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A novel N-doped graphene-like carbon nanosheets (CNs) and carbon nanotubes (CNTs)-encapsulated Co-Co3O4 nanoparticles (NPs) (CN@Co-Co3O4/CNTs) were synthesized successfully by a simple hydrothermal and annealing method with graphite carbon nitride (g-C3N4) as self-template. By annealing Co2+/g-C3N4 under N2 atmosphere, g-C3N4 was transformed into CN/CNTs, and Co2+ was reduced into CoNPs which were embedded in CNs. Further annealing in air, a shell of Co3O4 was formed around CoNPs. The amount of CNs, CNTs, and CoNPs can be adjusted by changing the ratio of Co2+ in Co2+/g-C3N4. The graphene-like CNs provided a large number of active sites and a large specific surface area for loading lots of small CoNPs uniformly. The CNTs with a diameter of 100 nm could not only improve the conductivity but also provide a buffer space for the aggregation and volume expansion of Co3O4. CNTs also enlarged the interlayer distance of CNs, which prevented the re-stacking of CNs and provided great convince for the intercalation and de-intercalation of Li+. When applied for anode material of lithium-ion batteries, CN@Co-Co3O4/CNTs exhibited a high discharge capacity of 460.0 mAh g−1 at 5000 mA g−1 after 300 cycles with a Coulombic efficiency of 98% and excellent higher-rate capacity (401.0 mAh g−1 at 2000 mA g−1 and 329.0 mAh g−1 at 5000 mA g−1).

Bioconversion (e.g. anaerobic fermentation and compost) is the common recycling method of waste activated sludge (WAS) and its hydrolysis, as the rate-limiting step of fermentation, could be accelerated by protease. However, the commercial protease was unstable in a sludge environment, which increased the cost. An endogenous alkaline protease stable in sludge environment was screened in this study and its suitability for treating the sludge was analyzed. The optimal production medium was determined by Response Surface Methodology as starch 20 g/L, KH2PO4 4 g/L, MgSO4·7H2O 1 g/L, sodium carboxy-methyl-cellulose 4 g/L, casein 4 g/L and initial pH 11.3, which elevated the yield of protease by up to 15 times (713.46 U/mL) compared with the basal medium. The obtained protease was active and stable at 35 °C–50 °C and pH 7.0–11.0. Furthermore, it was highly tolerant to sludge environment and maintained high efficiency of sludge hydrolysis for a long time. Thus, the obtained protease significantly hydrolyzed WAS and improved its bioavailability. Overall, this work provided a new insight for enzymatic treatment of WAS by isolating the endogenous and stable protease in a sludge environment, which would promote the resource utilization of WAS by further bioconversion. HIGHLIGHTS A novel protease-producing bacterium was isolated from the sludge.; The screened protease was highly tolerant to the sludge environment.; Treatment of the sludge by the screened protease elevated its bioavailability.; The screened protease was a promising biocatalyst for sludge treatment.

A mild method for accessing diazo compounds via aerobic oxidation of hydrazones is described. This catalytic transformation employs a Cu(OAc)2/pyridine catalyst and molecular oxygen from ambient ai...

Uranium is a common radionuclide contaminant in groundwater. Recovery of uranium from uranium-containing water can achieve the dual purposes of uranium remediation and uranium resource utilization. However, very few studies have successfully achieved this task. In this study, we developed a microbial fuel cell (MFC) system with a titanium dioxide nanotube array (TNTA) cathode, which could efficiently remove (over 95%) and recover (over 97%) uranium from uranium-containing water. Results demonstrated that the removal of U(VI) in the MFC was through an adsorption–reduction–deposition mechanism. U(VI) was adsorbed by the TNTA cathode, and the adsorbed U(VI) was further electroreduced to U(IV)O2 and deposited on the surface of the TNTA cathode. The reduction of adsorbed U(VI) initiated re-equilibration of the desorption reaction of adsorbed U(VI) and induced re-adsorption of U(VI). The re-adsorbed U(VI) could be further electroreduced to U(IV)O2, which resulted in the continuous removal of U(VI). Finally, 2.95 μmol U(VI) was reduced and deposited as U(IV)O2 on the surface of the TNTAs (1476.22 μmol m−2) without observing capacity saturation. Moreover, the deposited U(IV)O2 can be easily separated from the TNTA cathode with dilute nitric acid, and the TNTA cathode can be used repeatedly with stable performance.

The fabrication, by an electrochemical process, of a new battery-type electrode material, is presented. Such materials are fabricated by direct current electrodeposition of Ni(OH)2 on lamellar Ni3Si. Microstructure and morphology of Ni(OH)2/Ni3Si electrodes were characterised. Cyclic voltammetry and galvanostatic charge–discharge results revealed that they are battery-type electrodes. Increasing deposition time or decreasing discharge current can significantly increase the areal capacity. The areal capacity of Ni(OH)2/Ni3Si-20 with a discharge current of 20 mA is only 2.8% of that with 1 mA. However, the increasing deposition time will reduce the cyclic stability of the electrodes. The initial areal capacity of Ni(OH)2/Ni3Si-20 is twice that of Ni(OH)2/Ni3Si-10 with a discharge current of 10 mA, but after 1000 cycles, it can only maintain 59.3% of the initial value. This Letter is expected to provide a powerful reference and guidance for the preparation of electrodes with large areal capacity and cycle stability.

Herein, a new activated porous carbon (APC) was proposed by carbonizing waste biomass of pinecone which could be obtained in large quantities and subsequently activation of zinc chloride. Then small Co3O4 nanoparticles were loaded on the surface and holes of APC to prepare the final Co3O4/APC nanocomposites. The as-prepared APC had a lotus root-like and layered porous structure with a large number of mesopores and micropores. The APC reduced the agglomeration of small Co3O4 particles which were uniformly anchored on the surface of APC. When applied for the anode of lithium-ion batteries, the Co3O4/APC nanocomposites had a reversible capacity of 625 mAh g−1 after 200 cycles at the current density of 500 mA g−1. The Co3O4/APC nanocomposites also had a good rate performance. Above all, this work could transform waste biomass into sustainable resource, and the raw materials were easy to obtain in large quantities.

N-doped honeycomb-like carbon networks (N–HCN) loaded with ultra-fine Fe2O3 nanoparticles (Fe2O3/N–HCN) are proposed as anode materials for lithium-ion batteries (LIBs). The Fe2O3/N–HCN nanocomposites are prepared by freeze-drying of glucose-Fe(NO3)3 solution, following by grinding it with urea, and finally annealing treatment. The N–HCN with dozen micrometer-sized macropores is composed of carbon nanosheets with a thickness of about 33 nm. A large number of 2–7 nm-sized ultra-fine Fe2O3 nanoparticles with an average size of 4.4 nm are uniformly arrayed on the wall of N–HCN. The Fe2O3/N–HCN nanocomposites exhibit good performances as anode materials for LIBs. After 500 cycles under a large current density of 5 A g−1, the Fe2O3/N–HCN nanocomposites still show a reversible capacity of 408 mAh g−1. The good performance can be ascribed to the uniformly dispersed ultra-fine Fe2O3 nanoparticles and unique honeycomb-like structure of N–HCN which provides a continuous conductive network to greatly promote the rapid transfer of ions and electrons, and effectively alleviate the volume fluctuation effect of Fe2O3 during charging and discharging. More importantly, the cheap and environmentally friendly glucose as raw materials provides possibility for green energy applications.

Herein we demonstrate a packed bed flow reactor capable of achieving highly regio- and stereoselective C-H functionalization reactions using a newly developed Rh2 (S-2-Cl-5-CF3 TPCP)4 catalyst. To optimize the immobilized dirhodium catalyst employed in the flow reactor, we systematically study both (i) the effects of ligand immobilization position, demonstrating the critical factor that the catalyst-support attachment location can have on the catalyst performance, and (ii) silica support mesopore length, demonstrating that decreasing diffusional limitations leads to increased accessibility of the active site and higher catalyst turnover frequency. We employ the immobilized dirhodium catalyst in a simple packed bed flow reactor achieving comparable yields and levels of enantioselectivity to the homogeneous catalyst employed in batch and maintain this performance over ten catalyst recycles.

Lamellar Ni3Si was electrochemically prepared. Its structure and microhardness were controlled by the directional solidification growth rate and selective corrosion time. It exhibits strong corrosion resistance to acid and alkali. The mass of Ni3Si stationed in 50 wt pct H2SO4 and 25 wt pct NaOH after 200 hours remained 94.4 and 98.8 pct, respectively. The prepared Ni(OH)2/Ni3Si electrode using lamellar Ni3Si compound as a matrix delivered a higher areal capacity and cycle stability than the Ni(OH)2 electrode.

Submarine pipeline was widely used to transport oil and gas in offshore petroleum exploitation. In practice, deep-water pipeline experiences several times of maintenance every year. This periodic o...

Tyrosinase is the key enzyme in melanin biosynthesis and inherently involves both monophenolase activity and diphenolase activity. A continuous fluorometric assay method was developed for the first time to directly monitor the real monophenolase activity without the interference of diphenolase reactions through exclusively quenching the native fluorescence of DOPA by borate. Complexation with borate at pH 8.0 allowed for selective quantitation of tyrosine in a binary mixture of tyrosine and DOPA at 335 nm. The time course for consumption of tyrosine was established to measure the initial velocity by recording the tyrosine fluorescence intensity at discrete intervals. The assay worked in the monophenolase activity range from 0.13 to 2.01 U mL-1 with the limit of detection (LOD) of 0.10 U mL-1. The assay method exhibited a promising prospect in application in kinetics of monophenolase and high throughput screening for monophenolase inhibitors.

Chitin-derived hydrogels are commonly used in bone regeneration because of their high cell compatibility; however, their poor mechanical properties and little knowledge of the interaction between the materials and host cells have limited their practical application. Methods: To evaluate osteoinductivity and enhance the mechanical properties of a newly synthesized thermosensitive hydroxypropyl chitin hydrogel (HPCH), a mesenchymal stem cell (MSC)-encapsulated HPCH was infused into a three-dimensional-printed poly (e-caprolactone) (PCL)/ nano-hydroxyapatite (nHA) scaffold to form a hybrid scaffold. The mechanical properties and cell compatibility of the scaffold were tested. The interaction between macrophages and scaffold for angiogenesis and osteogenesis were explored in vitro and in vivo. Results: The hybrid scaffold showed improved mechanical properties and high cell viability. When MSCs were encapsulated in HPCH, osteo-differentiation was promoted properly via endochondral ossification. The co-culture experiments showed that the hybrid scaffold facilitated growth factor secretion from macrophages, thus promoting vascularization and osteoinduction. The Transwell culture proved that MSCs modulated the inflammatory response of HPCH. Additionally, subcutaneous implantation of MSC-encapsulated HPCH confirmed M2 activation. In situ evaluation of calvarial defects confirmed that the repair was optimal in the MSC-loaded HPCH + PCL/nHA group. Conclusions: PCL/nHA + HPCH hybrid scaffolds effectively promoted vascularization and osteoinduction via osteogenesis promotion and immunomodulation, which suggests promising applications for bone regeneration.

Recent developments in controlled C–H functionalization transformations continue to inspire new retrosynthetic disconnections. One tactic in C–H functionalization is the intermolecular C–H insertion reaction of rhodium bound carbenes. These intermediates can undergo highly selective transformations through the modulation of the ligand framework of the rhodium catalyst. This work describes our continued efforts towards differentiating C–H bonds in the same molecule by judicious catalyst choice. Substituted cyclobutanes which exist as a mixture of interconverting conformers and possess neighboring C–H bonds within a highly strained framework are the targets herein for challenging the current suite of catalysts. While most C–H functionalization tactics focus on generating 1,2-disubstituted cyclobutanes via substrate-controlled directing group methods, the regiodivergent methods in this paper provide access to chiral 1,1-disubstituted and cis -1,3-disubstituted cyclobutanes simply by changing the catalyst identity, thus permitting entry to novel chemical space.

Removal of uranium from groundwater is of great significance as compared to in situ bioimmobilization technology. In this study, a novel direct electro-reductive method has been developed to efficiently remove and recover uranium from carbonate-containing groundwater, where U(VI)O

Water electrolysis was recognized as an effective method for new energy sources. In this work, an effective FexNiyOOH/ESS with high surface area and good catalytic activity was prepared for water electrolysis. Its morphologies at different ratio of Fe/Ni atoms were diverse, such as flower ball, flake, and block, etc. Test results showed that at 10 mA cm−2 and 300 mA cm−2, the hydrogen evolution overpotentials of Fe1.5Ni0.5OOH/ESS were 172 mV and 258 mV. The oxygen evolution overpotentials of Fe0.2Ni1.8OOH/ESS were 208 mV and 308 mV at 10 mA cm−2 and 600 mA cm−2. During the 136-h stability test, the oxygen evolution activity of Fe0.2Ni1.8OOH/ESS was basically unchanged. The Fe1.5Ni0.5OOH//Fe0.2Ni1.8OOH in alkaline conditions presented good performance for water electrolysis. Water electrolysis experiment was carried out at 1.58 V, and the current density reached to 10 mA cm−2. FexNiyOOH/ESS exhibited higher electrocatalytic activity and superior stability at high current density.

The utilization of CO2 for enhancing oil recovery is an environmentally friendly way to dispose the industrial CO2 emissions. CO2 utilization ratio is defined as the volume ratio of produced oil to injected CO2. CO2 huff and puff technology can further improve oil recovery in high water cut reservoirs. However, as the huff and puff cycle increase, gas channeling is easy to happen and the utilization ratio of CO2 is reduced. Organic fiber composite gel is an effective plugging agent for gas channel. The major objective of this paper is to study the mechanisms of increasing CO2 utilization by injecting organic composite gel as the plugging agent. A large scale (40 cm*40 cm*3 cm) natural rock model with grooves is used to simulate the experimental conditions such as channeling channel and horizontal well. Two groups of experiments of direct CO2 huff and plugging agent assisted CO2 huff and puff were conducted. By comparing the pressure changes during the experiments, the mechanism of blocking the channel, balancing the CO2 displacement front and improving the utilization ratio of CO2 were analyzed. The experimental process was fitted by reservoir numerical simulation, and the remaining oil distribution, plugging agent distribution and CO2 distribution in CO2 huff and puff under different conditions were further demonstrated. Results show that compared with direct CO2 stimulation, the distribution of remaining oil saturation and reservoir pressure become more uniform and the utilization ratio of CO2 is greatly increased after injecting organic fiber composite gel. It is mainly due to the fact that the injected plugging agents flow preferentially into high water saturation region along the high permeability channels. Then, they can generate the organic fiber composite gel and remain in the channeling paths. As a result, the following injected CO2 will be forced to flow towards oil-rich regions radially and uniformly. Thereby, more CO2 can contact and react with the in-situ oil, resulting much higher oil recovery. In other words, the utilization ratio of CO2 is greatly improved. Taking Jidong oilfield as an example, it has been injected 19.2 × 104 t CO2 with the total oil production by 21.1 × 104 t. The utilization ratio of CO2 is calculated as high as 1.09. The observations of this study provide the theoretical basis for future application of organic fiber composite gel before CO2 flooding in the water channeling reservoirs.

For the low-concentration oily micro-polluted water formed by the leakage of refined oil products, an unexpensive and high-efficiency magnetic enhanced flocculation method was introduced in this study. First, the performance of magnetic flocculation(MF) to remove oily contaminants was discussed. The results indicated that it achieved more than 95% removal in only 1min with 50mg/L-Polyaluminum chloride(PAC), 50mg/L-Fe3O4 and10mg/L- Polyacrylamide (PAM). The novel indexs Rδand Si were proposed to evaluate the oil removal with UV-Abs in-situ method. According to the adsorption kinetics of oil contaminants, the adsorption kinetics changed from pseudo-first-order to pseudo-second-order kinetics after the addition of Fe3O4 on the basis of conventional coagulation (CF). It was transformed into intraparticle diffusion kinetics when the PAM continued to be added. Combined with the Fe-O-Al bond in the FTIR spectrum of flocs, the main mechanism of MF is enhanced charge neutralization and hydrogen bond adsorption. In addition, it was shown that satisfactory oil removal after recover, which indicated the great potential of a sustainable way by reusing low-cost magnetic seeds.

A nonmagnetic metal droplet with dynamic interfaces under a time-varying magnetic field was considered. Considering that the thermal effect of the magnetic field and the droplet evaporation were disregarded, we obtained the magnetically augmented Young–Laplace equation theoretically according to the normal stress balance principles. The droplet contact angle was further determined according to the droplet volume conservation. According to the curvature and contact angle, the droplet profile was mathematically determined. Results showed that a downward magnetic force caused droplet contraction and an upward force caused expansion. The increase in surface tension hindered the droplet spreading without affecting the change trend of droplet shape parameters. The increase in angular frequency (ω) decreased the variation amplitude of the droplet curvature and contact angle, and the increase in damping factor (τ) slowed down the decay of the droplet curvature and contact angle.

A kind of porous carbon with low cost and abundance in nature derived from loofah sponge (LS) was prepared and applied as three-dimensional (3D) conductive network to support flower-like CoO for lithium-ion batteries' (LIBs) anode. LS, as a natural biomass, was rich in nitrogen source and also had abundantly porous structures. Therefore, the formation of porous LS carbon (LSC) with excellent electrical conductivity and high specific areas made it possible to replace relative expensive graphene or carbon nanotubes. When it was used as the supporting matrix to load the flower-like CoO, 3D conductive carbon network and porous structure could not only improve the electron transport and area of contact with the electrolyte, but also buffer general problem of cracking or pulverization caused by the volume stress of CoO. Finally, the obtained flower-like CoO/LSC nanocomposites exhibited a high capacity of 781 mAh g−1 at 200 mA g−1 after 150 discharging/charging cycles and an outstanding rate capability, which was far better than that of pure LSC, CoO and commercial graphite. The good performance showed that LS might be used widely in LIBs as an effective supporting conductive carbon material due to its accessibility and low cost. It also provided a thinking approach to make good use of many natural resources for energy storage.

As an important aspect of epigenetics, DNA methylation has been proven to be suitable for forensic DNA analysis. By detecting changes in DNA methylation, it is desirable to construct a model of age patterns associated with it to infer the age of the individual. The hTERT gene methylation is closely related to tumors, but there are few reports on the relationship between hTERT gene promoter methylation and age. In this study, we utilized the methylation-specific polymerase chain reaction and real-time PCR (relative quantification and absolute quantification) approach to explore the connection between hTERT DNA methylation and age prediction. We fit three models for age prediction based on methylation assay for 90 blood samples from donors aged 1–79 years old. Among them, the model of absolute quantification of real-time enabled the age prediction with R2 = 0.9634. We verified the linear regression model with a validation set of 30 blood samples where prediction average error was 4.29 years. Generally, this reliable method improves the DNA methylation analysis of forensic samples.

Spatio-temporal patterns of drought from 1961 to 2013 over the Beijing-Tianjin-Hebei (BTH) region of China were analyzed using the Palmer Drought Severity index (PDSI) based on 21 meteorological stations. Overall, changes in the mean-state of drought detected in recent decades were due to decreases in precipitation and potential evapotranspiration. The Empirical Orthogonal Functions (EOF) method was used to decompose drought into spatio-temporal patterns, and the first two EOF modes were analyzed. According to the first leading EOF mode (48.5%), the temporal variability (Principal Components, PC1) was highly positively correlated with annual series of PDSI (r=+0.99). The variance decomposition method was further applied to explain the inter-decadal temporal and spatial variations of drought relative to the total variation. We find that 90% of total variance was explained by time variance, and both total and time variance dramatically decreased from 1982 to 2013. The total variance was consistent with extreme climate events at the inter-decadal scale (r=0.71, p

Climate change in mean-state or variability could lead to more/less frequency of extreme drought. In this study, we developed a new framework for decomposing the contributing factors of changes in future extreme drought frequency in China in accordance to the Palmer Drought Severity Index (PDSI). We performed a series of numerical experiments to ensure that the sensitivity of trend and variability in individual climatic variables can be distinguished. In addition, an extreme drought rate with warming (EDRW, unit: %·K−1) is defined to quantify the relative change in extreme drought frequency per Kelvin. Overall, the EDRW will increase dramatically by an average of 27.71%·K−1. The ascended EDRW are attributed to increases in temperature (+56.90%·K−1), net radiation (14.80%·K−1) and precipitation variability (+8.23%·K−1); a decrease in relative humidity (+4.61%·K−1), but is partly offset by an increase in precipitation (i.e., “wetting”, −60.12%·K−1). A smaller increase in the frequency of extreme droughts is found in high-latitude regions due to their enhanced sensitivity to “wetting”.

The new persistent organic pollutant (POP), 1,2,5,6,9,10-hexabromocyclododecane (HBCD), has been widely detected in various environmental media and proved to be biotoxic. However, the research on catalytic degradation of HBCD is in its infancy. Herein, we examined the degradation of α-HBCD, β-HBCD and γ-HBCD, over Fe3O4 micro/nanomaterial at 200 °C. The pseudo-first-order kinetic rate constants were in the range of 0.04–0.15 min−1, with half-life values of 5–19 min. γ-HBCD is slightly less stable than β-HBCD, but both of them readily convert into α-HBCD, as consistent with the Gibbs free energies of isomers themselves. The four products containing pentabromocyclododecene, two isomers of tetrabromocyclododecene and 1,5,9-cyclododecatriene were detected by conventional GC–MS. Interestingly, a high-throughput non-target product detection were performed by ESI-FT-ICR-MS, where up to 59 types of intermediate products were determined. It is tentatively proposed that different types of bromine-removed products (C12H17Br5, C12H18Br4, C12H18, C12H19Br5, C12H24 and C12H19Br5O) and cyclododecane ring-opened products (C12H19Br7, C12H20Br6O and C12H20Br6) form via elimination reaction, nucleophilic substitution, hydrodebromination and addition reaction. Besides, most of the products that were detected contained oxygen. The average carbon oxidation state ( OS c ¯ ) of the products indicate that the oxidation reaction is the dominant reaction type. Deep oxidation products, such as small molecular organic acids (formic, acetic, propionic, and butyric acids) and gas-phase oxidation products (CO2 and CO) were further detected by ion chromatography and GC-FID, respectively. This study might provide an alternative technique for the low-cost treatment of HBCD waste.

A novel hollow Co-Co3O4 coated with carbon nanotubes (CNTs) nanostructure was designed. Here, zeolite imidazolate framework-67 cubes were used as sacrificial template and carbonized under H2/Ar atmosphere along with in-situ growth of CNTs to form Co nanostructures@CNTs. Then the Co nanostructures@CNTs was treated by thermal-oxidation under air to further construct hollow Co-Co3O4@CNTs. The obtained hollow Co-Co3O4@CNTs was characterized by scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption isotherms, X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical techniques. It was found that the hollow Co-Co3O4@CNTs cubes were wrapped by lots of CNTs. As it was used as anode materials for lithium ion batteries (LIBs), after cycling 200 cycles at 0.2 A g−1, the reversible capacity was still kept at 806.7 mA h g−1. Excellent cycle stability and Li+ storage capacity originated from the hollow nanostructures and the encapsulation of CNTs around hollow Co-Co3O4 cubes to buffer the volume change of Co3O4 and improve the electrical conductivity. Meanwhile, the increased specific surface area could effectively improve the storage of Li+. Therefore, the hollow Co-Co3O4@CNTs might have potential application in LIBs.

Based on the classical Nix-Gao model of indentation size effect (ISE), a new model incorporating the role of elastic deformation is proposed for modeling ISE at indentation depths below 100 nm. We show that, while elastic deformation is generally not associated with the generation of geometrically necessary dislocations (GNDs), neglecting it can lead to severe overestimation of both the nanoindentation hardness and GND density at small indentation depths, particularly below 100 nm, and the reverse ISE is also described. In this sense, elastic deformation can play an essential role in estimating nanoindentation hardness at small indentation depths. It is shown that our model predictions are in good agreement with experimental results on nanoindentation of single Cu and MgO crystals. A similar model applied to ISE in ion-irradiated metallic materials, where the irradiation hardening effect and ISE are successfully separated, enables analysis of irradiation hardening in ion-irradiated metallic materials without the interference of ISE.

A new kind of bifunctional magnetic-fluorescent nanoparticles (NPs) with abundant carboxyls on the surface has been prepared by covalently combining glutathiose (GSH)-modified CdTe quantum dots (QDs) with Fe3O4@SiO2 NPs. The silica-coated Fe3O4 NPs were functionalized with amino groups by (3-aminopropyl)triethoxysilane to provide Fe3O4@SiO2-NH2 NPs, which was then chemically conjugated with GSH-modified CdTe QDs to form bifunctional magnetic-fluorescent NPs, Fe3O4@SiO2-NH-CO-CdTe-QDs NPs. The properties and morphologies of Fe3O4@SiO2-NH-CO-CdTe-QDs NPs were investigated by FTIR, X-ray diffraction, transmission electron microscopy (TEM), absorption and fluorescence spectroscopy and vibrating sample magnetometry. TEM images display that Fe3O4@SiO2-NH-CO-CdTe-QDs NPs possess spherical core-shell structure with a uniform size about 50 nm. The bifunctional NPs were found to exhibit good magnetic and strong fluorescent properties favorable for their application in the detection of latent fingerprints. Furthermore, the carboxyls on the surface of NPs have good absorptions with water in air and the residues of fingerprints so as to not only avoid dust flying to protect the health of operators, but also improve the efficiency of detection.

Three-dimensional (3D) carbon foams (CF) surrounded by carbon nanotubes (CNTs) and Co-Co3O4 nanoparticles (NPs) (CF@Co-Co3O4/CNT) nanocomposites were prepared by a two-step method for stable lithium-ion batteries (LIBs). The low-cost melamine foams pre-soaked in cobalt nitrate solution were firstly carbonized under nitrogen atmosphere to form 3D CF surrounded by a large number of CNTs and Co NPs (CF@Co/CNT). Subsequently, the CF@Co/CNT was transformed into CF@Co-Co3O4/CNT nanocomposites by calcination in air. Here, Co NPs, CNT and 3D CF all improved the electrical conductivity of CF@Co-Co3O4/CNT nanocomposites. In addition, a large number of uniformly-dispersed small Co3O4 NPs effectively increased Li+ storage capacity of nanocomposites. At the same time, the 3D macroporous carbon frameworks surrounded by CNT could also relieve the volume deformation of Co3O4 NPs to some extent. When it was employed as anode materials for LIBs, CF@Co-Co3O4/CNT nanocomposites exhibited the stable reversible capacities of about 500 mAh g−1 at 0.5 A g−1, larger than that of commercial graphite and some other Co-based materials. The two-step preparation method was simple and convenient for large-scale production.

Remote sensing based vegetation index provides a practical method for the monitoring of vegetation dynamics at regional and global scales. Here, using a long-term remotely sensed normalized difference vegetation index (NDVI) dataset, we quantified the vegetation changes in the Loess Plateau (LP) over the last three decades (1982–2015), which includes the period before the Chinese“Grain for Green Program”(GGP) was launched (1982–1999), and the period after the GGP (1999–2015). The correlations between the NDVI and four climate related variables, i.e., precipitation, temperature, root-soil moisture (RSM), and a drought proxy-standardized evapotranspiration deficit index (SEDI), were also examined. The results indicated that, (i) the GGP strongly changed the vegetation in the LP. The growing-season mean NDVI (GSM-NDVI) and the annual mean NDVI (AM-NDVI) decreased slightly before the GGP launched in 1999, with slopes of −3.38 × 10−3 and − 8.00 × 10−4 year−1, respectively. However, they showed slight and significant (p

Mesoporous silica-coated multi-branched gold nanoparticles (bAu@mesoSiO2) aiming for enhanced Raman sensing for 4-bromomethcathinone (4-BMC) detection is reported. In this work, we present an effective strategy to probe the Raman signal of 4-MBC. Morphologies and optical properties of the synthesized materials with different [Au3+]/[Au0] ratios are characterized utilizing transmission electron microscopy (TEM), UV–vis and mid-infrared spectroscopy. Both experimental and theoretical (simulation) studies were investigated. Taking advantages of gold core branches that provide highly localized and strongly enhanced electromagnetic fields due to plasmon resonance, surface-enhanced Raman scattering (SERS) is observed. The experimental results show that the SERS intensity exhibits a 100-fold increase with the increased average length and quantity of gold branches (nano tips). The analytical performance yielded a detection limit of 0.1 mg/ml for the 4-MBC target within 5 mins. The sensing method will likely find further improvement and broad use in the forensic science. Besides rapid detection and portability, the combination of the Raman effect and enhanced materials imparts other notable advantages, such as its non-contact and free of reagents. Keywords: Multi-branched gold nanoparticles, SERS, Spectroscopy, 4-Bromomethcathinone, Rapid detection

In recent years, the haze incidents have occurred frequently in China. Therefore, more attention should be taken in comprehensively determination and analysis of the extended-ranges of volatile organic compounds (VOCs). Here, up to 99 non-methane VOCs (NMVOCs), including not frequently reported partial halocarbons and oxygenated VOC (OVOC) species, were monitored in atmosphere of Beijing. The mean concentration of total NMVOC (TNMVOC) decreased in the order of winter polluted days (216.05 μg m−3) > summer polluted days (127.01 μg m−3) > summer normal days (95.63 μg m−3) > winter normal days (50.25 μg m−3). The ethane to n-butane, ethylene to 1-butene, BTEX, acetaldehyde, acetone, n-hexanal, dichloromethane, chloroform and 1,2-dichloroethane, were determined to be the main composition in their respective alkane, alkene, aromatic, OVOC and halocarbon classes. The minor propylbenzene, diethylbenzene, ethyltoluene, and trimethylbenzene isomer ratios were within the narrow range of 1.3–3.21. Generally, the most abundant NMVOCs were alkanes in winter but OVOCs in summer. TNMVOC significantly positively correlated with PM10, PM2.5, CO, RH, SO2 (winter), NO2 (winter), but negatively with windspeed, SSD and PRS (winter). The opposite correlation was observed between TNMVOC and O3 in winter and summer. There was no meaningful correlation between TNMVOC and T, PRS (summer), SO2 (summer) and NO2 (summer). 3D surface graphs, built by MATLAB, were drawn to investigate the relationship between PM2.5 and NMVOC taking air quality parameters into account. The PM2.5 concentration increased non-linearly as TNMVOC concentration increased, with various surface graphs. Unlike other air quality parameters, O3 affected the relationship differently between winter and summer. The findings presented herein may provide a new train of thought for occurrence of haze.

Since the major/minor radius of the Sino-United Spherical Tokamak (SUNIST) is 0.3/0.23 m, respectively, the space left for magnetic diagnostics in the high field side (HFS) is quite limited. At the same time, a good signal-to-noise ratio and a high-frequency response (up to 1 MHz) are required for equilibrium reconstruction (ER) and Alfven eigenmode studies. Such a magnetic probe array must be extremely thin and tightly close to the central column, not exceeding the inner limiter and leaving the aspect ratio of the spherical tokamak unchanged. Therefore, the turn number and the shape of windings should be highly optimized to enable both a high-frequency response and an enough effective area. A 32-channel magnetic probe array fulfilling these requirements on the central column is designed, calibrated, and installed in the SUNIST. The array consists of 16 probes. Each of them consists of two perpendicular windings, which can measure toroidal and poloidal magnetic fields simultaneously. The effective area and frequency response of each probe are calibrated using a Helmholtz coil and an LCR bridge based on an equivalent probe-and-cable circuit model. After that, an expression of the magnetic diagnostic response to the field coil currents is used to calibrate the installation error. With the full coverage of magnetic probes in the poloidal direction, more reliable ER can be obtained, and the features of magnetohydrodynamic activities in the HFS can be studied.

Aberrant sterol lipid metabolism is associated with physiological dysfunctions in the aging brain and aging-dependent disorders such as neurodegenerative diseases. There is an unmet demand to comprehensively profile sterol lipids spatially and temporally in different brain regions during aging. Here, we develop an ion mobility-mass spectrometry based four-dimensional sterolomics technology leveraged by a machine learning-empowered high-coverage library (>2000 sterol lipids) for accurate identification. We apply this four-dimensional technology to profile the spatially resolved landscapes of sterol lipids in ten functional regions of the mouse brain, and quantitatively uncover ~200 sterol lipids uniquely distributed in specific regions with concentrations spanning up to 8 orders of magnitude. Further spatial analysis pinpoints age-associated differences in region-specific sterol lipid metabolism, revealing changes in the numbers of altered sterol lipids, concentration variations, and age-dependent coregulation networks. These findings will contribute to our understanding of abnormal sterol lipid metabolism and its role in brain diseases., Sterol lipids are crucial for maintaining proper brain function. Here, the authors combine ion mobility-mass spectrometry and machine learning to assemble a sterol lipid library and characterize differences in sterol lipids across ten brain regions and two age groups in mice.

Wastewater-based epidemiology (WBE) is expected to become a powerful tool to monitor the dissemination of SARS-CoV-2 at the community level, which has attracted the attention of scholars all over the world. However, there is not yet a standard protocol to guide its implementation. In this paper, we proposed a comprehensive technical and theoretical framework of relative quantification via qPCR for determining the virus abundance in wastewater and estimating the infection ratio in corresponding communities, which is expected to achieve horizontal and vertical comparability of the data using a human-specific biomarker as the internal reference. Critical factors affecting the virus detectability and the estimation of infection ratio include virus concentration methods, lag-period, per capita virus shedding amount, sewage generation rate, temperature-related decay kinetics of virus/biomarker in wastewater, and hydraulic retention time (HRT), etc. Theoretical simulation shows that the main factors affecting the detectability of virus in sewage are per capita virus shedding amount and sewage generation rate. While the decay of SARS-CoV-2 RNA in sewage is a relatively slow process, which may have limited impact on its detection. Under the ideal condition of high per capita virus shedding amount and low sewage generation rate, it is expected to detect a single infected person within 400,000 people., Graphical abstract Unlabelled Image

The global status of dioxin emissions across 150 countries/regions were compiled in this study. China, the major emitter of dioxin and the largest developing country, was chosen as an example to illustrate its emission reductions. The global dioxin emissions were about 97.0 kg TEQ/year, Asia and Africa emitted the most dioxins among the continents. Globally, open burning processes were the most important sources of dioxins. Dioxin emissions in developed countries have remained at low and stable level, while those in developing countries have remained at relatively high level or have continued to increase in recent years. It can be speculated that the global dioxin emissions will increase first and then decrease in the future. Chinese dioxin emissions were stable around 9 kg toxic equivalent (TEQ) in recent years, while 17 subcategories are the key sources of dioxin control in the future. Moreover, according to analysis toward China’s dioxin emission trend and sources, there is a large space for dioxins reduction in industries such as metal production, waste incineration and disposal. The results indicated that there is at least 30–70% of reduction scope in China based on three scenarios, and this will reduce the world's annual dioxin emissions by 2.7–6.8%.

Polycarbonate (PCL) has been widely used in tissue engineering, but its hydrophobicity and low biological activity limit its further promotion and application. By adding nanoparticles, the hydrophilicity and biological activity of PCL can be improved. In this study, different amounts of Ta (1–10%wt) were added to PCL, and then their mechanical and biological properties were studied in vitro. XRD found that 5%Ta-PCL has the highest crystallinity. At the same time, cell experiments CCK8, cell adhesion, osteogenic differentiation, and osteogenesis related gene expression showed that Ta can enhance the mechanical and biological properties of PCL, while 5% Ta-PCL showed the best mechanical and biological properties. This composite of tantalum and PCL could have a clinical potential for orthopedic implants.

The combined effects of climate change and human activities pose threat to the sustainable development of ecosystems. Human appropriation of net primary production (HANPP) has been extensively used as an important indicator for evaluating the sustainable development of the ecosystem. However, few studies quantitatively assessed the driving factors of HANPP. Based on Moderate-Resolution Imaging Spectroradiometer (MODIS) data, methods of net primary production (NPP) model and regression analysis, the spatial and temporal distribution of HANPP and its driving factors in the Qilian Mountains from 2005 to 2015 were illustrated. The results showed that the HANPP in the Qilian Mountains decreased gradually from both east to west and from south to north, showing a slight upward overall. The regions affected by human activities and climate change accounted for 26.8% and 73.2% respectively. Moreover, there was a significant negative impact between grain yield and HANPP, and a significant positive impact of either the annual sunshine duration, or livestock amount to HANPP.

The Yangtze River Delta (YRD) is one of the fastest developing areas in eastern China and contains many chemical industry parks. The profiles and sources of polycyclic aromatic hydrocarbons (PAHs) in soil in chemical industry parks and surrounding areas in the YRD were investigated by analyzing soil samples (n = 64) were collected in the YRD and Rudong chemical park (RD), a typical chemical park in the Yangtze River Delta. The total concentrations of 19 PAHs in the YRD soil samples were 16.3–4694 ng g−1 (mean 688 ng g−1), and the total concentrations of PAHs in RD were 21.6–246 ng g−1 (mean 75.4 ng g−1). The PAHs in soil in YRD were dominated by four-ring and five-ring PAHs, and the PAHs in RD were dominated by two-ring and three-ring PAHs. It suggested that PAHs may have been supplied to soil in YRD predominantly through coal combustion and vehicle emissions, PAHs in the soil of RD may be due to the volatilization and leakage of chemical raw material. According to the different distribution characteristics of PAHs, the ratio (1.5) of (2 + 3) rings/4 rings was proposed to identify the chemical source of PAHs. The PAH isomer ratios and principal component analysis/multiple linear regression (PCA/MLRA) results indicated that PAHs concentrations in soil in the YRD and RD are mainly supplied by industrial and traffic emissions. Incremental lifetime cancer risks (ILCRs) indicated that PAHs in soil pose negligible cancer risks to children and adults, but much stronger risks to children than adults.

In order to solve the opioid crisis which broke out in the United States, the diffusion model suitable for the problem is established, inspired by the error inverse propagation model. By observing the diffusion characteristics of opioids between the five states and their counties, the locations where each state began to use specific opioids are identified and the diffusion characteristics of the corresponding programmes are summarized. Ultimately, the opportunity for the government to focus on such cases and the threshold of the corresponding drug is found, and the location and time of the case are predicted.

Clay minerals are an important host for arsenic in many arsenic-affected areas. The role of bioreduction of structural Fe(III) in clay minerals in the mobilization of arsenic from clay minerals, however, still remains unclear. In this study, Fe(III) reducing bacterium, As(V) reducing bacterium, and Fe(III)-As(V) reducing bacterium were employed to investigate the possible bioreduction pathways for arsenic release from Nontronite NAu-2. Results demonstrated that microbial reduction controlled arsenic mobilization from NAu-2 through Fe(III), As(V), and simultaneous Fe(III)-As(V) reduction pathways. Although the bioreduction of structural Fe(III) led to a negligible dissolution of NAu-2, it triggered a significant release of arsenic from NAu-2. The bioreduction of tetrahedral Fe(III) initiated the release of As(V), and the further bioreduction of octahedral Fe(III) induced the release of As(III) in NAu-2. In addition, bioreduction of As(V) resulted in the desorption and transformation of As(V) from NAu-2. Simultaneous bioreduction of Fe(III) and As(V) led to an almost complete release of As(V) from NAu-2. These findings suggest that simultaneous Fe(III)-As(V) reduction was the dominant pathway governing As(V) release from NAu-2, while structural Fe(III) reduction controlled As(III) release from NAu-2. Therefore, the bioreduction of iron-bearing clay minerals has a great potential for arsenic mobilization in the subsurface environment.

Tyrosinase is the key enzyme for the metabolism of tyrosine and inherently comprises both monophenolase activity and diphenolase activity. A real-time fluorometric assay method was established to exclusively monitor the monophenolase activity by eliminating interference from diphenolase reactions through a combination of borate and hydroxylamine. Synthetic matrices comprised of tyrosine and DOPA (L-3,4-dihydroxyphenylalanine) preincubated with tyrosinase with the consistent sum concentration of 70 μM to mimic the monophenolase reaction mixture in borate buffer according to law of mass conservation. A matrix-matched calibration curve for determination of tyrosine was established using the synthetic matrices as standard sample to eliminate spectral interference from DOPA. The limit of detection (LOD) for tyrosine was 0.61 μM. The time course for consumption of tyrosine was established to measure the initial velocity through real-time reading out the tyrosine fluorescence intensity of the reaction mixture in a cuvette in situ. The assay worked in the monophenolase activity range from 0.2839 to 1.7308 U mL−1 with LOD of 0.0851 U mL−1. The proposal sensing system successfully afforded a prospective potential for application in enzyme kinetics and screening of inhibitor.

Chironomidae is the most ecologically diverse insects in aquatic and semi-aquatic habitats. Propsilocerus akamusi (Tokunaga) is a dominant and ubiquitous chironomid species in Eastern Asia and its morphologically unique larvae are also considered as indicator organisms to detect water contamination, potential toxicity and waterborne pathogens. Since few studies to date have focused on the olfactory system of P. akamusi, our study aims to elucidate the potential functions of chemosensory genes in P. akamusi. In our study, we found that although signals released from male groups might attract female swarmers, it was a completely male-dominated mating process. Sequencing the transcriptome of P. akamusi on an Illumina HiSeq platform generated 4.42, 4.46 and 4.53 Gb of clean reads for heads, legs, and antennae, respectively. 27,609 unigenes, 20,379 coding sequences (CDSs), and 8,073 simple sequence repeats were finally obtained. The gene-level differential expression analysis demonstrated variants among three different tissues, including 2,019 genes specifically expressed in heads, 1,540 genes in legs, and 2,071 genes in antennae. Additionally, we identified an assortment of putative olfactory genes consisting of 34 odorant binding proteins, 17 odorant receptors, 32 gustatory receptors, 22 ionotropic receptors, six chemosensory proteins as well as 3 sensory neuron membrane proteins; their relative abundances in the above three tissues were also determined by RT-qPCR. Our finding could allow a more plausible understanding of certain olfaction-mediated behaviors in groups of this macroinvertebrate.

International audience; In this paper, we discuss several different styles of multi-period mean-variance portfolio optimization problems under the serially correlated returns. We derive the time-consistent strategies for the classical multi-period mean-variance optimization with and without risk-free asset using a backward induction approach. We also propose an alternative multi-period mean-variance model, and the corresponding time-consistent strategies are derived. Whereafter, we provide some portfolio evaluation indexes and perform extensive empirical studies based on real data, aiming to provide useful advice for investors. To a large extent, the empirical results answer one important and practical question: in actual investment situations, which strategy is preferred by different investors?

Anthropogenic warming has been projected to increase global drought for the 21st century when calculated using traditional offline drought indices. However, this contradicts observations of the overall global greening and little systematic change in runoff over the past few decades and climate projections of future greening with slight increases in global runoff for the coming century. This calls into question the drought projections based on traditional offline drought indices. Here we calculate a widely used traditional drought index (i.e., the Palmer Drought Severity Index, PDSI) using direct outputs from 16 Coupled Model Intercomparison Project Phase 5 (CMIP5) models (PDSI_CMIP5) such that the hydrologic consistency between PDSI_CMIP5 and CMIP5 models is maintained. We find that the PDSI_CMIP5-depicted drought increases (in terms of drought severity, frequency, and extent) are much smaller than that reported when PDSI is calculated using the traditional offline approach that has been widely used in previous drought assessments under climate change. Further analyses indicate that the overestimation of PDSI drought increases reported previously using the PDSI is primarily due to ignoring the vegetation response to elevated atmospheric CO2 concentration ([CO2]) in the traditional offline calculations. Finally, we show that the overestimation of drought using the traditional PDSI approach can be minimized by accounting for the effect of CO2 on evapotranspiration.

The lack of kinetic parameters of VOC photochemical conversion especially in the presence of NO and O3, and product information, will result in the incomplete understanding for the occurrence of haze. In the present study, the photochemical conversion of toluene, one of most significant hydrocarbons of VOCs, in toluene, toluene/NO, toluene/O3 and reaction systems was assessed for up to 4 days in a smog chamber at 278 K and 308 K. The results indicated that the addition of NO and O3 promoted the conversion of toluene. The first-order kinetic rate constants of toluene assessed in the toluene reaction system at 278 K and 308 K were 0.12 and 0.19 day−1, respectively. The second-order kinetic rate constants of toluene assessed in the toluene/NO were 0.1 × 10−13 cm3 molecule−1 day−1 (at 278 K) and 0.9 × 10−13 cm3 molecule−1 day−1 (at 308 K), and those in the toluene/O3 reaction systems were 0.06 × 10−12 cm3 molecule−1 day−1 (at 278 K) and 0.11 × 10−12 cm3 molecule−1 day−1 (at 308 K). The small difference of second-order kinetic rate constants between 278 K and 308 K obtained for the toluene/O3 system when compared with the toluene/NO system indicated the reduced reaction sensitivity of O3 to the temperature. Several dozens of large molecule products containing up to O6 heteroatoms were identified by positive ion atmospheric pressure photoionization (+APPI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), with double bond equivalents up to 18, and carbon numbers ranging within 12–38, respectively. The findings presented herein may provide a new train of thought for the photochemical reaction process of toluene and its conversion in ambient air.

This paper aims to investigate a class of second-order suplinear Hamiltonian systems generated by impulsive effects. By introducing a new energy functional and employing the fountain theorem, the existence of infinitely many rotating periodic solutions is obtained.

Size-dependent yield strength is a common feature observed in miniaturized crystalline metallic samples, and plenty of studies have been conducted in experiments and numerical simulations to explore the underlying mechanism. However, the transition in yield strength from bulklike to size-affected behavior has received less attention. Here a unified theoretical model is proposed to probe the yield strength of crystalline metallic materials with sample size from nanoscale to macroscale. We show that the transition in yield strength versus size can be fully explained by the competition between the stresses required for dislocation source activation and dislocation motion, which is regulated by dislocation density, irradiation defect, grain boundary, and so on. Based on various grain boundary densities, the extended Hall-Petch relation, incorporated into the unified model, captures the reverse size effect for polycrystalline samples. The proposed model predictions agree well with reported experimental measurements of various specimens, including the prestrained nickel, irradiated copper, ultrafine grain tungsten, and so on.

An inelastic excitation and cluster-decay experiment ^{2}H(^{16}C,^{4}He+^{12}Be or ^{6}He+^{10}Be)^{2}H was carried out to investigate the linear-chain clustering structure in neutron-rich ^{16}C. For the first time, decay paths from the ^{16}C resonances to various states of the final nuclei were determined, thanks to the well-resolved Q-value spectra obtained from the threefold coincident measurement. The close-threshold resonance at 16.5 MeV is assigned as the J^{π}=0^{+} band head of the predicted positive-parity linear-chain molecular band with (3/2_{π}^{-})^{2}(1/2_{σ}^{-})^{2} configuration, according to the associated angular correlation and decay analysis. Other members of this band were found at 17.3, 19.4, and 21.6 MeV based on their selective decay properties, being consistent with the theoretical predictions. Another intriguing high-lying state was observed at 27.2 MeV which decays almost exclusively to ^{6}He+^{10}Be(∼6 MeV) final channel, corresponding well to another predicted linear-chain structure with the pure σ-bond configuration.

Northwest China is characterized by a high water deficit and regular water resource shortages. These issues have become limiting factors for agricultural and socioeconomic development. Based on a trend-preserving method of bias correction, we calibrated the maximum temperature and minimum temperature in four CMIP5 GCMs (CNRM, IPSL, BCC, and CMCC). Then, we investigated variations in the regional crop water requirement (CWR) in the total growth stages for five main crops (cotton, spring corn, summer corn, spring wheat, and winter wheat) in the past (1961–2005) and future (2006–2100). The results suggest that the MK test yielded insignificant decreasing CWR trends in the total growth stages of cotton (0.10 mm/year), spring corn (0.13 mm/year), and spring wheat (0.05 mm/year) and insignificant increasing trends for summer corn (0.02 mm/year) and winter wheat (0.32 mm/year) historically. In the future period, for the same type of crops (cotton), the CWRs in all scenarios (RCP 2.6, 4.5, and 8.5 scenarios) for all GCMs exhibited significant positive trends; for the same GCM (BCC), the CWRs projected for five major crops in the RCP 4.5 and 8.5 scenarios all exhibited extremely significant MK trends (99%); in addition, the CWRs’ rate increases of the five crops projected in RCP8.5 scenario by BCC exhibited the following order: winter wheat (1.25 mm/year), summer corn (1.15 mm/year), spring corn (1.02 mm/year), cotton (0.97 mm/year), and spring wheat (0.87 mm/year). The maximum CWRs of winter wheat were mainly observed in southeastern Northwest China, while those of the other four crops occurred in southern Xinjiang.

Rapid elevation-dependent warming (EDW) in high mountain environments can accelerate the rate of change in permafrost and further induce the degradation of alpine tundra systems. However, how changes in area of alpine tundra response to EDW is difficult to be directly quantified at regional scales. Here, we project future changes in areal extent of the Koppen “alpine tundra” climate type in the Tibetan Plateau (TP), which is a potential indicator describing the climate conditions for the development of alpine tundra system, based on a suite of latest Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models under two emission scenarios (representative concentration pathways: RCP 4.5 and RCP 8.5). The results indicated that the Koppen “alpine tundra” climate type would gradually decrease in the TP for three future periods: 2011–2040, 2041–2070, and 2071–2100, especially under the RCP8.5 scenario. The decline in area of Koppen “alpine tundra” climate type mainly occurs above 2500 m above sea level (ASL) due to the EDW (> 10 °C) in the warmest months. The projected changes in area of “alpine tundra” climate type are overall consistent among different climate models, emission scenarios, and post-processing approaches (bias correction or not) used. The results obtained would thus deepen our understanding of future elevation-dependent warming and its potential influences on alpine tundra ecosystems in the Tibetan Plateau.

Precipitation extremes are expected to increase by 7% per degree of warming according to the Clausius–Clapeyron (CC) relation. However, this scaling behavior is inappropriate for high temperatures and short-duration precipitation extremes. Here, daily data from 702 stations during 1951–2014 and hourly data from 8 stations during 2000–15 are used to examine and explain this behavior in China. Both daily and hourly precipitation extremes exhibit an increase in temperature dependency at lower temperatures. The CC scaling transitions from positive to negative rates with temperatures greater than 25°C. Unlike the increase in daily data, which is similar to single-CC (1CC) scaling, the increase in hourly data resembles super-CC (2CC) scaling for temperatures greater than 13°C. Results show that the precipitation extremes are controlled by water vapor for a given temperature. At lower temperatures, precipitation extremes exhibit a positive linear dependence on daily actual vapor pressure whose value is almost equal to the saturated vapor pressure at a given temperature. At higher temperatures, actual vapor pressure has difficulty maintaining a consistent increasing rate because of the exponential increasing of the saturated vapor pressure. Higher temperatures result in larger vapor pressure deficits, which lead to sharp decreases in precipitation extremes. Similar scaling behaviors are obtained in 10 river basins over China, where the breaking point temperature increases from 17°C along the northwest inland area to 25°C along the southeast coast. These behaviors demonstrate that precipitation extremes are firmly linked to temperature when there is sufficient moisture at lower temperatures and limited by insufficient moisture at higher temperatures. Overall, precipitation extreme events require more attention in a warming climate.