Mechanisms of soil organic carbon (SOC) stabilization have been widely studied due to their relevance in the global carbon cycle. No‐till (NT) has been frequently adopted to sequester SOC; however, ...limited information is available regarding whether sequestered SOC will be stabilized for long term. Thus, we reviewed the mechanisms affecting SOC stability in NT systems, including the priming effects (PE), molecular structure of SOC, aggregate protection, association with soil minerals, microbial properties, and environmental effects. Although a more steady‐state molecular structure of SOC is observed in NT compared with conventional tillage (CT), SOC stability may depend more on physical and chemical protection. On average, NT improves macro‐aggregation by 32.7%, and lowers SOC mineralization in macro‐aggregates compared with CT. Chemical protection is also important due to the direct adsorption of organic molecules and the enhancement of aggregation by soil minerals. Higher microbial activity in NT could also produce binding agents to promote aggregation and the formation of metal‐oxidant organic complexes. Thus, microbial residues could be stabilized in soils over the long term through their attachment to mineral surfaces and entrapment of aggregates under NT. On average, NT reduces SOC mineralization by 18.8% and PE intensities after fresh carbon inputs by 21.0% compared with CT (p < .05). Although higher temperature sensitivity (Q10) is observed in NT due to greater Q10 in macro‐aggregates, an increase of soil moisture regime in NT could potentially constrain the improvement of Q10. This review improves process‐based understanding of the physical and chemical mechanism of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in NT systems is likely to be stabilized over the long term.
Understanding the mechanisms of soil organic carbon (SOC) stability could be better to predict the SOC fate under climate change. Our review identified the factors affecting SOC stability and the roles of microbial residues in SOC stability regulated by physicochemical protection. This study provides systematic evidences of enhanced SOC accumulation under no‐till at upper soil depth, and improves process‐based understanding of the physical and chemical mechanisms of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in no‐till systems could be stabilized over the long term.
No‐till (NT) is a sustainable option because of its benefits in controlling erosion, saving labor, and mitigating climate change. However, a comprehensive assessment of soil pH response to NT is ...still lacking. Thus, a global meta‐analysis was conducted to determine the effects of NT on soil pH and to identify the influential factors and possible consequences based on the analysis of 114 publications. When comparing tillage practices, the results indicated an overall significant decrease by 1.33 ± 0.28% in soil pH under NT than that under conventional tillage (p < .05). Soil texture, NT duration, mean annual temperature (MAT), and initial soil pH are the critical factors affecting soil pH under NT. Specifically, with significant variations among subgroups, when compared to conventional tillage, the soil under NT had lower relative changes in soil pH observed on clay loam soil (−2.44%), long‐term implementation (−2.11% for more than 15 years), medium MAT (−1.87% in the range of 8–16℃), neutral soil pH (−2.28% for 6.5 < initial soil pH < 7.5), mean annual precipitation (−1.95% in the range of 600–1200 mm), in topsoil layers (−2.03% for 0–20 cm), with crop rotation (−1.98%), N fertilizer input (the same for NT and conventional tillage) of 100–200 kg N ha−1 (−1.83%), or crop residue retention (−1.52%). Changes in organic matter decomposition under undisturbed soil and with crop residue retention might lead to a higher concentration of H+ and lower of basic cations (i.e., calcium, magnesium, and potassium), which decrease the soil pH, and consequently, impact nutrient dynamics (i.e., soil phosphorus) in the surface layer under NT. Furthermore, soil acidification may be aggravated by NT within site‐specific conditions and improper fertilizer and crop residue management and consequently leading to adverse effects on soil nutrient availability. Thus, there is a need to identify strategies to ameliorate soil acidification under NT to minimize the adverse consequences.
A global meta‐analysis was conducted to indicate that NT could significantly reduce the soil pH. Variations in the soil pH among different regions and/or pedoclimatic conditions were observed. Combined with the model selection analysis, four essential drivers were confirmed. A higher concentration of H+ and lower basic cations may enhance the risk of NT to acidify the soil. Consequently, nitrogen and other soil nutrients were impacted, especially in the surface soil. Potential strategies to ameliorate soil acidification maybe the optimal combination of NT with site‐specific fertilization and crop residue management practices.
Microwave dielectric ceramics are considered to be one of the key materials for dielectric resonators (DR) and have very broad application prospects in the fifth generation (5G) mobile communication ...system. Here we have prepared high‐quality factor Y3Al5O12 (YAG) transparent dielectric ceramics using high‐purity α‐Al2O3 and Y2O3 powders by cold isostatic pressing of the vacuum sintered with tungsten meshes as the heating elements. Optimum relative permittivity (εr) ~10.53, quality factor Q × f (Q = 1/dielectric loss, f = resonant frequency) ~95, 270 GHz (at =7.37 GHz), and temperature coefficient of resonant frequency (TCF) ~ −51.7 ppm °C−1 were obtained at a sintering temperature of 1780°C for 12 h. For the first time, YAG transparent ceramic dielectric resonator antenna (DRA) is designed as a dominant TE111y mode and a higher‐order TE113y mode using the aperture coupling feeding configuration excitation. The proposed transparent dielectric ceramic DRA can provide a broad impedance bandwidth of 4.193 GHz (ranging from 21.90 to 26.09 GHz) for S11 < −10 dB, radiation efficiency of 92.1%, and compact DR unit. The proposed DRA can be used potentially as a 5G millimeter (mm)‐wave multiple‐input‐multiple‐output (MIMO) antenna unit.
YAG transparent dielectric ceramics were fabricated by cold isostatic pressing (CIP) of the vacuum sintered with tungsten meshes as the heating elements. Since the YAG transparent ceramic have a suitable relative permittivity, low dielectric loss and excellent optical properties, making it a promising material for high quality factor YAG transparent dielectric ceramic DRA for 5G mm‐wave application for the first time. The characteristics of the proposed DRA indicate that it is an excellent candidate for 5G mm‐wave MIMO antenna application.
Graphene quantum dots (GQDs) have attracted tremendous research interest due to the unique properties associated with both graphene and quantum dots. Here, a new application of GQDs as ideal ...electrode materials for supercapacitors is reported. To this end, a GQDs//GQDs symmetric micro‐supercapacitor is prepared using a simple electro‐deposition approach, and its electrochemical properties in aqueous electrolyte and ionic liquid electrolyte are systematically investigated. The results show that the as‐made GQDs micro‐supercapacitor has superior rate capability up to 1000 V s−1, excellent power response with very short relaxation time constant (τ0 = 103.6 μs in aqueous electrolyte and τ0 = 53.8 μs in ionic liquid electrolyte), and excellent cycle stability. Additionally, another GQDs//MnO2 asymmetric supercapacitor is also built using MnO2 nanoneedles as the positive electrode and GQDs as the negative electrode in aqueous electrolyte. Its specific capacitance and energy density are both two times higher than those of GQDs//GQDs symmetric micro‐supercapacitor in the same electrolyte. The results presented here may pave the way for a new promising application of GQDs in micropower suppliers and microenergy storage devices.
Graphene quantum dots (GQDs)‐based micro‐supercapacitors are prepared using a simple eletrodeposition approach and their electrochemical properties in aqueous and ionic liquid electrolytes are studied. The GQDs‐based micro‐supercapacitors exhibit superior rate capability, high power response capability, and excellent cyclic stability
Coronavirus disease 2019 is a newly emerging infectious disease currently spreading across the world. It is caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 ...(SARS-CoV-2). The spike (S) protein of SARS-CoV-2, which plays a key role in the receptor recognition and cell membrane fusion process, is composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain that recognizes and binds to the host receptor angiotensin-converting enzyme 2, while the S2 subunit mediates viral cell membrane fusion by forming a six-helical bundle via the two-heptad repeat domain. In this review, we highlight recent research advance in the structure, function and development of antivirus drugs targeting the S protein.
Most organic polymeric materials have high flammability, for which the large amounts of smoke, toxic gases, heat, and melt drips produced during their burning cause immeasurable damages to human life ...and property every year. Despite some desirable results having been achieved by conventional flame‐retardant methods, their application is encountering more and more difficulties with the ever‐increasing high flame‐retardant requirements such as high flame‐retardant efficiency, great persistence, low release of heat, smoke, and toxic gases, and more importantly not deteriorating or even enhancing the overall properties of polymers. Under such condition, some advanced flame‐retardant methods have been developed in the past years based on “all‐in‐one” intumescence, nanotechnology, in situ reinforcement, intrinsic char formation, plasma treatment, biomimetic coatings, etc., which have provided potential solutions to the dilemma of conventional flame‐retardant methods. This review briefly outlines the development, application, and problems of conventional flame‐retardant methods, including bulk‐additive, bulk‐copolymerization, and surface treatment, and focuses on the raise, development, and potential application of advanced flame‐retardant methods. The future development of flame‐retardant methods is further discussed.
Flame‐retardant methods for polymeric materials are reviewed with particular focus on advanced flame‐retardant methods developed in recent years. Both the advantages and drawbacks of these methods are discussed, and prospects for the future development of flame‐retardant methods are presented. It is hoped that this review will guide the development of flame‐retardant polymeric materials.
Regulating the tumor microenvironment (TME) has been a promising strategy to improve antitumor therapy. Here, a red blood cell membrane (mRBC)‐camouflaged hollow MnO2 (HMnO2) catalytic nanosystem ...embedded with lactate oxidase (LOX) and a glycolysis inhibitor (denoted as PMLR) is constructed for intra/extracellular lactic acid exhaustion as well as synergistic metabolic therapy and immunotherapy of tumor. Benefiting from the long‐circulation property of the mRBC, the nanosystem can gradually accumulate in a tumor site through the enhanced permeability and retention (EPR) effect. The extracellular nanosystem consumes lactic acid in the TME by catalyzing its oxidation reaction via LOX. Meanwhile, the intracellular nanosystem releases the glycolysis inhibitor to cut off the source of lactic acid, as well as achieve antitumor metabolic therapy through the blockade of the adenosine triphosphate (ATP) supply. Both the extracellular and intracellular processes can be sensitized by O2, which can be produced during the decomposition of endogenous H2O2 catalyzed by the PMLR nanosystem. The results show that the PMLR nanosystem can ceaselessly remove lactic acid, and then lead to an immunocompetent TME. Moreover, this TME regulation strategy can effectively improve the antitumor effect of anti‐PDL1 therapy without the employment of any immune agonists to avoid the autoimmunity.
A strategy based on intra/extracellular lactic acid exhaustion is reported to achieve synergistic metabolic therapy and immunotherapy of tumors. This strategy is performed by a cascade catalytic nanosystem (PMLR) that integrates a hollow MnO2 nanocarrier with lactate oxidase and a glycolysis inhibitor.
Dysfunction of the circadian rhythm is one of most common nonmotor symptoms in Parkinson's disease (PD), but the molecular role of the circadian rhythm in PD is unclear. We here showed that ...inactivation of brain and muscle ARNT‐like 1 (BMAL1) in 1‐methyl‐4‐phenyl‐1,2,4,5‐tetrahydropyridine (MPTP)‐treated mice resulted in obvious motor functional deficit, loss of dopaminergic neurons (DANs) in the substantia nigra pars compacta (SNpc), decrease of dopamine (DA) transmitter, and increased activation of microglia and astrocytes in the striatum. Time on the rotarod or calorie consumption, and food and water intake were reduced in the Bmal1−/− mice after MPTP treatment, suggesting that absence of Bmal1 may exacerbate circadian and PD motor function. We observed a significant reduction of DANs (~35%) in the SNpc, the tyrosine hydroxylase protein level in the striatum (~60%), the DA (~22%), and 3,4‐dihydroxyphenylacetic acid content (~29%), respectively, in MPTP‐treated Bmal1−/− mice. Loss of Bmal1 aggravated the inflammatory reaction both in vivo and in vitro. These findings suggest that BMAL1 may play an essential role in the survival of DANs and maintain normal function of the DA signaling pathway via regulating microglia‐mediated neuroinflammation in the brain.
Droplet-based microfluidics has emerged as a powerful platform for high-throughput and low-volume analysis and screening. At present, droplet-based microfluidics is transitioning from the ...proof-of-concept stage to real-world applications. During this process, analytical detection techniques play indispensable roles for successfully implementing droplet-based chemical or biological assays. In this review, we provide an overview of recent developments in analytical techniques for droplet analysis and elucidate the advantages and limitations of each technique. We cover the majority of technology categories, including optical detection, electrical detection, mass spectrometry, and nuclear magnetic resonance spectroscopy. Additionally, we highlight new research areas that have been enabled by these technical advances. Finally, we provide perspectives on both future technological directions and potential enabling applications.
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•Analytical detection techniques are key considerations in droplet-based assay.•We review the advances of analytical techniques and applications from 2013 to 2019.•We underline the progress of optical detection, electrical detection, MS, and NMR.•We provide perspectives on future technical directions and potential applications.
Extreme hypoxia of tumors represents the most notable barrier against the advance of tumor treatments. Inspired by the biological nature of red blood cells (RBCs) as the primary oxygen supplier in ...mammals, an aggressive man‐made RBC (AmmRBC) is created to combat the hypoxia‐mediated resistance of tumors to photodynamic therapy (PDT). Specifically, the complex formed between hemoglobin and enzyme‐mimicking polydopamine, and polydopamine‐carried photosensitizer is encapsulated inside the biovesicle that is engineered from the recombined RBC membranes. The mean corpuscular hemoglobin of AmmRBCs reaches about tenfold as high as that of natural RBCs. Owing to the same origin of outer membranes, AmmRBCs share excellent biocompatibility with parent RBCs. The introduced polydopamine plays the role of the antioxidative enzymes existing inside RBCs to effectively prevent the oxygen‐carrying hemoglobin from the oxidation damage during the circulation. This biomimetic engineering can accumulate in tumors, permit in situ efficient oxygen supply, and impose strong PDT efficacy toward the extremely hypoxic tumor with complete tumor elimination. The man‐made pseudo‐RBC shows potentials as a universal oxygen‐self‐supplied platform to sensitize hypoxia‐limited tumor treatment means, including but not limited to PDT. Meanwhile, this study offers ideas to the production of artificial substitutes of packed RBCs for clinical blood transfusion.
Aggressive man‐made pseudo‐red blood cells (AmmRBCs) are prepared for self‐oxygen‐supplied photodynamic therapy (PDT) toward tumors. AmmRBCs can accumulate in tumors and exhibit high efficacy to combat hypoxia‐induced resistance of tumors to PDT, leading to complete tumor elimination.
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