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High aspect ratio two-dimensional Ti3C2Tx MXene flakes with extraordinary mechanical, electrical, and thermal properties are ideal candidates for assembling elastic and conductive aerogels. However, the scalable fabrication of large MXene-based aerogels remains a challenge because the traditional preparation method relies on supercritical drying techniques such as freeze drying, resulting in poor scalability and high cost. Herein, the use of porous melamine foam as a robust template for MXene/reduced graphene oxide aerogel circumvents the volume shrinkage during its natural drying process. Through this approach, we were able to produce large size (up to 600 cm3) MXene-based aerogel with controllable shape. In addition, the aerogels possess an interconnected cellular structure and display resilience up to 70% of compressive strain. Some key features also include high solvent absorption capacity (∼50-90 g g-1), good photothermal conversion ability (an average evaporation rate of 1.48 kg m-2 h-1 for steam generation), and an excellent electrothermal conversion rate (1.8 kg m-2 h-1 at 1 V). More importantly, this passive drying process provides a scalable, convenient, and cost-effective approach to produce high-performance MXene-based aerogels, demonstrating the feasibility of commercial production of MXene-based aerogels toward practical applications.

Schiff bases that are generally formed from condensation reactions of aldehydes (or ketones) and amino groups could also be produced by a photodriven one-pot tandem reaction between alcohols and nitro compounds, in our case. Herein, TiO2-x porous cages derived from NH2-MIL-125 by a self-sacrificing template route are used to study the organic transformation and exhibit 100% conversion efficiency of nitrobenzene and 100% selectivity for Schiff bases in the system of benzyl alcohol (5 mL) and nitrobenzene (41 μL) upon light irradiation, but hydrogen by dehydrogenation of benzyl alcohol cannot be detected. Successful occurrence of the organic transformation is mainly attributed to Ti(III)-oxygen vacancy associates. Surface oxygen vacancy-related Ti(III) sites are responsible for binding with nitro groups, and low-coordinated Ti5c sites selectively adsorb hydroxyl groups of benzyl alcohol. The Ti(III) and oxygen vacancy associates capture photogenerated electrons for achievement of multielectron reduction of nitrobenzene and the subsequent Schiff base condensation reaction with the as-formed benzaldehyde.

The phenomenon that different molecular packing modes in aggregates result in different optical properties has attracted intense attention, since it can provide useful information to establish the relationship between the micro- and macro-world. In this paper, DBTDO-DMAC was designed with 9,10-dihydro-9,9-dimethylacridine (DMAC) as electron donor. DBTDO-DPA and DBTDO-Cz were designed for comparison, which adopted diphenylamine (DPA) with twisted structure and carbazole (Cz) with planar structure as donors, respectively. As expected, two polymorphs (Crystal G and Crystal Y) of DBTDO-DMAC were obtained and exhibited distinct properties. Crystal G originating from planar conformation exhibited mechanochromism (MC) phenomenon and the emission color changed from green to yellow with a redshift of 35 nm after grinding. Nevertheless, Crystal Y with folded conformation displayed obvious room-temperature phosphorescence (RTP) with yellow afterglow. Careful single crystal analyses, powder X-ray diffraction and theoretical calculation reveal that the different emissive behaviors are highly related to the molecular conformation and packing modes. The successful adjustment of molecular conformation provides some guidance in the design of other MC and/or RTP luminogens, broadens the molecule family with the tunable molecular conformation and opens up a new avenue for exploring possible adjustment of molecular packing in aggregates.

Capacity fading of Li-rich cathodes in the cycling process is mainly caused by the irreversible side reactions at the interface of electrode and electrolyte by reason of the lack of a corrosion resistant surface. In this work, isocyanate-related functional groups (-N═C═O groups and polyamide-like groups) were tightly bonded on the surface of Li-rich oxides through a urea decomposition gas heat-treatment. The surface isocyanate functionalization inhibits the side reaction of PF5 hydrolysis to give LixPFyOz and HF species at the surface of Li-rich materials in the cycle process. As compared to the untreated Li-rich sample U0, the samples with the spinel-like layer and isocyanate functionalized surface exhibited an enhanced cycle stability. The capacity retention of the treated sample U3 reached as high as 92.6% after 100 cycles at the current density of 100 mA/g, larger than 66.8% for the untreated sample. Even at a higher current density of 1000 mA/g, sample U3 gives a capacity retention of 81.7% after 300 cycles. The findings of this work reveal the importance of surface isocyanate functionalization in restraining the surface side reactions and also suggest an effective method to design Li-rich cathode materials with better electrochemistry performance.

Ceramic capacitors require promising energy storage properties to meet the demands of electronic industry which can be tailored by ferroelectric polarization and electrical breakdown strength. Electrical breakdown exhibits close relation to leakage current in advanced dielectric materials when stimulated by high levels of electric field. The suppression of leakage can be an effective strategy to elevate dielectric breakdown. In this work, Zr ions were employed to replace Ti ions in Ba0.3Sr0.7TiO3 ceramics to achieve the improvement of dielectric breakdown and then increase energy storage ability. Zr doping can obviously reduce the leakage current more than an order of magnitude by blocking the path between two adjacent Ti ions and increasing the distance of electron hopping. A promising energy storage density can be obtained with good fatigue endurance upto cycles of 105. This indicates that the strategy of suppressing leakage by trace amount of Zr doping is an effective approach to tailor energy storage behavior of dielectric ceramics.

Acute lower respiratory infections caused by respiratory viruses are common and persistent infectious diseases worldwide and in China, which have pronounced seasonal patterns. Meteorological factors have important roles in the seasonality of some major viruses. Our aim was to identify the dominant meteorological factors and to model their effects on common respiratory viruses in different regions of China. We analysed monthly virus data on patients from 81 sentinel hospitals in 22 provinces in mainland China from 2009 to 2013. The geographical detector method was used to quantify the explanatory power of each meteorological factor, individually and interacting in pairs. 28369 hospitalised patients with ALRI were tested, 10387 were positive for at least one virus, including RSV, influenza virus, PIV, ADV, hBoV, hCoV and hMPV. RSV and influenza virus had annual peaks in the north and biannual peaks in the south. PIV and hBoV had higher positive rates in the spring summer months. hMPV had an annual peak in winter spring, especially in the north. ADV and hCoV exhibited no clear annual seasonality. Temperature, atmospheric pressure, vapour pressure, and rainfall had most explanatory power on most respiratory viruses in each region. Relative humidity was only dominant in the north, but had no significant explanatory power for most viruses in the south. Hours of sunlight had significant explanatory power for RSV and influenza virus in the north, and for most viruses in the south. Wind speed was the only factor with significant explanatory power for human coronavirus in the south. For all viruses, interactions between any two of the paired factors resulted in enhanced explanatory power, either bivariately or non-linearly., 6 figures and tables

In lime concretion black soil, a two-factor (tillage and irrigation) split block experiment from 2015 to 2017 was conducted to identify whether their combination is suitable for the improvement of winter wheat yield and water use efficiency. The main treatments were subsoiling (SS) and rotary tillage (RT), with secondary treatments of three irrigation regimes: no irrigation during the whole growth period (W0), irrigation at jointing stage (W1), and irrigation at both jointing and anthesis stages (W2). In combination with a soil column experiment, the contribution of the root system in different soil layers to yield was clarified. The results indicated that both tillage and irrigation significantly influenced the spatiotemporal distributions of the root systems and yield components, while tillage produced the strongest effect. Compared with RT, SS significantly promoted the root penetration and delayed root senescence in deep soil layers. With increasing soil depth, each root configuration parameter (dry root weight density, DRWD; root length density, RLD; root surface area per unit area, RSA; root volume per unit area, RV) gradually decreased, and the peak appearance times of each root parameter in RT and three parameters (RLD, RSA and RV) in SS were postponed from heading to anthesis and from anthesis to filling stage, respectively. The average post-peak attenuation values at soil layers from 60 to 100 cm in W1 were less than those in W0 and W2. SSW1 generated the highest grain yields, with an average increase of 31.88% compared with the yield in RTW0. Root systems at three soil layers (0–40 cm, 40–80 cm and below 80 cm) differentially contributed to grain yields with 78.32%, 12.09% and 9.59%, respectively. The growth peak of the deep root system in SSW1 was postponed to the filling stage, and the post-peak attenuation declining rates were also slowed. Therefore, SSW1 is an effective cultivation method improving grain yields and water use efficiency in lime concretion black soil.

Biomass-based composites are of immerse importance because they allow combining properties in ways that are not found in nature. This work reports facile routs to produce pressure sensor in large scale from biomass kapok fibers and natural rubber. Two different strategies were applied to introduce conductive elements into the pressure sensor and are systemically compared, which include carbonization of the tubular kapok fibers and coating the fibre with conductive polymer. When used as a pressure sensor, the kapok fiber and natural rubber-based composites can respond logarithmically to the loading in the compressive strain range of 0 ~ 15% with excellent recyclability. As a prototype of the concept for practical application, a weight scale was constructed using the kapok fiber and natural rubber-based composites and showed distinct weight-dependent resistance changes, being feasible for measuring weight within a certain weight range. Besides, the strategy based on conductive polymer enables the pressure sensor to be insulative at its original state and become conductive when pressed, hereby making the composite a potential pressure-sensing material and pressure-responsive circuit switch. This study provides a platform for developing biomass-based electronic pressure sensors.

In this article, a time two-mesh (TT-M) algorithm combined with the H1-Galerkin mixed finite element (FE) method is introduced to numerically solve the nonlinear distributed-order sub-diffusion model, which is faster than the H1-Galerkin mixed FE method. The Crank-Nicolson scheme with TT-M algorithm is used to discretize the temporal direction at time $t_{n+\frac {1}{2}}$ , the FBN-𝜃 formula is developed to approximate the distributed-order derivative, and the H1-Galerkin mixed FE method is used to approximate the spatial direction. TT-M mixed element algorithm mainly covers three steps: first, the mixed finite element solution of the nonlinear coupled system on the time coarse mesh ΔtC is calculated; next, based on the numerical solution obtained in the first step, the numerical solution of the nonlinear coupled system on time fine mesh ΔtF is obtained by using Lagrange’s interpolation formula; finally, the numerical solution of the linearized system on time fine mesh ΔtF is solved by using the results in the second step. The existence and uniqueness of the solution for our numerical scheme are shown. Moreover, the stability and a priori error estimate are analyzed in detail. Furthermore, numerical examples with smooth and nonsmooth solutions are given to validate our method.

The ability of storing electrostatic energy for a capacitor is largely dependent on the energy storage performances of the material used in the electronic components. In this case, a composition-driven Bi0.5Na0.5TiO3-based system, (1−x)(0.84Bi0.5Na0.5TiO3−0.16Bi0.5K0.5TiO3)−xBi(Mg0.5Ti0.5)O3 (NTB-KBT-100xBMT, x = 0.04–0.14) was designed and the enhanced energy storage density and efficiency with good thermal insensitivity were confirmed. The introduction of BMT can induce the relaxor characteristic due to the deconstruction of the ferroelectric long-range order, leading to the increase in dielectric breakdown and the improved energy storage performances. Particularly, the NTB-KBT-8BMT ceramic exhibits a high stored energy density (Wtotal = 2.88 J/cm3) and recoverable energy density (Wrec = 2.42 J/cm3) with good energy efficiency (η = 84.0%) under 320 kV/cm, indicative of potential application for energy storage components. Moreover, the NTB-KBT-8BMT ceramic exhibits typical temperature-independent character in a wide temperature range from 30 to 140 °C due to broad diffused phase transition. It can be concluded that constructing relaxor ferroelectrics is an effective approach to design novel dielectrics for pulse power applications.

A reaction-diffusion predator-prey system with prey-taxis and predator-taxis describes the spatial interaction and random movement of predator and prey species, as well as the spatial movement of predators pursuing prey and prey evading predators. The spatial pattern formation induced by the prey-taxis and predator-taxis is characterized by the Turing type linear instability of homogeneous state and bifurcation theory. It is shown that both attractive prey-taxis and repulsive predator-taxis compress the spatial patterns, while repulsive prey-taxis and attractive predator-taxis help to generate spatial patterns. Our results are applied to the Holling-Tanner predator-prey model to demonstrate the pattern formation mechanism.

Developing monoclonal antibodies (mAbs) for cancer immunotherapy is expensive and complicated. Nanobodies are small antibodies possessing favorable pharmacological properties compared with mAbs, but have limited anticancer efficacy due to the lack of an Fc region and poor pharmacokinetics. In this context, engineered universal endogenous antibody-recruiting nanobodies (UEAR Nbs), as a general and cost-effective approach, were developed to generate functional antibody-like nanobodies that could recapitulate the Fc biological functions for cancer immunotherapy. The UEAR Nbs, composed of the IgG binding domain and nanobody, were recombinantly expressed in E. coli and could recruit endogenous IgGs onto the cancer cell surface and trigger potent immune responses to kill cancer cells in vitro. Moreover, it was proved that UEAR Nbs displayed significantly improved half-lives in vivo. The in vivo antitumor efficacy of UEAR Nbs was demonstrated in a murine model using EGFR positive triple-negative breast cancer (TNBC)., Universal endogenous antibody recruiting nanobodies (UEAR Nbs), composed of IgGs binding domain and nanobody, could redirect endogenous IgGs onto target cell surfaces and evoke potent immune responses to eliminate cancer cells in vitro and in vivo.

Exploring high-performance ceramics has been a great challenge for advanced electronic devices due to their limited capacitive energy storage densities in high-voltage pulse applications. The refinement of the microstructures can considerably optimize energy storage performances of dielectric ceramics by tailoring dielectric breakdown. Here, two-step sintering was employed to refine the microstructures of the lead-free 2.0 mol% Mn-doped 0.55 (0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-0.45SrTiO3 bulk ceramics to offer the possibility of increasing energy storage performances. Compared with conventional sintering, fine grains by two-step sintering can be obtained, resulting in the obviously enhanced dielectric breakdown due to the increased fraction of grain boundary and the suppressed movement of domain walls. An ultrahigh charge energy storage density of 2.98 J/cm3 with a moderate efficiency (η) of 73.1% can be achieved at 28 kV/mm, accompanying with excellent temperature insensitivity in a wide range from 30 to 180 °C compared with the previous Na0.5Bi0.5TiO3-based derivatives. This work presented here strongly indicates that two-step sintering is a promising way to optimize the microstructural morphology and electrical performances of dielectric ceramics.

Wearable conducting polymer-based NH3 sensors are highly desirable in real-time environmental monitoring and human health protection but still a challenge for their relatively long response/recovery time and moderate sensitivity at room temperature. Herein, we present an effective route to fulfill this challenge by constructing porous and neural network-like Au/polypyrrole (Au/PPy) electrospun nanofibrous film with hollow capsular units for NH3 sensor. Taking the unique architecture and synergistic effect between Au and PPy, our sensor exhibits not only super-rapid response/recovery time (both ∼7 s), faster than all reported sensors, but also stable and ultrahigh sensitivity (response reaches ∼2.3 for 1 ppm NH3) at room temperature even during repeated deformation. Furthermore, good selectivity has been also achieved. These outstanding properties make our sensor hold great potential in real-time NH3-related disease diagnosis and environmental monitoring at room temperature.

In this article, a fast time two-mesh (TT-M) finite element (FE) method for the two-dimensional space fractional Gray–Scott model is studied and discussed to get the numerical solutions effectively. The method mainly includes three steps: firstly, one uses an iterative method for solving the coupled nonlinear system on the time coarse grid; secondly, by an interpolation formula, one can get any coarse values on the time fine mesh; finally, based on the computed coarser solutions, a linear FE system on time fine mesh can be constructed by using the two-variables Taylor’s formula. Here, some theoretical results, which include stability and a priori error for the fully discrete scheme, are analyzed and proved. Furthermore, the computing data are given to verify the correctness of the theoretical results and to illustrate that the TT-M FE algorithm can reduce the computing time.

Gas adsorption properties of key natural fibres were investigated through monitoring the adsorption process of ammonia onto wool and cotton by time-resolved infrared spectroscopy. It was found that...

Increasing contamination of urban soil by persistent organic pollutants is a major environmental issue. The purpose of the present study was to investigate the distribution, source and human health risk of polycyclic aromatic hydrocarbons (PAHs) in different functional areas in Zhengzhou City, China. Total 130 soil samples were collected from surface layer (0–10 cm) in urban road, overpass, residential area and park in the city during January 2019. Concentrations of ∑PAH16 in the urban soil ranged from 49.90 to 11,565 µg kg−1 and seven carcinogenic PAHs accounted for 69% of the total PAHs. The mean concentrations of PAHs decreased in the following order: urban road > overpass > residential area > park. Analysis based on diagnostic rate demonstrated that PAHs mainly originated from pyrolysis sources including traffic emissions and combustion of coal and biomass. Health risk assessment indicated that PAHs in urban road in the city have potential carcinogenic risks to residents. The present study suggested that the control of urban PAHs pollution in Zhengzhou City should be strengthened.

Bright emission of organic luminogens at aggregated state has attracted increasing attention for their potential applications in opto-electronic devices and bio-/chemo-sensors. In this article, upon the introduction of different substituents (Br, Ph and TPh) to the large conjugated core of 9-methyl-9 H -dibenzo[ a , c ]carbazole (DBC) moiety, the resultant luminogens demonstrated PL quantum yields in solid state ranging from 4.81% to 47.39%. Through the systematic investigation of molecular packing, together with theory calculation, the strong intermolecular electronic coupling in the dimers is proved as the main factor to the bright emission in the solid state. The results afforded a new avenue to investigate the intrinsic relationship among the molecular structures, packing modes and emission properties.

Bio-inspired polarization navigation is a promising navigation method inspired by insects’ autonomous foraging and homing behaviour. Many insects acquire their spatial orientation by sensing the polarization pattern of the skylight. We propose utilization of solar meridian in the polarized skylight as an orientation cue because of its significant features. Using its features, we then design and construct an imaging polarization navigation prototype. The prototype consists of a field-division polarization imaging sensor, the corresponding software, an interface, and the solar-meridian recognizing and measurement algorithm. The field-division polarization imaging sensor is the core component of the prototype and acquires polarized intensity images. To adapt to the demand of real-time on navigation system, we then propose an optimized real-time polarization image processing and pattern recognition algorithm based on Hough transform. The azimuth measurement accuracy of the sensor is then calibrated using a facility that is able to get higher azimuth accuracy by measurement of the star light. To verify the navigation capability of the developed system, we use a dynamic experiment, where the prototype is installed on the top of a vehicle and its navigation performance is compared with GNSS.

The ferroelectric material of BaTiO3 was introduced in the electron transport layer (ETL) of perovskite solar cells to improve the photogenerated electron transport. The sintered BaTiO3 thin films were polarized at different applied electric fields, and then TiO2 thin films were further deposited to be used as the ETL. The electric field was positively applied across the BaTiO3 thin film, and the photocurrent density of solar cell can be increased obviously. The results of electrochemical impedance and photoluminescence spectra indicate that the ordered polarization dipole moment inside the BaTiO3 thin film can accelerate the transport of photogenerated electrons from the ETL to the conducting glass substrate. The short-circuit photocurrent of perovskite solar cell is increased and thus the light-to-electric conversion efficiency is effectively improved to 13%. It is increased by 14% compared with that without the application of the positive electric field across the BaTiO3 thin film.

Palladium nanoparticle (PdNP) loaded cotton fabrics were successfully prepared through in situ synthesis of PdNPs via heating. The resulting PdNP-treated cotton fabrics showed color originated from the localized surface plasmon resonance (LSPR) effect of PdNPs, with satisfactory color fastness to washing and rubbing, and enhanced UV protection properties. The PdNP-treated cotton greatly accelerated the reduction reaction of 4-nitrophenol (4-NP) by sodium borohydride, exhibiting distinct catalytic activity. More importantly, the PdNP-treated cotton fabric displayed enzyme mimicking activity to catalyze the oxidation of a chromogenic enzymatic substrate (3,3′,5,5′-tetramethylbenzidine) in the presence of hydrogen peroxide, which provides a visual sensing platform for hydrogen peroxide. This work demonstrated a versatile approach to fabricate PdNP-treated cotton fabrics with multiple functions. This study on the surface modification of cotton fabrics with PdNPs could promote the practical applications of functional fibrous materials in catalysis and sensing fields.

Spatial heterogeneity represents a general characteristic of the inequitable distributions of spatial issues. The spatial stratified heterogeneity analysis investigates the heterogeneity among vari...

An indoor simulation experiment was conducted to explore the effects of cuticular wax content and specific leaf area (SLA) on accumulation and distribution of PAHs in different tissues of wheat leaf. Three levels (0, 1.25, 6.0 mg L−1) of mixed solution of five PAHs (Σ5PAHs) including phenanthrene (PHE), anthracene (ANT), pyrene (PYR), benz[a]anthracene (BaA), and benzo[a]pyrene (BaP) were sprayed on leaves of seven varieties of winter wheat for every other day during 20 consecutive days. Shoot and root biomass of wheat under 6.0 mg L−1 Σ5PAHs exposure were 5.87 and 0.33 g, which were significantly (p

Finish-machined high-volume-fraction SiCp/Al (SiC-particle-reinforced Al matrix) composites tend to have poor surface roughness. To explore the effects of various parameters on the surface roughness of these materials, an orthogonal experiment array L16 (4)4 was designed based on the tool nose radius, cutting depth, feed rate, and cutting speed. Surface roughness values were obtained using a TR200 portable roughness metre during finishing cutting experiments, which were conducted on a Mazak CNC lathe. The Taguchi approach and analysis of variance were used to analyse the significance of the various parameters. A model was developed based on a polynomial regression equation to predict the optimum surface roughness and its corresponding parameters. The confirmation experiments showed that there was good consistency in the optimum surface roughness between the predicted and experimental results.

Rhamnose and sTn antigen were co-conjugated to bovine serum albumin (BSA), a weakly immunogenic carrier protein, for cancer vaccine development. The immune responses against sTn have been significantly augmented with the involvement of Rha-specific antibodies to enhance antigen uptake.

In this work, the thermoelectric performance of p-type PbSe was improved dramatically by enhancing the Seebeck coefficient and reducing electronic thermal conductivity through CdTe alloying. CdTe alloying effectively increased the effective mass of p-type Pb0.98Na0.02Se due to band flattening and promoting the valence band convergence, which contributed to a high Seebeck coefficient of ∼238 μV K−1 at 860 K and large power factor of ∼18.2 μW cm−1 K−2 at 860 K for Pb0.98Na0.02Se + 4% CdTe. Furthermore, CdTe alloying reduced the carrier mobility of Pb0.98Na0.02Se due to the enhanced scattering of impurity atoms, which results in a remarkable reduction of electronic thermal conductivity. As a result, due to its higher power factor and lower thermal conductivity, a high thermoelectric figure of merit ZT ∼1.5 at 860 K was achieved for Pb0.98Na0.02Se + 4% CdTe. This paper provides one novel approach to enhance the thermoelectric performance of p-type PbSe through synergistically manipulating electrical and thermal transport properties.

Mechanoluminescence (ML) and room-temperature photophosphorescence (RTP) were achieved in polymorphisms of a triphenylamine derivative with ortho-substitution. This molecular packing-dependent emission afforded crucial information to deeply understand the intrinsic mechanism of different emission forms and the possible packing-function relationship. With the incorporation of solid-state 13 C NMR spectra of single crystals, as well as the analysis of crystal structures, the preferred packing modes for ML and/or RTP were investigated in detail, which can guide the reasonable design of organic molecules with special light-emission properties.

Acylated homoserine lactone (AHL)-mediated quorum sensing (QS) is ecologically important in multi-species systems in laboratory-scale studies; however, little is known about QS in the biofilm formation process in full-scale wastewater treatment plants, which is driven by multiple environmental variables. Here, a model integrated fixed-film-activated sludge system was employed in full-scale municipal wastewater treatment plant to investigate the AHL distribution during the biofilm development process in response to variable environmental factors. The whole biofilm development process can be divided into three phases: initial biofilm attachment process (week 1 to 3), biofilm development and mature phase (week 4 to 6), and biofilm detachment and reformation process (week 7 to 17). N-decanoyl-DL-homoserine lactone (C10-HSL) and N-dodecanoyl-DL-homoserine lactone (C12-HSL) presented high concentrations during the biofilm formation process, which was closely related with the biofilm initial attachment process. The AHL concentration in biofilms was higher than in activated sludge. During the initial attachment process, tryptophan and protein-like substances related to biological substance were strongly positively correlated with all detected AHL concentrations (p 0.05). Three environmental variables (total nitrogen, pH, and Na

The properties of geographical phenomena vary with changes in the scale of measurement. The information observed at one scale often cannot be directly used as information at another scale. Scaling addresses these changes in properties in relation to the scale of measurement, and plays an important role in Earth sciences by providing information at the scale of interest, which may be required for a range of applications, and may be useful for inferring geographical patterns and processes. This paper presents a review of geospatial scaling methods for Earth science data. Based on spatial properties, we propose a methodological framework for scaling addressing upscaling, downscaling and side-scaling. This framework combines scale-independent and scale-dependent properties of geographical variables. It allows treatment of the varying spatial heterogeneity of geographical phenomena, combines spatial autocorrelation and heterogeneity, addresses scale-independent and scale-dependent factors, explores changes in information, incorporates geospatial Earth surface processes and uncertainties, and identifies the optimal scale(s) of models. This study shows that the classification of scaling methods according to various heterogeneities has great potential utility as an underpinning conceptual basis for advances in many Earth science research domains. © 2019 Elsevier B.V.

We evaluated the role of water levels and plant-associated effects on the composition of bacterial communities and the soil organic matter (SOM) composition in wetland ecosystem. Soil (0–15 cm) associated with Phragmites communis, Triarrhena lutarioriparia, Carex cinerascens, and Zizania latifolia was sampled in different water levels (as proxied by sampling time) to analyze soil SOM composition via diffuse reflectance infrared Fourier transform spectroscopy in the mid-infrared range analysis and to analyze soil bacterial communities by high-throughput 16S rRNA gene sequencing. Soil dominant SOM composition (1623–1635 cm−1 and 3444–2697 cm−1) were obviously influenced by water levels not plant species (p

The Loess Plateau is famous for its water shortages and soil erosion, quantitatively assessing the water conservation function is of great significance to maintain regional ecological security. Zhanghe River Basin with severe water conflicts in eastern Loess Plateau, was selected to investigate the variation characteristics of water conservation. The results showed that water conservation decreased slightly from 1960 to 2016, with a rate of 1.1 × 108 m3/10a. The mean annual water conservation (MAWC) is 31.46 × 108 m3, and accounted for 32% of the precipitation. The spatial pattern of water conservation and land use type were significantly correlated: More water resources (>213 mm) were conserved in the north hilly region with high vegetation coverage, while water resources were less (

In this study, based on one-step hydrothermal method, boron nitride nanosheets (BNNs) and MIL-53(Fe) composites (BNFe-X) were successfully prepared and the catalytic performance of BNFe-X on persulfate (PS) activation for ibuprofen (IBP) photodegradation was investigated. The introduction of BNNs changed the morphology of MIL-53(Fe) to be a unique prism-like structure and enhanced the degradation efficiency of IBP, which followed the pseudo-first-order rate kinetics. Among the prepared composites, BNFe-3 (3% BNNs) exhibited the highest IBP degradation activity and possessed strong stability after four cycles. Over 99% IBP removal was achieved at the irradiation time of 60 min. The promoted decomposition rate of IBP could be ascribed to be the activation of PS and the enhanced electrons transfer efficiency between BNNs and MIL-53(Fe). The scavenger studies and electron spin-resonance spectroscopy (ESR) demonstrated the generation of SO2 -, OH and O2 -, and all these radicals had the different contributions in IBP degradation. Based on the LC-MS-MS and TOC results, the possible decomposition pathways of IBP in BNFe-3/PS system were proposed. This work suggested that the BNNs/Fe-based MOFs composites and PS system had great potential in organic pollutants degradation in aqueous solution.

Given the limitations of current approaches for disease relative risk mapping, it is necessary to develop a comprehensive mapping method not only to simultaneously downscale various epidemiologic indicators, but also to be suitable for different disease outcomes. We proposed a three-step progressive statistical method, named disease relative risk downscaling (DRRD) model, to localize different spatial epidemiologic relative risk indicators for disease mapping, and applied it to the real world hand, foot, and mouth disease (HFMD) occurrence data over Mainland China. First, to generate a spatially complete crude risk map for disease binary variable, we employed ordinary and spatial logistic regression models under Bayesian hierarchical modeling framework to estimate county-level HFMD occurrence probabilities. Cross-validation showed that spatial logistic regression (average prediction accuracy: 80.68%) outperformed ordinary logistic regression (69.75%), indicating the effectiveness of incorporating spatial autocorrelation effect in modeling. Second, for the sake of designing a suitable spatial case–control study, we took spatial stratified heterogeneity impact expressed as Chinese seven geographical divisions into consideration. Third, for generating different types of disease relative risk maps, we proposed local-scale formulas for calculating three spatial epidemiologic indicators, i.e., spatial odds ratio, spatial risk ratio, and spatial attributable risk. The immediate achievement of this study is constructing a series of national disease relative risk maps for China’s county-level HFMD interventions. The new DRRD model provides a more convenient and easily extended way for assessing local-scale relative risks in spatial and environmental epidemiology, as well as broader risk assessment sciences.

The Huai River basin (located in eastern China) has a population of 180 million and has the highest risk of esophageal cancer (EC) mortality in China. Some studies found that contaminants in drinking water are a major risk factor for cancers of the digestive system. However, the effect of water pollution in the historical period on the current EC mortality remains unclear. Data were collected on the EC mortality rate in 2004 in the Huai River basin in 11 counties, and data on the surface water quality in the region from 1987 to 2004 were used. The Pearson correlation and the GeoDetector q-statistic were employed to explore the association between water pollution and the EC mortality rate in different lag periods, from linear and nonlinear perspectives, respectively. The study showed apparently spatial heterogeneity of the EC mortality rate in the region. The EC mortality rate downstream is significantly higher than that in other regions; in the midstream, the region north of the mainstream has a lower average mortality rate than that south of the area. Upstream, the region north of the mainstream has a higher mortality rate than that in the southern area. The spatial pattern was formed under the influence of water pollution in the historical period. 1996, 1997, and 1998 have the strongest linear or nonlinear effect on the EC mortality rate in 2004, in which the Pearson correlation coefficient and the q-statistic were the highest, 0.79 and 0.89, respectively. Rapid industrialization in the past 20 years has caused environmental problems and poses related health risks. The study indicated that the current EC mortality rate was mainly caused by water pollution from the previous 8 years. The findings provide knowledge about the lag time for pollution effects on the EC mortality rate, and can contribute to the controlling and preventing esophageal cancer.

Nitrogen is one of the most significant pollutants in the Yangtze River estuary (YRE), China. Reliable estimation of nitrogen concentration in the water is crucial for assessment of the water quality of the estuary. Because ocean fronts exist in the YRE, which divide water masses into different regions, it is necessary to account for the heterogeneity of the water surface when predicting nitrogen concentrations. A new geostatistical method, called spatiotemporal point mean of surface with non-homogeneity (ST-PMSN), is proposed to model the non-stationary spatiotemporal random process of nitrogen concentrations between 2004 and 2013 in the YRE. The method considers the spatiotemporal correlation of surface water nitrogen and uses information from both sides of a boundary for heterogeneous water masses. Comparing with several other interpolating methods, including spatial ordinary kriging (OK), stratified ordinary kriging (SOK), point mean of surface with non-homogeneity (P-MSN), spatiotemporal ordinary kriging (STK), and stratified spatiotemporal ordinary kriging (SSTK), the cross-validation results show that ST-PMSN has the highest accuracy, followed by SSTK, STK, P-MSN, SOK, and OK in descending order. ST-PMSN is therefore demonstrated to be effective in estimating the nitrogen pollutant concentrations in a stratified estuary. According to interpolated nitrogen concentrations in the YRE, water quality has generally deteriorated-with fluctuations-from 2004 to 2013. The average annual reduction in area of water quality of Grades I and II from 2004 to 2013 was 1.10%. At the same time, the average annual increase in area of water quality of Grades III and IV was 0.89% and that of Grade V was 0.21%. The results of this study provide a new and more accurate interpolating method for assessing the pollutant concentration in the marine and offers guidance for more precise classification of water quality in the YRE.

Heavy metal pollution in soil has become a prominent problem affecting agricultural security and ecological health. Hyperspectral remote sensing is used as a rapid method to predict soil heavy metal concentrations. The processing of spectral data and the variables of the estimated model has an important impact on the predictive model of soil heavy metal elements. In this paper, smoothed and resampled spectral reflections are preprocessed by using three preprocessing methods, namely, standard normal variate (SNV), multiplication scatter correlation (MSC) and normalization (NOR). Then, first and second order differential (FD and SD, respectively) and absorbance transformation (AT) are performed. Based on the adsorption and retention of heavy metals by various soil components, the relevant spectral bands are extracted as modeling variables. An extreme learning machine algorithm (ELM) is used to establish the model, and the effects of different factors on the model are compared. Results show that the combination of the three preprocessing methods (SNV, MSC and NOR) with spectral transformation can enhance the stability and predictive ability of the resulting model. The combination of SNV and FD can predict the contents of Cr, Ni and Pb. The R2 of the model is 0.85, 0.87 and 0.80 respectively. The optimal model of Cu is derived from the combination of NOR and SD (R2 = 0.84), and the spectral responses of soil Cr, Ni, Cu and Pb, are closely related to clay mineral-related and organic matter-related bands. The model established by the clay-related bands enhances the stability of the prediction of Ni content, and the RPD value was increased from 2.46 to 2.72 compared with the full-band model. The combination of bands associated with organic matter and clay minerals can accurately predict the content of Cr and Cu in soil; indeed, the predict model R2 for these elements reaches 0.88. Accurate prediction of soil Pb by the full-band model indicates that the Pb concentration in the study area is related to a various of soil chemical components. The prediction effects of the four heavy metal elements show the order Cr > Cu > Ni > Pb. The results of the current study complement the theoretical basis for estimating the heavy metal content of soil by hyperspectral spectroscopy, and provide important insights into the application of hyperspectral remote sensing to monitor other heavy metals.

In this paper, we study a reaction-diffusion system with prey taxis which models the dynamics of a two-predator-one-prey ecosystem in which the predators collaboratively take advantage of the prey's strategy. The global existence and boundedness of solutions of the system in bounded domains of arbitrary spatial dimension and small prey-taxis sensitivity coefficients are proved. It is also shown that such prey-taxis qualitatively affect the stability of coexistence steady state solutions in some cases, and the emergence of forceful prey-taxis will enhance the spatial patterns.

This study examines the changes in physical and mechanical properties of acrylonitrile butadiene styrene (ABS) when manufactured using fused filament fabrication (FFF) 3D printing across multiple recycling phases. Tests were carried out initially using virgin ABS, which subsequently underwent two successive closed-loop filament extrusion and 3D printing phases. For each endpoint manufacturing phase, samples were examined to monitor the changes in thermal characteristics, mechanical properties, and polymer degradation. It was found that there was a series of physical changes of the polymer, which resulted in reduced melt flow, increased glass transition temperature, and the generation of carbonyl groups, which may be attributed to the thermal oxidative breakdown of both styrene acrylonitrile (SAN) and butadiene components of ABS. The recycled polymer also showed a reduction in both tensile and compressive strengths compared to the virgin material. However, compared to one-time recycled ABS, two-times recycled ABS showed increased strength, implying that increased recycle state of the polymer may be advantageous with respect to mechanical properties and potential manufacturing applications. This study ultimately demonstrates the potential to leverage additive manufacturing (AM) toward a closed-loop manufacturing paradigm by using waste ABS across several life cycles.

Soil moisture restricts the ecological restoration in karst, but studies on soil moisture storage (SMS) in karst are lacking. Thus, this study analyzed the characteristics of SMS in the karst area ...

Variations in cutting forces significantly influence the tool wear and part quality in machining high-volume SiC-particle-reinforced aluminum matrix (SiCp/Al) composites. Properties of the reinforcement SiC particles, such as size and volume fraction, contribute to the change in the cutting forces. This paper presents a cutting force model based on the geometrical and mechanical nature of the tool and workpiece, considering the effect of the SiC reinforcement particles. The cutting force is predicted as three components (Fz, Fx, and Fy) and the resultant cutting force Fτs. The cutting force was considered to generate three deformed zones: (a) shear deformed zone, (b) friction deformed zone on the chip–tool interface, (c) plow deformed zone. The effect of SiC reinforcement particles on friction deformed zone is analyzed emphatically. The friction force from friction deformed zone was obtained by calculating the sliding friction force and rolling friction force. To verify the feasibility and validity of the predicted model of cutting force, cutting experiments were performed with different combinations of cutting speed, feed rate, depth of cut, and tool nose radius. The predicted cutting force values demonstrate good agreement with the measured experimental cutting force values in most cutting conditions. The average percentages of the prediction error were 1.93%, 6.20%, and 10.48% for the Fz, Fx, and Fy components, respectively, thus proving the validity and accuracy of the predicted model of cutting forces.

To investigate the morphology and crystalline structure effect on the oxygen reduction reaction (ORR) electrocatalytic, in this work, α-MnO 2 nanowires, α-MnO2 nanorods , β-MnO 2 nanowires and β-MnO2 nanorods have been successfully synthesized via a hydrothermal process, and their microstructures and electrocatalytic activities were investigated for the ORR. Among the four different types of one-dimension (1D) MnO2, the α-MnO2 nanowires exhibited significantly larger electrocatalytic property than the others, which may contribute to the special crystalline structure and larger specific surface area.

Catalytic lanthanum ions (La3+), beneficial for fast dissociative adsorption of hydrogen on its surface, were chosen and introduced into SnO2 nanofibers with different atomic molar ratio to Sn (AMR: 0.5%, 1.0% and 3%) via electrospinning and calcination technique. The sensitivity of La SnO2 metastable solid solution nanofibers (LSMSSNs) for H2 detection is 9.9 against 100 ppm H2 at 300 °C, which is 2.5 times and 1.6 times higher than that of SnO2 nanofibers and La2O3@SnO2 p-n heterojunction nanofibers (LSPNHNs), respectively. More importantly, LSMSSNs achieved both rapid response and recovery behavior of ∼ 1s, long range detectable linearity from 1000 to 25,000 p.m. against H2 and good selectivity towards ethanol, toluene, carbon monoxide and butane, which is very useful for the practical application. A plausible sensing mechanism based on p-type La3+ doping has been established and the relationship with La2O3@SnO2 p-n heterojunction has been investigated. This work provides a basis for understanding and optimizing the high sensitive metal oxide based gas sensors.

In this work, an advanced Rh/CeO2–ZrO2 (Rh/CZ) three-way catalyst was synthesized with the assistance of monoethanolamine. Compared with conventional Rh/CZ, the dispersion and oxidation state of Rh species, as well as the hydrothermal aging resistance are remarkably modified. That is, upon aging treatment, conventional Rh/CZ undergoes severe agglomeration of Rh species and formation of large amount of reduction-resistive RhO2, resulting in serious catalyst deactivation. Fortunately, after the introduction of monoethanolamine, the sintering of Rh species and transformation into inactive RhO2 upon aging are effectively suppressed. Consequently, improved reducibility and advanced three-way catalytic activity are achieved for the modified catalyst.

The aim of this study was to better understand the inflection point of RT and BSTs and measure different body surface temperatures (BSTs) under different temperature-humidity index (THI) conditions. A total of 488 Holstein dairy cows were chosen to manually measure rectal temperature (RT) and BSTs including left side of eye, ear, cheek, forehead, flank, rump, fore udder, and rear udder by infrared thermography for 14 times. Those measurements included six times under high THI (THI > 78), three times under moderate THI (72 ≤ THI ≤ 78), and five times under low THI (THI

Background Pediatric hand, foot, and mouth disease (HFMD) has generally been found to be associated with climate. However, knowledge about how this association varies spatiotemporally is very limited, especially when considering the influence of local socioeconomic conditions. This study aims to identify multi-sourced HFMD environmental factors and further quantify the spatiotemporal nonstationary effects of various climate factors on HFMD occurrence. Methods We propose an innovative method, named spatiotemporally varying coefficients (STVC) model, under the Bayesian hierarchical modeling framework, for exploring both spatial and temporal nonstationary effects in climate covariates, after controlling for socioeconomic effects. We use data of monthly county-level HFMD occurrence and data of related climate and socioeconomic variables in Sichuan, China from 2009 to 2011 for our experiments. Results Cross-validation experiments showed that the STVC model achieved the best average prediction accuracy (81.98%), compared with ordinary (68.27%), temporal (72.34%), spatial (75.99%) and spatiotemporal (77.60%) ecological models. The STVC model also outperformed these models in the Bayesian model evaluation. In this study, the STVC model was able to spatialize the risk indicator odds ratio (OR) into local ORs to represent spatial and temporal varying disease-climate relationships. We detected local temporal nonlinear seasonal trends and spatial hot spots for both disease occurrence and disease-climate associations over 36 months in Sichuan, China. Among the six representative climate variables, temperature (OR = 2.59), relative humidity (OR = 1.35), and wind speed (OR = 0.65) were not only overall related to the increase of HFMD occurrence, but also demonstrated spatiotemporal variations in their local associations with HFMD. Conclusion Our findings show that county-level HFMD interventions may need to consider varying local-scale spatial and temporal disease-climate relationships. Our proposed Bayesian STVC model can capture spatiotemporal nonstationary exposure-response relationships for detailed exposure assessments and advanced risk mapping, and offers new insights to broader environmental science and spatial statistics.

In this work, we report that the high performance of SnTe could be realized by enhancing electrical transport properties (power factor) and reducing thermal conductivity through stepwisely introducing elements of Sb, In and Se. We found that Sb and In co-doping can enhance Seebeck coefficients in the broad temperature range via optimizing carrier density and introducing resonant state, respectively. Moreover, nanostructures could be formed when the Sb content beyond the solubility limit in SnTe matrix, which coupled with point defects from In and Se alloying result in a very low (lattice) thermal conductivity through the enhanced phonon scattering from defects and grain boundaries. A peak ZT ∼1.0 at 923 K can be achieved with the enhanced power factor and reduced thermal conductivity. Accordingly, the average ZT value increases from ∼0.20 for undoped SnTe to ∼ 0.60 for multiple-doped SnTe (Sn0.823Sb0.17In0.007Te0.98Se0.02) over 300–923 K, generating a high calculated conversion efficiency ∼ 11%. Present results indicate the high performance of SnTe can be obtained through stepwisely optimizing strategy in both electrical and thermal transport properties.

PbSe is an alternative of the well-known moderate-temperature thermoelectric material PbTe, and has attracted much attention because of its advantages of high earth-abundance and low price of Se compared with Te. To enhance the thermoelectric performance of PbSe, its several shortcomings should be overcome, such as poor electrical conductivity, small Seebeck coefficient and bipolar thermal conductivity. Simultaneously improving these properties is a big challenge in the thermoelectric community. In this work, we successfully addressed these problems with PbSe by introducing just one component, CdSe, which has a similar crystal structure and larger band gap compared to PbSe. The introduction of CdSe realizes four positive effects: (1) improving the effective mass through flattening the conduction band; (2) decreasing the lattice thermal conductivity enormously by introducing hierarchical sub-nano defects; (3) keeping a high carrier mobility due to the nanostructure-free matrix; (4) suppressing the bipolar thermal conductivity via enlarging the band gap of PbSe. Due to all the above synergistically optimized electrical and thermal transport properties, a superior ZT value of ∼1.4 and ZTave of ∼0.7 are achieved in n-type PbSe through CdSe alloying, and the calculated conversion efficiency can reach 10.5%. Our results indicate that PbSe is a robust candidate for medium-temperature thermoelectric applications.

A nagging problem for the decompostion of photocatalyst organic carrier can be expected to be resolved by shielding effect from our yolk-porous shell nanospheres. The nanospheres were synthesized by a facile strategy: polyporrole (PPy) and silver were deposited together on TiO2 by chemical oxidative polymerization; then PPy/Ag-coated TiO2 nanoparticles were encapsulated in silicon dioxide (SiO2) shell with polyethylene glycol (PEG) as a pore-forming agent via sol-gel method based on hydrolysis of tetraethyl orthosilicate (TEOS). After removing intermediary PPy between yolk and shell by calcination and washing off PEG in shell, yolk-porous shell (SiO2@void@Ag/TiO2) nanospheres were formed. The voids in SiO2@void@Ag/TiO2 can serve as photocatalytic reactors. The channels in porous shell at outer layer provide passages for light transmission, dye molecule accessing and degradants out. More importantly, the euphotic and porous shell exhibited an impressive protection to organic carrier, lest unfavorable decomposition occurred. Yolk-porous shell nanospheres showed commendable performance with >99.5% of dye removal efficiency under 3 h visible light irradiation, higher than pristine TiO2 and Ag/TiO2 nanoparticles, due to the synergy effect of robust adsorption capacity and photocatalysis. Our work could provide a good strategy for developing novel carrier-based photocatalysts for environmental remediation application, which can be readily extended to the combination of other nanophotocatalysts and organic carriers for enhancing sustainable photocatalytic performance.

ZIF-67@Co-LDH yolk–shell heterostructures are successfully synthesized by successive increase in Co2+ concentration in the methanolic solution of Co2+ and 2-methylimidazole (Hmim). This is mainly attributed to the slight difference in thermodynamic stability between ZIF-67 and Co-LDHs, accounting for the selective generation of Co-LDHs at a high molar ratio of Co2+ to Hmim. Co-LDH sheet assembled hydrophilic shells with mesoporous structures can control guest species shuttling between their interiors and exteriors, improving ZIF-67 stability and maintaining its reactivity as well in humid environments. Finally, hierarchical porous structures with high specific surface area are used to load the drug molecule model of rhodamine 6G to study drug delivery. The micro-/meso-porous structural ZIF-67@Co-LDH yolk–shell spheres exhibit a higher loading amount and longer release time compared to ZIF-67 nanocrystals or Co-LDH hollow spheres alone.

This study presents a new approach to imparting the combined functionalities of superhydrophobicity, UV protection and personal thermal management via the photothermal effect to cotton fabrics. Surface modification of fabrics was carried out by applying coatings containing natural melanin (NM) particles extracted from yak hair and fluorine-free polydimethylsiloxane (PDMS) polymer via a dip-pad-dry-cure process. Different concentrations of NM particles were used in the coatings and the roles of each ingredient in achieving the desired functionalities were investigated. In addition, the relationship between NM content and the resultant durability of the coatings was explored based on the variations in superhydrophobicity, UV protection, photothermal performance, and color strength of the fabrics. The results demonstrated that the non-fluorinated NM/PDMS coatings were highly effective in developing a superhydrophobic cotton fabric with a water contact angle of 164°. The NM-coated fabrics provided a rapid heating effect under near-infrared light and their temperature increased to 38.4-45.3 °C, which was up to 14.7 °C higher than that of pristine cotton. Furthermore, the application of NM particles resulted in an excellent UV protection performance and generated the UV protection factor level of 198.48 on cotton fabrics. Finally, the coated fabrics were highly breathable and showed high stability against 1000 abrasion cycles, 5 accelerated launderings, and 70 h UV irradiation. These findings provide new pathways in the development of future functional textiles using user-friendly and biocompatible ingredients.