A coherent integration method of an active sonar for maneuvering turning target detection.

The detection probability of underwater weak targets using active sonar is low, and inter-pulse coherent integration can improve the signal-to-noise ratio of echoes. When a target executes a maneuvering turn, complex range and Doppler frequency migrations occur during the coherent integration time that decrease the coherent integration gain. Most existing integration methods simplify the target motion to a finite-order polynomial model but fail to integrate a maneuvering turning target (MTT) due to model mismatch. Hence, this study proposes an underwater MTT integration method based on the modified Radon-Fourier transform. The proposed method constructs a theoretically accurate motion model for the MTT and a phase compensation function to compensate for the Doppler frequency migration. Furthermore, it yields a well-focused integration peak in the range-velocity and offset angle-turn rate dimensions and accurately estimates the target motion parameters. Moreover, the proposed method is suitable for targets with radial and oblique uniform motions. The effectiveness of the proposed method is demonstrated through simulations and a lake test. The proposed method demonstrates good integration performance, with an integration gain approximately 4-7 dB higher than that of traditional methods when using 30 integration pulses.

Underwater Doppler-bearing maneuvering target motion analysis based on joint estimated adaptive unscented Kalman filter.

Noncooperative maneuvering target motion analysis is one of the challenging tasks in the field of underwater target localization and tracking for passive sonar. Underwater noncooperative targets often perform various maneuvers, and the targets are commonly modeled as a combination of constant-velocity models and coordinate-turn models with unknown turning rates. Traditional algorithms for Doppler-bearing target motion analysis are incapable of processing noncooperative maneuvering targets because the algorithms rely on a priori information of the turning rate and the center frequency. To address these shortcomings, this paper proposes the joint estimated adaptive unscented Kalman filter (JE-AUKF) algorithm. The JE-AUKF places the center frequency and turning rate into the state vector and constructs a time-varying state model that self-adapts to a maneuvering target. The JE-AUKF also introduces a time-varying fading factor into the process noise covariance matrix to improve the tracking performance. Simulations and sea trials are conducted to compare the performance of the JE-AUKF with the iterative unscented Kalman filter, the interacting multiple model-unscented Kalman filter, the interacting multiple model-iterative unscented Kalman filter, and the interacting multiple model-joint estimated unscented Kalman filter. The result shows that the JE-AUKF achieves better tracking performance for noncooperative maneuvering targets.

Facilitating New Chromium Reducing Microbes to Enhance Hexavalent Chromium Reduction by In Situ Sonoporation-Mediated Gene Transfer in Soils.

Chromium (Cr) is a heavy metal with a high toxicity and pathogenicity. Microbial reduction is an effective strategy to remove Cr(VI) at contaminated sites but suffers from the low populations and activities of Cr-reducing microorganisms in soils. This study proposed an in situ sonoporation-mediated gene transfer approach, which improved soil Cr(VI) reduction performance by delivering exogenous Cr-transporter chrA genes and Cr-reducing yieF genes into soil microorganisms with the aid of ultrasound. Besides the increasing populations of Cr-resistant bacteria and elevated copy numbers of chrA and yieF genes after sonoporation-mediated gene transfer, three new Cr-reducing strains were isolated, among which Comamonas aquatica was confirmed to obtain Cr-resistant capability. In addition, sonoporation-mediated gene transfer was the main driving force significantly shaping soil microbial communities owing to the predominance of Cr-resistant microbes. This study pioneered and evidenced that in situ soil sonoporation-mediated gene transfer could effectively deliver functional genes into soil indigenous microbes to facilitate microbial functions for enhanced bioremediation, e.g., Cr-reduction in this study, showing its feasibility as a chemically green and sustainable remediation strategy for heavy metal contaminated sites.

The protective effect of thiolutin on doxorubicin-induced H9c2 cardiomyocyte injury.

The use of doxorubicin (DOX) may contribute to cardiotoxicity, limiting its clinical application. Thiolutin (THL) has been found to exert protective roles in various biological activities, while its effects on DOX-induced cardiotoxicity are still uncovered. Cell counting kit 8 assay was utilized to detect cell viability and half maximal inhibitory concentration of THL in H9c2 cardiomyocytes. The level of lactate dehydrogenase (LDH), adenosine triphosphate (ATP), interleukin (IL)-18 and IL-1 beta (IL-1ß) were measured using the corresponding detection kits, and flow cytometry determined cell apoptosis rate. The reactive oxygen species (ROS) accumulation was evaluated by utilizing immunofluorescence or flow cytometry assay. The protein levels of NLR family Pyrin domain 3 (NLRP3), pro-Caspase1, cleaved-Caspase1, gasdermin D (GSDMD) and cleaved-GSDMD (GSDMD-N) in H9c2 cells were detected by immunoblotting assay. The treatment of THL reduced H9c2 cell viability in a gradient-dependent manner. THL treatment reversed the DOX-induced inhibition of proliferation, decrease of ATP, up-regulation of LDH, IL-18, IL-1ß and production of ROS, activation of NLRP3 and inflammasome-mediated pyroptosis in H9c2 cells. Additionally, NLRP3 knockdown abolished the effects of THL in DOX-treated H9c2 cells remarkably. This investigation proved that THL notably ameliorated DOX-induced apoptosis, oxidative stress, and pyroptosis in H9c2 cardiomyocytes. Besides, THL effectively inactivated DOX-induced NLRP3 inflammasome in H9c2 cells. These findings revealed a promising drug to assist DOX in its anti-cancer effects and protect the heart of patients.

Application of magnetic-nanoparticle functionalized whole-cell biosensor array for bioavailability and ecotoxicity estimation at urban contaminated sites.

The bioavailability and ecotoxicity of pollutants are important for urban ecological systems and human health, particularly at contaminated urban sites. Therefore, whole-cell bioreporters are used in many studies to assess the risks of priority chemicals; however, their application is restricted by low throughput for specific compounds and complicated operations for field tests. In this study, an assembly technology for manufacturing Acinetobacter-based biosensor arrays using magnetic nanoparticle functionalization was developed to solve this problem. The bioreporter cells maintained high viability, sensitivity, and specificity in sensing 28 priority chemicals, seven heavy metals, and seven inorganic compounds in a high-throughput manner, and their performance remained acceptable for at least 20 d. We also tested the performance by assessing 22 real environmental soil samples from urban areas in China, and our results showed positive correlations between the biosensor estimation and chemical analysis. Our findings prove the feasibility of the magnetic nanoparticle-functionalized biosensor array to recognize the types and toxicities of multiple contaminants for online environmental monitoring at contaminated sites.

New mechanisms of biochar-assisted vermicomposting by recognizing different active di-(2-ethylhexyl) phthalate (DEHP) degraders across pedosphere, charosphere and intestinal sphere.

Biochar-assisted vermicomposting can significantly accelerate soil DEHP degradation, but little information is known about the underlying mechanisms as different microspheres exist in soil ecosystem. In this study, we identified the active DEHP degraders in biochar-assisted vermicomposting by DNA stable isotope probing (DNA-SIP) and surprisingly found their different compositions in pedosphere, charosphere and intestinal sphere. Thirteen bacterial lineages (Laceyella, Microvirga, Sphingomonas, Ensifer, Skermanella, Lysobacter, Archangium, Intrasporangiaceae, Pseudarthrobacter, Blastococcus, Streptomyces, Nocardioides and Gemmatimonadetes) were responsible for in situ DEHP degradation in pedosphere, whereas their abundance significantly changed in biochar or earthworm treatments. Instead, some other active DEHP degraders were identified in charosphere (Serratia marcescens and Micromonospora) and intestinal sphere (Clostridiaceae, Oceanobacillus, Acidobacteria, Serratia marcescens and Acinetobacter) with high abundance. In biochar-assisted vermicomposting, the majority of active DEHP degraders were found in charosphere, followed by intestinal sphere and pedosphere. Our findings for the first time unraveled the spatial distribution of active DEHP degraders in different microspheres in soil matrices, explained by DEHP dynamic adsorption on biochar and desorption in earthworm gut. Our work highlighted that charosphere and intestinal sphere exhibited more contribution to the accelerated DEHP biodegradation than pedosphere, providing novel insight into the mechanisms of biochar and earthworm in improving contaminant degradation.

Online detection of alkanes by a biological-phase microextraction and biosensing (BPME-BS) device.

Oil spill incidents occur frequently and threaten ecosystems and human health. Solid-phase microextraction allows direct alkane extraction from environmental matrices to improve the limit of detection but is unable to measure alkanes on site. A biological-phase microextraction and biosensing (BPME-BS) device was developed by immobilising an alkane chemotactic Acinetobacter bioreporter ADPWH_alk in agarose gel to achieve online alkane quantification with the aid of a photomultiplier. The BPME-BS device had a high enrichment factor (average 7.07) and a satisfactory limit of detection (0.075 mg/L) for alkanes. The quantification range was 0.1-100 mg/L, comparable to a gas chromatography flame ionisation detector and better than a bioreporter without immobilisation. ADPWH_alk cells in the BPME-BS device maintained good sensitivity under a wide range of environmental conditions, including pH (4.0-9.0), temperature (20-40 °C), and salinity (0.0-3.0%), and its response remained stable within 30 days at 4 °C. In a 7-day continual measurement, the BPME-BS device successfully visualised the dynamic concentration of alkanes, and a 7-day field test successfully captured an oil spill event, helping in source apportionment and on-scene law enforcement. Our work proved that the BPME-BS device is a powerful tool for online alkane measurement, showing substantial potential for fast detection and rapid response to oil spills on site and in situ.

Different phenanthrene degraders between free-cell mediated and biochar-immobilization assisted soil bioaugmentation as identified by RNA-based stable isotope probing (RNA-SIP).

Bioaugmentation (BA) is an effective approach to remove polycyclic aromatic hydrocarbons (PAHs) from contaminated soils, and biochar is frequently used to enhance PAH degradation performance. In this study, phenanthrene (PHE) degradation behavior and active degraders in a petroleum-contaminated soil were investigated and compared between free-cell mediated and biochar-immobilization assisted bioaugmentation. Biochar-immobilization assisted bioaugmentation (BA-IPB) introduced PHE degraders immobilized on biochar and effectively promoted PHE degradation, achieving higher PHE removal efficiencies within 24 h (~58 %) than free-cell mediated bioaugmentation (BA-FPB, ~39 %). Soil microbial community structure significantly changed in both BA-FPB and BA-IPB treatments. Through RNA-stable isotope probing (SIP), 14 and 11 bacterial lineages responsible for in situ PHE degradation were identified in BA-FPB and BA-IPB treatments, respectively. ASV_17 in BA-FPB treatment was Rhodococcus in the exogenous bacterial mixture; in contrast, none of exogenous bacteria were involved in PHE degradation in BA-IPB treatment. Methylobacterium (ASV_186), Xanthomonas (ASV_41), Kroppenstedtia (ASV_205), Scopulibacillus (ASV_243), Bautia (ASV_356), and Lactobacillus (ASV_376) were identified as PHE degraders for the first time. Our findings expanded the knowledge of the active PHE degraders and underlying mechanisms in bioaugmentation process, and suggested biochar-immobilization assisted bioaugmentation as a promising strategy for the bioremediation of PAH contaminated soils.

Altered active pyrene degraders in biosurfactant-assisted bioaugmentation as revealed by RNA stable isotope probing.

Bioaugmentation is an effective approach for removing pyrene from contaminated sites, and its performance is enhanced by a biosurfactant. To reveal the mechanisms of biosurfactant-assisted bioaugmentation, we introduced RNA stable isotope probing (RNA-SIP) in the pyrene-contaminated soils and explored the impacts of rhamnolipid on the pyrene degradation process. After 12-day degradation, residual pyrene was the lowest in the bioaugmentation treatment (7.76 ± 1.57%), followed by biosurfactant-assisted bioaugmentation (9.86 ± 2.58%) and enhanced natural attenuation (23.97 ± 1.05%). Thirteen well-known and two novel pyrene-degrading bacteria were confirmed to participate in the pyrene degradation. Pyrene degradation was accelerated in the biosurfactant-assisted bioaugmentation, manifested by the high diversity of active pyrene degraders. Our findings expand the knowledge on pyrene degrading bacteria and the mechanisms of pyrene degradation in a bioaugmentation process.

Robust high-resolution direction-of-arrival estimation method using DenseBlock-based U-net.

Direction-of-arrival (DOA) estimation is widely used in underwater detection and localization. To address the high-resolution DOA estimation problem, a DenseBlock-based U-net structure is proposed in this paper. U-net is a U-shaped fully convolutional neural network, which yields a two-dimensional image. DenseBlock is a more efficient structure than typical convolutional layers. The proposed network replaces the concatenated convolutional layers in the original U-net with DenseBlocks. Through training, the network can remove the interference of sidelobes and noise in a conventional beam forming bearing-time record (BTR) and get a clean BTR; hence, this method has narrow beam width and few sidelobes. In addition, the network can be trained by simulation data and applied in actual data when the simulated and actual data are similar in BTR features, so the method has high generalization. For a multi-target problem, the network does not need to be trained on all cases with different target quantities and therefore can reduce the training set size. As a data-driven method, it does not rely on prior assumptions of the array model and possesses better robustness to array imperfections than typical model-based DOA algorithms. Simulations and experiments verify the advantages of the proposed method.

Identification of pyrene degraders via DNA-SIP in oilfield soil during natural attenuation, bioaugmentation and biostimulation.

Pyrene is a model contaminant of high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs), which are compounds that have potential carcinogenic effects and pose a serious threat to human health. Finding effective pyrene-degrading bacteria is crucial for removing PAHs from soil. In this study, DNA-based stable isotope probing (DNA-SIP) technology was used to investigate pyrene degraders in PAH-contaminated oilfield soil during natural attenuation (NA), bioaugmentation (BA) and biostimulation (BS). The results show that BA played an important role in pyrene degradation with the highest pyrene removal rate (~95%) after 12 days incubation, followed by removal rates of ~90% for NA and ~30% for BS. In addition, 6 novel pyrene degraders were identified, while 12 well-known PAH degraders were demonstrated to participate in the biodegradation of pyrene. Additionally, the external homologous strains introduced during BA promoted the degradation of pyrene, but not by directly participating in the metabolism of the target compound. Rhamnolipid supplementation during BS promoted the involvement of more microorganisms in the degradation of pyrene, which was beneficial to identifying more pyrene degraders via DNA-SIP. These findings provide new insight into the effects of external homologous strains and supplementary rhamnolipids on pyrene degradation.