Showing papers by "Nanjing University published in 2020"

Global Carbon Budget 2020

Abstract: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate – the “global carbon budget” – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2010–2019), EFOS was 9.6 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.4 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.6 ± 0.7 GtC yr−1. For the same decade, GATM was 5.1 ± 0.02 GtC yr−1 (2.4 ± 0.01 ppm yr−1), SOCEAN 2.5 ± 0.6 GtC yr−1, and SLAND 3.4 ± 0.9 GtC yr−1, with a budget imbalance BIM of −0.1 GtC yr−1 indicating a near balance between estimated sources and sinks over the last decade. For the year 2019 alone, the growth in EFOS was only about 0.1 % with fossil emissions increasing to 9.9 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.7 ± 0.5 GtC yr−1 when cement carbonation sink is included), and ELUC was 1.8 ± 0.7 GtC yr−1, for total anthropogenic CO2 emissions of 11.5 ± 0.9 GtC yr−1 (42.2 ± 3.3 GtCO2). Also for 2019, GATM was 5.4 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.6 ± 0.6 GtC yr−1, and SLAND was 3.1 ± 1.2 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 409.85 ± 0.1 ppm averaged over 2019. Preliminary data for 2020, accounting for the COVID-19-induced changes in emissions, suggest a decrease in EFOS relative to 2019 of about −7 % (median estimate) based on individual estimates from four studies of −6 %, −7 %, −7 % (−3 % to −11 %), and −13 %. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2019, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. Comparison of estimates from diverse approaches and observations shows (1) no consensus in the mean and trend in land-use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent discrepancy between the different methods for the ocean sink outside the tropics, particularly in the Southern Ocean. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Friedlingstein et al., 2019; Le Quere et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2020 (Friedlingstein et al., 2020).

Coronavirus Disease 2019 (COVID-19): A Perspective from China

Abstract: In December 2019, an outbreak of severe acute respiratory syndrome coronavirus 2 infection occurred in Wuhan, Hubei Province, China, and spread across China and beyond. On February 12, 2020, the World Health Organization officially named the disease caused by the novel coronavirus as coronavirus disease 2019 (COVID-19). Because most patients infected with COVID-19 had pneumonia and characteristic CT imaging patterns, radiologic examinations have become vital in early diagnosis and the assessment of disease course. To date, CT findings have been recommended as major evidence for clinical diagnosis of COVID-19 in Hubei, China. This review focuses on the etiology, epidemiology, and clinical symptoms of COVID-19 while highlighting the role of chest CT in prevention and disease control.

Accelerated discovery of CO 2 electrocatalysts using active machine learning

Abstract: The rapid increase in global energy demand and the need to replace carbon dioxide (CO2)-emitting fossil fuels with renewable sources have driven interest in chemical storage of intermittent solar and wind energy1,2. Particularly attractive is the electrochemical reduction of CO2 to chemical feedstocks, which uses both CO2 and renewable energy3–8. Copper has been the predominant electrocatalyst for this reaction when aiming for more valuable multi-carbon products9–16, and process improvements have been particularly notable when targeting ethylene. However, the energy efficiency and productivity (current density) achieved so far still fall below the values required to produce ethylene at cost-competitive prices. Here we describe Cu-Al electrocatalysts, identified using density functional theory calculations in combination with active machine learning, that efficiently reduce CO2 to ethylene with the highest Faradaic efficiency reported so far. This Faradaic efficiency of over 80 per cent (compared to about 66 per cent for pure Cu) is achieved at a current density of 400 milliamperes per square centimetre (at 1.5 volts versus a reversible hydrogen electrode) and a cathodic-side (half-cell) ethylene power conversion efficiency of 55 ± 2 per cent at 150 milliamperes per square centimetre. We perform computational studies that suggest that the Cu-Al alloys provide multiple sites and surface orientations with near-optimal CO binding for both efficient and selective CO2 reduction17. Furthermore, in situ X-ray absorption measurements reveal that Cu and Al enable a favourable Cu coordination environment that enhances C–C dimerization. These findings illustrate the value of computation and machine learning in guiding the experimental exploration of multi-metallic systems that go beyond the limitations of conventional single-metal electrocatalysts. Machine learning predicts Cu-Al electrocatalysts provide better efficiency and productivity than copper when using intermittent renewable electricity to convert carbon dioxide to useful chemicals and fuels.

Recent developments in the general atomic and molecular electronic structure system.

Abstract: A discussion of many of the recently implemented features of GAMESS (General Atomic and Molecular Electronic Structure System) and LibCChem (the C++ CPU/GPU library associated with GAMESS) is presented. These features include fragmentation methods such as the fragment molecular orbital, effective fragment potential and effective fragment molecular orbital methods, hybrid MPI/OpenMP approaches to Hartree-Fock, and resolution of the identity second order perturbation theory. Many new coupled cluster theory methods have been implemented in GAMESS, as have multiple levels of density functional/tight binding theory. The role of accelerators, especially graphical processing units, is discussed in the context of the new features of LibCChem, as it is the associated problem of power consumption as the power of computers increases dramatically. The process by which a complex program suite such as GAMESS is maintained and developed is considered. Future developments are briefly summarized.

Correlated electronic phases in twisted bilayer transition metal dichalcogenides

Abstract: In narrow electron bands in which the Coulomb interaction energy becomes comparable to the bandwidth, interactions can drive new quantum phases. Such flat bands in twisted graphene-based systems result in correlated insulator, superconducting and topological states. Here we report evidence of low-energy flat bands in twisted bilayer WSe2, with signatures of collective phases observed over twist angles that range from 4 to 5.1°. At half-band filling, a correlated insulator appeared that is tunable with both twist angle and displacement field. At a 5.1° twist, zero-resistance pockets were observed on doping away from half filling at temperatures below 3 K, which indicates a possible transition to a superconducting state. The observation of tunable collective phases in a simple band, which hosts only two holes per unit cell at full filling, establishes twisted bilayer transition metal dichalcogenides as an ideal platform to study correlated physics in two dimensions on a triangular lattice. Tunable correlated states are observed in twist bilayer WSe2 over a range of twist angles, with signatures of superconductivity for a twist of 5.1°.

Bandgap engineering of two-dimensional semiconductor materials

Abstract: Semiconductors are the basis of many vital technologies such as electronics, computing, communications, optoelectronics, and sensing. Modern semiconductor technology can trace its origins to the invention of the point contact transistor in 1947. This demonstration paved the way for the development of discrete and integrated semiconductor devices and circuits that has helped to build a modern society where semiconductors are ubiquitous components of everyday life. A key property that determines the semiconductor electrical and optical properties is the bandgap. Beyond graphene, recently discovered two-dimensional (2D) materials possess semiconducting bandgaps ranging from the terahertz and mid-infrared in bilayer graphene and black phosphorus, visible in transition metal dichalcogenides, to the ultraviolet in hexagonal boron nitride. In particular, these 2D materials were demonstrated to exhibit highly tunable bandgaps, achieved via the control of layers number, heterostructuring, strain engineering, chemical doping, alloying, intercalation, substrate engineering, as well as an external electric field. We provide a review of the basic physical principles of these various techniques on the engineering of quasi-particle and optical bandgaps, their bandgap tunability, potentials and limitations in practical realization in future 2D device technologies.

METTL3-mediated m6A modification of HDGF mRNA promotes gastric cancer progression and has prognostic significance

Abstract: Objective N6-methyladenosine (m6A) RNA methylation and its associated methyltransferase METTL3 are involved in tumour initiation and progression via the regulation of RNA function. This study explored the biological function and clinical significance of METTL3 in gastric cancer (GC). Design The prognostic value of METTL3 expression was evaluated using tissue microarray and immunohistochemical staining analyses in a human GC cohort. The biological role and mechanism of METTL3 in GC tumour growth and liver metastasis were determined in vitro and in vivo. Results The level of m6A RNA was significantly increased in GC, and METTL3 was the main regulator involved in the abundant m6A RNA modification. METTL3 expression was significantly elevated in GC tissues and associated with poor prognosis. Multivariate Cox regression analysis revealed that METTL3 expression was an independent prognostic factor and effective predictor in human patients with GC. Moreover, METTL3 overexpression promoted GC proliferation and liver metastasis in vitro and in vivo. Mechanistically, P300-mediated H3K27 acetylation activation in the promoter of METTL3 induced METTL3 transcription, which stimulated m6A modification of HDGF mRNA, and the m6A reader IGF2BP3 then directly recognised and bound to the m6A site on HDGF mRNA and enhanced HDGF mRNA stability. Secreted HDGF promoted tumour angiogenesis, while nuclear HDGF activated GLUT4 and ENO2 expression, followed by an increase in glycolysis in GC cells, which was correlated with subsequent tumour growth and liver metastasis. Conclusions Elevated METTL3 expression promotes tumour angiogenesis and glycolysis in GC, indicating that METTL3 expression is a potential prognostic biomarker and therapeutic target for human GC.

Clinical Course and Outcomes of 344 Intensive Care Patients with COVID-19.

Abstract: With the dramatic increase of confirmed cases of coronavirus disease (COVID-19) and the increasing death toll in China, timely and effective management of severely and critically ill patients appears to be particularly important. Previous studies on COVID-19 mainly described the general features of patients (1). However, little attention has been paid to clinical characteristics and outcomes of intensive care patients, data on whom are scarce but are of paramount importance to reduce mortality. Some of the results of these studies have been previously reported in the form of an abstract (2).

All-perovskite tandem solar cells with 24.2% certified efficiency and area over 1 cm2 using surface-anchoring zwitterionic antioxidant

Abstract: Monolithic all-perovskite tandem solar cells offer an avenue to increase power conversion efficiency beyond the limits of single-junction cells. It is an important priority to unite efficiency, uniformity and stability, yet this has proven challenging because of high trap density and ready oxidation in narrow-bandgap mixed lead–tin perovskite subcells. Here we report simultaneous enhancements in the efficiency, uniformity and stability of narrow-bandgap subcells using strongly reductive surface-anchoring zwitterionic molecules. The zwitterionic antioxidant inhibits Sn2+ oxidation and passivates defects at the grain surfaces in mixed lead–tin perovskite films, enabling an efficiency of 21.7% (certified 20.7%) for single-junction solar cells. We further obtain a certified efficiency of 24.2% in 1-cm2-area all-perovskite tandem cells and in-lab power conversion efficiencies of 25.6% and 21.4% for 0.049 cm2 and 12 cm2 devices, respectively. The encapsulated tandem devices retain 88% of their initial performance following 500 hours of operation at a device temperature of 54–60 °C under one-sun illumination in ambient conditions. Ensuring both stability and efficiency in mixed lead–tin perovskite solar cells is crucial to the development of all-perovskite tandems. Xiao et al. use an antioxidant zwitterionic molecule to suppress tin oxidation thus enabling large-area tandem cells with 24.2% efficiency and operational stability over 500 hours.

Near-real-time monitoring of global CO2 emissions reveals the effects of the COVID-19 pandemic

Abstract: The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO2) emissions. Here we present daily estimates of country-level CO2 emissions for different sectors based on near-real-time activity data. The key result is an abrupt 8.8% decrease in global CO2 emissions (-1551 Mt CO2) in the first half of 2020 compared to the same period in 2019. The magnitude of this decrease is larger than during previous economic downturns or World War II. The timing of emissions decreases corresponds to lockdown measures in each country. By July 1st, the pandemic's effects on global emissions diminished as lockdown restrictions relaxed and some economic activities restarted, especially in China and several European countries, but substantial differences persist between countries, with continuing emission declines in the U.S. where coronavirus cases are still increasing substantially.

From high-touch to high-tech: COVID-19 drives robotics adoption

Abstract: Global economic and social life has been severely challenged since the World Health Organization (WHO) declared the COVID-19 disease a pandemic. Travel, tourism and hospitality, in particular, has ...

Cathode engineering with perylene-diimide interlayer enabling over 17% efficiency single-junction organic solar cells.

Abstract: In organic solar cells (OSCs), cathode interfacial materials are generally designed with highly polar groups to increase the capability of lowering the work function of cathode. However, the strong polar group could result in a high surface energy and poor physical contact at the active layer surface, posing a challenge for interlayer engineering to address the trade-off between device stability and efficiency. Herein, we report a hydrogen-bonding interfacial material, aliphatic amine-functionalized perylene-diimide (PDINN), which simultaneously down-shifts the work function of the air stable cathodes (silver and copper), and maintains good interfacial contact with the active layer. The OSCs based on PDINN engineered silver-cathode demonstrate a high power conversion efficiency of 17.23% (certified value 16.77% by NREL) and high stability. Our results indicate that PDINN is an effective cathode interfacial material and interlayer engineering via suitable intermolecular interactions is a feasible approach to improve device performance of OSCs. It is desired to design cathode interfacial layers to simultaneously improve the efficiency and stability of organic solar cells and tune the cathode properties. Here, Yao et al. develop such interfacial layers for the best donor-acceptor system and achieve a high certified efficiency close to 17%.

Treatment with convalescent plasma for COVID-19 patients in Wuhan, China.

Abstract: The discovery of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the outbreak of coronavirus disease 2019 (COVID-19) are causing public health emergencies. A handful pieces of literature have summarized its clinical and radiologic features, whereas therapies for COVID-19 are rather limited. To evaluate the efficacy of convalescent plasma therapy in COVID-19 patients, we did this timely descriptive study. Six laboratory-confirmed COVID-19 patients were enrolled and received the transfusion of ABO-compatible convalescent plasma. The efficacy of this intervention was determined by the alleviation of symptoms, changes in radiologic abnormalities and laboratory tests. No obvious adverse effect observed during the treatment. Transfusion of convalescent plasma led to a resolution of ground-glass opacities and consolidation in patients #1, #2, #3, #4, and #6. In patients #1 and #5 who presented with SARS-CoV-2 in throat swab, convalescent plasma therapy elicited an elimination of the virus. Serologic analysis indicated an immediate increase in anti-SARS-CoV-2 antibody titers in patients #2 and #3, but not in patient #1. This study indicates that convalescent plasma therapy is effective and specific for COVID-19. This intervention has a special significance for eliminating SARS-CoV-2 and is believed to be a promising state-of-the-art therapy during COVID-19 pandemic crisis.

Ultrathin ZnIn 2 S 4 Nanosheets Anchored on Ti 3 C 2 T X MXene for Photocatalytic H 2 Evolution

Abstract: Photocatalysts derived from semiconductor heterojunctions that harvest solar energy and catalyze reactions still suffer from low solar-to-hydrogen conversion efficiency. Now, MXene (Ti3 C2 TX ) nanosheets (MNs) are used to support the in situ growth of ultrathin ZnIn2 S4 nanosheets (UZNs), producing sandwich-like hierarchical heterostructures (UZNs-MNs-UZNs) for efficient photocatalytic H2 evolution. Opportune lateral epitaxy of UZNs on the surface of MNs improves specific surface area, pore diameter, and hydrophilicity of the resulting materials, all of which could be beneficial to the photocatalytic activity. Owing to the Schottky junction and ultrathin 2D structures of UZNs and MNs, the heterostructures could effectively suppress photoexcited electron-hole recombination and boost photoexcited charge transfer and separation. The heterostructure photocatalyst exhibits improved photocatalytic H2 evolution performance (6.6 times higher than pristine ZnIn2 S4 ) and excellent stability.

Encephalitis as a clinical manifestation of COVID-19.

Abstract: With great interest, we read the paper “Nervous system involvement after infection with COVID-19 and other coronaviruses”. The authors speculated that SARS-CoV-2 may cause neurological damages (Wu et al., 2020). Herein, we provided clinical evidence showing the central nervous system (CNS) involvement for SARS-CoV-2. A Wuhan male had fever, shortness of breath, and myalgia since Jan 28. On Feb 10, his disease deteriorated and his consciousness suddenly progressed to confusion. Laboratory test indicated low WBC count (3.3 × 10/L) and lymphopenia (0.8 × 10/L). Skull computer tomography (CT) was normal (Fig. 1A), while chest CT showed multiple subpleural ground glass opacities (GGOs) (Fig. 1B). The patient was positive for SARS-CoV-2 and sent to our institution. On physical examination, vital signs were stable without altered consciousness. Meningeal irritation signs (including nuchal rigidity, Kernig sign and Brudzinski sign) and extensor plantar response were present. Arterial blood gas analysis indicted PO2/FiO2 ratio of 240 mmHg. This COVID19 patient was treated with arbidol and oxygen therapy, whereas his consciousness was not improved. Lumbar puncture was performed on Feb 16, and the cerebrospinal fluid (CSF) pressure was 220 mmHg. Laboratory tests with CSF showed WBC (0.001 × 10/L), protein (0.27 g/L), ADA (0.17 U/L) and sugar (3.14 mmol/L) contents within normal limits. The CSF specimen was further tested for SARS-CoV-2 but the result was negative. This patient did not have evidence of bacterial or tuberculous infection of the CNS. After careful evaluation by neurologic experts, encephalitis associated with SARS-CoV-2 infection was concluded. Treatment at this moment was largely supportive, including mannitol infusion. Intriguingly, the patient’s consciousness generally ameliorated since Feb 20, and chest CT suggested a resolution of GGOs (Fig. 1B). His consciousness was completely clear on Feb 24. Two consecutive throat swab tests were negative for SARS-CoV-2. The patient was discharged from hospital on Feb 27. This letter describes a COVID-19 case who presented as encephalitis. To the best of our knowledge, this is an unusual manifestation of COVID-19. Fortunately, encephalitic associate with SARS-CoV-2 is selflimited. Although the definitive diagnosis of viral encephalitis largely depends on virus isolation, this is difficult for COVID-19 because SARSCoV-2 dissemination is transient and its CSF titer may be extremely low. Consistently, anti-SARS-CoV-2 IgM and IgG were not detectable in the patient’s CSF sample (unpublished data). Therefore, physical evaluation of neurological symptom is important to lead a presumptive diagnosis, as we have mentioned in this case. The pathophysiological characteristic of SARS-CoV-2 associated encephalitis is not fully understood. In agreement with Wu and colleagues (Wu et al., 2020), we speculate that SARS-CoV-2-induced immunologic response may cause inflammatory injury and edema, as a consequence, leading to alterations in consciousness. With the clearance of virus and the use of mannitol, the CSF pressure gradually reduces and the patient’s consciousness gradually improves. This might be a rational explanation for the self-limited property of SARS-CoV-2 associated encephalitis. Collectively, this report indicated that CNS may be involved in COVID-19 and highlights the diagnostic and therapeutic approaches to SARS-CoV-2 associated encephalitis.

Evolutionary V2X Technologies Toward the Internet of Vehicles: Challenges and Opportunities

Abstract: To enable large-scale and ubiquitous automotive network access, traditional vehicle-to-everything (V2X) technologies are evolving to the Internet of Vehicles (IoV) for increasing demands on emerging advanced vehicular applications, such as intelligent transportation systems (ITS) and autonomous vehicles. In recent years, IoV technologies have been developed and achieved significant progress. However, it is still unclear what is the evolution path and what are the challenges and opportunities brought by IoV. For the aforementioned considerations, this article provides a thorough survey on the historical process and status quo of V2X technologies, as well as demonstration of emerging technology developing directions toward IoV. We first review the early stage when the dedicated short-range communications (DSRC) was issued as an important initial beginning and compared the cellular V2X with IEEE 802.11 V2X communications in terms of both the pros and cons. In addition, considering the advent of big data and cloud-edge regime, we highlight the key technical challenges and pinpoint the opportunities toward the big data-driven IoV and cloud-based IoV, respectively. We believe our comprehensive survey on evolutionary V2X technologies toward IoV can provide beneficial insights and inspirations for both academia and the IoV industry.

Orbital angular momentum holography for high-security encryption

Abstract: Holography has been identified as a vital platform for three-dimensional displays, optical encryption, microscopy and artificial intelligence through different physical dimensions. However, unlike the wavelength and polarization divisions, orbital angular momentum (OAM) of light, despite its helical wavefront being an independent physical dimension, has not been implemented as an information carrier for holography due to the lack of helical mode index selectivity in the Bragg diffraction formula. Here, we demonstrate OAM holography by discovering strong OAM selectivity in the spatial-frequency domain without a theoretical helical mode index limit. As such, OAM holography allows the multiplexing of a wide range of OAM-dependent holographic images with a helical mode index spanning from −50 to 50, leading to a 10 bit OAM-encoded hologram for high-security optical encryption. Our results showing up to 210 OAM-dependent distinctive holographic images mark a new path to achieving ultrahigh-capacity holographic information systems harnessing the previously inaccessible OAM division. The orbital angular momentum degree of freedom is used to demonstrate 10 bit holographic images with a helical mode index spanning from −50 to 50.

Functional DNA Regulated CRISPR-Cas12a Sensors for Point-of-Care Diagnostics of Non-Nucleic-Acid Targets.

Abstract: Beyond its extraordinary genome editing ability, the CRISPR-Cas systems have opened a new era of biosensing applications due to its high base resolution and isothermal signal amplification. However, the reported CRISPR-Cas sensors are largely only used for the detection of nucleic acids with limited application for non-nucleic-acid targets. To realize the full potential of the CRISPR-Cas sensors and broaden their applications for detection and quantitation of non-nucleic-acid targets, we herein report CRISPR-Cas12a sensors that are regulated by functional DNA (fDNA) molecules such as aptamers and DNAzymes that are selective for small organic molecule and metal ion detection. The sensors are based on the Cas12a-dependent reporter system consisting of Cas12a, CRISPR RNA (crRNA), and its single-stranded DNA substrate labeled with a fluorophore and quencher at each end (ssDNA-FQ), and fDNA molecules that can lock a DNA activator for Cas12a-crRNA, preventing the ssDNA cleavage function of Cas12a in the absence of the fDNA targets. The presence of fDNA targets can trigger the unlocking of the DNA activator, which can then activate the cleavage of ssDNA-FQ by Cas12a, resulting in an increase of the fluorescent signal detectable by commercially available portable fluorimeters. Using this method, ATP and Na+ have been detected quantitatively under ambient temperature (25 °C) using a simple and fast detection workflow (two steps and <15 min), making the fDNA-regulated CRISPR system suitable for field tests or point-of-care diagnostics. Since fDNAs can be obtained to recognize a wide range of targets, the methods demonstrated here can expand this powerful CRISPR-Cas sensor system significantly to many other targets and thus provide a new toolbox to significantly expand the CRISPR-Cas system into many areas of bioanalytical and biomedical applications.

Selective Phosphate Removal from Water and Wastewater using Sorption: Process Fundamentals and Removal Mechanisms.

Abstract: Eutrophication of water bodies is a serious and widespread environmental problem. Achieving low levels of phosphate concentration to prevent eutrophication is one of the important goals of the wastewater engineering and surface water management. Meeting the increasingly stringent standards is feasible in using a phosphate-selective sorption system. This critical review discusses the most fundamental aspects of selective phosphate removal processes and highlights gains from the latest developments of phosphate-selective sorbents. Selective sorption of phosphate over other competing anions can be achieved based on their differences in acid-base properties, geometric shapes, and metal complexing abilities. Correspondingly, interaction mechanisms between the phosphate and sorbent are categorized as hydrogen bonding, shape complementarity, and inner-sphere complexation, and their representative sorbents are organic-functionalized materials, molecularly imprinted polymers, and metal-based materials, respectively. Dominating factors affecting the phosphate sorption performance of these sorbents are critically examined, along with a discussion of some overlooked facts regarding the development of high-performance sorbents for selective phosphate removal from water and wastewater.

Global projections of future urban land expansion under shared socioeconomic pathways

Abstract: Despite its small land coverage, urban land and its expansion have exhibited profound impacts on global environments. Here, we present the scenario projections of global urban land expansion under the framework of the shared socioeconomic pathways (SSPs). Our projections feature a fine spatial resolution of 1 km to preserve spatial details. The projections reveal that although global urban land continues to expand rapidly before the 2040s, China and many other Asian countries are expected to encounter substantial pressure from urban population decline after the 2050s. Approximately 50–63% of the newly expanded urban land is expected to occur on current croplands. Global crop production will decline by approximately 1–4%, corresponding to the annual food needs for a certain crop of 122–1389 million people. These findings stress the importance of governing urban land development as a key measure to mitigate its negative impacts on food production. Shared socioeconomic pathways (SSPs) is a crucial scenario describing the potential of future socio-economic development. The authors here investigate long-term effects of various government policies suggested by different SSPs on urban land and reveal the impact of future urban expansion on other land and food production.

PolarMask: Single Shot Instance Segmentation With Polar Representation

Abstract: In this paper, we introduce an anchor-box free and single shot instance segmentation method, which is conceptually simple, fully convolutional and can be used by easily embedding it into most off-the-shelf detection methods. Our method, termed PolarMask, formulates the instance segmentation problem as predicting contour of instance through instance center classification and dense distance regression in a polar coordinate. Moreover, we propose two effective approaches to deal with sampling high-quality center examples and optimization for dense distance regression, respectively, which can significantly improve the performance and simplify the training process. Without any bells and whistles, PolarMask achieves 32.9% in mask mAP with single-model and single-scale training/testing on the challenging COCO dataset. For the first time, we show that the complexity of instance segmentation, in terms of both design and computation complexity, can be the same as bounding box object detection and this much simpler and flexible instance segmentation framework can achieve competitive accuracy. We hope that the proposed PolarMask framework can serve as a fundamental and strong baseline for single shot instance segmentation task.

BBN: Bilateral-Branch Network With Cumulative Learning for Long-Tailed Visual Recognition

Abstract: Our work focuses on tackling the challenging but natural visual recognition task of long-tailed data distribution (i.e., a few classes occupy most of the data, while most classes have rarely few samples). In the literature, class re-balancing strategies (e.g., re-weighting and re-sampling) are the prominent and effective methods proposed to alleviate the extreme imbalance for dealing with long-tailed problems. In this paper, we firstly discover that these re-balancing methods achieving satisfactory recognition accuracy owe to that they could significantly promote the classifier learning of deep networks. However, at the same time, they will unexpectedly damage the representative ability of the learned deep features to some extent. Therefore, we propose a unified Bilateral-Branch Network (BBN) to take care of both representation learning and classifier learning simultaneously, where each branch does perform its own duty separately. In particular, our BBN model is further equipped with a novel cumulative learning strategy, which is designed to first learn the universal patterns and then pay attention to the tail data gradually. Extensive experiments on four benchmark datasets, including the large-scale iNaturalist ones, justify that the proposed BBN can significantly outperform state-of-the-art methods. Furthermore, validation experiments can demonstrate both our preliminary discovery and effectiveness of tailored designs in BBN for long-tailed problems. Our method won the first place in the iNaturalist 2019 large scale species classification competition, and our code is open-source and available at https://github.com/Megvii-Nanjing/BBN.

Constructing a Super‐Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

Abstract: Rechargeable aqueous zinc batteries (RAZB) have been re-evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal-organic framework (MOF) was constructed as front surface layer to maintain a super-saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super-saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm-2 , near 55-times that of bare Zn anodes. Moreover, aqueous MnO2 -Zn batteries delivered a reversible capacity of 180.3 mAh g-1 and maintained a high capacity retention of 88.9 % after 600 cycles with MnO2 mass loading up to 4.2 mg cm-2 .

Endovascular treatment versus standard medical treatment for vertebrobasilar artery occlusion (BEST): an open-label, randomised controlled trial.

Abstract: Summary Background Previous randomised trials have shown an overwhelming benefit of mechanical thrombectomy for treating patients with stroke caused by large vessel occlusion of the anterior circulation. Whether endovascular treatment is beneficial for vertebrobasilar artery occlusion remains unknown. In this study, we aimed to investigate the safety and efficacy of endovascular treatment of acute strokes due to vertebrobasilar artery occlusion. Methods We did a multicentre, randomised, open-label trial, with blinded outcome assessment of thrombectomy in patients presenting within 8 h of vertebrobasilar occlusion at 28 centres in China. Patients were randomly assigned (1:1) to endovascular therapy plus standard medical therapy (intervention group) or standard medical therapy alone (control group). The randomisation sequence was computer-generated and stratified by participating centres. Allocation concealment was implemented by use of sealed envelopes. The primary outcome was a modified Rankin scale (mRS) score of 3 or lower (indicating ability to walk unassisted) at 90 days, assessed on an intention-to-treat basis. The primary safety outcome was mortality at 90 days. Secondary safety endpoints included the rates of symptomatic intracranial haemorrhage, device-related complications, and other severe adverse events. The BEST trial is registered with ClinicalTrials.gov , NCT02441556 . Findings Between April 27, 2015, and Sept 27, 2017, we assessed 288 patients for eligibility. The trial was terminated early after 131 patients had been randomly assigned (66 patients to the intervention group and 65 to the control group) because of high crossover rate and poor recruitment. In the intention-to-treat analysis, there was no evidence of a difference in the proportion of participants with mRS 0–3 at 90 days according to treatment (28 [42%] of 66 patients in the intervention group vs 21 [32%] of 65 in the control group; adjusted odds ratio [OR] 1·74, 95% CI 0·81–3·74). Secondary prespecified analyses of the primary outcome, done to assess the effect of crossovers, showed higher rates of mRS 0–3 at 90 days in patients who actually received the intervention compared with those who received standard medical therapy alone in both per-protocol (28 [44%] of 63 patients with intervention vs 13 [25%] of 51 with standard therapy; adjusted OR 2·90, 95% CI 1·20–7·03) and as-treated (36 [47%] of 77 patients with intervention vs 13 [24%] of 54 with standard therapy; 3·02, 1·31–7·00) populations. The 90-day mortality was similar between groups (22 [33%] of 66 patients in the intervention vs 25 [38%] of 65 in the control group; p=0·54) despite a numerically higher prevalence of symptomatic intracranial haemorrhage in the intervention group. Interpretation There was no evidence of a difference in favourable outcomes of patients receiving endovascular therapy compared with those receiving standard medical therapy alone. Results might have been confounded by loss of equipoise over the course of the trial, resulting in poor adherence to the assigned study treatment and a reduced sample size due to the early termination of the study. Funding Jiangsu Provincial Special Program of Medical Science.