As a key candidate technique for fifth-generation (5G) mobile communication systems, non-orthogonal multiple access (NOMA) has attracted considerable attention in the field of wireless communication. ...Successive interference cancellation (SIC) is the main NOMA detection method applied at receivers for both uplink and downlink NOMA transmissions. However, SIC is limited by the receiver complex and error propagation problems. Toward this end, we explore a high-performance, high-efficiency tool-deep learning (DL). In this paper, we propose a learning method that automatically analyzes the channel state information (CSI) of the communication system and detects the original transmit sequences. In contrast to existing SIC schemes, which must search for the optimal order of the channel gain and remove the signal with higher power allocation factor while detecting a signal with a lower power allocation factor, the proposed deep learning method can combine the channel estimation process with recovery of the desired signal suffering from channel distortion and multiuser signal superposition. Extensive performance simulations were conducted for the proposed MIMO-NOMA-DL system, and the results were compared with those of the conventional SIC method. According to our simulation results, the deep learning method can successfully address channel impairment and achieve good detection performance. In contrast to implementing well-designed detection algorithms, MIMO-NOMA-DL searches for the optimal solution via a neural network (NN). Consequently, deep learning is a powerful and effective tool for NOMA signal detection.
Phthalates (phthalic acid esters) have been widely applied as plasticizers. They are ubiquitous contaminants in soils, thereby posing a threat to human health. In this study, ecotoxicological effects ...of three typical PAEs (dimethyl phthalate-DMP, di-n-octyl phthalate-DOP and butyl benzyl phthalate-BBP) were investigated. As a biological indicator, earthworms (Eisenia fetida) were exposed to phthalates at various doses (0, 0.1, 1, 10 and 50 mg/kg) for different times (7, 14, 21, and 28 d). We evaluated the effects of phthalates on reactive oxygen species (ROS) generation, antioxidant enzymes (superoxide dismutase-SOD, peroxidase-POD and catalase-CAT) activities, glutathione S-transferase enzyme (GST) activity, malondialdehyde (MDA) content and DNA damage. Results showed that ROS content increased with increasing phthalates, whereas ROS content generally increased and then decreased with exposure time. However, antioxidant enzymes activities in earthworms displayed different trends. The GST activity in high-dose treatment group was significantly activated. For DMP and DOP, lipid peroxidation mainly occurred between 14 and 28 d, while for BBP, it primarily existed after 7 d and then disappeared after 28 d. Besides, comet assay indicated that there was a dose-response relationship between the DNA damage and phthalate dose, following DMP > DOP > BBP. Given their toxicity, it is important to understand the mechanisms associated with their eco-toxicity and to reduce their adverse impacts on the environment.
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•Phthalates induced oxidative stress and DNA damage in earthworms.•Phthalates enhanced ROS generation and lipid peroxidation, and activated GST.•Different antioxidant enzymes responded differently to DMP, DOP and BBP.•Phthalate-generated DNA damage followed DMP > DOP > BBP.
An ultrasonic-assisted extraction methodology coupled with gas chromatography-mass spectrometer analytical technique was used to determine concentration of phthalic acid esters (PAEs) in typical ...greenhouse soil. The results showed that the developed method has a reliable recovery rate (80.78%–112.89%) and a low detection limit (10
− 4
mg/kg) which met the requirements of residue determination. The analysis of 32 soil samples revealed that except for dimethyl phthalate, the concentration of other five PAEs was detected and followed the sequence di-(2-ethylhcxyl) phthalate > dibutyl phthalate > di-
n
-octyl phthalate > butylbenz phthalate > diethyl phthalate. Σ
6
PAEs concentrations ranged from 136.91 to 1121.74 µg/kg (mean 319.59 µg/kg). PAEs was closely correlated with soil pH and organic matter, but not with cultivation ages which indicates that the increase of cultivation age is not the main reason for the change of soil PAEs concentration.
In the estimation of the direction of arrival (DOA) for interference signals, the direction-finding error of the multiple signal classification (MUSIC) algorithm will increase in the case of multiple ...interferences or when the interfering signal power is weak. In this paper, a space-time conversion MUSIC (STC-MUSIC) algorithm is proposed, and the concept of a focusing parameter is introduced to improve the performance of the DOA estimation. Meanwhile, a method of variable step size peak search is proposed to reduce the amount of calculation of the STC-MUSIC algorithm. The final simulation and experimental results show that the STC-MUSIC algorithm improves the purity of the noise subspace effectively, thus improving the precision and robustness of the DOA estimation for interference signals significantly. In comparison to traditional algorithms, the convergence, stability, root mean square error (RMSE) and other performance characteristics are improved greatly.
•DEHP presented low acute toxicity to adult zebrafish (Danio rerio)•DEHP induced oxidative stress, lipid peroxidation and DNA damage in zebrafish hepatic tissue.•Acetylcholinesterase (AChE) activity ...of zebrafish liver was significantly inhibited after DEHP exposure.•The ecotoxicological risk of adult zebrafish increased with increasing DEHP concentrations.
Di-(2-ethylhexyl) phthalate (DEHP) has become a ubiquitous contaminant in aquatic environments due to its increasing utilization in recent years. Although its environmental risks to aquatic organisms have attracted widespread attention, the ecotoxicological effects and toxic mechanism of DEHP on zebrafish (Danio rerio) liver remain poorly understood. Herein, this study investigated the acute toxicity, oxidative damage, neurotoxicity, and DNA damage of DEHP on zebrafish at the individual, tissue, physiological and biochemical levels. Results showed that no evident lethal effects of DEHP on zebrafish were observed in all testing concentrations. But in the chronic toxicity test (28 days), superoxide dismutase (SOD) and catalase (CAT) activities in zebrafish liver mainly increased during the pre-and mid-exposure experiment and subsequently decreased after 28 days exposure, whereas the acetylcholinesterase (AChE) activities were always inhibited. By comparison, reactive oxygen species (ROS), malondialdehyde (MDA), and glutathione S-transferase (GST) levels generally increased throughout the experiment, indicating that DEHP enhanced oxidative stress lipid peroxidation, and cytotoxicity of zebrafish liver. DEHP induced DNA damage in hepatocyte, which was positively correlated with changes in ROS levels (0.9874 ≥ R2 ≥ 0.7374). Based on the risk assessment results, the integrated biomarker response (IBR) values were positively correlated with the DHEP concentrations, suggesting that higher DHEP concentrations may cause much more serious detrimental effects to zebrafish liver. Overall, this study is of great significance for understanding the ecotoxicity and mechanism of DEHP on zebrafish.
For global navigation satellite system receivers, Kalman filter (KF)-based tracking loops show remarkable advantages in terms of tracking sensitivity and robustness compared with conventional ...tracking loops. However, to improve the tracking sensitivity further, increasing the coherent integration time is necessary, but it is typically limited by the navigation data bit sign transition. Moreover, for standard KF-based tracking receivers, the KF parameters are initialized by the acquired results. However, especially under weak signal conditions, the acquired results have frequency errors that are too large for KF-based tracking to converge rapidly to a steady state. To solve these problems, a two-stage KF-based tracking architecture is proposed to track weaker signals and achieve faster convergence. In the first stage, coarse tracking refines the acquired results and achieves bit synchronization. Then, in the second stage, fine tracking initializes the KF-based tracking by using the coarse tracking results and extends the coherent integration time without the bit sign transition limitation. This architecture not only utilizes the self-tuning technique of the KF to improve the tracking sensitivity, but also adopts the two-stage to reduce the convergence time of the KF-based tracking. Simulation results demonstrate that the proposed method outperforms conventional tracking techniques in terms of tracking sensitivity. Furthermore, the proposed method is compared with the standard KF-based tracking approach, proving that the proposed method converges more rapidly.
Di-(2-ethylhcxyl) phthalate (DEHP) is applied as plasticizer, which results in the pollution of environment. In this study, the effects of DEHP on soil microbial functions, structure and genetic ...diversity were investigated. The concentration of DEHP in the soil were 0, 0.1, 1, 10 and 50 mg/kg, and the experimental period were 28 days. DEHP reduced the quantity, abundance, species dominance and homogeneity of soil microbes during the first 14 days. In addition, microbial utilization efficiency of carbon (carbohydrates, aliphatics, amino acids, metabolites) was impacted after 28 days, though the effects gradually weakened. Based on denaturing gradient gel electrophoresis and clone library analysis, in the presence of DEHP, the dominant microbes in the DEHP-contaminated soil were
Sphingomonas
and
Bacillus
, which belonged to the
Acidobacteria
and
Proteobacteriav
, respectively. With 0.1 or 1 mg/kg of DEHP, the relative abundances of
Acidobacteria
were higher, and with 10 or 50 mg/kg of DEHP, the relative abundances of
Proteobacteria
were higher.
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•At 298 K, the SnS monolayer exhibit good sensitivity for detecting As and Pb and is reused at 598 K.•SnS monolayers can detect Cd in low concentration and desorb quickly at room ...temperature.•SnS monolayers can detect Hg in high concentrations.•The SnS monolayer is difficult to desorb following adsorption of Cr or Ni due to chemisorption.
Monitoring heavy metals helps prevent heavy metal contamination from affecting human health. However, existing monitoring technologies encounter challenges in real-time detection. Using density functional theory and non-equilibrium Green's function method, sensing capacities of SnS monolayer towards heavy metals are analyzed by adsorption energy, charge transfer, energy band structure, the density of states, differential charge density, recovery time, and transport performance. SnS monolayers exhibit high selectivity and good sensitivity of 13527% and 368860% for detecting As and Pb at the coverage of 1, respectively. With recovery times of 2.99 s for As and 76.44 s for Pb at 598 K, SnS monolayers can detect As or Pb at ambient temperature and be reused at high temperatures. SnS monolayers can selectively detect As and Pb through their response peaks at different bias voltages. SnS monolayers can detect Cd with a sensitivity of 442% in the concentration as low as coverage 1, when desorb at a recovery time of 31.2 μs at 298 K, showing strong potential for ambient temperature sensors for Cd. SnS monolayers require Hg in high concentration, as high as coverage of more than 7, to reach the detection limit. The highest sensitivity of SnS monolayers towards Hg is 326% at the condition of a 0.6-V bias voltage and 8 coverage. Overall, our research provides fresh insight into low-cost, environmentally friendly materials for online heavy metal detection.
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•SnSe monolayers are sensitive to heavy metals including As, Cd, Hg, Pb.•Multiple heavy metals can be detected on the same SnSe monolayer by analyzing the response peaks.•The SnSe ...monolayer has a fast recovery time for As, Cd, and Hg at room temperature, while for Pb at 498 K.•SnSe monolayers display large bias voltage windows exceeding LOD when detecting As or Pb, indicating great reliability.
Heavy metal pollution has a negative impact on both human health and the environment. The monitoring of heavy metal is therefore very important from a practical standpoint. In this study, the adsorption energy, charge transfer, band, densities of states, and sensitivity of SnSe monolayers toward heavy metals (As, Cd, Cr, Hg, Ni, Pb) were investigated using density functional theory combined with the non-equilibrium Green's function approach. The calculations show that SnSe monolayers have excellent sensitivities exceeding the limit of quantitation (LOQ) towards As, Cd, Hg, and Pb, which are as high as 384467%, 1462%, 1791%, and 26160%, respectively. Moreover, analyzing response peaks at various bias voltages can identify the composition of heavy metals from diverse sources, providing valuable insights for selective heavy metal monitoring. SnSe monolayers exhibit wide bias voltage windows that enhance sensor sensitivity by reaching the detection threshold, while also simplifying sensor encapsulation, resulting in higher reliability. The SnSe monolayer exhibits rapid recovery times for As, Hg, and Cd at room temperature, while for Pb, heating to 498 K is required for rapid recovery. These findings show that SnSe monolayers have a strong potential for constructing extremely sensitive and selective heavy metal sensors that are also reusable, implying that SnSe monolayers might serve as a possible online sensor for environmental monitoring.
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