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The notion of stability margin (SM) plays an important role in control engineering. For multiple‐input multiple‐output (MIMO) systems, the classic SM is no longer applicable. The one‐loop‐at‐a‐time analysis method may lead to unreliable SMs. Although some robust SM analysis methods are popular in MIMO systems, they are model‐based or not easy‐to‐use in engineering sometimes. In this paper, ℒ2$$ {\mathcal{L}}_2 $$ gain margin and ℒ2$$ {\mathcal{L}}_2 $$ time‐delay margin are defined for linear MIMO systems, and a corresponding SM analysis method is proposed by utilizing a loop transformation and the small‐gain theorem. Most importantly, a data‐driven method for measuring the defined SMs is also presented. As a frequency‐domain method, this method can be used to experimentally obtain the SMs of MIMO systems on model‐free occasions. The proposed SM analysis method and measurement method are simple and practical. Two simulation studies and an experimental test are performed to illustrate the effectiveness and practicability of the proposed method. [ABSTRACT FROM AUTHOR]

Intersex is defined as sexually aberrant individuals composed of a single sexual genotype that simultaneously displays female and male characteristics. The occurrence of intersex individuals in egg parasitoids, Trichogramma spp., is often associated with the symbiotic bacteria, Wolbachia, which induce thelytokous parthenogenesis of Trichogramma. It is still unclear whether intersex was caused by the reduced Wolbachia titer, effects of abiotic factors, or interactions between abiotic factors and Wolbachia. To answer this question, the females of Wolbachia-infected (TDW) and uninfected (TD) Trichogramma dendrolimi were treated using different tetracycline or rifampicin concentrations. The results showed that the proportion of intersexes or males of TDW offspring significantly increased as the concentration of both antibiotics increased; however, they did not occur without antibiotics. Occurrence of intersex was not observed in TD offspring. Twelve types of intersex were found and categorized by masculinization levels. The masculinized level of offspring intersex increased with tetracycline but not with rifampicin. Wolbachia titers of maternal TDW females significantly decreased with higher antibiotics concentrations. Wolbachia titers of intersex offspring were higher than offspring males, lower than offspring females, and negatively correlated with masculinized level of offspring intersex. The results revealed that the frequency and masculinized level of offspring intersex is quantitatively dependent on Wolbachia titer. Our findings provide an insight into the interaction of Wolbachia titers on the sex determination of Trichogramma. [ABSTRACT FROM AUTHOR]

Synephrine hydrochloride, an alkaloid compound extracted from immature bitter orange, has many pharmacological effects such as anticancer effect, antioxidant effect and antidepression effect. In this paper, the pharmacological effects and mechanism of synephrine hydrochloride were reviewed in order to provide a theoretical basis for the development and application of synephrine hydrochloride. [ABSTRACT FROM AUTHOR]

The traditional multicopter design method usually requires a long iterative process to find the optimal design based on given performance requirements. The method is uneconomical and inefficient. In this article, a practical method is proposed to automatically calculate the optimal multicopter design according to the given design requirements including flight time, altitude, payload capacity, and maneuverability. The proposed method contains two algorithms, including an off-line algorithm and an online algorithm. The off-line algorithm finds the optimal components (propeller and electronic speed controller) for each motor to establish its component combination, and subsequently, these component combinations and their key performance parameters are stored in a combination database. The online algorithm obtains the multicopter design results that satisfy the given requirements by searching through the component combinations in the database and calculating the optimal parameters for the battery and airframe. Subsequently, these requirement-satisfied multicopter design results are obtained and sorted according to an objective function that contains evaluation indexes, including size, weight, performance, and practicability. The proposed method has the advantages of high precision and quick calculating speed because parameter calibrations and time-consuming calculations are completed offline. Experiments are performed to validate the effectiveness and practicality of the proposed method. Comparisons with the brutal search method and other design methods demonstrate the efficiency of the proposed method. Note to Practitioners—The proposed method is fast and practical to obtain an optimal solution by only using a low-performance web server, and the algorithm has been published online at http://www.flyeval.com/recalc.html to provide an online optimization design service for users. To make it convenient to apply the proposed method to multicopter designs, the propulsion system combination database obtained by our off-line algorithm is released along with the article. This database includes more than 1500 experimentally calibrated propulsion combinations, which are adequate for readers to use the proposed optimization algorithms to design multicopters with weights (sizes) ranging from 0.2 to 50 kg. [ABSTRACT FROM AUTHOR]

Daurisoline is an important bisbenzylisoquinoline alkaloid and manly exists in the rhizome of Menispermum dauricum DC., a plant of the family Menispermaceae. Due to its pharmacological effects such a anti-arrhythmia, anti-ischemia and anti-cancer, daurisoline has attracted wide attention of researchers. In this paper, the pharmacological effects and action mechanism of daurisoline were reviewed in combination with relevant research literature, to provide a theoretical basis for the development and clinical application of daurisoline. [ABSTRACT FROM AUTHOR]

This paper presents a model for predicting the water temperature of the reservoir incorporating with solar radiation to analyze and evaluate the water temperature of large high-altitude reservoirs in western China. Through mutual information inspection, the model shows that the dependent variable has a good correlation with water temperature, and it is added to the sample feature training model. Then, the measured water temperature data in the reservoir for many years are used to establish the support vector regression (SVR) model, and genetic algorithm (GA) is introduced to optimize the parameters, so as to construct an improved support vector machine (M-GASVR). At the same time, root-mean-square error, mean absolute error, mean absolute percentage error, and Nash–Sutcliffe efficiency coefficient are used as the criteria for evaluating the performance of SVR model, ANN model, GA-SVR model, and M-GASVR model. In addition, the M-GASVR model is used to simulate the water temperature of the reservoir under different working conditions. The results show that ANN model is the worst among the four models, while GA-SVR model is better than SVR model in terms of metric, and M-GASVR model is the best. For non-stationary sequences, the prediction model M-GASVR can well predict the vertical water temperature and water temperature structure in the reservoir area. This study provides useful insights into the prediction of vertical water temperature at different depths of reservoirs. [ABSTRACT FROM AUTHOR]

Sensitive and rapid detection of pathogenic bacteria plays an important role in avoiding food poisoning. However, the practical application value of conventional assays for detection of foodborne bacteria, are limited by major drawbacks; these include the laboriousness of pure culture preparation, complexity of DNA extraction for polymerase chain reaction, and low sensitivity of enzyme-linked immunosorbent assay. Herein, we designed a non-complex strategy for the sensitive, quantitative, and rapid detection of Salmonella typhimurium with high specificity, using an anti-Salmonella typhimurium IgG-AuNC-based immunofluorescent-aggregation assay. Salmonella typhimurium was agglutinated with fluorescent anti-Salmonella typhimurium IgG-AuNC on a glass slide, and observed using a fluorescence microscope with photoexcitation and photoemission at 560 nm and 620 nm, respectively. Under optimized reaction conditions, the AuNC-based immunofluorescent-aggregation assay had a determination range between 7.0 × 103 and 3.0 × 108 CFU/mL, a limit of detection of 1.0 × 103 CFU/mL and an assay response time of 3 min. The technique delivered good results in assessing real samples. [ABSTRACT FROM AUTHOR]

The success of deep learning methodologies hinges upon the availability of meticulously labeled extensive datasets. However, when dealing with medical images, the annotation process for such abundant training data often necessitates the involvement of experienced radiologists, thereby consuming their limited time resources. In order to alleviate this burden, few-shot learning approaches have been developed, which manage to achieve competitive performance levels with only several labeled images. Nevertheless, a crucial yet previously overlooked problem in few-shot learning is about the selection of template images for annotation before learning, which affects the final performance. In this study, we propose a novel TEmplate Choosing Policy (TECP) that aims to identify and select "the most worthy" images for annotation, particularly within the context of multiple few-shot medical tasks, including landmark detection, anatomy detection, and anatomy segmentation. TECP is composed of four integral components: (1) Self-supervised training, which entails training a pre-existing deep model to extract salient features from radiological images; (2) Alternative proposals for localizing informative regions within the images; and (3) Representative Score Estimation, which involves the evaluation and identification of the most representative samples or templates. (4) Ranking, which rank all candidates and select one with highest representative score. The efficacy of the TECP approach is demonstrated through a series of comprehensive experiments conducted on multiple public datasets. Across all three medical tasks, the utilization of TECP yields noticeable improvements in model performance. [ABSTRACT FROM AUTHOR]

• A multiple-drought cascading framework based on causal inference was proposed. • Multiple-drought cascading risks were quantified by considering multiple time lags and complex factors. • The cascading risk of SD and GD peaks at a 3-7 month lag, during which time GD is most significantly influenced by vegetation. Comprehensively evaluating evolution of drought has an important guiding significance to drought early warning systems and disaster control. Drought is a major natural disaster. Although there are multiple methods including statistics to study drought propagation at present, the evolution of droughts is a complex phenomenon, existing physical and data-driven methods demonstrate unsatisfactory estimation performance. To address this issue, a new type of multiple-drought cascading framework was proposed. The peculiarity of this framework is that based on the principle of causal inference, a generalized linear regression model was established to quantify cascading effect of multiple droughts in disaster chain systems and explore influences of complicated factors outside the system on the cascading effect. The proposed framework was evaluated based on meteorological, soil and groundwater drought conditions of the Yanhe River basin, China. The results prove that study from the perspective of cascading disasters can intuitively characterize disasters of different types of drought signal propagation in the disaster chain system. The results also revealed a top-to-down drought long-chain cascading relationship in moisture transfer in the atmosphere, pedosphere, and lithosphere and discovered that climate change and vegetation restoration are the primary influencing factors of different links. In the framework, a novel model was constructed to quantify multiple-drought cascading effect considering influences of complex factors to facilitate the enhancement of policy planning and can help reduce negative influences of multiple cascading disasters. This framework is also expected to be applied in other areas to enrich the understanding of mechanisms underlying multiple-drought cascading disasters. [ABSTRACT FROM AUTHOR]

There is no recognized serum biomarker to predict the recurrence of endometrial carcinoma (EC). We aimed to explore serum human epididymis protein 4 (HE4) and cancer antigen 125 (CA125) as the biomarkers to predict and monitor recurrence of type II EC. 191 patients diagnosed with type II EC were involved for this retrospective study. Comparing recurrent with non-recurrent patients, HE4 levels resulted a statistically significant difference at primary diagnosis and recurrence, respectively (P = 0.002 and P = < 0.001), while CA125 levels resulted statistically significant (P = < 0.001) at recurrence. According to receiver operating characteristic curve analysis, the areas under the curve were significant for HE4 levels at primary diagnosis and recurrence predicting recurrence. Furthermore, CA125 levels at recurrence were significant. And the combination of both markers showed the higher sensitivity and specificity than single one. Patients with higher HE4 levels were associated with worse disease-free survival and overall survival, the opposite was true for patients with lower HE4 levels. The preoperative HE4 levels could be used to evaluate the risk factors of type II EC. Which suggested that HE4 levels might associated with the prognosis of type II EC. And combination of HE4 and CA125 could be applied to monitor recurrence during follow-up. [ABSTRACT FROM AUTHOR]

Background: To date, there are no consensus methods to evaluate the high-risk factors and prognosis for managing the personalized treatment schedule of patients with endometrial carcinoma (EC) before treatment. Apparent diffusion coefficient (ADC) is regarded as a kind of technique to assess heterogeneity of malignant tumor. Purpose: To explore the role of ADC value in assessing the high-risk factors and prognosis of EC. Material and Methods: A retrospective analysis was made on 185 patients with EC who underwent 1.5-T magnetic resonance imaging (MRI). Mean ADC (mADC), minimum ADC (minADC), and maximum ADC (maxADC) were measured and compared in different groups. Results: Among the 185 patients with EC, the mADC and maxADC values in those with high-risk factors (type 2, deep myometrial invasion, and lymph node metastasis) were significantly lower than in those without. According to receiver operating characteristic (ROC) curve analysis, the areas under the curve (AUC) were significant for mADC, minADC, and maxADC predicting high-risk factors. Furthermore, the AUCs were significant for mADC and maxADC predicting lymph node metastasis but were not significant for minADC. Patients with lower mADC were associated with worse overall survival and disease-free survival; the opposite was true for patients with higher mADC. Conclusion: Our study showed that ADC values could be applied to assess the high-risk factors of EC before treatment and might significantly relate to the prognosis of EC. It might contribute to managing initial individualized treatment schedule and improve outcome in patients with EC. [ABSTRACT FROM AUTHOR]

There exist at least two viewpoints on the internal model principle (IMP), namely the cancelation viewpoint and the geometrical viewpoint. However, neither of them is applicable to repetitive control (RC, or repetitive controller, also designated RC) of nonlinear systems directly. Because of this, error dynamics are often derived to transform a periodic signal tracking problem into a rejection problem. This not only fails to represent the special feature of periodic signals but also restricts the applications of RC. In view of this, this paper proposes a new viewpoint on IMP, namely the actuator-focussed viewpoint. With this, the periodic signal tracking problem can be converted into a stability problem without deriving error dynamics for linear periodic systems and nonlinear systems. In order to demonstrate its effectiveness, the proposed design approach is applied to RC problems for a linear periodic system, a minimum-phase nonlinear system and a nonminimum-phase nonlinear system. [ABSTRACT FROM AUTHOR]

Ecosystem stability is essential to its sustainable functions and services to humanity. Although climate warming is projected to vary from 1 to 5°C by the end of 21st century, how the temporal stability of plant community biomass production responds to different warming scenarios remains unclear.To fill this knowledge gap, we conducted a 6‐year field experiment with three levels of warming treatments (control, +1.5°C, +2.5°C) by using infrared radiators, in an alpine meadow on the Qinghai–Tibet Plateau.We found that low‐level warming (+1.5°C), compared to the control, did not significantly change the temporal stability of plant community biomass production and its underlying causes, including species diversity, compensatory dynamics, mean–variance scaling, biomass temporal stability of plant population (the average of temporal stability of species biomass production of all species in the community) or dominant species. However, high‐level warming (+2.5°C) significantly reduced them. Species diversity was not a significant predictor of temporal stability of plant community biomass production in this species‐rich ecosystem, regardless of the magnitude of warming, while co‐existing species compensatory dynamics and the biomass temporal stability of dominant species determined the response of temporal stability of plant community biomass production to warming.Synthesis. Our results suggest that the responses of plant community biomass temporal stability and its underlying mechanisms to climate warming depend on warming magnitudes. The findings highlight the various responses of ecosystem functions and services to different warming scenarios and imply that ecosystem will fail to maintain and provide stable biomass‐related services for humanity under high‐level climate warming. [ABSTRACT FROM AUTHOR]

Objective: Ascites is a tumor microenvironment, ascites and massive ascites‐induce compression could promote the progression of epithelial ovarian cancer (EOC); however, the impact of ascites volume on clinical outcomes has not been studied extensively. We aimed to investigate the association between ascites volume and clinical outcomes especially platinum resistance in EOC. Methods: We retrospectively evaluated a total of 546 EOC patients with respect to the amount of ascites, clinicopathologic factors, and survival. Using the threshold of 1500 ml to classify patients into small‐ and large‐volume ascites groups, we analyzed the correlation between ascites volume and clinicopathological factors, including platinum‐free interval (PFI), and prognosis. Results: Patients with large volume ascites were more likely to present with later stage disease, primary platinum‐resistant (PPR) cancer, and suboptimal cytoreduction. Prolonged PFI was associated with decreased ascites volume. The large‐volume ascites group showed worse progression‐free survival (PFS) and overall survival (OS). An increase in ascites volume was associated with an increased risk of disease recurrence (hazard ratio [HR] = 1.115, 95% confidence interval [CI]: 1.035–1.200) and death (HR = 1.213, 95% CI: 1.090–1.350). Conclusions: Ascites was an independent predictor of PFS and OS in EOC patients. A large volume of ascites predicated a shortened PFI, an increased incidence of PPR and suboptimal cytoreduction. Thus, the volume of ascites is a simply available clinical parameter, which could be used to evaluate the prognosis and platinum resistance of EOC patients early, it contributes to formulate individualized treatment plan and improve the outcome of EOC patients. [ABSTRACT FROM AUTHOR]

Objectives. Whether patent foramen ovale (PFO) closure is effective on migraine is controversial. This article was aimed at assessing the efficacy of PFO closure on migraine based on randomized controlled trials (RCTs) and observational studies. Methods. We searched PubMed, Embase, and Cochrane databases up to October 2020 evaluating PFO closure versus control in patients with migraine, then conducted a meta-analysis of all RCTs and observational studies, respectively. The main outcomes were (1) respond rate: complete cessation of migraine; (2) reduction in the frequency of migraine attacks per month; and (3) reduction in migraine days per month. Results. Seven studies (3 RCTs and 4 observational studies), containing 887 migraine patients, were identified. (1) The respond rate of PFO closure on migraine was significantly higher than control group both in RCT subgroup and observational studies subgroup (OR 3.86, 95% CI 1.35-11.04, P = 0.01 in RCTs; OR 8.28, 95% CI 2.31-29.67, P = 0.001 in observational studies). (2) Reduction in frequency of migraine attacks was higher in PFO closure group compared with control group in the RCT subgroup analysis (mean difference MD = 0.57 , 95% CI 0.23-0.90, P = 0.0009). (3) Reduction in migraine days was also higher in PFO closure group compared with control group in the RCT subgroup analysis (MD = 1.33 , 95% CI 0.35-2.31, P = 0.008). Conclusions. PFO closure might be suitable for migraine patients, especially for migraine with aura, by cessation of migraine headaches or reducing migraine attacks and migraine days. [ABSTRACT FROM AUTHOR]

Object detection is an important topic for visual data processing in the visual computing area. Although a number of approaches have been studied, it still remains a challenge. There is a suitable way to promote image classifiers by blending training with blended images and corresponding blended labels. However, our experiments show that directly moving existing blending methods from classification to object detection will cause the training process become harder and eventually will lead to a bad performance. Inspired by our discovery, this paper presents a multi-phase blending method with incremental blending intensity to improve the accuracy of object detectors and achieve remarkable improvements. Firstly, to adapt blending method to detection task, we propose a smoothly scheduled and incremental blending intensity to control the degree of multi-phase blending. Based on the above dynamic coefficient, we propose an incremental blending method, in which the blending intensity is smoothly increased from zero to full. Therefore, more complex and various data can be created to achieve the goal of regularizing the network. Secondly, we also design an incremental hybrid loss function to replace the original loss function. The blending intensity in our loss function increases smoothly, which is controlled by our scheduled coefficient. Thirdly, we further discard more negative examples in our multi-phase training process than other typical training methods and processes. By doing so, we can regularize the neural network to enhance generalization capability with data diversity and eventually to improve the accuracy in object detection. Another advantage is that there is no negative effect on evaluation because our method is just applied during the training process. Typical experiments show the proposed method improves the generalization of the detection networks. On PASCAL VOC and MS COCO, our method outperforms the state-of-the-art RFBNet of one-stage detectors for real-time processing. [ABSTRACT FROM AUTHOR]

Background and aims: Responses of grassland carbon (C) cycling to changes in precipitation and land use remain a major uncertainty in model prediction of future climate. It remains even far from clear on how does clipping regulate the response sensitivity of grassland C sequestration to precipitation change. Methods: We conducted a manipulative field experiment with five precipitation treatments (1/12P, 1/4P, 1/2P, 3/4P, P, and 5/4P, where P is the growing season precipitation) interacting with clipping treatments in an alpine meadow to examine net ecosystem C uptake and its associated processes in response to clipping and precipitation gradients as well as their interaction. Results: (1) clipping significantly increased soil temperature in 2016 and 2017, while had no effect on soil moisture; (2) clipping also stimulated the net ecosystem productivity (NEP) and gross ecosystem productivity (GEP) during the two growing seasons; (3) although there were no significantly interactive effects of clipping with precipitation changes, clipping increased the response sensitivity of C uptakes to soil moisture changes. NEP increased more with soil moisture under clipping (0.21 μmol m−2 s−1 v/v−1) than unclipping treatments (0.11 μmol m−2 s−1 v/v−1). This was due to the compensatory growth and the positive effect of clipping on soil temperature, which stimulated plant growth and productivity. Conclusions: Our findings suggest that clipping will aggravate grassland's sensitivity to precipitation change. These findings highlight the important role of land use change in regulating ecosystem C sequestration under further climate conditions in an alpine meadow. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen carriers (LOHCs) are powerful systems for the efficient unloading and loading molecular hydrogen. Herein, a liquid‐to‐liquid organic hydrogen carrier system based on reversible dehydrogenative coupling of ethylene glycol (EG) with ethanol catalysed by ruthenium pincer complexes is reported. Noticeable advantages of the current LOHC system is that both reactants (hydrogen‐rich components) and the produced esters (hydrogen‐lean components) are liquids at room temperature, and the dehydrogenation process can be performed under solvent and base‐free conditions. Moreover, the hydrogenation reaction proceeds under low hydrogen pressure (5 bar), and the LOHC system has a relatively high theoretical gravimetric hydrogen storage capacity (HSC>5.0 wt %), presenting an attractive hydrogen storage system. [ABSTRACT FROM AUTHOR]

Single-crystal-to-single-crystal (SCSC) transformation has been demonstrated to provide an ideal platform to explore the formation process of chemical bonds, which is conducive to making function-oriented crystal synthesis a reality. A solvent as a ligand or a structure-directing agent plays a significant role in the structural formation of coordination polymers (CPs), and its removal/adsorption or exchange can affect the change in metal coordination environments. In this article, we provide a brief overview of recent progress in the effect of coordinated solvent molecules on metal coordination environments of CPs in SCSC transformations. We highlight three different categories based on their stimuli conditions, heat treatment, immersion in solvent or mother liquid, and exposure to vapor. We try to discuss the criteria for CPs in which the metal coordination spheres can be affected by the coordinated solvents, which may provide new insights into the rational design and construction of CPs with the desired structures and properties. [ABSTRACT FROM AUTHOR]

We investigate quantum teleportation in the two-copy setting based on GHZ measurement and propose the detailed protocol. The output state after the teleportation is analyzed, and the protocol is proved to be trace preserving. The general expression of the optimal teleportation fidelity is derived. The optimal teleportation fidelity is shown to be a linear function of two-copy fully entangled fraction, which is invariant under local unitary transformations. At last, we show two-copy teleportation based on GHZ measurement can be better than one-copy teleportation by an explicit example, which is amenable to demonstration in experiments. Our study is significant for improving the fidelity of teleportation for some limited resource which cannot be significantly distilled. Moreover, it can inspire us to find many other more efficient protocols for teleportation. [ABSTRACT FROM AUTHOR]

The robust sampled-data repetitive control (RC, or repetitive controller, also designated RC) problem for non-minimum phase nonlinear systems is both challenging and practical. This paper proposes a sampled-data output-feedback RC design for a class of non-minimum phase systems with measurable nonlinearities to improve the robustness against the period variation. The design relies on additive-state decomposition, by which the output-feedback RC problem is decomposed into an output-feedback RC problem for a linear time-invariant component and a state-feedback stabilisation problem for a nonlinear component. Thanks to the decomposition, existing controller design methods in both the frequency domain and the time domain are employed to make the robustness and discretisation for a continuous-time nonlinear system tractable. In order to demonstrate the effectiveness, an illustrative example is given. [ABSTRACT FROM AUTHOR]

The effects of drought, a devastating natural disaster, have expanded due to intense global warming. Therefore, studying the spatio-temporal evolution and formation mechanism of drought is urgent and important. In this paper, the standardized precipitation evapotranspiration index (SPEI) of the source region of Yellow River was calculated for the years 1961–2015, and the heuristic segmentation and Modified Mann-Kendall methods were used to study the change points and trends of precipitation, temperature, and SPEI. The empirical orthogonal function was used to study the major modes of the SPEI, and cross wavelet analysis was used to demonstrate the relationship between SPEI and large-scale climate factors. The results initially demonstrated no change point and an insignificant positive trend in precipitation. Temperature revealed a significant increasing trend, and a change point was detected in 1997. SPEI indicated a change point in 1993, and a significant increasing trend was observed thereafter. These findings reveal that drought in the study area is highly related to the El Niño-Southern Oscillation. The North Atlantic and Arctic oscillations caused similar impacts on drought. By comparison, changes in SPEI were slightly related to the Pacific decadal oscillation. These results provide useful information for evaluating drought changes in the study area, early warning of drought, and water resource management. [ABSTRACT FROM AUTHOR]

Global climate change models predict an increase in the frequency and intensity of extreme droughts, with uncertain ecological impacts across ecosystems. In particular, it is not clear when extreme droughts will elicit extreme ecological responses.For this study, we employed three complementary approaches to explore the relationships between extreme drought and ecosystem responses. First, we used global data mining to evaluate the relationship between extreme gross primary productivity and extreme precipitation from 1980 to 2013. Second, we conducted a meta‐analysis using 132 drought experiments across the globe to assess the response ratios (RRs) of above‐ground net primary productivity (ANPP) to extreme versus non‐extreme drought treatments. Third, we examined community and ecosystem responses in an alpine meadow to a drought gradient experiment, which included five precipitation treatment levels (1/12 P, 1/4 P, 1/2 P, 3/4 P, and P, where P is the growing season precipitation).This study had three key results. In our historical data mining, we found that extreme droughts elicited extreme ecological responses only 15.1% of the time. The meta‐analysis results indicated that there were no significant differences in the RRs of ANPP between the extreme versus non‐extreme drought treatments. The drought gradient experiment results revealed that although the four drought treatments were statistically extreme, only the most extreme drought treatment (1/12 P) significantly reduced ANPP over the 3 years. Meanwhile, species richness and asynchrony were significantly reduced under the 1/12 P treatment, which led to a significant reduction in productivity.Synthesis. These results suggest that extreme ecological responses to extreme drought may be less frequent than previously thought. But when they do occur, extreme ecological responses may be driven by plant community changes such as species asynchrony, species loss or species reordering. Our experimental results highlight the key role of community dynamics in determining the resistance of ecosystem productivity to extreme drought, which should be assessed when predicting ecological responses to climate change. [ABSTRACT FROM AUTHOR]

Visible-light-driven organic photochemical reactions have attracted substantial attention from the synthetic community. Typically, catalytic quantities of photosensitizers, such as transition metal complexes, organic dyes, or inorganic semiconductors, are necessary to absorb visible light and trigger subsequent organic transformations. Recently, in contrast to these photocatalytic processes, a variety of photocatalyst-free organic photochemical transformations have been exploited for the efficient formation of carbon–carbon and carbon–heteroatom bonds. In addition to not requiring additional photocatalysts, they employ low-energy visible light irradiation, have mild reaction conditions, and enable broad substrate diversity and functional group tolerance. This review will focus on a summary of representative work in this field in terms of different photoexcitation modes. 1 Introduction 2 Visible Light Photoexcitation of a Single Substrate 3 Visible Light Photoexcitation of Reaction Intermediates 4 Visible Light Photoexcitation of EDA Complexes between Substrates 5 Visible Light Photoexcitation of EDA Complexes between Substrates and Reaction Intermediates 6 Visible Light Photoexcitation of Products 7 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

This paper presents a novel method for efficiently solving a trajectory planning problem for swarm robotics in cluttered environments. Recent research has demonstrated high success rates in real-time local trajectory planning for swarm robotics in cluttered environments, but optimizing trajectories for each robot is still computationally expensive, with a computational complexity from O (k (n t , ε) n t 2) to O (k (n t , ε) n t 3) where n t is the number of parameters in the parameterized trajectory, ε is precision, and k (n t , ε) is the number of iterations with respect to n t and ε. Furthermore, the swarm is difficult to move as a group. To address this issue, we define and then construct the optimal virtual tube, which includes infinite optimal trajectories. Under certain conditions, any optimal trajectory in the optimal virtual tube can be expressed as a convex combination of a finite number of optimal trajectories, with a computational complexity of O (n t) . Afterward, a hierarchical approach including a planning method of the optimal virtual tube with minimizing energy and distributed model predictive control is proposed. In simulations and experiments, the proposed approach is validated and its effectiveness over other methods is demonstrated through comparison. [ABSTRACT FROM AUTHOR]

Abstract Alginate/gelatin blended hydrogel fibers were successfully prepared based on sodium alginate cross-linked by Ca2+ and gelatin cross-linked by oxidized starch through the wet spinning process. The structure, surface morphologies, swelling properties of alginate hydrogel fibers and alginate/gelatin blended hydrogel fibers were examined by Fourier transform infrared analysis (FTIR), cross-linking degree test, element analysis test and scanning electron microscopy (SEM). While mechanical properties test, water absorption and retention properties test provide the mechanical, water absorption and retention properties. FTIR, cross-linking degree and element analysis results indicate that there is gelatin remaining in alginate/gelatin blended hydrogel fibers. However, the cross-linking of gelatin by oxidized starch is not completed with some dissociative gelatin solvated in the coagulation bath. Among the mentioned fibers, F S10G2 is the best to improve the properties of alginate/gelatin blended hydrogel fibers with an optimal mass ratio of sodium and gelatin. The excessive additive amount of gelatin leads to the aggregation of gelatin in alginate/gelatin blended hydrogel fibers, making the worse compatibility between alginate and gelatin. It also destroys the mechanical properties of alginate/gelatin blended hydrogel fibers. These alginate/gelatin blended hydrogel fibers might have a potential application in the biomedical fields. Highlights • Alginate/gelatin blended hydrogel fibers were successfully prepared. • There is part of gelatin remaining in the hydrogel fibers, because some of gelatin is solved in the coagulation bath. • There is an optimal additive amount of gelatin to improve properties of alginate/gelatin blended hydrogel fibers. [ABSTRACT FROM AUTHOR]

Changes in precipitation have the potential to cause dramatic changes in ecosystem carbon (C) cycling; however, it remains unclear whether different components of the net ecosystem exchange (NEE) (e.g., C uptake vs. release, plant vs. microbe respiration, above‐ground vs. below‐ground plant respiration) have similar or differential sensitivity to precipitation gradients.We conducted a manipulative field experiment (from 2015 to 2017) with six precipitation treatments, including 1/12 annual precipitation (P), 1/4 P, 1/2 P, 3/4 P, P and 5/4 P in an alpine meadow to investigate the responses of the NEE components.Over the 3 years, all C fluxes showed a nonlinear response to the precipitation gradients, except for root respiration. The most extreme drought treatment (1/12 P) caused strong reductions in NEE by 15.57%, gross primary productivity by 17.26% and ecosystem respiration by 19.05%, in contrast to the control. Plant respiration was more sensitive to precipitation change than microbe respiration, and above‐ground plant respiration was more susceptible than below‐ground respiration. Structural equation models revealed that the response of C fluxes under precipitation changes was primarily due to changes in the soil water content and above‐ground net primary productivity.Our findings indicate that future precipitation changes, particularly extreme drought, will decrease ecosystem C fluxes with different magnitudes, leading to a consequent reduction of NEE. These emergent ecosystem properties are essential for the improved elucidation of carbon cycle dynamics and benchmarking models, to predict ecosystem responses to precipitation changes. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Based on various comparable salen ligands, three synthesized CuIINaI-complexes present efficient catalytic activities for the coupling and cyclization reaction of 1,2-diaminopropane with nitriles towards 2-imidazolines. The catalytic results show that salen ligands with an electron-donating substituent and small steric hindrance improve the catalytic activity. [ABSTRACT FROM AUTHOR]

Visible‐light photocatalysis is a rapidly developing and powerful strategy to initiate organic transformations, as it closely adheres to the tenants of green and sustainable chemistry. Generally, most visible‐light‐induced photochemical reactions occur through single‐electron transfer (SET) pathways. Recently, visible‐light‐induced energy‐transfer (EnT) reactions have received considerable attentions from the synthetic community as this strategy provides a distinct reaction pathway, and remarkable achievements have been made in this field. In this Review, we highlight the most recent advances in visible‐light‐induced EnT reactions. Making light of synthesis: The distinctive reaction pathways provided by visible‐light‐induced energy transfer (EnT) has resulted in it receiving considerable attention. This Review discusses the most recent advances in visible‐light‐induced EnT reactions. [ABSTRACT FROM AUTHOR]

Photokatalyse mit sichtbarem Licht ist eine sich schnell entwickelnde und wirksame Strategie zur Initiierung organischer Umwandlungen, und sie folgt den Prinzipien einer grünen und nachhaltigen Chemie. Im Allgemeinen verlaufen die Reaktionspfade der meisten durch sichtbares Licht induzierten photokatalytischen Reaktionen über einen Einelektronentransfer (single‐electron transfer, SET). Neuerdings erfahren auch Energietransferreaktionen (EnT‐Reaktionen), welche durch sichtbares Licht induziert werden, beträchtliche Aufmerksamkeit, da diese Strategie einen spezifischen Reaktionsweg aufweist und bemerkenswerte Fortschritte in diesem Feld erzielt wurden. In diesem Aufsatz diskutieren wir die neuesten Fortschritte im Bereich der durch sichtbares Licht induzierten EnT‐Reaktionen. Sichtbare Photokatalyse: Durch sichtbares Licht induzierte Energietransferreaktionen (EnTs) haben beträchtliche Aufmerksamkeit erfahren, da sie spezifische Reaktionsmechanismen aufweisen. In diesem Aufsatz werden die neuesten Fortschritte in diesem Gebiet diskutiert. [ABSTRACT FROM AUTHOR]

Microgrid (MG) usually operates in medium/low-voltage systems, where the line impedance parameters are mainly resistive, and traditional P–f/Q–U droop control is no longer applicable. When the virtual complex impedance method is adopted, the resistance component of line impedance can be counteracted by a virtual negative resistance. Unfortunately, the improper design of the virtual negative resistance will result in an unstable system due to the problem of line impedance parameter drift and estimation error. According to the line parameters characteristics of the off-grid MG with medium/low voltage, the P–U/Q–f droop control is adopted in this study, where the virtual complex impedance composed of a virtual negative inductance and a virtual resistance is introduced in the control loop. The virtual negative inductance is used to reduce the power coupling caused by the inductive component of the system impedance. The virtual resistance is implemented to enhance the resistive component and adjust the impedance matching degree for raising the accuracy of power sharing. However, the power sharing is still affected by the system hardware parameters; meanwhile, the voltage deviation caused by the droop control and the virtual impedance exists. In this study, a novel voltage stabilization and power sharing control method based on the virtual complex impedance is investigated to achieve accurate power sharing without the impact of hardware parameters variations and to improve the voltage quality. Moreover, the small-signal model of the inverter-based off-grid MG with the proposed controller is established, which can be utilized to analyze the stability and dynamic performance of the system. Meanwhile, the control parameters can be sequentially determined. Analysis shows that the strategy is robust against the line-impedance parameter drift and the estimation error and has a large stability margin and fast dynamic-response speed. Finally, numerical simulations and experimental results are provided to verify the effectiveness of the proposed control method in comparison with traditional frameworks. [ABSTRACT FROM AUTHOR]

Two visible-light driven alkenylation reactions of unactivated alkyl bromides, which were enabled by the use of Ir(dF(CF3)ppy)2(dtbbpy)PF6 as the photocatalyst and (TMS)3SiH as the atom transfer reagent to activate the alkyl bromides, were described for the first time. These protocols can be used to produce a variety of alkenes from easily available feedstock with good reaction efficiency and high chemoselectivity under mild reaction conditions. To further demonstrate the applicability of the present strategy, the alkenylation of bioactive molecules and glycosyl bromides, as well as the alkynylation of unactivated alkyl bromides, was proven to be feasible. [ABSTRACT FROM AUTHOR]

Abstract Contraction mapping methods do not need to know about the concrete form of plant models like the Lyapunov method. This is the biggest advantage over other methods in the field of iterative learning control for example. However, it is difficult to use such a tool to analyze repetitive control systems. This paper proposes a contraction mapping method based on spectral theory to design a saturated repetitive controller for a class of nonlinear systems, where the derived necessary and sufficient condition on the spectral radius can reduce the conservatism as much as possible. The feasibility of our work is demonstrated through a robotic manipulator tracking example. [ABSTRACT FROM AUTHOR]

Abstract In a probe–drogue aerial refueling system, the drogue is affected not only by wind disturbances but also by strong disturbances from the tanker vortex and receiver forebody bow wave. Along with the aerodynamic disturbances acting on the receiver aircraft, it is difficult for the probe to capture the moving drogue in the docking stage. This paper studies the model of the probe–drogue aerial refueling system under aerodynamic disturbances, and proposes docking control method based on iterative learning control to compensate for the docking errors caused by aerodynamic disturbances. For receiver aircraft with different maneuverability, three control strategies are proposed to achieve a trade-off between safety and control precision. Furthermore, a practical method is proposed to predict the initial value of the learning controllers, which can significantly improve the iterative learning speed of the proposed methods. Finally, simulations demonstrate that the proposed control methods are simple and efficient for the docking control of autonomous probe–drogue aerial refueling. [ABSTRACT FROM AUTHOR]

Abstract: The high‐density polyethylene (HDPE) composites filled with four kinds of carbon blacks (CB) were prepared to investigate the effects of the size and content of the CB on the electrical properties of the HDPE/CB composites. It was found that the composites presented conductive percolation behavior, the CB with different size filled‐systems had different percolation thresholds; the higher the structure property of the CB, the larger the particle surface area, and the smaller the particle size, the better was the conductivity, and the lower was the percolation threshold of the composites. In addition, the HDPE/CB composites showed significant positive temperature coefficient (PTC) effect and negative temperature coefficient effect. The bigger the filler particle diameter, the higher was the PTC intensity of the HDPE composite systems under the same CB weight fraction. [ABSTRACT FROM AUTHOR]

Highlights • We have rephrase the highlights:1.Fire retardant cotton fabrics were prepared based on APTES, chitosan and sodium phytate by LBL. • The addition of chitosan further improved the fire retardancy of coated cotton fabrics. • The deposition of APTES, chitosan and sodium phytate obviously reduced the release of inflammable gases, and increased the release of nonflammable gases. Abstract Chitosan was added to cotton fabrics coated with sodium phytate and 3-Aminopropyl triethoxysilane (APTES) to further enhance the fire retardant property by the layer-by-layer (LBL) assembly. The surface morphologies before and after flaming and structure of coated cotton fabrics were evaluated by scanning electron microscopy and Fourier transform infrared analysis. The thermal degradation properties, fire retardancy, and combustion properties of this system were investigated by Fourier transform infrared analysis, thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) in the N 2 atmosphere, the thermogravimetric analysis in air atmosphere, limiting oxygen index test (LOI), vertical burning test and cone calorimeter test, respectively. Sodium phytate, chitosan and hydrolyzed APTES were successfully deposited and well distributed on the surface of cotton fibers. The LOI value of the coated cotton fabric with 15BL was 29.0%, and it extinguished at once in the vertical burning test, while the coated cotton fabrics with 5BL and 10BL were burned out. The deposition of sodium phytate, chitosan and hydrolyzed APTES led to the decrease of heat release rate, total heat release, total smoke release and smoke production rate. The promoted fire retardancy was assigned to thermally stable residuals formed on the surface of cotton fibers, which prohibited heat/mass transfer from combustion zone to polymer degradation zone. TG-FTIR results indicated that flame retardant cotton fabrics produced more nonflammable gases (CO 2 and H 2 O) and less combustible gases than them of the control sample did, increasing flame retardant properties of flame retardant cotton fabrics. [ABSTRACT FROM AUTHOR]

We investigate two-copy scenario of quantum teleportation based on Bell measurements. The detailed protocol is presented and the general expression of the corresponding optimal teleportation fidelity is derived, which is given by the two-copy fully entangled fraction that is invariant under local unitary transformations. We prove that under a specific case of the protocol, which is significant for improving the optimal fidelity, the set of states with their two-copy fully entangled fractions bounded by a threshold value that required for useful two-copy teleportation is convex and compact. Hence the witness operators exist to separate states that are useful for two-copy teleportation from the rest ones. Moreover, we show that the optimal fidelity of two-copy teleportation surpasses that of the original one copy teleportation. [ABSTRACT FROM AUTHOR]

The use of conventional antibiotic therapies is in question owing to the emergence of drug-resistant pathogenic bacteria. Therefore, novel, highly efficient antibacterial agents to effectively overcome resistant bacteria are urgently needed. Accordingly, in this work, we described a novel class luminogen of 6-Aza-2-thiothymine-decorated gold nanoclusters (ATT-AuNCs) with aggregation-induced emission property that possessed potent antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). Scanning electron microscopy was performed to investigate the interactions between ATT-AuNCs and MRSA. In addition, ATT-AuNCs exhibited excellent ROS generation efficiency and could effectively ablate MRSA via their internalization to the cells. Finally, tandem mass tag-labeling proteome analysis was carried out to investigate the differential expression proteins in MRSA strains. The results suggested that ATT-AuNCs killed MRSA cells through altering the expression of multiple target proteins involved in DNA replication, aminoacyl-tRNA synthesis, peptidoglycan and arginine biosynthesis metabolism. Parallel reaction monitoring technique was further used for the validation of these proteome results. ATT-AuNCs could also be served as a wound-healing agent and accelerate the healing process. Overall, we proposed ATT-AuNCs could serve as a robust antimicrobial aggregation-induced emission luminogen (AIEgen) that shows the ability to alter the activities of multiple targets for the elimination of drug-resistant bacteria. [Display omitted] • Provide a novel antimicrobial AIEgen of ATT-AuNCs for the treatment of MRSA. • Propose possible mechanism of ATT-AuNCs in killing MRSA. • Depth understanding the mode of action of ATT-AuNCs against MRSA at the proteome level. • Find 13 important differentially expressed proteins and their biological pathways. • Promote the healing of MRSA-infected wound. [ABSTRACT FROM AUTHOR]

• CUE had different sensitivity to clipping and warming. • Clipping significantly increased CUE due to the stronger positive effects of clipping on GEP than on ER. • Warming had a minor effect on CUE attributed to the synchronized increase in GEP and ER. Ecosystem carbon use efficiency (CUE) is a critical variable in quantifying the efficiency and capacity of an ecosystem to sequestrate carbon (C) from the atmosphere. However, how CUE responds to land-use change and climate warming remains elusive and lacks empirical evidence. We implemented a field manipulative experiment to examine the effects of clipping and warming on CUE in an alpine meadow on the Qinghai-Tibetan Plateau over 7 years. The results showed that clipping significantly increased CUE by 7.1%, which was mainly attributed to the stronger positive effects of clipping on gross ecosystem productivity (GEP, 13.0%) than on ecosystem respiration (ER, 5.3%). In contrast, warming had a minor effect on CUE due to the synchronized increase in GEP (8.8%) and ER (7.3%). There was no significant interactive effect of clipping and warming on CUE. Moreover, the dominance of grasses played a pivotal role in controlling the responses of CUE to clipping and warming by increasing ecosystem C uptakes but decreasing microbial decomposition. Soil temperature and above-ground net primary productivity also contributed to the changes in CUE under clipping and warming. These results suggest that clipping once a year at the end of the growing season could increase the efficiency of this alpine meadow for C sequestration, while climate warming could not change ecosystem C use efficiency. We highlight that the dominance of grasses is an emerging property in determining CUE under land-use change and climate warming in grasslands. [ABSTRACT FROM AUTHOR]

To guide the movement of a robotic swarm in a corridor‐like environment, a curve virtual tube with no obstacle inside was designed in our previous work. This article generalizes the controller design to the condition that all robots have self‐localization drifts and precise relative navigation, where the flocking algorithm is introduced to reduce the negative impact of the self‐localization drift. Similar to the "many wrongs principle," it is shown that the cohesion behavior and the velocity alignment behavior are able to reduce the influence of the position measurement drift and the velocity measurement error, respectively. For convenience in practical use, a modified vector field controller with five control terms is put forward. Finally, the effectiveness of the proposed method is validated by numerical simulations and real experiments. [ABSTRACT FROM AUTHOR]

Formononetin is an isoflavone phytoestrogen mainly existing in leguminous plants such as Trifolium pretense, Spatholobus suberectus, etc. Studies have proved that formononetin has good anti-inflammatory, antitumor, antioxidant, antidepressant, anxiolytic and other pharmaco- logical effects. This paper summarizes the pharmacological action and molecular mechanism of formononetin, in order to provide a theoretical basis for the development and clinical application of formononetin. [ABSTRACT FROM AUTHOR]

This paper presents an additive-state-decomposition-based attitude tracking control method for a class of bank-to-turn aerial vehicles subject to unknown disturbances and nonlinear coupling. This method ‘additively’ decomposes the original tracking problem into two more tractable problems, namely a tracking problem for a deterministic nonlinear ‘primary’ system, and a disturbance rejection problem for a linear time-invariant ‘secondary’ system. Based on the decomposition, a backstepping controller is designed for the primary system to track the reference attitude signal, and a proportional-integral controller is applied to the secondary system to compensate for the disturbances. Finally, the two designed controllers are combined to achieve the original control objective. By using additive state decomposition, the proposed control method with two degrees of freedom can consider tracking task and disturbance rejection task respectively. Simulation results illustrate that the proposed controller can track the reference attitude signal and compensate for disturbances meanwhile. Additionally, the ASD-based controller outperforms the traditional backstepping controller in the presence of unknown disturbances and input delay, and the robustness of the full system can be improved by adjusting the controller parameters of the secondary system. [ABSTRACT FROM AUTHOR]

An achiral 2,2'-bipyridyl-3,3'-dicarboxylate (H2LN) can be oxidized to a C2 axially chiral N-oxide analogy (R,S)-2,2'-bipyridyl-3,3'-dicarboxylate-1,1'-dioxide ((R,S)-H2LNO), converting normal bipyridyl-N to a charge-separated N-oxide group. The achiral H2LN connects the Ag(I) ions into a 4-connected mesomeric 3D network [Ag4(LN)2·(H2O)]·3H2O (1). However, as expected, with the introduction of N-oxide groups, {Ag4[(R,S)-LNO]2·2(H2O)}·H2O (2) and {Ag2[(R,S)-LNO]}·H2O (3) contain right- and left-handedness homochiral layers. Such opposite handedness layers are linked together to give a racemic compound in 2 but meso double-layers in 3. Notably, both ligands in 1-3 support argentophilic interactions. Moreover, a luminescent comparison of 1-3, pyridyl-N, and its functional N-oxide ligands is also investigated in detail. [ABSTRACT FROM AUTHOR]

Sodium sulphide was used to dissolve the waste hair. The optimal reaction conditions were determined via single factor comparison experiments and orthogonal experiments. The results showed that the optimum conditions were as follows: the concentration of Na2S·9H2O was 60 g/L, the concentration of urea was 2 g/L, the concentration of sodium dodecyl sulfate was 10 g/L, the dissolving time was 120 min, and the melting temperature was 80°C. In this condition, the dissolution rate reached 92.29% and the extraction rate of keratin reached 62.98%. The results of TGA and FT-IR showed that there were no significant changes in the stability of keratin, and the special functional groups contained were the same as those of human hair. [ABSTRACT FROM AUTHOR]

A dual visible light photoredox and nickel-catalyzed cross-coupling reaction of 2-arylaziridines and potassium benzyltrifluoroborates is described for the first time. This strategy features high functional group tolerance, exclusive regioselectivity for reaction at the more hindered C-N bond, easily accessible substrates, and mild redox-neutral reaction conditions. A variety of diversely substituted ß-substituted amines are obtained in generally good yields. [ABSTRACT FROM AUTHOR]

An efficient and practical approach towards phosphine oxides and phosphonates has been successfully developed through the desulfonative coupling of various sulfones with secondary phosphine oxides and phosphites. This protocol features simple experimental procedures under mild conditions (i. e., catalyst- and oxidant-free, room temperature and open to air). By doing so, a variety of alkynyl, alkenyl and allyl phosphine oxides or phosphonates can be produced in generally good reaction efficiency and selectivity (31 examples, up to 98% yield). [ABSTRACT FROM AUTHOR]