Abstract
The demand for sustainable energy has motivated the development of artificial photosynthesis. Yet the catalyst and reaction interface designs for directly fixing permanent gases (e.g. CO
2
, ...O
2
, N
2
) into liquid fuels are still challenged by slow mass transfer and sluggish catalytic kinetics at the gas-liquid-solid boundary. Here, we report that gas-permeable metal-organic framework (MOF) membranes can modify the electronic structures and catalytic properties of metal single-atoms (SAs) to promote the diffusion, activation, and reduction of gas molecules (e.g. CO
2,
O
2
) and produce liquid fuels under visible light and mild conditions. With Ir SAs as active centers, the defect-engineered MOF (e.g. activated NH
2
-UiO-66) particles can reduce CO
2
to HCOOH with an apparent quantum efficiency (AQE) of 2.51% at 420 nm on the gas-liquid-solid reaction interface. With promoted gas diffusion at the porous gas-solid interfaces, the gas-permeable SA/MOF membranes can directly convert humid CO
2
gas into HCOOH with a near-unity selectivity and a significantly increased AQE of 15.76% at 420 nm. A similar strategy can be applied to the photocatalytic O
2
-to-H
2
O
2
conversions, suggesting the wide applicability of our catalyst and reaction interface designs.
To investigate the factors associated with the duration of severe acute respiratory syndrome coronavirus 2 RNA shedding in patients with coronavirus disease 2019 (COVID‐19). A retrospective cohort of ...COVID‐19 patients admitted to a designated hospital in Beijing was analyzed to study the factors affecting the duration of viral shedding. The median duration of viral shedding was 11 days (IQR, 8‐14.3 days) as measured from illness onset. Univariate regression analysis showed that disease severity, corticosteroid therapy, fever (temperature>38.5°C), and time from onset to hospitalization were associated with prolonged duration of viral shedding (P < .05). Multivariate regression analysis showed that fever (temperature>38.5°C) (OR, 5.1, 95%CI: 1.5‐18.1), corticosteroid therapy (OR, 6.3, 95%CI: 1.5‐27.8), and time from onset to hospitalization (OR, 1.8, 95%CI: 1.19‐2.7) were associated with increased odds of prolonged duration of viral shedding. Corticosteroid treatment, fever (temperature>38.5°C), and longer time from onset to hospitalization were associated with prolonged viral shedding in COVID‐19 patients.
Highlights
Corticosteroid treatment was associated with prolonged viral shedding in COVID‐19 patients
A wide area quantum key distribution (QKD) network deployed on communication infrastructures provided by China Mobile Ltd. is demonstrated. Three cities and two metropolitan area QKD networks were ...linked up to form the Hefei-Chaohu-Wuhu wide area QKD network with over 150 kilometers coverage area, in which Hefei metropolitan area QKD network was a typical full-mesh core network to offer all-to-all interconnections, and Wuhu metropolitan area QKD network was a representative quantum access network with point-to-multipoint configuration. The whole wide area QKD network ran for more than 5000 hours, from 21 December 2011 to 19 July 2012, and part of the network stopped until last December. To adapt to the complex and volatile field environment, the Faraday-Michelson QKD system with several stability measures was adopted when we designed QKD devices. Through standardized design of QKD devices, resolution of symmetry problem of QKD devices, and seamless switching in dynamic QKD network, we realized the effective integration between point-to-point QKD techniques and networking schemes.
Recently, the sulfate radical (SO4 • –) has been found to exhibit broad application prospects in various research fields such as chemical, biomedical, and environmental sciences. It has been ...suggested that SO4 • – could be transformed into a more reactive hydroxyl radical (•OH); however, no direct and unequivocal experimental evidence has been reported yet. In this study, using an electron spin resonance (ESR) secondary radical spin-trapping method coupled with the classic spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and the typical •OH-scavenging agent dimethyl sulfoxide (DMSO), we found that •OH can be produced from three SO4 • –-generating systems from weakly acidic (pH = 5.5) to alkaline conditions (optimal at pH = 13.0), while SO4 • – is the predominant radical species at pH < 5.5. A comparative study with three typical •OH-generating systems strongly supports the above conclusion. This is the first direct and unequivocal ESR spin-trapping evidence for •OH formation from SO4 • – over a wide pH range, which is of great significance to understand and study the mechanism of many SO4 • –-related reactions and processes. This study also provides an effective and direct method for unequivocally distinguishing •OH from SO4 • –.
Rosmarinic acid (RA) can elicit a neuroprotective effect against ischemic stroke, but the precise molecular mechanism remains poorly understood. In this study, an experimental ischemic stroke model ...was established in CD-1 mice (Beijing Vital River Laboratory Animal Technology, Beijing, China) by occluding the right middle cerebral artery for 1 hour and allowing reperfusion for 24 hours. After intraperitoneally injecting model mice with 10, 20, or 40 mg/kg RA, functional neurological deficits were evaluated using modified Longa scores. Subsequently, cerebral infarct volume was measured using TTC staining and ischemic brain tissue was examined for cell apoptosis with TUNEL staining. Superoxide dismutase activity and malondialdehyde levels were measured by spectrophometry. Expression of heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), Bcl-2, Bax, Akt, and phospho-Ser473 Akt proteins in ischemic brain tissue was detected by western blot, while mRNA levels of Nrf2, HO-1, Bcl-2, and Bax were analyzed using real time quantitative PCR. In addition, HO-1 enzyme activity was measured spectrophotometrically. RA (20 and 40 mg/kg) greatly improved neurological function, reduced infarct volume, decreased cell apoptosis, upregulated Bcl-2 protein and mRNA expression, downregulated Bax protein and mRNA expression, increased HO-1 and Nrf2 protein and mRNA expression, increased superoxide dismutase activity, and decreased malondialdehyde levels in ischemic brain tissue of model mice. However, intraperitoneal injection of a HO-1 inhibitor (10 mg/kg zinc protoporphyrin IX) reversed the neuroprotective effects of RA on HO-1 enzyme activity and Bcl-2 and Bax protein expression. The PI3K/Akt signaling pathway inhibitor LY294002 (10 mM) inhibited Akt phosphorylation, as well as Nrf2 and HO-1 expression. Our findings suggest that RA has anti-oxidative and anti-apoptotic properties that protect against ischemic stroke by a mechanism involving upregulation of Nrf2 and HO-1 expression via the PI3K/Akt signaling pathway.
Aiming to improve the rate capability and cycling stability, cesium doped Li-rich cathode materials Li1.2-xCsxNi0.13Co0.13Mn0.54O2 (x = 0, 0.012, 0.036, 0.060, 0.096) are synthesized by a sol-gel ...method and a subsequent calcination process. The optimal Cs+ content is found to be x = 0.060. After Cesium doping to Li+ sites, the enlarged interplanar spacing of (003) plane, which is confirmed by high resolution transmission electron microscopy, can accelerate the Li+ diffusion during the lithiation/delithiation process at the interface of electrode/electrolyte. The obtained Cs-doped Li-rich sample with x = 0.060 exhibits much improved electrochemical performance compared with the bare, especially the rate capability (148 mAh g−1 compared to 50 mAh g−1 at 10 C). The first discharge capacity is much enhanced from 250 to 281 mAh g−1 at 0.1 C with a heightened coulombic efficiency from 72% to 81%. XRD, SEM, TEM, elemental mapping, EDS and ICP-AES are adopted to characterize the morphologies and structures.
•Cesium is successfully doped to Li+ sites in Li-rich cathode material.•Both rate and cycling properties are enhanced for Li1.14Cs0.06Ni0.13Co0.13Mn0.54O2.•A variety of techniques are adopted to elucidate the improvement mechanism.
•Distribution of liquid film outside the elliptical and circular tube is simulated.•The thickness of liquid film obtained from simulation and experiment agrees well.•The effects of key parameters on ...the heat transfer coefficient were investigated.•The heat transfer coefficient of evaporator with elliptical tubes is clarified.•The results are useful to design the falling-film evaporator with elliptical tube.
The falling film evaporation outside the elliptical tube was studied and compared with the circular tube for the design and improvement of seawater desalination system using the method of theoretical analysis, CFD numerical simulation and experiments. The experiment shows that the thickness of liquid film outside elliptical tube of E (ellipticity)=1.5 obtained from the simulation agrees well with the experimental data and the maximum deviation is within 8%. This fully illustrates that the numerical model is correct and that analog calculation is feasible. The experimental results also manifested that heat transfer coefficient of the system with E=1.5 elliptical tubes increases by 20–22% compared with circular tubes. This study testified that it is superiority and feasibility that elliptical tubes were applied to falling-film evaporation and seawater desalination of horizontal tubes. The exploratory researches will be conducted for promoting the design and application of falling film evaporation with elliptical tubes in the seawater desalination system.
To study the feasibility of use of radiomic features extracted from axillary lymph nodes for diagnosis of their metastatic status in patients with breast cancer.
A total of 176 axillary lymph nodes ...of patients with breast cancer, consisting of 87 metastatic axillary lymph nodes (ALNM) and 89 negative axillary lymph nodes proven by surgery, were retrospectively reviewed from the database of our cancer center. For each selected axillary lymph node, 106 radiomic features based on preoperative pharmacokinetic modeling dynamic contrast enhanced magnetic resonance imaging (PK-DCE-MRI) and 5 conventional image features were obtained. The least absolute shrinkage and selection operator (LASSO) regression was used to select useful radiomic features. Logistic regression was used to develop diagnostic models for ALNM. Delong test was used to compare the diagnostic performance of different models.
The 106 radiomic features were reduced to 4 ALNM diagnosis-related features by LASSO. Four diagnostic models including conventional model, pharmacokinetic model, radiomic model, and a combined model (integrating the Rad-score in the radiomic model with the conventional image features) were developed and validated. Delong test showed that the combined model had the best diagnostic performance: area under the curve (AUC), 0.972 (95% CI 0.947-0.997) in the training cohort and 0.979 (95% CI 0.952-1) in the validation cohort. The diagnostic performance of the combined model and the radiomic model were better than that of pharmacokinetic model and conventional model (P<0.05).
Radiomic features extracted from PK-DCE-MRI images of axillary lymph nodes showed promising application for diagnosis of ALNM in patients with breast cancer.
Polyhaloaromatic compounds (XAr) are ubiquitous and recalcitrant in the environment. They are potentially carcinogenic to organisms and may induce serious risks to the ecosystem, raising increasing ...public concern. Therefore, it is important to detect and quantify these ubiquitous XAr in the environment, and to monitor their degradation kinetics during the treatment of these recalcitrant pollutants. We have previously found that unprecedented intrinsic chemiluminescence (CL) can be produced by a haloquinones/H2O2 system, a newly-found ●OH-generating system different from the classic Fenton system. Recently, we found that the degradation of priority pollutant pentachlorophenol by the classic Fe(II)-Fenton system could produce intrinsic CL, which was mainly dependent on the generation of chloroquinone intermediates. Analogous effects were observed for all nineteen chlorophenols, other halophenols and several classes of XAr, and a novel, rapid and sensitive CL-based analytical method was developed to detect these XAr and monitor their degradation kinetics. Interestingly, for those XAr with halohydroxyl quinoid structure, a Co(II)-mediated Fenton-like system could induce a stronger CL emission and higher degradation, probably due to site-specific generation of highly-effective ●OH. These findings may have broad chemical and environmental implications for future studies, which would be helpful for developing new analytical methods and technologies to investigate those ubiquitous XAr.
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