► Chemical stability of lithium polysulfide greatly affects Li/S cell's cycling performance. ► Quaternary ammonium stabilizes polysulfide and increases Li/S cell's capacity retention. ► LiNO3 ...effectively suppresses redox shuttle and increases Li/S cell's charging efficiency. ► LiNO3 is gradually consumed and its improvement is eventually vanished with cycling.
The lithium/sulfur (Li/S) cell is a liquid electrochemical system, in which the dissolution of lithium polysulfide (PS, the series of the sulfur reduction intermediates) plays an essential role in the cell's performance. In solution, the PS undergo a series of complicated disproportionations, as described by a general equation of Li2Sn→m/8S8+Li2Sn−m, to form the less soluble sulfur and low-order PS, which become inactive once precipitated out of the liquid electrolyte or deposited into the pores of separator. Based on the hard and soft acids and bases (HSAB) theory, quaternary ammonium cations are expected to stabilize the PS anions through a chemical interaction between the soft acid and soft base. In this paper, we report a significant improvement in the capacity retention of a Li/S cell by introducing a tetrabutylammonium triflate (NBu4SO3CF3) or an N-methyl-N-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) into the liquid electrolyte. For example, by using an electrolyte of 0.25molkg−1 LiNO3–0.25molkg−1 PYR14TFSI dissolved in a 1:1 (wt.) mixture of dimethyl ether (DME) and 1,3-dioxolane (DOL), a Li/S cell with a cathode containing 77% sulfur and a 2mgcm−2 sulfur loading exhibited an initial capacity of 1227mAhg−1 and retained a capacity of 875mAhg−1 after 40 cycles when cycled at 0.2mAcm−2 between 1.7V and 2.8V. We contribute the improved performance to the stabilized PS anions by the added quaternary ammonium cations.
Abstract
A novel coronavirus (COVID-19) pandemic threatens the world. Here, we first studied the dynamics profile of SARS-CoV-2 from 56 recovered patients with COVID-19. We found viral shedding ...occurred up to 6 weeks after onset of symptoms. A prolonged observation period is necessary for older patients.
Pre-lithiation is an indispensable step for making hybrid lithium-ion capacitors (LICs), its high cost and process complexity have greatly hindered the commercialization of LICs. Aiming to eliminate ...the pre-lithiation step, we propose an in-situ lithiation concept by introducing a Li+ ion source material into the positive electrode to enable the lithiation to be completed in the formation cycle. In this paper we start with the fundamental principle of LICs to discuss the requirements for Li+ ion source materials and demonstrate this concept by employing Li-rich Li2CuO2 as the Li+ ion source material, natural graphite and activated carbon (AC) as the negative and positive electrode materials. It is shown that the LICs made such behave as a pure capacitor with ability to deliver the same level of specific capacity and specific capacitance, i.e., 56 mAh g−1 and 143 F g−1 vs. the mass of AC in the voltage range between 2.8 V and 4.2 V, as those obtained from the counterpart Li/AC half-cell. The present concept is also applicable to other LICs with the negative electrode required to be pre-lithiated.
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•Discussed the superiority of hybrid LIC to symmetric EDLC in view of working principle.•Eliminated pre-lithiation step for making of LICs by using a Li+ ion source material.•Discussed requirements for the Li+ ion source materials.•Demonstrated a proof-of-concept LIC using Li2CuO2 as the Li+ ion source material.
Exhaustion of cytotoxic effector natural killer (NK) and CD8
T cells have important functions in the establishment of persistent viral infections, but how exhaustion is induced during chronic ...hepatitis C virus (HCV) infection remains poorly defined. Here we show, using the humanized C/O
mice permissive for persistent HCV infection, that NK and CD8
T cells become sequentially exhausted shortly after their transient hepatic infiltration and activation in acute HCV infection. HCV infection upregulates Qa-1 expression in hepatocytes, which ligates NKG2A to induce NK cell exhaustion. Antibodies targeting NKG2A or Qa-1 prevents NK exhaustion and promotes NK-dependent HCV clearance. Moreover, reactivated NK cells provide sufficient IFN-γ that helps rejuvenate polyclonal HCV CD8
T cell response and clearance of HCV. Our data thus show that NKG2A serves as a critical checkpoint for HCV-induced NK exhaustion, and that NKG2A blockade sequentially boosts interdependent NK and CD8
T cell functions to prevent persistent HCV infection.
Amino acids act as versatile nutrients driving cell growth and survival, especially in cancer cells. Amino acid metabolism comprises numerous metabolic networks and is closely linked with ...intracellular redox balance and epigenetic regulation. Reprogrammed amino acid metabolism has been recognized as a ubiquitous feature in tumour cells. This review outlines the metabolism of several primary amino acids in cancer cells and highlights the pivotal role of amino acid metabolism in sustaining redox homeostasis and regulating epigenetic modification in response to oxidative and genetic stress in cancer cells.
The interlink between amino acid metabolism and epigenetic regulation. Epigenetic methylation and acetylation might be regulated by amino acid metabolism.
Long charging time for Li‐ion batteries is a critical obstacle for the widespread adoption of electric vehicles, especially when compared with the rapid refueling of traditional internal combustion ...engine vehicles. Fast charging results in accelerated performance degradation and low energy efficiency for Li‐ion batteries. The batteries adopted in the present electric vehicle market are mainly based on chemistry consisting of a graphite anode and a layered lithium transition‐metal oxide cathode. The fast‐charging capability of such batteries is limited by Li plating on the graphite anode and structural instability of the layered lithium transition‐metal oxide cathode. In this Minireview, the challenges and possible solutions to these fast charge problems are reviewed at both the materials and cell levels.
Getting in the fast lane? Fast charging results in accelerated performance degradation and low energy efficiency, which is primarily attributed to Li plating on graphite anodes, structural instability of the layered cathode materials, and electrolyte depletion. Mechanisms and possible solutions to the fast charging problems of Li‐ion batteries are critically reviewed.
Little is known about the changes in soil microbial phosphorus (P) cycling potential during terrestrial ecosystem management and restoration, although much research aims to enhance soil P cycling. ...Here, we used metagenomic sequencing to analyse 18 soil microbial communities at a P-deficient degraded mine site in southern China where ecological restoration was implemented using two soil ameliorants and eight plant species. Our results show that the relative abundances of key genes governing soil microbial P-cycling potential were higher at the restored site than at the unrestored site, indicating enhancement of soil P cycling following restoration. The gcd gene, encoding an enzyme that mediates inorganic P solubilization, was predominant across soil samples and was a major determinant of bioavailable soil P. We reconstructed 39 near-complete bacterial genomes harboring gcd, which represented diverse novel phosphate-solubilizing microbial taxa. Strong correlations were found between the relative abundance of these genomes and bioavailable soil P, suggesting their contributions to the enhancement of soil P cycling. Moreover, 84 mobile genetic elements were detected in the scaffolds containing gcd in the 39 genomes, providing evidence for the role of phage-related horizontal gene transfer in assisting soil microbes to acquire new metabolic potential related to P cycling.
Promoting Internet development and eliminating energy poverty are two important policy agendas for China in the era of digital economy. In the context of “Internet + energy”, there is a need to ...explore whether the development of the Internet can alleviate energy poverty. The aim of this study is to test the influence and transmission mechanism of the development of Internet on energy poverty in China by using provincial panel data from 2011 to 2019. The study found that: (1) energy poverty is still widespread in China, especially in the central and western regions. And the low energy affordability is its major source; (2) the development of Internet can alleviate energy poverty. On one hand, it can improve energy affordability by promoting economic development and technological progress. On the other hand, it also helps to enhance the availability of energy by promoting technological advances and improving knowledge level; and (3) there are nonlinear and regional heterogeneous effects of the development of Internet on the alleviation of energy poverty. Based on the above results, corresponding policy suggestions for China to alleviate energy poverty are provided.
•An energy poverty index was constructed for measuring the state of China's energy poverty.•Energy poverty is further decomposed into energy availability and energy affordability.•Currently, the major issue for China's energy poverty is its low energy affordability.•Internet development can alleviate China's energy poverty through a certain transmission mechanism.•There are nonlinear and regional heterogeneous effects of Internet development on energy poverty.
Objective
To assess the efficacy of intensive acupuncture (3 times weekly for 8 weeks) versus sham acupuncture for knee osteoarthritis (OA).
Methods
In this multicenter, randomized, sham‐controlled ...trial, patients with knee OA were randomly assigned to receive electroacupuncture (EA), manual acupuncture (MA), or sham acupuncture (SA) 3 times weekly for 8 weeks. Participants, outcome assessors, and statisticians were blinded with regard to treatment group assignment. The primary outcome measure was response rate, which is the proportion of participants who simultaneously achieved minimal clinically important improvement in pain and function by week 8. The primary analysis was conducted using a Z test for proportions in the modified intent‐to‐treat population, which included all randomized participants who had ≥1 post‐baseline measurement.
Results
Of the 480 participants recruited in the trial, 442 were evaluated for efficacy. The response rates at week 8 were 60.3% (91 of 151), 58.6% (85 of 145), and 47.3% (69 of 146) in the EA, MA, and SA groups, respectively. The between‐group differences were 13.0% (97.5% confidence interval 97.5% CI 0.2%, 25.9%; P = 0.0234) for EA versus SA and 11.3% (97.5% CI −1.6%, 24.4%; P = 0.0507) for MA versus SA. The response rates in the EA and MA groups were both significantly higher than those in the SA group at weeks 16 and 26.
Conclusion
Among patients with knee OA, intensive EA resulted in less pain and better function at week 8, compared with SA, and these effects persisted though week 26. Intensive MA had no benefit for knee OA at week 8, although it showed benefits during follow‐up.
Low-carbon economy is an economic model based on low energy consumption, low pollution and low emission. Energy-saving packaging design is an idea that guides the practice reform and development ...under the guidance of consumers’ green psychology. It takes the green design concept of modern eco-environmental protection and other development concepts as the main standard of packaging design application practice.
In order to change this situation, we should combine people’s formed green psychology, so as to find a way of green packaging design.
This paper discusses the application and development of energy-saving packaging design. Based on artificial intelligence (AI) technology, it realizes the combination of market and green environmental protection design, and improves product utilization and production efficiency. For judging the type of intelligent energy-saving packaging, the confidence weight database decision algorithm is adopted, and the basic principle is to assume that AI neural network forms the energy consumption vector.
For the long-term benefit of human survival, packaging designers should re-examine the relationship between design and natural environment, reduce the pollution components in packaging design, take environmental protection as the top priority of design, and establish a design concept that conforms to ecological ethics. Intelligent packaging technology realizes the integration and management of product packaging information, which is conducive to people’s better understanding of products and is of great significance to the development of low-carbon product packaging.
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