Potassium‐ion batteries (PIBs) are attractive for low‐cost and large‐scale energy storage applications, in which graphite is one of the most promising anodes. However, the large size and the high ...activity of K+ ions and the highly catalytic surface of graphite largely prevent the development of safe and compatible electrolytes. Here, a nonflammable, moderate‐concentration electrolyte is reported that is highly compatible with graphite anodes and that consists of fire‐retardant trimethyl phosphate (TMP) and potassium bis(fluorosulfonyl)imide (KFSI) in a salt/solvent molar ratio of 3:8. It shows unprecedented stability, as evidenced by its 74% capacity retention over 24 months of cycling (over 2000 cycles) at the 0.2 C current rate. Electrolyte structure and surface analyses show that this excellent cycling stability is due to the nearly 100% solvation of TMP molecules with K+ cations and the formation of FSI−‐derived F‐rich solid electrolyte interphase (SEI), which effectively suppresses the decomposition of the solvent molecules toward the graphite anode. Furthermore, excellent performance on high‐mass loaded graphite electrodes and in a full cell with perylenetetracarboxylic dianhydride cathode is demonstrated. This study highlights the importance of the compatibility of both electrolyte and the interface, and offers new opportunities to design the electrolyte–SEI nexus for safe and practical PIBs.
Nonflammable electrolytes show great advantages over conventional electrolytes in terms of both safety and performance, exhibiting high compatibility with graphite electrodes with the longest cycling performance (>2 years). The electrolyte structure and derived F‐rich solid electrolyte interphase jointly contribute to the superlong cycling stability of graphite electrode, which highlights the importance of the electrolyte compatibility and the interface.
The coronavirus disease 2019 (COVID-19) pandemic markedly changed human mobility patterns, necessitating epidemiological models that can capture the effects of these changes in mobility on the spread ...of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
. Here we introduce a metapopulation susceptible-exposed-infectious-removed (SEIR) model that integrates fine-grained, dynamic mobility networks to simulate the spread of SARS-CoV-2 in ten of the largest US metropolitan areas. Our mobility networks are derived from mobile phone data and map the hourly movements of 98 million people from neighbourhoods (or census block groups) to points of interest such as restaurants and religious establishments, connecting 56,945 census block groups to 552,758 points of interest with 5.4 billion hourly edges. We show that by integrating these networks, a relatively simple SEIR model can accurately fit the real case trajectory, despite substantial changes in the behaviour of the population over time. Our model predicts that a small minority of 'superspreader' points of interest account for a large majority of the infections, and that restricting the maximum occupancy at each point of interest is more effective than uniformly reducing mobility. Our model also correctly predicts higher infection rates among disadvantaged racial and socioeconomic groups
solely as the result of differences in mobility: we find that disadvantaged groups have not been able to reduce their mobility as sharply, and that the points of interest that they visit are more crowded and are therefore associated with higher risk. By capturing who is infected at which locations, our model supports detailed analyses that can inform more-effective and equitable policy responses to COVID-19.
Machine learning models trained on data from the outside world can be corrupted by
data poisoning
attacks that inject malicious points into the models’ training sets. A common defense against these ...attacks is
data sanitization
: first filter out anomalous training points before training the model. In this paper, we develop three attacks that can bypass a broad range of common data sanitization defenses, including anomaly detectors based on nearest neighbors, training loss, and singular-value decomposition. By adding just 3% poisoned data, our attacks successfully increase test error on the Enron spam detection dataset from 3 to 24% and on the IMDB sentiment classification dataset from 12 to 29%. In contrast, existing attacks which do not explicitly account for these data sanitization defenses are defeated by them. Our attacks are based on two ideas: (i) we coordinate our attacks to place poisoned points near one another, and (ii) we formulate each attack as a constrained optimization problem, with constraints designed to ensure that the poisoned points evade detection. As this optimization involves solving an expensive bilevel problem, our three attacks correspond to different ways of approximating this problem, based on influence functions; minimax duality; and the Karush–Kuhn–Tucker (KKT) conditions. Our results underscore the need to develop more robust defenses against data poisoning attacks.
Aqueous hybrid Zn‐based batteries (ZIBs), as a highly promising alternative to lithium‐ion batteries for grid application, have made considerable progress recently. However, few studies have been ...reported that investigate their working mechanism in detail. Here, the operando synchrotron X‐ray diffraction is employed to thoroughly investigate the operational mechanism of a hybrid LiFePO4(LFP)/Zn battery, which indicates only Li+ extraction/insertion from/into cathode during cycling. Based on this system, a cheap electrolyte additive, sodium dodecyl benzene sulfonate, is proposed to effectively enhance its electrochemical properties. The influence of the additive on the Zn anode and LFP cathode is comprehensively studied, respectively. The results show that the additive modifies the intrinsic deposit pattern of Zn2+ ions, rendering Zn plating/stripping highly reversible in an aqueous medium. On the other hand, the wettability of the LFP electrode is visibly a meliorated by introducing the surfactant additive, accelerating the Li‐ion diffusion at the LFP electrode/electrolyte interface, as indicated by the overpotential measurements. Benefiting from these effects, the Zn/LFP batteries deliver high rate capability and cycling stability in both coin cells and pouch cells.
Operando synchrotron is hired to study the working mechanism of aqueous hybrid Zn/LFP batteries. During the charge–discharge process, the LiFePO4 phase reversibly changes to FePO4 phase, indicating that only Li ions are involved in the cathode reaction even though Li+ ions are larger than Zn2+ ions.
Boosting charge transfer in materials is critical for applications involving charge carriers. Engineering ionic channels in electrode materials can create a skeleton to manipulate their ion and ...electron behaviors with favorable parameters to promote their capacity and stability. Here, tailoring of the atomic structure in layered potassium niobate (K4Nb6O17) nanosheets and facilitating their application in lithium and potassium storage by dehydration‐triggered lattice rearrangement is reported. The spectroscopy results reveal that the interatomic distances of the NbO coordination in the engineered K4Nb6O17 are slightly elongated with increased degrees of disorder. Specifically, the engineered K4Nb6O17 shows enhanced electrical and ionic conductivity, which can be attributed to the enlarged interlamellar spacing and subtle distortions in the fine atomic arrangements. Moreover, subsequent experimental results and calculations demonstrate that the energy barrier for Li+/K+ diffusion is significantly lower than that in pristine K4Nb6O17. Interestingly, the diffusion coefficient of K+ is one order of magnitude higher than that of Li+ , and the engineered K4Nb6O17 presents superior electrochemical performance for K+ to Li+ . This work offers an ionic engineering strategy to enable fast and durable charge transfer in materials, holding great promise for providing guidance for the material design of related energy storage systems.
Boosting charge transfer in materials is critical for applications involving charge carriers. Engineering ionic channels in electrode materials can create a skeleton to manipulate their ion/electron behaviors with favorable parameters to promote their performance. Tailoring of the atomic structure in layered potassium niobate and facilitating its application in Li/K storage by dehydration‐triggered lattice rearrangement is reported.
Potassium‐ion batteries (PIBs) are promising energy storage systems because of the abundance and low cost of potassium. The formidable challenge is to develop suitable electrode materials and ...electrolytes for accommodating the relatively large size and high activity of potassium. Herein, Bi‐based materials are reported as novel anodes for PIBs. Nanostructural design and proper selection of the electrolyte salt have been used to achieve excellent cycling performance. It is found that the potassiation of Bi undergoes a solid‐solution reaction, followed by two typical two‐phase reactions, corresponding to Bi ↔ Bi(K) and Bi(K) ↔ K5Bi4 ↔ K3Bi, respectively. By choosing potassium bis(fluorosulfonyl)imide (KFSI) to replace potassium hexafluorophosphate (KPF6) in carbonate electrolyte, a more stable solid electrolyte interphase layer is achieved and results in notably enhanced electrochemical performance. More importantly, the KFSI salt is very versatile and can significantly promote the electrochemical performance of other alloy‐based anode materials, such as Sn and Sb.
Bismuth stores potassium electrochemically via a solid‐solution reaction, followed by two typical two‐phase reactions, corresponding to Bi↔ Bi(K) and Bi(K) ↔ K5Bi4 ↔ K3Bi, respectively. Moreover, a more uniform, stable, conductive, and robust solid electrolyte interphase is achieved by replacing potassium hexafluorophosphate with potassium bis(fluorosulfonyl)imide (KFSI) and hence results in better cycling performance. The KFSI salt is also effective in other alloy‐based anode materials, such as Sn and Sb.
The quality of the solid electrolyte interphase (SEI) layer is the decisive factor for the electrochemical performance of Li‐metal‐based batteries. Due to the absence of effective bonding, a natural ...SEI layer may exfoliate from the Li anode during interfacial fluctuations. Here, a silane coupling agent is introduced to serve as an adhesion promoter to bridge these two dissimilar materials via both chemical bonding and physical intertwining effects. Its inorganic reactive groups can combine with the Li substrate by forming LiOSi bonds, while organic functional groups can take part in the formation of the SEI layer and thereby bond with SEI components. Li metal electrodes with silane coupling agent modification exhibit excellent electrochemical performance, even under extreme testing conditions. This modification layer with dense structure could also protect the Li metal from corrosion by air, evidenced by the comparable electrochemical activity of the modified Li metal electrodes even after being exposed in air for 2 h. This design provides a promising pathway for the development of Li metal electrodes that will be stable both in electrolyte and in air.
A dense modification layer of a silane coupling agent enables Li metal to be stable in air and during cycling. This layer firmly adheres to the Li metal surface by forming LiOSi bonds, and it connects with the solid electrolyte interphase layer by chemical bonds and physical intertwining effects.
An improvement in progression-free survival was shown with trastuzumab deruxtecan versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer in the progression-free survival ...interim analysis of the DESTINY-Breast03 trial. The aim of DESTINY-Breast03 was to compare the efficacy and safety of trastuzumab deruxtecan versus trastuzumab emtansine.
This open-label, randomised, multicentre, phase 3 trial was done in 169 study centres in North America, Asia, Europe, Australia, and South America. Eligible patients were aged 18 or older, had HER2-positive unresectable or metastatic breast cancer previously treated with trastuzumab and a taxane, had an Eastern Cooperative Oncology Group performance status 0–1, and at least one measurable lesion per Response Evaluation Criteria in Solid Tumours version 1.1. Patients were randomly assigned (1:1) to receive trastuzumab deruxtecan 5·4 mg/kg or trastuzumab emtansine 3·6 mg/kg, both administered by intravenous infusion every 3 weeks. Randomisation was stratified by hormone receptor status, previous treatment with pertuzumab, and history of visceral disease, and was managed through an interactive web-based system. Within each stratum, balanced block randomisation was used with a block size of four. Patients and investigators were not masked to the treatment received. The primary endpoint was progression-free survival by blinded independent central review. The key secondary endpoint was overall survival and this prespecified second overall survival interim analysis reports updated overall survival, efficacy, and safety results. Efficacy analyses were performed using the full analysis set. Safety analyses included all randomly assigned patients who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT03529110.
Between July 20, 2018, and June 23, 2020, 699 patients were screened for eligibility, 524 of whom were enrolled and randomly assigned to receive trastuzumab deruxtecan (n=261) or trastuzumab emtansine (n=263). Median duration of study follow-up was 28·4 months (IQR 22·1–32·9) with trastuzumab deruxtecan and 26·5 months (14·5–31·3) with trastuzumab emtansine. Median progression-free survival by blinded independent central review was 28·8 months (95% CI 22·4–37·9) with trastuzumab deruxtecan and 6·8 months (5·6–8·2) with trastuzumab emtansine (hazard ratio HR 0·33 95% CI 0·26–0·43; nominal p<0·0001). Median overall survival was not reached (95% CI 40·5 months–not estimable), with 72 (28%) overall survival events, in the trastuzumab deruxtecan group and was not reached (34·0 months–not estimable), with 97 (37%) overall survival events, in the trastuzumab emtansine group (HR 0·64 95% CI 0·47–0·87; p=0·0037). The number of grade 3 or worse treatment-emergent adverse events was similar in patients who received trastuzumab deruxtecan versus trastuzumab emtansine (145 56% patients versus 135 52% patients). Adjudicated drug-related interstitial lung disease or pneumonitis occurred in 39 (15%) patients treated with trastuzumab deruxtecan and eight (3%) patients treated with trastuzumab emtansine, with no grade 4 or 5 events in either group.
Trastuzumab deruxtecan showed a significant improvement in overall survival versus trastuzumab emtansine in patients with HER2-positive metastatic breast cancer, as well as the longest reported median progression-free survival, reaffirming trastuzumab deruxtecan as the standard of care in the second-line setting. A manageable safety profile of trastuzumab deruxtecan was confirmed with longer treatment duration.
Daiichi Sankyo and AstraZeneca.
Topological insulators have spurred worldwide interest, but their advantageous properties have scarcely been explored in terms of electrochemical energy storage, and their high‐rate capability and ...long‐term cycling stability still remain a significant challenge to harvest. p‐Type topological insulator SnSb2Te4 nanodots anchoring on few‐layered graphene (SnSb2Te4/G) are synthesized as a stable anode for high‐rate lithium‐ion batteries and potassium‐ion batteries through a ball‐milling method. These SnSb2Te4/G composite electrodes show ultralong cycle lifespan (478 mAh g−1 at 1 A g−1 after 1000 cycles) and excellent rate capability (remaining 373 mAh g−1 even at 10 A g−1) in Li‐ion storage owing to the rapid ion transport accelerated by the PN heterojunction, virtual electron highways provided by the conductive topological surface state, and extraordinary pseudocapacitive contribution, whose excellent phase reversibility is confirmed by synchrotron in situ X‐ray powder diffraction. Surprisingly, durable lifespan even at practical levels of mass loading (>10 mg cm−2) for Li‐ion storage and excellent K‐ion storage performance are also observed. This work provides new insights for designing high‐rate electrode materials by boosting conductive topological surfaces, atomic doping, and the interface interaction.
Topological insulator SnSb2Te4 nanodots coupled with few‐layered graphene show excellent rate capability and durable cycling performance for pseudocapacitive Li‐ion and K‐ion storage. They achieve this through boosting the conductive topological surfaces, atomic doping, and interface interaction, benefitting from the rapid ion transport accelerated by the PN heterojunction, virtual electron highways provided by the conductive topological surface state, and extraordinary pseudocapacitive contribution.
Radar Remote Sensing of Agricultural Canopies: A Review Steele-Dunne, Susan C.; McNairn, Heather; Monsivais-Huertero, Alejandro ...
IEEE journal of selected topics in applied earth observations and remote sensing,
05/2017, Letnik:
10, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Observations from spaceborne radar contain considerable information about vegetation dynamics. The ability to extract this information could lead to improved soil moisture retrievals and the ...increased capacity to monitor vegetation phenology and water stress using radar data. The purpose of this review paper is to provide an overview of the current state of knowledge with respect to backscatter from vegetated (agricultural) landscapes and to identify opportunities and challenges in this domain. Much of our understanding of vegetation backscatter from agricultural canopies stems from SAR studies to perform field-scale classification and monitoring. Hence, SAR applications, theory, and applications are considered here too. An overview will be provided of the knowledge generated from ground-based and airborne experimental campaigns that contributed to the development of crop classification, crop monitoring, and soil moisture monitoring applications. A description of the current vegetation modeling approaches will be given. A review of current applications of spaceborne radar will be used to illustrate the current state of the art in terms of data utilization. Finally, emerging applications, opportunities and challenges will be identified and discussed. Improved representation of vegetation phenology and water dynamics will be identified as essential to improve soil moisture retrievals, crop monitoring, and for the development of emerging drought/water stress applications.
PDF
