Encapsulating metal organic framework into hollow mesoporous carbon sphere as efficient oxygen bifunctional electrocatalyst

Applying metal organic frameworks (MOFs) in electrochemical systems is a currently emerging field owing to the rich metal nodes and highly specific surface area of MOFs. However, the problems for MOFs that need to be solved urgently are poor electrical conductivity and low ion transport. Here we present a facile in situ growth method for the rational synthesis of MOFs@hollow mesoporous carbon spheres (HMCS) yolk–shell-structured hybrid material for the first time. The size of the encapsulated Zeolitic Imidazolate Framework-67 (ZIF-67) is well controlled to 100 nm due to the spatial confinement effect of HMCS, and the electrical conductivity of ZIF-67 is also increased significantly. The ZIF@HMCS-25% hybrid material obtained exhibits a highly efficient oxygen reduction reaction activity with 0.823 V (vs. reversible hydrogen electrode) half-wave potential and an even higher kinetic current density (J_K = 13.8 mA cm⁻²) than commercial Pt/C. ZIF@HMCS-25% also displays excellent oxygen evolution reaction performance and the overpotential of ZIF@HMCS-25% at 10 mA cm⁻² is 407 mV. In addition, ZIF@HMCS-25% is further employed as an air electrode for a rechargeable Zn–air battery, exhibiting a high power density (120.2 mW cm⁻² at 171.4 mA cm⁻²) and long-term charge/discharge stability (80 h at 5 mA cm⁻²). This MOFs@HMCS yolk–shell design provides a versatile method for the application of MOFs as electrocatalysts directly.     

Efficient rare earth cerium(III) complex with nanosecond d−f emission for blue organic light-emitting diodes

In the field of RGB diodes, development of a blue organic light-emitting diode (OLED) is a challenge because of the lack of an emitter which simultaneously has a short excited state lifetime and a high theoretical external quantum efficiency (EQE). We demonstrate herein a blue emissive rare earth cerium(III) complex Ce-2 showing a high photoluminescence quantum yield of 95% and a short excited state lifetime of 52.0 ns in doped film, which is considerably faster than that achieved in typical efficient phosphorescence or thermally activated delayed fluorescence emitters (typical lifetimes >1 μs). The corresponding OLED shows a maximum EQE up to 20.8% and a still high EQE of 18.2% at 1000 cd m⁻², as well as an operation lifetime 70 times longer than that of a classic phosphorescence OLED. The excellent performance indicates that cerium(III) complex could be a candidate for efficient and stable blue OLEDs because of its spin- and parity-allowed d−f transition from the Ce³⁺ ion.     

A highly alkaline-stable metal oxide@metal–organic framework composite for high-performance electrochemical energy storage

Most metal–organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to alkaline aqueous solutions, thus precluding their use as potential electrode materials for electrochemical energy storage devices. Here, we present the design and synthesis of a highly alkaline-stable metal oxide@MOF composite, Co₃O₄ nanocube@Co-MOF (Co₃O₄@Co-MOF), via a controllable and facile one-pot hydrothermal method under highly alkaline conditions. The obtained composite possesses exceptional alkaline stability, retaining its original structure in 3.0 M KOH for at least 15 days. Benefitting from the exceptional alkaline stability, unique structure, and larger surface area, the Co₃O₄@Co-MOF composite shows a specific capacitance as high as 1020 F g⁻¹ at 0.5 A  g⁻¹ and a high cycling stability with only 3.3% decay after 5000 cycles at 5 A g⁻¹. The as-constructed solid-state flexible device exhibits a maximum energy density of 21.6 mWh cm⁻³.     

Direct transformation of dinitrogen: synthesis of N-containing organic compounds via N−C bond formation

N-containing organic compounds are of vital importance to lives. Practical synthesis of valuable N-containing organic compounds directly from dinitrogen (N₂), not through ammonia (NH₃), is a holy-grail in chemistry and chemical industry. An essential step for this transformation is the functionalization of the activated N₂ units/ligands to generate N−C bonds. Pioneering works of transition metal-mediated direct conversion of N₂ into organic compounds via N−C bond formation at metal-dinitrogen [N₂-M] complexes have generated diversified coordination modes and laid the foundation of understanding for the N−C bond formation mechanism. This review summarizes those major achievements and is organized by the coordination modes of the [N₂-M] complexes (end-on, side-on, end-on-side-on, etc.) that are involved in the N−C bond formation steps, and each part is arranged in terms of reaction types (N-alkylation, N-acylation, cycloaddition, insertion, etc.) between [N₂-M] complexes and carbon-based substrates. Additionally, earlier works on one-pot synthesis of organic compounds from N₂ via ill-defined intermediates are also briefed. Although almost all of the syntheses of N-containing organic compounds via direct transformation of N₂ so far in the literature are realized in homogeneous stoichiometric thermochemical reaction systems and are discussed here in detail, the sporadically reported syntheses involving photochemical, electrochemical, heterogeneous thermo-catalytic reactions, if any, are also mentioned. This review aims to provide readers with an in-depth understanding of the state-of-the-art and perspectives of future research particularly in direct catalytic and efficient conversion of N₂ into N-containing organic compounds under mild conditions, and to stimulate more research efforts to tackle this long-standing and grand scientific challenge.     

Correlation of Microalbuminuria with Estimated GFR (eGFR) by Cockcroft–Gault and MDRD Formula in Type 2 Diabetics and Hypertensives

Increase in urine albumin excretion rate (AER) precede a fall in glomerular filtration rate in patients developing diabetic chronic kidney disease (CKD). Our results have shown that 7 (50 %) of diabetic and hypertensive individuals with decreased GFR do not have increased AER. In this cross-sectional study, we measured AER of 75 patients with type 2 diabetes and hypertension by immunoturbidimetric method. We correlated the results with eGFR values obtained by Cockcroft–Gault and MDRD method. The method used was not a compensated method. We measured serum creatinine by modified Jaffe’s kinetic method in autoanalyzer XL-600. Analysis of data showed positive correlation between eGFR and microalbuminuria by both the methods with eGFR <60 mL/min/1.73 m². Pearson’s correlation co-efficient (r) was 0.9 (p = 0.0001) by Cockcroft–Gault formula and 0.69 (p = 0.0063) by MDRD formula. Our results concluded that there was positive correlation between AER and eGFR <60 mL/min/1.73 m². We have recognized that these two parameters provide a complimentary benefit in management of cases with CKD.     

Single lithium-ion channel polymer binder for stabilizing sulfur cathodes

Lithium–sulfur batteries have great potential for high-performance energy-storage devices, yet the severe diffusion of soluble polysulfide to electrolyte greatly limits their practical applications. To address the above issues, herein we design and synthesize a novel polymer binder with single lithium-ion channels allowing fast lithium-ion transport while blocking the shuttle of unnecessary polysulfide anions. In situ UV–vis spectroscopy measurements reveal that the prepared polymer binder has effective immobilization to polysulfide intermediates. As expected, the resultant sulfur cathode achieves an excellent specific capacity of 1310 mAh g⁻¹ at 0.2 C, high Coulombic efficiency of 99.5% at 0.5 C after 100 cycles and stable cycling performance for 300 cycles at 1 C (1 C = 1675 mA g⁻¹). This study reports a new avenue to assemble a polymer binder with a single lithium-ion channel for solving the serious problem of energy attenuation of lithium–sulfur batteries.     

Unprecedented strong and reversible atomic orbital hybridization enables a highly stable Li–S battery

The shuttle effect and excessive volume change of the sulfur cathode severely impede the industrial implementation of Li–S batteries. It is still highly challenging to find an efficient way to suppress the shuttle effect and volume expansion. Here, we report, for the first time, an innovative atomic orbital hybridization concept to construct the hierarchical hollow sandwiched sulfur nanospheres with double-polyaniline layers as the cathode material for large-scale high-performance Li–S batteries. This hierarchically 3D, cross-linked and stable sulfur–polyaniline backbone with interconnected disulfide bonds provides a new type and strong intrinsic chemical confinement of sulfur owing to the atomic orbital hybridization of Li 2s, S 3p, C 2p and N 2p. Crucially, such atomic orbital hybridization of sulfur sandwiched in the double sulfur–polyaniline network is highly reversible during the discharge/charge process and can very efficiently suppress the shuttle effect and volume expansion, contributing to a very high capacity of 1142 mAh g^–1 and an excellent stabilized capacity of 886 mAh g^–1 at 0.2 C after 500 cycles with a suppressed volume expansion and an unprecedented electrode integrity. This innovative atomic orbital hybridization concept can be extended to the preparation of other electrode materials to eliminate the shuttle effect and volume expansion in battery technologies. The present work also provides a commercially viable and up-scalable cathode material based on this strong and highly reversible atomic orbital hybridation for large-scale high-performance Li–S batteries.     

Charmonium and charmoniumlike states at the BESIII experiment

Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 5 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of the M1 transition ψ(2S) → γη_c(2S) and the discovery of the ψ₂(3823) state; and report on studies of charmoniumlike states, including the discoveries of the Z_c(3900) and Z_c(4020) tetraquark candidates, the resolution of the fine structure of the Y(4260) state, the discovery of the new production process e⁺e⁻ → γX(3872) and the uncovering of strong evidence for the commonality among the X(3872), Y(4260) and Z_c(3900) states. The prospects for further research at BESIII and proposed future facilities are also presented.     

Human activities aggravate nitrogen-deposition pollution to inland water over China

In the past three decades, China has built more than 87 000 dams with a storage capacity of ≈6560 km³ and the total surface area of inland water has increased by 6672 km². Leaching of N from fertilized soils to rivers is the main source of N pollution in China, but the exposure of a growing inland water area to direct atmospheric N deposition and N leaching caused by N deposition on the terrestrial ecosystem, together with increased N deposition and decreased N flow, also tends to raise N concentrations in most inland waters. The contribution of this previously ignored source of  N deposition to freshwaters is estimated in this study, as well as mitigation strategies. The results show that the annual amounts of N depositions ranged from 4.9 to 16.6 kg · ha⁻¹ · yr⁻¹ in the 1990s to exceeding 20 kg · ha⁻¹ · yr⁻¹ in the 2010s over most of regions in China, so the total mass of ΔN (the net contribution of N deposition to the increase in N concentration) for lakes, rivers and reservoirs change from 122.26 Gg N · yr⁻¹ in the 1990s to 237.75 Gg N · yr⁻¹ in the 2010s. It is suggested that reducing the N deposition from various sources, shortening the water-retention time in dams and decreasing the degree of regulation for rivers are three main measures for preventing a continuous increase in the N-deposition pollution to inland water in China.     

Mineralogy of the deep lower mantle in the presence of H2O

Understanding the mineralogy of the Earth''s interior is a prerequisite for unravelling the evolution and dynamics of our planet. Here, we conducted high pressure-temperature experiments mimicking the conditions of the deep lower mantle (DLM, 1800–2890 km in depth) and observed surprising mineralogical transformations in the presence of water. Ferropericlase, (Mg, Fe)O, which is the most abundant oxide mineral in Earth, reacts with H₂O to form a previously unknown (Mg, Fe)O₂H_x (x ≤ 1) phase. The (Mg, Fe)O₂H_x has a pyrite structure and it coexists with the dominant silicate phases, bridgmanite and post-perovskite. Depending on Mg content and geotherm temperatures, the transformation may occur at 1800 km for (Mg_0.6Fe_0.4)O or beyond 2300 km for (Mg_0.7Fe_0.3)O. The (Mg, Fe)O₂H_x is an oxygen excess phase that stores an excessive amount of oxygen beyond the charge balance of maximum cation valences (Mg²⁺, Fe³⁺ and H⁺). This important phase has a number of far-reaching implications including extreme redox inhomogeneity, deep-oxygen reservoirs in the DLM and an internal source for modulating oxygen in the atmosphere.     

Alloimmunization to Red Cells and the Association of Alloantibodies Formation with Splenectomy Among Transfusion-Dependent β-Thalassemia Major/HbE Patients

Severe hemolytic anemia in β-thalassemia major and β-thalassemias/HbE (β-TM) patients requires giving blood transfusions. Chronic blood transfusions lead to iron overload consequence with organs damage and risk of alloantibody-formation. This study evaluates the prevalence of red cell alloimmunization and estimates the risk of alloantibody-formation in chronic transfusion-dependent β-TM patients. This cross sectional study was conducted on 143 β-TM patients receiving regular transfusions. We tried to determine the frequency, types and factors influencing red cell alloimmunization in these transfusion-dependent β-TM patients. Median age of 25 (17.5 %) alloantibody-formation β-TM patients was 19.0 years (inter quartile 15.5–24.0 years). The alloantibodies were Anti-Rh (E) (13.1 %), Anti-Rh (D) (0.7 %). Thirty-four patients (23.8 %) of the sample had splenectomies of which 10 (29.4 %) had alloantibody-formation. The interval from first transfusion to antibody development varied from 1.5 to 14 years. Alloantibody-formation correlated with splenectomy and splenectomy correlated with number of transfusion (p < 0.005). In multiple logistic regression used to estimate the risk of alloantibodies formation with splenectomy; OR and 95 % CI were 2.88 (1.07–7.80), p = 0.037 after adjusting for other co-variates. The rate of red cell alloimmunization was 17.5 % and splenectomy associated with increased alloantibody-formation in these transfusion-dependent β-TM patients.     

Integration of bio-inspired lanthanide-transition metal cluster and P-doped carbon nitride for efficient photocatalytic overall water splitting

Photosynthesis in nature uses the Mn₄CaO₅ cluster as the oxygen-evolving center to catalyze the water oxidation efficiently in photosystem II. Herein, we demonstrate bio-inspired heterometallic LnCo₃ (Ln = Nd, Eu and Ce) clusters, which can be viewed as synthetic analogs of the CaMn₄O₅ cluster. Anchoring LnCo₃ on phosphorus-doped graphitic carbon nitrides (PCN) shows efficient overall water splitting without any sacrificial reagents. The NdCo₃/PCN-c photocatalyst exhibits excellent water splitting activity and a quantum efficiency of 2.0% at 350 nm. Ultrafast transient absorption spectroscopy revealed the transfer of a photoexcited electron and hole into the PCN and LnCo₃ for hydrogen and oxygen evolution reactions, respectively. A density functional theory (DFT) calculation showed the cooperative water activation on lanthanide and O−O bond formation on transition metal for water oxidation. This work not only prepares a synthetic model of a bio-inspired oxygen-evolving center but also provides an effective strategy to realize light-driven overall water splitting.     

Ferrimagnetic mPEG-b-PHEP copolymer micelles loaded with iron oxide nanocubes and emodin for enhanced magnetic hyperthermia–chemotherapy

As a non-invasive therapeutic method without penetration-depth limitation, magnetic hyperthermia therapy (MHT) under alternating magnetic field (AMF) is a clinically promising thermal therapy. However, the poor heating conversion efficiency and lack of stimulus–response obstruct the clinical application of magnetofluid-mediated MHT. Here, we develop a ferrimagnetic polyethylene glycol-poly(2-hexoxy-2-oxo-1,3,2-dioxaphospholane) (mPEG-b-PHEP) copolymer micelle loaded with hydrophobic iron oxide nanocubes and emodin (denoted as EMM). Besides an enhanced magnetic resonance (MR) contrast ability (r₂ = 271 mM⁻¹ s⁻¹) due to the high magnetization, the specific absorption rate (2518 W/g at 35 kA/m) and intrinsic loss power (6.5 nHm²/kg) of EMM are dozens of times higher than the clinically available iron oxide nanoagents (Feridex and Resovist), indicating the high heating conversion efficiency. Furthermore, this composite micelle with a flowable core exhibits a rapid response to magnetic hyperthermia, leading to an AMF-activated supersensitive drug release. With the high magnetic response, thermal sensitivity and magnetic targeting, this supersensitive ferrimagnetic nanocomposite realizes an above 70% tumor cell killing effect at an extremely low dosage (10 μg Fe/mL), and the tumors on mice are completely eliminated after the combined MHT–chemotherapy.     

Changes in China’s lakes: climate and human impacts

Lakes have played a critical role in providing water and ecosystem services for people and other organisms in China for millennia. However, accelerating climate change and economic boom have resulted in unprecedented changes in these valuable lakes. Using Landsat images covering the entity of the country, we explored the changes in China’s lakes and the associated driving forces over the last 30 years (i.e. mid-1980s to 2015). We discovered that China’s lakes have changed with divergent regional trends: in the sparsely populated Tibetan Plateau, lakes are abundant and the lake area has increased dramatically from 38 596 to 46 831 km² (i.e. increased by 8235 km², or 21.3%), whereas, in the densely populated northern and eastern regions, lakes are relatively scarce and the lake area has decreased from 36 659 to 33 657 km² (i.e. decreased by 3002 km², or 8.2%). In particular, severe lake decreases occurred in the Mongolia-Xinjiang Plateau and the Eastern Plain (−2151 km²). Statistical analyses indicated that climate was the most important factor controlling lake changes in the Tibetan Plateau, the Yun-Gui Plateau and the Northeast Plain. However, the strength of climatic control on lake changes was low in the Eastern Plain and the Mongolia-Xinjiang Plateau, where human activities, e.g. impoldering, irrigation and mining, have caused serious impacts on lakes. Further lake changes will exacerbate regional imbalances between lake resources and population distribution, and thus may increase the risk of water-resource crises in China.     

Control over π-π stacking of heteroheptacene-based nonfullerene acceptors for 16% efficiency polymer solar cells

Nonfullerene acceptors are being investigated for use in polymer solar cells (PSCs), with their advantages of extending the absorption range, reducing the energy loss and therefore enhancing the power conversion efficiency (PCE). However, to further boost the PCE, mobilities of these nonfullerene acceptors should be improved. For nonfullerene acceptors, the π–π stacking distance between cofacially stacked molecules significantly affects their mobility. Here, we demonstrate a strategy to increase the mobility of heteroheptacene-based nonfullerene acceptors by reducing their π–π stacking distances via control over the bulkiness of lateral side chains. Incorporation of 2-butyloctyl substituents into the nonfullerene acceptor (M36) leads to an increased mobility with a reduced π–π stacking distance of 3.45 Å. Consequently, M36 affords an enhanced PCE of 16%, which is the highest among all acceptor-donor-acceptor-type nonfullerene acceptors to date. This strategy of control over the bulkiness of side chains on nonfullerene acceptors should aid the development of more efficient PSCs.     

High-entropy-alloy nanoparticles with 21 ultra-mixed elements for efficient photothermal conversionOA

Multi-metallic nanoparticles have been proven to be an efficient photothermal conversion material, for which the optical absorption can be broadened through the interband transitions(IBTs), but it remains a challenge due to the strong immiscibility among the repelling combinations. Here, assisted by an extremely high evaporation temperature, ultra-fast cooling and vapor-pressure strategy, the arc-discharged plasma method was employed to synthesize ultra-mixed multi-metallic nanoparticles compose...     

A photon-controlled diode with a new signal-processing behavior

The photodetector is a key component in optoelectronic integrated circuits. Although there are various device structures and mechanisms, the output current changes either from rectified to fully-on or from fully-off to fully-on after illumination. A device that changes the output current from fully-off to rectified should be possible. We report the first photon-controlled diode based on a n/n⁻ molybdenum disulfide junction. Schottky junctions formed at the cathode and anode either prevent or allow the device to be rectifying, so that the output current of the device changes from fully-off to rectified. By increasing the thickness of the photogating layer, the behavior of the device changes from a photodetector to a multifunctional photomemory with the highest non-volatile responsivity of 4.8 × 10⁷ A/W and the longest retention time of 6.5 × 10⁶ s reported so far. Furthermore, a 3 × 3 photomemory array without selectors shows no crosstalk between adjacent devices and has optical signal-processing functions including wavelength and power-density selectivity.     

Altering the rate-determining step over cobalt single clusters leading to highly efficient ammonia synthesis

Activation of high-energy triple-bonds of N₂ is the most significant bottleneck of ammonia synthesis under ambient conditions. Here, by importing cobalt single clusters as strong electron-donating promoter into the catalyst, the rate-determining step of ammonia synthesis is altered to the subsequent proton addition so that the barrier of N₂ dissociation can be successfully overcome. As revealed by density functional theory calculations, the N₂ dissociation becomes exothermic over the cobalt single cluster upon the strong electron backdonation from metal to the N₂ antibonding orbitals. The energy barrier of the positively shifted rate-determining step is also greatly reduced. At the same time, advanced sampling molecular dynamics simulations indicate a barrier-less process of the N₂ approaching the active sites that greatly facilitates the mass transfer. With suitable thermodynamic and dynamic property, a high ammonia yield rate of 76.2 μg h^–1 mg and superior Faradaic efficiency of 52.9% were simultaneously achieved.     

Selective electrochemical production of hydrogen peroxide at zigzag edges of exfoliated molybdenum telluride nanoflakes

The two-electron reduction of molecular oxygen represents an effective strategy to enable the green, mild and on-demand synthesis of hydrogen peroxide. Its practical viability, however, hinges on the development of advanced electrocatalysts, preferably composed of non-precious elements, to selectively expedite this reaction, particularly in acidic medium. Our study here introduces 2H-MoTe₂ for the first time as the efficient non-precious-metal-based electrocatalyst for the electrochemical production of hydrogen peroxide in acids. We show that exfoliated 2H-MoTe₂ nanoflakes have high activity (onset overpotential ∼140 mV and large mass activity of 27 A g⁻¹ at 0.4 V versus reversible hydrogen electrode), great selectivity (H₂O₂ percentage up to 93%) and decent stability in 0.5 M H₂SO₄. Theoretical simulations evidence that the high activity and selectivity of 2H-MoTe₂ arise from the proper binding energies of HOO^* and O^* at its zigzag edges that jointly favor the two-electron reduction instead of the four-electron reduction of molecular oxygen.     

Robust prediction of hourly PM2.5 from meteorological data using LightGBM

Retrieving historical fine particulate matter (PM_2.5) data is key for evaluating the long-term impacts of PM_2.5 on the environment, human health and climate change. Satellite-based aerosol optical depth has been used to estimate PM_2.5, but estimations have largely been undermined by massive missing values, low sampling frequency and weak predictive capability. Here, using a novel feature engineering approach to incorporate spatial effects from meteorological data, we developed a robust LightGBM model that predicts PM_2.5 at an unprecedented predictive capacity on hourly (R² = 0.75), daily (R² = 0.84), monthly (R² = 0.88) and annual (R² = 0.87) timescales. By taking advantage of spatial features, our model can also construct hourly gridded networks of PM_2.5. This capability would be further enhanced if meteorological observations from regional stations were incorporated. Our results show that this model has great potential in reconstructing historical PM_2.5 datasets and real-time gridded networks at high spatial-temporal resolutions. The resulting datasets can be assimilated into models to produce long-term re-analysis that incorporates interactions between aerosols and physical processes.