Co‐based spinel oxides, which are of mixing valences with the presence of both Co2+ and Co3+ at different atom locations, are considered as promising catalysts for the electrochemical oxidation of ...5‐hydroxymethylfurfural (HMF). Identifying the role of each atom site in the electroxidation of HMF is critical to design the advanced electrocatalysts. In this work, we found that Co2+Td in Co3O4 is capable of chemical adsorption for acidic organic molecules, and Co3+Oh play a decisive role in HMF oxidation. Thereafter, the Cu2+ was introduced in spinel oxides to enhance the exposure degree of Co3+ and to boost acidic adsorption and thus to enhance the electrocatalytic activity for HMF electrooxidation significantly.
The exploration of optimal geometrical site in Co3O4 for electrochemical HMF oxidation by the building tetrahedral (Zn2+) and octahedral (Al3+) blocks is described. The electrochemical results demonstrate that Co3+Oh are the best geometrical sites for HMF oxidation, and the chemical adsorption for acidic organic molecules is dominated by Co2+Td. The exposure degree of Co3+ is improved by Cu2+ and thus results in a record activity.
The selective hydrogenation of acetylene to ethylene in an ethylene‐rich gas stream is an important process in the chemical industry. Pd‐based catalysts are widely used in this reaction due to their ...excellent hydrogenation activity, though their selectivity for acetylene hydrogenation and durability need improvement. Herein, the successful synthesis of atomically dispersed Pd single‐atom catalysts on nitrogen‐doped graphene (Pd1/N‐graphene) by a freeze‐drying‐assisted method is reported. The Pd1/N‐graphene catalyst exhibits outstanding activity and selectivity for the hydrogenation of C2H2 with H2 in the presence of excess C2H4 under photothermal heating (UV and visible‐light irradiation from a Xe lamp), achieving 99% conversion of acetylene and 93.5% selectivity to ethylene at 125 °C. This remarkable catalytic performance is attributed to the high concentration of Pd active sites on the catalyst surface and the weak adsorption energy of ethylene on isolated Pd atoms, which prevents C2H4 hydrogenation. Importantly, the Pd1/N‐graphene catalyst exhibits excellent durability at the optimal reaction temperature of 125 °C, which is explained by the strong local coordination of Pd atoms by nitrogen atoms, which suppresses the Pd aggregation. The results presented here encourage the wider pursuit of solar‐driven photothermal catalyst systems based on single‐atom active sites for selective hydrogenation reactions.
Pd single‐atom catalysts on nitrogen‐doped graphene are successfully fabricated. A Pd1/N‐graphene catalyst (Pd loading of 2.3 wt%) exhibits outstanding activity and selectivity for the selective hydrogenation of acetylene in the presence of excess ethylene under photothermal or direct thermal heating at 125 °C, which is attributed to the suppression of C2H4 hydrogenation to C2H6 by Pd‐N4 surface sites.
Producing indispensable hydrogen and oxygen for social development via water electrolysis shows more prospects than other technologies. Although electrocatalysts have been explored for centuries, a ...universal activity descriptor for both hydrogen‐evolution reaction (HER) and oxygen‐evolution reaction (OER) is not yet developed. Moreover, a unifying concept is not yet established to simultaneously understand HER/OER mechanisms. Here, the relationships between HER/OER activities in three common electrolytes and over ten representative material properties on 12 3d‐metal‐based model oxides are rationally bridged through statistical methodologies. The orbital charge‐transfer energy (Δ) can serve as an ideal universal descriptor, where a neither too large nor too small Δ (≈1 eV) with optimal electron‐cloud density around Fermi level affords the best activities, fulfilling Sabatier's principle. Systematic experiments and computations unravel that pristine oxide with Δ ≈ 1 eV possesses metal‐like high‐valence configurations and active lattice‐oxygen sites to help adsorb key protons in HER and induce lattice‐oxygen participation in the OER, respectively. After reactions, partially generated metals in the HER and high‐valence hydroxides in the OER dominate proton adsorption and couple with pristine lattice‐oxygen activation, respectively. These can be successfully rationalized by the unifying orbital charge‐transfer theory. This work provides the foundation of rational material design and mechanism understanding for many potential applications.
A universal activity descriptor (orbital charge‐transfer energy) is successfully extracted from various materials’ physicochemical properties for both hydrogen‐evolving and oxygen‐evolving reactions in multiple electrolytes. Systematic experiments and computations reveal the life‐cycle HER and OER mechanisms and identify the unifying orbital charge‐transfer theory as a powerful mechanism analysis tool and foundation.
The nucleophile oxidation reaction (NOR) is of enormous significance for organic electrosynthesis and coupling for hydrogen generation. However, the nonuniform NOR mechanism limits its development. ...For the NOR, involving electrocatalysis and organic chemistry, both the electrochemical step and non‐electrochemical process should be taken into account. The NOR of nickel‐based hydroxides includes the electrogenerated dehydrogenation of the Ni2+–OH bond and a spontaneous non‐electrochemical process; the former determines the electrochemical activity, and the nucleophile oxidation pathway depends on the latter. Herein, the space‐confinement‐induced synthesis of Ni3Fe layered double hydroxide intercalated with single‐atom‐layer Pt nanosheets (Ni3Fe LDH‐Pt NS) is reported. The synergy of interlayer Pt nanosheets and multiple defects activates Ni–OH bonds, thus exhibiting an excellent NOR performance. The spontaneous non‐electrochemical steps of the NOR are revealed, such as proton‐coupled electron transfer (PCET; Ni3+–O + X–H = Ni2+–OH + X•), hydration, and rearrangement. Hence, the reaction pathway of the NOR is deciphered, which not only helps to perfect the NOR mechanism, but also provides inspiration for organic electrosynthesis.
The nucleophile oxidation reaction (NOR) is a complex reaction including electrochemical step and spontaneous non‐electrochemical process. The interlayer Pt nanosheets and multiple defects of Ni3Fe LDH‐Pt NS enable the activated Ni2+–OH to exhibit an excellent NOR activity. More importantly, spontaneous non‐electrochemical steps, including proton‐coupled electron transfer, hydration, and rearrangement, lead to diverse nucleophile dehydrogenation oxidation pathways of different NOR systems.
Identification of novel biomarkers is needed to improve the diagnosis and prognosis of heart failure (HF). Metabolic disturbance is remarkable in patients with HF.
This study sought to assess the ...diagnostic and prognostic values of metabolomics in HF.
Mass spectrometry-based profiling of plasma metabolites was performed in 515 participants; the discovery phase study enrolled 51 normal control subjects and 183 HF patients, and the validation study enrolled 63 control subjects and 218 patients with stage C HF. Another independent group of 32 patients with stage C HF who recovered to New York Heart Association functional class I at 6 and 12 months was profiled as the "recovery" group.
A panel of metabolites, including histidine, phenylalanine, spermidine, and phosphatidylcholine C34:4, has a diagnostic value similar to B-type natriuretic peptide (BNP). In the recovery group, the values of this panel significantly improved at 6 and 12 months. To evaluate the prognostic values, events were defined as the combined endpoints of death or HF-related re-hospitalization. A metabolite panel, which consisted of the asymmetric methylarginine/arginine ratio, butyrylcarnitine, spermidine, and the total amount of essential amino acids, provided significant prognostic values (p < 0.0001) independent of BNP and traditional risk factors. The prognostic value of the metabolite panel was better than that of BNP (area under the curve of 0.85 vs. 0.74 for BNP) and Kaplan-Meier curves (log rank: 17.5 vs. 9.95). These findings were corroborated in the validation study.
Metabolomics demonstrate powerful diagnostic value in estimating HF-related metabolic disturbance. The profile of metabolites provides better prognostic value versus conventional biomarkers.
Copper-ceria is one of the very active catalysts for the preferential oxidation of carbon monoxide (CO-PROX) reaction, which is also a typical system in which the complexity of copper chemistry is ...clearly exhibited. In the present manuscript, copper–ceria catalysts with different Cu contents up to 20 wt % supported on CeO2 nanorods were synthesized by a deposition–precipitation (DP) method. The as-prepared samples were characterized by various structural and textural detections including X-ray diffraction (XRD), Vis-Raman, transmission electron microscopy (TEM), ex situ/in situ X-ray absorption fine structure (XAFS), and temperature-programmed reduction by hydrogen (H2-TPR). It has been confirmed that the highly dispersed copper oxide (CuO x ) clusters, as well as the strong interaction of Cu-O x -Ce structure, were the main copper species deposited onto the ceria surface. No separated copper phase was detected for both preoxidized and prereduced samples with the Cu contents up to 10 wt %. The fresh copper–ceria catalysts were pretreated in either O2- or H2-atmosphere and then tested for the CO-PROX reaction at a space velocity (SV) of 60 000 mL·h–1·gcat –1. The prereduced 5 and 10 wt % Cu samples exhibited excellent catalytic performance with high CO conversions (>50%, up to 100%) and O2 selectivities (>60%, up to 100%) within a wide temperature window of 80–140 °C. The in situ XAFS technique was carried out to monitor the structural evolution on the copper–ceria catalysts during the PROX experiments. The X-ray absorption near edge spectra (XANES) profiles, by the aid of linear combination analysis, identified the oxidized Cu(II) were the dominant copper species in both O2- and H2-pretreated samples after CO-PROX at 80 °C. Furthermore, the extended X-ray absorption fine structure (EXAFS) fitting results, together with the corresponding H2-TPR data distinctly determined that the highly dispersed CuO x (x = 0.2−0.5) cluster, other than the Cu–O x –Ce (x = 0.7−3.2) structure, were the crucial active species for the studied CO-PROX reaction.
Stroke, characterized as a neurological deficit of cerebrovascular cause, is very common in older adults. Increasing evidence suggests stroke contributes to the risk and severity of cognitive ...impairment. People with cognitive impairment following stroke often face with quality-of-life issues and require ongoing support, which have a profound effect on caregivers and society. The high morbidity of post-stroke cognitive impairment (PSCI) demands effective management strategies, in which preventive strategies are more appealing, especially those targeting towards modifiable risk factors. In this review article, we attempt to summarize existing evidence and knowledge gaps on PSCI: elaborating on the heterogeneity in current definitions, reporting the inconsistent findings in PSCI prevalence in the literature, exploring established or less established predictors, outlining prevention and treatment strategies potentially effective or currently being tested, and proposing promising directions for future research.
Abstract
To assess plasma phosphorylated tau181 (p-tau181) as a progression biomarker in Alzheimer’s disease (AD), we examined longitudinal plasma p-tau181 of 1184 participants (403 cognitively ...normal (CN), 560 patients with mild cognitive impairment (MCI), and 221 with AD dementia) from Alzheimer’s Disease Neuroimaging Initiative (ADNI). The plasma p-tau level was increased at baseline for MCI and AD dementia (mean: CN, 15.4 pg/mL; MCI, 18.4 pg/mL; AD dementia, 23.7 pg/mL;
P
< 0.001) and increased significantly over time at preclinical (Aβ-positive CN), prodromal (Aβ-positive MCI), and dementia (Aβ-positive dementia) stage of AD. A longitudinal increase of plasma p-tau181 was associated with abnormal cerebrospinal fluid biomarker levels (low Aβ42, high phosphorylated tau, and high total tau, all
P
< 0.001), amyloid accumulation (
P
< 0.001) and hypometabolism (
P
= 0.002) on positron emission tomography, atrophy in structure imaging (small hippocampal (
P
= 0.030), middle temporal (
P
= 0.008), and whole brain (
P
= 0.027) volume, and large ventricular volume (
P
= 0.008)), and deteriorated cognitive performance (global cognition and memory, language, executive function, and visuospatial function, all
P
< 0.050) at baseline. Furthermore, longitudinal plasma p-tau181 correlated with concurrent changes of nearly all these AD-related hallmarks and faster increase in plasma p-tau181 correlated with faster worsening cognition in all diagnostic groups. Importantly, most associations remained significant in Aβ-positive group and became non-significant in Aβ-negative group. Longitudinal analyses of plasma p-tau181 suggest its potential as a noninvasive biomarker to track disease progression in AD and to monitor effects of disease-modifying therapeutics in clinical trials.
Electrochemical CO2 reduction reaction (ECO2RR) with controlled product selectivity is realized on Ag−Cu bimetallic surface alloys, with high selectivity towards C2 hydrocarbons/alcohols (≈60 % ...faradaic efficiency, FE), C1 hydrocarbons/alcohols (≈41 % FE) and CO (≈74 % FE) achieved by tuning surface compositions and applied potentials. In situ spectral investigations and theoretical calculations reveal that surface‐composition‐dependent d‐band center could tune *CO binding strengths, regulating the *CO subsequent reaction pathways and then the product selectivity. Further adjusting the applied potentials will alter the energy of participated electrons, which leads to controlled ECO2RR selectivity towards desired products. A predominant region map, with an indicator proposed to evaluate the thermodynamic predominance of the *CO subsequent reactions, is then provided as a reliable theoretical guidance for the controllable ECO2RR product selectivity over bimetallic alloys.
Ag−Cu surface alloys, as electrocatalysts for CO2 reduction, demonstrated controllable product selectivity when their surface compositions and the applied potentials were rationally tuned. The working mechanism of these catalysts was revealed by in situ spectral investigations and theoretical calculations. A predominant region map describing the thermodynamic predominance of *CO involved subsequent reactions is provided as reliable guidance for the design of catalysts for CO2 reduction towards value‐added products.
Differentiation of bone marrow derived mesenchymal stem cells (BMSCs) into functional neural cells has been widely investigated for treating neural diseases. However, the limited neural ...differentiation of BMSCs remains a big challenge to overcome. Herein, for the first time, ginseng-derived exosomes (G-Exos) were demonstrated to have excellent efficiency in stimulating the neural differentiation of BMSCs by transferring the incorporated miRNAs to BMSCs efficiently. In vivo, a photo-cross-linkable hydrogel with chemokine and G-Exos loaded shows strong efficacy in recruiting and directing the neural differentiation of BMSCs in the program. G-Exos were demonstrated to be promising nanoplatforms in transferring plant-derived miRNAs to mammalian stem cells for neural differentiation both in vitro and in vivo, possessing great potential in neural regenerative medicine.
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