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Enrofloxacin (ENR) residue is harmful to humans and the ecosystem. Therefore, it is necessary to develop a method for the detection of ENR residues in food. Herein, we have prepared novel biomass-derived carbon dots (BCDs) by a one-step hydrothermal method to detect ENR. The precursor material is cicada slough, which is one of the traditional crude drugs. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results confirmed the formation of BCDs. The average particle size of the prepared BCDs is 19.6 ± 0.2 nm, and the maximum excitation/emission wavelength is 355/436 nm. Under the optimal conditions, the detection linear of ENR ranged from 0.13 to 16.67 µM, and the detection limit was 0.069 µM. According to the experimental results, it can be applied in the detection of ENR in aquatic products with a good recovery rate (88.6%–104.7%), demonstrating its potential in detecting ENR in aquatic products.

Symbiotic radio (SR) and reconfigurable intelligent surface (RIS) can serve as a complementary technique for each other regarding spectrum efficiency and energy efficiency (EE) improvements. In this paper, we investigate a RIS-aided multiple-input single-output SR system with multiple backscatter devices (BDs). In particular, an EE-based maximization resource allocation problem is formulated by jointly optimizing the passive beamforming vector of the RIS, the active beamforming vector of the primary transmitter (PT), and the reflection coefficient of each BD under multiple constraints, including the minimum rate of each user, the maximum transmit power of the PT, and the minimum harvested energy of each BD. To solve the non-convex problem, a Dinkelbach-based block coordinate descent algorithm is developed to obtain the sub-optimal solution. Numerical results verify that the proposed algorithm achieves two times more than the traditional algorithms in terms of system EE.

A new type of lubricating material (BTA-P4444-Lig) was synthesized by combining lignin with tetrabutylphosphorus and benzotriazole. The tribological properties, corrosion resistance, and anti-oxidation properties of BTA-P4444-Lig as a lubricant were investigated. The lubricating material exhibits excellent friction reduction and wear resistance, as well as good thermal stability and excellent oxidation resistance. Mechanistic analysis reveals that the active elements N and P in the lubricating material react with the metal substrate, and the reaction film effectively blocks direct contact between the friction pairs, affording excellent friction reduction and wear resistance. At the same time, the phenolic hydroxyl group in lignin reacts with oxygen free radicals to form a resonance-stable semi-quinone free radical, which interrupts the chain reaction and affords good anti-oxidant activity.

Enhancing the output performance of piezoelectric nanogenerators (PENG) is crucial for the timely realization of self-powered IoT sensor clusters. Currently, conventional methods for retrofitting PENG lack universality. Therefore, this paper proposes a novel negative Poisson's ratio effect to effectively accelerate and enhance charge separation, increasing the output power from 0.6mW to 4.0mW, a 6.7-fold increase, and broadening the bandwidth from 0.7Hz to 1.8Hz, a 2.6-fold improvement. The negative Poisson's ratio effect is a mechanical metamaterial property that can be served as a universal method to enhance the performance of all beam-type PENGs. Furthermore, the metamaterial PENG (MM-PENG), optimized by a genetic algorithm for multiple parameters, demonstrates a power density of 36.35 μW/mm3, far exceeding previously reported conventional PENGs (C-PENG) with plain substrate. Finally, the practical application of MM-PENG confirms its faster power supply rate compared to C-PENGs. This work presents a universally applicable and straightforward method for enhancing the performance of PENG.

Objective

Agricultural activities, including stock-farming, planting industry, and fish aquaculture, can affect the physicochemical and biological characters of freshwaterlakes. However, the effects of pollution producing by agricultural activities on microbial ecosystem of lakes remain unclear. Hence, in this work, we selected Honghu Lake as a typical lake that is influenced by agriculture activities. We collected water and sediment samples from 18 sites, which span a wide range of areas from impacted and less-impacted areas. We performed a geospatial analysis on the composition of microbial communitiesassociated with physicochemical properties and antibiotic pollution of samples. The co-occurrence networks of water and sediment were also built and analyzed. Our results showed that the microbial communities of impacted and less-impacted samples of water were largely driven by the concentrations of TN, TP, NO3−-N, and NO2−-N, while those of sediment were affected by the concentrations of Sed-OM and Sed-TN. Antibioticshave also played important roles in shaping these microbial communities: the concentrations of oxytetracycline and tetracycline clearly reflected the variance in taxonomic diversity and predicted functional diversity between impacted and less-impacted sites in water and sediment samples, respectively. Furthermore, for samples from both water and sediment, large differences of network topology structures between impacted and less-impacted were also observed. Our results provide compelling evidence that the microbial community can be used as a sentinel of eutrophication and antibiotics pollution risk associated with agricultural activity; and that proper monitoring of this environment is vital to maintain a sustainable environment in Honghu Lake.

Agricultural activities, including stock-farming, planting industry, and fish aquaculture, can affect the physicochemical and biological characters of freshwaterlakes. However, the effects of pollution producing by agricultural activities on microbial ecosystem of lakes remain unclear. Hence, in this work, we selected Honghu Lake as a typical lake that is influenced by agriculture activities. We collected water and sediment samples from 18 sites, which span a wide range of areas from impacted and less-impacted areas. We performed a geospatial analysis on the composition of microbial communitiesassociated with physicochemical properties and antibiotic pollution of samples. The co-occurrence networks of water and sediment were also built and analyzed. Our results showed that the microbial communities of impacted and less-impacted samples of water were largely driven by the concentrations of TN, TP, NO3−-N, and NO2−-N, while those of sediment were affected by the concentrations of Sed-OM and Sed-TN. Antibioticshave also played important roles in shaping these microbial communities: the concentrations of oxytetracycline and tetracycline clearly reflected the variance in taxonomic diversity and predicted functional diversity between impacted and less-impacted sites in water and sediment samples, respectively. Furthermore, for samples from both water and sediment, large differences of network topology structures between impacted and less-impacted were also observed. Our results provide compelling evidence that the microbial community can be used as a sentinel of eutrophication and antibiotics pollution risk associated with agricultural activity; and that proper monitoring of this environment is vital to maintain a sustainable environment in Honghu Lake.

We have developed a Pd–graphene nanocomposite for hydrogen storage. The spherically shaped Pd nanoparticles of 5–45 nm in size are homogeneously distributed over the graphene matrix. This new hydrogen storage system has favorable features like desirable hydrogen storage capacity, ambient conditions of hydrogen uptake, and low temperature of hydrogen release. At a hydrogen charging pressure of 50 bar, the material could yield a gravimetric density of 6.7 wt % in the 1% Pd/graphene nanocomposite. As we increased the applied pressure to 60 bar, the hydrogen uptake capacity reached 8.67 wt % in the 1% Pd/graphene nanocomposite and 7.16 wt % in the 5% Pd/graphene nanocomposite. This system allows storage of hydrogen in amounts that exceed the capacity of the gravimetric target announced by the U.S. Department of Energy (DOE).

AbstractThe aim of this study was to prepare a cross-linked cerium(III)-loaded alginate bead (denoted as SA-Ca-Ce) and to apply it to remove phosphate from aqueous solution. The adsorption behaviors were investigated by the batch experiments at various experimental parameters including contact time, initial phosphate concentration, solution pH, temperature, and coexisting anions. The results showed that the Langmuir model is more suitable than the Freundlich model for well elucidation of the experimental data, and the maximum adsorption capacity is calculated to be 41.39 mg/g at 318 K. The adsorption of phosphate, which followed pseudo-second-order kinetics, is a chemisorption process. The phosphate adsorption had a slight decrease with the increasing of pH. The coexistence of other anions in solutions has an adverse effect on phosphate adsorption with the extent following the order:  >  > Cl−. The phosphate adsorption mechanism was also investigated by scanning electron microscopy, Fourier transform infrareds spectroscopy. The electrostatic interactions and Lewis acid ligand were manifested to be two main mechanisms for phosphate adsorption onto SA-Ca-Ce. All the results indicated that the SA-Ca-Ce has a considerable potential for the phosphate removal from contaminated waters.

The aim of this study was to prepare a cross-linked cerium(III)-loaded alginate bead (denoted as SA-Ca-Ce) and to apply it to remove phosphate from aqueous solution. The adsorption behaviors were investigated by the batch experiments at various experimental parameters including contact time, initial phosphate concentration, solution pH, temperature, and coexisting anions. The results showed that the Langmuir model is more suitable than the Freundlich model for well elucidation of the experimental data, and the maximum adsorption capacity is calculated to be 41.39 mg/g at 318 K. The adsorption of phosphate, which followed pseudo-second-order kinetics, is a chemisorption process. The phosphate adsorption had a slight decrease with the increasing of pH. The coexistence of other anions in solutions has an adverse effect on phosphate adsorption with the extent following the order: HCO3- > SO42- > Cl−. The phosphate adsorption mechanism was also investigated by scanning electron microscopy, Fourier transform infrareds spectroscopy. The electrostatic interactions and Lewis acid ligand were manifested to be two main mechanisms for phosphate adsorption onto SA-Ca-Ce. All the results indicated that the SA-Ca-Ce has a considerable potential for the phosphate removal from contaminated waters.

We have designed a Ni–graphene composite for hydrogen storage with Ni nanoparticles of 10 nm in size, uniformly dispersed over a graphene substrate. This system exhibits attractive features like high gravimetric density, ambient conditions, and low activation temperature for hydrogen release. When charged at room temperature and an atmospheric hydrogen pressure of 1 bar, it could yield a hydrogen capacity of 0.14 wt %. When hydrogen pressure increased to 60 bar, the sorbent had a hydrogen gravimetric density of 1.18 wt %. The hydrogen release could occur at an operating temperature below 150 °C and completes at 250 °C.

Fabrication of self-healing anticorrosion coatings has attracted attention as it has the ability to extend the service life and prevent the substrate from corrosive attack. However, a coating system with a rapid self-healing ability and an improved corrosion resistance is rarely reported. In this work, we developed a self-healing anticorrosion coating on a magnesium alloy (AZ31). The coating comprises a cerium-based conversion layer, a graphene oxide layer, and a branched poly(ethylene imine) (PEI)/poly(acrylic acid) (PAA) multilayer. We incorporated the graphene oxide as corrosion inhibitors and used the PEI/PAA multilayers to provide the self-healing ability to the coating systems. X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the composition of the multilayers, and scanning electron microscopy (SEM) was used to analyze the surface morphology. The electrochemical impedance spectroscopy (EIS) results illustrate the improved corrosion resistance of the coating. The proposed coating also has a rapid self-healing ability in the presence of water.

•Metakaolin-based geopolymer is applied to detoxify and immobilize COPR.•Preferable sodium sulfide addition was determined according to Cr leachability.•The product prepared has a relatively high compressive strength.

Abstract: In this study, the electron effective masses, including longitudinal, transverse, density-of-states and conductivity effective masses, have been systematically investigated in (001), (101) and (111) biaxially strained Si and Si1−x Ge x . It is found that the effect of strain on the longitudinal and transverse masses can be neglected, that the density-of-states masses in (001) and (110) biaxially strained Si and Si1−x Ge x materials decrease significantly with increasing Ge fraction (x), and that the conductivity masses along typical orientations in (001) and (110) strained Si and Si1−x Ge x .are obviously different from those in relaxed Si. The quantitative results obtained from this work may provide valuable theoretical references to understanding strained materials physics and studying conduction channel design related to stress and orientations in the strained devices.

In vertebrates, hematopoiesis occurring in different niches is orchestrated by intrinsic and extrinsic regulators. Previous studies have revealed numerous linear and planar regulatory mechanisms. However, a multi-dimensional transcriptomic atlas of any given hematopoietic organ has not yet been established. Here, we use multiple RNA sequencing (RNA-seq) approaches, including cell type-specific, temporal bulk RNA-seq, in vivoGEO-seq, and single-cell RNA-seq (scRNA-seq), to characterize the detailed spatiotemporal transcriptome during hematopoietic stem and progenitor cell (HSPC) expansion in the caudal hematopoietic tissue (CHT) of zebrafish. Combinatorial expression profiling reveals that, in the CHT niche, HSPCs and their neighboring supporting cells are co-regulated by shared signaling pathways and intrinsic factors, such as integrin signaling and Smchd1. Moreover, scRNA-seq analysis unveils the strong association between cell cycle status and HSPC differentiation. Taken together, we report a global transcriptome landscape that provides valuable insights and a rich resource to understand HSPC expansion in an intact vertebrate hematopoietic organ.