Efficient and reversible separation of NH_(3) by deep eutectic solvents with multiple active sites and low viscosities

The efficient separation and collection of ammonia(NH_(3))during NH_(3) synthesis process is essential to improve the economic efficiency and protect the environment.In this work,ethanolammonium hydrochloride(EtOHACl)and phenol(PhOH)were used to prepare a novel class of deep eutectic solvents(DESs)with multiple active sites and low viscosities.The NH_(3) separation performance of EtOHACl+PhOH DESs was analyzed completely.It is figured out that the NH_(3) absorption rates in EtOHACl+PhOH DESs are very fast.The NH_(3) absorption capacities are very high and reach up to 5.52 and 10.74 mol·kg1 at 11.2 and 100.4 kPa under 298.2 K,respectively.In addition,the EtOHACl+PhOH DESs present highly selective absorption of NH_(3) over N_(2) and H_(2) and good regenerative properties after seven cycles of absorption/desorption.The intrinsic separation mechanism of NH_(3) by EtOHACl+PhOH DESs was further revealed by spectroscopic analysis and quantum chemistry calculations.

Electronic engineering of Co-Ru diatomic sites and Ru nanoparticles for synergistic promotion of hydrogen evolution

The coexistence of multi-component active sites like single-atom sites,diatomic sites(DAS)and nanoclusters is shown to result in superior performances in the hydrogen evolution reaction(HER).Metal diatomic sites are more complex than single-atom sites but their unique electronic structures can lead to significant enhancement of the HER kinetics.Although the synthesis and identification of DAS is usually challenging,we report a simple access to a diatomic catalyst by anchoring Co-Ru DAS on nitrogen-doped carbon supports along with Ru nanoparticles(NPs).Experimental and theoretical results revealed the atomic-level characteristics of Co-Ru sites,their strong electronic coupling and their synergy with Ru NPs within the catalyst.The unique electronic structure of the catalyst resulted in an excellent HER activity and stability in alkaline media.This work provides a valuable insight into a widely applicable design of diatomic catalysts with multi-component active sites for highly efficient HER electrocatalysis.

Trace determination and characterization of ginsenosides in rat plasma through magnetic dispersive solid-phase extraction based on core-shell polydopamine-coated magnetic nanoparticles

Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging.This study presented a one-pot synthesis of magnetic polydopamine nanoparticles(Fe3O4@-SiO2@PDA NPs)with multiple recognition sites for the magnetic dispersive solid-phase extraction(MDSPE)of ginsenosides from rat plasma treated with white ginseng.The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a highresolution mass spectrometry with supplemental UNIFI libraries.Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides.The reusability of Fe3O4@-SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80%after recycling 6 times.Furthermore,the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma.In comparison,conventional methanol method can only detect 8 ginsenosides from the same plasma samples.The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.

A prospective cohort study of the presence of SARS-CoV-2 in clinical samples from multiple bodily sites:implications for transmission routes of COVID-19

Objective: The coronavirus disease 2019 (COVID-19) epidemic resulting from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has still spread globally. The occurrence of the Delta variant, which is more infectious and spreads faster than earlier forms of the virus that causes COVID-19, makes infection prevention more challenging. Therefore, this study aimed to gain a comprehensive insight into the transmission routes of SARS-CoV-2 for curbing the propagation of SARS-CoV-2 in human populations.Methods: We studied a prospective cohort of 576 patients admitted consecutively to the First Affiliated Hospital of Guangzhou Medical University from January 21 to June 8, 2020. These patients were chosen based on their similar clinical phenotypes or imaging findings. There were 21 (3.6%) laboratory-confirmed COVID-19 patients (16 severe and 5 mild cases) and 555 non-COVID-19 patients. The antibody response and routes and duration of viral shedding were systematically evaluated in serial clinical specimens. Moreover, SARS-CoV-2 RNA was also detected in a mouth rinse, urine, and tear samples. This study was approved by the Medical Ethical Committee of The First Affiliated Hospital of Guangzhou Medical University (approval No. 2020-77).Results: SARS-CoV-2 mainly existed in sputum, nasal and throat swabs, and feces samples. Virus latency was longer in sputum and feces samples than in nasopharyngeal samples. IgG antibody response in respiratory samples was related to disease severity. Although droplets and aerosols are the major transmission routes for COVID-19, covert routes of transmission from asymptomatic patients, contaminated surfaces, and wastewater are also of interest.Conclusion: Our findings provide a solid foundation for developing prophylactic measures against SARS-CoV-2.

光催化CO_(2)还原多原子催化剂的设计与制备进展

光催化CO_(2)还原合成太阳能燃料对缓解CO_(2)排放引起的全球变暖和降低化石燃料消耗具有重要意义.然而,目前的光催化剂仍然存在反应动力学缓慢和选择性不理想的问题,特别是对于C_(2+)产物的生成,极大地限制了光催化的工业化进程.过去几十年中,关于太阳能驱动的CO_(2)还原的研究展示出鼓舞人心的结果,包括活性位点的构建.本综述重点介绍了通过构建活性位点制备原子级分散催化剂在光催化CO_(2)还原中的最新进展,包括两个独立的活性位点、成对双活性位点和基于活性位点构型的纳米团簇.此外,详细讨论了CO_(2)在活性位点上的活化机制和表征方法.特别是考虑到实验研究与实际应用之间的差距,整合实验和理论的结果,以实现潜在的结构-活性关系和高目标产物选择性发展.最后,概述了该领域存在的挑战,并展望了活性位点的合理设计和机理研究.

Ambient electrosynthesis of urea from carbon dioxide and nitrate over Mo_(2)C nanosheet

Electrocatalytic synthesis of urea through C-N bond formation,converting carbon dioxide(CO_(2))and ni-trate(NO_(3)^(-)),presents a promising,less energy-intensive alternative to industrial urea production process.In this communication,we report the application of Mo_(2)C nanosheets-decorated carbon sheets(Mo_(2)C/C)as a highly efficient electrocatalyst for facilitating C-N coupling in ambient urea electrosynthesis.In CO_(2)-saturated 0.2 mol/L Na_(2)SO_(4)solution containing 0.05 mol/L NO_(3)^(-),the Mo_(2)C/C catalyst achieves an impres-sive urea yield of 579.13μg h^(-1)mg^(-1)with high Faradaic efficiency of 44.80%at-0.5 V versus the reversible hydrogen electrode.Further theoretical calculations reveal that the multiple Mo active sites enhance the formation of^(∗)CO and^(∗)NH_(2)intermediates and facilitate their C-N coupling.This research propels the use of Mo_(2)C-based electrodes in electrocatalysis and accentuates the capabilities of binary metal-based catalysts in C-N coupling reactions.

Study of methods for evaluating the probability of multiple site damage occurrences

Two methods currently available for evaluating the probability of Multiple Site Damage(MSD)occurrence were studied in this paper.One of the methods is a probabilistic analysis approach based on the statistical theory and fatigue characteristics of each structural detail,and the other is an approach which defines the initial damage scenario by means of Monte-Carlo simulation,and multiple initial crack scenarios are randomly generated.A modified method based on the Monte-Carlo simulation was proposed in this paper,in which the random fluctuation of the stress was considered to give more accurate evaluation results.In the presented method,the probability of MSD occurrence in a structural element containing multiple details was calculated based on the Monte-Carlo simulation and the p-S-N curve of a single structural detail.Fatigue tests were accomplished using specimens containing 21-similar-details to obtain the fatigue life corresponding to MSD occurrence.Tests on single-detail specimens and static calibration tests were also conducted to get the basic fatigue properties of the material and the degree of stress fluctuation.The aforementioned three methods were compared and validated via the test results.The influence of the stress random fluctuation degree on the probability of MSD occurrence and influence of the distribution types on evaluating the MSD occurrence probability were discussed.

A multisite-binding fluorescent probe for simultaneous monitoring of mitochondrial homocysteine, cysteine and glutathione in live cells and zebrafish

Homocysteine(Hcy), cysteine(Cys) and glutathione(GSH) play crucial roles in redox homeostasis during mitochondria functions. Simultaneous differentiation and visualization of mitochondrial biothiols dynamics are significant for understanding cell metabolism and their related diseases. Herein, a multisitebinding fluorescent probe(MCP) was developed for simultaneous sensing of mitochondrial Cys, GSH and Hcy from three fluorescence channels for the first time. This novel probe exhibited rapid fluorescence turn-on, good water-solubility, high selectivity and large spectral separation for discriminating Cys, GSH and Hcy with 131-, 96-, 748-fold fluorescence increasement at 471, 520, 567 nm through different excitation wavelengths, respectively. Importantly, this probe was successfully applied to simultaneous monitoring of mitochondrial Cys, GSH, and Hcy in live cells and zebrafish from three fluorescence channels,promoting the understanding of the functions of Hcy, Cys and GSH.

A fatigue damage-cumulative model in peridynamics

While the present structural integrity evaluation method is based on the philosophy of assumed similitude, Fatigue and Damage Tolerance(F&DT) evaluations for next generation of air-vehicles require high-fidelity physical models within cyberspace. To serve the needs of F&DT evaluation in digital twin paradigm, a fatigue damage-cumulative model within peridynamic framework is proposed in this paper. Based on the concept of fatigue element block and damage accumulation law in form of Coffin-Manson relationship, the proposed model applies to both fatigue crack initiation and fatigue crack growth;fatigue crack growth rates under constant-amplitude and simple variable-amplitude block loading cases can be well predicted for three common structural materials without inputs of Paris law parameters. Additionally, the proposed model can also be easily extended to a probabilistic version;for verification, multiple-site-damage problems are simulated and the statistic nature of fatigue process in experiments can be well captured. In the end, main features of the proposed model are summarized, and distinctions from the other models are discussed. There may be a potential for the peridynamic damage-cumulative model proposed in this work to numerically predict fatigue problems in digital twin paradigm for future generations of aerospace vehicles.