Designing effective electrocatalysts for the carbon dioxide reduction reaction (CO2RR) is an appealing approach to tackling the challenges posed by rising CO2 levels and realizing a closed carbon ...cycle. However, fundamental understanding of the complicated CO2RR mechanism in CO2 electrocatalysis is still lacking because model systems are limited. We have designed a model nickel single‐atom catalyst (Ni SAC) with a uniform structure and well‐defined Ni‐N4 moiety on a conductive carbon support with which to explore the electrochemical CO2RR. Operando X‐ray absorption near‐edge structure spectroscopy, Raman spectroscopy, and near‐ambient X‐ray photoelectron spectroscopy, revealed that Ni+ in the Ni SAC was highly active for CO2 activation, and functioned as an authentic catalytically active site for the CO2RR. Furthermore, through combination with a kinetics study, the rate‐determining step of the CO2RR was determined to be *CO2−+H+→*COOH. This study tackles the four challenges faced by the CO2RR; namely, activity, selectivity, stability, and dynamics.
Ni‐che reaction: In situ reduction of nickel(II) 2,9,16,23‐tetra(amino)phthalocyanine, anchored on the surface of carbon nanotubes, yields nickel single atoms. Advanced spectroscopy of the single‐atom catalyst reveals that Ni+ is a highly active catalytic site for CO2 activation and reduction.
The binding strength of reactive intermediates with catalytically active sites plays a crucial role in governing catalytic performance of electrocatalysts. NiFe hydroxide offers efficient oxygen ...evolution reaction (OER) catalysis in alkaline electrolyte, however weak binding of oxygenated intermediates on NiFe hydroxide still badly limits its catalytic activity. Now, a facile ball‐milling method was developed to enhance binding strength of NiFe hydroxide to oxygenated intermediates via generating tensile strain, which reduced the anti‐bonding filling states in the d orbital and thus facilitated oxygenated intermediates adsorption. The NiFe hydroxide with tensile strain increasing after ball‐milling exhibits an OER onset potential as low as 1.44 V (vs. reversible hydrogen electrode) and requires only a 270 mV overpotential to reach a water oxidation current density of 10 mA cm−2.
NiFe hydroxide was treated by ball‐milling to enhance its binding strength to an oxygenated intermediate. The prepared NiFe hydroxide that has induced tension shows excellent oxygen evolution performance.
The objective of change-point detection is to discover abrupt property changes lying behind time-series data. In this paper, we present a novel statistical change-point detection algorithm based on ...non-parametric divergence estimation between time-series samples from two retrospective segments. Our method uses the relative Pearson divergence as a divergence measure, and it is accurately and efficiently estimated by a method of direct density-ratio estimation. Through experiments on artificial and real-world datasets including human-activity sensing, speech, and Twitter messages, we demonstrate the usefulness of the proposed method.
Due to the increasing concerns on environmental pollution, fossil energy shortage, and sustainable development, the recycling of industrial by-products had become a popular practice worldwide. ...Chemical stabilization of problematic soils with biomass by-product lignin was being considered as one of the viable answers to the consumption of such lignin stockpiles and the reduction of environmental loading. This paper summarized the production and physicochemical properties of by-product lignin collected from paper mills and reviewed the state of the art of this lignin stabilized soils as engineering materials. In addition, the potential focuses requiring further study to promote lignin stabilization technology were expected. The results showed that physicochemical properties of by-product lignin were mainly controlled by plant biomass and production technology, which should be clearly examined before field application. By-product lignin exhibited a satisfactory performance of improving engineering properties of both cohesive soils and noncohesive soils with respect to strength, erosion resistance, and durability. The precipitated cementing materials bonded particles and filled pores in the soil matrix, while their formation mechanism had not clearly explored yet. By-product lignin stabilized soils suffered from performance deterioration as exposed to moisture intrusion and wetting-drying cycle. The formed bonding among soil particles was essential in affecting the mechanical responses and durability of stabilized soils. The desirable construction procedure and protective measure were encouraged to be established for safety applications of the stabilized soils. Additional researches were recommended to by-product lignin optimization/modification, dynamic behaviors of stabilized soils, and application in some special soils. The outcomes of this review are invaluable in facilitating application of biomass by-product lignin for stabilizing problematic soils in engineering constructions.
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•Chemical properties of by-product lignin depend on the source of biomass and production process.•Stabilization mechanism of lignin is different from that of calcium-based chemicals.•Long-term durability and protective measures are essential to the field application.•Lignin modification is a promising way to reinforce its application as sustainable geomaterials.
Enhancing endocannabinoid signaling produces anxiolytic- and antidepressant-like effects, but the neural circuits involved remain poorly understood. The medial habenula (MHb) is a ...phylogenetically-conserved epithalamic structure that is a powerful modulator of anxiety- and depressive-like behavior. Here, we show that a robust endocannabinoid signaling system modulates synaptic transmission between the MHb and its sole identified GABA input, the medial septum and nucleus of the diagonal band (MSDB). With RNAscope in situ hybridization, we demonstrate that key enzymes that synthesize or degrade the endocannabinoids 2-arachidonylglycerol (2-AG) or anandamide are expressed in the MHb and MSDB, and that cannabinoid receptor 1 (CB1) is expressed in the MSDB. Electrophysiological recordings in MHb neurons revealed that endogenously-released 2-AG retrogradely depresses GABA input from the MSDB. This endocannabinoid-mediated depolarization-induced suppression of inhibition (DSI) was limited by monoacylglycerol lipase (MAGL) but not by fatty acid amide hydrolase. Anatomic and optogenetic circuit mapping indicated that MSDB GABA neurons monosynaptically project to cholinergic neurons of the ventral MHb. To test the behavioral significance of this MSDB-MHb endocannabinoid signaling, we induced MSDB-specific knockout of CB1 or MAGL via injection of virally-delivered Cre recombinase into the MSDB of Cnr1
or Mgll
mice. Relative to control mice, MSDB-specific knockout of CB1 or MAGL bidirectionally modulated 2-AG signaling in the ventral MHb and led to opposing effects on anxiety- and depressive-like behavior. Thus, depression of synaptic GABA release in the MSDB-ventral MHb pathway may represent a potential mechanism whereby endocannabinoids exert anxiolytic and antidepressant-like effects.
Alzheimer's disease (AD) is the most common type of neurodegenerative disease in the contemporary era, and it is still clinically incurable. Eriodictyol, a natural flavonoid compound that is mainly ...present in citrus fruits and some Chinese herbal medicines, has been reported to exert anti-inflammatory, antioxidant, anticancer and neuroprotective effects. However, few studies have examined the anti-AD effect and molecular mechanism of eriodictyol.
APP/PS1 mice were treated with eriodictyol and the cognitive function of mice was assessed using behavioral tests. The level of amyloid-β (Aβ) aggregation and hyperphosphorylation of Tau in the mouse brain were detected by preforming a histological analysis and Western blotting. HT-22 cells induced by amyloid-β peptide (1-42) (Aβ
) oligomers were treated with eriodictyol, after which cell viability was determined and the production of p-Tau was tested using Western blotting. Then, the characteristics of ferroptosis, including iron aggregation, lipid peroxidation and the expression of glutathione peroxidase type 4 (GPX4), were determined both in vivo and in vitro using Fe straining, Western blotting and qPCR assays. Additionally, the expression level of vitamin D receptor (VDR) and the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway were tested using Western blotting and qPCR assays. Afterward, HT-22 cells with VDR knockout were used to explore the potential mechanisms, and the relationship between VDR and Nrf2 was further assessed by performing a coimmunoprecipitation assay and bioinformatics analysis.
Eriodictyol obviously ameliorated cognitive deficits in APP/PS1 mice, and suppressed Aβ aggregation and Tau phosphorylation in the brains of APP/PS1 mice. Moreover, eriodictyol inhibited Tau hyperphosphorylation and neurotoxicity in HT-22 cells induced by Aβ
oligomer. Furthermore, eriodictyol exerted an antiferroptosis effect both in vivo and in vitro, and its mechanism may be associated with the activation of the Nrf2/HO-1 signaling pathway. Additionally, further experiments explained that the activation of Nrf2/HO-1 signaling pathway by eriodictyol treatment mediated by VDR.
Eriodictyol alleviated memory impairment and AD-like pathological changes by activating the Nrf2/HO-1 signaling pathway through a mechanism mediated by VDR, which provides a new possibility for the treatment of AD.
Link Between m6A Modification and Cancers Liu, Zhen-Xian; Li, Li-Man; Sun, Hui-Lung ...
Frontiers in bioengineering and biotechnology,
07/2018, Volume:
6
Journal Article
Peer reviewed
Open access
N6-methyladenosine (m6A) epitranscriptional modification has recently gained much attention. Through the development of m6A sequencing, the molecular mechanism and importance of m6A have been ...revealed. m6A is the most abundant internal modification in higher eukaryotic mRNAs, which plays crucial roles in mRNA metabolism and multiple biological processes. In this review, we introduce the characteristics of m6A regulators, including "writers" that create m6A mark, "erasers" that show demethylation activity and "readers" that decode m6A modification to govern the fate of modified transcripts. Moreover, we highlight the roles of m6A modification in several common cancers, including solid and non-solid tumors. The regulators of m6A exert enormous functions in cancer development, such as proliferation, migration and invasion. Especially, with the underlying mechanisms being uncovered, m6A and its regulators are expected to be the targets for the diagnosis and treatment of cancers.
Rh(III)-catalyzed C–H activation assisted by an oxidizing directing group has evolved to a mild and redox-economic strategy for the construction of heterocycles. Despite the success, these coupling ...systems are currently limited to cleavage of an oxidizing N–O or N–N bond. Cleavage of an oxidizing C–N bond, which allows for complementary carbocycle synthesis, is unprecedented. In this article, α-ammonium acetophenones with an oxidizing C–N bond have been designed as substrates for Rh(III)-catalyzed C–H activation under redox-neutral conditions. The coupling with α-diazo esters afforded benzocyclopentanones, and the coupling with unactivated alkenes such as styrenes and aliphatic olefins gave ortho-olefinated acetophenoes. In both systems the reactions proceeded with a broad scope, high efficiency, and functional group tolerance. Moreover, efficient one-pot coupling of diazo esters has been realized starting from α-bromoacetophenones and triethylamine. The reaction mechanism for the coupling with diazo esters has been studied by a combination of experimental and theoretical methods. In particular, three distinct mechanistic pathways have been scrutinized by DFT studies, which revealed that the C–H activation occurs via a C-bound enolate-assisted concerted metalation–deprotonation mechanism and is rate-limiting. In subsequent C–C formation steps, the lowest energy pathway involves two rhodium carbene species as key intermediates.
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