Magnetite (Fe3O4)/carbon (C) composite flowers with an average size of 4–6 μm were prepared through a facile route including a solvothermal approach and a carbon reduction process. The resultant ...Fe3O4/C composites are porous and exhibit a three-dimensional (3D) flower-like morphology with the core–shell Fe3O4@C nanoparticles hybridized by amorphous carbon sheets. The epoxy resin composites containing 50 wt % 3D porous Fe3O4/C composite flowers display an optimal reflection loss (RL) value of −54.6 dB at 5.7 GHz at a thin thickness of 4.27 mm and the effective bandwidth with RL < −10 dB reaches 6.0 GHz at a thickness of 2.1 mm. These enhanced EM wave absorption performances are attributed to the synergistic effects of Fe3O4 and carbon as well as the structural advantages, e.g., three-dimensional structure with large surface area, porous and core–shell structures of Fe3O4/C flowers. These results suggest the 3D porous Fe3O4/C composite flowers designed here can serve as ideal candidates for high-performance EM wave absorption.
A piezoelectric actuator, which is constructed by bonding six pieces of lead zirconate titanate (PZT) ceramic plates on a step aluminum alloy beam, was proposed and tested for the design of a ...small-size rotary driving appratus. Two pieces of PZT ceramic plates bonded in the middle part is used to generate the first bending mode, whereas the other four on the two sides are set for the excitation of the second bending mode; their superimposition can produce elliptical movements on the two ends of the beam, which can rotate a disk-shaped rotor. Compared with the traditional ring-shaped traveling-wave piezoelectric actuator, the proposed actuator has a simpler structure and operating principle; it also gives a new mode for rotary driving. The resonance frequencies of the first and second bending modes were designed to be close at about 21.1 kHz. The maximum no-load speed and torque were tested to be 158 r/min and 0.053 N · m, respectively. The prototype achieved a power density of 19.0 W/kg under a weight of 15.8 g. The proposed combination plan of the first and second bending modes is very suitable for constructing a small-size piezoelectric actuator, which exhibits merits for application in small systems.
The antibiotic sulfamethoxazole (SMX) is a pollutant that is widely distributed in the global water environment.This substance has toxic effects on various aquatic organisms. Previous studies on SMX ...have focused on its acute toxicity towards algae and the changes induced at biological and cellular levels, rather than its biotoxicity and mechanisms at the molecular level. In this study, we investigated the effects of SMX on Scenedesmus obliquus as the model organism by performing transmission electron microscopy and transcriptome sequencing analyses. Exposure to SMX promoted gene expression, resulting in changes to algal cell ultrastructure. The cell walls became blurred, the chloroplast structure was seriously damaged, and the number and volume of mitochondria per cell increased. These changes were related to the inhibition of cell growth, decrease in chlorophyll content, increase in cell membrane permeability, and increased production of reactive oxygen species, which led to increased amounts of the lipid peroxidation product malondialdehyde, and higher activities of antioxidant enzymes. Our results suggest that SMX affects gene expression by influencing non-coding RNA metabolic processes, leading to changes in nuclear structures. Abnormally expressed long non-coding RNAs extensively regulate downstream gene expression through various mechanisms, such as chromatin recombination, thereby promoting tumor occurrence, invasion, and metastasis. This abnormal expression may be an important mechanism underlying the carcinogenic effects of SMX.
•SMX promoted gene expression of S. obliquus cells.•The ultrastructure of algal cells changed and oxidative damage occurred.•SMX affected the photosynthetic function of S. obliquus and inhibited cell growth.
A single-foot linear piezoelectric actuator is proposed in this paper, and a new exciting method for the stepping motion is discussed. The proposed actuator works in the hybrid modes of the second ...horizontal bending vibration and the second vertical bending vibration. Two intermittent sinusoidal signals with a phase difference of 90° are applied on the horizontal and vertical PZT elements, respectively, to obtain a discontinuous elliptical motion at the driving foot, which can move the runner linearly step by step. The structure of a single-foot linear piezoelectric actuator is designed and the mechanism for the linear driving is clarified. Then, modal and transient analyses are carried out by using ANSYS software to get the resonance frequencies of the bending modes and the movement trajectory of the driving foot. Finally, a prototype of the piezoelectric actuator is fabricated, and experiments are carried out. The experiment results show that the displacement resolution, the maximum velocity, and the maximum thrust of the proposed piezoelectric actuator are about 0.21 μm, 827.5 mm/s, and 27 N, respectively.
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•An ecosystem restoration zoning framework based on ecological network is proposed.•Differentiated ecosystem restoration strategies are proposed for ecological zones.•Both ecological ...network and zoning show obvious east-west differentiation.
Ecological network is an important landscape approach for biodiversity and ecosystem conservation. However, the lack of further spatial analysis and ecological zoning makes it difficult to implement ecological conservation and restoration measures based on ecological network. In this study, we proposed a framework for ecological zoning based on ecological network with a case study in Yunnan Province, China. The results showed that the ecological network in the study area was consisted of ecological sources with the total area of 136496.56 km2, 276 ecological corridors with an average length of 41.40 km, and pinchpoints and barriers with an area of 425.54 km2 and 1422.83 km2 respectively. Yunnan Province was divided into five ecological zones based on ecological network. Source protection zone included 153 watersheds, with large area and high connectivity of ecological sources, needing to conserve the original natural ecosystem. Source enhancement zone included 103 watersheds with ecological sources of small area and discrete distribution. Ecological conservation was particularly important in southeast karst regions. Corridor construction zone included 143 watersheds, needing to build dense ecological corridors in an orderly manner. Ecological node restoration zone included 15 watersheds. Key ecological nodes needed restoration to enhance the overall connectivity. Non-ecological network zone needed to be paid attention to local ecological conservation. The zoning framework based on ecological network can help to implement ecological conservation and restoration in light of local conditions.
A novel rhodamine-based turn-on dual-channel Hg2+ sensor with excellent overall performance and new sensing mechanism was reported.
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•New easily prepared rhodamine-based Hg2+ sensor is ...developed.•A The overall performance of the sensor is excellent.•The solid support sensor can monitor Hg2+ in 100% H2O by the naked eye.•A new interaction way between Hg2+and the sensor is proposed.
A novel rhodamine-based colorimetric and fluorescent sensor for Hg2+ was reported. In CH3CN/H2O (1/99, v/v), the sensor showed high selectivity and sensitivity to Hg2+ by an emerging absorption peak at 565nm and a 32-fold fluorescence enhancement at 586nm with vivid color changes. The absorbance and fluorescence maxima increased linearly with the concentration of Hg2+ in the range of 0–90μM. The colorimetric and fluorescent detection limits were 6.36μM and 60.78nM respectively. The sensor could work in a nearly neutral pH span of 6.01–8.57 and exhibited excellent interference immunity and low cytotoxicity. A 1:2 sensor-Hg2+ complex formed with a binding constant of 2.89×108M−2. A new sensing mechanism was proposed. The sensor was successfully applied in real sample assay and living cell imaging. Furthermore, the sensor could be supported in low cost cellulose discs for signaling Hg2+ in 100% aqueous solution.
Cities are commonly recognized as the immediate hinterland of ports and play a crucial role in fostering the sustainable development of ports. Therefore, it is imperative to investigate the influence ...of cities on ports. By employing panel data from 2001 to 2021 for both ports and cities in the Bohai Rim region, this study examines the spatial spillover effect of urban economy on port efficiency using the spatial error model (SEM). The findings show that urban economies have a significant spatial spillover effect on port efficiency, but this effect diminishes across different spatial matrices. In particular, the geographical matrix demonstrates a stronger spatial spillover effect of the urban economy on port efficiency. These research findings help to establish a collaborative mechanism for port-city development and provide useful insights for government management decision-making.
This study assessed the impact of assimilating the Fengyun-4A (FY-4A) Advanced Geosynchronous Radiation Imager (AGRI) observations on the Super Typhoon “In-Fa” event based on the Weather Research and ...Forecasting Data Assimilation (WRFDA) system of the three-dimensional variational data assimilation (3DVAR) method. It was found that the two water vapor channels 9–10 from the full-disk AGRI datasets yield relatively stable results in terms of the track forecast of In-Fa. A new cloud-detection method using a Particle Filter (PF) was firstly employed to remove the cloud-affected observations by identifying the channel’s weighting function. Compared to the other cloud-detection schemes based on the AGRI “Cloud_Binary_Mask” (CLM) products, the PF method is conducive to reducing the track error of typhoon prediction after improving the utilization of observations under clear-sky conditions. Furthermore, the proposed cycling assimilation scheme has a potential positive effect on the intensity forecast of In-Fa. It seems that assimilating the FY-4A AGRI radiance data improves the predictability of Typhoon In-Fa by adjusting the atmospheric environment.
The effects of biodiversity on ecosystem functions have been extensively studied, but little is known about the effects of ecosystem functions on biodiversity. This knowledge is important for ...understanding biodiversity-ecosystem functioning relationships. Desertification reversal is a significant global challenge, but the factors that play key roles in this process remain unclear. Here, using data sampled from areas undergoing desertification reversal, we identify the dominant soil factors that play a role in vegetation recovery with ordinary least squares and structural equation modelling. We found that ecosystem functions related to the cycling of soil carbon (organic C, SOC), nitrogen (total N, TN), and potassium (available K, AK) had the most substantial effects on vegetation recovery. The effects of these ecosystem functions were simultaneously influenced by the soil clay, silt and coarse sand fractions and the soil water content. Our findings suggest that K plays a critical role in ecosystem functioning and is a limiting factor in desertification reversal. Our results provide a scientific basis for desertification reversal. Specifically, we found that plant biodiversity may be regulated by N, phosphorus (P) and K cycling. Collectively, biodiversity may respond to ecosystem functions, the conservation and enhancement of which can promote the recovery of vegetation.
The present study investigated the species level based microbial community and metabolome in corn silage inoculated with or without homofermentative
and heterofermentative
using the PacBio SMRT ...Sequencing and time-of-flight mass spectrometry (GC-TOF/MS). Chopped whole crop corn was treated with (1) deionized water (control), (2)
, or (3)
. The chopped whole crop corn was ensiled in vacuum-sealed polyethylene bags containing 300 g of fresh forge for 90 days, with three replicates for each treatment. The results showed that a total of 979 substances were detected, and 316 different metabolites were identified. Some metabolites with antimicrobial activity were detected in whole crop corn silage, such as catechol, 3-phenyllactic acid, 4-hydroxybenzoic acid, azelaic acid, 3,4-dihydroxybenzoic acid and 4-hydroxycinnamic acid. Catechol, pyrogallol and ferulic acid with antioxidant property, 4-hydroxybutyrate with nervine activity, and linoleic acid with cholesterol lowering effects, were detected in present study. In addition, a flavoring agent of myristic acid and a depression mitigation substance of phenylethylamine were also found in this study. Samples treated with inoculants presented more biofunctional metabolites of organic acids, amino acids and phenolic acids than untreated samples. The
species covered over 98% after ensiling, and were mainly comprised by the
and
. As compared to the control silage, inoculation of
increased the relative abundances of
and
, and a considerable decline in the proportion of
was observed; whereas an obvious decrease in
and increases in
and
were observed in the
inoculated silage. Therefore, inoculation of
and
regulated the microbial composition and metabolome of the corn silage with different behaviors. The present results indicated that profiling of silage microbiome and metabolome might improve our current understanding of the biological process underlying silage formation.
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