 transmembrane helices (TMs). The first 6 TMs carve out a cone-shaped enclosure in the membrane in which the catalysis occurs. The enclosure opens to the cytosolic side, where a CDP-choline and two Mg
are coordinated. The structures identify a catalytic site unique to eukaryotic CHPT1/CEPT1 and suggest an entryway for DAG. The structures also reveal an internal pseudo two-fold symmetry between TM3-6 and TM7-10, and suggest that CHPT1/CEPT1 may have evolved from their distant prokaryotic ancestors through gene duplication.
Highlights
The CuS@rGO composite aerogel can achieve the broad effective absorption bandwidth (EAB) of 8.44 GHz with the filler content of 6 wt%.
The RL
min
of CuS@rGO composite aerogel is -55.1 dB ...and EAB is 7.2 GHz with the filler content of 2 wt% by ascorbic acid thermal reduction. The radar cross-section reduction value of CuS@rGO composite aerogel can reach 53.3 dB m
2
.
The CuS@rGO composite aerogels possess lightweight, compression and recovery, radar-infrared compatible stealth properties.
Developing ultrabroad radar-infrared compatible stealth materials has turned into a research hotspot, which is still a problem to be solved. Herein, the copper sulfide wrapped by reduced graphene oxide to obtain three-dimensional (3D) porous network composite aerogels (CuS@rGO) were synthesized via thermal reduction ways (hydrothermal, ascorbic acid reduction) and freeze-drying strategy. It was discovered that the phase components (rGO and CuS phases) and micro/nano structure (microporous and nanosheet) were well-modified by modulating the additive amounts of CuS and changing the reduction ways, which resulted in the variation of the pore structure, defects, complex permittivity, microwave absorption, radar cross section (RCS) reduction value and infrared (IR) emissivity. Notably, the obtained CuS@rGO aerogels with a single dielectric loss type can achieve an ultrabroad bandwidth of 8.44 GHz at 2.8 mm with the low filler content of 6 wt% by a hydrothermal method. Besides, the composite aerogel via the ascorbic acid reduction realizes the minimum reflection loss (RL
min
) of − 60.3 dB with the lower filler content of 2 wt%. The RCS reduction value can reach 53.3 dB m
2
, which effectively reduces the probability of the target being detected by the radar detector. Furthermore, the laminated porous architecture and multicomponent endowed composite aerogels with thermal insulation and IR stealth versatility. Thus, this work offers a facile method to design and develop porous rGO-based composite aerogel absorbers with radar-IR compatible stealth.
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