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Abstract A deep reinforcement learning (DRL) method based on the deep deterministic policy gradient (DDPG) algorithm is proposed to address the problems of a mismatch between the needed training samples and the actual training samples during the training of intelligence, the overestimation and underestimation of the existence of Q‐values, and the insufficient dynamism of the intelligence policy exploration. This method introduces the Actor‐Critic Off‐Policy Correction (AC‐Off‐POC) reinforcement learning framework and an improved double Q‐value learning method, which enables the value function network in the target task to provide a more accurate evaluation of the policy network and converge to the optimal policy more quickly and stably to obtain higher value returns. The method is applied to multiple MuJoCo tasks on the Open AI Gym simulation platform. The experimental results show that it is better than the DDPG algorithm based solely on the different policy correction framework (AC‐Off‐POC) and the conventional DRL algorithm. The value of returns and stability of the double‐Q‐network off‐policy correction algorithm for the deep deterministic policy gradient (DCAOP‐DDPG) proposed by the authors are significantly higher than those of other DRL algorithms.

Based on the celebrated Generalized Nyquist Criterion, this paper presents a new frequency-domain method to analyze the impact of governor-turbine systems (GTSs), power system stabilizers (PSSs) and wind turbine generators (WTGs) on small disturbance stability in power systems. Compared with other common analysis method, the new method can avoid the calculations of eigenvalues, eigenvectors and residues, and the impact of multiple controllers or WTGs can be obtained using simple matrix operations. In addition, the method is intuitive for users since the stability analysis results can be displayed in the complex plane directly. The new method indicates that the impact of controllers and WTGs on power system is determined by the phase of certain elements in the transfer function matrices of controllers, WTGs and synchronous grid. Based on the information provided by the afore-mentioned transfer function matrices, the parameters of controllers can be optimized properly. The proposed method has been tested using the data of a four-machine two-area system and a regional power grid in China. The results demonstrate that the effect of controllers and WTGs can be conveniently identified, and the effectiveness of parameter tuning for controllers is verified.

Coupling the bi-functional mechanism with compressive lattice strain might be an effective way to boost the electrocatalysis of platinum (Pt)-based nanoparticles for methanol oxidation reaction (MOR). This strategy weakens the chemisorption of poisoning CO-like intermediates generated during MOR on the active Pt sites by lowering their d-band center. In this context, we herein report the synthesis of ternary copper-tungsten-platinum (CuWPt) nanoalloys with light doping of W element by simply co-reducing their precursors at elevated temperature. In this ternary alloy system, the presence of only small amount of W element not only weakens the chemisorption of CO-like intermediates by lowering the Pt d-band center through compressive lattice strain, but also cleans the active Pt sites by "hydrogen spillover effect", endowing the as-prepared CuWPt nanoalloys at an appropriate Cu/W/Pt ratio with good activity for MOR. In specific, the ternary CuWPt alloy nanoparticles at a Cu/W/Pt molar ratio of 21/4/75 show a specific activity of 2.5 mA·cm−2 and a mass activity of 2.11 A·mg−1 with a better durability, outperforming those ternary CuWPt alloy nanoparticles at other Cu/W/Pt ratios, binary CuPt alloys and commercial Pt/C catalyst as well as a large number of reported Pt-based electrocatalysts. In addition, a single direct methanol fuel cell (DMFC) assembled using ternary CuWPt nanoalloys as anodic catalysts shows a power density of 24.3 mW·cm−2 and an open-circle voltage of 0.6 V, also much higher than those of the single DMFC assembled from commercial Pt/C catalysts.

Summary: Silver nanomaterials have potent antibacterial properties that are the foundation for their wide commercial use as well as for concerns about their unintended environmental impact. The nanoparticles themselves are relatively biologically inert but they can undergo oxidative dissolution yielding toxic silver ions. A quantitative relationship between silver material structure and dissolution, and thus antimicrobial activity, has yet to be established. Here, this dissolution process and associated biological activity is characterized using uniform nanoparticles with variable dimension, shape, and surface chemistry. From this, a phenomenological model emerges that quantitatively relates material structure to both silver dissolution and microbial toxicity. Shape has the most profound influence on antibacterial activity, and surprisingly, surface coatings the least. These results illustrate how material structure may be optimized for antimicrobial properties and suggest strategies for minimizing silver nanoparticle effects on microbes.

The reduction and dehydration treatment of contaminated sediment from rivers and lakes is a prerequisite for ensuring the subsequent safe disposal. In this study, micro-nano bubbles (MBs) technology was creatively proposed for the conditioning treatment of contaminated sediment to improve its sedimentation and dehydration performance. Orthogonal experiment and single factor experiment were conducted to optimize factors such as bubble size, intake air volume and treatment time. The conditioning effect was analyzed through direct and indirect characterization parameters. The results showed that the range (R) values for bubble size, intake air volume and treatment time were 101.8, 94.5 and 51.6 respectively in the orthogonal analysis. The optimum bubble size, intake air volume and treatment time were 1 μm, 30 L/min and 90 s. At this time, the CST of conditioned sediment decreased to 160.6 s (the reduction rate of 89.29%) and the moisture content of the filter cake decreased to 65.2%. Through the analysis of polysaccharide and MLSS, it was found that the MBs effectively exerted the oxidation and extracellular polymer cracking properties, which released polysaccharides that easily bind to water. The SEM analysis of the filter cake showed a loose structure and rich porosity compared to the undisturbed sediment. Meanwhile, the MBs promoted the homogenization degree of conditioners to achieve efficient dehydration. Therefore, MBs conditioning was verified as a novel and promising technique for improving the dehydration performance of river and lake contaminated sediment.

Hepatitis B virus (HBV) infection is a leading cause of hepatocellular carcinoma (HCC), one of the most prevalent malignant tumors worldwide that poses a significant threat to human health. The multifunctional regulator known as Hepatitis B virus X-protein (HBx) interacts with host factors, modulating gene transcription and signaling pathways and contributing to hepatocellular carcinogenesis. The p90 ribosomal S6 kinase 2 (RSK2) is a member of the 90 kDa ribosomal S6 kinase family involved in various intracellular processes and cancer pathogenesis. At present, the role and mechanism of RSK2 in the development of HBx-induced HCC are not yet clear. In this study, we found that HBx upregulates the expression of RSK2 in HBV-HCC tissues, HepG2, and SMMC-7721 cells. We further observed that reducing the expression of RSK2 inhibited HCC cell proliferation. In HCC cell lines with stable HBx expression, RSK2 knockdown impaired the ability of HBx to promote cell proliferation. The extracellularly regulated protein kinases (ERK) 1/2 signaling pathway, rather than the p38 signaling pathway, mediated HBx-induced upregulation of RSK2 expression. Additionally, RSK2 and cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) were highly expressed and positively correlated in HBV-HCC tissues and associated with tumor size. This study showed that HBx upregulates the expression of RSK2 and CREB by activating the ERK1/2 signaling pathway, promoting the proliferation of HCC cells. Furthermore, we identified RSK2 and CREB as potential prognostic markers for HCC patients.

Endogenous pollutants such as cyanobacteria have an essential impact on the global carbon cycle and climate. Finding a reasonable way to dispose of them has become an urgent task for current watershed management and ecological restoration. According to the engineering practice of cyanobacteria treatment by aerobic fermentation, the carbon emissions of three typical cyanobacterial resource utilization processes, aerobic fermentation without auxiliary materials, aerobic fermentation with auxiliary materials, and incineration for power generation, are compared in this paper, using the mandatory guidelines by the Intergovernmental Panel on Climate Change (IPCC). The results show that the treatment of cyanobacterial mud through aerobic fermentation without auxiliary materials can realize the goal of the harmless recycling of cyanobacterial resources with less carbon emissions, at 175.3 kg CO2·t−1. In addition, each link’s impact on the overall carbon emission process was analyzed. In aerobic fermentation with auxiliary materials, the carbon emissions were significantly contributed by the auxiliary materials, which was accounted for 46.3% of the carbon emission of the whole process and 32.77% of the drying-incineration process. In contrast, with the lowest carbon emission level, aerobic fermentation without auxiliary materials can avoid the production of carbon emissions caused by auxiliary fermentation materials.

Benzoxazole alkaloids exhibit a diverse array of structures and interesting biological activities. Herein we report the identification of a benzoxazole alkaloid-encoding biosynthetic gene cluster (mich BGC) in the marine-derived actinomycete Micromonospora sp. SCSIO 07395 and the heterologous expression of this BGC in Streptomyces albus. This approach led to the discovery of five new benzoxazole alkaloids microechmycin A–E (1–5), and a previously synthesized compound 6. Their structures were elucidated by HRESIMS and 1D and 2D NMR data. Microechmycin A (1) showed moderate antibacterial activity against Micrococcus luteus SCSIO ML01 with the minimal inhibitory concentration (MIC) value of 8 μg mL−1.

Castor (Ricinus communis L.) seed oil is the commercial source of ricinoleate, a valuable raw material used in many industries. Oleoyl-12-hydroxylase (RcFAH12) is a key enzyme in the biosynthesis of ricinoleate, accumulating nearly 90% of the triacylglycerol in castor seeds. Little is known about the transcriptional regulation of RcFAH12. We used rapid amplification of cDNA 5′ ends (5′RACE) to locate the transcription start site (TSS) of RcFAH12, and the sequence of a 2605 bp region, −2506~+99, surrounding the TSS was cloned. We then investigated these regions to promote β-glucuronidase (GUS) expression in transgenic Arabidopsis by the progressive 5′ and 3′ deletions strategies. The GUS staining showed that the GUS accumulation varied in tissues under the control of different deleted fragments of RcFAH12. In addition, the GUS expression driven by the RcFAH12 promoter markedly accumulated in transgenic seeds, which indicated that RcFAH12 might play an important role in the biosynthesis of ricinoleic acid. This study will lay a potential foundation for developing a tissue-specific promoter in oil-seed crops.

Abstract Objective Approximately 300 mg of calcium a day is provided into infants to maintain the physical development of infants, and 5 to 10% bone loss occurs in women during breastfeeding. Hip fractures are considered the most serious type of osteoporotic fracture. We performed this meta-analysis to investigate the association between breastfeeding and osteoporotic hip fractures. Material and methods PubMed and Embase were searched until May 1, 2019, for studies evaluating the relationship between breastfeeding and osteoporotic hip fracture in women. The quality of the included studies was evaluated by the methodological index for non-randomized studies (MINORS). For the dose-response meta-analysis, we used the “generalized least squares for trend estimation” method proposed by Greenland and Longnecker to take into account the correlation with the log RR estimates across the duration of breastfeeding. Results Seven studies were moderate or high quality, enrolling a total of 103,898 subjects. The pooled outcomes suggested that breastfeeding can decrease the incidence of osteoporotic hip fracture (RR = 0.64 (95% CI 0.43, 0.95), P = 0.027). Dose-response analysis demonstrated that the incidence of osteoporotic hip fracture decreased with the increase of breastfeeding time. The RR and 95% CI for 3 months, 6 months, 12 months, and 24 months were RR = 0.93, 95% CI 0.88, 0.98; RR = 0.87, 95% CI 0.79, 0.96; RR = 0.79, 95% CI 0.67, 0.92; and RR = 0.76, 95% CI 0.59, 0.98, respectively, whereas no significant relationship was found between them when the duration of breastfeeding time was more than 25 months. Conclusions Our meta-analysis demonstrated that the incidence of osteoporotic hip fracture decreased with the extension of breastfeeding time. However, there is no significant relationship between them when the duration of breastfeeding time was more than 25 months.

Two new phenylhydrazone derivatives and one new alkaloid, penzonemycins A–B (1–2) and demethylmycemycin A (3), together with three known compounds including an alkaloid (4) and two sesquiterpenoids (5–6), were isolated from the Streptomyces sp. SCSIO 40020 obtained from the Pearl River Estuary sediment. Their structures and absolute configurations were assigned by 1D/2D NMR, mass spectroscopy and X-ray crystallography. Compound 1 was evaluated in four human cancer cell lines by the SRB method and displayed weak cytotoxicity in three cancer cell lines, with IC50 values that ranged from 30.44 to 61.92 µM, which were comparable to those of the positive control cisplatin. Bioinformatic analysis of the putative biosynthetic gene cluster indicated a Japp–Klingemann coupling reaction involved in the hydrazone formation of 1 and 2.

Fast charging-discharging is one of the important requirements for next-generation high-energy Li-ion batteries, nevertheless, electrons transport in the active oxide materials is limited. Thus, carbon coating of active materials is a common method to supply the routes for electron transport, but it is difficult to synthesize the oxide-carbon composite for LiNiO2-based materials which need to be calcined in an oxygen-rich atmosphere. In this work, LiNi0.8Co0.1Mn0.1O2 (NCM811) coated with electronic conductor LaNiO3 (LNO) crystallites is demonstrated for the first time as fast charging-discharging and high energy cathodes for Li-ion batteries. The LaNiO3 succeeds in providing an exceptional fast charging-discharging behavior and initial coulombic efficiency in comparison with pristine NCM811. Consequently, the NCM811@3LNO electrode presents a higher capacity at 0.1 C (approximately 246 mAh g−1) and a significantly improved high rate performance (a discharge specific capacity of 130.62 mAh g−1 at 10 C), twice that of pristine NCM811. Additionally, cycling stability is also improved for the composite material. This work provides a new possibility of active oxide cathodes for high energy/power Li-ion batteries by electronic conductor LaNiO3 coating.

Abstract Ruddlesden–Popper perovskites with a formula of (A′)2(A)n−1BnX3n+1 have recently gained widespread interest as candidates for the next generation of optoelectronic devices. The variations of organic cation, metal halide, and the number of layers in the structure lead to the change of crystal structures and properties for different optoelectronic applications. Herein, the different synthetic methods for 2D perovskite crystals and thin films are summarized and compared. The optoelectronic properties and the charge transfer process in the devices are also delved, in particular, for light‐emitting diodes and solar cells.

Benzofluorene-containing angucyclines, bacterial natural compounds with potential use as therapeutics/antibiotics, occur as dimers. Here, the authors elucidated the dimerization mechanism which turned out to work spontaneously, without enzymatic catalysis.

The fungus strain SCSIO 40433 was isolated from an Arctic-derived glacier sediment sample and characterized as Tolypocladium cylindrosporum. A new compound, cylindromicin (1), and seven known secondary metabolites (2–8) were isolated from this strain. The chemical structures of these compounds were elucidated by comprehensive spectroscopic analyses. Cylindromicin (1) featured a 3,4-dihydro-2H-pyran skeleton. The absolute configuration of compound 1 was assigned via interpretation of key Nuclear Overhauser Effect Spectroscopy (NOESY) correlations and Electronic Circular Dichroism (ECD) calculation. Cylindromicin (1) exhibited significant tyrosinase inhibition activity. This study highlights Polar fungi as a potential resource for new bioactive natural products.

Due to different inertia, sediment particles stop following the trails of water elements during the flow passage of a centrifugal pump. In a dredge pump, deviation characteristics of sediment particles from surrounding fluid are still not crystal clear. Apparently, the deviation makes sediment particles attacking the inner wall and causes wear and tear. In addition, the deviation would also decrease the pump efficiency. In order to understand the motion of the sediment particles and their deviation characteristics inside a dredge pump, authors built a Lagrangian numerical model based on particle’s kinematic balance equations, and then verified it through a rotating platform. The influential factors of the sediment particle motion, such as the rotation speed, as well as the diameter and density of sediment particles, were investigated. Finally, a conclusion is obtained that says if blade profiles are close to the relative trajectory of a particle, this particle will cause minimized wear to the blade wall.

The influence of CO2 partial pressure on the corrosion properties, including corrosion rate, morphology, chemical composition, and corrosion depth, of J55 carbon steel in 30% crude oil/brine at 65 °C was investigated. A corrosion mechanism was then proposed based on the understanding of the formation of localized corrosion. Results showed that localized corrosion occurred in 30% crude oil/brine with CO2. The corrosion rate sharply increased as the CO2 partial pressure (P co 2 ) was increased from 0 to 1.5 MPa, decreased from P co 2 = 1.5 MPa to P co 2 = 5.0 MPa, increased again at P co 2 = 5.0 MPa, and then reached a constant value after P co 2 = 9.0 MPa. The system pH initially decreased, rapidly increased, and then stabilized as CO2 partial pressure was increased. In the initial period, the surface of J55 carbon steel in the CO2/30% crude oil/brine mixtures showed intense corrosion. In conclusion, CO2 partial pressure affects the protection performance of FeCO3 by changing the formation of corrosion scale and further affecting the corrosion rate.

Three new napyradiomycins (1–3) were isolated from the culture broth of a marine-derived actinomycete strain SCSIO 10428, together with six known related analogues napyradiomycin A1 (4), 18-oxonapyradiomycin A1 (5), napyradiomycin B1 (6), napyradiomycin B3 (7), naphthomevalin (8), and napyradiomycin SR (9). The strain SCSIO 10428 was identified as a Streptomyces species by the sequence analysis of its 16S rRNA gene. The structures of new compounds 1–3, designated 4-dehydro-4a-dechlorona pyradiomycin A1 (1), 3-dechloro-3-bromonapyradiomycin A1 (2), and 3-chloro-6, 8-dihydroxy-8-α-lapachone (3), respectively, were elucidated by comparing their 1D and 2D NMR spectroscopic data with known congeners. None of the napyradiomycins 1–9 showed antioxidative activities. Napyradiomycins 1–8 displayed antibacterial activities against three Gram-positive bacteria Staphylococcus and Bacillus strains with MIC values ranging from 0.25 to 32 μg mL−1, with the exception that compound 3 had a MIC value of above 128 μg mL−1 against Staphylococcus aureus ATCC 29213. Napyradiomycins 2, 4, 6, and 7 exhibited moderate cytotoxicities against four human cancer cell lines SF-268, MCF-7, NCI-H460, and HepG-2 with IC50 values below 20 μM, while the IC50 values for other five napyradiomycins 1, 3, 5, 8 and 9 were above 20 μM.